higgins y kristensen 1986 loricifera

7/28/2019 Higgins y Kristensen 1986 Loricifera

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SERIES PUBLICATIONS OF THE SMITHSONIAN INSTITUTIONEmphasis upon publication as a means of "diffusing knowledge" was expressed by the firstSecretary of the Smithsonian. In his formal plan for the Institution, Joseph Henry outlined aprogram that included the following statement: "It is proposed to publish a series of reports,giving an account of the new discoveries in science, and of the changes made from year to yearin all branches of knowledge." This theme of basic research has been adhered to through theyears by thousands of titles issued in series publications under the Smithsonian imprint,

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S M I T H S O N I A N C O N T R I B U T I O N S T O Z O O L O G Y N U M B E R 4 3 8

New Loricifera from SoutheasternUnited States Coastal WatersRobert P. Higginsand Reinhardt Mtfbjerg Kristensen

SMITHSONIAN INSTITUTION PRESSCity of Washington

1986


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A B S T R A C THiggins, Rob ert P., and Reinhardt M0bjerg Kristensen. New Loriciferafrom Southeastern United States Coastal Waters. Smithsonian Contributionsto Zoology, number 438, 70 pages, 87 figures, 1 map, 1986.Eight newspecies, comprising two new genera and a new family of Loricifera, aredescribed from the meiobenthos of medium to coarse sandy subtidal habitats,289-439 m deep, off the coast of North and South Carolina. Five of the newspecies are placed in the new genus Pliciloricus and three are placed in thenew genus Rugiloricus. A new family Pliciloricidae is established for the twonew genera. The diagnosis of the phylum Loricifera is emended to includethe new taxa. The morphology of loriciferans is re-evaluated and newterminology is established. A discussion of the biology and systematic rela-tionships of the phylum is included.

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and isrecorded in the Insti tution's annual report , Smithsonian Year. SERIES COVER DESIGN: The cora lMontastrea cavernosa (Linnaeus).Library of Congress Cataloging in Publication DataHiggins, Robert P.New Loricifera from southeastern United States coastal waters.(Smithsonian con tributions to zoology ; no. 43 8Bibliography: p .Supt. of Docs, no.: SI 1.27:4381 LoriciferaS outhern StatesClassification. 2. LoriciferaAtlantic Coast (U.S.)Classi-fication. I. Kristensen , Rein hard t M0b jerg. II. Titl e III SeriesQL1.S54 no. 438 59 1s [595.1 '851 85-60024[QL391.L67]


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ContentsPageIn t roduct ion 1Methods 2Localities 3Abbreviations 4Acknowledgments 5Phylum LORICIFERA Kristensen, 1983 5O r d e r NANALORI CI DA Kristense n, 1983 5

PLICILORICIDAE, new family 5Key to the Ge ner a of Pliciloricidae 6Pliciloricus, new genus 6Key to Adults of Pliciloricus 6Key to Larvae of Pliciloricus 7Pliciloricus enigmaticus, new species 7Pliciloricus dubius, new species 10Pliciloricus gracilis, new species 12Pliciloricus orphanus, new species 16Pliciloricus profundus, new species 18Rugiloricus, new genus 21Key to Adults of Rugiloricus 21Key to Larvae/Post- larvae of Rugiloricus 22

Rugiloricus carolinensis, new species 22Rugiloricus cauliculus, new species 26Rugiloricus ornatus, new species 29Morphology and Term inolog y in the Loricifera 31Biology of the Pliciloricida e 35Systematic Relationships in the Pliciloricidae 36Litera ture Cited 38Figures 39

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New Loricifera from SoutheasternUnited States Coastal WatersRobert P. Higginsand Reinhardt Mtfbjerg Kristensen

IntroductionThe Loricifera Kristensen, 1983, is a phylumof marine microscopic metazoans recently de-scribed from the meiobenthos of subtidal coarsesediments. The phylum, one of three describedduring this century (Pogonophora: Caullery,1914; Johansson, 1937; Ivanov, 19 63; Gnathos-tomulida: Ax, 1956; Riedl, 1969), brings thetotal number of living animal phyla to 39, afigure that includes seven unicellular eukaryoticprotists (Parker, 1982), and continues recogni-tion of the Pogonophora as a separate phylum,no t as a class in the phylum A nnelida as proposedby van der Land and N0rrevang (1977). Theknown existence of the Loricifera dates back toMay 1974, when a single adult male was foundin a coarse-sand sample taken off the coast ofNorth Carolina by the Senior author in collabo-ration with several colleagues (Coull, et al.,1977). Originally, the specimen was assumed tobe a juvenile stage of an undescribed priapulid,a phylum that, at that time, was undergoingsignificant redefinition because of the discoveriesof Tubiluchus corallicola van der Land, 1968, and

Maccabaeus tentaculatus Por, 1973. Ironically,Tubiluchus, a common inhabitant of coarse sedi-Robert P. Higgins, D epartment of Invertebrate Zo ology, NationalMuseum of Natural History, Smithsonian Institution, Washing-ton, D.C. 20560. Reinhard t M tbjerg Kristensen, Institute of CellBiology and Anatomy, University of Copenhagen, DK-2100 Co-penhagen, Denmark.

ments, is represented by a yet unidentified spe-cies in the same habitat as the loriciferans de-scribed in this paper.The year following the appearance of the sin-gle, then unidentified, specimen from the coastof North Carolina, the jun ior au thor found asimilar aberrant invertebrate near Helsing0r,Denmark while he was engaged in a study ofgnathostomulids. This specimen was more roti-fer-like, about 80 /tm in length, and came fromcoarse sediments, 10 -12 m deep. Unfortunately,it was lost during preparation for transmissionelectron microscope examination (Kristensen,1983). Between 1976 and 1979, and again in1982, additional specimens, not necessarily thesame species, were found by the junior authorwhile investigating meiofauna from coarse sedi-ments (100-11 0 m depth) outside the h arbor ofGodhavn, Greenland. Because these specimensexhibited no evidence of reproductive organs,they, also, were thought to be larval stages, per-haps larval stages of a priapulid considering,again, the recent discoveries by van der Land(1968) and Por (1973).In 1980, a specimen found in coarse corallinesand from the Chesterfield Reefs (Coral Sea),was sent to the junio r a utho r, who recognized itas another larva of the yet undetermined taxon.So far, only larval stages were available for study .The mystery of the identity of these aberrantinvertebrates, among the smallest metazoans

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SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

know n, finally was solved when the jun ior au tho rfound both larva and adults together in coarsesediment dredged up near Roscoff, France, inApril 1982 (Kristensen, 1983). Since then, theknown distribution of loriciferans has been ex-panded to include the Azores Islands (one speci-men from the Barlett Expedition, 1975), the eastcoast of Florida (Kristensen, 1983), the Gulf ofMexico (USNM Accession 360974), the Mediter-ranean Sea (Soetaert , Heip, and V incx, 1984,and pers . comm .photograph of adult), and thePacif ic Ocean (B. Burnett , pers. comm.pho-tograph of Higgins-larva; Y. Shirayama, pers.comm.photograph of adult). For a more com-plete history of the events leading to the descrip-tion of this new phylum, the reader should con-sult Kristensen, 1983.

METHODS.The specimens upon which thisstudy is based were from five samples of coarsesand from depths of 289 m and 439 m on thecontinental shelf of the coast of North Carolinaand South Carolina. The sample from which thefirst loriciferan was extracted was from materialconsidered unacceptable for the qualitative studybeing conducted during cruise E-5-74 of theR/V Eastward, 14 May 1974 (Coull et al., 1977).Th is sample was made using a Reinick Box C orer(10 cm X 20 cm). The coarse sand, about 1 literin volume, was processed. The single specimenwas preserved in 70% ethanol.A second series of four samples was madeduring a cruise of the R/V Cape Hatteras, 1 6 - 1 9Novem ber 1983. Thes e samples were taken byan anchor dredge designed by the senior authorto remove a layer of sediment 450 cm wide andup to 10 cm deep. When filled, about 50 litersof sediment are collected by the 120 /am meshnet of this apparatus. The sediment was releasedfrom the net into two large containers, one ofwhich was used for the extraction of macrofaunaand sediment analysis, the other processed simi-lar to that described by Kristensen and Higgins,1984, which was repeated here as follows.Several handfuls of sediment were placed in acontainer with about 5-8 liters of fresh water.The treatment of coarse marine sediment withfresh water (Kristensen and Higgins, 1984) has

been found to be a more effective extractiontechnique for hard-bodied meiofauna than theuse of an isotonic solution of m agnesium chlo ride(Hulings and Gray, 1971). The sediment wasgently agitated in the fresh water for about 10-15 seconds, then it was decanted through a 62^m mesh nylon sieve. This process was repeatedtwice for each unit of sediment preserved. Thematerial retain ed by the conical-shaped sieve waswashed with additional fresh water into the bot-tom of the sieve, which was quickly em ptie d intoa container of 6% buffered (sodium borate) for-malin to which a tincture of rose bengal wasadded in sufficient quantities to stain all orga-nisms in order to facilitate sorting. This proce-dur e was repeated unti l the entire sediment sam-ple had been preserved.

Sorting was cond ucted using 50X magnifica-tion of a stereomicroscope. Specimens of lorici-ferans were placed in either a solution of distilledwater containing 2% glycerin that was slowlyevaporated to glycerin over 5 to 7 days or to aspecial tube, sealed with 40 nm mesh nylon net,and placed in a small vessel of distilled water.Ethanol was added slowly to the distilled waterover a period of 48 hours to affect a 100%ethanol medium. The tube and i ts contents weredried in a critical point depression apparatususing carbon dioxide. Specimens were mountedon 12 mm glass coverslips covered with Elmer'sglue that were affixed to aluminum SEM stubsand coated with gold-platinum. SEM examina-tions were made with a Cambridge Stereoscan250 MK2 and Stereoscan MK2.

