Hoho tricarinata, Hughes, 2011

HUGHES, L. E., 2011, New species of Hoho, Mallacoota and Parelasmopus (Maeridae: Amphipoda) from Australian waters, Zootaxa 2955 (1), pp. 1-79 : 26-29

Hoho tricarinata sp. nov.

(Figs 16–18)

Type material. Holotype: male, 9.1 mm, dissected,4 slides, AM P.85202 . Paratypes: 17 specimens, AM P.79361 Rocks near Migo Island, Port Harding , Torbay Bay , Western Australia (35º04'S 117º39'E), 6–7 m, small branched alga with compound tunicate on underside of branches, 15 December 1983, coll. R. T. Springthorpe and J.K. Lowry (WA 152) .

Additional material examined. Western Australia. 1 male, 7.5 mm, dissected, 3 slides, AM P.79367, off Possession Point, King George Sound (35º02”30’S 117º55’E), 7 m, mixed sponges and algae, 14 December 1983, coll. J.K. Lowry (WA 135); 20+ specimens, AM P.79395 Red Bluff, Kalbarri (27º42'S 114º09'E), 3–4 m, rocky shore, mixed algae, sediment, 10 January 1984, coll. R. T . Springthorpe (WA 474) ; 4 males, 2 females, MV J57015 , point at north end of Little Beach, Two Peoples Bay (34º58”12’S 118º10”48’E), 5 m, 18 April 1986, ( SWA 78 ) ; 10 specimens, MV J62169 , north end of Little Beach, Two Peoples Bay , (34°58“24’S 118°11”42’E), depth unknown, 5 April 1984, coll. H. Lew Ton and G.C.B Poore ( SWA 10 ) ; 1 male, MV J57202 , reef 500 m offshore, Port Gregory (28º12”00’S 114º15”00’E), 1 m, 28 April 1986 ( SWA 102 ) ; 3 males, 7 females, MV J57200 , 2 km off Mullaloo, North Lumps (31º47”18’S 115º42”48’E), 6 m, 2 May 1986, ( SWA 111 ) ; 2 males, 4 females, MV J57016 , west end of Michaelmas Island (35º02”48’S 118º01”24’E), 15 m, 17 April 1986 ( SWA 63 ) ; 1 female, MV J62170 , northeastern end of Vancouver Peninsula (35º03”24’S 117º56”12’E), 3 m, 8 April 1984 ( SWA 22 ) .

Type locality. Migo Island, Port Harding, Torbay Bay , Western Australia (35º04'S 117º39'E) .

Etymology. The name is in reference to the dorsal tricarination of the pleonites.

Description. Based on holotype male, 9.1 mm, AM P.85202.

Head. Eyes ovate; lateral cephalic lobe broad, truncated, anteroventral margin with notch/slit. Antenna 1 longer than antenna 2; peduncular article 1 shorter than article 2, with 5 robust setae along posterior margin; article 2 longer than article 3; flagellum articles as long as broad, with 34+ articles; accessory flagellum short, with 4 articles. Antenna 2 peduncular article 2 cone gland reaching at least to end of peduncular article 3; article 4 longer than article 5; flagellum with 13 articles. Lower lip outer lobes with two pair of ducts, mandibular lobes apically rounded. Mandible accessory setal row well developed with 3 setae; molar well developed, triturative; mandibular palp vestigial, 1-articulate.

Pereon. Gnathopod 1 coxa anterior margin straight, anteroventral corner slightly produced, rounded; 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 2 robust setae. Gnathopod 2 subchelate; basis broad; with single well developed anterodistal lobe; merus with rounded distoventral corner; carpus compressed, lobate, projecting between merus and propodus; propodus massive, with sparse setal bunches along posterior margin, palm straight, sculptured, one third to half length of propodus, subtriangular distomedial shelf, with 6 robust setae on shelf, palmar margin with 2 subacute teeth, without robust setae, defined by posteroventral tooth, without posterodistal robust setae, subpalmar surface with long seam; dactylus with posteroproximal shelf, apically subacute, closing along palm. Pereopod 4 coxa posteroventral lobe well developed, with rounded posteromedial corner. Pereopods 5–7 basis slightly 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. Pereopod 5 basis posterior margin straight, posteroventral corner broadly rounded. Pereopod 6 basis posterior margin subsigmoidal, posteroventral corner broadly rounded. Pereopod 7 basis posterior margin straight, posteroventral corner broadly rounded. Pereonite 7 without carina.

Pleon. Pleonites 1–2 tricarinate. Pleonite 3 without carina. Epimera 1–2 posteroventral corner with small acute tooth. Epimeron 3 ventral margin smooth, posteroventral margin smooth, posteroventral corner with strongly produced 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 apical robust setae short; inner ramus long (length twice the breadth), subequal in length to outer ramus; outer ramus longer than peduncle. Telson deeply cleft, as long as broad, tapering distally, with short inner and long outer apical cusps, apical conical extension reaching at least halfway along longest seta, each lobe with 4 long apical robust setae.

and palm defining tooth, while H. carteta has a smooth palm margin and H. marilla has only a distal tooth. Pleonites 1 to 2 are bicarinate in H. wittecarra sp. nov., and tricarinate in Hoho tricarinta sp. nov., which further separates the later from other Hoho species. The presence of a midmedial subacute tooth on the dactylus of gnathopod 2 is only known for the adult male of H. tricarinata sp. nov.

Hoho tricarinata sp. nov. is the first species described in the Maeridae to have a tricarinate formation on the pleonites. Unicarinate ( Hoho , Elasmopus, Sauradocus ), bicarinate ( Hoho , Mallacoota ) or serrate ( Ceradocus ) pleonite forms, also occur within this family.

Distribution. Western Australia: Torbay Bay; King George Sound; Michaelmas Island; Hopetoun; Kalbarri; Two Peoples Bay; Port Gregory; Mullaloo; Vancouver Penninsula (current study).