Lobothorax typus Bleeker, 1857

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 : 35

Lobothorax typus Bleeker, 1857

( Fig. 2 p–r)

Lobothorax typus Bleeker, 1857: 39–40 , fig. 16.— Stebbing, 1893: 35.— Nierstrasz, 1931: 130.— Yu & Bruce, 2006: 641–648, figs 1–3.— Rameshkumar, Ravichandran & Allayie, 2013b: 127–132, fig. 6 .—Rameshkumar, Ramesh, Ravichandran & Trilles, 2014c: 940–944, fig. 1e.—Anand Kumar, Rameshkumar, Ravichandran, Rethna Priya, Nagarajan & Kwang Leng, 2015: 206–210, fig. 2b.

Saophra typus .— Schiöedte & Meinert, 1883: 283, pl. 11 (figs 1, 2).

Saophra typus .— Nierstrasz, 1915: 87; Trilles, 1994: 114.

Type and type locality. Lobothorax typus Bleeker, 1857 ; by monotypy, collected from Jakarta , Java, Indonesia .

Material examined. 3 ovig. females (20–23 mm), Parangipettai , 15 February 2013, from Trichiurus lepturus Linnaeus, 1758 , coll. G. Rameshkumar ( CAS / MBRM C- 127– C- 129) , 1 ovig. female (23 mm) Nagappatinam , 30 May 2016, from Trichiurus lepturus Linnaeus, 1758 , coll. S. Ravichandran ( ZSI / MBRC D1-537) , 2 non ovig. females (19, 22 mm), Parangipettai , 05 March 2017, from Trichiurus lepturus , coll. P. Vigneshwaran ( CAS / MBRM C- 130– C- 131), all localities from the southeast coast of India .

Diagnosis and description. Yu & Bruce (2006) provided a detailed diagnosis and description of the Chinese water specimen. We include here illustrations and a brief diagnosis of the Indian female specimen only.

Body straight, about 2.5–3 times as long as maximum width, widest at pereonite 5. Pereon with longitudinal mediodorsal ridge. Cephalon triangular, anterior margin produced to form narrowly rounded rostrum, eyes of moderate size. Pereonite 1 longest, anterolateral processes expanded apically. Pereonites 5–7 conspicuously shorter than other pereonites and decreasing in width. Coxae all shorter than pereonites. All pleonites visible, subequal in length. Pleotelson long as wide, subrectangular, posterior margin tapering to caudomedial point. Pereopod 1 robust, basis rectangular; merus less than half length of ischium, inferior margin weakly dilated; pereopods 2 and 3 longer than pereopod 1. Pereopods 4–7 basis with posterior expansion becoming progressively larger toward posterior. Pereopods 5–7 carpus short, triangular. Pleopods all lamellar, all peduncles with developed lobes. Pleopods 3–5 endopods with 2 marked depressions. Brood pouch made up of 4 pairs of oostegites, arising from sternites 2, 3, 4, and 6.

Colour. Ivory white in ethanol. Other examined specimens are yellowish-brown and dark brown in ethanol.

Size. Ovig. females, 20–23 mm; non ovig. females, 19–22 mm.

Remark. Yu & Bruce (2006) redescribed and diagnosed Lobothorax typus from China. Lobothorax typus can be identified by the anterolateral margins of pereonite 1 projecting forward beyond the anterior margin of the cephalon, pereonites 1–7 each with an ill-defined longitudinal, dorsal median ridge, and pereonites 5–7 each abruptly shorter than pereonite 4; the flattened rostrum; and pereonites 5–7 being very short in comparison to Ceratothoa and Glossobius , which have only pereonite 7 shorter than pereonite 6. In addition, Lobothorax has a proximolateral lamella on all pleopod exopods (not present in Ceratothoa and Glossobius ). Glossobius may also be distinguished by the head not being immersed into, or laterally overlapped by, pereonite 1.

These specimens agree well with the description provided by Bleeker (1857) from Batavia (Jakarta). The second species added to this genus was Lobothorax aurita ( Schiöedte & Meinert, 1883) (then placed in the genus Saophra ). Richardson (1910) described the third species, Lobothorax laevis from the Philippines.

The extent to which variation in this species is either regional, host mediated or both is still not apparent, as indicated by variations in the specimens allocated to L. typus Yu & Bruce (2006) . The Indian specimen is most similar to the Chinese specimen. The Indian specimen has a shorter body, 1.7 times longer than wide (as opposed to 2.4 times longer than wide); more visible cephalon with anterolateral margins of pereonite 1 minute; pereopods 5–7 carpus short, triangular.

Distribution. This species widely distributed from the South-eastern Asia region: Jakarta, Java, Indonesia (as Batavia Bleeker 1857; Schiöedte & Meinert 1883), South China Sea ( Yu & Bruce 2006), East Malaysia (Anand Kumar et al. 2015) and southeastern coast of India ( Rameshkumar et al. 2013; 2014).

Hosts. The only known family Trichiuridae : Lepturacanthus savala (Cuvier, 1829) ( Yu & Bruce 2006) and Trichiurus lepturus ( Rameshkumar et al. 2013; 2014; Anand Kumar et al. 2015).

Figures

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 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.