Maeridae from the Indo-Pacific: Elasmopus, Leeuwinella gen. nov., Maeropsis, Pseudelasmopus and Quadrimaera (Amphipoda: Crustacea) Author Hughes, Lauren E. text Zootaxa 2015 4059 2 201 256 journal article 39226 10.11646/zootaxa.4059.2.1 7dbcc655-553b-4d35-8562-1a98c4555b89 1175-5326 232164 F9ED6784-D8C0-409E-9E4F-73879B265BC4 Leeuwinella mistakensis gen. et sp. nov. ( Figs 19–21 ) Type material. Holotype : female, 5.5 mm , dissected, 4 slide, AM P.92754, Vancouver Peninsular, near Mistaken Island , King George Sound, Western Australia , 35°4'S , 117°56'E , 6 m , seagrass, 13 December 1983 , coll. R.T. Springthorpe WA 121. Paratypes : 9 females , AM P.92755, Vancouver Peninsular, near Mistaken Island , King George Sound, 35°4'S , 117°56'E , 6 m , seagrass, 13 December 1983 , coll. R.T. Springthorpe, WA 121. Type locality. Vancouver Peninsular, near Mistaken Island , King George Sound, Western Australia , Indian Ocean, 35°4'S , 117°56'E . Etymology. Named from the type locality. Description. Of holotype female, 5.5 mm , AM P.92754. Head. Eyes ovate; lateral cephalic lobe broad, truncated, anteroventral margin with notch, corner acute. Antenna 1 longer than antenna 2; peduncular article 1 shorter than article 2, with 1 robust setae on posterodistal margin; peduncular article 2 longer than article 3; flagellum articles longer than broad, with 21 articles; accessory flagellum minute, 3-articulate. Antenna 2 peduncular article 2 cone gland not reaching end of peduncular article 3; peduncular article 4 subequal to article 5; flagellum with 9 articles. Mandible incisor cuspidate; accessory setal row with 3 setae; molar well-developed, triturative; palp well-developed, 3-articulate; article 1 twice as long as broad, shorter than article 2; article 2 longer than article 3 with many slender setae; article 3 strongly falcate, anterodistal margin concave, 3 as long as broad, longer than article 1, with apical setae and a comb of short robust setae along anterodistal margin. Lower lip inner lobes present, outer lobes without ducts, mandibular lobes apically acute. Maxilla 1 inner plate subquadrate, with 3 apical plumose setae. Maxilliped palp propodus with small distomedial flap. Pereon. Gnathopod 1 coxa anterior margin concave, anteroventral corner produced, acute, posteroventral margin with notch; merus without posterodistal tooth; carpus 1.9 as long as broad, subequal to propodus, with long slender setae on posterior margin; propodus medial surface setal comb present, palm subacute, convex, entire, lined defined by posterodistal corner with 2 robust setae. Gnathopod 2 ? sexually dimorphic; subchelate; basis slender, anterodistal corner subquadrate; merus with subquadrate distoventral corner; carpus rectilinear, length 1.9 breadth; propodus subovate to rectilinear, palm acute, near straight, palm weakly defined without corner or robust setae; dactylus apically subacute, closing along and reaching end of palm. Pereopod 4 coxa posterodistal lobe well developed. Pereopods 5–7 basis weakly expanded, posterior margin serrate; merus and carpus not broadened; dactylar ungues simple. Pereopod 5 basis posterior margin straight. Pereopod 6 basis posterior margin sinusoidal. Pereopod 7 posterior margin weakly sinusoidal. Pereonite 7 with single dorsal carina. Pleon. Pleonites 1–3 with single dorsal carina. Epimera 1–3 posterodistal corner with acute tooth. Epimeron 1 posterior and ventral margins smooth. Epimeron 2 posterior margin smooth, ventral margin distally serrate. Epimeron 3 posterior and ventral margins distally serrate. Urosomites 1–2 without carina, without dorsal setae. Uropod 1 peduncle with 1 basofacial seta, inner ramus slightly longer than outer ramus, 0.9 peduncle length. Uropod 2 inner ramus subequal to outer ramus. Uropod 3 inner ramus length 2.1 breadth, 0.5 outer ramus length; outer ramus1.8 peduncle length, distally truncated, apical robust setae short. Telson as long as broad, moderately cleft (80%), lobes tapering distally (outer margin straight and inner margins angled), each lobe with 2 short apical robust setae. FIGURE 19. Elasmopus souillacensis Appadoo & Myers, 2006 , female 5.5 mm, AM P.98051, Fishing Rock landing, Raoul Island, Kermadec Islands, New Zealand, scales 0.1 mm. FIGURE 20. Leeuwinella mistakensis gen. et sp. nov. holotype female, 5.5 mm, AM P. 92754, Vancouver Peninsular, near Mistaken Island, King George Sound, Western Australia. Remarks. See remarks for genus. The falcate mandibular palp in Leeuwinella mistakensis gen. et. sp. nov. is also present in Elasmopus , but the presence of dorsal carinae is rare within the genus. Four Elasmopus species, E. japonicas Stephensen, 1932 , E. neglectus Chilton, 1915 , E. shepherdi Hughes & Lowry, 2011 and E. woodjonesi Hughes& Lowry, 2011 have a unicarinate urosomite 1 only, whereas urosomite 1 is smooth in E.mistakensis sp. nov. Within Maeridae , only two other species have unicarinate pleonites. Hoho carteta J.L. Barnard, 1972a and Mallacoota unidentata Ren, 1998 have pleonites 1 and 2 only with a single carina. The strongly falcate mandibular palp, single carinae on pereonite 7 and pleonites 1 and 3 along with the serrate distal margins of epimera 2 and 3 make Leeuwinella mistakensis gen. et. sp. nov. distinctive among Australian maerid species. Distribution. Indian Ocean: Australia : Western Australia : Vancouver Peninsular (current study).