Glycerin-impregnated specimens weremounted in this same medium or in a modifiedHoyer's medium on glass microslides or on Cobbaluminum slide frame mounts (Higgins, 1983).Microslide preparations were sealed with Mur-rayite. Illustrations were made with the aid of acamera lucida. Some observations seen only bySEM were added to the i l lustrations. Photo-graphs were taken through a Zeiss UniversalMicroscope equipped with phase and interfer-ence contrast optics.Specimens of new species have been depositedin the Zoological Museum of Copenhagen, Den-


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NUMBER 438 3mark, and in the National Museum of Natural LOCALITIES.Five sampling sites (Map 1) in-History, Smithsonian In stitution, un der the cat- volving two general areas of the continental shelfalog num bers of the former United States Na- of North and South Carolina, both un der thetional Museum (USNM). influence of the Gulf Stream, provided the ma-

79

36-

35

32^

Cape Romain

79

78 75C

-38

Cape Hatteras- 3 5 C

1834R H 1 8 3 3

RH1 8 3 9 + + RH1837

- 3 4 C

- 3 2 *

78' 77'MA P l.Sampling localities for plicilorid loriciferans.


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terial for this study. The collecting data for ma-terial examined will be referred to by the seniorauthor's collection numbers (RH). These dataare as follows:RH 1695 14 May 1974; col. R.P. Higgins; from mediu m

(quartz) sand, 400 m depth, ~195 km east ofCape Fear, North Carolina, USA (3407.2'N,7558.6'W).

RH 1833 16 Nov 1983; col. R.P. Higgins; from med ium(quartz) sand, 430 m depth, -~195 km east ofCape Fear, North Carolina, USA (3406.9'N,7558.4'W).

RH 1834 16 Nov 1983; col. R.P. Higgins; from med ium(quartz) sand, 439 m depth, ~195 km east ofCape Fear, North Carolina, USA (3407.4'N,7557.0'W).RH 1837 19 Nov 1983; col. R.P. Higgins; from mediu m(oolytic) sand, 294 m depth, 195 km east ofCape Romain, South Carolina, USA(3258.8'N, 77O18.1"W).

RH 1839 19 Nov 1983; col. R.P. Higgins; from mediu m(phosphorite) sand, 289 m depth, 195 km eastof Cape Romain, South Carolina, USA(3303.7'N, 7722.07'W).

ABBREV IATIONS.The following abbreviationsare used in the illustrations.atadafanapa ratbabebghibtclCOcpcscs,CSvClI)doeded,ed2esex

anal coneapodeme on the mouth coneanal fieldanusanal plateanal ridgeaccessory tooth (cl)bar-shaped structure of midventral plicabuccal canalbuccal canal glandbrainbasal plate of toeclaw-tipped spinoscalid (sr4)collarcollar poreclavoscalid (si-,)ventral clavoscaliddorsal clavoscalidclaw-tipdorsaldouble-organedge of loricaedge of larval loricaedge of adult loricaesophaguslarval exuvium

fl flosculus (Pliciloricus-type)fl, anterior flosculusfla poste rior flosculusgu gutha hairho hook-sh aped scalid of larval exuviumia interna l arma ture of larval buccal canalin introvertin, introvert of larval exuviumiii;, introvert of adult exuviumlc larval closing appara tu slo loricalo , lorica of larval exuviumlo-i lorica of adult exuviumIr, primary doubl e ridge of loricaIr;, sec onda ry dou ble rid ge of loricaIs, anterolateral setaIs-, anteroventral setame mout h coneme , first region of mouth conemc 2 second region of mouth conemc thi rd region of mouth conenih middorsal hook (modified sr9)mo moltin g bodymp midd orsal platemr mucroms midventral setae of mouth conenit mou th tubemu musclemv mid ventra l scalidnf flosculus (Nanaloricus-type)ne nephridiopore(?)or oral ridgeos oral styletot oral toothph pharynx bulbpi, plicapi,, midventral modified plicapo pore on trichoscalid plateps penil e spine(?)pt toe gland porere ridgeri transverse ridge of loricaro rosette structureru ruffsc scalidse, posterodorsal setase-j posterolateral setase:, posteroterminal setasp spine on spinoscalidsr,-srH scalid row 1-9ss spinoscalidsu sculpture of loricate testisth thorax


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NUMBER 438th ,th .tlto

thorax of larval exuviumthorax of adulttelescopic region of mouth coneto etp i- tp s trichoscalid plates 1-3tr

tr,tr,,tsV

trichoscalidprimary trichoscalidsecondary trichoscalidtrichoscalid plate spineventralACKNOWLEDGMENTS.The authors weremost grateful for the collecting opportunitiesmade possible by the National Science Founda-tion's gran t GA -42792 to B.C. Coull, Universityof South Carolina, grant GC-00005 to DukeUniversity for R/V Eastward operations, andgrant DPP-8026535 to R.Y. George, Universityof North Carolina at Wilmington, and for thegenerous cooperation of these two colleagues.We have received valuable technical assistancefrom S. Braden, G. M0bjerg Kristensen, S.A.Petry, M.L. Wallace and H. Wolf, as well as thecaptains and crews of the R/V Eastward (1974)and R/V Cape Hatteras (1983). The carbon dustillustrations were created by the Smithsonian'sC. Gast and M. Ryan. Our colleagues B.C. Coulland E.E. Ruppert have critically reviewed this

manuscript and made many valuable suggestions.This research was supported financially in partby project funds to the senior author from theSmithsonian Marine Station at Link Port and bya grant from the Sumner Gerard Foundation.Th e participation of the jun ior a uth or in thiswork was supported by portions of the seniorauthor's funds in addition to a NATO ScienceFellowship, the Danish Na tural Science ResearchCouncil, and a Smithsonian Postdoctoral Fellow-ship.Phylum LORICIFERA Kristensen, 1983

EMENDED DEFINITION.Adults 225-383 /imlong, bilaterally symmetrical marine metazoans.Body consisting of a spherical, eversible head or"introvert," a neck and thorax, all retractableinto a loricate abdominal region. Prominentmouth cone with 8-9 oral stylets or 6-16 oral

ridges, and an extrusible cuticularized buccalcanal centered in the head; head armed with upto 9 variably distinct rows of appendages orscalids. Sexual dimorphism may be apparent inthe structu re of the first row of scalids or clavos-calids. Thorax (sensu Kristensen, 1983) appearsto consist of 2 "segments," the anterior portion,now called the neck, with appendages consistingof trichoscalids with basal plates, and a posteriorportion, which retains the name thorax and lacksappendages. Abdomen covered by sclerotizedlorica, consisting of 6 plates with hollow spinesalong anterior margin or 22 or more folds ofplica. Flosculi, when present, located posteriorlyon lorica. Saccate gonads open terminally. Onepair of protonephridia present. Myoepithelialpharynx bulb with or without placoids.Higgins-larva 80-385 ftm long, with samebody regions as adult. Mouth cone unarmed orwith 6 -12 oral stylets; internal arm ature may bepresent. Head always with 8 clavoscalids and upto 7 rows of spinoscalids, a single middorsal spi-noscalid always modified. Sometimes w ith collar-like area, between seventh row of scalids andthorax, presumed to be a closing apparatus;sometimes double ventral plates formed fromsame area act as a closing appa ratus. Tho rax with5-6 rows of plates formed from transverse andlongitudinal folds. Lorica longitudinally folded,2-3 locomotory and/or sensory setae present onanterio r margin of lorica. Two toes located cau-dally; 2 or 3 sensory setae present on posteriormargin of lorica. Development by series of sev-eral larval stages; postlarval stage precedes defin-itive adult stage o r larva molts directly into adult.

Order NANALORICIDA Kristensen, 1983EMENDED DEFINITION.Same as phylum.

PLICILORICIDAE, new familyDEFINITION.Adults 330-383 nm long. Tri-partite mouth cone surrounded by 6-1 2 thin oralridges; no annulation in the thin buccal canal;


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placoids lacking in the pharyngeal bulb. Twokinds of unbranched clavoscalids; 2 second rowmidventral spinoscalids variously united to form"double-organ," occasionally well sclerotized; nogap between the spinoscalids on the head and thetrichoscalids on the neck. Lorica only slightlysclerotized, with 22 or more longitudinal folds;flosculi present or absent (in one of two genera).Anus-gonopore complex apparently positionedventroterminally.


Higgins-larva 110-375 /xm long, some latestages larger than adults. Mouth cone with oralstylets; single ventral oral seta may be present.Internal armature posterior to pharynx some-times present. Only 2 pairs of locomotory/sen-sory setae on anterior edges of lorica; 2-3 pairsof sensory setae on the posterior edges of lorica.Toes with large glands, smooth margined. Noflosculi.

T Y P E GENUS.Pliciloricus, new genus.

Key to the Genera of PliciloricidaeAdult with 15single trichoscalids [Figure 76], lorica not well defined (cuticle

thin); with 30-60 longitudinal folds or plica; larva with small, ventrallyoriented toes if present, 4 pairs lorical setae if present [Figure 77]Rugiloricus, new genus

Adult with 8 single and 7 double trichoscalids [Figure 1], lorica well defined(cuticle thick); with 22 longitudinal folds or plica; larva with straight,terminal toes, five pairs of setae [Figure 4]

Pliciloricus, new genus

Pliciloricus, new genusDIAGNOSIS.Adults 185-310 /xm long, with a

well-defined tripartite mouth cone, with 8strongly cuticularized oral ridges and 4 thinneroral ridges; buccal canal weakly cuticularized,telescopically retractable to only slight extent;pharyngeal bulb glandular, without placoids.With 8 more or less pod-like clavoscalids. Com-plex cuticular formation of 14-30 thin fiberssurrounding base of the mouth cone as a ruff.Double trichoscalids present. Lorica well de-fined, with 22 slightly sclerotized plicae. Two ormore pairs of two different kinds of flosculi onposterior region of lorica.

Higgins-larva 130-305 /xm long, with 6 oralstylets in mouth cone; buccal canal with internalarmature consisting of a tri- or hexaradially sym-

metrical structure connected to pharyngeal bulb.Eight clavoscalids present, may be one of twotypes; area between last row of scalids and tho-racic plates forming collar-like closing apparatus.Two pairs of locomotory/sensory setae at ante-rior edge of lorica; lorica consisting of only onepiece with many longitudinal folds; 3 pairs oflorical setae. Toes short to very long, may reachanterior edge of lorica, hollow with glandulartissue inside. Anus dorsoterminal.

