Pleopodias vigilans Richardson, 1911

Hadfield, Kerry A. & Smit, Nico J., 2017, Revision of the fish parasitic genus Pleopodias Richardson, 1910 (Isopoda, Cymothoidae), with the description of a new species and key to the genus, ZooKeys 667, pp. 21-37 : 25-26

Pleopodias vigilans Richardson, 1911

Pleopodias vigilans Richardson, 1911: 525-526.

Material examined.

Holotype. Female (28 mm TL, 11 mm W), 9 July 1883, collected from the Talisman, St. DR71 (dredge), 640 m depth, coast of Sudan, MNHN-IU-2014-12188 (= MNHN-Is2460). Also noted: the specimen is black with the pleotelson folded in.

Description.

Female holotype. Length 28 mm, width 11 mm.

Body elongate, 2.9 times as long as greatest width, dorsal surfaces slightly bumpy, widest at pereonite 4, most narrow at pereonite 1. Cephalon 0.6 times longer than wide, visible from dorsal view, subtriangular. Frontal margin thickened, ventrally folded and truncate. Eyes not clearly defined; one eye 0.4 times width of cephalon, 0.6 times length of cephalon. Pereonite 1 smooth, anterior border slightly irregular, anterolateral angle narrowly rounded. Posterior margins of pereonites smooth and straight. Coxae 2-3 wide, with posteroventral angles rounded; 4-7 small and narrow, extending past pereonite margin. Pereonites 1-4 increasing in length and width; 5-7 decreasing in length and width. Pleonites posterior margin not smooth, mostly concave. Pleonite 1 widest, slightly visible in dorsal view. Pleonite 2 not overlapped by pereonite 7; posterolateral angles of pleonite 2 rounded. Pleonites 3-5 progressively getting smaller; pleonite 5 with posterolateral angles rounded, posterior margin produced medially. Pleotelson 1.2 times as long as anterior width, dorsal surface slightly depressed, lateral margins posteriorly narrow, posterior margin converging to rounded caudomedial point.

Antennula thinner and shorter than antenna, bases widely separated, consisting of 8 articles; peduncle articles 1 and 2 distinct and articulated; extending past the posterior margin of cephalon. Antenna consisting of 11 articles, extending to posterior of pereonite 2. Pereopod 1 basis 1.6 times as long as greatest width; ischium 0.7 times as long as basis; merus proximal margin without bulbous protrusion; carpus with straight proximal margin; propodus 1.5 times as long as wide; dactylus slender, 1.8 times as long as propodus. Pereopod 7 longer than other pereopods, basis 2.4 times as long as greatest width; ischium 0.6 times as long as basis, without protrusions; merus proximal margin without bulbous protrusion, 1.3 times as long as wide, 0.6 times as long as ischium; carpus 1.1 times as long as wide, 0.4 times as long as ischium, without bulbous protrusion; propodus 2.3 times as long as wide, 0.9 times as long as ischium; dactylus slender, 1.1 times as long as propodus, 3.7 times as long as basal width. Uropod longer than the pleotelson; peduncle 0.4 times longer than rami, peduncle lateral margin without setae, apices broadly rounded. Endopod apically rounded, 3.5 times as long as greatest width. Exopod extending beyond posterior of endopod, 5 times as long as greatest width, apically rounded.

Distribution.

Sudan ( Richardson 1911).

Hosts.

Not known.

Remarks.

Pleopodias vigilans can be identified by the antennula bases being widely separated, large eyes occupying majority of the cephalon, antenna extending to posterior of pereonite 2, uropodal exopod longer than endopod, and rounded pleotelson with a caudomedial point.

Only one specimen of this species has ever been collected. Due to the age and condition of the specimen, it was not possible to see some of the characters usually associated with Pleopodias (i.e. robust setae on pereopod 7 etc.).

No figures of the specimen were provided in the original description, and as no other collections have been made since, no drawings of the specimen have ever been produced. This redescription provides the first illustrated figures of P. vigilans and will help future identifications of this species. Fresh collections of this species could prove valuable in adding to this information, along with information on the mouthparts and pleopods of this species.