Zeaphoxus senecio, 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 : 592-595

Zeaphoxus senecio sp. nov.

urn:lsid:zoobank.org:act:794A6130-C392-432B-8C6F-8FD6B7763841

Figs 17–19

Holotype: NIWA 115621 , female “d”, 12.58 mm, Senecio Pool, The Snares, 48°07'S 166°36'E, among deposits of terrestrial plant detritus, 7 m, SA3487 , G. D. Fenwick, 6 January 1977 . Paratype: NIWA 115622 , juvenile “e”, 5.48 mm, collected together with holotype .

Other material examined. AM P39545 , juvenile “f1”, 3.82 mm plus 9 specimens, eastern Tasman Sea , 41°58.5'S 170°28.1'E, 507 m, P. K. Probert on RV Tangaroa, cruise 1131 , Station Q723, 4 March 1982 ; NIWA 115633 , 1 specimen, eastern Tasman Sea , 41°15.102'S 170°37.5'E, 560 m, P. K. Probert on RV Tangaroa, cruise 1131 , Station Q700, 23 February 1982 ; NIWA 115634 , 2 specimens, eastern Tasman Sea , 42°25.5'S 171°05.502'E, 37 m, P. K. Probert on RV Tangaroa, cruise 1131 , Station Q725, 4 March 1982 ; AM P25803 , 3 specimens, Otago Shelf , New Zealand, 45°53'S 170°51'E, sandy gravel, bottom, 93 m, P. K. Probert on RV Munida , MU75 /54, 19 February 1975 .

Etymology. Named for the type locality; used as a noun in apposition.

Diagnosis. Eyes present. Head without constriction in dorsal view. Antenna 1 peduncular article 1 ventral apex not ensiform, peduncle article 2 shortened. Antenna 2 peduncle article 3 with robust setae, article 4 shortened with facial robust setae. Right mandible lacinia mobilis bifid, proximal branch much longer than distal branch. Maxilla 1 inner plate moderately large, outer plate with 11 multicuspidate robust setae. Maxilliped palp article 3 weakly produced. Posteroventral corner of coxae 1–3 without tooth. Gnathopods 1–2 carpus not cryptic. Gnathopod 2 similar sized to gnathopod 1, propodus with 1 robust seta near palmar corner. Pereopods 3–4 carpus setae placed near anterodistal margin. Robust setae forming dominant posterior element on pereopods 3–4 carpus. Pereopod 5 basis broad. Pereopod 6 basis anterior margin without setae, posterodistal corner not produced to form a lobe. Pereopod 7 merus, carpus, and propodus narrow; dactylus long. Urosome without basoventral setae. Epimera 1–2 without facial setae. Uropods 1–2 rami never fully spinose, rami with articulate enlarged apical nails, lacking accessory nails. Uropod 1 peduncle with 5–6 robust setae on dorsolateral margin. Uropod 2 peduncle only with robust setae. Uropod 3 outer ramus article 2 with 2 long apical setae; inner ramus medium length, about 0.5 × the length of outer. Telson deeply cleft, apically with 1 robust seta per lobe, marginally without setae on each side, without lateral robust setae.

Description. FEMALE, based on NIWA 115621, holotype, female “d”, 12.58 mm.

Head: Eyes large, largely occluded with pigment. Head about 0.20 × total body length, greatest width about 0.75 × length; rostrum not constricted, broad, reaching middle of article 2 on antenna 1. Antenna 1 peduncle article 1 1.7 × as long as wide, about half as wide as article 2, ventral margin with about 10 setules, weakly produced dorsal apex with 3 setae; article 2 about half as long as article 1, with ventral horseshoe cycle arc of 12 setae; primary flagellum 13-articulate, 0.7 × as long as peduncle, lacking large aesthetascs; accessory flagellum 11-articulate. Antenna 2 peduncle article 4 main setal formula = 2-6-4, dorsal margin with notch with 2 setae and 1 robust setae, ventral margin with 5 groups of 2–4 elongate to medium setae, 1 distoventral elongate robust setae; article 5 almost 0.8 × as long as article 4, facial robust setae formula = 3, ventral margin with 6 sets of 1 elongate seta each, 1 distoventral medium robust setae; flagellum about as long as articles 4–5 of peduncle combined, 14 articulate.

