Acheronia pegasus Lowry, 1984

Lowry, J. K. & Stoddart, H. E., 2012, The Pachynidae fam. nov. (Crustacea: Amphipoda: Lysianassoidea) 3246, Zootaxa 3246 (1), pp. 1-69 : 7-8

Acheronia pegasus Lowry, 1984

( Figs 1 , 2 )

Acheronia pegasus Lowry, 1984: 93 , figs 34–36. ― Barnard & Karaman, 1991: 454. ― Hicks et al., 1991: 14. ― Springthorpe & Lowry, 1994: 28.

Description. Head lateral cephalic lobe large, broadly rounded; ventral margin curved. Antenna 1 peduncular article 1 without posterodistal spine; accessory flagellum 2-articulate, article 1 short; flagellum without callynophore [in specimen of unknown sex]. Mandible lacinia mobilis absent; lamina dentata absent; accessory setal row present, not on raised setose ridge; molar absent; palp attached midway; palp article 2 slender, longer than article 3; article 3 with subparallel margins. Maxilla 1 outer plate with 7 setal-teeth in 4/3 arrangement, setal-teeth smooth; palp well developed, 2-articulate, with apical slender setae. Maxilliped inner plate small; outer plate medium size; palp 4-articulate, article 4 large. Gnathopod 1 subchelate; ischium smaller than propodus, not swollen posteroproximally; carpus extremely compressed; propodus length about 1.5 × breadth, posterior margin extremely reduced, palm with produced corner, corner of palm without robust seta; dactylus reaching to corner of palm. Gnathopod 2 palm large, extremely acute. Pereonite 4 without dorsal spines. Pereonite 5 without dorsal spines. Pereopod 5 merus with posteroproximal shoulder. Pereopod 6 basis with posteroventral lobe weakly produced; merus broader than long, with posteroproximal shoulder. Pereopod 7 basis subovate with posterior margin smooth. Epimeron 3 posterior margin without projections, posteroventral corner broadly rounded. Uropod 3 biramous, inner ramus extending less than halfway along outer ramus. Telson shorter than broad, entire.

Remarks. The original description of A. pegasus recorded the maxilla 1 outer plate setal-teeth arrangement as 3/3. We have re-examined the type material and find that the arrangement is really 4/3, with two of the outer-row setal-teeth slender and closely apposed.

Distribution. Stewart Island, New Zealand, western South Pacific Ocean; 42 m depth.

Figures

FIGURE 1. Acheronia pegasus Lowry, 1984. Paratype, 5 mm, AM P.31999, Stewart Island, New Zealand.

FIGURE 2. Acheronia pegasus Lowry, 1984. Paratype, 5 mm, AM P.31999, Stewart Island, New Zealand. Scales represent 0.1 mm.