Spinarcturus Kensley, 1978

Poore, Gary C. B., 2015, Thermoarcturidae, a new crustacean family of three genera (Isopoda: Valvifera), Zootaxa 4007 (3), pp. 409-418 : 412

Spinarcturus Kensley, 1978

Spinarcturus Kensley, 1978a: 135 .

Type species. Spinarcturus natalensis Kensley, 1978 , by original designation and monotypy.

Diagnosis. Pereonites 2–4 with prominent sublateral and lateral spines; pereonites 5–7 with prominent lateral spines; pleonite 3 with pair of acute sublateral spines, longer and stouter than other spines; pleotelson unarmed. Eyes present. Male pleopod 1 exopod with area of fine setae about one third along, groove weakly defined. Oostegites 5 apparent as pair of small flaps on anterior margin of pereonite 5.

Remarks. The genus, represented by one species, is included in the new family largely because of the absence of ‘filter setae’, the covering of setules and the short uropodal rami. It differs from the other two in not having an obvious groove on the posterior face of the male pleopod 1 but instead a broad proximal depression filled with fine setae. This resembles the structure seen in species of Arcturus (family Arcturidae ), e.g., A. baffini (Sabine, 1824) (see Kussakin 1982: fig. 238) but these have rows of numerous ‘filter setae’ on pereopods 2–4. Kensley (1978a) characterised the genus having pereonite 1 not fused with the head. While a clear furrow is visible dorsally there is not articulation as is typical of all arcturoid valviferans. He noted the difficulty of placing the type species and compared it with several genera now included in Arcturidae , Antarcturidae and Holidoteidae before erecting a new genus.