Mouthparts: Mandibles with small palpar hump; right incisor with 3 teeth; left incisor with 3 weak humps in 2 branches; right lacinia mobilis bifid, distal branch flabellate, shorter than proximal, proximal branch simple, pointed; left lacinia mobilis with 4 teeth; right accessory setal row with 10 multicuspidate stout setae, left with 11; molar bulbous, weak, with 1 large curved robust seta and 2 much smaller simple robust setae, no disjunct robust setae, each molar with patch of fine seta; palp article 1 short, article 2 with 3 elongate inner setae and 1 other short inner seta and no outer setae, article 3 about 1.1 × as long as article 2, oblique apex with 10 elongate robust setae. Maxilla 1 inner plate medium, with 2 elongate apicomedial pappose setae, 2 apicolateral much shorter setae; palp article 2 with 4 medial marginal robust setae, and 2 apical and 5 submarginal setae. Maxilla 2 plates extending subequally, of diverse breadth, outer with 4 apicolateral setae, inner with 2–3 medial setae. Maxilliped inner plate with 3 large apical robust setae, 3 apicofacial plumose setae and 2 medial setae; outer plate with 14 medial and apical robust setae, 6 apicolateral setae; some setae set into cuspidate recesses; palp article 1 with 3 apicolateral setae, medial margin of article 2 moderately setose, article 3 scarcely produced, with 8 facial setae, 2 lateral setae, article 4 long, with 2 accessory setules, nail short.

Pereon: Coxa 1 not expanded distally, anterior margin almost straight, main ventral setae of coxae 1–4 = 7-8- 12-many, posterior most seta of coxae 1–4 not shortened; anterior and posterior margins of coxa 4 parallel, posterior margin almost vertical, convex, posteroventral margin not bevelled, posterodorsal corner rounded, posterodorsal margin short, concave, width to length ratio of coxa 4 = 9:10. Coxae 5–7 posteroventral setule formula = 5-8-1. Gnathopods 1–2 slightly enlarged, weakly diverse, width ratios of carpus-propodus on gnathopods 1–2 = 12:15 and 23:32, length ratios = 12:21 and 16:37; palmar humps small to medium palms acute, with 1 robust seta defining palm; gnathopods 1–2 carpus medium and short respectively, of gnathopod 1 ovate, posterior margin of 1 flat, of 2 lobate, of gnathopod 2 short, subcryptic, triangular. Pereopods 3–4 similar, facial setae formula on merus = 7 and 5, on carpus = 7 and 6; main robust setae of carpus extending to M.58 on propodus, carpus without posteroproximal robust setae; setal formula of propodus = 5-2 plus mid-distal robust setae acclivity on inner margin of dactyls of pereopods 3–4 large, weak. Pereopods 5–6 merus-carpus narrow, facial robust setal rows poorly developed. Pereopods 5–7 facial ridge formula on basis= 0-1-1, ridge of pereopod 7 long; width ratios of basis, merus, carpus, propodus of pereopod 5 = 22:11:10:6, of pereopod 6 = 33:11:10:5, of pereopod 7 = 40:9:8:4, length ratios of pereopod 5 = 30:13:16:16, of pereopod 6 = 40:22:25:25, of pereopod 7 = 45:10:11:16. Pereopod 7 basis reaching middle of merus. Pereopods 5 and 7 merus without especially elongate posterodistal lobe; medial apex of propodus truncate, uncombed.

