Renella lowryi, Labay, 2023

Labay, Vjacheslav S., 2023, A new deep-sea species of Renella (Amphipoda: Lysianassida: Pakynidae) from the Sea of Okhotsk, Zootaxa 5325 (3), pp. 419-428 : 421-426

Renella lowryi sp. nov.

Figures 1–6

Type material. Holotype female, 4.85 mm, X-54594/Cr-2453, slope of western Kamchatka Peninsula, Sea of Okhotsk , Far East of Russia (58º0334’N 154º5505’E, 396 m), silt, N.V. Shalaputin, 31 July 2020 . Paratype: female, 4.6 mm, X-54596/Cr-2454, slope of western Kamchatka Peninsula, Sea of Okhotsk , Far East of Russia (57º7996’N 154º3312’E, 457 m), silt, N.V. Shalaputin, 31 July 2020 . Paratype: female, 4.2 mm, X-54597/Cr-2455, slope of western Kamchatka Peninsula, Sea of Okhotsk , Far East of Russia (55º577’N 154º4402’E, 202 m), silt, N.V. Shalaputin, 06 August 2020 .

Type locality. The western slope of Kamchatka Peninsula, Okhotsk Sea, Far East of Russia (200–460 m).

Etymology. Named in memory of famous Australian carcinologist James K. Lowry, who is the largest specialist in the taxonomy of Amphipoda in total, and of the family Pakynidae in particular.

Diagnosis. Body shape slender. Small dorsal spine present on pereonite 5. Eyes are absent. Head lateral cephalic lobe large, rectangular.Antenna 1, peduncular articles 1–3 short, compressed, peduncular article 1 with posterodistal spine; accessory flagellum article 1 short; peduncular article 3 and flagellum with callynophore in female. Mandible with accessory setal row on the plinth, present on both sides; left lamina dentata is absent; palp attached distally; palp article 2 broad, article 3 with anterior margin convex, not tapered distally. Maxilla 1, outer plate, an apical row of 6 setalteeth (ST1–ST6) with medial cusps, STA–STD present; palp vestigial, 2-articulate. Maxilliped inner plate small; outer plate large, reached or extended the distal end of palp article 4; palp 4-articulate, article 4 large, with nail. Gnathopod 1 with chela, ischium smaller than propodus; carpus extremely compressed, hidden by propodus, posterior margin of propodus well developed, palm with produced corner (thumb), corner of palm with complex of robust seta, terminal robust seta differs from the rest, similar to a multi-cusp tooth. Gnathopod 2 propodus with small chela. Epimeron 3 posteroventral corner broadly rounded. Uropod 3 biramous, inner ramus longer than first article of outer ramus.

Description. Female (4.85 mm). Vital body color unknown. Specimens of alcohol fixation are colorless. Body shape slender. Small dorsal spine present on pereonite 5 ( Fig. 2a , 3a ). Body surface with rare specific sensible setae: with short stout branch near the base of stalk and with short thin branch at the proximal 1/3 ( Fig. 2i, j ).

Head without eyes, lateral cephalic lobe large, quadrate; ventral margin slightly convex. Antenna 1 peduncular article 1 with postero-distal spine, anterior margin with sharp keel curved inward, peduncular articles 2 and 3 short, compressed longitudinally, peduncular article 3 with strong 1-field callynophore; accessory flagellum 2-articulate, flagellum 6-articulate ( Fig. 2b, c, i ). Antenna 2, peduncular article 4 subequal to article 5 in length; flagellum short, shorter than peduncular articles 4 and 5 together, 5-articulate ( Fig. 2d ).

Mouthparts. Mandible, lacinia mobilis is a simple robust seta; lamina dentata absent; accessory setal row present, on raised setose ridge; molar a bare flap; palp attached slightly distally; palp article 2 broad, slightly longer than article 3, with 3 setae along distal half; article 3 with anterior margin convex, not tapered distally, with posterior row of 3 D3-setae, with one long plumose distal E3-seta and one long simple E-3 seta ( Fig. 2f, g, h ). Maxilla 1 outer plate with 9 setal-teeth in 6/3 arrangement (ST1–6 and STA, STC, STD), setal-teeth with medial cusps; palp vestigial, 2-articulate, apical seta is present ( Fig. 3b ). Maxilla 2: inner plate narrow, about ¾ as long as outer plate, with 3 apical setae; outer plate with a row of 8 apical setae ( Fig. 3c ). Maxilliped, inner plate small, with 2 apical setae; outer plate large; palp 4-articulate, article 2 with 3 setae along distal half, article 3 with a crown of long simple setae along distal margin, article 4 large with nail ( Fig. 3d, e, n ).

Coxal plates 1–3 with single notch at the posterior distal angle ( Fig. 3k, l, m ). Coxal plate 4, posterior margin with a semicircular notch in a proximal half ( Fig. 5c ).