TYPE-SPECIES. Pliciloricus enigmaticus, newspecies.

COMPOSITION. Pliciloricus enigmaticus, newspecies; P. dubius, new species; P. gracilis, newspecies; P. orphanus, new species; P. profundus,new species.

ETYMOLOGY.From the Latin plica (fold) pluslorica (corset); masculine gender.

Key to Adults of PliciloricusTwo spinoscalids adjacent to ventral midline, row 2, fused except for

terminal region (double-organ) [Figure 1] 2Two spinoscalids adjacent to ventral midline in row 2 not fused or only

fused near their base 3


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NUMBER 4382. The lorica with two pairs of P-flosculi and a rosette structure; claw-tippedspinoscalids in row 3 with single claw-tip and 4-5 subterminal accessory

teeth [Figure 1] P. enigmaticus, new speciesThe lorica with a single pair of P-flosculi and 3 pairs of lateral N-flosculi;claw-tipped spinoscalids with single claw-tip and a single subterminalaccessory tooth [Figure 29] P. dubius, new species3. The lorica with a single pair of P-flosculi; claw-tipped spinoscalid withdouble terminal, strongly curved claw-tip; mouth cone without tube[Figure 48] P. profundus, new speciesThe lorica with a single pair of P-flosculi and at least one pair of N-flosculi; claw-tipped spinoscalid without accessory teeth; mouth conewith a long tube [Figure 37] P. gracilis, new species

Key to Larvae of Pliciloricus1. To es shorte r than the lorica 2To es same length or longer than the lorica 32. Mouth opening with 6 oral teeth and 6 oral stylets; collar well definedwith 7 pores; toes with m ucros [Figure 39]. . . . P. gracilis, new speciesMouth opening with a valvate structure; collar indistinct; toes short andsetae-shaped [Figure 4] P. enigmaticus, new species3. Mouth opening with a valvate structure; collar well defined with 7 thinareas; toes very long and thin [Figure 49]. . .P. profundus, new speciesMouth opening surrounded by hairs; collar not well defined; toes longand robust [Figure 47] P. orphanus, new species

Pliciloricus enigmaticus, new speciesFIGURES 1-28

DIAGNOSIS.Adults 160-268 ^m long (notincluding mouth cone), with double-organ con-sisting of 2 second-row midventral spinoscalidsfused the basal half of their length, highly mod-ified, strongly sclerotized, rigid; 15 third-rowspinoscalids claw-tipped with 4-7 teeth, alternat-ing with 15 unmodified spinoscalids. Lorica with7 transverse cuticular r idges and longitudinaldouble r idges; 2 lateroventral plates of caudalregion each with 2 papillate flosculi ("Pliciloricus-flosculi"); large rosette structure, consisting of 6cells with central pore (gonopore?) on midventralcaudal plate. Terminal anus.Higgins-larva 200-305 nm long, mouth coneapparently without ventral oral setae (only thelarval exuvium was found). Internal mouth ar-mature hexaradially symmetrical, with 6 stylet-like structures, each with a furca joining the

pharyngeal bulb; mouth opening sur rounded by6 valves; cuticular lining in anterior part ofmo uth cavity suppo rted by 6 cuticular rods. Fo urventral clavoscalids broad with terminal spine; 4dorsal clavoscalids slightly narro we r; spinoscalidsrelatively long, 15-22 pm (scalids were difficultto see in the larval exuvium). Collar not welldefined and nearly continuous with posteriorlyadjacent rows of thoracic plates; with 2 pairs ofrelatively short anterior setae, with small hairs;lorica sculptured, with midtransverse constr ic-t ion, and 5-6 transverse r idges. Toes straight,small (40-58 fim), each with pointed tip; with 2pairs of sensory setae, each with an enlarge d ba se,at posterior end of lorica; 2 short spines presenton anal plate. Flosculi not observed, but couldbe present.MA TER I A L EXAMINED. Type Material: T h eholotype is an adult female, 238 nm long (Figures1, 6) from station RH 1834. The allotype is anadult male (224 /xm long) (Figure 7) also from


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8 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

station RH 1834. Paratypes include 1 adult malefrom station RH 1695 (Figures 2, 5); 3 larvaemol t ing to adul ts , 1 adult male and 1 adul t exu-vium from station RH 1833; 1 adult female(squash-preparation), 1 newly molted female, 1female(?) (presumed dead at the time of collec-tion), 1 newly molted male, 12 larvae molting toadul ts , 2 larval exuvia with newly molted adults,5 adult exuvia (Figure 8), 1 adult female(?) (un-mounted) from station RH 1834. SEM prepara-tions include 1 adu lt male(?) mo unte d on stub 83and 1 larva molting to adult (Figures 23-28)moun ted on stub 8 4, both from station RH 1837.A total of 34 specimens were examined.In addition to the holotype (USNM 98556)and allotype (USNM 98557), 16 paratypes(USNM 98558) and the SEM specimens havebeen deposited in the National Museum of Nat-ural History, Washington, D.C.; all other para-types have been deposited in the Zoological Mu-seum, Copenhagen.ETYMOLOGY.From the Latin enigmaticus(puzzle); masculine gender.DESCRIPTION.The holotypic female (F igures

1, 16) is 238 nm long. The mouth cone, notcompletely extended in the holotype, is 38 fimlong and consists of three regions (Figures 11,12). The basal portion of the mouth cone haseight retractor muscles, each attaching distally toa cuticular apodeme. The second region, thebroadest part of the mouth cone, has 16 thincuticular plates, with eight double ridges, 10 /tinlong. The internal structure of the third regionconsists of a cuticularized tubular extension ofthin, flexible buccal canal, abo ut 2 nm in diame-ter, which can be withdrawn telescopically intothe second region of the mouth cone. Eightprimary and four secondary ridges are visible atthe surface of the third region. Each of the eightprimary ridges is continuous with those of thesecond region of the mo uth cone, which attachesto an apodeme (Figure 11, ad), which, in t u rn , iscontinuous with one of the eight retractor mus-cles of the first region. The four secondary ridgesare difficult to observe and appear to be thick-enings of the internal cuticular surface. A lthoug h

the third region varies in length depending uponthe amount of extrusion, the 12 r idges appear tobe a consistent 20 /im in length, twice as long asthe eight double r idges of the second region ofthe mouth cone.A complex cuticular formation of 14-16 verythin fibers surrounds the base of the mouth coneas a "ruff" (Figure 17, ru), hence we have sonamed it. These fibers are continuous with aninternal r ing-shaped structure behind the phar-ynx bulb. As part of the introvert , the ruff prob-ably functions in the retraction of the mouthcone. In one specimen (RH 1834) the ruff wasfully everted and the mouth cone fully extended.Each of th e 14-16 fibers was coiled nea r the baseof the first two rows of scalids; each coiled por-tion was associated with a small plate.

The head ( introvert) has nine rows of appen-dages. The first row consists of eight very large,pod-shap ed clavoscalids, identical in both female(Figure 1) and male (Figures 2, 7). One marginof each clavoscalid is heavily reinforced for sup-por t and projects slightly beyond the otherwiseblunt tip. Each clavoscalid is compar tmental izedby 12-13 internal transverse walls, resembling aleguminous pod. The second row of appendagesconsists of seven leg-like scalids; two, at the ven-tral midline, are partially fused basally and formthe double-organ, ~90 fim long (Figure 17, do).This specialized appendage is more sclerotizedthan other head appendages and stiff hairs occurnear its base. The mouth cone, when ext ruded,lies between the two rami of the double-organ.Inside the two rami of th is appen dage, ~40 nmfrom the base, are two crescent-shaped cuticularstructures. The seven scalids of the dorsal h alf ofthis row are much larger (~ 12 0 /tm) than thoseon the ventral half (~100 /im). In a partiallyextended specimen (Figure 2), two dorsal leaf-l ike structures were apparent, bu t could not beseen in any other specimens.

The th i rd row of scalids consists of 15 smaller"leg-like" appendages with a double basal swell-ing. Each spinoscalid is joi nte d ab ou t 20 nm fromthe base; two stiff hairs are on each side of thistubercular joint .


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NUMBER 438The fourth row of scalids consists of 15 spi-noscalids alternating with 10-15 shorter claw-tipped spinoscalids, each with a slightly bulbousbased proximal segment and a serrate terminalsegment with 4 -7 subterminal teeth (Figures 15,18).Th e fifth through seventh rows of head appen-dages are very uniform in appearance; each ap-pendage consists of a short basal segment andelongate terminal segment; there are 30 of thesespinoscalids in each row. Th e eigh th row also has30 spinoscalids, but these differ in having aslightly spinose basal plate and an elongate ter-minal segment with small spines arranged as

barbs of a feather. T he ninth row consists of 30small, beak-like appendages, each w ith a tricuspidtip.The next row of appendages, eight single tri-choscalids alternating with seven double trichos-calids, is situated on an area intermediate be-tween the head and thorax that we have calledthe "neck," an area more clearly recognizable inthis family than in the Nanaloricidae. The neckhas two single midventral trichoscalids and onedouble middorsal trichoscalid as in all Plicilori-cidae. Th e do uble trichoscalids each have a singlebase from which the larger or primary elementextends; the sm aller or secondary elemen t origi-nates on the shaft of the primary element. Incross-section, the trichoscalids appear flat with acentral canal in which lies a cilium. The marginsof the trichoscalids have widely separated serra-tions that, at the distal end, form a slight tuft(Figure 19). The double trichoscalids have alarge basal plate with a crescentic depression.Two accessory basal plates (Figure 27) are situ-ated above the main or lower basal plate. Themiddle basal plate has a small spine (Figure 27,tp2) and a large pore. The upper basal plate istriangular. The single trichoscalid only has thelower basal plate; the middle basal plate ismissingand, instead of the upper basal plate, a smalltricuspid tooth is present. Superficially, the in-sertion of the trichoscalid on th e lower basal platemakes it appear as though the trichoscalidemerges from a hole in the plate.

