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Key to the Species of Amphilinidea

Klaus Rohde

Dubininaís (1982) monograph is based on a detailed anatomical and histological examination of the various species, which permits, for example, the distinction of a simple seminal receptacle and an accessory seminal receptacle. The key presented here is therefore based on Dubinina (1982), although it was strongly modified taking into account my own studies as well as the keys of Gibson (1994) and Bandoni and Brooks (1987).

Dubinina (1982) recognized four families, the Amphilinidae with two subfamilies, the Amphilininae (genus Amphilina) and Gephyrolininae (genus Gephyrolina), the Schizochoeridae (genera Schizochoerus and Nesolecithus), the Austramphilinidae (genus Austramphilina), and the Gigantolinidae (genus Gigantolina). Gibson (1994) distinguished two families, the Amphilinidae and Schizochoeridae, the former including the genus Amphilina, the latter the two subfamilies Schizochoerinae (genera Gephyrolina, Nesolecithus and Schizochoerus) and Austramphilinae (genera Austramphilina and Gigantolina). Differences between species of the families appear to be very slight. Furthermore, an egg stalk is found in genera included by Gibson in two families, i.e., in Amphilina and Gephyrolina (but in none of the others). Hence only a single family, Amphilinidae, is recognized here. Bandoni and Brooks (1987) synonymized Austramphilina with Gigantolina, and Nesolecithus and Gephyrolina with Schizochoerus. Further studies, particularly of the excretory system, egg and early cleavage, are necessary to justify these synonymizations, particularly in view of the fact that a polar egg stalk is present only in Amphilina and Gephyrolina, but not in any of the other genera, and that there are significant differences in the structure of the reproductive system of Austramphilina and Gigantolina. For a list of synonyms of the genus and species names used in the following see Synonyms.


1.      Eggs with stalk at one pole. Vagina with simple seminal 
        receptacle opening into terminal part of oviduct in front of 
        its opening into the ootype. The first ascending and the 
        descending coils of the N-shaped uterus located on one side 
        of the body, the second ascending coil located on the other
        (Figure 1). 
        .............................................................2	

Figure 1. Arrangement of uterine coils (red) in species of Amphilina. Note location of first ascending and descending coils to one side of midline, and of second ascending coil to the other. Redrawn from Dubinina (1982), copyright © 1982 Nauka Publishers.
		
1'.     Eggs lack a polar stalk. Vagina, in addition to a seminal 
        receptacle, possesses a large accessory seminal receptacle 
        (except for Austramphilina which has an undivided 
        seminal receptacle). Uterus of different shape. .............4


2(1).   Body shape oval leaf-like. Proboscis relatively weakly 
        developed, without specialized musculature. Testes 
        distributed in lateral fields extending between uterine 
        coils. Unpaired vitelline duct ascending. Ovary deeply 
        lobed, fan-like. Excretory system reticular, without 
        longitudinal excretory ducts. Parasites of holarctic 
        sturgeons (Acipenseridae). ......................3 (Amphilina)


2'.     Body elongate, proboscis strongly developed, with 
        specialized radial musculature. Testes located directly on 
        sperm ducts, lateral to uterine coils. Unpaired vitelline 
        duct descending. Deeply lobed ovary of irregular elongate 
        shape. Excretory system with two longitudinal lateral ducts. 
        Parasites of siluroid fishes in India. 
        ......................................Gephyrolina paragonopora

3(2).   Testes irregularly distributed between uterine coils. 
        External opening of vagina some distance lateral to the 
        terminal male gonopore. Vagina crosses male duct at the 
        level of the terminal part of the sperm duct, anterior to 
        the ejaculatory bulb. Parasite of palearctic sturgeons. 
        ............................................Amphilina foliacea


3'.     Testes concentrated in the lateral fields of the body, 
        lateral to uterine coils, only a few extending between the 
        coils near posterior end of body. External vaginal opens 
        directly beside the terminally located male pore. Vagina 
        crosses male gonoduct at the level of ejaculatory duct, 
        posterior to ejaculatory bulb. Parasite of sturgeons of the 
        Amur region, Japan and North America. ......Amphilina japonica

4(1').  First ascending and descending coils of N-shaped uterus 
        symmetrically arranged on both sides of the body relative to 
        midline, terminal ascending part located lateral to 
        descending part. Accessory seminal receptacle tube-like. 
        Distal part of vagina branches and opens to the outside 
        through one ventral and one dorsal pore. ....................5
  
        
4'.     First ascending and descending coils of uterus located 
        symmetrically on both sides of the body relative to midline, 
        second ascending coil between them. Accessory seminal 
        receptacle sac-like. Distal part of vagina opens to the 
        outside through single pore. ................................7

5(4).   Body elongate, leaf-like. Accessory seminal receptacle 
        reaches approximately 1/3 body length. 
        .....................................Schizochoerus liguloideus


5'.     Body oval leaf-like. Accessory seminal receptacle reaches 
        approximately 1/6 body length. ...............6 (Nesolecithus)

6(5').  Vitelline glands extend further anteriorly than testes. 
        Accessory seminal receptacle without narrow basal part, of 
        equal width along its whole length. Vagina short, its length 
        from distal branching to accessory seminal receptacle equal 
        to diameter of ovary. Parasite in body cavity of Arapaima
       gigas (Clupeiformes) in the Amazon. 
        .........................................Nesolecithus janickii


6'.     Testes extend further anteriorly than vitelline glands. 
        Accessory seminal receptacle with basal narrow and distal 
        swollen part. Vagina elongate, several times longer than 
        diameter of ovary. Parasite in body cavity of Gymnarchus
       niloticus (Mormyriformes) in West Africa (Nigeria). 
        .......................................Nesolecithus  africanus

7(4').  Joint external opening of vagina and male gonoduct (common 
        gonopore). Ovary not lobed, irregularly bean-shaped, lateral 
        to anterior part of accessory seminal receptacle. Frontal 
        glands consist of many cells and are restricted to anterior 
        end of body, single ducts open directly at level of 
        proboscis. Eggs ellipsoid. ............Austramphilina elongata


7'.     External opening of vagina dorsal, short distance in front 
        of terminal male gonopore. Ovary deeply lobed, with two 
        wings, medial, posterior to accessory seminal receptacle. 
        Frontal gland cells concentrated around a common duct which 
        begins at anterior margin of accessory seminal receptacle 
        and opens anteriorly in apical deepening. Eggs spherical. 
        .............................................Gigantolina magna
        

References

Bandoni, S.M. and Brooks, D.R. (1987). Revision and phylogenetic analysis of the Amphilinidea Poche, 1922 (Platyhelminthes: Cercomeria: Cercomeromorpha). Canadian Journal of Zoology 65:1110-1128.

Dubinina, M. N. 1982. Parasitic worms of the class Amphilinida (Platyhelminthes). "Nauka", Leningrad (in Russian). (Older references therein).

Gibson, D. I. 1994. Order Amphilinidea Poche 1922. In "Keys to the Cestode Parasites of Vertebrates" (L. F. Khalil, A. Jones and R. A. Bray, eds.) CAB International. Wallingford, pp. 3-10.

Rohde, K. 1994. The minor groups of parasitic Platyhelminthes. Advances in Parasitology 33:145- 234.

About This Page

Klaus Rohde
University of New England, Armidale, New South Wales, Australia

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