Hoho kangarooensis, Hughes, 2011

HUGHES, L. E., 2011, New species of Hoho, Mallacoota and Parelasmopus (Maeridae: Amphipoda) from Australian waters, Zootaxa 2955 (1), pp. 1-79 : 14-17

Hoho kangarooensis sp. nov.

( Figs 8 , 9)

Type material. Holotype: male, 9.0 mm, dissected,4 slides, AM P.85190 . Paratypes: 1 female, 7.4 mm, dissected, 1 slide, AM P.85191; 1 male, AM P.85192, Cape du Couedic, Kangaroo Island , South Australia (36°04'S 136°42'E), beach washings from algal holdfast, 4 March 1979, coll. P. Hutchings and A. Bulter ( SA 58 ) .

Type locality. Cape du Couedic, Kangaroo Island , South Australia (36°04'S 136°42'E) .

Etymology. Named for the type locality.

Description. Based on holotype, male, 9.0 mm, AM P.85190.

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, without robust setae along posterior margin; article 2 longer than article 3; flagellum articles longer than broad, with 26+ articles; accessory flagellum minute, with 3 articles. Antenna 2 peduncular article 2 cone gland reaching at least to end of peduncular article 3; article 4 subequal in length to article 5; flagellum with 10 articles. Lower lip outer lobes with two pair of ducts, mandibular lobes apically subacute. Mandible accessory setal row well developed with 3 setae; molar well developed, triturative; mandibular palp reduced, 1-articulate; article 1 about 3 times as long as broad.

Pereon. Gnathopod 1 coxa anterior margin straight, anteroventral corner slightly produced, rounded; merus without posterodistal tooth; carpus about twice as long as broad, subequal in length to propodus; propodus medial surface with comb, palm acute, convex, entire, defined by posterodistal corner, with 7 robust setae. Gnathopod 2 subchelate; basis slender, anterodistal corner subquadrate; merus without distoventral corner; carpus compressed, lobate, projecting between merus and propodus; propodus expanded, with slender medial setal bunch, palm acute, straight, smooth, subtriangular distomedial shelf, with 2 robust setae on shelf, palmar margin with 1 subquadrate tooth, without posterodistal robust setae, subpalmar surface smooth; dactylus with posteroproximal shelf, apically subacute, closing along palm. Pereopod 4 coxa posteroventral lobe well developed, with rounded posteromedial corner. Pereopods 5–7 basis expanded, posterior margin minutely castelloserrate, without long slender setae; merus and carpus not broadened; carpus and propodus without long slender setae along posterior margin; propodus not expanded posterodistally; dactylar ungues simple. Pereopods 5–6 basis posterior margin straight, posteroventral corner broadly rounded. Pereopod 7 basis posterior margin convex, posteroventral corner broadly rounded. Pereonite 7 without carina.

Pleon. Pleonites 1–3 without carina. 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 slightly shorter than inner ramus. Uropod 2 outer ramus slightly shorter than inner ramus. Uropod 3 rami distally truncated, apical robust setae short; inner ramus short (length 1.5 times breadth), shorter than outer ramus; outer ramus longer than peduncle. Telson deeply cleft, broader than long, tapering distally, apical margins concave, with short inner and long outer apical cusps, apical conical extension reaching scarcely one third along longest seta, each lobe with 2 long and 1 short apical robust setae.

Female (sexually dimorphic characters), based on AM P.85191. Gnathopod 2 carpus short, not lobate, enclosed by merus and propodus; propodus linear, with slender setae along posterior margin, palm about one third length of propodus, without distomedial shelf, palmar without teeth, margin lined with a row of robust setae, defined by posteroventral corner, with 4 posterodistal robust setae; dactylus without posteroproximal shelf.

Remarks. The large subquadrate tooth on the male gnathopod 2 palm distinguishes this species from all other Hoho .

Curiously, three species from three closely related maerid genera have this distinctive gnathopod 2, with large square tooth and palm with dense setal bunch, H. kangarooensis sp. nov., Mallacoota schellenbergi Ledoyer, 1984 and Elasmopus carteri Hughes & Lowry, 2011 , all of which occur in Australia.

Distribution. Australia. South Australia: Kangaroo Island (current study).

Figures

FIGURE 8. Hoho kangarooensis sp. nov. holotype, 9.0 mm, AM P.85190, Kangaroo Island, South Australia.