Styloptocuma australiense, Petrescu, 2006

Petrescu, Iorgu, 2006, Nannastacidae (Crustacea: Cumacea) from eastern Bass Strait, the south-eastern Australian slope, and Antarctica in the collections of Museum Victoria, Memoirs of Museum Victoria 63 (2), pp. 129-173 : 163-164

Styloptocuma australiense sp. nov.

Figures 53 , 54

Material examined. Holotype female, NSW, off Nowra, 34°51.90'S, 151°12.60'E, 770 m, crinoid dominated, WHOI epibenthic sled, G.C.B. Poore and C.C. Lu, RV Franklin, 15 Jul 1986 (stn SLOPE 6 ), NMV J53062.

Paratype: 1 female (stn SLOPE 6 ), NMV J53063 .

Diagnosis. Carapace short, with long pseudorostrum, lower margin smooth. Integument with few setae on carapace, smooth on rest of body. Pereopod 1 with carpus as long as propodus. Dactylus of pereopod 2 twice as long as propodus. Uropod peduncle 2.8 times as long as pleonite 6, with serrated inner margin 1.3 times as long as endopod, exopod shorter than endopod, endopod with 4 setae on inner margin and robust curved terminal seta.

Description. Body elongate, integument carapace covered with sparse setae. Length: 3.2 mm.

Carapace shorter than one-third body length, 1.7 times as long as high, long pseudorostrum (0.4 of entire carapace length), antennal notch absent, lower margin smooth, ocular lobe eyeless, reaching extremity of pseudorostral lobes, conical in dorsal view. Pleon 0.55 body length.

Antenna 1 peduncle with progressively shorter articles, median article with tubercle with 2 sensory setae, main flagellum 3-articulate, longer than distal article of peduncle, median and distal article with 1 aesthetasc, accessory flagellum minute, uniarticulate.

Maxilliped 3 basis shorter than rest of articles combined, with 2 plumose setae on inner margin and 4 (2 long, 2 short) plumose setae on outer distal corner, short ischium, merus shorter than carpus, merus and carpus with long plumose seta on outer margin, propodus 2nd longest article, with 2 pappose setae on inner margin, dactylus longer than merus, with 2 stout curved terminal setae.

Pereopod 1 basis less than half as long as appendage, ischium shorter than merus, carpus longer than merus, as long as propodus, dactylus 0.4 propodus length, with long simple stout terminal seta. Pereopod 2 less than half as long as appendage, merus with seta on inner margin, carpus almost twice as long as merus, with 1 seta on inner margin and 2 on outer margin, 2 stout setae on distal inner corner, dactylus twice as long as propodus, with simple setae. Pereopods 3–5 with progressively shorter basis and longer carpus (twice as long as merus in 5th pair), propodus longer than merus, dactylus with a long stout terminal seta. Exopods on maxilliped 3 and pereopods 1, 2.

Uropod peduncle 2.8 times as long as pleonite 6, with serrated inner margin, 1.3 times as long as endopod, exopod shorter than endopod, with a stout terminal seta, endopod with 4 setae on inner margin and robust curved terminal seta.

Etymology. The species bears the name of type locality – Australia.

Distribution. Off Nowra, NSW; 770 m depth.

Remarks. This is the first record of the genus Styloptocuma from Australian waters. It was previously known from the deep Atlantic ( Băcescu, 1992) and Eastern Pacific ( Petrescu, 1991; Petrescu and Watling, 1999). Styloptocuma australiense is morphologically similar to S. angustatum Jones, 1984 from the Western Atlantic ( Brazil): both have a carapace without spines or tubercles, a similar anterolateral margin and almost similar pereopods 1 and 2. The new species differs in having a longer pseudorostrum, shorter carapace, and uropod endopod with four setae on the inner margin instead of three.

Figures

Figure 53. Styloptocuma australiense sp. nov. female holotype: a, body, lateral view; b, carapace, dorsal view; c, antenna 1; d, maxilliped 3. Scale (in mm): a, b, 0.5; c, 0.1; d, 0.2.

Figure 54. Styloptocuma australiense sp. nov. female holotype: a, pereopod 1; b, pereopod 2; c, pereopod 3; d, pereopod 4; e, pereopod 5; f, pleonite 6 and left uropod. Scale (in mm): a–e, 0.25; f, 0.5.