Ceratothoa guttata (Richardson, 1910)

Hadfield, Kerry A., Bruce, Niel L. & Smit, Nico J., 2016, Redescription of poorly known species of Ceratothoa Dana, 1852 (Crustacea, Isopoda, Cymothoidae), based on original type material, ZooKeys 592, pp. 39-91 : 55-57

Taxon classification Animalia Isopoda Cymothoidae

Ceratothoa guttata (Richardson, 1910) Figure 7

Meinertia guttata Richardson, 1910: 20-21, fig. 19.

Codonophilus guttatus .- Nierstrasz 1931: 132.

Meinertia venusta Avdeev, 1978: 30-32, pl. 1.

Ceratothoa venusta .- Avdeev 1981: 1160-1167, fig. 3; 1990: 32-42, figs 1-6.- Trilles 1986: 625, tab. 1; 1994: 129-130.

Ceratothoa guttata .- Bruce and Bowman 1989: 4-7, figs 3-4.- Trilles 1994: 119-120.- Kensley 2001: 232.- Bruce, Lew Ton and Poore 2002: 172.- Martin, Bruce and Nowak 2015a: 271-272.

Material examined.

Lectotype [here designated]. United States National Museum, USA (USNM 1254762) - female (17 mm TL; 7 mm W), 7 Feb 1908, obtained off Jolo Island, Philippines; from a flying fish 4-5 inches long ( Richardson 1910). Specimen’s left side slightly damaged from pereonite 4 to 6. Paralectotypes. Five females (13.5-16 mm TL; 5-6 mm W), same data as lectotype (USNM 40914).

Description.

Lectotype female. Length 17 mm, width 7 mm.

Body oval and elongate, twice as long as greatest width, dorsal surfaces smooth and polished in appearance, widest at pereonite 5, most narrow at pereonite 1, lateral margins ovate. Cephalon 0.6 times longer than wide, visible from dorsal view, triangular. Frontal margin rounded to form blunt rostrum. Eyes irregular in outline. Antennula and antenna stout and same length. Antennula with 7 articles, antenna with 8 articles.

Pereonite 1 smooth, anterior border straight, anterolateral angle with small distinct anterior projection extending to base of eyes. Posterior margins of pereonites slightly produced medially. Coxae 2-3 wide, with posteroventral angles rounded; 4-7 large and produced on pereonite margins, not extending past pereonite margin. Pereonites 1-5 increasing in length and width; 6-7 decreasing in length and width; 2-5 subequal. Pleon with pleonite 1 most narrow, visible in dorsal view; pleonites posterior margin smooth, mostly concave. Pleonite 2 not overlapped by pereonite 7; posterolateral angles of pleonite 2 forming acute point. Pleonites 3-5 similar in form to pleonite 2; pleonite 5 free, not overlapped by lateral margins of pleonite 4, posterior margin produced medially. Pleotelson 0.6 times as long as anterior width, dorsal surface smooth, lateral margins weakly convex, posterior margin shallowly emarginate.

Pereopod 1 basis 1.5 times as long as greatest width; ischium 0.8 times as long as basis; merus proximal margin with large bulbous protrusion; carpus with straight proximal margin; propodus as long as wide; dactylus slender, 1.4 times as long as propodus, 2.4 times as long as basal width. Pereopod 7 basis 0.8 times as long as greatest width; ischium 1.3 times as long as basis, with a large proximal bulbous protrusion overlapping merus; merus proximal margin with large distal bulbous protrusion, merus 0.7 times as long as wide, 0.3 times as long as ischium; carpus 0.7 times as long as wide, 0.3 times as long as ischium, without bulbous protrusion; propodus 1.4 times as long as wide, 0.5 times as long as ischium; dactylus slender, 1.4 times as long as propodus, 2.6 times as long as basal width.

Uropod more than half the length of pleotelson, peduncle 0.8 times longer than rami.

Other material

. Holotype of Ceratothoa venusta . Russian Pacific Federal Fisheries Research Institute (AGK 75054) - on flying fish, Parexocoetus brachypterus , from the Red Sea ( Avdeev 1978).

Size.

Ovigerous females: 14.5-23.0 mm TL; non-ovigerous females: 15.5-16.5 mm TL; males: 5.4-7.4 mm TL ( Bruce and Bowman 1989).

Distribution.

Central and Western Indo-Pacific: Philippines ( Richardson 1910, Nierstrasz 1931, Bruce and Bowman 1989, Kensley 2001); Red Sea ( Avdeev 1978, Bruce and Bowman 1989, Kensley 2001); Madagascar; Australia; and Taiwan ( Bruce and Bowman 1989, Kensley 2001).

Hosts.

In mouths of flying fish, Parexocoetus brachypterus (see Bruce and Bowman 1989, Avdeev 1978).

Remarks.

Ceratothoa guttata is distinguished by the elongate body widest at pereonite 5; uropods which do not extend past the posterior margin of the pleotelson; a narrow pleon; an expanded merus on pereopod 1; and an expanded ischium and merus on pereopod 7.

Ceratothoa guttata is considered to be highly host specific as it has, to date, only been reported from a single host, Parexocoetus brachypterus . Avdeev (1978) briefly described Meinertia venusta from the Red Sea on Parexocoetus brachypterus , comparing it to Ceratothoa guttata . Bruce and Bowman (1989) revised Ceratothoa guttata and synonymised Ceratothoa venusta with Ceratothoa guttata after comparing drawings of the two species. Similar morphology of pereopods 1 and 7, coxae, the pleon and the pereon, as well as the host specificity all confirm this synonymy. The largest female is here redescribed and reillustrated and designated as lectotype.