Pleopodias Richardson, 1910

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 : 22

Genus Pleopodias Richardson, 1910

Pleopodias Richardson, 1910: 25-26.-Barnard, 1936: 166-167.-Bruce, 1987: 87.-Trilles, 1994: 109.

Type species.

Pleopodias elongatus Richardson, 1910, by monotypy.

Diagnosis.

Body elongate; cephalon slightly immersed in pereonite 1, posterior margin not trilobed; eyes large and distinct. Rostrum folded back, lying between antennula bases, not concealing basal articles. Antennula long and narrow, extending past cephalon posterior margins; antenna longer than antennula, extending to or beyond pereonite 2, articles 3-6 elongate. Pereon most narrow at pereonite 1; pleon narrower than pereon with pleonites progressively getting narrower from pleonite 1 to 5; pleotelson elongate, 1.2-1.8 times longer than wide. Pereonite 2 shortest in length, pereonite 6 longest. Uropods long and narrow, extending beyond the posterior margin of the pleotelson. Pereopod 7 longer than other pereopods with the merus, carpus and propodus on pereonite 7 elongated.

Remarks.

Pleopodias can be identified by the long antennae, with the antennula shorter than the antenna; body most narrow at pereonite 1; narrow pleon with the width of the pleonites decreasing from pereonite 1 to 5; pereopod 7 longer and more elongate than other pereopods; uropods extending past the posterior margin of the pleotelson; and a longer than wide pleotelson.

The original diagnosis for this genus was provided by Richardson (1910) but was based on the only species known at that time, P. elongatus . In his report on a Pleopodias sp. from the Andaman Islands, Barnard (1936) pointed out that of some of the generic characters used by Richardson to define the genus (i.e. antennula articles 2 and 3 expanded, and pleopods visible in dorsal view) were shared with Anilocra Leach, 1818 and thus not very informative. Bruce (1987) revised both Pleopodias and Anilocra simultaneously and was able to provide a number of differences between the two genera. According to Bruce (1987), Pleopodias has a narrow pleon, getting strongly narrower towards the posterior (not always narrower in Anilocra ); antennula articles 4-8 are elongate (not in Anilocra ); large robust setae on the maxilla and the medial lobe is distinct (acute, simple robust setae and the maxilla is partially fused in Anilocra ); article 3 of the mandible palp is slim and longer than article 2 (article is stout and short in Anilocra ); and pereopod 7 with more robust setae than observed in Anilocra . Bruce (1987) also included mouthpart and pleopod morphology in the generic diagnosis of Pleopodias , however, as not all species have these characters noted, we have refrained from adding them into the currently revised diagnosis.

Key to the species of the genus Pleopodias

This key is based on the morphological characters of the gravid female: