Acutocoxae, RAUSCHERT, 2017

Ashford, Oliver S., Horton, Tammy, Roterman, Christopher N., Thurston, Michael H., Griffiths, Huw J. & Brandt, Angelika, 2020, A new Southern Ocean species in the remarkable and rare amphipod family Podosiridae (Crustacea: Amphipoda) questions existing systematic hypotheses, Zoological Journal of the Linnean Society 190, pp. 613-631 : 620-621

GENUS ACUTOCOXAE RAUSCHERT, 2017 (AMENDED)

Type species: Acutocoxae weddellensis Rauschert, 2017 .

Diagnosis

Bodyslender,dorsoventrallyflattened, carinatedorsally and laterally. Rostrum moderate; lateral cephalic lobe strongly produced, acute. Eyes present. Antenna 1 much longer than body, peduncle article 1 much longer than the head, article 2 longer than article 1, article 3 short, accessory flagellum absent. Antenna 2 slender. Labrum weakly bilobed. Mandibular molar a toothed flap, incisor process multidentate, lacinia mobilis on left mandible only (in A. ogilvieae ), as broad as incisor; palp uniarticulate. Maxilla 1 inner plate small with a single robust terminal seta, outer plate with large terminal robust setae. Maxilla 2 inner plate short, shorter than outer. Maxilliped basal article elongate, reflexed posteriorly; inner plates very small, fused or not; outer plates absent; palp very elongate, strongly raptorial, 4-articulate, dactylus recurved, longer than article 3, minutely serrate.

Coxae 1–2 short, with single acute antero- or ventrolaterally directed processes. Coxae 3–4 short, with two acute antero- and posterolaterally directed processes. Coxae 5–7 short, with single acute posterolaterally directed processes. Gnathopod 2 larger than gnathopod 1, subchelate. Pereopods 3–7 strongly prehensile, basis linear, not lobate. Epimeral plate 3 subquadrate. Urosomite 1 longer than 2 and 3 combined, without dorsal teeth. Uropods 1–3 peduncles much longer than rami. Uropod 3 uniramous. Telson entire, suboval, without setae.

Remarks

Specimens of the new species exhibit the slender, dorsoventrally flattened body, moderate rostrum, lack of accessory flagellum, extended, raptorial maxilliped, acuminate coxae, elongate urosomite 1 and entire telson that are seen in the genus Podosirus . However, the genus Acutocoxae differs from Podosirus in the strongly produced lateral cephalic lobes, presence of eyes, ratio of antenna 1 articles, elongate peduncles of uropods 1–3 and uniramous uropod 3.

A revised diagnosis of the genus Acutocoxae Rauschert, 2017 is provided. Rauschert (2017) indicated that A. weddellensis possesses a rudimentary accessory flagellum. Our examination of the type material reveals a group of small setae, but no accessory flagellum. No accessory flagellum was found in our new species. Rauschert (2017) provided an illustration of the mandibular molar, which he described as having a ‘strong elevation for grinding’. We have been unable to examine this, because both mandibles are missing from the type material. This is different from the toothed flap molar found in our new species. Eyes are prominent, hemispherical, and similar to those of some species in the family Melphidippidae Stebbing, 1899 .

ACUTOCOXAE OGILVIEAE HORTON, ASHFORD &