Tironella altifrons ( Reid, 1951 ) 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 : 22-24

Tironella altifrons ( Reid, 1951) comb. nov.

( Figs 10–11 )

Tiron altifrons Reid, 1951 , fig. 31.—J.L. Barnard (1972, p. 84).

Metatiron altifrons ( Reid, 1951) .— Rabindranath (1972, p. 85).

Tiron altifrons .— Lörz & Coleman (2013, p. 126); Cadien (2014, p. 11).

The material used for the re-description of Tironella altifrons ( Reid, 1951) consists of a microvial with a few crushed mouthparts, a dissected torso with a few limbs, a permanent slide with pereopods 5 and 7 (illustrated by Reid, pereopod 5 labeled as 6 by Reid), his published sketches of the head with antennae and the urosome with uropods (both reproduced in Fig. 10 ), together with his rather lengthy description. Direct quotes from Reid (1951) are given in quotation marks.

Type fixation: Holotype, ♂ (according to Reid).—By monotypy.

Material examined. Holotype, ♂, 4 mm. West Africa , Guinea off Conakry , 9˚28’N, 14˚58’ W, 45 m, shells, foraminifera, Sigsbee Trawl (1 meter), 14. April 1946, Atlantide stn 147, NHMD 83125 (including one slide). Unique.

Description. Accessory ommatidia assumed to be present ( Fig. 10 clv): “One pair of eyes is clearly visible but I cannot be sure that I have seen another pair”.

Mouthparts. Maxilla 1 palp with 2 short simple, 3 tri-cusped, and a single longer serrate robust setae; outer plate with row of 9 finely serrate pointed robust setae; inner plate damaged.

Antenna 1 reaching to middle of article 5 of antenna 2, peduncle second article 0.4 length of article 1, third article 2/3 length of article 2; flagellum subequal in length to peduncle, with 6+ articles; accessory flagellum of 3 articles. Antenna 2 peduncular article 5 about 2/3 length of article 4; flagellum of 5 articles. Both antennae sparsely setose.

Gnathopods 1 and 2 carpus posterior margin with a few groups of long and short setae; propodus with single stout, pectinate seta and a few long simple setae on posterior margin.

Pereopod 3 with a few small simple setae, merus, carpus and propodus of subequal length. Pereopods 5–6 propodus about 0.7 length of carpus; basis of pereopod 5 oval, not widening distally; basis of pereopod 6 strongly widening distally to broad anterior lobe. Pereopod 7 basis nearly circular, posterior edge with a few shallow indentations, each with a tiny setule, medial surface with a few tiny simple setae, propodus about half as long as carpus. Pereopods 5–7 basis anterior margin with 1 or 2 tiny robust setae.

Uropods 1 and 2 reaching to the end of uropod 3 peduncle, rami of both of subequal length, with a few dorsal setae. Uropod 3 peduncle approximately half as long as outer ramus, rami reaching just beyond apex of telson; outer ramus with a few dorsolateral (robust) setae; inner ramus marginally shorter that outer; with dorsal row of long setae.

Telson as long as uropod 3 outer ramus but not reaching its apex; presumably deeply split according to the statement “each of its halves has three groups of dorsal bristles and one terminal group.”

Size. ♂, 4 mm. ♀ not known.

Distribution. West Africa, off Guinea; 45 m.

Figures

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).

FIGURE 11. Tironella altifrons (Reid, 1951) comb. nov. Holotype, ♂. gp1, gnathopod 1 basis; gp2, gnathopod 2; md, mandible; mx1, maxilla 1 with op, outer plate and plp, palp; pl1, pleosomite 1 dorsoposterior margin.