Cymothoa

Martin, Melissa B., Bruce, Niel L. & Nowak, Barbara F., 2016, Review of the fish-parasitic genus Cymothoa Fabricius, 1793 (Crustacea: Isopoda: Cymothoidae) from Australia, Zootaxa 4119 (1), pp. 1-72 : 6

Key to the Australian species of the genus Cymothoa

1. Pereonite 1 anterolateral margins broad, with round or subtruncate projections; extending more than half the length of cepha- lon................................................................................................ 2

- Pereonite 1 anterolateral margins narrow, with minute projections; extending less than half the length of cephalon....... 5

2. Uropod half or shorter than pleotelson length; pereopod 7 ischium without bulbous protrusion on inferior distal margin... 3

- Uropod more than half of pleotelson length; pereopod 7 ischium with bulbous protrusion on inferior distal margin......... 4

3. Pereopod 7 merus with bulbous protrusion on inferior distal margin; pleonites not subequal in width..... Cymothoa eremita

- Pereopod 7 merus without bulbous protrusion on inferior distal margin; pleonites subequal in width..... Cymothoa frontalis

4. Frontal lamina ventrally folded, appearing to envelop paired antennae; pereopod 7 basis more than 1.0 times longer than wide, dactylus broad......................................................................... Cymothoa propria

- Frontal lamina not ventrally folded, not enveloping paired antennae; pereopod basis less than 1.0 times longer than wide, dac- tylus narrow............................................................................. Cymothoa indica

5. Body subparallel or elongate, more than 2.0 times as long as greatest width....................................... 6

- Body ovate or wide, less than 2.0 times as long as greatest width................................................ 9

6. Cephalon subtruncate, pleotelson posterior margin rounded................................................... 7

- Cephalon subtriangular, pleotelson posterior margin subtruncate............................................... 8

7. Pereonite 7 posterolateral margin not extending beyond pleonite 3; uropod exopod longer than endopod, pereopod 7 inferior margin smooth and straight on basis, ischium and merus.................................... Cymothoa bychowskyi

- Pereonite 7 posterolateral margin extending beyond pleonite 3; uropod exopod similar length to endopod, pereopod 7 inferior margin with bulbous protrusion on basis, ischium and merus................................... Cymothoa pulchrum

8. Labrum narrow and small, eyes absent....................................................... Cymothoa carangi

- Labrum fleshy, eyes partially or distinctly visible............................................... Cymothoa vicina

9. Pereonite 1 with bulbous ornamentation; anterolateral margin extending beyond cephalon anterior margin.............. 10

- Pereonite 1 without bulbous ornamentation; anterolateral margin partially reaching or reaching anterior margin of cephalon 11

10. Coxae 5–7 visible from dorsal view, posteroventral margins with acute carina; pleonite 5 wider than pereonite 7................................................................................................ Cymothoa hermani

- Coxae 5–7 not visible from dorsal view, posteroventral margins without acute carina; pleonite 5 wider than pereonite 7............................................................................................ Cymothoa rotunda

11. Pereonite 1 posterolateral margins with minute projections; pereopod 7 basis with acute carina, pleopod 1 exopod and endopod margins smooth....................................................................... Cymothoa epimerica

- Pereonite 1 posterolateral margins without minute projections; pereopod 7 basis without acute carina; pleopod 1 exopod and endopod margins irregular.............................................................. Cymothoa parupenei