Minitiron thompsoni ( Walker, 1904 ) 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 : 82

Minitiron thompsoni ( Walker, 1904) comb. nov.

Tiron thompsoni Walker, 1904, p. 263 –264, pl. 4, figs 21.

Tiron thompsoni .– J.L. Barnard (1972, p. 83); Jazdzewski (1990, p. 118); Barnard & Karaman (1991, p.717); Lörz & Coleman (2013, p.126); Cadien (2014, p. 11).

Type fixation. Holotype, ovigerous ♀.—By monotypy, (not seen).

Distribution. Sri Lanka [ Ceylon], south of Colombo, Kondatchi Paar, Stn LXVI (‘ 1 female with ova’).

Remarks. The placement of this species in Tiron has never been reviewed, mostly because of the few and rather poor illustrations. Since its description ( Walker 1904) Tiron thompsoni has appeared in the literature mainly in keys to Tiron , separated out on account of an unusual outer plate of the maxilliped. The present review of the tironins makes it possible to compare this species with others in the currently recognised genera.According to Walker (1904) the species has a short, moderately curved and distally widening gnathopod 1 basis similar to species in Minitiron , contrasting with the elongate, straight gnathopod 1 basis of equal width throughout found in all other tironins. Furthermore the species has stubby pereopods 3–7 (although poorly illustrated), and unusual, concave maxillipedal outer plates closely similar to Minitiron galeatus from Japan. Although many details remain to be learned about Walker’s Tiron thompsoni , notably the type of setal spines on the outer plate spine-row and shape and size of the inner plate of maxilla 1, the species is here tentatively transferred to Minitiron .