Nerocila exocoeti Pillai, 1954

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 : 50-52

Nerocila exocoeti Pillai, 1954

( Fig. 8 a–c)

Nerocila exocoeti Pillai, 1954: 12–13 .— Kurochkin, 1980: 289.— Bruce, 1987b: 404.— Bruce & Harrison-Nelson, 1988: 592, fig. 4.— Bruce & Bowman, 1989: 1.— Trilles, 1994: 89.— Kensley, 2001: 233.— Trilles, Ravichandran & Rameshkumar, 2011: 451.— Sivasubramanian, Ravichandran, Rameshkumar & Allayie, 2011: 99–101 figs 1–4.— Trilles, Rameshkumar & Ravichandran, 2013: 1273–1286, figs 2c, 7a–i, 8, 9.— Aneesh, Helna, Valarmathi, Chandra & Mitra, 2017c: 385–394, figs 1–7 .

Nerocila madrasensis Ramakrishna & Ramaniah, 1978: 177 –180, figs 1–3.

Type and type locality. The neotype, deposited at National Museum of Natural History, French ( MNHN IU- 2009- 1937), from Parangipettai, the Southeastern coast of India, on Exocoetus volitans .

Material examined. Neotype: 1 ovig. female (28 mm), Parangipettai, 12 April 2011, from Exocoetus volitans , coll. G. Rameshkumar. (MNHN-IU-2009-1937).

Non-type: 3 ovig. females, (24–28 mm), Pazhaiyar, 28 December 2016, from Parexocoetus brachypterus , coll. P. Vigneshwaran ( CAS / MBRM 500–502); 1 ovig. female (28 mm), Parangipettai, 22 July 2017, from Exocoetus volitans , coll. S. Ravichandran ( ZSI / MBRC D1-542 ) ; 2 non-ovig. females (22, 24 mm), Parangipettai, 12 April 2011, from Exocoetus volitans , coll. G. Rameshkumar ( CAS / MBRM 506 , 507 ) Southeastern coast of India.

Remarks. Trilles et al. (2013) redescribed and diagnosed N. exocoeti from the female neotype (MNHN-IU-2009-1937). N. exocoeti can be identified by coxae 2–4, often visible in dorsal view, produced into rounded processes, not exceeding beyond posterior of pereonites; coxae 5–7, much longer than the anterior, posterior margin acute, reaching or extending slightly or distinctly beyond posterior of pereonites. Pleotelson long as wide, lateral margins convex, converging to an indistinct apical point, and that the entire body is blackish blue in color with many chromatophores.

Nerocila exocoeti was identified by Pillai (1954) from a large number of specimens in all stages of development collected on Parexocoetus brachypterus from Travancore, India. However, no figures have been published. The author specified only that the main distinguishing character of this species is the comparative size of the coxal plates, the second being small, not extending beyond the posterior border of the segment and the seventh reaching the tip of the first pleon segment, and that the entire body is steel blue in color. Males were collected but not described by Pillai (1954). N. exocoeti was later collected on P. brachypterus and Scomberomorus multiradiatus (gut contents?) from Papua New Guinea, Indonesia, and Taiwan by Bruce & Harrisson-Nelson (1988). Only N. exocoeti and N. trichiuri have been collected from fishes belonging to the family Exocoetidae and both of these species are readily distinguished from each other. In N. exocoeti the uropods are much longer, exopod and endopod extending far beyond the distal margin of pleotelson. In N. trichiuri the coxae and postero-lateral angles of pereonites bluntly rounded and the live specimens of N. trichiuri are pale in colour.

Nerocila madrasensis was poorly described by Ramakrishna & Ramaniah (1978) who suggested that this species resembles to N. serra and N. trichiura . Possibly related to N. trichiura according to Bruce (1987a), N. madrasensis and N. trichiura were provisionally synonymized by Trilles (1994) and Trilles et al. (2011). Recently N. madrasensis has been considered as a junior synonym of N. exocoeti based on the type specimen by Aneesh et al. (2017c).

Colour. The entire body is steel blue in colour withmany chromatophores ( Pillai, 1954).

Size. Non-ovig. females 24–28 mm; ovig. females 22–24 mm.

Distribution. This species extended from southem India ( Pillai 1954; Trilles et al. 2013; Aneesh et al. 2017c) to Papua New Guinea, Indonesia, and Taiwan (Bruce & Harrisson-Nelson 1988).

