Nerocila, Leach, 1818

Ravichandran, S., Vigneshwaran, P. & Rameshkumar, G., 2019, A taxonomic review of the fish parasitic isopod family Cymothoidae Leach, 1818 (Crustacea: Isopoda: Cymothooidea) of India, Zootaxa 4622 (1), pp. 1-99 : 45-46

Key to the Indian species of Nerocila

1. Coxae 2–4, often visible in dorsal view, produced into rounded processes, longer than respective segment............... 2

- Coxae 2–4, not visible in dorsal view, produced into acute processes, shorter than respective segment.................. 3

2. Pereonites 7 posterior angles well produced reaching pleonites 5; antennula extending to pereonite 1................... 4

- Pereonites 7 posterior angles lesser produced reaching pleonites 1; antennula not extending to pereonite 1............... 5

3. Pereonites 1–6 posterior angled away from the body, pointed process.................... Nerocila loveni Bovallius, 1887

- Pereonites 1–6 posterior angles not produced, acute process............................. Nerocila exocoeti Pillai, 1954

4. Uropod exopod straight, exopod about 2.5 times longer than endopod; mandible palp with setae on distolateral margin of article 2......................................................................... Nerocila trichiura ( Miers, 1877)

- Uropod exopod curved, 0.5 times longer than endopod; mandible palp without setae on distolateral margin of article 2........................................................................ Nerocila serra Schiöedte & Meinert, 1881

5. Body about 2.5 times as long as wide, widest between pereonites 4–7; pleonites 3–5 rounded, not produced............. 6

- Body about 2.8 times as long as wide, widest between pereonite 5–6; pleonites 3–5 lateral partially acute, produced............................................................................ Nerocila depressa Milne Edwards, 1840

6. Pereopods 6–7 subequal in length, with dactylus longer than propodus; antenna with10 articles, without setae............ 7

- Pereopods 6–7 decreasing in length respectively, with dactylus smaller than propodus; antenna with11 articles, 3–11 with setae............................................................... Nerocila poruvae Rameshkumar et al. 2011

7. Eyes small and distinct; cephalon anterior margin rounded.............. Nerocila recurvispina Schiöedte & Meinert, 1881

- Eyes large and almost indistinct; cephalon anterior margin with slender medial point................................ 8

8. Pleopods 1–2 with five coupling hooks on protopod medial margin; endopod 3–4 with few folds...................... 9

- Pleonites 1 and 2 with ventrolateral margins weakly produced; pereopod 7 with a row of 2 spines on posterior margin of propodus.............................................................................................. 10

9. Pleonites 1–2 with ventrolateral margins strongly produced; pereopod 7 with a row of 7 spines on posterior margin of propodus................................................................................................ 11

- Pleopods 1–2 without coupling hooks on protopod medial margin; endopod 3–4 with large folds................................................................................................. Nerocila longispina Miers, 1880

10. Uropod endopod with very deep notch on medial margin; serrate with lateral margin. Nerocila arres Bowman & Tareen, 1983

- Uropod endopod with not notch on medial margin; not serrate with lateral margin...... Nerocila phaiopleura Bleeker, 1857

11. Pleotelson long or as wide as long, posterior margin rounded, without caudomedial lobe................................................................................................. Nerocila sigani Bowman & Tareen, 1983

- Pleotelson wide, posterior margin subtruncate with caudomedial lobe................... Nerocila sundaica Bleeker, 1857