The thorax has no appendages; its cuticle isvery thin and consists of three rows of folds orplates (only the first row is easily seen). Theentire thoracic region, along with the neck, iscapable of being withdrawn into the loricatedabdomen.Th e lorica on the abdom en is well developed.Its edge is separated from the thorax by 22 moreor less crescent-shaped structures (Figures 1, 3),which correspond with 22 primary longitudinaldouble ridges of the lorica. The area betweenthe longitudinal double ridges is called the plica(Figures 1, 13). In the middle of each plica is anelevation called the secondary do uble ridge. T hemidventral plica (Figures 1, 14, p^) is twice asbroad as the others, and the anterior part has acharacteristic sculpture that suggests that themidventral plica consists of two fused plicae.The midventral plica is divided into anteriorand posterior portions by a transverse line. Theposterior region has a large rosette structureconsisting of six cells surro und ing a pore (Figures1, 16, 2 1, ro), which we suspect may be a gono-pore, but no other loriciferans have a ventralgonopore. Three to four anal ridges (Figure 21,ar) extend from the rosette to the caudal end.Two pairs of papillate flosculi are located lateralto the midventral plate (Figures 1,21,22). Thesesense organs are very different from the flosculidescribed in Nanaloricus. To differentiate be-tween the two types we have named the Nanalor-icus-type flosculus the "N-flosculus" and the Pli-ciloricus-type flosculus the "P-flosculus." The for-mer type consists of a cluster of micropapillaesurrounding a pore; the latter type consists of asingle large papillate unit that, by light micros-copy, seems to have a central pore, but cannotbe demonstrated by SEM. However, the twocaudal papillae seen by SEM (Figure 20) couldbe the nep hridiopores, or perhaps they con stitutetwo additional sensory structures.A unique feature of the lorica of Pliciloricusenigmaticus are the seven transverse cuticularridges (Figures 1,13, ri), which are easily seenon the anterior part of the lorica.Higgins-larva (Figures 3, 4) (description based


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10 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGYon 13 specimens in molt) 200-305 /*m long; themouth opening is surrounded by six valves. Thedorsal clavoscalids are broader than those onventral surface; the spinoscalids of the first tworows are fringed and covered with fine hairs. Acollar is followed by a thorax consisting of fiverows of plates formed in an accordion-like man-ner. The lorica has both transverse and longitu-dinal r idges. Th e anterio r margin is not promi-nent; the accordion-like appearance is continuedinto the lorica.Two pairs of hairy sensory setae are present atanteroventral region of lorica. The lorica's sculp-ture (Figure 28) consists of a polygonal patternformed by small, round tubercles; no such sculp-ture is present on the thorax. The toes (Figure9) are short (4 0-5 8 jum), terminally spinous , withthe openings of the presumptive adhesive glandsat the base of spinous portion (Figure 26). Threepairs of setae are present at the posterior end ofthe lorica; two pairs, with an enla rged basal area,apparently have a sensory function; the thirdpair, near the ventrally situated anus, are hollowand rigid.

REMARKS.Some internal structures of P. en -igmaticus are much different than those of Nan-aloricus mysticus. In this new taxon, a glandular,triradiate pharynx bulb is located in the mouthcone when the introvert and mouth cone arefully extruded. The brain (Figures 7, 10) occu-pies most of the introvert.Pliciloricus enigmaticus also differs from Nana-loricus mysticus by the presence of two very largecircular muscles in the abdomen of the formerspecies; one set of muscles is near the edge of thelorica and the other is near the caudal end of thelorica. The epidermal cells that form the loricaappear to be constant in number. The nuclei areplaced in longitudinal rows in the elevated areasof the secondary double ridges of the lorica.There also are a fixed number of cells in thescalids, the pharynx bulb, and perhaps also in th egut. However, eutely appears limited to theseorgans; it is not present in the gonads as mightbe expected. Gametes are more numerous inlarger animals than in smaller ones. Sperma tozoa

are filiform, but often coiled. Oocytes are verylarge; usually only one of the two ovaries isprominent, and a single egg is present at onet ime.One paratypic male from station RH 1833 hada single midventral spinoscalid instead of thedouble-organ, but was normal in all other re-spects.Because all larval specimens w ere in mo lt, cer-tain features of this life-history stage remain un-described.

Pliciloricus dubius, new speciesFIGURES 29-34DIAGNOSIS.Adults 1 6 3 - 1 8 5 pm long; mouthcone with short mouth tube; two elements ofdouble-org an join ed basally. Fifteen third-rowspinoscalids claw-tipped, each with single claw-tip and prominent subterminal accessory tooth.Lorica with single pair of P-flosculi, 1 on eit he rside of ventral midline, and 3 pairs of lateroven-tral N-flosculi. Midventral plica of lorica verylarge and plate-like, with 5 transverse ridges.Secondary trichoscalids very thin and spine-like(easily overlooked); primary trichoscalids very

broad, short , with undulating midventral canalinside. No larvae found.MATERIAL EXAMINED. Type Material: T h eholotype is a young female, 185 /tm long (Figures29-3 4) from station RH 1837; a single paratype,female, 163 /on long, from the same station, waslost during SEM preparation. The holotype(USNM 98559) has been deposited in the Na-tional Museum of Natural History, SmithsonianInstitution. A total of two specimens were ex-amined.ETYMOLOGY.From the Latin dubius (uncer-tain, doubtful); masculine gender.DESCRIPTION.The holotypic female is 185Mm long. Th e m outh con e, 43 /zm long, is com-pletely extended, with a relatively short terminalmouth surrounded by three small teeth (Figures29 , 32). The three sections of the mouth conelack oral ridges. The proximal section attachesto the head by a narrow stalk-like region that


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NUMBER 438 11expands into a prominently bulbous section andcontains eight retractor muscles, each attachedto a small , dist inct apodeme. The second sectionof the mouth cone is enlarged basally and nestswithin the distal limits of the bulbous expansionof the proximal section. Within the bulbous ex-pansion created by the two sections is the phar-ynx. T h e third section is a narrow tub e thatcontains a thin, flexible buccal canal less than 1nm in diam eter . T he re is no evidence for theelements of the mouth cone being telescopic.The mouth cone appears to be re t ractable in tothe head.

A complex, cuticularized ruff (Figure 30) islocated at the base of the mouth cone. It consistsof 14 relatively thick fibers, each ending in asmall cuticular plate and 16 very thin fibers orridges located between the thicker f ibers. The30 fibers terminate in a cuticular r ing si tuatedon the stalk of the proximal section of the mouthcone.

The head ( introvert) has nine rows of appen-dages: one row of clavoscalids and eight rows ofspinoscalids. The eight clavoscalids are short(~50 nm long) and broad (15 fim). All appearbroken. The single paratype lost in SEM prepa-ration had the same type of seemingly brokenclavoscalids, suggesting the possibility that thischaracter is not an art ifact . The second row ofscalids consists of seven leg-like spinoscalids (~65nm long) and the double-organ (~50 / im long).The double-organ (Figures 29-32), as in P. en-igmaticus, consists of two partially fused midven-tral scalids. The basally fused proximal portionis short and rapidly expa nds into a broad middleregion with several stiff hairs. Beyond this regionthe double-organ consists of two unfused rami,each with a row of stiff hairs along the mesialmargins. T he seven remaining spinoscalids of thesecond row of head appendages are more leg-like. Each consists of a proximal element, slightlyenlarged basally and with a small spine arisinghalf its length. The proximal section articulateswith a more elongate, flexible distal section.

The third row of head appendages consists of15 smaller leg-like spinoscalids (Figures 29, 30).

Each of these has a large, double base, whichelongates and then articulates with the first ofthree othe r sections. T he terminal section is thinand pointed; the second section has two smallhairs or spines at its base.The fourth row of head appendages consist of30 spinoscalids; 15 of these long (~70 /tm) andaltern ate with 12 (or 14?) claw-tipped spinoscalids(~50 nm long). The claw-tipped spinoscalids aremore complex than others; the sl ightly bulbousbasal section (~ 10 /im long) is slightly cons trictedin the middle. It is followed by a very short (~2nm), narrow second element. The last two sec-tions are more swollen; the last has a slightlyenlarged midsection from which a single toothprotrudes; the element then terminates with aclaw-like tip. Two distinct points of articulationare evident, one at the distal end of the firstelement and one at the proximal end of the laste lement .

The f if th to seventh rows of head appendagesare very uniform in appearance; each row con-sists of 30 thin, elongate spinoscalids as in allPliciloricidae. Th e eighth row consists of 30 elon-gate spinoscalids, each w ith a basal plate with on eor two small projections. The ninth row has 30highly modified, relatively short spine-like ap-pendages without cusps.The neck of P. dubius is not a constr icted area.It bears seven double and eight single trichoscal-ids (Figure 33); the secondary trichoscalids arevery difficult to see by light microscopy. Theprimary scalids are very broad and relativelyshort (~45 nm). The internal canal running thelength of trichoscalid and containing a singlecil ium appears undulant. The edges of the tr i-choscalid are difficult to see, only a slight, widelyspaced serration pattern is visible. The lowerbasal plate of the double trichoscalids is stronglyornamented, the middle basal plate has a pore,and the upper basal plate is lacking. The eightsingle trichoscalids have indistinct lower basalplates and each appears to have an even lessdistinct upper basal plate.

The cuticle of the thorax is very thin andwrinkled, possibly because of the underlying cir-


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12 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGYcular muscles. The posterior part of the thoraxhas very thin, divergent folds oriented somewhattransversely from midventral to lateral.Th e lorica is a typical Pliciloricus-type with 22plica. The cuticle has a distinctive honeycombsculpturing. Two constrictions are present in theposterior region of the lorica. Th e anterior mar-gin of the lorica has a scalloped pattern formedby two arch-like structures associated with eachof the 22 plica, except for the midventral plica,which has a three-arch configuration. The mid-ventral plica (Figure 34) is more o r less plate-likeas in Nanaloricus. This structure has five narrowcuticular ridges of different lengths. A triangularanal plate is present dorsally and a large analfield of thin cuticle is present on the ventralsurface.A single P-flosculus is located on e ithe r side ofthe ventral midline, near the posterior limits ofthe second abdominal region (defined by the twoabdominal constrictions). Three N-flosculi (Fig-ure 33, nf) are present more laterally on thethird or terminal abdominal region. The N-flos-culi consist of eight micropapillae surro und ing asingle pore from which a free cilium may pro-trude. The position of gonopores, nephridio-pores, and anus could not be determined.

