Palabriaphoxus palabria
Creators: name: Taylor, Joanne
name: Peart, Rachael A.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Phoxocephalidae
Palabriaphoxus
Palabriaphoxus palabria

description: Palabriaphoxus palabria (J. L. Barnard, 1961)
Figs 1–5
Harpinia palabria J. L. Barnard, 1961: 71, fig. 41.
Palabriaphoxus palabris Gurjanova, 1977: 74, fig. 4.
Holotype: NHMD CRU 7687, female, eastern Tasman Sea, 40°10'S 170°10'E, 610 m, Globigerina ooze, RV Galathea, PGI 0.2, Station 626, 20 January 1952. Paratypes: NHMD921700, 10 specimens, collected together with holotype.
Additional material examined. AM P39535, female “k”, 3.47 mm; AM P39536, female “m”, 3.35 mm; AM P39537, female “n”, 2.65 mm; AM P39538, “p”, 3.16 mm; AM P39539, “q”, 2.63 mm; eastern Tasman Sea, 42°53.9'S 170°0.5'E, anchor box dredge, 245 m, P. K. Probert on RV Tangaroa, 19 February 1982, cruise 1131, Station Q692. NIWA 115623, “a-1”, 3.45 mm; NIWA 115624, female “z”, 3.43 mm; NIWA 115625, male “y”, 3.38 mm; NIWA 115626, eastern Tasman Sea 41°58.5'S 170°28.1'E, anchor box dredge, 507 m, P. K. Probert on RV Tangaroa, 4 March 1982, cruise 1131, Station Q723.
Diagnosis. Eyes absent. Antenna 1 peduncular article 1 ventral apex not ensiform, peduncle article 2 elongate and setae placed in middle. Antenna 2 peduncle article 3 with 2 stiff robust setae plus setule, peduncular article 4 elongate with facial robust setae. Left mandible lacinia mobilis with 4 teeth. Right mandible lacinia mobilis bifid. Maxilla 1 inner plate shorter than outer, outer plate with 11 robust setae. Maxilliped palp article 3 not produced. Posteroventral corner of coxae 1–3 with small acute tooth. Gnathopods 1–2 carpus not cryptic. Gnathopod 2 enlarged, propodus with robust seta near palmar corner. Pereopods 3–4 carpus setae placed near anterodistal margin. Slender seta forming dominant posterior element on pereopods 3–4 carpus. Pereopod 5 basis narrow, much longer than wide. Pereopod 6 basis anterior margin setose with long robust setae, posterodistal corner produced as toothed lobe. Pereopod 7 merus, carpus, and propodus narrow; dactylus long. Urosome with basoventral setae. Epimera 1–2 with facial setae. Uropods 1–2 rami with robust seta. Uropod 1 peduncle with enlarged robust setae. Uropod 2 peduncle with mixture of robust and slender setae. Uropod 3 outer ramus article 2 with 2 long apical setae; inner ramus short, about 0.6 × the length of outer. Telson deeply cleft, apically with 3 slender plumose setae, marginally with 4 long plumose setae on each side, with lateral robust setae. Description. FEMALE, based on non-type, AM P39535, specimen “k”, 3.47 mm.
Head: Eyes absent; rostrum entire, unconstricted, reaching middle of article 1 of antenna 1; posteroventral corner of head produced into large tooth curved anteriorly. Antenna 1 peduncle article 1 stout, 1.2 × as long as wide, ventral margin with 3 setules and 2 plumose setae (distal corner), dorsal margin unproduced distally with 1 distal setule; article 2 narrower than but as long as article 1, ventral margin with 4 long plumose setae, facial margin with 1 brush seta; article 3, short, ventral margin with 2 setae, facial margin with 1 plumose and 1 simple seta; primary flagellum 5-articulate; accessory flagellum 5-articulate, fifth articles reduced. Antenna 2 peduncle article 3 ventral margin with 2 simple setae, dorsal margin with 1 short seta distally; article 4 ventral margin with 8 long plumose setae, facial margin with row of 14 robust (becoming less robust distalwards) short setae, dorsal margin with 4 long plumose setae; article 5 0.6 × length of article 4, ventral margin with 5 plumose, and 1 distal robust setae; flagellum 5-articulate.
