Styloptocuma spinosum, 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 : 168-169

Styloptocuma spinosum sp. nov.

Figures 62 , 63

Material examined. Holotype female, NSW, off Nowra, 34°57.90'S, 151°08'E, 503 m, bryozoa and shell, WHOI epibenthic sled, G.C.B. Poore et al., RV Franklin, 14 Jul 1986 (stn SLOPE 2 ), NMV J53018.

Paratype: 1 female (stn SLOPE 2 ), NMV J53019 .

Diagnosis. Carapace with middorsal row of spines, another lateral and lower margin densely serrated. Dorsal serrated crest on pleonites 1–5. Pereopod 1 with propodus 2nd longest article. Pereopod 2 with dactylus 3 times as long as propodus. Last 3 pairs of pereopods slender. Uropod peduncle serrated on inner margin, twice as long as pleonite 6 and 1.5 times as long as its equal rami.

Description. Body elongate, with weakly calcified integument. Length: 2.36 mm.

Carapace 3rd of body length, 1.7 times as long as high, pseudorostrum quarter of carapace length, slightly upturned, siphon longer than carapace, a middorsal row of spines, 1 bigger spine on ocular lobe, ocular lobe eyeless, reaching extremity of pseudorostral lobes, a median row of spines near lower serrated margin, scattered setae. Pereon glabrous. Pleon elongate, 0.58 of body length, with dorsal serrated crest on pleonites 1–5, without setae.

Antenna 1 basal article of peduncle 2.5 times as long as rest of articles combined, median article longer than distal one, without visible tubercle, main flagellum longer than last article of peduncle, accessory flagellum minute.

Maxilliped 3 basis half of appendage, with 2 plumose setae on outer margin, merus and carpus with plumose seta on outer distal corner, propodus 2nd longest article, twice as long as dactylus.

Pereopod 1 basis shorter than rest of articles combined, ischium with small tooth on inner margin, merus twice as long as ischium, carpus 4 times merus and dactylus combined, propodus 2nd longest article, twice as long as carpus, dactylus with slender terminal long seta. Pereopod 2 basis one-third of appendage length, simple seta on distal inner corner of basis and merus, carpus twice as long as merus, with 2 unequal stout setae on inner distal corner, dactylus 3 times as long as propodus, with simple setae. Pereopods 3–5 slender, basis longer than rest of articles combined in 3rd pair, progressively shorter in pairs 4 and 5, carpus progressively longer in pairs 3–5, carpus 5 times as long as merus in 5th pair. Exopods on maxilliped 3 and pereopods 1, 2.

Uropod peduncle serrated on inner margin, twice as long as pleonite 6 and 1.5 times as long as its equal rami, exopod with few fine setae on outer margin and a stout terminal seta, endopod with 3 setae on inner margin and a terminal seta longer and more robust than in exopod.

Etymology. The name of the species reflects the numerous spines of carapace.

Distribution. Off Nowra, NSW; 503 m depth.

Remarks. Some features of the carapace, about 20 dorsal spines, a lateral row of spines near the lower densely serrated margin combined with dorsal serration of the pleon, make Styloptocuma spinosum unique within Australian species of the genus. Such carapace armature may also be found in S. antipai Băcescu and Muradian, 1974 from the deep western Atlantic and S. echinatum Jones, 1984 from the eastern Atlantic. The new species differ in the glabrous pereon, absence of lateral rows of spinules on the pleon and the shorter carpus of pereopod 2.

Figures

Figure 62. Styloptocuma spinosum sp. nov. female holotype: a, body, lateral view; b, carapace, lateral view, magnified; c, antenna 1; d, maxilliped 3. Scale (in mm): a, 0.5; b, c, 0.5; d, 0.25.

Figure 63. Styloptocuma spinosum sp. nov. female holotype: a, pereopod 1; b, pereopod 2; c, pereopod 3; d, pereopod 4; e, pereopod 5; f, pleonite 6 and right uropod. Scale (in mm): a–e, 0.25; f, 0.5.