Bellorchestia mariae, Lowry, 2012

Lowry, J. K., 2012, Talitrid amphipods from ocean beaches along the New South Wales coast of Australia (Amphipoda, Talitridae), Zootaxa 3575, pp. 1-26 : 3-6

Bellorchestia mariae sp. nov.

( Figs 1–3)

Type material. Holotype, male, 14.6 mm, AM P.87935, Honeymoon Bay , Jervis Bay, New south Wales, Australia (35°3'48"S 150°45'24"E), supralittoral zone burrowing in sand, 30 January 2011, Maria Capa . Paratypes: female, AM P.87934, juvenile male, AM P.87933, 18 males, 13 females, AM P.85301.

Additional material examined. 14 specimens, AM P.85880, Narrawallee Beach , New South Wales (35°18’27.7”S 150°28’21.2”E), 1305, oceanic beach under Cystophora in upper supralittoral zone, 30 April 2011, J.K. Lowry & A. Lodge, preserved in 95% ETOH (MI NSW 3690) .

Type locality. Honeymoon Bay , Jervis Bay, New South Wales, Australia (35°3'48"S, 150°45'24"E) .

Habitat. Under seaweed on sandy beach.

Etymology. Named for the collector, Maria Capa.

Description. Based on holotype male, 14.6 mm, AM P.87935.

Head. Eye medium (1/5–1/3 head length). Antenna 1 short, rarely longer than article 4 of antenna 2 peduncle. Antenna 2 up to half body length; peduncular articles slender; article 5 longer than article 4 (article 4 short). Mandible left lacinia mobilis 5-dentate. Maxilliped palp article 2 distomedial lobe well developed, 4 reduced, button-shaped.

Pereon. Gnathopod 1 sexually dimorphic; parachelate; coxa smaller than coxa 2, subtriangular, deeper than broad; posterior margin of propodus with lobe covered in palmate setae; propodus subrectangular, anterior margin with 6 groups of robust setae, medial surface with 10+ cuspidate setae; palm transverse, with 5 serrate setae; dactylus longer than palm. Gnathopod 2 sexually dimorphic; subchelate; coxa similar in size to coxa 3, about as broad as deep; basis slender; ischium and merus with distally rounded posterodistal lobe on medial surface; merus with distally rounded posterodistal lobe on medial surface; posterior margin of merus, carpus and propodus each without with lobe covered in palmate setae; 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 45% along posterior margin, weakly toothed, incised or sinuous, with 2 groups of robust setae, without protuberance near dactylar hinge, with small midpalmar protuberance with 9 or 10 robust setae, posterodistal corner defined by 2 slightly disjunct parallel ledges; posteromedial surface without groove; without cuticular patch at corner of palm; dactylus subequal in length to palm; gill lobate, 2 lobes, not incised. Pereopods 2–4 coxae slightly deeper than wide. Pereopods 3–5 gills simple or convoluted; smaller than gills 2 and 6. Pereopods 3–7 weakly cuspidactylate. Pereopods 3–7 dactyli without distal patch of many rows of tiny setae on the anterior margin. Pereopod 4 significantly shorter than pereopod 3; carpus significantly shorter than carpus of pereopod 3; thickened proximally with a notch midway along posterior margin; dactylus without anterodistal setal patch. Pereopod 5 propodus distinctly longer than carpus. Pereopod 6 subequal in length to pereopod 7; coxa posterior lobe inner view posteroventral corner rounded, posterior margin oblique to ventral margin, posterior lobe without ridge, posterior lobe with 5 or more marginal setae; coxal gill convoluted, coxal gill not incised; carpus slightly expanded. Pereopod 7 basis lateral sulcus present, slightly pronounced, posterodistal lobe present, rounded, produced downwards midway along ischium; merus and carpus slightly expanded; merus posterior margin straight; carpus forming a subtriangular plate.

Pleon. Pleopods all well developed. Pleopod 1 peduncle with marginal robust setae. Pleopods 1–3 biramous. Epimeron 2 slightly longer than epimeron 3. Epimeron 3 posterior margin smooth, with tiny setae, posteroventral corner subquadrate, ventral margin without robust setae. Uropod 1 not sexually dimorphic, peduncle with 17 or 18 robust setae, peduncle distolateral robust seta absent; inner ramus subequal in length to outer ramus, with 18 or 19 marginal robust setae; outer ramus with 10 marginal robust setae. Uropod 2 not sexually dimorphic; peduncle with 5 robust setae; inner ramus subequal in length to outer ramus, with 14 marginal robust setae; outer ramus with 6 marginal robust setae. Uropod 3 peduncle with 7 robust setae; ramus subequal in length to peduncle, ramus spatulalike, ramus with 11 marginal robust setae and 4 or 5 apical setae. Telson broader than long, apically incised, dorsal midline entire, with marginal and apical robust setae, with 18 robust setae per lobe.

Male juvenile, paratype, AM P.87933. Gnathopod 1 propodus palm slightly obtuse; dactylus as long as palm. Gnathopod 2 merus without posterodistal lobe on medial surface; propodus with posterodistal palmate lobe; palm transverse, straight.

Female (sexually dimorphic characters). Based on paratype female, AM P.87934. Gnathopod 1 parachelate, posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; posterolateral surface with more than 10 serrate setae. Gnathopod 2 mitten-shaped; basis slightly expanded; ischium and merus without posterodistal lobe on medial surface; posterior margin of propodus with lobe covered in palmate setae; carpus well developed (not enclosed by merus and propodus), posterior lobe present, projecting between merus and propodus; 2.8 × as long as wide; palm obtuse, smooth, lined with serrate setae.

Remarks. The most distinctive difference between B. mariae and B. richardsoni is the shape of the male gnathopod 2 palm. In B. richardsoni the palm forms a broad concave distal margin with a narrow tooth just past the midpoint and a broad proximal margin with a small tooth and a discrete corner. In B. mariae the distal margin is much narrower, the midpalmar tooth is broader and widely rounded with 9 or 10 small robust setae, the broad proximal margin has a shallow ledge with about 11 robust setae. Also gnathopod 1 is parachelate in B. mariae and subchelate in B. richardsoni .

Distribution. New South Wales: Jervis Bay; Narrawallee Beach (current study).