Palabriaphoxus lowryi, 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 : 579-584

Palabriaphoxus lowryi sp. nov.

urn:lsid:zoobank.org:act:745A53E5-4C2F-4FEF-9055-2CE92FA4E328

Figs 8–11

Holotype: NIWA 115627 , ovigerous female “a”, 5.20 mm, eastern Tasman Sea , 41°08.2'S 172°03.4'E, anchor box dredge, 51 m, P. K. Probert on RV Tangaroa , 5 March 1982, cruise 1131, Station Q 726 . Paratype: NIWA 115629 , female “c”, collected with holotype .

Additional material examined. AM P39540 , male “m”, 2.51 mm , AM P39541 , female “m-1”, 3.94 mm , AM P39542 , 2 specimens “m2” and “m3”; eastern Tasman Sea , 41°38.8'S 171°39.1'E, anchor box dredge, 32 m, P. K. Probert on RV Tangaroa, cruise 1131 , Station Q714, 27 February 1982 . AM P39543 , 1 female, eastern Tasman Sea , 42°24.5'S 170°57.5'E, anchor box dredge, 133 m, P. K. Probert on RV Tangaroa, cruise 1131 , Station Q717, 28 February 1982 . NIWA, specimens “h”, “i” and “j”; Senecio Pool, The Snares , 48°07'S 166°36'E, among deposits of terrestrial plant detritus, 7 m, G. D. Fenwick, 6 January 1977, SA3487 .

Etymology. The name is for Jim Lowry, in memory of his enthusiasm for amphipods and his mentoring of both authors.

Diagnosis. Eyes present. Antenna 1 peduncular article 1 ventral apex not ensiform, peduncle article 2 shortened. Antenna 2 peduncle article 3 with 5 robust setae, article 4 shortened with facial robust setae. Right mandible lacinia mobilis multi-toothed. Maxilla 1 inner plate shorter than outer, outer plate with 9 multicuspidate robust setae. Maxilliped palp article 3 not produced. Posteroventral corner of coxae 1–3 with very small acute 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 narrow, much longer than wide. Pereopod 6 basis anterior margin without setae, posterodistal corner not produced to form 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. Uropod 1 peduncle without enlarged robust setae. Uropod 2 peduncle only with robust setae. Uropod 3 outer ramus article 2 with 2 long apical setae; inner ramus long, about 1.2 × the length of outer. Telson deeply cleft, apically with 3 slender plumose setae per lobe, marginally without setae on each side, without lateral robust setae.

Description. FEMALE, based on NIWA 115627, holotype, female “a”, 5.20 mm.

Head: Eyes present, very small and partly obscured; rostrum unconstricted, broad, reaching distal end of article 3 of antenna 1 peduncle; posteroventral corner of head produced into small tooth curved anteriorly. Antenna 1 peduncle article 1 stout, 1.3 × as long as wide, 1.85 × as long as article 2, ventral margin with 6 plumose setae (distal corner and onto ventral margin), dorsal margin unproduced distally; article 2 narrower and shorter than article 1, ventral margin with 7 long plumose setae, facial margin with 1 slender seta; article 3 short and subrectangular, ventral margin with 2 setae, facial margin with 4 plumose/brush setae; primary flagellum 7-articulate, first article elongated; accessory flagellum 6-articulate. Antenna 2 peduncle article 3 ventral margin with 5 simple setae; article 4 ventral margin expanded with 6 long plumose setae, facial margin with row of 12 robust plumose (becoming less robust distalwards) short setae, dorsal margin with 1 small seta and 16 long slender plumose setae distally and 4 long plumose setae inset facially; article 5 0.7 × length of article 4, ventral margin with 8 plumose, and 1 distal small plumose setae; flagellum 8-articulate, article 8 very small.

