Protophoxus australis (K. H. Barnard, 1930 )

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 : 585-588

Protophoxus australis (K. H. Barnard, 1930)

Figs 12–14

Phoxus batei .— Thomson, 1882: 232–233, pl. 17, figs. 2a–e (not Haswell, 1879).

Protophoxus australis K. H. Barnard, 1930: 335–336 , fig. 12a–c.

Pontharpinia australis .— Hurley, 1954: 581–587, figs. 1–28.

Material examined. AM P25859 , specimen “q3”, female, 5.5 mm, Otago Shelf , New Zealand, 45°51'S 170°57'E, sand bottom, 132 m, P. K. Probert on RV Munida , MU74 /114, 4 June 1974 ; NIWA 115616 , specimen “q1”, juvenile male, 3.41 mm, off west coast of South Island , New Zealand, 40°51.8'S 171°28'E, 195 m, P. K. Probert on RV Tangaroa, Cruise 1131 , Q729, 6 March 1982 .

Diagnosis. Eyes present. Head with 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. Maxilla 1 inner plate moderately large, outer plate with 11 multicuspidate robust setae. Maxilliped palp article 3 not 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 with facial setae. Uropods 1–2 rami never fully spinose. Uropod 1 peduncle with displaced robust seta only on lateral apex. 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 2 robust setae per lobe, marginally without setae on each side, without lateral robust setae.

Description. FEMALE, based on AM P25859, female “q3”, 5.5 mm.

Head: Eyes medium, largely occluded with pigment. Head about 0.20 × body length, greatest width about 0.70 × length; rostrum constricted, of medium breadth, reaching end of article 1 on antenna 1. Antenna 1 peduncle article 1 1.5 × as long as wide, 2 × as wide as article 2, ventral margin with 6 setules, weakly produced dorsal apex with 3 setae; article 2 0.6 × as long as article 1, with ventral horseshoe cycle of 20 setae; primary flagellum 11-articulate, 0.84 × as long as peduncle, lacking large aesthetascs; accessory flagellum with 9 articles. Antennae 2 peduncle article 4 facial setal formula = 5-4-3, dorsal margin with 2 robust setae, ventral margin with 6–7 groups of 1–4 long to medium setae, 1 distoventral elongate robust seta; article 5 flabellate 0.8 × as long as article 4, facial setal formula = 2-2-1, ventral margin with 4 sets of 1 short and 1 elongate seta each, 1 distoventral medium robust seta; flagellum 1.6 × as long as articles 4–5 of peduncle combined, 12-articulate.

Mouthparts: Mandibles with small palpar hump; right incisor with 5 teeth; left incisor with 5 teeth in 2 weak sections; right lacinia mobilis bifid, distal branch flabellate, scarcely shorter than proximal, proximal section simple, pointed; left lacinia mobilis with 4 teeth; right accessory setal row with 7 multicuspidate stout setae, left with 8; molar bulbous, weak, with 1 thick penicillate seta in middle, disjunct from 2 slightly smaller simple robust setae, each molar with gross patch of fine setae; palp article 1 short, article 2 with 3 elongate inner setae and 2 other short inner setae, article 3 1.1 × as long as article 2, oblique apex with 11 long, slender setae. Maxilla 1 inner plate moderately large, with 2 elongate apicofacial pappose setae (1 on each face), 2 apicolateral much shorter simple setae; palp article 2 with 2 medial marginal setae, and 5 apical marginal setae (1 robust and 4 slender simple) and 2 submarginal setae. Maxilla 2 plates extending subequally, of subequal breadth, outer with 6 apicolateral setae, inner with 2 medial setae. Maxilliped inner plate with 2 large apical robust setae, 4 apicofacial setae, 4 medial setae; outer plate with 11 medial and apical robust setae, 4 apicolateral setae; palp article 1 with 1 apicolateral seta, medial margin of article 2 moderately setose, article 3 not produced, with 9 facial setae, 3 lateral setae, nail of article 4 medium, with 1 accessory setule.

