Only 8 amphilinid species are known. The amphilinids are large worms (several cm long) which,in contrast to the true tapeworms (Eucestoda), have a flattenedleaf-like body that is not divided into proglottids (false "segments").Larvae have 10 peculiarly shaped hooks of several types at theposterior end, which are retained by the adult. They are parasitesin the body cavity of freshwater and marine teleost fishes andfreshwater turtles (Dubinina, 1982). They have little economicsignificance, although one species was shown to affect sturgeon,the producers of caviar, adversely. Amphilinids are of considerableinterest to biologists, because they may cast light on the phylogenyof tapeworms and of related forms. Most studies deal with thetaxonomy as well as the light- and electron microscopic structureof a few species.Life cycles are known only for a few species and little is known of their effects on the host.

A key to the species of Amphilinidea is available here.

The genus and species names listed first are those from Dubinina (1982). They are used in the text, because they are supported by the best descriptions and widely used in the literature. The names proposed by Bandoni and Brooks (1987), which are used in the tree, are here marked with an asterisk.

Amphilina foliacea*

synonyms Monostomum foliaceum, Amphilina neritina

Amphilina japonica*

synonyms A. bipunctata, A. foliacea

Gephyrolina paragonopora

synonyms Amphilina paragonopora, Hunteroides mystel, Schizochoerus paragonopora*

Schizochoerus liguloideus*

synonyms Monostomum liguloideum, Amphilina liguloidea

Nesolecithus janickii

synonyms Amphilina liguloidea, Monostomum liguloideum, Schizochoerus janickii*

Nesolecithus africanus

synonym Schizochoerus africanus*

Austramphilina elongata

synonyms Kosterina Kuiperi, Gigantolina elongata*

Gigantolina magna*

synonyms Amphilina magna, Gyrometra albotaenia, Gyrometra kunduchi

The Amphilinidea are large (several cm long), hermaphroditic, non-”segmented” flatworms whose adult stages live in the body cavity of turtles and teleost fish and use crustaceans as intermediate hosts. More detail is available on the Life cycles page. They have 10 hooks of several types at the posterior end (Fig.1), and a posteriorly located large seminal receptacle and ovary.

Figure 1. Hooks of larval Amphilina foliacea. a. Arrangement of hooks in the larva, b. Shape of hooks in greater detail (redrawn from Dubinina, 1982).

The uterus extends from the ovary to the anterior end, back again to the posterior end, and forward to open at the anterior end. Small follicular yolk glands and testes are scattered over large parts of the body. Amphilinids lack an intestine (Fig. 2).

Figure 2. Juvenile Amphilina foliacea. Note uterine opening at anterior end, and vaginal and male pores at posterior end (redrawn from Dubinina, 1982).

For more information see Structure of the larva and Structure of the juvenile and adult pages.

View Amphilinidea Tree

Phylogeny of Amphilinidea (single family Amphilinidae) (according to Bandoni and Brooks, 1987).
See section on synonyms for alternativenomenclature.

Bandoni and Brooks (1987) have revised the Amphilinidea and made the first and only analysis of the group using phylogenetic systematics (cladistics). The analysis of 46 character states of 30 morphological (light-microscopic) characters produced the tree illustrated above. They distinguish three genera with altogether eight species, mainly based on the shape of the uterus (N-shaped or looped), shape of the body (elliptical, fusiform or elongate), whether vagina crossing or not crossing male duct, distribution of the testes and whether testes paired or not paired, whether vagina simple or bifurcate, shape of ovary, whether gonopore separate or common. Important characters, such as the structure of the protonephridial system, are not included, and the tree will almost certainly have to be revised using additional characters.

Gibson (1994) has given a key to the species (see also Schmidt, 1986), and Dubinina (1982), in her detailed monograph of the Amphilinidea, has discussed the position of the group in the phylum Platyhelminthes.