Potamopyrgus antipodarum

Hechinger, Ryan F., 2012, Faunal survey and identification key for the trematodes (Platyhelminthes: Digenea) infecting Potamopyrgus antipodarum (Gastropoda: Hydrobiidae) as first intermediate host, Zootaxa 3418, pp. 1-27 : 5-6

Key to trematodes infecting Potamopyrgus antipodarum as first intermediate host

[Species number in brackets preceding name matches numbering in Fig. 1 and Table 1, and the ordering in the species accounts section.]

1. Lacking daughter parthenitae (sporocysts or rediae), free embryos appear to develop directly to over 100 spherical metacercariae that fill much of visceral mass................................................. [13] Microphallus sp. “livelyi”

- With parthenitae...................................................................................... 2

2. Cercariae lacking tail, with oral stylet.......................................... [15] Acaudate xiphidiocercaria sp. I

- Cercariae with tail (small cup-like, simple, forked, finned or bristled); with or without stylet.......................... 3

3 Tail small and cup-like (not more than 2x long as wide); stylet with two anterior points…........[11, 12] Coitocaecum spp.

- Tail elongate (e.g.,> 3x long as wide); if stylet present, lacking two anterior points.................................. 4

4 Tail forked........................................................................................... 5

- Tail not-forked........................................................................................ 7

5 Tail stem and furcae each about same length as body............................................ [1] Apatemon sp. I

- Tail stem at least 2x body length; caudal furcae short (much less than 1/2 stem length).................. (aporocotylids) 6

6 Cercaria smaller than 6b (body <100 long, tail stem <200 long); sporocysts round to slightly oblong.. [2] Aporocotylid sp. I

- Cercaria larger than 6a (body> 130 long, tail stem> 200 long); sporocysts elongate................ [3] Aporocotylid sp. II

7 Cercaria with oral stylet (may be minute & non-descript—see Plagiorchioid sp. I).................................. 8

- Cercaria lacking oral stylet............................................................................. 11

8 With virgula organ (sack-like organ in posterior oral sucker).................................................... 9

- Lacking virgula organ................................................................................. 10

9 Cercaria smaller than 9b (body <100 long), virgula organ wider than long, faintly bipartite or not bipartite.[16] Virgulate sp. I

- Cercaria larger than 9a (body> 130 long); virgule organ longer than wide, clearly bipartite............ [17] Virgulate sp. II

10 With prominent ventral sucker, Y-shaped bladder, small bullet-shaped stylet (less than 1/5 oral sucker length), and obscuring cystogenous glands throughout most of body.............................................. [18] Plagiorchioid sp. I

- Lacking ventral sucker, with elongate stylet (> ½ oral sucker length); body translucent with prominent penetration glands just posterior to equator............................................................[14] Microphallus sp. “poulini”

11 With pigmented eyespots.............................................................................. 12

- Lacking pigmented eyespots............................................................................ 17

12 With ventral sucker................................................................................... 13

- Lacking ventral sucker................................................................................ 15

13 Tail simple, not ornate............................................................. [19] Gymnocephalous sp. I

- Tail with lateral bristles................................................................... (lepocreadiids) 14

14 With 4 pairs of penetration glands................................................... [8] Stegodexamine anguillae

- With 6 pairs of penetration glands........................................................ [9] Lepocreadiid sp. II

15 Lacking dorso-ventral tail fin; sometimes with medial eye....................................[5, 6] Notocotylus spp.

- With dorso-ventral tail fin.............................................................................. 16

16 With penetration glands (gland bodies just pre-equator and gland ducts empty at anterior oral sucker); lacking longitudinal pig- ment bands..................................................................... [10] Telogaster opisthorchis

- Lacking penetration glands; with two longitudinal pigment bands........................... [7] Pronocephaloid sp. IV

17 Lacking ventral sucker; tail simple; body filled with opaque cystogenous glands (white with reflected light); prominent lateral arms of excretory system connect anteriorly; smaller than 17b (body length ~500)................[4] Pronocephaloid sp. I

- With ventral sucker; tail with dorso-ventral fin; larger than 17a (body length ~1000)…......... [20] Gymnocephalous sp. II

Figures

FIGURE 1. General characteristics of the parthenitae and cercariae of the trematodes infecting Potamopyrgus antipodarum as first intermediate host. Microphallus sp. “ livelyi ” (sp. 13), whose embryos develop directly to metacercariae, is not figured. Species numbers and codes follow Table 1 and species accounts. Cercariae are all to scale, with additional magnified views of three small cercariae (indicated by dashed lines). Parthenitae are not to scale. Scale bars consistently indicate 100 µm.