Nerocila depressa Milne Edwards, 1840

Nerocila depressa Milne Edwards, 1840 View in CoL View at ENA

( Figs 3 View FIGURE 3 p–r, 6, 7)

Nerocila depressa Milne Edwards, 1840: 254 View in CoL , pl. 31 ( figs 17–21 View FIGURE 17 View FIGURE 18 View FIGURE 19 View FIGURE 20 View FIGURE 21 ).— White, 1847: 108.— Schiöedte & Meinert, 1881: 15, pl. 1 (figs 10, 1l).— Stebbing, 1893:351.— Lanchester, 1900: 265, pl. XII (fig. 5).— Thielemann, 1910:33.— Nierstrasz, 1931:124.– Trilles, 1975: 318, pl. II (fig. 13); 1979: 251.— Bruce, 1987b: 404, fig. 34e. — Bruce & Harrison-Nelson, 1988: 591, fig. 3.— Kazmi, Schotte & Yousuf, 2002: 105, fig. 91.— Trilles, Ravichandran & Rameshkumar, 2011: 451.— Printrakoon & Purivirojkul, 2011: 322–326, figs 2–4.— Trilles, Rameshkumar & Ravichandran, 2013: 1273–1286, fig. 2b.— Rameshkumar, Ravichandran & Ramesh, 2014c: 124–128, fig. 2.

Nerocila dolichostylis Koelbel, 1879:411 , pl. II (fig. 3 a–b).— Bruce, 1987c: 404.

Nerocila pigmentata Bal & Joshi, 1959: 565 View in CoL , pl. 2 ( figs 6–10 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 ).— Bruce, 1987b: 406.

Nerocila pigmenta .—Bal & Joshi, 1960: 446.

Not Nerocila pigmentata .— Parimala, 1984: 180–181, fig. 1 (= Nerocila sp.?).

Type and type locality. The type locality is not known. The specimen at the MNHN (Is. 508), believed to be the type specimen, is in very poor condition ( Bruce 1987b) .

Material examined. 4 ovig. females (20–23 mm), Pazhaiyar , 25 January 2011, from Sardinella gibbosa (Bleeker, 1849) , coll. G. Rameshkumar ( CAS / MBRM 460 –463) ; 2 non-ovig. females (19, 23 mm) Nagapattinam , 22 July 2016, from C. malabaricus , coll. P. Vigneshwaran ( CAS / MBRM 464 , 465 View Materials ) ; 1 ovig. female (25 mm), Pazhaiyar , 28 December 2016, from Selaroides leptolepis (Cuvier, 1833) , coll. S. Ravichandran ( ZSI / MBRC D1-541 ) , all are collected from Southeastern coast of India.

Description female. Body about 2.8 times as long as wide, widest between pereonites 5–6. Cephalon anterior margin rounded. Eyes with facets almost indistinct; 0.5 width of cephalon. Pereonites 1 and 5–7 longest, 2–4 subequal; pereonite 7 sometimes slightly shortest, and posterolateral angles of pereonite 7 produced backward into a pointed process; posterior angles of pereonites 1–6 not produced. Coxae of pereonite visible in dorsal view, coxae 2–7, often produced into rounded processes, partialy exceeding beyond posterior of pereonites, coxae 5–7, much more long than the anterior, posterior margin acute, reaching or extending distinctly beyond posterior of pereonites. Pleonites visible in dorsal view, pleonites 1 and 2 longest, pleonite 5 shortest and widest, pleonies 3 and 4 subequal; ventrolateral margins of pleonites 1 and 2 posteriorly directed and acute, extending to pleonites 3–5, respectively; pleonites 3–5 lateral partially acute. Pleotelson 0.8 as long as wide, lateral margins curving to medial point.

Antennula composed with 8 articles, articles 4–8 each with posterodistal cluster of esthetes. Aantenna slightly smaller than antennula with 9 articles, articles 4, 5, 8 and 9 with setae. Mandible palp article 1 largest and article 3 without setae on distolateral margin. Maxillula with 3 terminal spines. Maxilla with 5 spines on medial lobe and one spine on lateral lobe. Maxilliped with oostegial lobe, distal palp segment with five terminal spines.

Pereopods gradually increase in size from 1–7, without marginal robust setae, dactylus longer than propodus. Pleopods 1 and 2 with five coupling hooks on protopod medial margin; pleopod 2 with appendix masculine about 0.5 length of endopod; endopod proximomedial lobe well-developed but not folded; endopods 3–5 with proximomedial lobe well-developed, folded; pleopods endopod 3 and 4 with a single fold or two fold, pleopod endopod 5 with several large folds.

Uropod slender, tapering, exopod about two times longer than endopod; endopod reaching or extending scarcely beyond the posterior margin of pleotelson; exopod extending by far beyond endopod.

Colour. Body pale tan, latral part of pleon and uropods dark.

Size. Ovig. females 20–25 mm; non-ovig. females 19–23 mm.

Remarks. Nerocila depressa can be identified by the coxae and posterolateral comers of the pleonites are posteriorly directed and are not bent dorsally. Ventrolateral margins of pleonites 1 and 2 posteriorly directed and acute, extending to pleonites 3–5 respectively, lateral margins of pleotelson curving to a medial point.

Nerocila depressa and Nerocila loveni are similar in having a pereonites 1 and 5–7 longest, 2–4 subequal; pereonite 7 sometimes slightly shortest, and posterolateral angles of pereonite 7 produced backward into a pointed process; posterior angles of pereonites 1–6 not produced. Differences include the Nerocila depressa having the coxae and posterolateral comers of the pleonites are posteriorly directed and are not bent dorsally.

Trilles (1975) stated that Nerocila pigmentata Bal & Joshi, 1959 was similar to N. depressa and considered the species to be synonymous with N. depressa , his later being accepted by many authors ( Bruce 1987b; Bruce & Harrison-Nelson 1988; Trilles 1994; Trilles et al. 2011). Besides that, the species identified by Parimala (1984) as N. pigmentata is of uncertain identity and clearly not N. depressa (Bruce & Harrisson-Nelson 1988) .

Distribution. The species has been recorded from the northern Indian and Pacific oceans with a probable range from India eastwards to Hong Kong ( Bal & Joshi 1959; Bruce, 1988; Printrakoon & Purivirojkul 2011; Trilles et al. 2013; Rameshkumar et al. 2014c).

Hosts. This species previously recorded from Coila dussumieri , Engraulis sp. both Engraulididae ; Cyclocheilichthys apogon (Cyprinidae) . Bal & Joshi (1959) recorded the host Opisthopterus turtoor (as O. tardoore ). Latterly recorded from the family Clupeidae : Sardinella fimbriata ( Bruce 1988) , Sardinella albella ( Printrakoon & Purivirojkul 2011) Sardinella gibbosa ( Trilles et al. 2013) , Selaroides leptolepis and Carangoides malabaricus ( Rameshkumar et al. 2014) .