Pereon: Coxa 1 scarcely expanded distally, anterior margin almost straight, main ventral setae of coxae 1–4 = 10-9-8-4, posterior most seta of coxae 1–2 shortened. Coxa 4 anterior and posterior margins divergent, posterior margin oblique, convex, posteroventral margin not bevelled, posterodorsal corner subrounded, posterodorsal margin short, concave, width to length ratio of coxa 4 = 30:35. Coxae 5–7 posteroventral setule formula = 2-4-4. Gnathopods 1–2 small, slender, weakly diverse; width ratios of carpus-propodus on gnathopods 1–2 = 11:16 and 10:16, length ratios = 23:30 and 18:29; palmar humps ordinary, palms acute; gnathopods 1–2 carpus medium and short respectively, of gnathopod 1 ovate, posterior margin of 1 rounded, of 2 scarcely lobate, of gnathopod 2 short, subtriangular. Pereopods 3–4 similar, facial setae formula on merus = 7 and 5, on carpus = 7 and 7; main robust seta of carpus extending to M. 95 on propodus, carpus without posteroproximal robust setae; setal formula of propodus = 5-5 plus 1, mid-distal robust seta acclivity on inner margin of dactyli of pereopods 3–4 moderately large. Pereopods 5–6 merus-carpus of medium width, facial robust setal rows poorly developed. Pereopods 5–7 basis facial ridge formula = 0-1-1, ridge of pereopod 7 long. Pereopod 5 basis slightly tapering distally; width ratios of basis, merus, carpus, propodus of pereopod 5 = 17:11:10:5, of pereopod 6 = 27: 18:9:? (broken), of pereopod 7 = 37:9:8:4, length ratios of pereopod 5 = 29:12:16:17, of pereopod 6 = 35:33: 16:?, of pereopod 7 = 40:10:11:13. Pereopod 7 basis reaching middle of carpus. Pereopods 5 and 7 merus without elongate posterodistal lobe; medial apex of propodus truncate, finely combed.

Pleon: Epimeron 1 posteroventral corner rounded, posterior margin convex, with setule, anteroventral margin with 6 short setae, ventral margin naked, posterior corner with 3 facial setae. Epimeron 2 posteroventral corner weakly and broadly protuberant, posterior margin sinuate, facial setae in 2 groups of 8 (row) and 1. Epimeron 3 posteroventral corner rounded, posterior margin convex, smooth, with 4 setules, posteroventral face with 1 seta, midposterior face with oblique row of 6 setae. Urosomite 1 with ventrolateral and ventral row of 9+ setae, no ventral robust setae at base of uropod 1. Urosomite 3 weakly protuberant dorsally. Uropod 1 peduncle with 3 apicolateral robust setae, medially with 7 marginal slender setae and robust setae becoming thicker apically, outer ramus with 5 lateral robust setae, inner with 3 medial. Uropod 2 peduncle with 6 dorsal robust setae, medially with 1 medium apical robust seta, outer ramus with 5 dorsal robust setae, inner with 2 medial robust setae. Uropods 1–2 rami with articulate enlarged apical nails, lacking accessory nails. Uropod 3 peduncle with 6 apicoventral robust setae, dorsally with 1 lateral robust seta, 1 medial robust seta and no setules; rami feminine, inner extending to M.47 on article 2 of outer ramus, apex with 1 seta, article 2 of outer ramus elongate, 0.4 × as long as article 1, with 1 long, 1 short setae, medial margin of article 1 with 1 subequal seta, lateral margin with 3 acclivities, setal formula = 2-2-2-2. Setal formula = 0. Telson elongate, length to width ratio = 15:11, almost fully cleft, each apex medium, weakly notched, lateral acclivity absent, with apicolateral robust setae and medial setule, then middle apical robust setae, basodorsal setules diverse.

JUVENILE MALE, based on NIWA 115616, male “q1”, 3.41 mm. Mandibular palp article 2 setae shortened and less setose. Gnathopods slightly stouter and shorter; coxa 4 slightly narrowed. Epimera broadened. Main apical robust seta on each lobe of telson elongate. Uropod 3 remaining in feminine form.

Remarks. Only the male of Protophoxus australis was known previously. The female differs from the male in the fewer bulbar setules on peduncle article 1 of antenna 1, the lack of calceoli on the antennae, the smaller eyes, the narrower telson with robust setae set more directly on the apices of each lobe, the weaker setation on uropod 3, the shorter inner ramus of uropod 3 (see female-like uropod 3 of “q1” specimen), the smaller epimeron 1, the weakly sinuate posterior margin of epimeron 2, the weaker spination of the pereopods, and the stronger excavation on coxa 4.

Protophoxus australis differs from Pr. munida sp. nov. primarily by the presence of facial setae on epimeron 3 (absent on Pr. munida ) and the head in dorsal view abruptly tapering (not abruptly tapering in Pr. munida ).

Distribution. New Zealand: off Three Kings Island, surface, and Spirits Bay, North Auckland; Port Chalmers; Paterson Inlet, Stewart Island; 0–195 m depth.

Figures

Figure 12. Protophoxus australis (K. H. Barnard, 1930), female “q-3”,AM P25859, 5.5 mm, Otago Shelf, New Zealand. Scales represent 0.1 mm.

Figure 13. Protophoxus australis(K. H. Barnard, 1930), female “q-3”,AM P25859, 5.5 mm, Otago Shelf, New Zealand.Scales represent 0.2 mm.

Figure 14. Protophoxus australis (K. H. Barnard, 1930), juvenile male “q-1”, NIWA 115616, 3.4 mm, Otago Shelf, New Zealand. Scales represent 0.1 mm.