Mothocya collettei Bruce, 1986

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 : 36-38

Mothocya collettei Bruce, 1986

( Fig. 3 a–c)

Mothocya collettei Bruce, 1986: 1145–1149 , figs 31–33.— Hadfield, Bruce & Smit, 2015: 161.— Aneesh, Helna & Sudha, 2016: 1270–1277, fig. 2h, i.— Nagasawa, 2017: 613–616, fig. 1.

Types and locality. Holotype, held at The Queensland Museum, Brisbane, Queensland, Australia ( QM W11728), refer to Singapore, Straits of Malacca .

Material examined. 2 ovig. females (25, 27 mm), Parangipettai , 04 January 2017, from Strongylura strongylura , coll. P. Vigneshwaran ( CAS / MBRM C- 149– C- 150) .

Remarks. This species is recognised by the scarcely twisted body, a long, very wide pleotelson, pleon with subparallel sides (in contrast to M. plagulophora where pleonite 5 is widest), relatively straight body shape, wide rounded posterior coxal plates, and uropods that are relatively short with a slender endopod. Another character which will separate this species from nearly all others is the presence of a prominent lateral peduncular lobe on pleopod 1.

Mothocya affinis Hadfield et al. 2015 is similar to M. collettei Bruce, 1986 but is smaller in size (average 15.7 mm compared with 20.5 mm in M. collettei), has a different host, has a more twisted and convex body shape, has one recurved seta on the medial maxilla lobe (vs two in M. collettei), three recurved setae on maxilliped article 3 (four in M. collettei), the shape of the coxae is less wide and longer laterally than M. collettei, shorter uropods, and the pleotelson is not as wide and round as M. collettei. Mothocya karobran is the most similar species: other characters are discussed under Remarks for M. karobran to which this species is similar.

Bruce (1986) found considerable variations in several characters and measurements between specimens from the central Pacific (Hawaii, Tubuai Island and Tahiti) and the West Pacific and the Indian Ocean. The present specimen is much bigger than females (25, 27 mm) from the West Pacific and the Indian Ocean but is close to the largest female (26.0 mm) from the central Pacific. The posterior margin of the pleotelson of the specimen has a slightly narrowed, which is similar to that of a Tubuai specimen ( Bruce 1986, fig. 33a), while that of a typical individual of the species is widely rounded ( Bruce 1986, fig. 31a). Bruce (1986) also suggested that specimens from the central Pacific (Tubuai Island and Tahiti) and Magnetic Island, Australia, have extremely wide coxae and may be a distinct species from M. collettei . It is thus desirable to study morphological and size variations of specimens from the above localities and India in order to clarify whether they are distinguished from M. collettei .

Colour. Pale tan to dark reddish brown in alcohol. Scattered chromatophores present ( Bruce 1986).

Size. Ovig. females 13–27 mm; non ovig. females 13–26 mm; males 10–16.5 mm ( Bruce 1986).

Distribution. Recorded from the Kenya, Singapore, Thailand, north-eastern Australia, Papua New Guinea, Philippines, Yap Is. in the Caroline Islands, Tubuai Is. in the Austral Group, Tahiti, Hawaii ( Bruce 1986), India ( Aneesh et al. 2016) and Japan ( Nagasawa 2017).

Host. Mothocya collettei were only recorded from the family Belonidae : Strongylura strongylura (van Hasselt, 1823) (Present study), Tylosurus crocodilus (Péron & Lesueur, 1821) ( Bruce 1986; Aneesh et al. 2016; Nagasawa 2017).

Figures

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).