;; ij Il 1I U it li ii H 13 u Autor: t-i ij ii 11 iil u li U Titel: H I] Il !J Band: I~ Ii fj iI [i s. 181 - 201. li 13 U li U It ii I,i Ii U t-i il il ii 11 il 11 li Il il lil U Ii il 1I l~ li Ii vörhanuen 1I 1,1 ti U n u 1I ii It 11 u I1 U li 1.1 it jj u ii u n 11 ii 11 H.l l,I II n il ii li ii ii U Ii U li 11 I] II !l !:! 1'1 I1 6 ?e> O$-15k~w'rl~1i. 180 T.A. Platonova& L. V. Kulangieva: Marine £noplido- ZOOSYST. ROSSICA Val. 3 @ Zoological Institute, Sl.Peter~ 1995 pharynx aod proposal of two new families. Zool. Tchesunov, A. V. 1991. On the slruclure of thc cephaJic Zhurn., 69(8): 5-17. (In Russian), culiclc in frcc-living ncmatodcsof thc famHy Linho- - Tchesunov, A.V. 1990b. Long-hairy Xyalida (Ncma- mocidae (Nemaloda. Chromadoria, Siphonolaimo- loda, Chromadoria, Monhystcrida) in thc Whitc ideaL Zoo!. Zhurn., 70(5): 21-27. (In RussianL The phylogeny and classification ofthe phylum Sca: ncw spccics, new combinations arid s~atusof Ih~ genus Trichotheristus. Zoo!. Zhurn., 69(10): 5-19. Reeei."ed 27 Mo)! /99J (In R!JssianL Cephalorhyncha
A.V. Adrianov & V.V. Malakhov
Adrianov, A.V. & Malakhoy, V. V. 1995. Thc phylogcny and c1assification of thc phylum Cephalorhyncha. Zoosystematica Rossica, 3(2),' 1994: 181-201.
The phylum Ccphalorhyncha is a laxon including headproboscis worms: Priapulida, Loricifera, Kinorhyncha, Nematomorpha. The body of all Cephalorhyncha is divided into proboscis("" introvert) and trunk. The introvert is capable of invaginatiog iolo the trunk a~d is subdivided ioto the mouth q>ne, ccotral pari wirh scnsory-16comolory scalids, and.neck region. The central nervous system consist~ of nerve ring localcd in thc introvert al the base of mouth cone, and ventral cord., The cephalorhynch worms of Middle Cambrian Burdgcss Shalc fauna are reviewed. Anca/agon and Fie/diaarc the most' primitive cephalorhynchs. Their proboscis is l'!0t able to jnvaginate completcly. Anca.
" /agon and Fie/dia could be included into aseparate subphylum Protoccphalorhyncha. Anether subphylum, Eucephalorhyncha •.is characterized, by the introvert bcing able 10 invaginate into the trunk. Subphylum Eucephalorhyncha i'nC!udcs the c1asses Louiscllida (Middle Cambrian only), Priapulida (with Middle Cambrian Oltoia and SelkirJcia, Carboniferous Priapulites and several recent genera), Loricifera (considcrcd to bc neotenie group), Kinorhyncha, and Nematomorpha, the most advanccd group, wherc only larvac retain the structure of headproboscis worm. Diagnoses of Ihc phylum Cephalorhyncha, ßew subphyla Protocephalorhyncha and Euccphalorhyncha, and all c1asses and orders of extinct and extant ccphalorhynchs are prcscnlcd,
A. Y. Adrianov. Institute 0/ Marine Bi%gy, YladivostoJc 69004 J, Russia.
,V. Y. MaJak.hov, Department oflnvertebrate Zo%gy, MosL"OW Stafe Utliversily, Moscow J 19899, Russia.
I. Historie background phyluin Aschelminthes is an unnatura', assem- blage of heterogeneous groups. Thus, discuss- About120 yeaeS ago Pagenstecher (875) not- ing the origin of nematodes, Chitwood & Chit- ed that the phy1um Vennes (Wonns) had be- wood (950) noted: "The most noulble char- eome an artificial group that included every- acteristi6 of all discussions about the ki'ndred thing that did noi belong to other phyla of the ties of nematddes from the time of Huxley 10 animal kingdom. Sinee that time, the higher the present was that the eoncept of Nemalhel- classifieation of theAnimalia hasbeen signifi- minthes ... has never been accepted by analo- eantly changed. The old phylum 'Vermes, mists, although, judging by appearance, it has which was a kind of zoologieal "dumping entered into zoologicalliterature". Because of ground", was abolished. Some time afterwards, that several attempts to divide Aschelminlhes the remainder of the fonner Vennes was united jnto Qatural groups have been made; ~ome of in artifieial high ta"on - the phylum named them are reviewed below. Asehehninthes (pseudoeoelomate worms) 'Grasse & al. (961) divided pseudocoelomate (Grobben, 1908) or Nemathelminthes (round worms into several phyla: Nemathelminthcs wonns) (Gegenbauer, 1859, cited after Chit- with cIasses Nematoda and Nemato~orphH; wood & Chitwood, 1950). It eomprised ,the Nematorhyncha with c1asscs Kinorhyncha and following groups: Nem~toda, Gastrotrieha, Gastrotricha; and Rotifem wilh a single dass Rotifera, Aeanthoeephala, Nematomorpha, Rot~toria. Classcs Priapulid,1 and Acnntho- Priapulida, and Kinorhyneha. . cephala were assigncd as groups of uncertain Neveriheless, many zoologisls feit that the taxonomie position. In Brien's (1961) concepl, 182 A. V. Adrianov& V.V. Ma/aJchov: On CephoJorhyncha -WOSYST. ROSSICA Val. 3 ZOOSYST. ROSSICA Val. 3 .A. V. Adrianov & V.V. Malakhov: On Cephalorhyncha Ihe phylum Nemathelminthes was eXlended tn mnrphnlngy, mieroscnpic anatnmy and ultra- 183 incIude three cIasses, Nernatoda, Nematornor- structure of the reeent headproboscis worrns: The introvert of all cephalnrhynchs is a unique portion, which, in turn, is incapable of being pha, and Acanthncephala, while nther pseudn- priapulids (Land, 1968, 1970, 1982, 1985; Pnr structure found only within headproboscis completely withdrawn inln the trunk. The cnelnmates were cnnsidered as separale phyla. & Bromley, 1974; Salvini-Plawen, 1974; Mnr- y worms. Because nf the presence nf the central mouth cnne is armed with 10 anteriorly direcl- Andniss 0976} favnured uniting nnly twn se, 1981; Stnrch & al., 1989, 1990, 1994; nervous syStem (circular brain), sensory struc- ed teeth, while the centra! prnboscis bears nu- elasses, Nematnda and Nematnmnrpha, in Ne- Higgins & Stnrch, 1989, 1991; Adriannv & al., tures, and fenninal mouth, it differs consider- merous irregularly arranged and posterinrly mathelminthes. Snme authnrs, relllining the 1989c, 1992; Adriannv & Malakbnv, 1991, ably from proboscis-llke organs of nther worms directed scalids. In contrast to the proboseis, phylum Aschelminthes, raised the rank nf snme 1994}; Inrieiferans (Kristensen, f983, 1991 a, (proboseis nf turbellarian-kaliptnrhynchs; fix- the annulated trunk is covered with numerous, groups In the level nf independent phyla, fnr 1991b; Higgins & Kristensen, 1986; Krislen- atory apparatus of acanthncephalans; raptorial thin setae, also arranged irregularly. There are example, Acanthocephala (Skryabin & Schultz, . sen & Shirayama, 1988; Adriannv & al. , 1989a}; probnseis nf nemerteans; eversible pharynx nf no speciaJized introvert retractors, they are 1931; Hyman, 1951; Beklemishev, 1964) and kinnrhynchs (Neuhaus 1988, 1991; Adriannv some polychaetes). The introvert nf Cephalo- functionally replaced by Inngitudinal museles Priapulida (Kaeslner, I 965} . & al., 1989b, 1990a, 1990b; Adriannv & Ma- rhyncha is the true eversible head. nf the dermomuscular tube bnrdering the volu- Being disappninted in their anemps tn find lakhnv, 1990, 1991a, 1991b, 1991c, 1991d, minous body cavlty. As in Pieldia, the absence phyletie relatinnships within Aschelminthes, 1994; Kristensen & Higgins, 1991); nematn- 3. Mnrphology of fossil cephalnrhynchs of any retractors correlates with inabillty of the Chitwnnd and Chitwnnd (950) propnsed the mnrphs (Zapntnsky, 1971, 1974, 1975; Eakin proboscis to be withdrawn completely. Anca- raising nf tbe ranks nf al1 classes tn indepen- & Brandenburger, 