Tropicorchestia glasbyi, 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 : 197-200

Tropicorchestia glasbyi sp. nov.

( Figs 30–33 )

Type material. Holotype, male, 8.0 mm, MAGNT Cr018599, opposite port, Wickham Point, Darwin Harbour, Northern Territory, Australia (12°31.202 'S 130°52.403 'E), hinterland margin, K. Metcalfe, 2001, LG 36. Paratypes: 2 females, MAGNT Cr018600, same locality.

Type locality. Hinterland margin opposite port, Wickham Point, Darwin Harbour, Northern Territory, Australia (12°31.202 'S 130°52.403 'E).

Etymology. Named for Chris Glasby, in appreciation of his contribution to Australian polychaete systematics and his support of our amphipod projects in the Northern Territory.

Habitat. Marsh-hoppers. Supralittoral living in hinterland margin.

Description. Based on holotype, male, 8.0 mm, MAGNT Cr018599.

Head slender scales on ventroproximal surface unknown. Antenna 1 short, not reaching end of antenna 2 peduncular article 4. Antenna 2 slightly less than half body length; article 5 longer than article 4, peduncular articles with sparse large robust setae; final flagellar article large, cone-shaped, forming virgula divina. Upper lip without robust setae; epistome without many pores; without setal patches. Lower lip with vestigial inner plates. Mandible left lacinia mobilis 4-cuspidate. Maxilla 1 with small palp, 2-articulate. Maxilliped palp article 2 distomedial lobe well developed; article 4 reduced, button-shaped.

Pereon. Gnathopod 1 subchelate; coxa smaller than coxa 2; posterior margin of merus, carpus and propodus each with lobe covered in palmate setae (merus vestigial); carpus longer than propodus, 1.4 × as long as propodus, 2.2 × as long as broad; propodus 'subtriangular' with well developed posterodistal lobe, anterior margin with 2 groups of robust setae, medial surface with 15 cuspidate setae, posterior margin with 6 cuspidate setae, palm with 7 serrate setae, transverse, without spine patch on posterodistal corner; dactylus subequal in length to palm, without anterodistal denticular patch. Gnathopod 2 sexually dimorphic; subchelate; basis slightly expanded; ischium with rounded lobe on mid-anterior margin, distal triangular anterodistal lobe on medial surface (forming a cradle); carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus subovate, 1.4 × as long as wide; palm acute, reaching about 36% along posterior margin, smooth, evenly rounded, lined with robust setae (7 large, 7 small lateral and 6 large, 10 small medial), posteromedial surface of propodus with groove, with cuticular patch at corner of palm; dactylus longer than palm, curved, without anteroproximal bump, posterior margin with minute cuticular surface, attenuated distally. Pereopods 2–4 coxae wider than deep, or as wide as deep, or deeper than wide. Pereopods 3–7 cuspidactylate; each dactylus without anterodistal denticular patch. Pereopod 4 subequal to pereopod 3; carpus similar in length to pereopod 3 carpus; dactylus slightly thickened proximally with slight notch midway along posterior margin. Pereopod 5 propodus distinctly longer than carpus. Pereopods 6–7 not sexually dimorphic, longer than pereopods 3–5. Pereopod 6 similar in length to pereopod 7; coxa posterior lobe inner view posteroventral corner rounded, posterior margin perpendicular to ventral margin, posterior lobe without ridge. Pereopod 7 basis lateral sulcus absent, posterior margin with distinct minute serrations, each with a small seta, posterodistal lobe present, shallow, narrowly rounded; propodus setation without large distal tuft of setae.

Pleon. Pleopods 1–3 all well developed, biramous. Epimeron 2 slightly longer than epimeron 3. Epimeron 3 posterior margin smooth, without setae, posteroventral corner with small subacute tooth. 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 without 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 3 marginal robust setae in 1 row. Uropod 3 peduncle with 2 robust setae; ramus not fused to peduncle, shorter than peduncle, 1.4 × as long as broad, linear (tapering distally). Telson longer than broad, apically incised, dorsal midline entire, with 4 robust setae per lobe (2 lateral and 2 apical).

Female (sexually dimorphic characters). Based on paratype female, MAGNT Cr018600. Gnathopod 1 parachelate; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; propodus anterior margin with 3 groups of robust setae; dactylus longer than palm. Gnathopod 2 mitten-shaped; basis slightly expanded; ischium without lobe on anterior margin; posterior margin of merus, 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, shorter than palm. Oostegites long (length greater than 2 × width), longer than wide, weakly setose, setae with simple smooth tips.

Remarks. See T. derbyensis sp. nov.

Distribution. Australia. Darwin Harbour, Northern Territory (this study).

Figures

FIGURE 30. Tropicorchestia glasbyi sp. nov., male, holotype, 8.0 mm, MAGNT Cr 018599, Darwin Harbour, Northern Territory, Australia. Scale line for H represents 0.5 mm, remainder represent 0.1 mm.

FIGURE 31. Tropicorchestia glasbyi sp. nov., male, holotype, 8.0 mm, MAGNT Cr 018599, Darwin Harbour, Northern Territory, Australia. Scale lines for U 1, U 2 represent 0.2 mm, remainder represent 0.1 mm.

FIGURE 32. Tropicorchestia glasbyi sp. nov., male, holotype, 8.0 mm, MAGNT Cr 018599; female, paratype, MAGNT Cr 018600; Darwin Harbour, Northern Territory, Australia. Scale lines for G 1 represent 0.2 mm, scale lines for G 2 represent 0.5 mm.

FIGURE 33. Tropicorchestia glasbyi sp. nov., male, holotype, 8.0 mm, MAGNT Cr 018599, Darwin Harbour, Northern Territory, Australia. Scale lines represent 0.5 mm.