Zeaphoxus, Taylor & Peart, 2023

Taylor, Joanne & Peart, Rachael A., 2023, A New Genus and Five New Species of Phoxocephalidae (Crustacea: Amphipoda) from the Eastern Tasman Sea, the Otago Shelf, and The Snares, New Zealand, Records of the Australian Museum (Rec. Aust. Mus.) 75 (4), pp. 567-600 : 591

Zeaphoxus gen. nov.

urn:lsid:zoobank.org:act:DDD41A3A-5207-42E5-869A-0A05BAB40504

Diagnosis. Rostrum fully developed, unconstricted. Eyes present.Antennae 1–2, flagella unreduced in female. Article 2 of antenna 1 ordinary, ventral setae widely spread, in middle.Antenna 1 peduncle article 2 not or weakly ensiform; article 3 with 2 setules; facial robust setae on article 4 primarily in 1 row; article 5 ordinary. Prebuccal appendages not extended forward, rounded, massive, not strongly distinct, epistome dominant. Right mandibular incisor with 3 teeth; molar not triturative, small, pillow shaped, with 3 semi-articulate robust setae, 1 of these enlarged, with patch of fine setae; palpar hump medium; right lacinia mobilis bifid, broad; mandibular palp thin, article 1 short, article 2 without outer setae, apex of article 3 oblique, all distal setae confined to apex. Lower lip with salivary cones. Maxilla 1 palp 2-articulate, inner plate with 4 setae, outer plate with 11 robust setae, 1 robust seta especially thickened. Maxilla 2 ordinarily setose, outer plate scarcely enlarged. Maxilliped outer plates thin, elongate, spinose, and setose, apex of palp article 3 scarcely protuberant, dactylus elongate, apical nail indistinct, mostly immersed, short. Gnathopods small, weakly diverse, propodus of gnathopod 2 distinctly larger than on gnathopod 1; carpus of gnathopod 1 free, of gnathopod 2 very short and almost cryptic, palms acute, propodi ordinary, almond shaped, poorly setose anteriorly. Pereopods 3–4 carpus with posteroproximal setae, all posterior robust setae on propodus thin and stiff, midapical robust setae present. Pereopod 5 basis broad, tapering, Pereopods 5–6 basis not setose posteriorly, merus-carpus medium to narrow. Pereopod 7 basis without ventral and facial setae, with only 1 facial ridge, ischium slightly enlarged and strongly setose anteroventrally, merus not lobed. Epimera 1–2 lacking elongate posterior setae, with midfacial setae below ventral facial ridge. Epimeron 3 setose facially, smooth posteriorly. Urosomite 1 generally naked except for sparse apicoventral setae or robust setae near base of uropod 1. Urosomite 3 without dorsal hook or special process. Uropod 1 peduncle without apicoventral enlarged robust setae, with special enlarged apical robust seta, with basoventral setae, with dorsolateral robust setae narrowly spread, very weak, confined apically, medial robust setae widely spread. Uropod 1 outer ramus ordinary, inner ramus with marginal robust setae in 1 row, no rami of uropods 1–2 continuously spinose to apex. Uropod 2 inner ramus ordinary. Uropod 3 peduncle lacking extra slender or robust setae, article 2 of outer ramus short, with 2 medium apical setae. Telson with pair of midlateral or dorsal setules on each side, 2 apical robust setae on each lobe, without special dorsal and lateral slender and robust setae. Five pairs of gills.

Sexual dimorphism. Male not known.

Type species. Zeaphoxus zealandicus sp. nov.

Etymology. From New Zealand and “phoxus” a common root of genera in Phoxocephalidae . Gender masculine.

Remarks. Zeaphoxus gen. nov. and two new species, Zeaphoxus senecio sp. nov. from the Tasman Sea and The Snares, 7–507 m and Zeaphoxus zealandicus sp. nov. from the Otago Shelf, 65 m are recognized. These new species could not definitively be keyed to either a subfamily or genus according to Barnard & Karaman (1991) due in part to the recombination of characters including: structure of the molar (small, pillow shaped, and non-trituritive), length of article 2 of antennae 1 (elongate) and gnathopods 1–2 diverse in size with gnathopod 2 obviously larger than gnathopod 1. The preliminary morphological phylogeny of Taylor (2003) elucidated that they share a combination of traits with species belonging to the genera Eyakia , Leongathus , and Mesophoxus , including antenna 1, peduncle article 2 with ventral setae situated on middle, right mandibular incisor with 3 teeth and pereopod 5 of broad form but tapering distally. Taylor (2006) was faced with a similar dilemma when trying to place a new species collected from the Tasman Sea. The partly triturate molar but narrow basis of pereopod 5 in part informed the decision to redescribe the genus Leongathus to accommodate Leongathus alannah Taylor, 2006 rather than erecting another monotypic genus. Although these authors note Zeaphoxus gen. nov. has morphological affinities with both Eyakia and Mesophoxus from North Pacific waters, and with species of Leongathus , known from the Tasman Sea and southern Australia, the decision to establish a new genus instead of making an emended diagnosis of an existing genus is taken in this instance.

Key to the world species of Zeaphoxus

1 Dorsolateral margin of uropod 1 peduncle with 2 robust setae; dorsal margin of uropod 2 peduncle with short apical robust setae and elongate proximal setae. Proximal branch of right lacinia mobilis not longer than distal branch ........................................ ........................................... [ New Zealand, Otago Shelf; 65 m] .. Zeaphoxus zealandicus sp. nov.

—— Dorsolateral margin of uropod 1 peduncle with 5 or 6 robust setae; dorsal margin of uropod 2 peduncle with all medium similar robust setae. Proximal branch of right lacinia mobilis much longer than distal branch ................................................. ......................................[Tasman Sea & The Snares; 7–507 m] ...... Zeaphoxus senecio sp. nov.