This little Carcelia-like tachinid stood out from the rest of the Carcelia and Houghia spp. because the dusting was very different and the humeral callus had bristles arranged in a line. I have made a slightly tentative identification of Argyrochaetona sp. because it runs very well to this genus in Monty’s key (even up to the wavy dusting pattern on T4), but of course French Guiana is outside the normal range of his keys so there is always the possibility that this is something else.
Two spp. have been described – one from Cuba (cubana Townsend, 1919) and the other from Peru (peruana Townsend, 1928) but Townsend’s type descriptions are usually “less than adequate”, to put it politely, so it is very hard to be sure whether this is either of them … we need the types, wherever they might be! His type descriptions are quoted below.
This specimen comes from French Guiana so I conclude that, if it is an Argyrochaetona, it is either a new species or it extends the known range of an existing Argyrochaetona by quite a long way! 🙂
Townsend 1919: Argyrochaetona, new genus.
Genotype, Argyrochaetona cubana, new species.
Clypeus well depressed. Epistoma full width, cut off short. Palpi short, much broadened and flattened apically. Eyes bare, descending nearly to lower border of head. Male vertex less than half eye, parafrontalia meeting over frontalia in middle. Frontals descending one bristle below base of antennae. Parafacialia very narrow, bare. Male with two very strong fronto-orbitals, the anterior one reclinate; and one or two weak rec-linate ones behind. Ocellars very weak. Preacrostichals present. Apical cell open considerably before tip. First two abdominal segments with a median marginal pair, that of first weak; last two segments with marginal row.
Argyrochaetona cubana, new species.
Length, 6 mm. One male, Santiago de las Vegas, Cuba (P. Cardin).
Face and front silvery-white. Frontalia brown. Antennae blackish, second joint and base of third pale rufous. Palpi fulvous. Mesoscutum, scutellum and abdomen pale golden pollinose over black, leaving four vittse on first; all of first abdominal segment and broad hind borders of other segments black. Legs brown. Tegulae watery-whitish. Wings clear.
Townsend 1928: Argtrochaetona peruana, n.sp. – Bl, 6mm; wl, 5mm. 1 male, Cartavio, Trujillo, Peru, June 5, on herbage bordering sugarcane.
Differs from A. cubana by male frl quite covered anteriorly as well as posteriorly by pfrl, latter almost contiguous from oct to ln; male vrw 1/4 hw, fr faintly narrowed anteriorly but over 1/5 hw at ba, 1 quite strong rfro; 3 strong pa, aps dec & moderately strong but short, R5 with 3 brs extending not over 1/5w to R6, narrowly open 2 x mw before wt, M3 its length from cb, quite strong mm pr on 1sg; pollen of whole upper parts pale golden including vr, octh, ind portion pfrl & uoo; 4 equal narrow black thv, ab rufous on sides, 1 blackish.