© Copyright Australian Museum, 2006 Records of the Australian Museum (2006) Vol. 58: 97–118. ISSN 0067-1975 The Amphipod Genus Arcitalitrus (Crustacea: Amphipoda: Talitridae) of New South Wales Forests, With Descriptions of Six New Species R. PEART AND J.K. LOWRY* Aquatic Zoology, Australian Museum, 6 College Street, Sydney NSW 2010, Australia [email protected] · [email protected] ABSTRACT. Until now, the genus Arcitalitrus has been restricted to three species, Ar. bassianus Friend, 1987, Ar. dorrieni (Hunt, 1925) and Ar. sylvaticus (Haswell, 1879). We redescribe the type species Ar. sylvaticus (Haswell, 1879) and describe six new species (Ar. belbucca, Ar. bundeena, Ar. moonpar, Ar. nana, Ar. orara, and Ar. thora) from New South Wales state forests and the Royal National Park, near Sydney. PEART, R., & J.K. LOWRY, 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(1): 97–118. Including this paper, 32 species of terrestrial Talitridae species, Arcitalitrus dorrieni (Hunt, 1925) from Blackheath, (landhoppers) are described from Australia (Haswell, 1879; New South Wales and Ar. bassianus Friend, 1987, from Bousfield, 1976; Friend, 1979, 1982, 1987). Most species Victoria and northwestern Tasmania. The type species, Ar. are known from Tasmania (Friend, 1979, 1987). Apart from sylvaticus (Haswell, 1879) has never been precisely introduced terrestrial species, the New South Wales fauna described. In this paper, we redescribe Ar. sylvaticus based appears to be restricted to species of Arcitalitrus and on new collections from the type locality and establish a Agilestia and species of the former apparently dominate neotype to distinguish it from other closely related species. the amphipod component of the forest floor community. Arcitalitrus appears to have two groups. The “Sylvaticus” Including the new taxa described here, 12 species of talitrids species group is defined by gill 6 that has a convoluted anterior are known from New South Wales: Arcitalitrus belbucca margin and a subapically incised posterior margin and the rami n.sp., Ar. bundeena n.sp., Ar. dorrieni (Hunt, 1925), Ar. of pleopod 3 that are subequal in length to the peduncle. This moonpar n.sp., Ar. nana n.sp., Ar. orara n.sp., Ar. sylvaticus group contains Ar. bassianus, Ar. belbucca, Ar. nana, Ar. orara, (Haswell, 1879), Ar. thora n.sp., Agilestia hylaea Friend, and Ar. sylvaticus. The “Dorrieni” species group contains Ar. 1982, Parorchestia gowerensis Bousfield, 1976, from Lord dorrieni and Ar. moonpar and is defined by epimeron 2 that is Howe Island, and the introduced species Talitroides alluaudi longer than epimeron 3, a subquadrate posteroventral corner (Chevreux, 1901) and T. topitotum (Burt, 1934). on epimeron 3 and an entire telson. The long epimeron 2 and Hurley (1975) established the subgenus Talitrus the subquadrate corner of epimeron 3 are homoplastic (Arcitalitrus) for T. sylvaticus Haswell, 1879, a terrestrial characters that also occur in Ar. bassianus. Arcitalitrus species originally known from Rooty Hill, just west of bundeena and Ar. thora apparently belong in neither group. Sydney, New South Wales. Friend (1987) elevated the Neither species has the characters that define the “Sylvaticus” subgenus to generic status and included two additional and “Dorrieni” species groups. * author for correspondence www.amonline.net.au/pdf/publications/1459_complete.pdf 98 Records of the Australian Museum (2006) Vol. 58 The taxonomic descriptions and diagnoses presented in Taxonomy this paper were generated from a DELTA (Dallwitz et al., Arcitalitrus Hurley 1993) database of Australian talitrid amphipod species. Each Arcitalitrus Hurley, 1975: 161.–Friend, 1987: 35. species is diagnosed against all other species in the genus Arcitalitrus. Bold phrases in the descriptions indicate Type species. Talitrus sylvaticus Haswell, 1879, original diagnostic characters. Material included in this study is designation. lodged in the Australian Museum, Sydney (AM), the Natural Diagnosis. Gnathopod 2 not sexually dimorphic. Maxilliped History Museum, London, (BMNH) and the National outer plate distally acute/arcuate. Pleopods 1 and 2 well Museums of Canada, Ottawa (NMC). The following developed, pleopod 3 reduced. abbreviations are used on the plates: A, antenna; EP, epimeron; Species composition. Arcitalitrus contains nine species: Ar. gi, gill; G, gnathopod; LL, lower lip; MD, mandible; MP, bassianus Friend, 1987; Ar. belbucca n.sp.; Ar. bundeena n.sp.; maxilliped; MX, maxilla; O, oostegite; P, pereopod; PL, Ar. dorrieni (Hunt, 1925); Ar. moonpar n.sp.; Ar. nana n.sp.; pleopod; T, telson; UL, upper lip; U, uropod; l, left; r, right. Ar. orara n.sp.; Ar. sylvaticus (Haswell, 1879); Ar. thora n.sp. Key to the species of the genus Arcitalitrus 1 Epimeron 3 posteroventral margin serrulate ............................................... Arcitalitrus bassianus —— Epimeron 3 posteroventral margin smooth ................................................................................... 