Gnathopod 1 chelate; basis without setae; ischium smaller than propodus, not swollen postero-proximally; merus with 3 setae along posterior margin; carpus extremely compressed; propodus length about 2 × breadth, posterior margin well developed, palm with produced corner, corner of palm with complex of robust seta, terminal robust seta differs from the rest, similar to a multi-cusp tooth; dactylus reaching to corner of palm, with nail ( Fig. 4a, b, c, g ). Gnathopod 2 minutely chelate; merus and carpus with strong field of thin setae; propodus about 2.2 times as long as broad, with oblique distal margin, with a dense tuft of thin setae, palm with produced corner, distal margin with a row of about 8–9 bicuspid setae ( Fig. 4d, e, f, h ). Pereopods 3 and 4 similar except coxal plate 4 with well developed postero-ventral lobe with a sharply rounded postero-proximal corner; propodus in both pereopods slightly shorter than merus, merus not overlapping carpus along antero-distal margin; merus and carpus of pereopod 3 with single seta on the posterior margin and with one seta on postero-distal angle; merus and carpus of pereopod 4 with 2–3 setae along posterior margin and with one seta on postero-distal angle ( Fig. 5a, b, c, d ). Pereopod 5: basis slightly broader than long, posterior margin with postero-distal corner, anterior margin without long setae, only one long seta on the antero-distal angle; merus strongly expanded posteriorly with a broadly rectangular postero-proximal shoulder; dactyl short, stocky ( Fig. 5e ). Pereopod 6: basis slightly longer than broad, posterior margin straight with subrectangular postero-ventral corner; merus with semicircular posterior margin; dactyl short, stocky ( Fig. 5f ). Pereopod 7: basis slightly longer than wide, posterior margin evenly rounded, anterior margin without long setae; merus strongly expanded postero-distally; dactyl short, stocky ( Fig. 5g ).

Epimeral plates ( Fig. 5h, i, j ): plate 1 anterior margin with projection, postero-ventral corner broadly rounded. Epimeral plate 2, anterior margin with projection, posterior margin with 2 notches. Epimeral plate 3 anterior margin without projection, postero-ventral corner broadly rounded.

Uropod 1: peduncle slightly longer than rami; rami subequal in length, with a small terminal robust seta each ( Fig. 6d ). Uropod 2 shorter than uropod 1; rami subequal in length, with a small terminal robust seta each, outer ramus with small mid-dorsal spine-like seta ( Fig. 6e ). Uropod 3 twice shorter than uropod 2, biramous; peduncle shorter than rami; inner ramus slightly shorter than outer ramus ( Fig. 6f ). Telson weakly emarginate, broader than length, with 2 pair of minute setulae along ( Fig. 6g ).

Ecology: Renella lowryi sp. nov. was found in the depth of 200–460 m on the silt bottom.

Distribution: The slope of Sea of Okhotsk near the western Kamchatka Peninsula in 200–460 m depth.

Remarks. R. lowryi sp. nov. differs from R. sculptidentata by the absent eyes, by the formula of crown spinetooth arrangement on the outer plate of maxilla 1, by the setacea of the basis of pereopod 5 and other ( Table 1 ).

Figures

FIGURE 1. Map of sampling of Renella lowryi sp. nov..

FIGURE 2. Renella lowryi sp. nov., holotype, female, 4.85 mm: a—lateral view, b—antenna 1, c—additional flagellum of antenna 1, d—antenna 2, e—upper lip, f, g—left mandible, h—incisor, raker setae and molar of right mandible; paratype, female, 4.6 mm: i—cephalon, j—sensitive seta of surface; scales: a—1 mm; b, c, d, e, f, g, h—0.1 mm; i—0.2 mm; j—0.02 mm.

FIGURE 3. Renella lowryi sp. nov., holotype, female, 4.85 mm: a—pereon and epimeron, dorsal projection, b—maxilla 1; c—maxilla 2, d—maxilliped, e—palp of maxilliped, f, g, h, i, j—coxal gills 2–6, k, l, m—posterior lower corners of coxal plates 1–3; paratype, female, 4.6 mm: n—inner plate of maxilliped; scales: a—1 mm, f, g, h, i, j—0.5 mm, b, c, d, e, k, l, m, n—0.1 mm.

FIGURE 4. Renella lowryi sp. nov., holotype, female, 4.85 mm: a, b—gnathopod 1, inner side, c—chela of gnathopod 1, outer side, d, e –gnathopod 2, outer side, f—chela of gnathopod 2, inner side; paratype, female, 4.6 mm: g—pollex of gnathopod 1, h—gnathopod 2; scales: a, d, h—0.5 mm; b, c, e, f—0.1 mm; g—0.02 mm.

FIGURE 5. Renella lowryi sp. nov., holotype, female, 4.85 mm: a, b—pereopod 3, c, d—pereopod 4, e—pereopod 5, f— pereopod 6, g—pereopod 7, h, i, j—epimer 1–3, k—pleopod 1, l—coupling spines of pleopod 1, m—coupling setae of pleopod 1; scales: a, b, c, d, e, f, g, h, i, j, k—0.5 mm; l, m—0.1 mm.

FIGURE 6. Renella lowryi sp. nov., holotype, female, 4.85 mm: a—pleopod 2, b—pleopod 3, c—coupling spines of pleopod 3, d—uropod 1, e—uropod 2, f—uropod 3, g—telson; scales: a, b—0.5 mm; c, d, e, f, g—0.1 mm.