Ambicholestes (Ambicholestes) poorei, Just, 1998

Just, Jean, 1998, Siphonoecetinae (Crustacea: Amphipoda: Ischyroceridae) 7: Australian Concholestids, Ambicholestes n. gen., with a Description of Six New Species, and a New, Restricted Diagnosis for Caribboecetes Just, 1983, Records of the Australian Museum 50 (1), pp. 27-54 : 38-42

Ambicholestes (Ambicholestes) poorei n.sp.

Figs 9-11

Material examined. HOLOTYPE: male, 2.4 mm, Bass Strait, 40006'S 143°16'E, 187 m, fine sand with some mud and silt, grab, G.C.B. Poore, 11 October 1980, Stn BSS 101, NMV J9544 . PARATYPE: Bass Strait, 4000TS 143°12'E ,

229 m, muddy sand, grab, G.C.B. Poore, 11 October 1980, Stn BSS 105, NMV J9545 (1 male) .

Diagnosis. Rostrum absent. Midanterior margin of cephalon forming a broadly rounded lobe. Antenna 1 peduncle article 1 and antenna 2 distal to peduncle article 2 with cover of microsetules. Midcephalic lobe and pleon with cover of microsetules.

Further description. Antenna 1 peduncular article 1 without robust setae, with ventral cover of microsetules. Antenna 2 peduncular article 3 with 1 midmedial robust seta, with dorsal to medial cover of microsetules; ventroapical projection of article 2 about as long as wide, rounded triangular, with a few long apical setae.

Coxal plate 4 barely longer than wide at base, plate 3 ca. 50% longer than wide. Coxal plates 5 and 6 posterior lobe with ventral part triangular, apex blunt, dorsal part rounded, not upward turned; this configuration being more pronounced in plate 6. Pleonal side plates 1 and 2 with weak posterior angle and 2 small insinuations each with a

40 Records of the Australian Museum (1998) Vol. 50 short seta below ordinary, wide sinus.

Mouthparts normal. Mandibular palp reaching to tip of incisor, with lose lateral and dorsal cover of microsetules.

Pereopod 1 article 6 with posterodistal tooth and 2 posterior robust setae; article 5 without ventrodistal robust seta. Pereopod 2 article 6 with 4 posterior robust setae; article 2 anterior margin convex, with a few long and short setae. Pereopod 7 article 2 with lateral setal row unusually short, composed of 2 setae only.

Uropod 1 outerramus about 3 Ih times longerthan broad with up to 6 lateral robust setae; inner ramus ca. 113 length of outer ramus, with rounded medioapical projection and

lateral robust setae only. Urosomites 1 and 2 free. Urosomite 3 and telson fused dorsally.

Size. Largest male: 2.4 mm; female not known.

Colour. Not known.

Biology. On muddy-silty sand.

Distribution. Western Bass Strait; 187-229 m depth.

Etymology. The species is named for Dr Gary Poore (Museum ofVictoria) for his role in the exploration of the Bass Strait benthic fauna.

Ambicholestes (Ambicholestes) sp. A

Fig. 12

Material examined. Male, 2.3 mm, Bass Strait, 38°32'S 142°28'E, 52 m, medium sand, G.C.B. Poore, 20 November 1981, Stn BSS 187, NMV J9546 .

The single specimen, which has lost both pairs of antennae, is very similar to A. (A.) poorei described above. It shares with that species all characteristics except the following: coxal plate 3 twice as long as wide at base; plate 4 50% longer than wide; coxal plates 5 and 6 with posterior lobe roundedventrally, withdorsalpartupwardturned,rounded; pereopod 7 article 2 with row of 6 mediolateral setae.

Ambicholestes (A.) sp. A is probably distinct from but closely related to A. poorei . However, more material of both is needed before this question can be adequately addressed.

Figures

Fig. 12. Ambicholestes (Ambicholestes) sp. A, NMV J9546. c, cephalon, dorsal and lateral view; co, coxal plate (3-6).