Spinarcturus natalensis Kensley, 1978

Poore, Gary C. B., 2015, Thermoarcturidae, a new crustacean family of three genera (Isopoda: Valvifera), Zootaxa 4007 (3), pp. 409-418 : 413-414

Spinarcturus natalensis Kensley, 1978

Fig. 3

Spinarcturus natalensis Kensley, 1978a: 136 –138, figs 7, 8.— Kensley 1978b: 33 –34, fig. 15F.

b g h i

c e f

p3

d p4 j

p5

Material examined. Holotype. South Africa, off Natal, 27°59’5, 32°40.8’E, 550 m (Meiring Naude stn SM 86), SAM A15473 (male, 6.0 mm). Paratype. Collected with holotype, SAM A15473 (ovigerous female, 8.2 mm). Other material. South Africa, off Natal (Meiring Naude stn SM 103), SAM A15474 (1 male, 2 juveniles).

Supplementary redescription. Pereopod 2 carpus twice as long as merus, convex along flexor margin; propodus almost as long a carpus, convex distally on flexor margin; dactylus with unguis as long as dactylus body; ischium with 1 marginal and 1 submarginal setae, merus with 2 marginal and 2 submarginal setae, carpus with 4 marginal and 3 submarginal setae, propodus with 3 marginal and 3 facial setae, dactylus with 3 marginal and 3 mesial facial seta. Pereopod 3 with similar setation, articles about as long but broader than those of pereopod 2. Pereopod 4 with similar setation to but distal articles especially shorter than pereopod 2. Pereopod 6 linear, 1.2 times as long as pereopod 2. Male pleopod 1 exopod thickened proximally, lamellar distally, with broad curved proximal depression on posterior face, filled with mat of long fine setae extending to mesial margin; exopod margin otherwise with plumose setae; endopod as long as exopod. Male pleopod 2 with appendix masculina simple, tapering, 1.8 times as long as endopod. Uropodal endopod subtriangular, with 2 or 3 distal robust setae, exopod slightly shorter than endopod, ovoid-tapering, with 2 distal robust setae.

Ovigerous female with ovoid oostegites on pereopods 1–4, each supported by oblique coxal spines, most prominent on pereopod 4; oostegite 5 an oval disc on anterior margin of pereonite 5 supported by short coxal projection.

Distribution. Indian Ocean, off South Africa, Natal; 550– 680 m.

Remarks. Examination of the male and female types confirmed most of Kensley’s (1978a) observations and illustrations. He mislabelled his illustration of pereopod 2 (fig. 8A) as ‘pereiopod VII’ and stated that ‘pereiopods II to IV essentially similar to pereiopods V to VII’. This is not so, pereopods 2–4 are stouter, with well-spaced long stiff setae arranged almost in pairs, while pereopods 5–7 are long, thin and with few short robust setae. Kensley did not figure the facial setae on distal articles but showed the tomentum of setules.