REMARKS.The holotype is a young female.Gametes consist of single clusters of oocytes inthe posterior region of the abdomen. No Hig-gins-larva was found. Th e adult clearly is relatedto P. enigmaticus and, to a lesser extent, to P.gracilis. We postulate that the larva of P. dubiuswill closely resemble that of P. enigmaticus, bu twith a stronger cuticular sculpturing.

Pliciloricus gracilis, new speciesFIGURES 35 , 37-46

DIAGNOSIS.Adult 227 urn long with a verylong mouth tube extending from the mouthcone. Two elements of double-organ with sepa-rate enlarged bases partially fused soon after, notsclerotized more than remaining spinoscalids.Claw-tipped spinoscalids of third row of headappendages without accessory tee th. Th ora x well

defined from lorica. Lorica with transverse con-striction two-thirds posterior, a zig-zag sutureterminally, 22 longitudinal folds, and sculptureonly seen with interference contrast optics. TwoP-flosculi and possibly 2 small N-flosculi present.Higgins-larvae 130-238 nm long, with singlemidventral oral seta on mouth cone; internalmouth arm ature both tri- and h exaradially sym-metrical, with 6 teeth and 6 small stylets nearmouth opening; 6 stylets surround cuticular buc-cal tube; base of stylets join 2 cuticular rings;posterior part of mouth armature continuinginside pharyngeal bulb; 3 pairs of trumpet-shaped placoids in anterior end of pharyngealbulb. Four ventral clavoscalids large, consistingof 2 large segments and a spinous tip; 4 dorsalclavoscalids similar, but more rounded. Appen-dages of second through fifth rows distinctlyspine-shaped, remaining rows of scalids reduced ,scale-like or papillate. Thorax well defined, an-terior 2 rows of plates form a collar. Lorica with2 pairs of three-segmented anterior setae, withmany thin hairs; lorica constricted midway, withsculpture that can be seen by normal light mi-croscopy. Toes straight, shorter than length oflorica, with serrate margin (small mucros) nearbase, articulated with lorica by ball-and-socketjoin t. Anal plate with single pair of stiff, relativelylong, spines.

MATERIAL EXAMINED.Type Material: T heholotype (Figures 35, 37, 38) is an adult male,227 urn long, from station RH 1839. Paratypesinclude 4 larvae from station RH 1839, 5 larvaefrom station RH 1834, 12 larvae from stationRH 1837, and 1 larva from station RH 1833.SEM preparations include 3 larvae (stubs 83, 84)from station RH 1837. A total of 25 specimenswere examined.The holotype (USNM 98560) and 14 para-types, including SEM preparations (USNM98561), have been deposited in the NationalMuseum of Natural History, Smithsonian Insti-tution, Washington, D.C. All other paratypeshave been deposited in the Zoological Museum,Copenhagen.ETYMOLOGY.From the Latin gracilis (thin);masculine gender.


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NUMBER 438 1 3DESCRIPTION.The holotypic male (Figures

35 , 37, 38) is 227 /urn long. The oral cone,including the mouth tube, is 78 fim long. It istotally extended from the head, result ing in anoverall total length of 295 fim. The mouth coneconsists of three sections. The first section (near-est the head) has eight ridges, and a cross-striatedmuscle lies bene ath each r idge and has prom inen tcuticular apodemes distally, marking the l imitsof the first section. The base of the first section,continuous with the pharynx bulb, is narrowlyrestr icted as the apex of a cone; the proximalportion is much wider. The second section alsois conical and has eight rid ges; its base joi ns withthe wide proximal portion of the first section andmay, in a fully retracted mode, fold over the firstsection. T he proximal end , or apex of the secondsection of the cone, is narrowly restr icted. Thethird section, the mouth tube, consists of anextruded portion of the cuticularized buccalcanal that can be withdrawn inside the mouthcone. The inner cuticular l ining of the thirdsection p rotrud es sl ightly (hyperextended?) at thedistal end of the third section.

The l imits of the head and adjoining trunkregion are not well defined. A definite gap doesnot exist between the last rows of head scalidsand the basal plates of the trichoscalids, but be-low the ninth row of head appendages is a hori-zontal cuticular fold, which is interrupted in linewith the trichoscalids of the neck, the area be-tween the head and the thorax. Both adult andlarval stages have a thin unsculptured cuticle inthe thoracic region.

The f irst row of head appendages consists ofeight clavoscalids, ~95 fim long. In the male, theclavoscalids are slightly modified on either sideof the ventral midline; they are thinner andappear more f lexible than the remaining sixmore broadly flattened, apiculate-tipped clavos-calids (Figure 37). Each of the latter clavoscalidsappears to have transverse septa in the form ofseven or eight lines of punctations. A heavilycuticularized supporting axis as in the clavoscal-ids of P. enigmaticus was not observed.The second row of head appendages consistsof nine large leg-like spinoscalids, ~95 /xm long.

Two of these are sl ightly smaller , ~65 fim long,and fused near their separate origins on eitherside of the midline to form the double-organ(Figure 37), which appears no m ore cuticularizedthan the remaining seven separate spinoscalidsof the second row. Each of these seven spinoscal-ids has a bulbous basal region and three otherindistinct sections ben din g at two join ts. A fringeof hairs is on the oral surface of the first elem entand another fringe defines the limits of the sec-ond element .

T h e th ird row consists of 15 leg-like spinoscal-ids ~70 fim long. Each has a double base and aknee-like swelling midway the length of the firstelem ent; no fringe is evid ent, but two stiff lateralhairs are present.The fourth row of head appendages consistsof 30 spinoscalids of two different kinds. Fifteenof these are very long, ~100 fim long, eachconsisting of a long bulbous shaft (30 /am) and athinn er distal segment. T he re main ing 15 spi-noscalids of the fourth row, ~60 fim long, consistof two segments and alternate with the longerspinoscalids. The distal segment is claw-tippedbut lacks any subterminal accessory teeth. Afringe of small hairs is pres ent in the joi nt be-tween the two elements.The fifth, sixth, and seventh rows each have30 long (~70 fim) uniformly filiform spinoscalidswith smooth bulbous bases mounted on smalltr iangular plates. The eighth row of head appen-dages are similar to those on rows 5-7 but arelonger, ~100 /xm, and their bulbous bases havea slight fringe.

T he ninth row consists of round ed basal plateswith only a beak-like appendage, ~3-5 i tm long.Inside the cuticle in this area the re are abo ut 30clusters of glandular cells.The posterior margin of the neck has a row of15 feather-like trichosca lids, each relatively s hort(~50 fim) and th in (~2-4 fim). Seven of the 15trichoscalids are double; the secondary tr ichos-calid is attac hed to the upp er surface of theprimary trichoscalid 1015 fim from the base.The double unit has a common shaft with onelower basal plate as in all Pliciloricidae. Only on eaccessory basal plate is present in the single tri-


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14 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGYchoscalid. The trichoscalids on either side of theventral midline are single; thereafter there is analteration of single and double trichoscalids, withth e result tha t the m iddorsal trichoscalid is asingle one.The thorax appears to be hyperextended, be-cause those specimens of this same genus notsubjected to the osmotic shock of processing infresh water have the row of trichoscalids posi-t ioned just ante rior to the loricated abd ome n,and the whole thorax is retracted inside thelorica, as was the case in Nanaloricus mysticus.Th e tho rax of P. gracilis is divided into five parts;the th ree ante rior parts have the same accordion-like structure as found in all Higgins-larvae.T he a bdom en is divided into two areas. Th emo re prom inent an terior region has a slight con-str iction about midlength. The smaller posteriorregion is capable of being retrac ted into theanterio r region. Both areas have 22 primary and22 secondary vertical folds arranged uniformlyaround the abdomen. The lorica has a f ine, ho-neycomb-like sculpture, which, through refrac-tion of light, makes it appear much more distinc-tive than the remaining cuticularized areas. Theanterior edge of the lorica is scalloped in a pat-tern coordinating with the longitudinal ridges ofthe lorica; it bends outward slightly giving thislorica a distinctive margin. A small posteriorregion of the abdomen is less cuticularized andmay be withdrawn totally or in part into theanterior region; however, the caudal region ofthe lorica has fewer (20) folds. At least a singlepair of P-flosculi and 2-4 small N-flosculi arepresent; these are the only sense organs presenton the lorica. Two or three other pores arelocated terminally and probably are part of thenephr idiopore-gonopore complex.The holotypic male has very small, dorsallyarranged gonads in the posterior region of theabdomen. Gametes consist of a single cluster ofspermatocytes, suggesting that this is a veryyoung male. The buccal canal is very thin, with-out any spiral thickening of the cuticle. Thepharynx bulb is situated close to the anteriormargin of the head and lacks placoids. The eightretractor muscles in the mouth cone are cross-

str iated and easily seen. Th e pro min ent dorsolat-eral muscle complex of other species was notvisible in P. gracilis; only single circular muscles,clearly cross-striated, were observed. No adultfemales were found.Only indirect evidence supports our conten-tion that the description of the following H iggins-larva is that of Pliciloricus gracilis. No specimenswere found molting from the larva of the pread-ult stage as in the case of P. enigmaticus. However ,the larva is assumed to be that of P. gracilis,because two larvae, P. enigmaticus and P. profun-dus, are clearly identifiable with adults and they,like the adult, have similar sculpturing on thelorica. A potential problem exists, because noadult of P. orphanus, only two larvae, was found.The following description is based on a singlefirst instar of the larva (RH 1839.13) and 3specimens prepared for SEM.

Higgins-larvae of P. gracilis (Figures 39-46)are 130-238 / im long. In the single specimenwhere the anterior portion of the mouth conewas fully extended, a single midventral oral seta,six oral stylets, and six oral teeth (Figure 44)were observed.The appendages of the head ( introvert) arearranged in only seven rows. Those of the firstrow consist of eight characteristic clavoscalids,approx imately 43 yum long. Each of the fourventralmost clavoscalids has a smooth, con-str icted base supporting an expanded, broadlyflattened double-segmented blade with a stronglyspinose tip. The four dorsalmost clavoscalids aresimilar, except the two major sections are moreround, not so flattened. The second row consistsof typical spinoscalids, approximately 25 /imlong, six dorsal, four ventral; the two on eitherside of the ventral midline are smaller. The thirdrow consists of six dorsal and eight ventral spi-noscalids ~25 nm long; the ventral ones becomethicker and shorter as they approach the m idline.

The fourth row has 16 spinoscalids, eight dor-sal and eight ventral. The two midventral scalidsare longer (~20 jum) than the othe r 14 (~ 10 -1 5fim). The fifth row has, as in all Pliciloricus larvae,seven spinoscalids, 10-15 /im long, each with ahooked accessory spine projecting from the distal


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NUMBER 438 15end of the basal segment over the tip of theproximal end of the terminal segment. The mid-dorsal spinoscalid of the fifth row has a triang ularbasal segment; the terminal segment is filiform.

The sixth row of head appendages consists ofeight double, short , tr iangular projections, ~4yum long. The double structure is totally sepa-rated at the base and consists of scale-like "pro-toscalids." Four of these protoscalids are foundin a cluster at the mid ventra l line in all Pliciloricuslarvae.T h e seven th row has two kinds of scalids, sevendouble protoscalids alternating with eight verysmall papillae situated on basal plates. The dou-ble protoscalids are only 3-4 pm long an d fusedat the base, forming a "W-shaped" struc ture. T h eprotoscalids of the sixth row and seventh rowalternate, suggesting their pattern of formation.

Between the head an d thoracic region s is alongitudinally r idged closing apparatus, the col-lar (Figures 39, 40, 42), defined by an anteriorhorizontal l ine, middle horizontal constr iction,and posterior line. Beneath each of these linesare circular muscles, which, like three pursestr ings, contract when the head is withdrawn.T he collar appea rs to have i ts own dou ble ventralganglion similar to one more central in the tho-racic region, one in the central abdom inal region,and ano ther in the caudal region of the ab dom en.The collar has four dorsal and three ventralpores, each with a minute hook at i ts anteriormargin .

The remaining, more extensive region of thethorax consists of at least five distinct horizontalrows with about 30 longitudinal r idges. Thisregion is capable of being shortened slightly asthe head is withdrawn, but does not close tightlyover the lorica. The larval lorica consists of amuch thicker cuticle than found on the head orthorax. It has some sculpturing, which is seen asvery fine punctations under light microscopy,and a honeycomb pattern under SEM (Figure46). The lorica has about 20 longitudinal r idges.A transverse constriction is visible, especially indorsal view, in the midregion of the lorica.A distinctive, somewhat inverted cordate analplate is present dorsoterminally. Part of this plate

is visible ventrally as well. Th e an us is positionednear the terminal limits of this plate.Two elongate, straight, r igid toes, ~7l fimlong, extend from the lateroventral region of thecaudal end. About 85% of the length of thesetoes is uniformly wide, approximately 5 fim, a ndhollow; the tip is a narrow, solid spine with apore near the base. Prominent glands, presumedto be adhesive organs, are present at the base ofeach toe. The lateral margin of each toe appearsserrate (small mucros?) for at least half of itslength (Figure 45, mr). The toes appear to becapable of moving both laterally and ventrally.Other appendages of the lorica include paired

setae. Two pair of ventral setae, ~40 /itm long,are located on the anterior margin of the lorica;these are join ted a bout m idlength a nd lack hairs.Two lateroventral setae, ~55 / im long, alsojointed about midlength, have many small hairsnear the base and a few scattered hairs along theremaining portion. The remaining three pairs ofsetae are located dorsally on the caudal region.Two of them have a small basal segment sup-porting the singular elongate element. No hairsare visible. The longer (112 nm ) pair of dor-socaudal setae are located more anteromesialthan the sl ightly shorter dorsolateral pair (~105nm). The third pair of setae, near the anus, areshort (~15 nm), stiff, and without joints.

Several features of the larval internal mor-phology have not been seen in any other species.The buccal canal is lined with cuticle and formsa buccal tube. At the anterior end of the buccaltube are six oral stylets (Figure 44). Posterior tothe stylets, encircling the buccal tube, are a seriesof cuticular structures . T he a nteriormo st of theseconsists of six tooth-like structures with a singleprominent central cusp and two smaller lateralcusps that join with the lateral cusps of eachadjacent tooth. A tooth-like projection extendsposteriorly from each central cusp. Other ele-ments closely articulating with the six teeth in-clude stylet-like structures, the bases of whichextend posteriorly and project into the anteriorportion of the pharynx b ulb. About midway, twocuticularized rings envelop the stylets. Light mi-croscopy has not resolved the critical structure


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16 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGYof these elements no r is their function apparen t.Anteriorly, within the pharyngeal bulb, there isa complex series of cuticular lamellae and threepairs of trump et-shaped placoids associated withthe triradiate lumen of the pharyngeal bulb. Th epharyn x bulb consists of myoepithelial cells and,in the posterior portion, there are three largeglands.A short, cuticle-lined esophagus is present.Th e m idgut appears to contain the band of vesi-cles seen in other loriciferan species, but themidgut does not appear to fill the entire abdom-inal area. The anus is terminal, but its exactposition on the caudal cuticularization is not ev-ident. Adhesive glands appear to extend into thetoes a short distance and are presumed to openvia a small duct near the base of the spinoseterminal end.REMARKS.The adult of Pliciloricus gracilisshares only a few apomorphic characters with P.dubius; among these are eight single and sevendouble trichoscalids and 22 plicae in the lorica.These characters, however, are found also in atleast one additional species to be described later.Although P. gracilis, P. dubius, and P. enigmaticusall have two modified second-row scalids partiallyfused at the ven tral midline, the two componentsof this double-organ are fused to a greater extentin the latter two species than in the more elongatedouble-organ of P. gracilis.Unique to P. gracilis is its mouth cone with along tube, its only slightly sculptured lorica, andthe presence of a single pair of P-flosculi and atleast one pair of N-flosculi.The Higgins-larva of this species has a scalidformula, which differs from either P. dubius orP. enigmaticus, but could be similar to that of anundescribed species found at a depth of 305 moff the west coast of Corsica (Soetaert, Heip, andV incx, 1984).

Pliciloricus orphanus, new speciesFIGURES 47, 55

DIAGNOSIS.Higgins-larva 298 urn long,mouth cone without oral ventral setae, minute

hairs surrounding mouth opening. Internalmouth armature hexaradially symmetrical. Eachof 8 clavoscalids 3-segmented, only lateroventralpair club-shaped, other clavoscalids m ore o r lessspinose. Spinoscalids long (1 5-35 /tm, protoscal-ids triangular-shaped; collar well defined, butirregular. Lorica with 2 pairs of long anteriorsetae, branched without hairs; sculpturing indis-tinct; with mid-transverse constriction. Toesstraight and long (106 /im), pointed terminally.Two pairs of sensory setae present at posteriorend of lorica in addition to a pair of hollow stiffspines near anus; anal plate triangular.

MATERIAL EXAMINED.Type Material: Noadults were found; the holotype (Figure 47) is alarge larva, 298 ^m long, from station RH 1834.One small paratype (Figure 55), ~150 /im long,mounted on SEM-stub 78, is from station RH1839. The holotypic larva (USNM 98562) hasbeen deposited in the National Museum of Nat-ural History, Smithsonian Institution, Washing-ton, DC. The single paratype has been depositedin the Zoological Museum, Copenhagen.

ETYMOLOGY.From the Latin orphanus (ber-eft); masculine gender.DESCRIPTION.The holotypic larva (Figure47) is 298 urn long. Th e m outh cone is tripartitewith the terminal portion slightly retracted teles-copically. Th e thorax and abd omen are exten dedfully. The terminal portion of the mouth conehas six valves, and the mouth opening is sur-rounded by very fine hairs. The internal moutharmature is hexaradially symmetrical, but its de-tailed structure could not be resolved by lightmicroscopy.The appendages of the head (introvert) arearranged in seven rows. The scalids are of thePliciloricus-typc seen in all other larvae of thisgenus, but the first row consists of eight more orless spine-shaped clavoscalids. These three-seg-mented appendages are approximately 45-50nm long. The first two segments of the latero-ventral pair are slightly broader than those ofthe remaining six clavoscalids; the terminal seg-ment is spinous. The basal segment has a fewstiff hairs. The second row of head appendages


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NUMBER 438 17consists of typical two-segmented spinoscalids,~25-40 nm long, six dorsal, four ventral. Theventral spinoscalids are longer and more robustthan th e dorsal ones. No hairs were seen on anyof the spinoscalids. The basal segment of thespinoscalid is triangular in cross-section and hasa slight lateral projection on two lateral surfaces.The spinose terminal segment is more oval incross-section.The third row of head appendages consists ofspinoscalids ~25 fim long, eight dorsal and sevenventral. The fourth row has 14 spinoscalids, sixdorsal and eight ventral; the two midven tral spi-noscalids have very broad basal segments andarticulate with the terminal segments by a well-defined joint. A similar two-segmented spinos-calid is found in the Kinorhyncha. Th e two ven-tralmost spinoscalids of the second, third, andfourth row are nearly fused midventrally, butthey characteristically diverge from the midline.The fifth row has seven spinoscalids, each with ahooked accessory spine on the basal segment,similar to that noted for the larva of P. gracilis.The middorsal spinoscalid of this same row hasa large triangular basal segment with a promi-nent filiform proximal segment (Figure 47 ). Thesixth row of head appendages consists of eightdouble protoscalids; each projection has a serru-late margin and central keel that continues be-yond the margin as a very small spinose tip, acondition most prominent in the dorsal protos-calids. One of the diagnostic characters of thegenus Pliciloricus is the presence of four clustersof protoscalids found along the midventral line.In P. orphanus, these four protoscalids aresmaller (5 /an) than the rem aining 12 protoscal-ids (7 /um) of the sixth row.

