Pedinura, Bruce, 2003

Bruce, N. L., 2003, New genera and species of sphaeromatid isopod crustaceans from Australian marine coastal waters, Memoirs of Museum Victoria 60 (2), pp. 309-369 : 355-356

Pedinura gen. nov.

Type species. Pedinura flindersia sp. nov., here designated.

Diagnosis. Pleotelson posterior margin entire, posteriorly produced, without exit channel, without ventral depression or groove. Antennule and antenna anteriorly positioned, peduncle articles 1 and 2 flattened and expanded; antennule peduncle articles 2 and 3 short, less than half as long as article 1; article 3 and flagellum collinear. Pereopods 1, 4–7 robust, pereopods 2 and 3 slender, pereopods 2 and 3 dactylus with prominent comb seta set against unguis. Pleopods 1–3 with rami of about equal length; pleopod 1 with axis of rami straight, not oblique. Pleopod 2 appendix masculina medially inserted, extending beyond distal margin of endopod. Pleopods 4 and 5 endopod and exopod with thickened ridges. Uropods ventrolateral in position, not visible in dorsal view; exopod minute, inserted into lateral margin, stub-like.

Description of male. Body elongate, 3 times as long as greatest width, moderately vaulted; dorsal surface smooth; lateral margins subparallel; unable to conglobate. Head weakly immersed in pereonite 1; rostral process minute or absent. Eyes small, lateral. Pereon segments without raised posterior margins. Coxal plates fused, without discernable suture, overlapping anterior over posterior. Membrana cingula absent. Pleon with 4 segments, pleonite 1 entire, 2 lateral sutures running to posteri- or margin of pleon. Pleotelson posterior margin produced as plate-like extension posterior to pleopod chamber; without foramen, without ventral exit channel or groove. Pleonal sternite present.

Antennule and antenna anteriorly positioned. Antennule peduncles not separated by epistome; peduncle articles 1 and 2 expanded, anteriorly flattened; plane of articles 1 and 2 of projecting ventrally; peduncle articles 2 and 3 short, article 3 shorter than article 2, together about 0.5–0.8 as long as article 1; flagellum of 4 articles, slightly shorter than combined lengths of articles 1 and 2. Antenna slender, peduncle articles 1 and 2 short, appearing fused, peduncle articles 4 longer than articles 3 and 5; flagellum as long as or slightly longer than peduncle.

Epistome wide, unornamented. Labrum unornamented. Mandible incisor 3- or 4-cuspid; left mandible with lacinia mobilis or without; molar process with or without marginal serrations; palp article 1 longest, 3 shortest. Maxillule with lateral lobe with 11 RS on gnathal surface, mesial lobe with 2 long and 1 short CP slender setae and 2 short simple seta (type species). Maxilla with all articles well developed; lateral and middle lobes with flat RS, mesial lobe with blunt and acute long RS, some of which are basally CP. Maxilliped endite distally with cactus and club setae, laterally with 1 long curved CP seta; palp articles not mesially produced, mesial margins with numerous setae, lateral margins without setae.

Pereopods 1, 5–7 robust, 2 and 3 slender; pereopods 2 and 3 dactylus with prominent pectinate secondary unguis opposing unguis, all other pereopods with prominent recurved trifid secondary unguI.

Penes short, not extending to pleopod peduncles; mutually adjacent or slightly set apart.

Pleopods 1 with axis of both rami straight, not oblique, about equal in length. Pleopod 1 not operculate, not indurate. Pleopod 2 appendix masculina medially attached. Pleopods 3 exopod with transverse suture, pleopods 4 with or without suture, pleopod 5 without. Pleopods 4 and 5 exopod and endopods with transverse thickened ridges; pleopod 5 endopod with 2 or 3 distal scale patches. Uropods endopod lamellar, exopod minute, stub-like, set into anterolateral margin of endopod.

Female. Antennule peduncle of type species articles 1 and 2 greatly expanded anteriorly. Brood pouch of overlapping oostegites arising on pereonites 2, 3 and 4. Mouthparts not metamorphosed.

Composition and distribution. Pedinura flindersia sp. nov.; Pedinura mokari sp. nov.; subtropical WA to Vic., Australia.

Etymology: A combination of Greek pedinos (flat, even), and oura (tail), alluding to the flattened pleotelson of the two species (feminine).

Remarks. The characters that best distinguish Pedinura are: the plate-like extension to the posterior margin of the pleotelson entirely lacking any exit channel, groove or depression; ventral uropods (not visible in dorsal view) with a minute exopod; expanded articles to antennule peduncle articles 1 and 2; and the appendix masculina being mesially inserted and extending beyond the distal margin of the exopod.

Pedinura resembles Amphoroidea Milne Edwards, 1840 , A. angustata Baker, 1908 being the most similar. Although Amphoroidea and its species have not been fully described, the two genera can immediately be separated by Amphoroidea having anterolateral uropods, prominent in dorsal view and extending well beyond the posteriorly narrowed pleotelson. Further points of distinction include the appendix masculina being basal (mesial in Pedinura ), pleopod 1 endopod distinctly triangular with an indurate mesial margin, and the uropod with both rami large and lamellar.

Cassidinopsis Milne Edwards, 1840 is similar ( Brandt, 1998) but in that genus the antennule peduncular articles 1 and 2 are not expanded, pereopod 2 lacks the pectinate robust seta opposite the dactylus, and most notably the uropods are lateral (not ventral) and extend well to the posterior of the pleotelson which is not posteriorly produced.