Styloptocuma nodosum, 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 : 165-167

Styloptocuma nodosum sp. nov.

Figures 57–60

Material examined. Holotype female, Vic., S of Point Hicks , 38°25'S, 149°00'E, 1500 m, compacted clay, WHOI epibenthic sled, G.C.B. Poore et al., RV Franklin, 22 Jul 1986 (stn SLOPE 27 ), NMV J53064.

Allotype: male (stn SLOPE 27 ), NMV J53065.

Paratypes: 3 females, 1 immature male, 7 mancas, 1 adult male, dissected (stn SLOPE 27 ), NMV J53066 .

Diagnosis. Carapace with short pseudorostrum, without antennal notch, slightly serrated lower margin. Antenna 1 with tooth on distal article of peduncle. Carpus and propodus of pereopod 1 subequal. Carpus of pereopod 2 3 times as long as merus, dactylus with subterminal long seta. Uropod peduncle 2.9 times as long as pleonite 6 and 1.3 times as long as its equal rami.

Description of female. Body with few hairs on carapace. Length: 4.7 mm.

Carapace third of body length, 1.6 times as long as high, with short upturned pseudorostrum (0.3 of carapace length), with knotty surface and few long setae, antennal notch absent, lower margin slightly serrated, ocular lobe eyeless. Pleon more than half body length.

Antenna 1 slender, basal article of peduncle much longer than rest of articles combined, median article with minute tubercle, distal one with strong tooth, main flagellum shorter than last article of peduncle, accessory flagellum tiny.

Maxilliped 2 with pappose long seta on inner distal corner of basis and merus, carpus 2nd longest article, with pappose setae on inner margin, dactylus half length of propodus, with stout terminal seta. Maxilliped 3 basis longer than rest of articles combined, with 4 plumose setae along distal margin (2 much longer), merus as long as carpus, with plumose seta on outer margin of both, propodus 2nd longest article, dactylus little less than half as long as propodus, with longer stout terminal setae.

Pereopod 1 basis less than half as long as appendage, merus more than twice length of ischium, carpus 1.8 times as long as merus, as long as propodus, twice as long as dactylus, dactylus with terminal stout curved seta. Pereopod 2 basis 3rd of appendage length, fine seta on inner margin of merus, carpus 3 times as long as merus, with 2 stout setae on inner distal corner, dactylus onefourth as long as propodus, with subterminal long plumose seta (less than half of dactylus). Pereopod 3 basis longer than half of entire pereopod, carpus 3 times as long as merus, propodus little longer than merus, with distal stout seta, dactylus with terminal stout seta. Pereopod 4 with shorter basis and carpus longer than in previous pair. Pereopod 5 much shorter than previous pairs, basis half of appendage, terminal seta missing (limb is regenerated or individual is first molt after manca 2). Exopods on maxilliped 3 and pereopods 1, 2; with 2nd article very long.

Uropod peduncle 2.9 times as long as pleonite 6 and 1.3 times as long as its equal rami, fine setae on both sides, exopod with terminal stout seta (one-third of exopod length), endopod with 2 pedunculate setae, 2 slender simple and 2 stout setae on inner margin and longer terminal seta (as in exopod).

Description of male. Body with knotty surface only on pleonite 4. Length: 5.1 mm. Carapace, pseudorostrum with long setae, large lateral swelling on branchial region, more pronounced anterolateral corner, smooth lower margin.

Antenna 1 with similar peduncle, main flagellum longer than in female. Antenna 2 (fig. 59c) with ranks of setae on articles 2–5 of peduncle.

Maxilliped 2 with larger articles, more setulose. Maxilliped 3 with longer basis.

Pereopod 1 as in female, carpus and propodus equal, longer than in female (3 times as long as merus), with shorter dactylus. Pereopod 2 as in female, subterminal seta of dactylus simple, not plumose. Pereopods 3 and 4 with large basis, longer than rest of appendage in 3rd pair, shorter in 4th, carpus 3 times as long as merus in 3rd pair, 4.5 times longer in 4th pair, long stout terminal seta. Pereopod 5 with shorter and more slender basis than in previous pairs, carpus 5 times as long as merus, propodus 0.4 of carpus. Exopods, 5 pairs, stronger than in female.

Uropod peduncle with straight margins, 2.7 times as long as pleonite 6, 1.4 times as long as endopod, exopod little shorter than endopod, endopod with 5 setae on inner margin.

Etymology. The name “ nodosum ” means “knotty” in Latin and describes the body surface.

Distribution. S of Point Hicks, Vic.; 1500 m depth.

Remarks. Styloptocuma nodosum differs from other species in this paper in its knotty integument, a carapace without spines, its slightly serrated lower margin of the carapace in females, being without an antennal notch and with a more upturned pseudorostrum. It resembles S. extans Jones, 1984 from the deep Atlantic but has a shorter pseudorostrum, the integument not knotty, and a spiny pleon.

Figures

Figure 57. Styloptocuma nodosum sp. nov. female holotype: a, body, lateral view; b, antenna 1; c, maxilliped 2; d, maxilliped 3. Scale (in mm): a, 0.5; b, d, 0.5; c, 0.2.

Figure 58. Styloptocuma nodosum 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–f, 0.5.

Figure 59. Styloptocuma nodosum sp. nov. male allotype: a, body, lateral view; b, antenna 1; c, antenna 2; d, maxilliped 2. Scale (in mm): a, 1; b, 0.25; c, 0.5; d, 0.2.

Figure 60. Styloptocuma nodosum sp. nov. male allotype: a, maxilliped 3; b, pereopod 1; c, pereopod 2; d, pereopod 3; e, pereopod 4; f, pereopod 5; g, pleonite 6 and left uropod. Scale (in mm): a, c–g, 0.5; b, 0.5.