The terminology of larval cestodes or metacestodes

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10Table 4. System of nomenclature of cestode larval stages proposedby Gulyaev (1997a) based on that of Jarecka (1975) withevolutionary stages addedFirst intermediate hostMetacestodesSecond intermediate hostCercoid Metacercoids PostlarvaProcercoidCercoscolexPlerocercoidProtolarvaAmphicyst Tetrathyridium LarvacystoidCysticercus Blastocyst LarvacystCysticercoidcepted by the Shorter Oxford Dictionary and utilisedin zoological terms such as metamorphosis. Cercoidis a useful term in that it is a component of many ofthe names of known larval forms, but suffers from thedisadvantage that not all names (e.g. cysticercus) areformed from it. Because of differences of opinion, theneutral term larva is used in this review.(c) Freeman (1973) objected to Jarecka’s (1970)division of larval cestodes into cercoids and metacercoids(cercoids which have lost their cercomer) on thegrounds that many groups of cestodes do not possesscercomers in the early stages of development. Jarecka(1975) and Jarecka et al. (1981), however, have arguedthat, based on the earlier views of Janicki & Rosen(1917), all cestodes possess cercomers but they differin form. Jarecka et al. (1981) argued that the cercomersof procercoids, the cyst walls of cysticercoidsand the bladders of cysticerci are homologous, as theyall possess microvilli on their surfaces and they aretherefore modifications of the cercomer. An additionalpotential objection to the system of Jarecka (1975)would be that it does not deal with paratenic hosts,a phenomenon which is common within the Pseudophyllidea(e.g. Mueller, 1938; Robert et al., 1988) andin the Proteocephalidea (e.g. Biserkov & Genov, 1988;Biserkov & Kostadinova, 1997).(d) One particular term, cercoscolex, warrantsspecific comment as it has an extremely confusedusage. It was coined by Jarecka (1970a,b) for caudate,non-lacunate cestode larvae with invaginatedscoleces, which lose their cercomers in a secondintermediate host and was applied to the generaValipora, Paradilepis and Neogryporhynchus, currentlyincluded in the family Gryporhynchidae (seeSpasskii & Spasskaya (1973) for definition of theGryporhynchinae) thereby conforming with the usageby Leuckart (1876) and Villot (1883) under the term‘gryporhynchus’ or ‘gryporhynque’. In 1975, Jareckaexpanded the definition to include other acetabulatemetacestodes lacking a primary lacuna (e.g. Proteocephalidea)as well as those in which the primarylacuna was a transitory feature (Dipylidium). Jareckaet al. (1981) subsequently extended the term to includethe dilepidid genera Paricterotaenia and Anomotaenia,which have withdrawn scoleces and to anymetacestode with microtriches rather than microvillion the cyst wall. They subsequently asserted (Jareckaet al., 1984) that this metacestode was typical fordilepidids. Freeman (1973) by contrast used the termprecysticercoid for the metacestodes of Choanotaeniaand other related dilepidid genera. Gabrion & Helluy(1982) reviewed the morphogenesis of metacestodesof the Dilepididae and concluded that the term monocercusof Villot (1883) applied to 31 dilepidid speciesin which an elongate cercomer disintegrated into globuleswhich persist in the metacestode. They consideredthat the monocercus was characteristic of the Dilepididae.The terminology applied to metacestodes of theDilepididae is therefore particularly complex.More recent additionsMore recent modifications to these systems of terminologyare essentally restricted to cysticerci andcysticercoids. However, significant advances in understandingof the life-cycles of terabothriideans,in which the larval stage was recognised as auniacetabulo-plerocercoid (Hoberg, 1987; Galkin,1996), have also been made without the introduction
11Table 5. Nomenclature employed by Freeman (1973) to describe the larval stages of cestodes, as modified byUbelaker (1983).Cestode taxon Definition ExampleTermHymenolepididae/Anoplocephalidae/Davaineidae/Dilepididaerostello-cysticercoidwith rostellumarostello-cysticercoid no rostellum Anoplocephalinaeanacanthorostello-cysticercoid without hooks Hymenolepis diminutaacanthorostello-cysticercoid with hooks Hymenolepis nanacaudate-cysticercoidwith cercomeracaudate-cysticercoidwithout cercomerlongicaudate-cysticercoid with long cercomer Drepanidotaenia lanceolatabrevicaudate-cysticercoid with short cercomer Raillietina spp.circumcaudate-cysticercoidAploparaksis spp.micranthorostello-cysticercoid with small hooks Davainea proglottinaprecysticercoidChoanotaenia spp.Taeniidaeheteracantho-cysticercustwo rows of dissimilar hooks Taenia soliumhomeacantho-cysticercus hooks similar Fossor, Monorodotaeniaanacantho-cysticercus lacking hooks Taenia saginatastrobilo-cysticercus segmentation in metacestode Taenia taeniaeformis, T. polyacanthamulticephalo-cysticercus multiple scoleces Taenia serialisGryporhynchidaeacanthacetabulo-plerocercoidLinstowiinaeprecysticercusMesocestoididaeinvaginated acetabulo-plerocercoidValiporaOochoristicaMesocestoidesNippotaeniideauni-acetabulo-plerocercoidProteocephalideaglandacetabulo-plerocercoidOphiotaenia filaroidesinvaginated acetabulo-plerocercoid plerocercoid I Corallotaenia minutamet-acetabulo-plerocercoid plerocercoid IIculci-acetabulo-plerocercoidProteocephalus parallacticusPseudophyllideaacaudate bothrio-plerocercoidstrobilobothriate-plerocercoidEubothrium salveliniDiphyllobothrium dendriticumHaplobothriideatentaculo-plerocercoidCaryophyllideacaudate post-plerocercoidSpathebothriidea(a)caudate–adultArchigetes, CaryophyllaeusCyathocephalus, BothrimonusTetraphyllideabothrio - plerocercoidTrypanorhynchatentaculo - plerocercoidneoplerocercoidLacistorhynchus tenuis
Page 1 and 2: Systematic Parasitology 52: 1-33, 2
Page 3 and 4: 3inum (= Taenia cucumerina). Both L
Page 5 and 6: 5Table 1. Names of larval cestodes
Page 7 and 8: Figure 2. Schematic representation
Page 9: 9Table 3. Comparison of the systems
Page 13 and 14: 13broad and elongate cercomer in co
Page 15 and 16: 15from which cysticercoids bud off.
Page 17 and 18: 17ing species are Choanotaenia infu
Page 19 and 20: 19characters upon which a system of
Page 21 and 22: 21Figure 4. Schematic representatio
Page 23 and 24: 23Table 6. Suggested terms for larv
Page 25 and 26: 25new difficulties for this system
Page 27 and 28: 27fimbriocercus (including armatetr
Page 29 and 30: 29Burt, M.D.B. (1962) A contributio
Page 31 and 32: 31host Branchinecta gaini Daday (Br
Page 33: 33Stunkard, H.W. (1937) The life cy

The terminology of larval cestodes or metacestodes

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