Arcitalitrus bassianus Friend, 1987

R Peart, 2006, The Amphipod Genus Arcitalitrus (Crustacea: Amphipoda: Talitridae) of New South Wales Forests, With Descriptions of Six New Species, Records of the Australian Museum 58, pp. 97-118 : 98-99

Arcitalitrus bassianus Friend

Talitrus sylvaticus .– Chevreux, 1901: 392, fig. 7.

Arcitalitrus bassianus Friend, 1987: 35 , figs 30–35.

Type material. HOLOTYPE, ♀ AM P37350, 10 February 1979, J.A. Friend . PARATYPES, male AM P37351 ; 3♀♀, 1 juvenile AM P37352 ; 13, 2♀♀, 1 juvenile BMNH ; 13, 2♀♀, 1 juvenile NMC. Paratypes are all from type locality.

Type locality. 1.5 km NNE of Kate’s Point, Robbins Island , northwestern Tasmania (40°40'S 144°55'E), in swampy area beside creek .

Description. Body shape laterally compressed; cuticle calcification absent. Eye medium (1 ⁄ 5 – 1 ⁄ 3 head length). Antenna 2 longer than head and first 3 pereonites; peduncular articles narrow. Mandible left lacinia mobilis 4 dentate. Maxilliped outer plate distally acute/arcuate; palp dactylus present and distinct. Pereonite 1 sternite without papillose process. Gnathopod 1 not sexually dimorphic; simple; merus and carpus not expanded; propodus subrectangular; palm absent; dactylus longer than palm. Gnathopod 2 not sexually dimorphic; chelate; basis narrow; merus and carpus expanded posteriorly; propodus “mittenlike”; palm obtuse; smooth; dactylus shorter than palm. Pereopods 3–7 long (½ length of body); simplidactylate. Pereopod 4 carpus similar in length to pereopod 3 carpus, dactylus similar to pereopod 3 dactylus. Pereopod 7 basis posterodistal lobe present. Gill 2 lobate, not incised. Gills 3–5 lobate, smaller than gills 2 and 6. Gill 6 lobate, anterior margin convoluted, subapically incised along posterior margin. Oostegites long (length greater than 2× width), weakly setose, setae with simple smooth tips. Epimera 1 to 3 not convergent. Epimeron 2 longer than epimeron 3. Epimeron 3 posteroventral margin serrulate, posteroventral corner subquadrate. Pleopod 1 well developed, biramous, rami subequal in length to peduncle; inner ramus with 5 articles; outer ramus with 9 articles. Pleopod 2 reduced, biramous, rami shorter than peduncle; inner ramus with 4 articles, inner ramus with 1–5 articles; outer ramus with 6 articles. Pleopod 3 reduced, biramous, rami shorter than peduncle; inner ramus with 2 articles; outer ramus with 5 articles. Uropod 1 not sexually dimorphic; peduncle with 3 robust setae on peduncle; inner ramus subequal in length to outer ramus, with 3 robust setae on the margins, with 3 apical robust setae; outer ramus without marginal robust setae, with 3 apical robust setae. Uropod 2 not sexually dimorphic; peduncle with 3 robust setae; inner ramus subequal in length to outer ramus, with 2 marginal robust setae, 5 apical robust setae; outer ramus without marginal robust setae, with 2 apical robust setae. Uropod 3 peduncle with 1 robust seta; ramus shorter than peduncle, ramus linear (narrowing), with 2 robust setae. Telson as broad as long, apically incised, with marginal and apical robust setae, with 3–5 robust setae per lobe.

Habitat. Leaf and log litter, in bracken, under stones, swampy ground, wet sclerophyll, eucalyptus regrowth.

Remarks. Arcitalitrus bassianus is a member of the “Sylvaticus” species group and is the only Australian landhopper found on both mainland Australia and Tasmania. It differs from other species in the group in having a long epimeron 2, a subquadrate corner on epimeron 3, reduced numbers of articles on the inner ramus of pleopod 2 and a biramous pleopod 3. It is similar to Ar. belbucca and Ar. nana in having 6–10 articles on the outer ramus of pleopod 2. Arcitalitrus bassianus and Ar. sylvaticus both have subequal rami on uropod 1 and an apically incised telson.

Distribution. Tasmania: Teatree swamp near Togari; King and Robbins Islands ( Friend, 1987). Victoria: Mount Donna Buang; Marysville; Cement Creek; Nelson; Lake Purrumbete; Snobs Creek ( Friend, 1987).