Spectrarcturus Schultz, 1981

Stransky, Bente, Svavarsson, Jörundur, Poore, Gary C. B. & Kihara, Terue Cristina, 2020, Revision of Pleuroprion zur Strassen, 1903 (Holidoteidae) and re-evaluation of Spectrarcturus Schultz, 1981 (Arcturidae) (Crustacea, Isopoda, Valvifera), Zootaxa 4894 (1), pp. 1-52 : 14-15

Genus Spectrarcturus Schultz, 1981

Spectrarcturus Schultz, 1981: 67 .

Spectarcturus .— Poore, 2001: 222 (incorrect spelling).

Diagnosis: Body cylindrical. Pereonite 1 fused to head, with shallow transverse groove on former suture line. Lateral margins of head and pereonite 1 margin deep, convex, embracing mouthparts and pereopod 1 laterally. Pereonite 4 longest, 2–4 times as long as pereonite 3. All pleonites fused with pleotelson, with at least 2 pairs of lateral wings. Antenna with large spines on peduncle articles 2 and 3; flagellum short, with 3 articles and 1 distal claw-like article in females; in males distal article spine-like. Pereopod 1 dactylus short, without unguis. Pereopods 2–4 not flexed between carpus and propodus, with paired long setae along lower margin; with small claw-like dactyli, with short unguis. Pereopods 5–7 dactyli with 2 ungues. Male pleopod 1 simple, exopod without diagonal groove.

Type species: Spectrarcturus multispinatus Schultz, 1981 = S. murdochi ( Benedict, 1898) .

Included species: Spectrarcturus murdochi ( Benedict, 1898) comb. nov.; Spectrarcturus chlebovitschi ( Kussakin, 1972) comb. nov.; Spectrarcturus fabulosus ( Gurjanova, 1955) comb. nov.; Spectrarcturus furcatus ( Kussakin, 1982) comb. nov.; Spectrarcturus hystrix ( Sars, 1877) comb. nov.; Spectrarcturus intermedius ( Richardson, 1899a) comb. nov.; Spectrarcturus iturupicus ( Kussakin & Mezhov, 1979) comb. nov.; Spectrarcturus toporoki ( Kussakin, 1972) comb. nov.

Remarks: The genus falls within Arcturidae as diagnosed by Poore (2001). Spectrarcturus resembles mostly Arcturus Latreille, 1829 , another genus largely confined to the Northern Hemisphere, with which it shares a lack of flexure between the carpus and propodus of pereopods 2–4. It differs in having a short antennal flagellum rather than multiarticulate as in Arcturus and absence of the dactylus on pereopod 1. Few species of Arcturus have lateral wings on the pleotelson ( Kussakin 1982).

All species occur in the Northern hemisphere, where six species ( S. chlebovitschi , S. fabulosus , S. furcatus , S. intermedius , S. iturupicus and S. toporoki ) occur in the northernmost North Pacific (Bering Sea, Kurile Islands, Aleutian Islands, Sea of Okhotsk), S. hystrix in the northernmost North Atlantic Ocean, and S. murdochi occurs widely in the North Pacific and in Arctic waters around Greenland. The latter species has not been reported in the high Arctic Ocean, between these regions. The centre of diversity is in the northernmost North Pacific.

The species are mostly shallow water species (several occurring as shallow as 5 or 6 meters), allowing dispersal through the shallow Bering Strait (maximum depths of around 53 m). Bering Strait first opened near the end of the Miocene at 5.32 MYA ( Gladenkov et al. 2002), but became later closed and reopened due to land-rise and glaciations, with the last opening about 11 cal ka BP ( Jakobsson et al. 2017) and lasting until the present.