Heteroserolis Brandt, 1991

Bruce, Niel, 2009, New genera and species of the marine isopod family Serolidae (Crustacea, Sphaeromatidea) from the southwestern Pacific, ZooKeys 18 (18), pp. 17-76 : 23

Heteroserolis Brandt, 1991

Heteroserolis Nordenstam, 1933: 50 (nomen nudum, type species not designated). Heteroserolis Brandt, 1991: 147 .– Brandt 1992: 230; Wägele 1994: 52.

Type species. Serolis australiensis Beddard, 1884 ; by subsequent designation ( Brandt 1991).

Species included. H. australiensis ( Beddard, 1884) , type species, South Australia, 2–124 m; H. carinata ( Lockington, 1877) , California 13–55 m; H. elongata ( Beddard, 1884) , New South Wales, Australia, 5–329 m; H. levidorsata ( Harrison and Poore, 1984) , Victoria, Australia, 13–14 m; H. longicaudata ( Beddard, 1884) , Bass Strait, Australia, 36–99 m; H. mgrayi (Menzies & Frankenberg, 1966) , Caribbean to Georgia, USA, 5–95 m; H. pallida ( Beddard, 1884) , Bass Strait, Australia, 55–104 m; H. pellucida sp. n., New Caledonia, 557–792 m; H. tropica ( Glynn, 1976) , Pacific Panama, 5–40 m; H. tuberculata ( Grube, 1875) , Bass Strait, Australia, 5– 91 m.

Remarks. The principal and diagnostic character states for Heteroserolis are the unique pleonal sternal plates 1 and 2 or 1–3, each with a strong posteriorly directed spine; long uropods that are inserted at mid-length on the pleotelson lateral margin, relatively broad pleonites that do not extend along the pleotelson lateral margins; and the narrow lacinia mobilis on the left mandible. A further character state, apparently common to all species of the genus is pleopod 4 exopod being comparatively elongate, approximately to 2.3 times as long as greatest width (compared to, for example, 1.8–1.9 for Myopiarolis gen. n.). Heteroserolis belongs within Wägele’s (1994) ‘Group B’ characterised by having a stalked appendix masculina. A further characteristic of the ‘Group B’ genera that also includes Serolina and Sedorolis gen. n. is the quadrate and elongate pleopods 1–3 peduncles.

The new species described is here placed in Heteroserolis on the basis of the pleonal sternal plates having a strong spine, and agrees with most other characters for the genus. It does differ in having a wide lacinia mobilis on the left mandible, distally acute pleonites, weakly concave lateral margins of the head (compared to strongly convex in most species of the genus), and the robust setae of pereopod 1 propodus differ substantially from that illustrated for the type species ( Brandt 1999).

The genus has an unusual and disjunct distribution, with six shallow-water species from Australia, a slope species from New Caledonia, two East Pacific species ( Panama and California) and one North Atlantic species.

The most recent descriptive works on the genus are Harrison and Poore (1984, as Serolis ), Müller (1993) and Brandt (1999); Brandt (1992) rediagnosed the genus.

Distribution. Species are known from shallow water, at depths between 18 and 140 m [with the exception of two records of H. elongata from the Bass Strait at 164– 273 and 73–329 m ( Harrison and Poore 1984)]; the new species described here extends the known depth range for the genus to 792 metres.