Mouthparts: Left mandible molar as a weakly elongate plaque armed with 2-toothed robust setae, and 1 short plumose seta, incisor blade like divided into 3 teeth, lacinia mobilis with 5 teeth, accessory setal row with 9 multicuspidate stout setae, palpar hump reduced; palp not documented. Right mandible incisor blade like with 3 teeth, lacinia mobilis reduced/broken off, accessory setal row with 9 multicuspidate stout setae; palp 3-articulate, article 1 0.14 × article 2, article 2 straight, slightly inflated, with 6 elongate inner margin setae, no outer setae, 1.06 × article 3, article 3 apex oblique with 8 long, slender setae. Maxilla 1 inner plate with 4 short apical plumose setae, and setules on lateral margin; outer plate with 11 stout multicuspidate setae; palp 2-articulate, article 2 with 8 slender setae laterally and apically. Maxilla 2 inner plate subequal to outer plate but slightly narrower, with 8 plumose setae; outer plate with 13 long pectinate setae apically stretching laterally; both plates with setules. Maxilliped inner plate with 1 short robust seta apically and 6 long plumose setae apicofacially and medially; outer plate with 8 medial and apical robust setae, 3 lateral setae; palp article 1 without apicolateral setae, article 2 medial margin weakly setose, article 3 not produced, with slender facial setae, lateral setae on both margins, article 4 long subrectangular, with 2 setae laterally, 1 apical seta and 1 long apical nail.

Pereon: Gnathopod 1 coxa ventral margin expanded to form triangular shape, no posteroventral tooth, with 8 plumose setae; basis not documented; ischium small and subrectangular, posterior margin without setae; merus posterior margin with 13 simple slender setae, facial margin without setae; carpus short, 1.5 × as long as wide, anterior margin with 1 seta distally, posterior margin with 9 long setae; propodus 1.6 × as long as wide, anterior margin with 8 setae distally, posterior margin without setae proximal to defining robust seta, facial margin with 5 long slender setae; palm densely setose with many short robust setae and longer slender setae and slightly convex, acute, produced to form small subacute corner; dactylus reaching palmar corner, outer margin with 1 small seta. Gnathopod 2 slightly larger than gnathopod 1; coxa subrectangular without tooth on posteroventral corner, ventral margin with 5 plumose setae, anterior margin very weakly convex; basis not documented; ischium small and subrectangular, posterior distal corner with 5 long weakly plumose setae; merus subtriangular, posterior margin produced slightly to form small rounded lobe, with 13 long, slender weakly plumose setae, anterior margin reduced; carpus short, subtriangular, 0.84 × long as wide, posterior margin with 4 setae; propodus 1.6 × as long as wide, anterior margin with tuft of 7 setae distally, posterior margin weakly setose, with 1 robust seta defining palm, palm slightly convex, acute, produced posteroventrally to form small rounded defining corner; dactylus reaching palmar corner, outer margin with 1 small distal seta. Pereopod 3 coxa subrectangular, ventral margin with 7 plumose setae, posteroventral corner not produced to form tooth; basis not documented; ischium small and subrectangular, with 4 distal plumose setae; merus weakly inflated, anterior margin extended distally to form small rounded lobe bearing 3 long slender setae, posterior margin moderately setose with 20 medium to long plumose setae; carpus posterior margin setose, with 15 plumose setae, with 5 facial plumose setae, distal margin of article lined with fringe of short, dense robust setules; propodus posterior margin without setae, facial surface with 8 long setae in long curved row; dactylus 0.53 × length of propodus. Pereopod 4 coxa expanded posteriorly to form broadly rounded lobe, all of posterior margin convex, ventral margin with 14 long plumose setae and 2 very small simple setae; distal articles similar to pereopod 3. Pereopod 5 coxa bilobate, expanded posteroventrally, posteroventral lobe angular with 3 plumose setae; basis narrow and straight sided, 4 × as long as wide, anterior margin with 2 plumose setae distally, posterior margin with 1 seta distally; ischium small and subrectangular, anterior margin with 3 long plumose setae distally; merus anterior margin moderately setose, with 10 long slender plumose setae marginally and 7 distally, posterior margin with 4 long plumose setae marginally and 3 long plumose setae distally; carpus anterior margin setose, with 11 long plumose setae marginally and 2 long plumose and 5 long robust setae distally, posterior margin with 6 plumose and 5 long robust setae marginally and with 1 long plumose and 4 robust setae distally; propodus anterior margin with 4 long simple setae marginally and 3 long simple setae distally, posterior margin with 6 long plumose and 6 long simple setae marginally and 6 distally, facial setae absent; dactylus 0.62 × as long as propodus. Pereopod 6 much longer than other pereopods; coxa weakly expanded posteroventrally, posterior margin with 1 long plumose seta and not covered with setules; basis about 1.2 × as long as wide, anterior margin strongly convex, without setae, posterior margin almost straight, distally fringed with even, fine slender setae, not expanded to form proximal lobe, without proximal teeth; ischium small and subrectangular; merus: carpus: propodus length ratio 1:1:1.4; merus 1.3 × as long as wide, anterior margin with row of 4 small robust setae marginally and row of 5 robust setae distally, posterior margin with 8 long plumose setae and 5 short robust setae, distally without setae; carpus shorter than wide (0.75 ×), anterior margin lined with 4 rows of 3–4 robust setae each, posterior margin with 2 long slender setae and 4 rows of 4–5 robust setae marginally, distal corner with 1 long robust seta; propodus 1.8 × as long as wide, 1.4 × length of carpus, anterior and posterior margins lined with rows of 4–5 short robust setae; dactylus elongate, same length of propodus. Pereopod 7 coxa small and subtrapezoidal, slightly expanded posteriorly; basis as long as wide (including the posteroventral lobe), strongly expanded posteroventrally to form weakly-toothed posteroventral lobe reaching to distal margin of merus lobe, anterior margin bearing 2 slender setae marginally and 5 long plumose setae distally, posterior margin weakly serrate, with plumose setae in inter-dental notches, 13 in total; ischium subrectangular, 1.3 × as long as wide, anterior margin with 12 long slender plumose setae starting marginally and extending to facial surface; merus longer than ischium, anterior margin with 3 slender setae, posterior margin extended distally to form long rounded lobe extending halfway along carpal posterior margin, lobe tipped with 6 long slender setae; carpus short and subrectangular 0.6 × merus length, anterior margin with 4 long slender setae and tipped with 3 small slender simple setae, posterior margin with 3 slender simple setae distally; propodus narrow and 1.6 × carpus, anterior and posterior margins with 4 and 3 setae respectively; dactylus elongate, as long as propodus.