Mouthparts: Left mandible molar weakly elongate, plaque armed with 2 short robust setae, 1 long plumose seta and 1 large-toothed robust seta, incisor with 4 teeth divided into 2 groups, lacinia mobilis with 4 teeth, accessory setal row with 7 multicuspidate stout setae, palpar hump medium; palp 3-articulate, article 1 0.5 × article 2, article 2 straight, narrow, with 1 elongate inner apical seta and no other short inner setae and no outer setae, 0.7 × article 3, article 3 apex oblique with 5 long, slender setae. Right mandible incisor blade like with 3 teeth and notch, lacinia mobilis bifid, distal branch flabellate shorter than proximal, accessory setal row with 7 multicuspidate stout setae. Maxilla 1 inner plate with 4 apical plumose setae; outer plate with 11 stout multicuspidate setae; palp 2-articulate, article 2 with 4 slender setae forming row medially and 5-toothed robust setae laterally and apically. Maxilla 2 inner plate subequal to outer plate but slightly narrower, with 11 plumose setae; outer plate with 13 long pectinate setae apically stretching laterally. Maxilliped inner plate with 1 short robust seta apically and 7 long plumose setae apicofacially and medially; outer plate with 8 medial and apical robust setae, 3 apicolateral setae; palp article 1 without apicolateral setae, article 2 medial margin weakly setose, article 3 not produced, without upper facial setae, no lateral setae, article 4 short to medium, subtriangular, with 1 seta laterally, 3 apical setae and 1 long apical nail.
Pereon: Gnathopod 1 coxa ventral margin not expanded but defined by sharp tooth, anterior margin slightly convex, with 2 plumose setae; basis about 2.4 × as long as wide, posterior margin with 4 long plumose setae medially and 2 long setae distally; ischium small and subrectangular, posterior margin with 2 simple setae; merus posterior margin with 4 plumose setae, facial margin without setae; carpus short, 2 × as long as wide, anterior margin with 2 setae distally, posterior margin with 7 long setae; propodus 2 × as long as wide, anterior margin with 2 setae distally, posterior margin without setae proximal to defining robust seta; palm setose and slightly convex, acute; dactylus reaching palmar corner, outer margin without setae, inner with 2 setae. Gnathopod 2 similar in size to gnathopod 1; coxa subrectangular with acute tooth on posteroventral corner, ventral margin with 5 plumose setae, anterior margin very weakly convex; basis about 3 × as long as wide, posterior margin with 7 long plumose setae and 2 distally, anterior margin with 2 plumose setae; ischium small and subrectangular, posterior distal corner with 3 long plumose setae; merus margins without setae; carpus short, subtriangular, 2 × longer than wide, margins without setae; propodus 2 × as long as wide, anterior margin with tuft of setae distally, posterior margin weakly setose, with 1 robust seta defining palm, palm slightly convex, acute; dactylus reaching palmar corner, outer margin without setae. Pereopod 3 coxa subrectangular, ventral margin with 6 plumose setae, posteroventral corner produced to form small acute tooth; basis 3.5 × as long as wide, posterior margin with 5 long plumose setae and distally tipped with 3 long plumose setae, anterior margin without setae; ischium small and subrectangular, posterior margin with 4 distal plumose setae; merus weakly inflated, anterodistal corner bearing 3 setae, posterior margin moderately setose with 12 medium to long plumose setae; carpus posterior margin moderately setose, with 7 plumose setae, with 4 facial plumose setae; propodus posterior margin without setae, facial surface with 4 long setae; dactylus 0.75 × length of propodus. Pereopod 4 coxa expanded posteriorly to form broadly rounded lobe, ventral margin with 12 long plumose setae and 2 very small simple setae, distal articles similar to pereopod 3. Pereopod 5 coxa weakly bilobate, expanded posteroventrally, posteroventral lobe with 3 plumose setae; basis narrow and straight sided, 4.4 × as long as wide, anterior margin with 1 long seta marginally and 1 plumose seta distally, posterior margin without setae; ischium small and subrectangular, anterior margin with 2 long plumose setae distally; merus anterior margin moderately setose, with 15 long slender plumose setae marginally and 8 distally, posterior margin with 3 long plumose setae marginally and 2 long plumose setae distally; carpus anterior margin moderately setose, with 4 long plumose setae marginally and 5 long plumose setae distally, posterior margin with 5 plumose setae marginally and with 4 setae distally; propodus anterior margin with 6 long plumose setae marginally and 2 long plumose setae distally, posterior margin with 2 long plumose setae marginally and 2 distally, no facial setae are present; dactylus 0.52 × as long as propodus. Pereopod 6 much longer than all other pereopods; coxa weakly expanded