Australorchestia tantabiddyensis, Lowry, J. K. & Springthorpe, R. T., 2015

Lowry, J. K. & Springthorpe, R. T., 2015, Coastal Talitridae (Amphipoda: Talitroidea) from north-western Australia to Darwin with a revision of the genus Cochinorchestia Lowry & Peart, 2010, Zootaxa 3985 (2), pp. 151-202 : 155-160

Australorchestia tantabiddyensis sp. nov.

( Figs 1–4 )

Type material. Holotype, male, 12 mm, WAM C59004, Tantabiddy Rockholes Cave C.332, Northwest Cape Peninsula, Western Australia (21°55'S 113°59'E), coll. M. Newton and K. Cameron, 15 August 1992. Paratypes: 1 female, WAM C59005, 2 males, WAM C59006, same locality.

Type locality. Tantabiddy Rockholes Cave, Northwest Cape Peninsula, Western Australia (21°55'S 113°59'E).

Habitat. Cave-hoppers.

Etymology. Named for Tantabiddy, the area of the type locality.

Description. Based on holotype, male, 12 mm, WAM C59004.

Head slender scales on ventroproximal surface unknown. Antenna 1 short, not longer than article 4 of antenna 2 peduncle. Antenna 2 less than half body length; peduncular articles slender, article 5 longer than article 4, peduncular articles with sparse, small robust setae, final article cone-shaped, forming virgula divina. Mandible left lacinia mobilis 5-dentate. Maxilla 1 with small 2-articulate palp. Maxilliped palp article 2 distomedial lobe well developed; article 4 reduced, button-shaped.

Pereon. Gnathopod 1 sexually dimorphic; chelate; coxa smaller than coxa 2; posterior margin of carpus and propodus each with lobe covered in palmate setae, palmate lobes in male only; carpus longer than propodus, 1.3 × as long as propodus, 1.8 × as long as broad; propodus 'subtriangular' with well developed posterodistal lobe, anterior margin with 2 groups of robust setae, lateral surface with 6 cuspidate setae; with 8 serrate setae, palm obtuse, without spine patch on posterodistal corner; dactylus longer than palm without anterodistal denticular patch. Gnathopod 2 sexually dimorphic; subchelate; coxal gill simple (or slightly lobate); basis slightly expanded; ischium without lobe on anterior margin, without anterodistal lobe on medial surface; merus without distally rounded posterodistal lobe on medial surface; carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus subovate, 1.6 × as long as wide, palm acute, reaching about 34% along posterior margin, with sinus midway, with rounded protuberance near dactylar hinge and deep sinus midway along palm, with 2 groups of robust setae (9, 5 lateral 7, 2 medial), with large midpalmar sinus, without midpalmar protuberances, posteromedial surface of propodus with groove, with cuticular patch at corner of palm; dactylus attenuated distally. Pereopods 2–4 coxae as wide as deep. Pereopods 3–7 dactyli without anterodistal denticular patch. Pereopod 4 subequal in length to pereopod 3; carpus similar in length to pereopod 3 carpus; dactylus thickened proximally with a notch midway along posterior margin.

Pereopod 5 propodus distinctly longer than carpus. Pereopods 6–7 not sexually dimorphic. Pereopod 6 slightly shorter than pereopod 7; coxa posterior lobe inner view posteroventral corner subquadrate, posterior margin perpendicular to ventral margin, posterior lobe with ridge, posterior lobe without marginal setae. Pereopod 7 basis lateral sulcus absent, posterodistal lobe present; merus posterior margin expanded distally, subtriangular.

Pleon. Epimeron 2 subequal in length to epimeron 3. Epimeron 3 posterior margin smooth, with 1 tiny seta, posteroventral corner narrowly rounded. Uropod 1 peduncle with 8 robust setae, distolateral robust seta present, large (1/4 length of outer ramus), with simple tip; inner ramus subequal in length to outer ramus, inner ramus with 4 marginal robust setae in 1 row; outer ramus with 4 marginal robust setae. Uropod 2 peduncle with 4 robust setae; inner ramus subequal in length to outer ramus, with 2 marginal robust setae; outer ramus with 2 marginal robust setae in 1 row. Uropod 3 peduncle with 1–3 robust setae; ramus partially fused dorsally to peduncle, subequal in length to peduncle, ramus 2–2.2 × as long as broad, ramus linear (tapering distally), with 2 apical setae. Telson as broad as long, apically incised, dorsal midline entire, with 5–6 marginal and apical robust setae per lobe.

Female (sexually dimorphic characters). Based on paratype female, WAM C59005. Gnathopod 1 parachelate; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; propodus anterior margin with 2 groups of robust setae. Gnathopod 2 mitten-shaped; ischium without lobe on anterior margin; posterior margin of carpus and propodus each with lobe covered in palmate setae; carpus well developed (not enclosed by merus and propodus), posterior lobe present, projecting between merus and propodus; palm obtuse, nearly straight; dactylus curved, posterior margin smooth. Oostegites unknown.

Remarks. Australorchestia tantabiddyensis sp. nov. differs from A. occidentalis in having a 5-cuspidate lacinia mobilis (4-cuspidate in A. occidentalis ) and in having robust setae on the outer ramus of uropod 2 (without setae in A. occidentalis ).

Distribution. Australia. Tantabiddy Rockholes Cave, Northwest Cape Peninsula, Western Australia (this study).

Figures

FIGURE 1. Australorchestia tantabiddyensis sp. nov., male, holotype, 12 mm, WAM C 59004, Northwest Cape Peninsula, Western Australia. Scale line for A 1 represents 0.2 mm, A 2 represents 0.5 mm, remainder represent 0.1 mm.

FIGURE 2. Australorchestia tantabiddyensis sp. nov., male, holotype, 12 mm, WAM C 59004, Northwest Cape Peninsula, Western Australia. Scale line for T represents 0.1 mm, CT represents 0.01 mm, remainder represent 0.2 mm.

FIGURE 3. Australorchestia tantabiddyensis sp. nov., male, holotype, 12 mm, WAM C 59004; female, paratype, WAM C 59005; Northwest Cape Peninsula, Western Australia. Scale lines for female G 1 – 2 represents 0.2 mm, remainder represent 0.5 mm.

FIGURE 4. Australorchestia tantabiddyensis sp. nov., male, holotype, 12 mm, WAM C 59004, Northwest Cape Peninsula, Western Australia. Scale lines represent 0.5 mm.