Tironella bathyalis, Just, 2022

Just, Jean, 2022, Tirons of the world: a review of ‘ tironid’ amphipods, description of new genera and species, and establishment of a new subfamily Tironinae Stebbing, 1906 stat. nov. (Crustacea, Synopiidae), Zootaxa 5139 (1), pp. 1-89 : 19-22

Tironella bathyalis sp. nov.

( Figs 8–9 )

Type fixation. Holotype, ♀.—Here designated.

Etymology. The epithet reflects that this species occur at upper bathyal depth on the eastern Bass Strait slope.

Material examined. Holotype, ♀, 5.4 mm. Australia, New South Wales, Off Eden, 37˚00.36’S, 150˚20.42’E, 363 m, coarse shell, epibenthic sled, GCB Poore et al., 16 February 1987, RV Franklin , SLOPE stn 22, NMV J73738 .

Paratypes. Same data as holotype, NMV J75150 (anterior half of adult ♀, 1 young specimen of 4.4 mm) .

Description (female). Rostrum apex sharply right-angled. Interantennal lobes bluntly rounded at nearly right angle.

Mouthparts. Maxilla 1 palp apex with 5 acute, finely deticulate setae and 1 lateral curved seta; outer plate with 9 variously dentate spine-setae. Mouthparts otherwise normal.

Antenna 1 as long as pereonite 1–6 combined along dorsum, peduncle article 2 about 2/3 length of 1, article 3 as long as article 2, articles 1 and 2 with robust seta in dorsoapical corner, otherwise sparsely setose; flagellum about 1.2 longer than peduncle, of 10 articles, accessory flagellum of 4 articles. Antenna 2 as long as pereonites 1–7 combined along dorsum, peduncular article 4 the longest, flagellum of 8+ articles, most articles with single slender robust seta dorsodistally, antenna otherwise sparsely setose.

Gnathopods 1 and 2 basis with row of long setae anteriorly and a few long setae on posterior margin; propodus of pereopod 1 with row of strong pectinate setae, of gnathopod 2 with simple setae.

Pereopods 3–4 basis about 5 times longer than wide, as long as rest of pereopod, with anterior margin row of small setae, a few longer setae in posterodistal corner. Pereopod 5 basis broadest in distal half. Pereopod 6 basis ovoid. Pereopod 7 basis nearly circular, shorter than pereopod 6 basis, medial surface with row of small setae and similar scattered setae, propodus about half as long as carpus.

Uropod 2 rami presumed of subequal length (see Fig.10 us) reaching to base of outer ramus of uropod 3. Uropod 3 peduncle about half as long as outer ramus, rami elongate oval, reaching beyond apex of telson, outer ramus with row of 8 robust setae dorsally, and 8–9 smaller robust setae ventrally, inner ramus reaching to 9/10 of outer ramus, dorsal margin with row of long setae and 2 robust setae, pointed apex with 2 robust setae.

Telson. Length about 4 times greatest lateral depth, reaching 3/4 along outer ramus of uropod 3, length/width 2.5, with row of 7 small robust setae and a few small simple setae dorsally on each lobe, apices with 1 long and 1 short robust seta.

Size. Largest ♀, 5.4 mm. ♂ not known.

Distribution. SE Australian slope; 363 m.

Figures

FIGURE 8. Tironella bathyalis gen. et sp. nov. Holotype, ♀, except P, Pseudotiron pervicax. clv, head lateral view; mx1, maxilla 1; P clv, lateral view of head of P. pervicax (from J.L. Barnard, 1967, fig. 84 k); tel, telson; us, urosome.

FIGURE 9. Tironella bathyalis gen. et sp. nov. Holotype, ♀, except P, Pseudotiron pervicax. dac, dactylus with unguis; P dac, dactylus with unguis of P. pervicax (from J.L. Barnard, 1967, fig. 84 g); gp1, gnathopod 1; p4–7, pereopods 4 to 7.

FIGURE 10. Tironella altifrons (Reid, 1951) comb. nov. Holotype, ♂. clv, head and antennae; p3, pereopod 3; p.5–7, pereopods 5 to 7; us, urosome. (clv and us from Reid 1951, fig.31).