1974; Bresciani, 1991). The initial bodyplan common fnr all known lagon is supposed to be an obligate predator. denl phyla. This view has been accepled in The cnmparative-mnrphnlngieal analysis nf cephalorhynchs was formed within Middle The structure of the anterior teeth and the snme mndern zonlngieal textbnnks (e.g. Barnes fnssil cephalnrhynchs is mainly based nn Ihe Cambrian headprobnseis wnrms (Figs I, 2). absence of gut contents suggest a carnivorous & al., 1988). It shnuld be nnled lhal such papers dealing with the Middle Cambrian fauna The Cambrian Fieldia and Ancalagnn are diet (Conway Morris, 1977). approach dnes nnt snlve the problem nf the Asc- nf Ihe Burgess Shale (Walcnn, 1911a, 1911 b, characterized by the most primitive segmenta- Louisella is the longest of the Cambrian ce- helminthes. As a result nf Chitwnnd & Chit- 1911c, 1912, 1931; Cnnway Mnrrls, 1977). tion nf the body within known cephalorhynchs wood's view, nowadays we have at Jeast 8 (Wa1cnn, 1912; Cnnway Mnrris, 1977}. A more phalnrhynchs (up tn 20 cm) with a combinalion separale phyla nf uncenain phyletic relatinns: or less separated probnseis is still capable nf nf plesiomnrphic and apomorphic features. Nemalnda, Gastrnhicha, Rotifera, Acanthoce- 2. The bodyplan nf cephalnrhynch wnrms only partial inversion. The only invaginable within fnssi! headproboseis worms (Wa1coll, phala, Nematnmnrpha, Kinnrhyncha, Priapu- pnrtion is the mnuth cone, capable of being 19I1b; Cnnway Mnrris, 1977). The former Iida, and Lorieifera. Traditinnal1y, any phylum has tn be charac- cnmpletely retracted into the central probnseis. characters include: soft-bodied cylindrieal In the beginning nf this century, the Russian terized by a speclfic bndyplan (type nf nrgani- Fieldia isa marine soft-bodied burrower of 4-5 cm trunk with elastic integument; well-developed zonlngist Schepntieff (1907) drew attention tn zation), common only for the representatives length, with a cyllndrical trunk and weakly dennomuscular tube; spacious body cavity. In separated probnseis region (Fig. 2). The short remarkable similarities nf kinnrhynchs and nf this group. The bndyplan of cephalnrhynchs contrast to the above mentioned worms, the is the fnl1nwing (Fig. I). inversible mouth cnne is armed with approxi- gordian larvae, botb baving a spiny eversible bndy nf Louisella is slightiy compressed dor- mately 30 anterinrly directed spines arranged proboscis. Later, on thc basis of comparison of The bndy nf al1 cephalnrhynchs Is divided soventrally, the trunk being characterized by in a single terminal eircle!. The central portion Ihe larvae nf priapulid Halicryptus with adult into two main regions: proboscis (=head) and numerous concentric zones of minute spines nf proboseis bears irregularly arranged unifnrm abdnmen (=trunk). In all recent cephalo- separated by unarmed rings. Apparentiy, Ihe kinnrhynchs, Hammarsten 0913, 1915) as- conical papillae - scalids. The trunk is also. sumed that kinnrhynchs were the nearesl rela- rhynchs (al leasl larval stages), Ihe eversible weil differentiated introvert is capable of being head, or introvert, can invaginate into the trunk equipped with numerous cnnical papillae, nr lives nf priapulids. Based nn the presence nr spines, similar tn thnse nf the probnseis. There cnmpletely invaginated (Fig. 3). The Jong nr neck area. The Inlrovert conslitules Ihe first absence nf distinct proboscis, Lang 0953} di- are nn visible annulatinns of the trunk. The mouth cone is arrned with minute 8nterior and segment nf the bndy. The radially symmelrical vided al1 Aschelminthes intn twn phyla: Aryn- spines of the anterinr trunk are arranged in oral spines, both sets arranged quincunxially in chnhelminthes with elasses Rntatnria, Nematn- proboscis is also. subdivided inlo several sub- several concentric, rings, while in the centtal about 25 nblique rows (Cnnway Morris, 1977). da, Gastrotrieha, Nematnmnrpha; and Rhyn- regions: eversible or ProtrusibJe mouth cone and posterinr portions the spines are arranged Similar to the condition fouod in the true pri- chnhelminthes with elasses Kinnrhyncha, Pri- hearing anteriorly-directed styles or leeth; spheri- irregularly. The dermnmuscular tube is well- apulids, the base nf the mouth cnne is bordered apulida, Acanthncephala (+ fnssil Ottoia}. cal eversible central portion armed with sen- develnped. There are nn specialized retractnr by a single e1relet of 40-50 anleriorly directed Cnnway Mnrris (977) expressed an npininn sorial-Iocnmotory scalids direcled pnsteriorly; muscles in the vnluminnus body cavity. The gut long eircumoral scalids. These scalids, some- about elnse phyletic relatinnships between acan- and neck area (snmelimes named Ihorax). The just behind the terminal mnuth is preserved as what f1anened and with a thickened leading thocephalans, priapulids, kinnrhynchs, and ne- mouth cnne is terminated by the moulh npening an nvoid reflective mass deslgnated as muscular edge, are similar to anteriorrnost scalids of mo- matnmnrphs. Final1y, Malakhnv (I980) estab- fol1nwed by fnre-, mid- and hindgut with ter- pharynx (Cnnway Mnrris, 1977}. The accu- dern kinnrhynchs and lorieiferans. This cirelet Iished a new phylum Cephalnrhyncha uniting minal or subterminal (ventral) anus. mulatinn nf sediment within the midgut suggests is fnllowed by numerous posterinrly directed three pseudocnelnmate elasses: Priapulida, Ki- The unity nf al1 cephalnrhynchs is also evi- thaI Fieldia was a burrnwing sediment eater. conical scalids, irregularJy arranged in quin- The externat morpholngy and grnss anatnmy nnrhyncha and Nematnmnrpha (Malakhnv, denced by the cnmmon structural plan of the cunxes. Theanterior trunk bears twn longitudi- nervnus system which is considered the most nf Fieldia demonstrate the mnst primitive pat- nal rows nf Inng setifnrm spines directed nb- 1980). Later, newly discnvered Inriciferans, terns within the phylum. impnnant characleristic nf a phylum rank. The lIquely forward. The centra! trunk is also armed characterized by prntrusible prnboseis and 10.- Ancalagon is also. chameterized by numernus ricated abdomen, were also assigned to the central nervnus system of al1cephalorhynchs is with two longitudinal rows nf !nng lellf-like plesiomnrphie features. They are relatively large composed of a circumpharyngeal nerve ring, or . papiIJae arranged in a chevron-Iike panern. Cephalnrhyncha (Malakbnv, 1986, 1994; Adri- burrnwing wnrms (about 3-8 cm Inng) wlth a annv & al., 1989). brain, situated in the prnboseis at the base nf The taHregion is unarmed and covered with a shnrt proboscis and spacinus cylindrical and the mnuth cone, and a ventral nerve cnrd run- smooth cutiele. Based nn the gut cnntents, Lo,,- The present paper is based upnn numerous finely annulated trunk region (Walcon, 191 Ic). publicatinns cnntaining infnrmatinn nn the ning intraepithelial1y alnng the ventral side nf isella is cnnsidered a sediment eater (Conway body. The probnseis is subdivided into a well-sepa- Mnrris, 1977). rated mouth cone invaginable into the central Other Middie Cambrian headproboscid wnrms- 184 A. V. Adrianov& V. V, Malakhov: On Cepha/orhyncha .ZOOSYST. ROSSICA Val. 3 ZOOSYST. ROSSICA Vol, 3 -A, V. Adrianov& V. V. Malakiwv: On Cephalorhyncha 185
",~I'.- ~, :.~:.•":.,".: ..
Fig. I. Bodypl 1 8 Ottoia and Selkirkia - are considered to be true spherical ceotral portion armed with scaHds. priapulids. Oltoiap~()lifica has also a cylindri- There is no differimtiated neck Clrea;the pro- cal sac-like body, about 15 cm in length (Figs boscis and trunk are separated only by a slight 2-3) (Walcol1, 1911c; Conway Morris, 1977). conslriclion. The completely everted moulh The body is divided into a complelely invagi- cone is.armed with 4-5 types of spinulate and nable introvert 'and annulated trunk region. 'pec~inate priapulid teeth arranged in numerous - Fig. 2. Fossil and recent cephalorhynchs": '1: Fieldia lanceo/ata; 2, An-calagon rninor; 3,' Louisella peduncu/ata; 4, Selklrkia co/umhiai S. Ottoia prol(fica; 6, Meiopriapu/usfijiensis; 7, Ha/icryptus spinulosus; 8, larva of Tubililchus The trunk bea[s about a hundred annulations circlets eFig. 2). All these teeth are qulncun- and is slightly' curved ,to the venlral side (ha- van~atus; 9.larv1lof Plicilorlcus hadalis;)O,larva of P/iciloricus gracilisj 11, Nanoloricus mysticusj 12, PycfI(jphyes xiallyarranged in 20 oblique rows, thus each_ sp.; 13, larva of Gordius sp. 0-5, aher Conway Morris, 1977, modified; 9, afler Kristensen & Shirayama, 1988; bitual curvature). The posterior trunk is armed tooth is surrounded by four oth~rs al an equal - 10, after Hlggins & Kris~ensen, 1986; 11, a~cr Kristcnsen, 1983). with an incomplele ring of 8 lateral and dorsal distance (Conway Morris, 1977). As in Lo"i- haoks, the posteriormost portion being an sella and all modern cephalOrhynchs, the base eversible unannulated bursa tenninated by the' ofthe mouth cone is bordered by a single eirclet and well-developed dermomuscular tube are entiated anterior retractors. An intraepithelial anus. As in extani priapulids, the prohoscis is of '40-50 anteriorly-directed circumoral seal- present. T~e annulation is prominent, reflect,.. ventral nerve cord, gut mesente!ies, aqd, per- subdivided inlo an anteriorly directed invagi- ids. The scalids of the central introvert are ing Ihe arrangement of eireular muscles. The haps, a combined urogenital system are pre,- nable moult cone wilh peclinate teeth .and arrange~ quincunxially. A spaeious body cavily introvert can invaginale due 10 a selof differ- 's~nt. The teelh armature and gul structure indi- 186 A. V. Adrianov & V.V. Malakhol': On Cepha/orhyncha .ZOOSYST. ROSSICA Val. 3 WOSYST. ROSSICA Vol. 3 .A. V. Adrianov& V.V. Malakhov: On Cepha/orhyncha 187 rior trunk, eovered with unannulated cutiele, tem of spiral fibers - cutiele with compllcated 13~ bears 25-26 longitudinal rows of 6-8 papillae system of spiral fibers. used as fixatory graspers (Conway Morris, 7. Arrangement of papillae: uniform papillae 1977). There are spacious body cavity, well- irregularly arranged over the body - function- 9. _ developed dermomuscular tube and a set of ally differentiated papillae mainly concen- , anterior retraetor museIes. The museles around trated on proboseis - regularly arranged (in J4~ I the buccal tube may be interpreted as muscular rows or/and circles) and differentiated papiI- septa separating the proboscis and trunk. The lae of the mouth cone, spherical portion of ...... IJ-th ~::~::f position of the septa corresponds weil to emb- introvert and trunk . .o :o'... ,~..:.~~::.: I I ryonie septa of priapullds and larval septa of 8. Shape of papilJae: conical cuticular papillae 2.1£_0_:; _ nematomorphs. The cuspidate teeth and ab- - elongated stylet-lIke scallds _ aniculated ßHj~!mH. sence of sediments in Ihe gut suggest that Sel- scallds. Conical scalids - bifurcated or double .{ffb kirkia could be also a carnlvorous Cambrian scalids. Conlcal paplllae - smooth curved teeth. :1: priapulld worm. Conical papillae - pectinate or cuspidate teeth 6 J6 dkJ - smooth curved teeth. Conical papillae _ }~~Iilllill " 4. Primilive and advaneed stales of morpho- setifonn spines. logical characters within Cephalorhyncha 9. Musculature: continuous dennomuscular tu- " ,,"''''' ••••••• v be with circular and long"itudioal muscles _ .•.";:..:.. .:. Comprehensive comparalive-morphological continuous dennomuscular tube reduced ioto analysis of cephalorhynch morphology, con- lanice frame of separated circular and longi- .•. ..- 3_ ~~~;:~; ~:::'~::::~"" ducted on all known extinct and extant forms, tudinal bundles - circular museIes reduced. No allows us to specify the evolutionary Hnes of dorsoventral muscles - dorsoventral muscles primitive (plesiomorphic) and advanced (apo- present. No differentiated retractor muscles _ 7 @filtfim~~ morphic) states of the maln morphological eha- differentiated retraclor museIes present. No racteristics of headproboscls worms. The table protractors - protractors present. 11 whieh follows is intended to summarize the key 10. Body cavity: spacious body cavity with characters to be used in the discussion of evo- numerous coelomocytes - body cavity panly 19~ lution. reduced, with few coelomocytes. Spacious bo- .es I. Size: macrobenthie forms (cm) - meioben- dy cavity wilh numerous coelomocytes - body thic forms (mm or less). cavity replaced by supponing parenchyme. 2. Body shape: elongated sack-IIke or worm- 11. GUI: tripartite gut (fore-, mid-, and hind- ;c IIke cylindrical body - worm-lIke body com- gut) without additional subregions - tripartite pressed dorso-ventrally. Elongated saek-Hke gut with additional subregions (oesophagus, body - hair-Iike body. polythyridium, midgut diverticules). Function- 3. Introvert: proboscis and trunk weakly sep- al gut - gul reduced or degenerated (in para- ara ted, proboscis not capable of complete in- sites). verting - proboscis weil separated, capable of 12. Pharynx: non-suelting pharynx - suck- inverting completely into the trunk. Mouth co- ing pharyngeal bulbus. Armed, eversible pha- ne short, Invaginable - mouth cone relatively rynx - unanned, non-eversible pharynx. long, telescoplcally protrusible. Pig. 3. Proboscises of fossil cephalorhynchs (after Conway Monis, 1977): 1.4, Louisella peduncu/afa; slages of 13. Muscular wall of the niidgut: continuous proboscis evcrsion; 5.8. proboscis of Se/kir/da co/umbia; 9-12, Dttala profi/lea;. stages of proboscis cvcrsion; 13, 4. Neck area: neck undifferentlated - neck museular wall with circular and longitudinal lcnninal footh of Ancalogon minor; 14, scalid of Ancalagon proboscis; 15-16, teclh of Se/kir/da columhia; 17-21, dlfferentiated as a constrlction between pro- leclh of Ottoia prall/leu. muscles - continuous wall reduced into tattice boscis and trunk - neck well-differenliated, frame of separated museIes - no muscu!ar gut folded or with neck plates. Neck soft-bodied, wall. invaginable into trunk - neck non-invagina- cate that GI/oia could be a carnivorous burrow- 14. Nervous system: ventral cord non-gan- The completely everted mouth cone is termi- ble, sclerotized as apart of armour. No elosing ing cephalorhynch whose anatomy is very glionaled - ventral cord sllghtly gangllonaled, nated with multispinose or pectinate teeth of elose to that of modern priapulids. apparatus - radial or bilateral elosing appara- with some trunk ganglla. Ventral cord non- two types. The unarmed zone of the mouth cone tus present. The Cambrian tubicolous Selkirkia is a worm- gangllonated - ventral cord metamerously is followed by about 5 circlets of thln anteriorly 5. Trunk: trunk worm-lIke;no! differentiated like soft-bodied burrowing cephalorhynch gangllonated. Circumpharyngeal brain weakly directed circumoral spines, arranged quin- into subregions - trunk elearly differentiated (0.3-7.5 cm), also considered a true priapulid ganglionated - brain distinctly ganglionated. cunxially (Fig. 3). The other two portions of into subregions. (Wa!con, 1911c; Conway Morris, 1977). The 15. Excretory system: protonephridia with proboscis are anned with numerous minute 6. Integument: simple elastie cutiele - eutiele smooth. trunk was surrounded with a finely numerous (hundreds) solenocytes - protone- spines and posteriorly dlreeted scalids, all selerolized inlo loricated armour. Cutiele elas- annulated parchment-Iike nonchitinous tube, phridla with few cyrthocytes. Monociliary ter- quineunxially disposed. As in reeent priapullds, t1c, smooth or finely annulated - metamer- open at both ends and oval in cross-section. minal cells - bicillary terminal cells. scallds diminish to the posteriorend. Theante- ously selerotized armour. Cutiele without sys- 16. Fertilization: external fertilization - in- 188 A. V. Adrianov& V. V. Malalchol1:0n Cephalorhyncha :ZOOSYST. ROSSICA Val. 3 ZOOSYST. ROSStCA Vol. 3 °A. V. Adrianov& V. V. Ma/aJclwv: On Ceplw/orhynclw ternal fertilization by means of spermatophore ward while proboscis everted; longitudinal wall 189 transfer - internal fertilization by means of muscles contracted and dragged the body for- /hioseopa (3-7 mm) was a soft-bodied cylin- muscular layer on the gut surface is also re- true copulation. ward while trunk papillae relaxed. The Ur- drical worm, characterizeq by a well separated dueed, being replaced by lattice-like muscular 17. Copulatory organs: no copulatory organs Cephalnrhyncha were sediment and detritus spherical introvert with a long eylindrical piexus. In contrast to primitive headpTohoscis - eopulatory spines present - true penis de- eaters. mouth cone (Waleott, 1931). Analogously to wanns, kinorhynchs have specialized retrac- veloped. The Middle Cambrian Fielt/ia and Allealagon modern interstitial wonns, the anterior intro- tors and protraclors. Small body size resulled 18. Egg production: high egg production appear to be very elose tn the prototype men- ven was armed only with 1-3 cirelets of long in Ihe development of internal fenilization and (thousands of eggs) - low egg production tioned above in having most primitive charac- modified scalids. modified sperm. Phylogenetical conelusions (few eggs). High egg production (thousands of ters. Being a sediment eater, Fielt/ia is charac- The evolulionary trend menlioned above has concerning the evolutionary patterns within eggs) ~ extremely high egg production (mil- terized by a non-invaginable proboscis and led to the interstitial metamerous cephalo- Kinorhyncha 3re mainly based on the external lions of eggs). uniform conical papillae scattered over thc rhynchs - ancestors of recent kinorhynchs trunk morphology and constructions of the 19. Sperm structurc: "primitive" sperm - mo- wh oIe body. The ooly inversible portion is the (Adrianov & Malakhov, (994). The size of neck elosing apparatus (Adrianov & Mala- dified spenn with aberrant patterns. mouth cone. The carnivorous Ancalagon is adult kinorhynchs ranges from aboutO.3 mm to khov, 1994). 20. Mode of life: marine burrowing worms - characterized by differentiated ,papillae, the nearly 1-1.2 mm in length. Due to abrasion, The major evolutionary stock of cephaJo- marine interstitial fomls. Free-living mobile anterionnast of them being smooth curved penetratiQn into interstitial biotopes resulted in rhynchs leads to macrobenthic priapulids. As worms - semi-sessile fubicolous wonns. Free- teerh. As in reeent Halicryptus, the trunk of formation of selerolized armour 10 prolecl Ihe nOled above, the true priapulids appeared in Ihe living fonns - temparary ectoparasites - en- Ancalag01l was eovered with numerous seta- miniaturized body of kinorhynch. Being com- Middle Cambrian. In contrast to kinorhynchs, doparasites. Parasites of marine hasts - para- like spines. As noted (Ibove, both Cambrian posed of separate rigid plates, Ihe metamerous priapulids have retained numerous primitive sites of freshwarer and terrestrial hosts. forms possessed a spacious body cavity, der- armour provides bath effective protection and features common for aH fossil forms: invagi- 21. Feeding meehanism: sediment and detritus momuscular tube, but no retructors. re"sonable flexibility of the trunk to-allow for nable (not protrusible) mouth cone; elastic t:<:lters- carnivorous forms. Sediment and de- Further evolution of cephalorhynchs resulted specific locomotion. The external segmenta- covers; continuous dermomuscular tube and tritus e,Uers - sestonophagous forms. Sedi- in the formation of functionally differentiated Iion is reflected internally in the muscIe ar- muscular gul wall; spacious body cavity (Fig. ment and detritus eaters - baeteriovorous and papllIae gathered on the proboscis, capable of rangement, glands. sensory structures and 4). Due 10 their bodyplan and anatomy, similar herbivorous collectors - predators with suek- being compJetely withdrawn and thus consi- nervous system. 10 these of Ur-Cephalorhyncha and primitive ing feeding apparatus - "temporaryectopara- dered a true introvert. This introvert prornotes The body of kinorhynchs is also subdivided fossil headproboscis worms, priapulids would sites with sucking feeding apparatus - endo- a more effective burrowing locomotion. Com- into two main regions: the compIetely inversi- seem to be most pJesiomorphic taxon of extant parasites with degenerated gut and absorptive plete invagination of the introvert should be ble head and the trunk metamerously segmen- cephalorhynehs. In contrast to primitive sedi- feeding mechanism. carried out by specialized muscIes - retractors, ted into I1 zonites (Fig. 4). The spherical head ment eaters, the evolution of an invagin(lble is connected with the trunk by short inversiblc originated apparently from "normal" longi- mouth cone and eversible anterior pharynx of 5. Phylogeny within eephalorhynehs neck wh ich could be considered a posterior tudinal museies of body wall. The invaginable macrobenthic priapuIids. charaeterized mainly ponion of the introven. When the introven is mouth cone and ceotral introvert became elon- by a carnivorous mode of life , resulted in The ancestors of cephalorhynchs (Ur-Ce- withdrawn, the neck plales form a radial or gated and equipped with more or less regularly development of pectinate (muItispinose) or phalorhyncha) were apparently relatively bilateral e10sing apparatus. Though the head arranged (in oblique rows or eirelets) pupilJae: cuspidate teeth. These teeth are considered an large (cm) burrowing soft-bodied worms wirh oral spines, eircumora! and "normal" scalids: region and neck are not serial homologists of important synapomorphous characteristic uni- a eylindrical trunk covered by elastic integu- trunk zonites, they are traditionally considered The cvolutionary stage mentioned above ap- fying all known extinet and extant priapulids. ment (Fig. 1). The elastic cuticle could bear as the first and second segments, Ihus the total pears to correspond weil to the Middle Cam- One of the evolutionary tendencies within Ilumerous uniform conical papillae irregularIy of 13 body segments might be aeeounled (Ze- brian Louisella. Because of pcculiar mixture of Cambrian Priapulida is their transfer to tubi- arranged. With thc exception of the anterior- linka, 1928). primitive and special advanced features, 1...ou.- colous, or semi-sessile mode of 'ife. The trunk most ponion (mouth cone), the weakly sepa- A remarkable advanced charaeter of kino- isella should be considered an early separated of Selkirkia was located within a Ihin, parch- rated pro-proboscis was not invaginable into rhynchs is the retraclile moulh cone normally lateral stock of Cephalorhyncha. In contrast to menl-like tube. Nevenheless, Selkirkia was the trunk. Ur-Cephalorhyncha possessed a armed wilh 9 (the 10lh reduced) exlernal and Fieldia and Ancalagoll, Lollisella is charac- stilla free-living, mobile, probably carnivorous continuous dermomuscular tube and spacious 20 internal styles arranged pentamerously. terized by an elongated mouth cone with regu- burrower. The finely annulated tube was body caviry, fiJled with fluid. There were no These styles are considered 10be serial homol- larly (quincunxial!y) arranged spines followed secreted entirely by the worm and, according specialized retractors. As in the known cepha- ogists of proboscial scalids. Three types of by separated eircIet of modified circumoraJsca- to Stormer (I 944), could be compared wirh lorhynchs, the mode of burrowing was hydrau- scalids are dislinguished: circumoral, spino- lids. However, other scalids still remain to be lorica of modern larval priapulids. Within the lie (Zenkevich, 1944; Hammond, i970; Con- and trichoscalids. There are always 10 eir- irregularly arranged. The slightly compressed modern Priapulida, this tendency to a semi-ses- way Morris, 1977; Osipova, 1982). The cyele cumoral scalids. Anlerior scalids are quincun- trunk bears bilateral rows of specialized papillae, sile mode of life is realized in Maceabeus, the of locomotion of the ancestral cephalorhynch xially arranged in multiples of five, thus giving thus produeing distinct bilateral symmetry. only sestonophagous cephalorhyneh. In con- cDuld be described as folIows: circular body- pentaradial symmetry. Because of a selective One of the main evolutionary tendencies trasl to Selkirkia, the tube of Maecabeus is wall museIes contracted thus increasing the bacteriovorous aod herbivorous diet, the 000- within eXlinct and extant cephalorhynchs is formed /rom aggIutinated plant fragments (Por pressure of the cavity fluid and elongating the eversible and unarmed sucking pharynx was & Bromley, 1974). miniaturization of the body which has enabled body from thc anterior end; the proboscis start- developed. Anolher advanced feature relating them to occupy a new niche - interstitial bio- The best known Cambrian priapulid is Ol/oia, ed to even, while trunk papillae acted as an- to the selerotized armour is reduclion of Ihe topes. The first meiobenthic forms are also characterized by same evolved charaeters, as chor; proboscial papillae gripped sediment and continuous dermomuscular tube. Circular found wirhin Middle Cambrian worms. Being compared with olber fossil worms: several typ- prevented the body from being pushed back- museIes are reduced and funetionally convened similar to recent meiobenthic priapulids, Leey- es of pectinate teeth; anteriorly-directed cir- inlo diagonal and dorsoventral museIes. Asolid eumoral scalids (pattern common for all extant 8 ;.. ",. ~.~ ...~ '"" ~ ~ ~ oll" ~ ~ •• ~ ~ £ C;; ~ '" on£ ?i > ~ ~i mc ~.'" ~ < !2- ~ '",. ~ ~ ~. ... '"" ~ t ~ {J" 0-~ > ~~. 7 Fig. 4. Morphology of extant cephalorhynchs: ], Priapulus caudatus; 2, Tubiluchus areticus; 3, Maccabeus tentaculatus (1-3 with invagin- ated mouth cone); 4, larva of Halicryptus spi- nulosus, with completely invaginated intro- 5 vert; S, Nanoloricus mystLeus (after Kristen- sen, '1991a); 6, Pycnophyes sp.j 7, larva of Gordius sp. (5-6 with completely"everted in- troyert). 192 A. V. Adrianov & V. V. Malakhov: On Cephalorhyncha -ZOOSYST. ROSSICA Val. 3 ZOOSYST. ROSSICA Val. 3 -A. V. Adrianov& V. V. Malakhov: On Cephalorhyncha cephalorhynchs); regular quincunxial arran- We would Iike also to draw attention to some 193 gement of scalids; clear neck constriction; pro- evolutionary trends realized within modern Early stages show quincunxial pattern in scalid les; complicated set of retraetor and protractor minent annulation of trunk subdivided into de- Priapulida. In addition to macrobenthic pri- arrangement, while latter stages of Priapulus muscles. Nevertheless, some of these similari- finite subregions; invaginable anal bursa; pre- apulids (Priapuliles-Priapulus-Ac:atllhopri- are characterized by longitudinal seMes of scal- ties have been formed on thecommon ancestral Clnalfixatory hooks; differentiated retractor and apu/us - Priapulopsis - Halicryplus), which ids on the proboseIs. Ali larvae have an invagi- morphological basis (priapulid-like prototype). protractor muscles. share more or less primitive characters, the nable neck area, which folio ws the proboseIs In contrast to that, etose similarities between The discovery of a Carboniferous priapulid, microscopic Tubiluchus and Meiopriapillus during invagination into lorica. The neck plates loriciferans and loricated rotiferans or tardi- Priapillites (Schram, 1973), allows to assurne appeared to occupy meiobenthic marine bio- can aet as a elosing apparatus. The neck area grades, also anned with sueking "boring ap- Ihat the evolutionary radiation of main pri- tapes. 80th priapulids evolved as selcctive 01 dwarf priapulids anned with cuticular plates paratus", are the only remarkable examples of apulid stocks, wh ich evolved to modern forms, detritovorous, bacteriovorous and herbivorous~ is named "thorax". Because of smaJl size, the convergence aiming to meet similar functiomd could be between the Cambrian and Carbon. feeders, being characterized by some advanced dermomuscular tobe is reduced into a lattice requirernents. The Upper Carboniferous Priapillites kmzec- features. Both worms have highly modified frame of separated circular aod longitudinal Most loriciferans are also characterized by I/ivorum shows rcmarkable similarities with pectinate teeth, diffcrentiated scalids and addi- museIes. As in kioorhynchs, the body cavity is tripartite retractile mouth cone equipped with modern Priapll!us callt/alus, thus giving an tional gut filters - polythyridium, unknown in also reduced. Most larvae are detritoyorous and externat and internal armature of various sty- exccllent example of the "slow evolution". The other eephalorhynchs. So far 6 species of Tu- bacteriovorous. J udging lrom the teeth struc- let-likestructures (Kristensen, 1991a, 199Ib). simiJarities include: shape ofbody; monoeaudal biluchus have been deseribed, and this genus ture, Halicryptus larvae could be carnivorous. The evolution of this organ is connected with tail region; number of trunk annuli; arrange- demonstrates the largest diversity within Solt-bodied larvae 01 MeiopriapuJus and their earnivorous or ectoparasitic mode of Iife wh ich meot rmd shape of proboscial scalids; propor- known Priapulida. At the same time, Tubilu- direct development are considered as second- also resulted in formation of the sueking trip'-lr- tiolls of introvcrt to trunk (Conway Morris, chus appears to retain some primitive features, ary features (Higgins & Storch, (991). Loricated tite pharynx and "boring apparatus". It is in- 1977). Based on these similarities, Priapu/us which inc!ude the elearly recognizable quin- larvae are unknown for Cambrian priapulids. teresting to note that primitive Higgins-Iarvac may be considcred the most primitive of the cunxial pattern of scalid arrangement (not Because of elose sirnilarities to larvae of dwarf have unarmed non-tetescopic mouth cones extant macrobenthic Priapulida. longitudinal se ries as in most other priapulids) priapulids, interstitialloriciferans are supposed to wh ich seerns to be still an eversible structure Nevertheless, it should be noted that many of and the eversible pharynx. Meiopriapulus and be neotenic taxon of eephalorhyoehs, originatiog (Kristensen, (983). Cambrian stocks (including true priapulids Sel- Maccabells appear to be thc most advanced lrom Priapulida (loffe & Kotikova, 1988; Adri- The spherical portion of the introvert is armed k;rkia, OUoia, Lecylhioscopa, protoccphalo- priapulids. The former genus is the only pri- anov & al., 1989). This assumption is weil evi- with numerous scalids (up to 235) arranged in rhynchs Fieldia and Ancalogoll and repre- apulid with a non-eversible and unarmed pha- denced by their anatomy and ultmstrueture (see up to nine circlets (Higgins & Kristensen, sentntive of a separate taxon Louisella) ap- rynx, while introverts of hoth priapuJids are below) (Fig. 4: 5). The striking resemblane~ 01 1986). The lorielferan introven exhibits all parclltly became extinct and have Ieft no rec- equipped with highly modified and specialized Pliciloricus gracilis larvae and larval Tubilu- types of scalids previously known' within Ce- ognizable dircct descendants within modern scalids similarto those of Jorieiferans and kino- ehu" is espeelally notewonhy. So, il only pli- phalorhyncha: elrcumpharyogeal scalids (cla- farms. There is !ittle place for doubts that the rhynchs. MoC('abeus is the only known ses- ciloricid tarvae were found, there is no doubt voscalids); aniculated or highly modilied spi- similarities betwecn extinct and extant worms tonophagous semi-sessile priapulid. that they would be designated as larval stages noscalids; tooth-Iike struetures; doubled scal- (Allcu!ugon- Halicryplus; DI/oia - Halicryp- Recent priapulids (with the exception 01 Mei- 01 still unknown speeles of TuhUueh/ls. At the ids; and trichoscalids. tus; Lecythioscopa - Meiopriapulus) have opriapulus) have specialized interstitiallarvae. same time, adult loriciferans, especially Na- In contrast to priapulids, loriciferan larvae arisen by parallel evolution to meet similar Loricated non-metamerous armour (lork,,) noloricidae, exhibit a number of apomorphie have a non-retractable thorax armed with cutic- lunctional demands (mode 01 Hfe or feediog composed of longitudinal plates is a synapo- charaeters, more similar to those of kino-' ular plates, which has become a ponion 01 Ihe mechanism). For example, the protrusible (or morphic character 01ali priapulid larvae. There rhynchs. So, if ooly adulr Nanolorieldae were trunk annour. Comparing the larvae with the telescopie) mouth cone of kinorhynchs, lori- is no doubt, that theancestralloricu of priapulid lound and priapulid-Iike larvae were still un- adults, it may appear that the larval thorax is ciferans and gordiids could be attributed to larvae initially was round in cross section, being known, there eould hardly be any doubt that only homologous with the area posterior to independent evolution ofthe anteriormost pro- composed of about 20 thin longitudinal plates Loricilera would be regarded as a group eloser trichoscalids (Higgins & Kristensen, 1986). bosels to meet simHar demands connected with delimited by 20 equaliy spaced ridges. Both to Kinorhyncha than to Priapulida. The area of trichoscalids in adults is hOrllO- leeding mechanism (see below). At the same plates and ridges originate from paraliel cutic- The commoo features of lorieiferans and lar- logous with the larval collar (closing appara- lime the major residual similarities (bodyplan; ular lolds of the solt-bodied abdomen 01 anees- val priapulids Inelude: regular arrangement of tus), wh ich corresponds weil with neck c10sing invaginable proboseIs and trunk; sensory-Io- tral juvenile fonns. This type 01 the lorica is scalids; neck region subdiYided into true neck apparatus of kinorhynchs. Therefore, lorici- cornotory proboscial papillae; plan of nervous louod in the initial (first) larval stl'ge 01 Pri- and thorax anned with cutieular plates; non- feran thorax should be considered homologous system, etc.) undoubtedly evidence shared in- apu/us. The primitive type 01 weakly selero- metamerous loricated armaur; rnuscular lattice with the anterior portion of the kinorhynch frameof eircularand longitudinal buodles; differ- o heritance from a common ancestor (Ur-Cepha- tized lorica remains in all stages of interstitial trunk, where the first zonite (or zonites) differs lorhyncha). Tuhiluehus. The teodency to flattening is as- emiated retraetors and protractors; structure of from successive ones (Fig. 2). No doubt, that In muddy marine sediments, the carnivorous sociated with miniaturization of the stages pe- body cavity; combioed urogeoital system. the larval thorax of toriciferan is' homologous Aflcalagofl, which became extinct, was ap- netrating into interstitial biotope. The f1attened Many 01 the apomorphie eharaeters common with that of larval tubiluchid and wrinkled neck parently replaced by Halicryptus, also con- and sclerotized armour appears to be more -er- for loriciferans, kinorhynehs and gordiid lar- orthoracicarea of otherpriapalid larvae (Fig. 2). sidered to be obligate predator. Extinct car- fective in protecting the trunk of miniaturized vae have arisen by parallel evolution aimed at Nematomorpha are eonsidered the most ad- nivorous true priapulids were replaced by mod- fonns. As with adults, ali larvae are cha"lc- resolving the identical mechanical problems. vaneed cephalorhyneh taxon. They are as- ern macrobenthie priapulids. In meiobenthic terized by an invaginable mouth cone, pectinate These eharaeters are: protrusible mouth eone; soeiated with the endoparasitic mode of Iile that biotopes, Leeylhioseopa was replaced by dwarf or cuspidate teeth (up to 15 types in Priapu- the annour composed of thorax and lorica; the results in specific external morphology and priapulids. lus), and single circlet of circumoral scalids. neck elosing apparatus; reduction of circular anatomical features (May, 1919; Eakin & Bran- museIes into diagonal and dorsoventral bund- denburger, 1974; Bresciaoi, (991). A long his- 194 A. V. Mr/anov& V. V. Malakhov: On CephiJ/orhyncho 'WOSYST. ROSSICAVol. 3 ZOOSYST.ROSSICAVol.3 -A. V. Adr/anov& V. V. Malakhov: On Cephalorhyncho 195 "cephalorhynchous" features: eylindrica! Order ANCALAGONIDA ordo n. worm-like body divided into proboscis and soft Farn. Ancalagonidae Conway Morris, 1977 .annulated trunk eovered with softeutiele; intro- vert armed with regularly arranged scalids; • Ancalagon Conway Moms, i977 septal complex, ete. Uke loriciferans, gordiid larvaehave the retractile telescopic mouth eone SubphylumI!UCI!PIlALORHYNCHAsbph. n. armed with 24 minute teeth and :i intemal sty- C1ässLOUISELLIDAcl. n. lets forming the effective "boring apparatus" (Fig. 4). The introvert aclS as a penetrating Order LOUlSELLIDAordo n. organ and is also used in speeific ncephalo- : rhynchous" locomotion. Apparently, active Farn. Miscoiidae W~lcott, 1911 penetration through host covers recapitulates • !--ouisella Walcott, ,1911 (Miscoia Walcott. 1911) carnivorous or ectoparasitic mode of life of gordiid aneestors. Nematoniorphs eould be de- Class PRIAPULIDA Delage & Herouard, 1897 scendents of ancestral meiobenthic carnivorous cephalorhynehs, whieh bored the skin of their Order SELKIRKJOMORPHA ordo n. victims aod sucked out the content. We may Farn. Setkirkiidae Conway Morris, 1977 suggest the evolutionary transition from eeto- parasilism to endoparasilism. As in free-living .SelkirkiaWalc~tt, 1911 interstitial cephalorhynchs, the tendeney to mi- niaturization results in a reduetlon of the body Order OTTOIOMORPHAordo n. cavity and eircular museIes. In contraS! to other 'cephalorhynehs, dwarf nematomorph larvae Fam. Ottolidae Wakott, 1911 have well-developed protractor muscles (Zapo- .OttoiaWaico11,1911 tosky, 1974, 1975). '\ The scheme of phylogenetic relationships Order PRtAPULOMORPHA Salvini-PI~wen. 1974 Fig. 5; Phylogenetic rel Order Se1kirkiomorpha ordo n. short, conical; 00 visible neck; cuspidate teeth metamerous cuticular armour, composed of 11 Subelass Neclonemaloidea Rauther, 1930 of several types, central spine of anterior teeth zonites; zonites composed of entire cuticular Priapulida; macrobenthic worms; pectinate strongly enlarged and curved; proboscial scal- rings or subdivided into tergite and stemites; Nematomorpha; reduced proboseis and trunk tee1h of two types; no neck; proboscial scalids ids triangular, of three types; trunk finely an- foregut composed of buccal tube armed with in adults separaled by septum; cutiele smooth, uniform, arranged in regular rows; aotenor nulated, not differentiated into subregions; no stylets and non-eversible sucking pharynx; without areoles; trunk hearing two double rows trunk bearing papillae arranged in several circ- tail; trunk spines hair-like, irregularly arrang- musculature and nervous system metamerous; of natatory bristles; body cavity spaeious; gut lets; proboseis and trunk subdivided by museu- ed; externat fertilization. Carnivorous. Single circular muscles reduced; dorsoventral muscles reduced and degenerated in middle trunk; ma- laT septa. Tubicolous; presumably carnivorous family Halicryptidae Salvini-Plawen, 1974. always present; terminal prolonephridial cells les with single testis; female ovary not de- and detritovorous. Single family Selkirkiidae biciliary; direct development; intemal fertiliza- limited, eggs filling body cavity; reproductive Conway Morris, 1977. Order Setleoronaria Salvini-Plawen, 1974 tion with spermatophore. Detritovoroljs, bacte- system opening terminally; larvae with worm- riovorous, herbivorous. Two orders: Cyelo- like trunk; no extemally differentiated neck rhagida and Homalorhagida. Order Onoiomorpha n. ordo Priapulida; small worms; anterior circlets of area; mouth cone underdeveloped (cuticular long proboseial scalids forming a crown of invagination with two hooks); proboscis with Order Cyclorhagida (Zelinka, 1896) Priapulida; macrobenthic warms; pectioate elongated tentaeles; other scalids of several two eirelets of spiny scalids. Parasites of marine teeth of 4-5 types; neck area represented as Higgins; 1964 types; pharynx armed with pectinate teeth; crustaceans. One order Nectonematida Hyman, constriction between proboscis and trunk; pre- neck area indistinctly separated from trunk; 1951 with diagnosis identical to \hat of the elass. anal subregion of trunk bordered by eirelet of preanaltrunk subregion bordered by cirelet of Kinorhyncha; trunk oval or cyllndrica1 in cross 8 cuticular hooks; trunk cuticle annulated. Pre- hooks; tail absent. Tubicolous, semi-sessile; section, compressed ventrally or laterally; neck sumably carnivorous and detritovorous. Single closing apparatus of uradial" type; trunk wnit- sestonophagous. Single family Chaetostepha- Subclass Gordioidea Rauther, 1930 family Ottoiidae Walcon, 1911. nidae Salvini-Plawen, 1974. es with laleral, dorsal and terminal spines; pha- ryngeallumen rounded or multiangular in cross Nematomorpha; rudimentary gut opening in Order Priapulomorpha Salvini-Plawen, 1974 seclion; diagonal museles present. Four sub- Class Lorieifera Kristensen, 1983 subterminal eloaca; body cavity replaced by orders: Protorhagae Adrianov & Malakhov, supportive parenchyma; paired gonads run- Priapulida; macrobenthic and meiobenthic 1994; Cryptorhagae Higgins, 1968; Concho- Eucephalorhyncha; meiobenthic forms; body ning lengthwise in the body in both sexes; warms; pectinate Of cuspidate teeth of several rhagae Zellnka, 1907; Cyclorhagae (Zelinka, of larvae and adults divided into weil differen- larvae with weil separated proboscis and trunk types (up to 15); proboscial scalids of several (896) Zelinka, 1928. tiated introvert and trunk, covered with lorka; separated by septa; trunk annulated; mouth co- types, arranged in longitudinal rows and circ- neck always weil differentiated, armed with ne telescopically protrusible, armed with termi- lets; neck area preseot Of abseut; trunk annu- cuticular plates, anterior part of larval neck may Order Homalorhagida (Zelinka, 1896) nal teeth and stylets; proboscial scalids ar- lated, tail subregion always present; trunk and form closing apparatus; mouth cone telescopi- Chitwood 1958 ranged in Ihree eirelets; larval retractors and tail papillae differentiated, usually of several cally retractile, usually armed with external and types; development with interstitial larvae; intemal stylets; proboseial scalids weil differ- Kinorhyncha; trunk triangular in cross sec- protractors always present. Parasites of insects. larvae with weil separated invaginable neck entiated and including clavo-, spino-, tricho- lion, compressed ventrally; neck elosing ap- Four orders: Gordiida, Paragordiida, Chor- area and non-metamerous lOlita; external and scalids, and tooth-like spines; foregut com- paratus of "bilateral" type; terminal spines pre- dodida, Parachordodida. internal fertilization. Carnivorous and detri- posed of buccai tube, armed with stylets, and sent or absent; pharyngeal lumen triangular; tovorous. Two families: Priapulidae Gosse, sucking pharynx; dermomuscular tube reduced diagonal museIes absent. Single suborder Ho- Order Gordiida Hyman, 1951 1855 and Tubiluchidae van der Land, 1970. into set of separated eircular and longitudinal malorhagae Zelinka, 1896 with two families: bundles; diagonal and dorso-ventral museIes Pycnophyidae Zelinka, 1907 and Neocentro- Gordioidea; posterior end of male body bifur- Order Meiopriapulomorpha ordo n. present; excretory and reproductive systems phyidae Higgins, 1969. cated, caudallobes move'd apan; males charac- combined into urogenital organs; internat terized by crescentic cuticular fold behind eloa- Priapulida; smaH meiobenthic wonns; mouth fenilization; protonephridial cells monociliary. Clas. Nematomorpha (Vejdovsky, 1886) cal aperture; females with rounded posterior cone with unifonn multispinose teeth; pharynx Carnivorous or bacteriovorous, presumably Hyman, 1951 end; dark neck ring present; cutieleusually unarmed, non-eversible; neck area marked by temporary ectoparasites. One order Loricifera without or with sparse areoles; cloacal opening papillae; preanal trunk subregion borde red by Kristensen, 1983 with diagnosis identical to Eucephalorhyncha; adult worms large, with in centre of cloacal disc; larvae with pointed cirelet of numerous hooks; pharynx followed that of the elass. Two families: Nanoloricidae hair-Iike body; body of adults extemally not posterior end. Distribution worldwide. Single by filtering organ - polythyridium; no tall sub- Kristensen, 1983 and Pliciloricidae Higgins & divided into proboscis and trunk; proboseial family Gordiidae May, 1919. region; larvae without lorica; viviparous with Kristensen, 1986, region bordered only by cuticu1ar ring or inter- direct developmenl. Detritovorous. One family nal septa; larvae with more or less separated Order Paragordiida Kirjanova, 1954 Meiopriapulidae fam. n. with the diagnosis Class Klnorhyncha (Reinhard, 1881) introvert, intemally separated by septa; cutiele identical to that of the order. Apparently, this Pearse, 1936 in adults with system of spiral fibres; no cireular order could inelude the poorly studied Cam- museles; gut reduced; no retractors in adults; no Gordioidea; body cylindrical; posterior end br/an • Lecythioscopa Walcon, 1911. Eucephalorhyncha; meiobenthic forms; body excretory system; reproduclive system hyper- of males deeply bifurcated, unarmed or with more or less compressed ventraUy; conical mouth trophied; internal fertUization with true copu- two rows of short spines; posterior end of fe- Order Halicryptomorpha ordo n. cone retractile, with ext~rnal and internal sty- lation; undulatory locomotion (swimming) in males trilobed, unarmed; anterior end with lets; central portion of introvert with spino- and adults. Parasites of marine, fresh-water and three head protrusions; wide dark neck ring Priapulida; macrobenthic wonns with meio- trichoscalids; neck area sclerotized ioto radial terrestrial arthropods. Two subclasses: Nec- present; areoIes smalI. Distribution worldwide. benthic larvae; in adults introvert relatively or bilateral elosing apparatus; trunk bearing tonematoidea and Gordioidea. Single family Paragordiidae Heinze, 1935. 200 A. V. Adrianov& V.V. Malakhov: On Cephalorhyncha .ZOOSYST. ROSSICA Val. 3 ZOOSYST. ROSSICA Vol. 3 .A. V. Adrianov& V. V. MaJakhov: On CephaJorhyncha 201 Order Chordodida Kirjanova, 1954 Adrianov.A.V .• Malakhov. V.V." Yushin, V.V.1990a. 375. london, Ncw York: WUey-üss Ine. Systematik der Priapulidae: Chaetostephanus pra- Fine structure of the cu tide of Pycnophyes kielensi.<; Krislensen, R.M. 1991 b. loricifera - a general biologi- eposteriens, der Vertreter einer neuen Ordnung Se- Gordioidea; anterior and posterior body ends (Kinorhyncha, Homalorhagida). Zool. Zhurn., 69 cai and phylogcnetic overview. Z00logical systematp ticoronaria. Zeitsehr. zooL Syst. Evo/utions/orsch.. (l): 5-11. (In Russian). markedly tape ring. the laner rounded in bolh ics Symposium: New higher taxa presented by their 12: 31-54. Adrianov, A.V., Chesunov A.V. &. Spiridonov. S.E. discoverers. Verh. dtsch. zooL Ges., 84: 231-246. Schepolieff, A. 1907. Die Echinoderiden. Zeitsehr. sexes; cuticle with areoles; longitudinal mid. 1990. Post-embryonic developmenl of Pycnophyes Kristensen, R.M." Higgins, R.P. 1991. Kinorhyncha. wlss. ZooL • 88: 291-326. ventral groove running aloflg entire body. Par- kie/ensi.<; (Kinorhyncha, Homalorhagida). ZooL In: E. Harrison (ed.). Microscopic analomy 0/ in- Schram, F.R. 1973. Pseudocoelomates and a nemcr. asites of tropical inseclS. Single family Chor- Zhurn., 69(6): 132-137. (In Russian). vertebrates, 4: 377-404. London, New York: WHey- tine from thc IIIinois pennsylvanian. J. Paleont., 47: dodidae May. 1919. Andrassy, I.A. 1976. ElIOlution as a basis jor the sys- üss Inc. 985-989. tematization 0/ nematodes. 228 p. Budapest: Aka- Kristensen. R.M. &: Shirayama,Y. 1988. PliciJoricus Skryabin. K.I." Schulz, R.S. 1931. Gelmintozychelo- dcmiai Kiado. hadalis (Pliciloricidae), a new loriciferan species Order Parachordodida Kirjanova. 1954 veka IHelminthoses of man I. In: Osnovy meditsin- BekJemishev, V.N. 1964. Osnovysra"vnitelnoyanatomü colleetcd trom the Izu-Ogasawara trench, Western skoy gelmintologii IFundamentals of medical bespozvonochnykh IPrinciples of comparative ana- Pacific. ZooL Science, 5: 875-881. helminthology I. 178 p. Moscow: Gosmcdizdat. Gordioidea; posterior end of males lobulated lomy of invcrtebrales I. Vol.l. 432 p. Moscow: Nauka. Land. J. van der. 1968. A new Aschelminth, probably Storch, V.• Higgins, R.P. " Morse, P. 1989.lnlernal into two short lobes always armed; posterior Bresciani, J. 1991. Nematomorpha. In: E. Harrison related to the Priapulida. Zoo! Meded. Leiden, 42: anatomy of Meiopriapulus jijiensis (Priapulida). (cd.). Microscopic anatomy 0/ invertehrates, 4: 197- end of}emales rounded; irregularly rounded 237-250. Trans. amer. micr. Soc., 108: 245-261. 218. London, New York: Wiley-Uss Ine. Land, J. van der. 1970. Priapulida. ZooL VerhandL, Siorch, V., Higgins. R.P." Rumohr, H. 1990. Ultra- cloaeal dise and cloacal opening moved ven- Brien, P. 1961. Elements de zoologie. Notions cl'anato- 112: 1-118. slructure of introvcrt and pharynx of HaLicryptus trally; dark neek ring present; areoies variing; mie comparee. 2. Les Coelomutes Hyponeriens. 715 Land, J. van der. 1982. A new species of Tubiluchus spinu/osus (Priapulida). J. MorphoL, 206: 163-171. larval Irunk relatively short and Ihick wirh blunt p. üege. (Priapulida) from the Red Sea. NetherL J. Zoo/., 32: Siorch, V.• Higgins, R.P., Malakhov, V.V. &. Adrianov. posterior end. Parasites of beetles in mountain Chitwoo~, B. &. Chitwood, M. 1950. fntroduction to 324-335. A. V. 1994. Mlcroscopic anatomy and ultrastruclurc springs. Single family Parachordodidae Heinze, nematology. 213 p. Baltimorc (Md): Monum. Print. Land, J. van der. 1985. A new species of TuhiLuchus of the introvert of Priapulus caudatus and P. tuber- Co. 1935. (Priapulida) from the Pacific Ocean. Proc. ned. Akad. cu!atospinosus (Priapulida). J. MorphoL., 220: 281- Conway Morris. S. 1977. Fossil priapulid wonns. Spec. Wet. (C). 88: 371-377. , 293. Pap. Pa/eonto/.. 20: 1-101. Lang, K. 1953. Die Entwicklung des Eies von Priapulus Stormer, L. 1944. On thc relationships and phylogcny Eakin, R.M. &. Brandenburger. J.L. 1974. Ultrastruc- caudatus Lam. und die systematische Stellung der of fossil and recent Arachnomorpha, a comparaliyc Acknowledgemenls tural features of a Gordian worm (Nematomorpha). Priapuliden. Arklv Zoo/ (2).4: 321-348. study of Arachnida, Xiphosura, Eurypterida, Trilo- J, UlJrastr. Res., 46: 351-374, . Malakhov, V.V. 1980. Cephalorhyncha - a new phylum bita and other fossil Arthropoda. Skr. norske Vi- Th~ prc:)cnt publication was supporlcd by Russian Grasse. O. Poisson. R. &. Tuzet, O. 1961. Zoologie. J. of thc animal kingdom uniting Priapulida, Kino- densk. Akad., S: 1-1S8. Foundation of Fundamental Rcscarchcs, projeclS No. 93- Invertebres. 9I9 p. Paris. rhyncha, and Gordiacea, and a system of Aschel- WalcolI, C. 1911a. Middle Cambrian annelids. Cam- 04-6798 und No. 94..()4-13620a. Grobben, K. 1908. Die systematische Einteilung des minthes wonns. ZooL Zhurn., 59(4): 485-499. (In brian geology and paleontology. 11.Smithson. mise. Tierreiches. Verh. zool. -bot. Ges. Wien, 58 (10): 491- RussianL Col/ns .• 57: 109-144. 51 I. Malakhov, V.V. 1986. Nemmody: stroenie, razvitie, WalcOtl, C. 1911b. MiddleCambrian holothurians and References Hammarsten, O. 19.13. Beiträge zur Entwicklung von sisJema i/iLogeniya lNematodes: structure, develop- medusac. Cambrian geology and paleontology. 11. HaJicryptus spinu!osus Sieb. ZooL Anz., 41: 501- ment, c1assification, and phylogeny I. 215 p. Mos- Smithson. mise. CoLlns. ,57: 41-68. 505. cow: Nauka. (In Russian). Adrianov, A.V. & Malakhov, V.V.1990. Sense organs Walcott, C. 1911c. Middle Cambrian annelids. Cam- Hammarsten, O. 1915. Zur' Entwicklungsgeschichte Malakhov, V.V. 1994. Nematodes: structure, develofr of Kinorhyncha by examplc of the order Homalo- brian geology and paleontology. 11.Smithson. mise. von Halicryptus spinulosus Sieb. Zeitsehr. wiss. rhagida (Ccpha!orhyncha, Kinorhyncha). Zoo!. ment. classi/ication, und phylogeny. W. Duane Hope Col/ns .• 57: 109-144. Zooi .• 112: 525-571. Zhurn., 69(4): 5-14. Cfn Russian). (ed). 286 p. Washington & Loodon: Smithsonian Walcott, C. 1912. Middle Cambrian Branchiopoda. Hammond. R. 1967. Thc flnestruclurc of lhe lrunk and Institution Press. Malacostraca, Trilobita and Mcrosomata. Cambrian Adrianov, A.V. & Malakhov, V.V.199Ia. Thenervous pracsoma wall of Acimthocephalus ranae (Schrank May. H.G. 1919. Contributions to the life histories of geology and paleontology. 11. Smithson. mise.'. system of kinorhynchs (Cephalorhyncha, Kino- 1788) Lunc, 1911. Parasit%gy, 57: 475-486. Gordius rohustus Leidy and Paragordius varius Col/n .•.• 57: 145-228. rhyncha). Zool. Zhurn., 70(2): 5-12. (In RussianL Higgins, R.P. &. Krislensen, R.M. 1986. New Loricifera (l.eidy). BioL Monogr., 5: 1-119. Waicolt, C. 1931. Addenda to dcscriplion of Burgcss Adrianov, A.V. & Malakhov, V.V. 1991b. Body eayity from Southeastcrn Unitcd Stales coastal waters. Morse. M.P. 1981. Meiopriapu/us /ijiensis n. gen., n. Shalc fossils (with explanatory notes by C.E. Rcs- of Kinorhyncha. Dok/. Akad. Nauk SSSR, 317(2): Smithson. Contr. Zooi., 438: 1-70. sp.: an intcrstitial priapulid fro~ coarse sand in Fiji. ser). Smithson. mise. CoLlns., 85: 1-46. 506-509. On Russian). Higgins, R.P. &. Storch, V. 1989. Uilrastruclural obser- Trans. amer. Micr. Soc .• 100(3): 239-252. zapotosky, J.E. 1971. 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