The seventh row of appendages consists ofseven double protoscalids alternating with 8 sin-gle papillae; each papilla has a small terminalspine. Thes e d ouble protoscalids are mo re or lessfused basally, forming a "W-shaped structure.One double protoscalid is middorsal, with a sin-gle papilla located lateral to it.The collar is not so regularly folded as in P.gracilis and lacks collar pores. The thorax has

five horizontal rows of 15-30 plates, separatedby distinct ridges in the m anner of an accordion.The first row of thoracic plates has 15 ridges,similar to the pattern of folds in the collar. Thelast row of thoracic plates has about 30 ridgesthat are continuous with those of the lorica. Th elast row of thoracic plates on the ventral surfaceis nearly divided into two sepa rate rows of plates,giving the appearance of an ex tra "sixth" row ofplates ventrally, but only five rows dorsally. Thelarval lorica has a very thick, unsculptured cuticlewith ~20 primary longitudinal ridges beginningat its anterior edge and e nding at th e anal plate.Ten secondary ridges are present ventrally, butthey extend just short of the middle of the lorica,where a transverse constriction is visible. A dis-tinctive triangular anal p late is present dorsoter-minally. Th re e additional pairs of cuticular platesare present lateral to the anal plate; the anus isterminal on the anal plate (Figure 4 7, an).Two long, rigid toes (~106 um long) extendfrom the lateroventral region of the caudal end.About 70% of the length of the toes is hollow(~8 ^m wide); the other terminal 30% of thelength narrows to a solid spine. Two prominentglands are present in the posterior abdomen atthe base of each toe.The two anterior pairs of lorical setae arebranched; each begins with a swollen base, whichgives rise to a mesial ramus; the lateral ramuscontinues, then branches again in a similar fash-ion, resulting in three units (Figure 47, lsa). Thelateroventral setae also have a large base, buthave only a slight branch coming off the prim aryelement. No hairs are visible on any setae.The posterior three pairs of setae are similarto what have been described for P. gracilis, butthe ball-and-socket joints of the dorsolateral pairare very large and project beyond the lateralmargins of the lorica at the caudal end.REMARKS.The larva of P. orphanus is verylarge and is somewhat similar to the Nanaloricuslarva in that both have more or less spine-shapedclavoscalids. The anterior midventral setae arestiff and could have a locomotory function as inthose of th e Higgins-larva of Nanaloricus mysticus.


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18 SMITHSONIAN CONTRIBUTIONS T O ZOOLOGYThe head appendage formula (spinoscalids andprotoscalids) is similar to that of other species ofPliciloricus, especially P. gracilis. The toes clearlyare of the Pliciloricus-type.

Pliciloricus profundus, new speciesFIGURES 48-54

DIAGNOSIS.Adult 200 /tm long. Largemouth cone (48 pm long) without mouth tube.Eight clavoscalids prese nt, m idventral clavoscalidspinose; remaining clavoscalids very broad, es-pecially in the middle of four distinct segments,distalmost segment spinose. Two short, adjacentsecond row spinoscalids perhaps only partiallyfused to form a double-organ. Fourth row ofhead appendages consists of 15 long, filiformspinoscalids alternating with 15 short claw-tippedspinoscalids. Lorica with single pair of P-flosculi.Secondary trichoscalid of 7 double trichoscalidsnearly same size as primary trichoscalids. Mid-ventral plicae of lorica differ only slightly fromother 20 plicae.Higgins-larvae 16 8-2 32 yum long, slen der.Mouth cone with prominent midventral oral seta.Terminal oral field with 6 valves and hexaradi-ally symmetrical internal mouth armature. Firstrow of appendages consisting of 8 clavoscalidseach with 2 laterally compressed segments andterminal spinose segment; second and third rowsof appe ndag es with fringed spinoscalids minutelydouble claw-tipped; protoscalids with small lat-eral teeth. Collar symmetrical, with 7 oval sen-sory spots. Lorica with 2 pairs of filiform anteriorsetae each with a row of widely dispersed hairs;2 pairs of sensory setae at posterior end of loricaand pair of hollow stiff spinose setae near anus,all without hairs; surface of lorica pustulate . Analplate dorsal, rectangular, joined to lorica by anindistinct heart-shaped plate; lateral anal plateon either side of anal plate. Toes long (75-107/im), spinose.

MATERIAL EXAMINED.Type Material: T h eholotype (Figure 48) is an adult male, 200 ur nlong, from station RH 1833. Paratypes include7 larvae and 1 larval exuvium from station R H

1833 and 40 larvae from station RH 1834. SEMpreparations include 1 decapitated larvamou nted on stub 84 and 1 comp lete larvamounted on stub 85 (Figures 50-53), both spec-imens from station RH 1837. A total of 51specimens were examined.In addition to the holotype (USNM 98563), 3paratypic larvae (USNM 98564), including theSEM materials, have been deposited in the Na-tional Museum of Natural History, SmithsonianInstitution, Washington, D.C. All other para-types have been deposited in the Zoological Mu-seum, Copenhagen.ETYMOLOGY.From the Latin profundus

(deep); masculine g end er.DESCRIPTION.The holotypic male (Figure48) is 200 nm long. The mouth cone (48 nm ) iscompletely extended and the ruff on the head iseverted. The three sections of the mouth coneare similar to those of P. enigmaticus. The firstsection (nearest the head) is large and expandsin a cup-like man ner at its jun ctio n with th esecond section. Within the first section are eightretractor muscles, each attached to an indistinctapodeme located at the distal limits of the sec-tions, where it appears to telescope with thesecond section. The second section has eight oralr idges, which extend to the third section. Thethird section lacks a mouth tube; the internalbuccal canal is very thin and apparently cannotbe extrude d as in Nanaloricus. The pharynx bulbis glandular and may not have a myoep ithelium.

The ruff consists of 15 fibers attached to aterminal ring ; the ruff is eve rted in the ho lotypeand can be seen as an external cuticular structureat the anteriormost part of the head. The r ing-shaped structure has a very small diameter andsurrounds the basal part of the mouth cone. The15 fibers attach to the cuticular ring and are notcoiled at the free end, which is situated betweenthe bases of the eight clavoscalids. As in all specieswhe re it is prese nt, the ruff probab ly functionsas a kind of sphincter in the extrusion and with-drawal of the mouth cone as mentioned in thedescription of P. enigmaticus. The ring-shapedstructure marks the limit beyond which the


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NUMBER 438 19mouth cone cannot be extruded. I t is obviousthat the mouth cone cannot pass through thesmall diameter of the r ing unless the r ing can beenlarge d. T hu s, i t acts as a kind of closing appa-ratus for the mouth cone.The head ( introvert) has the typical nine rowsof appendages. The first row has eight clavoscal-ids; the two ventralmost are narrow, more spine-like; the two remaining clavoscalids, especiallythe dorsal ones, are very broad, laterally flat-tened scalids. The dorsal scalids have three dis-tinct segments in addition to a spinose tip.

The second row of head appendages consistsof seven very long, leg-like spinoscalids (110fim long), and short (~50 /tm long) spinoscalidsmay be only partially joine d along the ventralmidline; the bases and the t ips are s eparated , a ndthe unsegmented double-organ appears to havea thin cuticle, quite different from the double-organ of P. enigmaticus. The seven other spinos-calids of the second row each have two distinctsegments in addition to a small basal stalk. Theproximal segment, largest of the two segments,is broad with two small, stiff hairs along theanterior margin. The distal segment is spinose.T he third row of appen dage s consists of 15 small(70 /an) leg-shaped appendages, each withslightly enlarged double base. About one-thirdthe length of each appe ndag e th ere is a tub er-cular joi nt with a stiff hair projec ting from itsside. The fourth row of appendages consists of15 long spine-shaped scalids (100 /an) alternatingwith 15 short claw-tipped scalids (45 fim). Allappendages of the fourth row consist of twosegments. The terminal segment of the claw-tipped spinoscalids is minutely serrate d. T he nextthree rows of appendages are nearly uniform,with each row consist ing of 30 non-segmentedspinoscalids. The 30 spinoscalids of the eighthrow possess a basal plate that supports the finelyserrate filiform single element. The ninth rowconsists of 30 very short, beak-like spinoscalids,~10 /*m long.

The neck is moderately extensive; the l imitsof the thorax are marked by a constr iction. Thelimits of the head are less distinct. The seven

double trichoscalids have well-developed lower(tpi) and middle basal plates (tp 2) . T he upperbasal plate (tp3) is lacking. Th e larg e midd le basalplate has a distinct spine. Both secondary andprimary tr ichoscalids are serrated, and both ele-ments are nearly equal in length. Th e eight singletrichoscalids lack middle basal plates and eachupper basal plate has a tooth-like projection.T he thorax is partly withdrawn into the loricaand is not entirely visible; however, there is onlya sl ight separation of the lorica and thorax. Thelorica lacks sculpturing; its midventral plica dif-fers only slightly from the other plicae, and themiddle of each plica is not elevated. The poste-

rior part of the lorica has a thinner cuticle thanthat in the ante rio r regio n. It is sepa rated fromthe latter by a zig-zag line. A single pair of P-flosculi is pres ent ven trally. Tw o lateroca udalspines, each with a small basal pore, m ay be p enilespines. Sperm are filiform with a slightly coiledhead region.The description of the Higgins-larva was facil-i tated by the large num ber of specimens, 49 total ,most in excellent condition. The smallest speci-men (130 fim), in a retracted configuration, hadan ovoid structure attached caudally; this could

be a remnant of the egg cuticle of the newlyhatched first stage larva. No differences in theexternal structure were noted from the smallest(130 /an) to the largest (232 fim) larva.The typical Higgins-larva of P. profundus (Fig-ure 49), i l lustrated from specimen number RH1834.72 , is 224 fim long with toes 105 fim long.The mouth cone of the glycerin-mounted speci-men is tripa rtite and the term inal p art is slightlyretracted telescopically. The terminal portion ofthe mouth cone has six pincer-like valves. Theinternal m outh a rma ture is hexaradially sym-

metrical and superficially resembles the mastaxof a rotifer . The exact structure of the armatureis beyond the resolution of the light microscope;only a limited amount of detail could be seen.The anterior portion resembles an umbrella withsix ribs; the umbrella surrounds six internal sty-lets that are joint ed. T he posterior portions ofthese stylets are e mbe dded in the ovoid p harynx


