Tironinae, 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 : 8

Key to the genera in Tironinae

(See also Fig. 1 )

1. Pereopods 3–7 dactylus short, with curved robust seta countering short curved unguis, (pre-stubby, Fig. 1 b )............. 2

- Pereopods 3–7(6) dactylus and unguis strongly modified and complex, with curved robust seta countering modified unguis, (stubby, Figs1a , 38x ).................................................................................. 3

2. Head in lateral view evenly curved to downward pointed acute rostrum, eyes and accessory eyes present, coxal plate 3 rectangular, uropod 1 outer ramus of single article, reaching well beyond uropod 2..................... Tiron Lilljeborg, 1865

- Head in lateral view with anterior front rounded, dorsal and anterior margins straight, at right angle; rostrum apex sharply pointed at 90° angle; interantennal lateral head margin with about 100° blunt projection; coxal plate 3 widening distally to broadly rounded apex and slight posterodistal concavity; uropod 1 barely reaching end of uropod 2, uropod 3 outer ramus of single article........................................................................... Tironella gen. nov.

3. Mandible palp present; uropod 3 outer ramus with small article 2, uropod peduncles, and telson with rows of elongate glands....................................................................................................4

- Mandible palp absent; uropod 3 outer ramus of single article, urosome without glands............................... 5

4. Mandible palp article 2 straight; coxal plates 3–4 pelagont (see key to family, notes and Fig.1 ).. P s eudotiron Chevreux, 1895

- Mandible palp article 2 curved, coxal plates 3–4 similar, not pelagont......................... Glandulotiron gen. nov.

5. Gnathopod 1 basis straight ( Fig. 43a ), maxilla 1 outer plate with broad oblique row of spine-setae ( Fig. 43b )......................................................................................... Metatiron Rabindranath, 1972

- Gnathopod 1 basis strongly curved ( Fig. 43c ), maxilla 1 outer plate with narrowly amassed group of elongate, apically curved spine-setae ( Fig. 43d ).................................................................... Minitiron gen. nov.

Figures

FIGURE 1. Representative habitus illustrations of tironin genera. Tiron spiniferus (from Sars, 1895 pl. 140, ♀ 8 mm); Pseudotiron miratus sp. nov. (this paper, ♀, 4.5 mm); Tironella pervicax comb. nov. (from J.L. Barnard, 1967 fig. 84, ♂ 4.7 mm); Glandulotiron pilocaputis sp. nov. (this paper, ♀, 6.3 mm); Metatiron tropakis (from J.L. Barnard, 1967 fig. 45, ♀, 4.9 mm); Minitiron bellairsi comb. nov. (from Just, 1981 fig. 1, ♀ 2.4 mm). a and b, dactylus and unguis of pereopods 3–7: a, stubby; b, pre-stubby.

FIGURE 38. Glandulotiron griffithsi gen. et sp. nov. Holotype, ♀. gp1–2, gnathopods 1 and 2; p3, pereopod 3; p5–7, pereopods 5–7 (5 broken distal to carpus); s, heavily plumose setae; x, pereopod 6 apex of propodus with stubby dactylus.

FIGURE 43. Principal characters separating Metatiron and Minitiron gen. nov. Upper row, gnathopod 1; lower row, maxilla 1 outer plate. a and b, Metatiron tropakis, original; c and d, Minitiron bellairsi, c from Just 1981; d, from Barnard & Thomas 1989.