Glandulotiron meruspinosus, 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 : 52-55

Glandulotiron meruspinosus sp. nov.

( Figs 29–30 )

Type fixation. Holotype, ♀.—Here designated.

Etymology. This is the only species in the genus with robust setae in a row on the posterior margin of gnathopod 2 merus.

Material examined. Holotype, ♀, 7.6 mm. Australia, New South Wales, Twofold Bay off midpoint of Aslings Beach , 37˚05’S, 149˚56’E, 33 m, small dredge, S.J. Keable & E.L. Albertson, stn E174, 21 February 1985, AM P36039.

Paratypes. Same data as holotype, AM P105642 (1 juvenile). Australia, New South Wales, east of North Head, Port Jackson, 33°49’30”S, 151°18’E, 43 m, Australian Museum Party , 24 May 1972, AM P23996 (19 specimens). Australia, Tasmania, Eastern Bass Strait , 94 km NE of North Point, Flinders Island , 38˚53’42’’S, 147˚55’06’’E, 58 m, coarse shell, epibenthic sled, RV Tangaroa , stn BSS176 , 18 November 1981, NMV J73753 (3 specimens). Australia, New South Wales, east of North Head, Port Jackson , 33°49’30”S, 151°18’E, 43 m, Australian Museum Party, 24 May 1972, NHMD 916116 (3 specimens) .

Description. Head dorsal surface smooth. Rostrum broadly rounded triangular. Interantennal lobe slightly concave, lower corner larger than upper and right angled as opposed to wide angled upper corner. Accessory eyes composed of 4 ommatidia.

Mouthparts. Maxilla 1 palp apex with 1 pointed lateral seta and 5 short, broad micro-dentate setal spines (observed, not illustrated). Mouthparts otherwise normal.

Antenna 1 as long as pereonites 1–5 combined along dorsum, peduncle article 2 about 0.6 length of article 1, article 3 about 0.7 length of article 2, article 1 with 3 penicillate setae ventrally and two middorsally; flagellum slightly longer than peduncle, of 8+ articles; accessory flagellum of 4 articles. Antenna 2 slightly longer than pereonites 1–7 combined along dorsum, peduncular article 4 the longest; flagellum of 6+ articles, most articles with single slender, curved robust seta dorsodistally; antenna otherwise sparsely setose.

Coxal plates 1–4 distally fringed with several long setae, otherwise smooth.

Gnathopods 1 and 2 of subequal length. Gnathopod 1 basis with several long and a few short setae posteriorly and a few long and short setae on anterior margin, merus with simple long and short setae on posterior margin, carpus with a few long setae on anterior margin, posterior margin with about 8 groups of long and shorter setae, mostly finely pectinate setae, propodus with a row of 5 stout pectinate setae on posterior margin, dactylus with unguis 1/2 length of propodus, nearly straight. Gnathopod 2 basis with few unequally long setae on anterior margin, and row of longer setae on distal half of posterior margin, merus posterior margin with 3 strong, robust setae and 1 or 2 simple setae between the anterior 2 robust setae, carpus with a few long setae on distal margin, posterior margin with about 8 groups of long and shorter setae, propodus with long, simple setae on anterior margin and a few simple setae on posterior margin.

Pereopods 3–4 basis, ischium, merus and carpus with a few simple marginal setae, propodus with stout anteroterminal robust seta.

Pereopod 5 basis posterior margin straight, posterodistally with moderately extended rounded lobe, anterior margin with a few long simple setae proximally and some tiny setae more distally, ischium and merus with few small simple setae, merus with long robust seta posterodistally and tiny robust seta anterodistally, carpus with single robust seta posterodistally and row of 3 robust setae in anterodistal margin, propodus with 3 robust setae of varying length posterodistally. Pereopod 6 basis narrow ovoid with shallow posterodistal lobe, anterior margin with long setae and a few short ones, remaining articles as in pereopod 5 with a few more setae. Pereopod 7 basis much broader than in 5 and 6, with large, broadly rounded posteroproximal lobe, posterodistal corner rounded, hardly projecting, mid-medial surface with several long setae, anterior margin with short group of setae in middle and in distal corner, ischium anterior margin with distal tuft of long setae, merus as in pereopod 6 with a few more small anterior robust setae, carpus longer than in pereopods 5 and 6 relative to propodus, posterior margin with single robust setae distally, anterior margin as in pereopod 6 but more spaced robust setae, propodus as in pereopods 5 and 6.

Uropod 1 peduncle reaching to end of peduncle of uropod 2, rami of equal length, about 2/3 length of peduncle, overreaching rami of uropod 2 with about 1/3 their length. Uropod 2 rami reaching to about 1/3 along uropod 3 outer ramus, inner ramus slightly longer than outer ramus. Uropod 3 peduncle slightly more than half as long as outer ramus, rami elongate oval, reaching beyond apex of telson, outer ramus basal article with row of 9 robust setae dorsally, and 4 small robust setae ventrally, small second article with 3 dorsal robust setae; inner ramus as long as 4/5 of basal article of outer ramus, dorsal margin with row of long setae and 2 robust setae, apex with 3 robust setae.

Telson. Length about 3.5 times greatest depth in lateral view, reaching 0.6 along outer ramus of uropod 3, length/dorsal width approximately 2.0, with row of 4–5 robust setae, small simple setae and a group of 2 plumose seta dorsally on each lobe, apices with 1 long and 1 short robust seta.

Size. Largest ♀ 7.6 mm. Largest ♂ 10.2 mm.

Distribution. Australia, New South Wales to Bass Strait, 58 m.

Figures

FIGURE 29. Glandulotiron meruspinosus gen. et sp. nov. Holotype, ♀. clv, head lateral view; gp1 and gp2, gnathopods 1 and 2; tel, telson dorsal view; us, urosome; arrows, diagnostic robust setae.

FIGURE 30. Glandulotiron meruspinosus gen. et sp. nov. Holotype, ♀. cox3, coxal plate 3; p4–p7, pereopods 4 to 7.