2 2 Epimeron 2 subequal in length to epimeron 3............................................................................... 3 —— Epimeron 2 longer than epimeron 3 .............................................................................................. 6 3 Gill 6 anterior margin convoluted, subapically incised ................................................................. 4 —— Gill 6 posterior margin convoluted, apically incised.......................................... Arcitalitrus thora 4 Pleopod 3 rami absent .................................................................................................................... 5 —— Pleopod 3 uniramous............................................................................................ Arcitalitrus nana 5 Telson entire ........................................................................................................ Arcitalitrus orara —— Telson apically incised ................................................................................. Arcitalitrus sylvaticus —— Telson deeply incised ..................................................................................... Arcitalitrus belbucca 6 Epimeron 3 posteroventral corner with subacute tooth............................... Arcitalitrus bundeena —— Epimeron 3 posteroventral corner rounded ................................................... Arcitalitrus moonpar —— Epimeron 3 posteroventral corner subquadrate .............................................. Arcitalitrus dorrieni Arcitalitrus bassianus Friend Pereopod 4 carpus similar in length to pereopod 3 carpus, dactylus similar to pereopod 3 dactylus. Pereopod 7 basis Talitrus sylvaticus.–Chevreux, 1901: 392, fig. 7. posterodistal lobe present. Gill 2 lobate, not incised. Gills Arcitalitrus bassianus Friend, 1987: 35, figs 30–35. 3–5 lobate, smaller than gills 2 and 6. Gill 6 lobate, anterior Type material. HOLOTYPE, Θ AM P37350, 10 February margin convoluted, subapically incised along posterior 1979, J.A. Friend. PARATYPES, male AM P37351; 3ΘΘ, 1 margin. Oostegites long (length greater than 2× width), juvenile AM P37352; 1Η, 2ΘΘ, 1 juvenile BMNH; 1Η, weakly setose, setae with simple smooth tips. Epimera 1 to 2ΘΘ, 1 juvenile NMC. Paratypes are all from type locality. 3 not convergent. Epimeron 2 longer than epimeron 3. Epimeron 3 posteroventral margin serrulate, postero- Type locality. 1.5 km NNE of Kate’s Point, Robbins Island, ventral corner subquadrate. Pleopod 1 well developed, northwestern Tasmania (40°40'S 144°55'E), in swampy area biramous, rami subequal in length to peduncle; inner ramus beside creek. with 5 articles; outer ramus with 9 articles. Pleopod 2 reduced, biramous, rami shorter than peduncle; inner ramus Description. Body shape laterally compressed; cuticle with 4 articles, inner ramus with 1–5 articles; outer ramus calcification absent. Eye medium (1⁄5–1⁄3 head length). with 6 articles. Pleopod 3 reduced, biramous, rami shorter Antenna 2 longer than head and first 3 pereonites; than peduncle; inner ramus with 2 articles; outer ramus with peduncular articles narrow. Mandible left lacinia mobilis 4 5 articles. Uropod 1 not sexually dimorphic; peduncle with dentate. Maxilliped outer plate distally acute/arcuate; palp 3 robust setae on peduncle; inner ramus subequal in length dactylus present and distinct. Pereonite 1 sternite without to outer ramus, with 3 robust setae on the margins, with 3 papillose process. Gnathopod 1 not sexually dimorphic; apical robust setae; outer ramus without marginal robust simple; merus and carpus not expanded; propodus setae, with 3 apical robust setae. Uropod 2 not sexually subrectangular; palm absent; dactylus longer than palm. dimorphic; peduncle with 3 robust setae; inner ramus Gnathopod 2 not sexually dimorphic; chelate; basis narrow; subequal in length to outer ramus, with 2 marginal robust merus and carpus expanded posteriorly; propodus “mitten- setae, 5 apical robust setae; outer ramus without marginal like”; palm obtuse; smooth; dactylus shorter than palm. robust setae, with 2 apical robust setae. Uropod 3 peduncle Pereopods 3–7 long (½ length of body); simplidactylate. with 1 robust seta; ramus shorter than peduncle, ramus linear Peart & Lowry: Talitrid amphipods of New South Wales forests 99 (narrowing), with 2 robust setae. Telson as broad as long, palm absent; dactylus longer than palm. Gnathopod 2 not apically incised, with