Cochinorchestia lindsayae, 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 : 161

Cochinorchestia lindsayae sp. nov.

( Figs 5 , 6 )

Types. Holotype, male, 6.5 mm, MAGNT Cr018586, Jones Creek, Middle Arm, Darwin Harbour, Northern territory, Australia (12°33.83'S 130°53.6'E), among the mangrove apple ( Sonneratia alba ) dominated community, coll. K. Metcalfe, station M38. Paratypes: 1 male, 1 juvenile female, MAGNT Cr018587, same locality.

Type locality. Jones Creek, Middle Arm, Darwin Harbour, Northern territory, Australia (12°33.83'S 130°53.6'E).

Etymology. Named for Sue Lindsay, in appreciation of her support of our talitrid project and her superb SEM micrographs of our talitrid amphipods.

Habitat. Mangrove tidal flat, among the mangrove apple ( Sonneratia alba ) and the stilted mangrove ( Rhizophora stylosa ) dominated community.

Description. Based on holotype, male, 6.5 mm, MAGNT Cr018586.

Head ventroproximal scales unknown. Antenna 1 reaching slightly beyond end antenna 2 peduncle. Antenna 2 peduncular articles slender; flagellum virgula divina absent. Mandible left lacinia mobilis unknown. Maxilla 1 palp unknown. Maxilliped palp article 2 distomedial lobe well developed; article 4 small, well defined.

Pereon. Gnathopod 1 sexually dimorphic; subchelate; coxa smaller than coxa 2; posterior margin of merus, carpus and propodus each with lobe covered in palmate setae; carpus longer than propodus, 1.7 × as long as propodus, 2.3 × as long as broad; propodus 'subtriangular' with well developed posterodistal lobe, anterior margin with 1 group of robust setae, medial surface with 5 cuspidate setae, posteromedial surface with 7 serrate setae, posterior margin without cuspidate setae, posterior margin without serrate setae, palm transverse, with 7 serrate setae, without spine patch on posterodistal corner; dactylus subequal in length to palm; simplidactylate, without anterodistal denticular patch. Gnathopod 2 sexually dimorphic; subchelate; basis slightly expanded; ischium without lobe on anterior margin, with distally rounded anterodistal lobe on medial surface; carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus subovate, 1.8 × as long as wide, palm extremely acute, reaching about 54% along posterior margin, strongly toothed, incised with broad distal shelf, small sinus, tooth, slightly larger sinus, smaller tooth and broad subquadrate gap, lined with robust setae (6 medial, 9 lateral), posteromedial surface with groove, with cuticular patch at corner of palm; dactylus slightly longer than palm, curved, without anteroproximal bump, posterior margin smooth, not modified distally, blunt. Pereopods 3–7 dactyli without anterodistal denticular patch. Pereopod 4 dactylus similar to pereopod 3, not thickened proximally or notched. Pereopod 5 propodus longer than carpus. Pereopod 6 slightly shorter than pereopod 7; coxa posteroventral corner with small cusp, posterior margin perpendicular to ventral margin, posterior lobe without marginal setae. Pereopod 7 distal articles slender; basis lateral sulcus absent, posterodistal lobe reaching beyond merus; merus not expanded; propodus without distal tuft of setae.

Pleon. Epimeron 3 posterior margin smooth, without setae, posteroventral corner subquadrate. Uropod 1 peduncle with 8 robust setae, distolateral robust seta present, very large (1/3 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 2 marginal robust setae. Uropod 2 peduncle with about 4 setae; inner ramus subequal in length to outer. Uropod 3 peduncle with 1 robust seta; ramus not fused to peduncle, shorter than peduncle, 2.7 × as long as broad, linear (tapering distally), with 3 apical setae. Telson broader than long, entire, dorsal midline absent, with 2 pair of apical robust setae.

Remarks. Cochinorchestia lindsayae sp. nov. is part of the species group with a distal shelf on the propodus palm of male gnathopod 2. Like C. notabilis it has only one robust seta on the ramus of uropod 3. Cochinorchestia lindsayae differs from C. notabilis in having subacute teeth on palm (acute in C. notabilis ) of gnathopod 2 with a broad proximal gap (narrow in C. notabilis ).

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

Figures

FIGURE 5. Cochinorchestia lindsayae sp. nov., male, holotype, 6.5 mm, MAGNT Cr 018586; * male, paratype, MAGNT Cr 018587; Jones Creek, Middle Arm, Darwin Harbour, Northern territory, Australia. Scale line for MX 1 IP represents 0.05 mm, remainder represent 0.1 mm.

FIGURE 6. Cochinorchestia lindsayae sp. nov., male, holotype, 6.5 mm, MAGNT Cr 018586, Jones Creek, Middle Arm, Darwin Harbour, Northern territory, Australia. Scale line for G 1 represents 0.2 mm, remainder represent 0.5 mm.