Ceratothoa gobii Schioedte & Meinert, 1883

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 : 53-55

Taxon classification Animalia Isopoda Cymothoidae

Ceratothoa gobii Schioedte & Meinert, 1883 Figure 6

Ceratothoa Gobii Schioedte & Meinert, 1883: 356-358, tab. XV (Cym. XXII) figs 12-13.

Ceratothoa gobii .- Carus 1885: 443.- Trilles 1994: 119.- Horton 2000: 1042-1043.

Meinertia gobii .- Montalenti 1948: 36.

Material examined.

Holotype. Museum of Comparative Zoology, USA (MCZ 3707) - female (12 mm TL; 5 mm W), from the sand goby, Gobius minutus , from Messina, Italy, coll. Haeckel. Specimen with broken antennae and damaged pereonite 2.

Description.

Holotype female. Length 12 mm, width 5 mm.

Body elongate, 1.9 times as long as greatest width, dorsal surfaces smooth and polished in appearance, widest at pereonite 5, most narrow at pereonite 1, lateral margins slightly convex. Cephalon 0.7 times longer than wide, visible from dorsal view, triangular. Frontal margin rounded to form blunt rostrum. Eyes oval with distinct margins, one eye 0.3 times width of cephalon; 0.6 times length of cephalon.

Pereonite 1 smooth, anterior border straight, anterolateral angle with small distinct produced point and produced past frontal margin of cephalon, extend to middle of the eye. Posterior margins of pereonites smooth and straight. With posteroventral angles rounded; coxae 4-7 rounded; not extending past pereonite margin. Pereonites 1-5 increasing in length and width; 6-7 decreasing in length and width; becoming more progressively rounded posteriorly. 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 narrowly rounded. 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 0.4 times as long as anterior width, dorsal surface smooth, lateral margins weakly convex, posterior margin subtruncate and shallowly emarginate.

Pereopod 1 basis 1.4 times as long as greatest width; ischium 0.7 times as long as basis; merus proximal margin with bulbous protrusion; carpus with rounded proximal margin; propodus 1.7 times as long as wide; dactylus slender, as long as propodus, 3 times as long as basal width. Pereopod 7 basis as long as greatest width; ischium 0.8 times as long as basis, without protrusions; merus proximal margin with large bulbous protrusion, merus 0.4 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, with slight bulbous protrusion; propodus 1.1 times as long as wide, 0.4 times as long as ischium; dactylus slender, 1.6 times as long as propodus, 2.7 times as long as basal width.

Uropod same length or slightly longer than the pleotelson, peduncle 0.6 times longer than rami, peduncle lateral margin without setae; rami extending beyond pleotelson, marginal setae absent, apices narrowly rounded. Exopod extending to end of endopod.

Remarks.

Ceratothoa gobii has a triangular cephalon with a sub-truncate rostrum; large eyes which together take up more than half of the cephalon; uropods which extend past the posterior margin of the pleotelson; short anterolateral projections on pereonite 1; and pleonites 1-5 gradually becoming wider.

This species is based on the description of a single specimen by Schioedte and Meinert (1883) without mention of a type host; however, Gobius minutus (now Pomatoschistus minutus ) is listed on the information in the museum bottle. This species has only been collected once.