Arcitalitrus thora, R Peart, 2006

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 : 106

Arcitalitrus thora n.sp.

Figs. 7, 27–29

Type material. HOLOTYPE, ♀, 13.0 mm, AM P60965, M. Gray, G. Milledge and H. Smith December 1999 . PARATYPES 15 specimens AM P60966 . Paratypes are all from the type locality.

Type locality. Horseshoe Road , 3.5 km southeast of Thora, Scotchman State Forest (30°26'25"S 152°47'30"E) .

Description. Based on holotype female. Body shape normally laterally compressed; cuticle calcification absent. Eye large (greater than 1 ⁄ 3 head length). Antenna 2 longer than head and first 3 pereonites; peduncular articles narrow. Mandible left lacinia mobilis 5 dentate. Maxilliped outer plate distally acute/arcuate; palp dactylus present and distinct. 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; narrow; merus and carpus expanded posteriorly; propodus “mitten-like”; 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 posterodistal lobe present. Gill 2 lobate, not incised. Gills 3–5 lobate, smaller than gills 2 and 6. Gill 6 lobate, posterior margin convoluted, apically incised. Oostegites long (length greater than 2× width), weakly setose, setae with simple smooth tips. Epimera 1 to 3 not convergent. Epimeron 2 subequal in length to epimeron 3. Epimeron 3 posteroventral margin smooth, posteroventral corner with small subacute tooth. Pleopod 1 well developed, biramous, rami shorter than peduncle; inner ramus with 12 articles; outer ramus with 9 articles. Pleopod 2 well developed, biramous, rami shorter than peduncle; inner ramus with 12 articles; outer ramus with 11 articles, outer ramus with more than 10 articles. Pleopod 3 reduced, rami absent. Uropod 1 not sexually dimorphic; peduncle with 4 robust setae on peduncle; inner ramus subequal in length to outer ramus, with 3 robust setae on the margins, with 3–5 robust setae, with 4 apical robust setae; outer ramus without marginal robust setae, with 4 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, 3 apical robust setae; outer ramus without marginal robust setae, with 3 apical robust setae. Uropod 3 peduncle with 1 robust setae; ramus shorter than peduncle, ramus bud-like (broad), with 2 robust setae. Telson longer than broad, apically incised, with marginal and apical robust setae, with 3–5 robust setae per lobe.

Etymology. Named for the village of Thora, near Scotchman State Forest, the type locality and treated as a noun in apposition.

Habitat. Forest floor leaf-litter.

Remarks. Arcitalitrus thora appears to be isolated from other Arcitalitrus species. It is excluded from the “sylvaticus” species group because it has smooth anterior margin on gill 6 with an apical incision, and the rami of pleopod 1 are shorter than the peduncle. It is excluded from the “Dorrieni” species group because epimeron 2 is subequal in length to epimeron 3, epimeron 3 has a small posteroventral cusp and the telson is apically incised. It is excluded from both groups by the convoluted posterior margin on gill 6 and the large number of articles in the outer ramus of pleopod 2 and the large number of robust setae on the inner ramus of uropod 2.

Distribution. New South Wales: Scotchman State Forest.

ACKNOWLEDGMENTS. We thank Tony Friend who generously shared his unpublished information on terrestrial talitrids with us. Funding was provided through the New South Wales Biodiversity Strategy for the taxonomy of terrestrial invertebrates. We would also like to thank our Australian Museum colleagues: Mike Gray, Graeme Milledge and Helen Smith who generously collected all the material allowing us to describe the new species.