posteroventrally, posterior margin with 1 short seta and not covered with setules; basis about 1.59 × as long as wide, anterior margin convex, bearing 8 slender robust setae marginally, no distal setae, posterior margin concave distally fringed with even, fine, slender setae, expanded to form toothed proximal lobe bearing 3 long plumose setae between each tooth; ischium small and subrectangular without setae; merus: carpus: propodus length ratio 1:1.1:0.95; merus as long as wide, anterior margin without robust setae but with sets of slender simple setae (2-3-3-3-7) along margin and distally, posterior margin with 6 long slender setae (of which 1 plumose), distally with 5 slender simple setae and 1 long robust seta, 2 small slender setae on facial surface; carpus 1.2 × longer than wide, anterior margin lined with 15 long slender setae and 1 facially, posterior margin with 16 long slender setae marginally, distal corner with 1 long robust seta and 2 rows each with 6 long slender setae; propodus 1.6 × as long as wide, 0.8 × length of carpus, anterior and posterior margins lined with 15 and 10 long slender simple setae respectively; dactylus elongate, 1.6 × length of propodus. Pereopod 7 coxa small and subtrapezoidal, slightly expanded posteriorly, posterior margin with 1 short seta; basis as long as wide (including the posteroventral lobe), strongly expanded posteroventrally to form strongly-toothed posteroventral lobe reaching beyond the distal margin of propodus, anterior margin bearing 7 small slender setae marginally and 3 long plumose setae distally, posterior margin strongly serrate, with plumose setae in inter-dental notches, 8 in total, 2 small setae on facial surface; ischium subrectangular, 1.3 × as long as wide, anterior margin with 7 long slender plumose setae starting marginally and extending to facial surface; merus subequal in length to ischium, anterior margin with 2 robust and 1 slender setae, posterior margin with 1 slender seta distally; carpus short 0.6 × merus length, anterior margin with 2 distal slender simple setae, posterior margin with 4 slender simple setae distally; propodus narrow and 1.3 × carpus, anterior and posterior margins with 3 and 4 setae respectively; dactylus elongate, 1.2 × longer than propodus.
Pleon: Epimeron 1 anteroventral corner without setae, ventral margin with fringe of small fine setae, posterior margin convex, posteroventral corner with 4 long plumose slender setae, posterior margin with 4 small setae. Epimeron 2 anteroventral corner rounded, ventral margin with fringe of fine setae anteriorly followed by row of 7 long slender plumose setae reaching to posteroventral corner, posteroventral corner subquadrate, posterior margin straight with 4 long slender setae, facial surface with arc of 4 long slender simple setae. Epimeron 3 anteroventral corner rounded, ventral margin weakly concave lined with 12 long, slender, simple setae, posteroventral corner produced to form long acute, curved projection, posterior margin without setae, facial surface with 2 arcs of long slender, simple setae, the dorsal arc with 12 setae, ventral arc with 3 setae. Uropod 1 peduncle 1.9 × as long as wide, dorsomedial margin with 1 large robust seta and 3 long slender simple setae, dorsolateral distal corner with 1 large robust seta; outer ramus dorsal margin with 1 robust seta proximally and 7 long slender simple setae along margin and 3 slender simple setae sub-apically; inner ramus slightly shorter than outer, dorsal margin with 4 long slender simple setae marginally and 3 slender simple setae sub-apically. Uropod 2 peduncle 1.6 × as long as wide, dorsomedial margin with 1 slender, simple seta distally, dorsolateral margin with 4 long robust setae proximally, then 5 long slender simple setae marginally and then 1 large robust seta apically; outer ramus dorsal margin with 6 long slender simple setae marginally and 3 long slender simple setae sub-apically; inner ramus shorter than outer, dorsolateral margin with 1 slender seta and 1 long slender seta sub-apically. Uropod 3 peduncle 1.3 × as long as wide, with 3 long slender plumose setae ventrodistally and 1 robust seta dorsodistally; outer ramus 2-articulate, article 1 ventrolateral margin with 10 long setae and 3 long setae apically, dorsolateral margin with 3 long slender setae marginally and 1 long seta apically; article 2 tiny 0.08 × length of article 1, as long as wide, tipped with 2 long plumose slender setae; inner ramus 0.65 × length of outer ramus, outer margin lined with 4 long slender plumose setae and 2 long slender setae apically. Telson short, completely cleft, each lobe broad and weakly truncated apically, has 2 mid-facial short plumose setae, 4 slender plumose marginal setae (3 long 1 short) and 3 long slender plumose apical setae. Urosomite 3 with 2 long slender plumose setae either side of telson insertion.
MALE, based on NIWA 115625, male “y” 3.38 mm.
