Nerocila exocoeti Pillai 1954
Creators: name: Trilles, Jean-Paul
name: Rameshkumar, Ganapathy
name: Ravichandran, Samuthirapandian
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Cymothoidae
Nerocila
Nerocila exocoeti

description: Nerocila exocoeti Pillai 1954.
Synonymy: Nerocila exocoeti Pillai 1954: 12–13.— Kurochkin 1980: 289.—Bruce, 1987: 404.— Bruce and Harrison-Nelson 1988: 592–593.— Bruce and Bowman 1989: 1.— Trilles 1994: 89.— Kensley 2001: 233.— Sivasubramanian et al. 2011: 99–101.
Material examined: 10 female specimens [eight ovigerous, size from 25 to 28 mm, No. MNHN-IU-2009-1936, MNHN-IU-2009-1937 (Neotype) and AUCR 500 to 505; two non-ovigerous, size from 22 to 23 mm, No. AUCR 506 and 507], Parangipettai, Southeastern coast of India, on Exocoetus volitans, 12 April 2011.
Description of the ovigerous female (Figs. 7a–i, 8a–m, and 9a–e): Body about 2.5–2.8 as long as wide, widest between pereonite 5–6; cephalon anterior margin rounded; eyes with facets almost indistinct; Pereonites 1 and 5–7 longest, 2–4 subequal; pereonite 7 sometimes slightly shortest; posterior angles of pereonites 1–6 not produced; posterolateral angles of pereonite 7 produced backward into a pointed process; Coxae 2–4, often visible in dorsal view, produced into rounded processes, not exceeding beyond posterior of pereonites; Coxae 5–7, much more long than the anterior, posterior margin acute, reaching or extending slightly or distinctly beyond posterior of pereonites; All pleonites visibles, pleonite 1 shortest, pleonite 5 longest and widest, pleonies 2–4 subequal; Ventrolateral margins of pleonites 1–2 posteriorly directed and acute, extending to pleonites 3–4 or beyond pleonite 5, respectively; pleonites 3–5 lateral margins weakly acute; pleotelson 0.75–0.9 as long as wide, lateral margins convex, converging to indistinct apical point.
Antennula distinctly thicker than antenna, 8 articled, articles 5–8 each with posterodistal cluster of esthetes; antenna, 10 articled, 7–10 with setae. Mandible palp article 1 largest and article 3 without setae on distolateral margin; maxillula with three terminal spines; maxilla with two spines on medial lobe and one spine on lateral lobe; maxilliped with oostegial lobe, distal palp segment with three terminal spines. All pereopods without marginal spines, dactylus longer than propodus; pleopods 1–2 with all rami lamellar, three or four couplings hooks on protopod medial margin of pleopod 1 only, endopod proximomedial lobe well-developed but not folded; pleopod 2 with appendix masculina about 0.5 length of endopod; pleopods 3–4 endopod with a single or double lobe, proximomedial lobe well-developed and folded; pleopod 5 endopod with several large folds and proximomedial lobe well-developed and folded. Uropod slender, tapering and sublinear exopod and endopod, exopod about two times longer than endopod; endopod reaching or extending scarcely beyond the posterior margin of pleotelson; exopod extending by far beyond it.
As already reported by Pillai (1954), the entire body of the specimens was steel blue in color, with many chromatophores.
Host–parasite relationships
One hundred and sixty-four parasitic isopods belonging to 11 cymothoid species (Table 1, Figs. 2a–k) were collected. Among them, N. arres, N. depressa, and N. loveni are recorded for the first time from India. These 11 species were collected from 144 fish hosts belonging to 22 species and 15 families: Carangidae, Leiognathidae, Nemipteridae, Sciaenidae, Scombridae, Siganidae, Sphyraenidae, Terapontidae and Trichiuridae (Perciformes), Chirocentridae, Engraulidae, Pristigasteridae and Clupeidae (Clupeiformes), Ariidae (Siluriformes), and Exocoetidae (Beloniformes) (Table 1). Carangidae and Clupeidae are the most parasitized with three and five species, respectively.
N. arres, N. loveni, N. serra, and N. sundaica were widely distributed in the Nagappattinam. N. poruvae and N. longispina showed an extensive Vedaranyam distribution. N. loveni and N. depressa occurred only in Pazhaiyar region and N. sigani along the Mudasalodai coast. N. exocoeti, N. phaiopleura, and N. trichiura, appeared to be limited to the Parangipettai coast (Table 1).
From April 2009 to December 2011, the overall prevalence reached 8.74 %. A maximum prevalence was observed in N. depressa parasitizing Sardinella gibbosa (P = 12.5 %) and a minimum prevalence in N. sundaica parasitizing Ilisha melastoma (P = 3.84)%. The mean intensity ranged from 1 to 1.4 (Table 1).
For some species, the host-isopod association was not very specific. N. phaiopleura was collected from 13 host species belonging to seven families and 11 genera.and N. sundaica from six host species belonging to five families and six genera. These two species show a euryxenic parasitic specificity. While N. exocoeti and N. trichiura, only collected from the flying fish E. volitans, and N. sigani, only collected on the rabbit fish Siganus oramin, show an oïoxenic parasitic specificity. Carangoides malabaricus, E. volitans, Leiognathus splendens, Otolithes ruber, Sardinella gibbosa, Selaroides leptolepis, Terapon puta, and Thryssa mystax were parasitized by at least two species of Nerocila. Fifteen new hosts were identified, seven for N. phaiopleura, four for N. sundaica, and one for N. depressa, N. exocoeti, N. loveni, and N. serra (Table 1).
Four species, N. arres, N. loveni, N. serra, and N. sigani, were attached on the caudal peduncle or on the caudal fin of the fishes. N. depressa, N. exocoeti, N. longispina, N. phaeopleura, N. poruvae, N. sundaica, and N. trichiura, were collected from the body surface, on the head, on the pectoral fin or from the caudal peduncle of hosts.
description: Published as part of Trilles, Jean-Paul, Rameshkumar, Ganapathy & Ravichandran, Samuthirapandian, 2013, Nerocila species (Crustacea, Isopoda, Cymothoidae) from Indian marine fishes, pp. 1273-1286 in Parasitology Research (1273) (1273) 112 (3) on pages 1279-1282, DOI: 10.1007/s00436-012-3263-5, http://zenodo.org/record/11376477