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20 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGYbulb, where each term inates as a furcate base. Inthe m iddle of the whole structure there is a thincuticular lining indicating the buccal canal. Thebuccal canal continues through the pharynx bulbas a triradiate lumen. The pharynx bu lb appearsto consist primarily of glandular tissue. On theposterior part of the mouth cone, there is a singleprominent midventral seta (Figure 49 , ms).Th e appendages of the head (introvert) are ofthe Pliciloricus-type, but they appear to be ar-ranged in only six rows. The first row of appen-dages consists of the eight clavoscalids, ~35-40fim long. The four ventral clavoscalids areslightly narrower than the four dorsal ones; oth-erwise, all are broad, flat appendages with twosegments and a spinose tip. At the base of the tipthere is a fringe of hair. A few hairs are presentat the junctions of the othe r segments, but thesecan be seen only by SEM.The second and third rows of appendagesconsist of the typical 15 2-segmented spinoscal-ids, 30-40 fim long. The seven dorsal scalidsappear narrow and somewhat inflexible; theeight ventral are more robust and have smalldouble-claw tips. Th e proximal segments of theseappendages, particularly those on the ventralsurface, have a broad base. The joint betweenthe two segments is very distinct. The lateraledges of the proximal segm ents have a small keelwith minute hairs. On the distal segments, thehair is arranged in a comb-like structure. Thefourth row of appendages is similar to the fifthrow in P. gracilis and P. orphanus, thereby sug-gesting that the Higgins-larva of P. profundusmay lack one of the more anterior rows, perhapsthe fourth row, but this is difficult to assess. Thelast three rows, 4, 5, and 6, are similar to otherPliciloricus-larxa. The seven scalids of the fourthrow have triangular or beak-like proximal seg-ments. Both the single middorsal and the twomidventral appendages have a triangular proxi-mal segment with two sharp edges and are cov-ered uniformly with minute hairs. The tip of themore or less triangular appendage is spine-like.The joint between the two segments is hiddenbelow the spine. The distal segment is rhomboi-

dal in cross-section, with four rows of hairs cor-responding to the four angles.Th e fifth row of appendages consists of eightprotoscalids. The two midventral protoscalidsare very small, and the two pairs of middorsalprotoscalids are large, each with two elementsand a fused base. Th e sixth row has seven doub leprotoscalids alternating with eigh t small papillae,each with a basal plate. The triangular protoscal-ids have serrated lateral surfaces.Th e collar (Figures 49-51 ) consists of 48 folds.Seven presumptive sensory spots are present, asin P. gracilis. Four such spots are dorsal (two nearthe dorsal midline, two more lateral) and three

are on the ventral surface (one midventral andtwo lateral). Four folds in the collar corre-sponded with a single plate in the thorax; thiscould indicate that th e collar is homologous w iththe neck area of the adult. These sensory spots(P. profundus) or oval pores (P. gracilis) could beseven prototrichoscalids, but this is only specu-lation. The collar is a closing apparatus withthree circular muscles as mentioned under thedescription of P. gracilis.The thorax hasfivedistinct ho rizontal rows ofplates; the first row consists of 13 plates, thesecond and third rows each have 14 plates, andthe fourth and fifth rows each have ~20 plates.Th e lorica has ~2 0 longitudinal ridges. A trans-verse constriction divides the lorica about mid-way. A circular muscle is present beneath thecuticle at the site of the constriction. Sculpturingof the lorica could be seen only by SEM. Thecuticular surface of the lorica is densely papillatein contrast with the honeycom b-structure patternmade up of this same material in P. gracilis. Thethick cuticle of the dorsal lorica term inates ~ 10 -15 nm from the caudal end; the caudal end hasa distinctive rectangular anal plate and two lat-eral accessory anal plates. Th e anal plate isunitedwith the an terior portion lorica by a more o r lesscordate cuticular structure . Th e anus is terminal.

Two very long, straight toes (Figures 49, 50,53) (106 nm long) originate ventrolaterally nearthe caudal margin of the lorica and bend ven-trally, away from the animal's body. About 65%


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NUMBER 438 21of the length of the toes is of uniform width (3-4 nm) and hollow; the tip is a narrow solid spinewith a large pore near its base. A triangular basalplate (Figures 53, 54) covers the insertion of thetoes on the ventral side of the lorica.

The two pairs of ventral setae originate at theanterior margin of the lorica. These are unseg-mented, long and filiform (~55 ftm) with 5-6long hairs projecting from the surface. Severalvery small hairs were apparent by SEM. Theremaining three pairs of setae are located cau-dally; none have any evidence of hairs, but SEMexamination showed that three pairs have a ser-rated edge. The two dorsal pairs (~75 /im long),have a ball-and-socket articulation with thetrunk; the third pair (~25 nm long), located oneither side of the anus, are stiff and appear tohave a terminal pore.REMARKS.Pliciloricus profundus, based on itslarval characters, is closely related to P. orphanus,and to a lesser extent P. enigmaticus and P. gra-cilis. The presence of only six rows of headappendages is unique to P. profundus. The adultis notable in that its lorical structure is not sospecialized as the other species of Pliciloricus andthe double-organ is only slightly fused. Thesetwo characters suggest that P. profundus may bemore closely related to the genus Rugiloricus,especially R. ornatus; however, the double tri-choscalids and the typical P/id/oncws-larva clearlyindicate that P. profundus belongs to the genusPliciloricus.

Rugiloricus, new genusDIAGNOSIS.Adults 115-264 pm long, with a

small mouth cone. Male with 4 large dorsal cla-voscalids and 4 small ventral clavoscalids or with8 uniform clavoscalids as in female. Glandular

pharyngeal bulb without armature. Fifteen singletrichoscalids on neck. Separation of thorax andloricated abdomen not well defined; lorica with30-60 longitudinal folds, single transverse con-striction about midway from anterior margin;cuticle very thin, without sculpture, without flos-culi or with single pair of P-flosculi; posteriorend of lorica may be constricted abruptly into around pedicle-like structure with 2-4 small po-res. The anus-gonopore complex appears dor-sally displaced.

Higgins-larvae 114-345 /an, with a mouthcone consisting of three telescopic segments. Ex-ternal armature of the mouth cone hexaradiallysymmetrical, armature consisting of 6 primaryteeth and 6very small accessory teeth, 12 doubleoral stylets and 6 leaf-shaped structures; buccaltube very short, without internal armature; pha-ryngeal bulb long, without placoids. Eight cla-voscalids, with a "swollen" tip, without hair; first2 rows of spinoscalids elongate and pointed, re-maining rows strongly modified; middorsal spi-noscalid in last row peg-shaped. No collar areaapparent. Thorax with 5-6 rows of plates. Loricawith both longitudinal and transverse folds; with2 paris of anterior setae, each with many small,stiff hairs; only 2 paris of stiff posterior setae,each with swollen base; no flosculi observed; toesshort, anal plate located ventrally. Note: In twoof the three species of Rugiloricus, typical Hig-gins-larvae were not observed, only aberrant lar-vae (postlarvae?) without toes on the abdomenand without lorical setae were found.

TYPE-SPECIES.Rugiloricus cauliculus, newspecies.COMPOSITION.Rugiloricus carolinensis, newspecies; R. cauliculus, new species; R. ornatus,new species.

ETYMOLOGY.From the Latin ruga (wrinkle)plus lorica (corset); masculine gender.

Key to Adults ofRugiloricus1. Lorica without flosculi; anal cone present; mouth cone very small (~16

nm long) with 4-6 oral stylets (or papillae). R. cauliculus, new species


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NUMBER 438 23than in other Pliciloricidae. The first row con-tains the typical eight clavoscalids, all nearly thesame in appearance and size, al though they arestill wrinkled from the molting process; they areunsegmented and have a small spinose t ip. Thesecond row of head appendages consists of nineelongate spinoscalids; the two spinoscalids adja-cent to the ventral midline are not fused to forma double-organ. The third row consists of ~15similar, but smaller spinoscalids. The 30 appen-dages of the fourth row are more spine-like asare those of the next four rows. The ninth rowconsists of 30 small beak-like scalids.

T h e neck is extens ive and set off from thehead and thorax by constr ictions. In addition, aslight constriction is prese nt jus t abo ut th e inser-tion of the 15 single trichoscalids. The trichos-calids ar e small (~3 0 /xm); seven o f them (thesecorrespond with the double tr ichoscalids in Pli-ciloricus) have typical well-defined lower basalplates, the other eight ( these correspond with thesingle trichoscalids in Pliciloricus) have poorlyformed lower basal plates. Upper basal plates,each with a distinct spine, are situated slightlyabove the lower basal plates. Middle basal plateswere not seen.

T he thorax is without sculpture, and the cuti-cle is very thin, revealing 15 underlying cross-str iated muscles. These muscles attach near theanterior and the posterior l imits of the thorax.The lorica has about 30 longitudinal folds,corresponding to the plicae in Pliciloricus. O n etransve rse constriction is pres ent abo ut midwayfrom the distinctive anterior margin of the lorica.The constriction is formed by a system of circularmuscles within the abdomen. The posterior endis not constric ted abr upt ly, but a trans verse foldis pres ent; tw o ventrally situate d P-flosculi are

near this transverse fold. Two very small poresare situated laterally and slightly more posterior;two others are near the ventral midline. Theposteriormost region has a large anal field orplate with two distinct pores (gonopores?). Closeto the edge of the anal field there are two verysmall pores; these could be the nephridiopores.Th e anus was not easily observed , but the rectum

was seen terminating dorsally in the vicinity ofthe anal field.We suspect that the adult animal inside thelarval cuticle is a young female, because the twoclusters of very large gametes are present in thegonadal t issue, and because the spermatocytesand spermatids observed in other species of Rug-iloricus are much smaller . The larval exuviumhas all the characters of Higgins-larvae from thisgeographic area. Assuming the exuvium is thatof a larva and the molting animal is an adult, apostlarval stage may not be present in the life-cycles of/? , carolinensis.The Higgins-larva of R. carolinensis is very

different from the other larvae described in thispaper, and without the holotypic specimen, anadult within the larval exuvium, it would havebeen difficult to relate the immature stage to thePliciloricidae. T he larvae varied from 114 -34 5nm in total length. Length-frequency measure-ments suggest that as many as five instars mayexist, but such data ar

higgins y kristensen 1986 loricifera

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