Host. Only known from the beloniform hosts family Exocoetidae : Parexocoetus brachypterus ( Pillai 1954; Bruce & Harrisson-Nelson 1988), Exocoetus volitans ( Sivasubramanian et al. 2011; Trilles et al. 2013) and family Hemiramphidae : Hemiramphus sp. (Ramakrishna & Ramaniah 1978) and Rhynchorhamphus malabaricus Collette, 1976 ( Aneesh et al. 2017).

Figures

FIGURE 1. a–c, Anilocra dimidiata Bleeker, 1857, female (24 mm), (ZSI/MBRC D1-529); d–f, Catoessa boscii (Bleeker, 1857), female (17 mm), (ZSI/MBRC D1-530); g–i, Ceratothoa angulata (Richardson, 1910), female (29 mm), (ZSI/MBRC D1-533); j–l, Cymothoa bychowskyi Avdeev, 1979, female (27 mm), (CAS/MBRM C-87); m–o, Cymothoa eremita (Brünnich, 1783), female (29 mm), (ZSI/MBRC D1-532); p–r, Cymothoa frontalis Milne Edwards, 1840, female (25 mm), (CAS/MBRM C-89).

FIGURE 2. a–c, Cymothoa indica Schiöedte & Meinert, 1884, female (25 mm), (CAS/MBRM C-97); d–f, Cymothoa parupenei Avdeev, 1979, female (25 mm), (ZSI/MBRC D1-533); g–i, Glossobius impressus (Say, 1818) female (26.7 mm) (ZSI/MBRC D1-554); j–l, Joryma hilsae Rameshkumar et al. 2011, female (20 mm), (ZSI/MBRC D1-535); m–o, Joryma sawayah Bowman & Tareen, 1983, female (14 mm), (ZSI/MBRC D1-536); p–r, Lobothorax typus Bleeker, 1857, female (23 mm), (ZSI/MBRC D1-537).

FIGURE 3. a–c, Mothocya collettei Bruce, 1986, female (25 mm), (CAS/MBRM C-149); d–f, Mothocya melanosticta (Schiöedte & Meinert, 1884), female (24 mm), (ZSI/MBRC D1-538); g–i, Mothocya plagulophora (Haller, 1880), female (28 mm), (ZSI/MBRC D1-539); j–l, Mothocya renardi (Bleeker, 1857), female (30 mm), (ZSI/MBRC D1-540); m–o, Nerocila arres Bowman & Tareen, 1983, female (28 mm), (CAS/MBRM 475–476); p–r, Nerocila depressa Milne Edwards, 1840, female (30 mm), (ZSI/MBRC D1-541).

FIGURE 4. Mothocya plagulophora (Haller, 1880), female (28 mm), (ZSI/MBRC D1-539). a, dorsal view; b, lateral view; c, mouthpart with antennula and antenna; d, antennula; e, antenna; f, mandible; g, maxillula; h, maxilliped; i, maxilla.

FIGURE 5. Mothocya plagulophora (Haller, 1880), a, male (13 mm) (CAS/MBRM C-167) dorsal view; b–m, female (28 mm), (ZSI/MBRC D1-539); b–f, pereopod 1, 2, 4, 6 & 7; g–k, pleopods 1–5; l, uropod; m, brood pouch.

FIGURE 6. Nerocila depressa Milne Edwards, 1840, female (30 mm), (ZSI/MBRC D1-541). a, dorsal view; b, lateral view; c, forns; d, antennula; e, antenna; f, mandible; g, maxillula; h, maxilla; i, maxilliped.

FIGURE 7. Nerocila depressa Milne Edwards, 1840, female (30 mm), (ZSI/MBRC D1-541). a–e, pereopods 1–3, 5 & 7; f–j, pleopods 1–5; k, uropod.

FIGURE 8. a–c, Nerocila exocoeti Pillai, 1954, female (25 mm), (ZSI/MBRC D1-542); d–f, Nerocila longispina Miers, 1880, female (22 mm), (ZSI/MBRC D1-543); g–i, Nerocila loveni Bovallius, 1887, female (20 mm), (ZSI/MBRC D1-544); j–l, Nerocila phaiopleura Bleeker, 1857, female (26 mm), (ZSI/MBRC D1-545); m–o, Nerocila poruvae Rameshkumar et al. 2011, female (24 mm), (ZSI/MBRC D1-546); p–r, Nerocila serra Schiöedte & Meinert, 1881, female (28 mm), (CAS/MBRM–661).