Mallacoota misool Hughes, 2016, sp. nov.

Mallacoota misool sp. nov.

(Figs 1–3)

Type material. Holotype male, 6.3 mm, dissected 4 slides, AM P.97890; paratype 1 female, 7.3 mm, dissected and mounted on 4 slides, AM P.97891. Paratypes: 1 male hyperadult, 8 mm, not dissected, AM P.97892; 27 specimens (3 male, 24 female and juveniles), AM P.97893; Misool Island, West Macleur Gulf, West Papua (1°52' S 130°10'E), 16 December 1973, coll. H. Cogger (K08-12).

Type locality. Misool Island, West Macleur Gulf, West Papua (1°52'S 130°10'E).

Etymology. Named from the type locality as a noun in apposition.

Description. Based on holotype.

Head. Eyes ovate; lateral cephalic lobe broad, truncated, anteroventral margin with notch/slit. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2, with 3 robust setae along posterior margin; article 2 longer than article 3; flagellum articles longer than broad proximally, broader than long distally, with 18–24 articles; accessory flagellum minute, with 3 articles. Antenna 2 peduncular article 2 cone gland not reaching to end of peduncular article 3; article 4 longer than article 5; flagellum with 7 articles. Maxilla 1 inner plate subtriangular, with 3 apical plumose setae. Lower lip outer lobes with 1 pair of ducts , mandibular lobes apically rounded. Mandible accessory setal row well developed with 4 setae; molar well developed, triturative; mandibular palp well developed, 3- articulate; article 1 length 3.1 times as long as broad, 0.9 times article 2; article 2 length 0.9 times article 3, with 2 setae; article 3 rectilinear, long (6 times as long as broad), 1.2 times article 1, with 2 apical setae.

Pereon. Gnathopod 1 coxa anterior margin weakly concave, anteroventral corner produced, rounded; carpus 1.8 times as long as broad, shorter than propodus; propodus medial surface with comb, palm subacute, straight, entire, defined by posterodistal corner, with 4 robust setae. Gnathopod 2 subchelate; basis slender, anterodistal corner with well developed lobe; ischium anterior margin with pair of well developed lobes; merus distoventrally acutely produced; carpus compressed, lobate, projecting between merus and propodus; propodus massive, without medial setal bunch, palm near transverse, 0.4 times length of propodus, subrectangular distomedial shelf with 7 robust setae, palmar margin defined by corner with 2 large subacute teeth, without robust setae, subpalmar surface smooth; dactylus without posteroproximal shelf, posterior margin with distal tooth, apically subacute, closing along palm. Pereopods 5–7 basis expanded, posterior margin serrate; merus and carpus not broadened; carpus and propodus with long, slender setae along margins; propodus not expanded posterodistally; dactylar ungues simple. Pereonite 7 without carina.

Pleon. Epimera 1–3 posteroventral corner with small acute tooth. Urosomite 1 bicarinate, subtriangular. Urosomites 2–3 without carina. Uropod 1 peduncle with 1 basofacial seta; outer ramus shorter than inner ramus. Uropod 2 outer ramus shorter than inner ramus. Uropod 3 rami distally truncated, with long and short apical robust setae; inner ramus long (length 2.5 times breadth), subequal to outer ramus; outer ramus longer than peduncle. Telson deeply cleft, longer than broad, tapering distally, with short inner and long outer apical cusps, apical conical extension reaching one third along longest seta, each lobe with 2 long and 1 short apical robust setae.

Female (sexually dimorphic characters), based on paratype female, AM P. 97891. Gnathopod 2 carpus short, not lobate, enclosed by merus and propodus; propodus linear, with slender setae along margins, palm without distomedial shelf, palmar margin minutely serrate, entire, defined by posteroventral corner, with 4 posterodistal robust setae; dactylus margins smooth.

Remarks. Mallacoota misool sp. nov. is closely aligned with M. chandaniae from tropical northern Australia and Nansha Island, South China Sea (see Ren, 2012 as M. subcarinata). Within the genus Mallacoota these two species are distinct, with a near transverse palm on the male gnathopod 2 which is defined by two large teeth. Mallacoota misool sp. nov. can be readily separated by the absence of a setal fringe on the gnathopod 2 propodus palm, where M. chandaniae has a dense setal bunch. In M. misool sp. nov. the male gnathopod 2 dactylus the hump on the posterior margin is distally placed while in M. chandaniae the hump is proximal

Distribution. West Papua: Misool Island (current study).