Pleon: Epimeron 1, posteroventral corner rounded, posterior margin convex, with setule, anteroventral margin with 9 short setae, ventral margin with 13 elongate setae. Epimeron 2 posteroventral corner quadrate, weakly protuberant, posterior margin almost straight, with setule, facial setae = 2 rows of 8-8, posterior most pair set vertically. Epimeron 3 posteroventral corner subquadrate, posterior margin almost straight, scarcely serrate, 2-setose, uppermost tiny setules, ventral margin with 3 posterior narrowly spread setae, face with obliquely horizontal middle row of 11 setae. Urosomite 1 without ventral robust setae at base of uropod 1. Urosomite 3 not protuberant dorsally. Uropods 1–2 rami with articulate enlarged apical nails, lacking accessory nails. Uropod 1 peduncle with 6 apicolateral robust setae and 7 basofacial setae, medially with 6 marginal slender setae and robust setae becoming thicker distally, outer ramus with 4 lateral and 2 medial robust setae, inner with 1 medial. Uropod 2 peduncle with 10 dorsal robust setae, medially with 1 medium apical robust setae, outer ramus with 3 dorsal robust setae, inner naked. Uropod 3 peduncle with 8 ventral robust setae, dorsally with 1 lateral robust setae, 1 medial robust setae and 2 setules; rami feminine, inner extending to M.67 on article 2 of outer ramus, apex with 2 setae, medial margin with 3 setae, article 2 of outer ramus with 2 elongate setae, medial margin of article 1 with 5 setae, lateral margin with 5 acclivities, setal formula = 2-2-2-2-2-2 (1 short robust seta). Setal formula = 0. Telson short, length to width ratio = 1:1, fully cleft, each apex broad, truncate, acclivity absent, with lateral setule, with long robust seta and setule, midlateral setules diverse.

MALE. Unknown.

JUVENILE, based on NIWA 115622, juvenile “e” 5.48 mm length. As in adult but setae sparser and other parts not as well developed: antenna 1 primary flagellum = 8-articulate, accessory = 7-articulate, article 2 of peduncle with 4 ventral setae 3-3; antenna 2 peduncle article 4 main setal formula = 4-3, article 5 = 2 and 2, dorsal robust setae of article 4 = 3, no midproximal facial robust seta set, ventral setae = 3 sets of 2 each plus pair of apicoposterior elongate robust setae, article 5 with 5 apical and ventral robust setae; right lacinia mobilis distal branch with 4 teeth, right accessory setal row with 7.5 multicuspidate stout setae, left accessory setal row with 8.5 multicuspidate stout setae. Gnathopod 1 propodus more slender and attenuated than in adult. Pereopod 3 merus facial setae = 2, of carpus = 2; setal formula on propodus of pereopods 3–4 = 2-1-1 and 3-1-1. Pereopod 7 basis posterior serrations = 5. Epimeron 2 facial setae = 6 and 1, epimeron 3 with 1 ventral seta, 1 setule at corner, dorsal row = 1 at rear and 6 facial. Uropod 1 robust and slender setal formulas; basofacial = 3, peduncle apicolateral = 3, outer ramus = 2, inner = 1; uropod 2 peduncle = 5, outer ramus = 1, inner = 0; uropod 3 outer ramus lateral = 1-2-2.

Adults from AM P25803 show that the robust setae on the dorsolateral margin of uropod 1 peduncle vary from 5–6.

Remarks. Zeaphoxus senecio sp. nov. differs from Z. zealandicus sp. nov. in having more robust setae on the dorsolateral margin of peduncle on uropod 1, in having similar sized robust setae on the dorsal margin of peduncle on uropod 2 and in having the proximal branch of the right lacinia mobilis much longer than distal branch.

Distribution. Tasman Sea and The Snares; 7– 507 m.

Figures

Figure 17.Zeaphoxus seneciosp. nov., holotype, female “d”, NIWA 115621, 12.58 mm,The Snares, New Zealand.Scales represent 0.1 mm.

Figure 18. Zeaphoxus senecio sp. nov., holotype, female “d”, NIWA 115621, 12.58 mm, The Snares, New Zealand. Scales for G1–2, P3 represent 0.5 mm, other scales represent 0.1 mm.

Figure 19. Zeaphoxus senecio sp. nov., juvenile “f-1”, AM P39545, 3.82 mm, eastern Tasman Sea. Scales represent 0.1 mm.