ChrisR

This is a little post just to show the range of antennal branching in different multifissicorn tachinids – apologies for the poor quality of the photos.

As you can see, Cryptocladocera spp. have huge branches on their antennae while both of the 2 new species have much shorter antennal branches, which seems closer to the description of Cerotachina. Personally, I would like to lump them all into Cryptocladocera but I need to do more research first.

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This appears to be another new, hitherto undescribed, species closely related to Cerotachina - it has no median discals and antenna-3 is very shallowly multifissicorn. That is, the third antennal segment has bumps on both sides covered with tufts of long hairs.

These bumps are shorter than the branches on my French Guianan Cerotachina and a lot shorter than the branches on my French Guianan Cryptocladocera but it clearly displays an early step in an evolutionary process that finally arrived at the extremely long branches on the Cryptocladocera.

It might be tempting to split this taxon into yet another genus (as Townsend would have done!), based on the short branches/bumps on the antennae. But I would prefer to actually remove Cerotachina Arnaud, 1963 and group everything under the genus Cryptocladocera Bezzi, 1923 (being the oldest valid name). My reasoning for this is that: the 2 genera have very similar morphology; have very similar male genitalia; and it is highly likely that other species will be discovered with more intermediate forms of antennal morphology.

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This little gem is another multifissicorn species with feathered antennae – similar to the other ