;; 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