Pleon: Epimeron 1 setation unknown. Epimeron 2 anteroventral corner rounded, ventral margin with row of 4 long slender plumose setae reaching to posteroventral corner, posteroventral corner subquadrate, posterior margin straight with 2 short slender setae, facial setae absent. Epimeron 3 anteroventral corner rounded, ventral margin weakly convex lined with 3 long, slender, simple setae, posteroventral corner produced to form long acute, straight projection, posterior margin without setae, plate facial surface with 1 long arc of 14 long slender, simple setae. Uropod 1 peduncle 1.6 × as long as wide, dorsomedial margin with 2 long slender simple setae, dorsolateral distal corner without robust seta; outer ramus dorsal margin with 6 robust setae along margin and no setae sub-apically; inner ramus shorter than outer, dorsal margin with 1 small slender simple seta marginally and no setae sub-apically. Uropod 2 peduncle 1.6 × as long as wide, dorsomedial margin with 1 slender, simple seta distally, dorsolateral margin with 10 long slender setae marginally; outer ramus margins without setae and division resembling apical nail near the apical region; inner ramus subequal to outer, margins without setae. Uropod 3 peduncle 1.2 × as long as wide, with 4 short slender setae ventrodistally and 1 short robust seta dorsodistally; outer ramus 2-articulate, article 1 ventrolateral margin with 4 long setae and 1 long seta apically; article 2 long, thin, spiniform, 0.3 × length of article 1; inner ramus 1.2 × longer than outer ramus, outer margin with 1 long slender setae apically, inner margin with 3 long slender setae. Telson short, 85% cleft, each lobe broad, narrow apically, with 2 mid-facial short plumose setae, 3 long slender apical setae. Urosomite 3 without setae on either side of telson insertion.

