Nerocila Leach, 1818

Aneesh, Panakkool-Thamban, Helna, Ammeri Kottarathil, Valarmathi, Kandasamy, Chandra, Kailash & Mitra, Santanu, 2017, Redescription of Nerocila exocoeti Pillai, 1954 (Crustacea: Isopoda: Cymothoidae) parasitic on beloniform (Exocoetidae and Hemiramphidae) hosts with Nerocila madrasensis Ramakrishna & Ramaniah, 1978 placed into synonymy, Zootaxa 4365 (3), pp. 385-394 : 386-387

Genus Nerocila Leach, 1818

Nerocila Leach, 1818: 351 .— Desmarest 1825: 307; Edwards 1840: 250; Dana 1853: 747; Schiodte & Meinert 1881: 4; Gerstaecker 1882: 231; Richardson 1905: 219; Hale 1926: 202; Monod 1931: 5; Van Name, 1936: 431; Barnard, 1936: 163; Brian & Dartevelle, 1949: 135; SZidat, 1955: 216; Kensley 1978: 82; Kussakin 1979: 275; Brusca 1981: 150; MenZies & KrucZynski 1983: 55; Brusca & Iverson 1985: 45; Bruce 1987: 355 –412; Yu & Li, 2002: 266 –269.

Ichthyophilus Latreille, 1802: 133 .

Emphylia Koelbel, 1879: 413–414.

Pterisopodus Boone, 1918: 596.

Nerocila (Emphylia) Miers, 1880: 4 .— Bowman 1978: 34.

Type species: Nerocila blainvillei Leach, 1818 (see Bruce 1987).

Neotype designation for Nerocila exocoeti Pillai, 1954 : Trilles et al. (2013) designated a neotype for Nerocila exocoeti Pillai, 1954 , though this action was not justified by the authors and thus did not meet the requirements of The Code Article 75.3 ( Anon 1999), and as such is not valid. The original description of Nerocila exocoeti Pillai, 1954 was accompanied by brief descriptions of the adult female. Pillai (1954) specified that the only distinguishing character of N. exocoeti , was the proportional size of the coxal plates, coxa 2 being small, not extending beyond the posterior border of the segment and the coxa 7 reaching the anterior margin of pleonite 1 and that the whole body was ‘steel blue’ in colour; males were not described. Although the description contains some species-specific details, the level of detail is inadequate by modern standards. Fortunately the type locality (Trivandrum, Kerala Coast) and the type host of N. exocoeti were clearly stated, namely Parexocoetus brachypterus (Richardson) (Exocoetidae) . Pillai (1954) stated that the holotype was deposited in Indian museum, Kolkata but they didn’t give a registration number. Enquiries at the Indian museum failed to reveal any material that could be definitely identified, or indeed even potentially considered as the type material for material for N. exocoeti . As there are no museum records of Pillai’s (1954) material it seems that, inevitably, the types were either not deposited or have been subsequently lost.

There are few subsequent records of this species; Bruce and Harrison-Nelson (1988), reported N. exocoeti from P. brachypterus and Scomberomorus multiradiatus (Scombridae) (may be as gut content) from Papua New Guinea, Indonesia, and from Taiwan. Sivasubramanian et al. (2011) published photographs of N. exocoeti from flying fish Exocoetus volitans (Exocoetidae) collected from the Parangipettai, southeastern coast of India without providing any description. The most recent account and redescription is that of Trilles et al. (2013).

The new material of Nerocila exocoeti Pillai, 1954 described here is from the type host Parexocoetus brachypterus (Exocoetidae) from Marina Beach, Chennai , India, 13.0500°N, 80.2824°E, Bay of Bengal. We uphold the Trilles et al. (2013) neotype designation (MNHN-IU-2009-1937) from Exocoetus volitans (Exocoetidae) collected from Parangipettai, South Eastern Coast of India coll. by Rameshkumar on 12 April 2011 and submitted in MNHN by J.P. Trilles. The Parangipettai, South Eastern Coast of India, is approximately 450 km away from Pillai's (1954) original type locality (Trivandrum, Kerala Coast). We consider the new type locality resulting from the neotype designation to be similar from the original type locality “as nearly as practicable from the original type locality” ( Anon 1999, ICZN, Art. 75.3.6).

The present Indian material agrees well with the description and figures given by Pillai (1954) —the proportional size of the coxal plates, coxa 2 not extending beyond the posterior border of the segment and coxae 7 reaching the anterior of pleonite 1, and that the entire dorsal surface of the body is steel blue in color. The present material is 28 mm in size. We are confident that the present material from Parangipettai, South Eastern Coast of India (MNHN-IU-2009-1937) from Exocoetus volitans Linnaeus (Exocoetidae) , submitted in MNHN by J.P. Trilles, coll. Rameshkumar on 12 April 2011 and Pillai’s material from Trivandrum, Kerala Coast is the same species, and we have taken the decision to designate a neotype in order to conserve Pillai’s (1954) name and concept of this species and the future use of this name.