Minitiron, 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 : 78

Key to species of Minitiron gen. nov.

1. Maxilla 1 palp reduced, half-length of outer plate, with a single simple seta; inner plate narrow, pointed, nearly as long as outer plate, with spaced row of small setae along medial margin; mandible with long simple seta in place of palp................................................................................................ M. bellairsi ( Just, 1981)

- Maxilla 1 palp reaching to about apex of outer plate setal spines, with a few apical peg-like setae, inner plate stout, subequal in length to outer plate, with a few apical setae on apex, mandible without seta in place of palp.......................... 2

2. Maxilliped outer plate concave medially to pointed apex...................................................... 3

- Maxilliped outer plate with normal truncate or rounded apex................................................... 4

3. Coxal plate 1 twice as long as broad, anterior margin broadly pointing in middle, rounded distally; pereopod 7 basis posterior margin evenly convex with regular crenation.............................. M. galeatus ( Hirayama, 1988) comb. nov.

- Coxal plate 1 about 1.5 longer than broad, widest distally, anterior margin nearly straight............................................................................................... M. thompsoni ( Walker, 1904) comb. nov.

4. Head lateral front lobe rounded truncate; coxal plate 1 anterior margin broadly rounded; coxal plate 3 distal half widening to near twice width of proximal half, with rounded anterodistal projection........... M. caecus ( Ledoyer, 1979) comb. nov.

- Head lateral front lobe pointed or rounded right angle; coxal plate 1 anterior margin not broadly rounded; coxal plate 3 anterior margin straight, posterior margin with projection in distal half.................................................. 5

5. Maxilla 1 inner plate margins parallel, apex blunt with 3 pectinate setae; coxal plate 1 wide-angle rounded, anterior margin with broad 90% triangular projection; coxal plate 3 with angular, slightly crenate posterior margin and midposterior projection; pleonites 1–3 posterodistal corners acute................................. M. ovatibasis ( Hirayama, 1988) comb. nov.

- Maxilla 1 inner plate tapering, apex blunt with a few setae; coxal plate 1 anterior margin straight; coxal plate 3 midposterior projection broadly rounded wide-angled; pleonites 1–3 posterodistal corners rounded................. M. orpheus sp. nov.