MALE, based on AM P39540, male “m” 2.51 mm.

Head: Rostrum as in female; posteroventral corner of head produced into small tooth directed anteriorly. Antenna 1 peduncle article 1 stout, 1.5 × longer than wide, ventral margin with distal tuft of slender simple setae and 2 plumose setae (distal corner), dorsal margin slightly produced distally with 1 distal setule; article 2 narrower than and shorter than (0.48 ×) article 1, ventral margin with 5 long plumose setae and 3 small setules, with facial robust brush setae; article 3 short triangular, ventral margin with 6 small setae, facial margin without setae; primary flagellum 8-articulate, first article elongated and broadened, last article reduced, article 1 with callynophore occupying most of surface; accessory flagellum 6-articulate, sixth article reduced. Antenna 2 peduncle article 4 ventral margin with 4 long evenly spaced plumose setae and with 8 facial robust setae, dorsal margin lined with long slender setae with 4 long slender plumose setae and 4 robust setae distally; article 5 1.2 × length of article 4, ventral margin with 3 apical long plumose setae, dorsal margin with 4 tufts of 3–4 slender setae and 5 calceoli; flagellum at least 5-articulate. Right mandible with 9 accessory setae, right lacinia mobilis with 3 weak teeth.

Pereon: Pereopod 4 coxa proximal posterior margin concave. Pereopod 6 basis posterior straight, no lobe and smooth, anterior margin with 3 slender setae and 1 wide robust seta distally; ischium without setae; merus: carpus: propodus length ratio 1:0.9:1.2; merus, carpus, and propodus are all narrower than female and different proportions; merus, carpus, and propodus all with rows of facial short robust setae, long plumose setae absent; dactylus elongated, 1.3 × length of propodus. Pereopod 7 basis also expanded but lobe only weakly serrate, only 6 inter-tooth setae small and simple, lobe shorter, almost reaching end of merus; carpus longer in proportion to propodus; dactylus slightly shorter than propodus (0.9 ×).

Pleon: Epimeron 1 longer than epimeron 2. Epimeron 2 ventral margin with 3 long slender plumose setae. Epimeron 3 with 3 setae on ventral margin, facial arc straight with 11 slender setae. Uropod 3 peduncle 1.7 × as long as wide, with 4 robust setae distally; outer ramus article 1, margins covered with long plumose setae, and 2 robust setae, article 2 with 2 long plumose setae apically; inner ramus as long as outer ramus, margins covered with long plumose setae.

Remarks. Palabriaphoxus lowryi sp. nov., like P. barnardi will probably prove to have a wider range once the extensive series in research collections, previously identified as P. palabria , has been examined. The most obvious difference between P. lowryi and its congeners is the shape of the pereopod 7 basis (rounded and weakly scalloped, P. palabria and P. barnardi have strong elongated serrations and the basis is curved and narrower), as well as the other differences noted above.

Distribution. Eastern Tasman Sea and The Snares; 7– 133 m.

Figures

Figure 8. Palabriaphoxus lowryi sp. nov., holotype female “a”, NIWA 115627, 5.20 mm, eastern Tasman Sea. Scales represent 0.1 mm.

Figure 9. Palabriaphoxus lowryi sp. nov., holotype, female “a”, NIWA 115627, 5.20 mm, eastern Tasman Sea. Scales represent 0.1 mm.

Figure 10. Palabriaphoxus lowryi sp. nov., holotype, female “a”, NIWA 115627, 5.20 mm, eastern Tasman Sea. Scales represent 0.1 mm.

Figure 11. Palabriaphoxus lowryi sp. nov., paratype, male “m”, NIWA 115629, 2.51 mm, eastern Tasman Sea. Scale for rMD represents 0.02 mm. Scales for other parts represent 0.1 mm.