Head: Rostrum 0.63 × length of antenna 1; posteroventral corner of head produced into large tooth directed ventrally. Antenna 1 peduncle article 1 stout, as long as wide, ventral margin with distal tuft of slender simple setae and 2 plumose setae (distal corner), dorsal margin unproduced distally with 1 distal setule; article 2 narrower than and shorter than (0.86 ×) article 1, ventral margin with 6 long plumose setae, without facial setae; article 3 short triangular, ventral, and facial margins without setae; primary flagellum 8-articulate, last article reduced, article 1 with callynophores occupying most of surface; accessory flagellum 5-articulate, fifth article reduced. Antenna 2 peduncle article 4 ventral margin with 10 long evenly spaced plumose setae, facial margin with uneven row of 13 slender short setae, dorsal margin lined with 8 tufts of 4–12 long slender simple setae; article 5 0.5 × length of article 4, ventral margin with 3 marginal plumose setae and 3 distal long plumose setae; flagellum 9-articulate.
Mouthparts: Right mandible with 7 accessory setae, left with 8, left lacinia mobilis with 3 teeth, main robust seta of molar less serrate, on left side with 4 denticles on apex, palp with extra inner subapical seta. Palp of maxilla 1 with 5 robust setae and 3 slender facial setae, remainder as in female; inner plate of maxilla 2 with 3 medial setae, outer plate with 2 lateral setae; inner plate of maxilliped with 4 medial setae, outer plate with 8 seta-teeth and 3 setae, dactylus with 2 accessory setae.
Pereon: Coxae 1–3 ventral margins without prominent extended acute tooth on posteroventral corner. Gnathopods 1–2 palms without defining robust setae. Pereopod 6 basis proximal posterior lobe reduced and not serrate, row of setae on posterior margin distinct, composed of 8 long, slender, plumose setae, not fringe like, anterior margin with 4 short simple proximal setae, and 6 long, plumose distal setae; ischium with 4 long plumose setae on distal half of anterior margin; merus: carpus: propodus length ratio 1:0.75:0.98; merus, carpus, and propodus all narrower than in female, of different proportions; merus, carpus, and propodus all with rows of facial short robust setae, no long plumose setae. Pereopod 7 basis expanded but lobe only weakly serrate, inter-tooth setae small and simple, lobe only reaching to end of merus; carpus longer in proportion to propodus; dactylus as long as propodus.
Pleon: Epimeron 2 with more setae in facial arc. Epimeron 3 with more setae in upper facial arc, arc straight not curved. Uropod 3 peduncle 1.7 × as long as wide, with 2 robust setae distally; outer ramus, article 1, margins covered with long plumose setae, article 2, with 2 long plumose setae apically; inner ramus shorter than outer ramus, margins covered with long plumose setae. Pleopods 1–3: coupling hooks 2 and 2 accessories; posterior facial setae on peduncle = 15+-10+-10+; articles on outer rami = 12-13-12, inner rami = 10-10-10; setae on article 1 of outer and inner rami respectively, on outer and inner sides respectively = 8-2-1-5, 8-1-1-5, 8-2-1-5.
Remarks. Palabriaphoxus palabria has previously been recognized as the only species of this genus occurring in New Zealand waters and was thought to range around the entirety of the New Zealand coastline. This study and further observations bring this supposed expansive distribution into doubt.
Palabriaphoxus palabria can be distinguished by the long rows of facial setae on the epimera 2–3 (P. barnardi facial setae absent, P. lowryi facial setae present only on epimeron 3); coxa 1–4 of female have an obvious, small acute tooth on the posteroventral corner, the male has this tooth but greatly reduced (P. barnardi tooth is reduced, P. lowryi unable to be seen); pereopod 6 basis has a serrated (various size with male and female) proximal posterior corner (absent in P. barnardi and P. lowryi).
Palabriaphoxus palabria is closest morphologically to P. barnardi with the main differences being the length of the antenna 1 article 2 (P. palabria, elongate; P. barnardi, short), antenna 2 peduncle article 4 (P. palabria, elongate, P. barnardi short); basoventral urosomal setae on urosome (P. barnardi absent); telson with lateral robust setae (P. barnardi robust setae absent).
Closer investigation of the numerous collections identified as P. palabria from around New Zealand, beyond the scope of this study, will most likely show that many are referable to one of the two new species described below as well as additional new species. This will most likely reduce the confirmed geographical range of P. palabria.
Distribution. Previously regarded as circum-New Zealand, but currently known with certainty only from off Westland; other New Zealand records require confirmation. New Zealand, 10– 610 m.
description: Published as part of 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, pp. 567-600 in Records of the Australian Museum (Rec. Aust. Mus.) (Rec. Aust. Mus.) 75 (4) on pages 569-575, DOI: 10.3853/j.2201-4349.75.2023.1894, http://zenodo.org/record/10413515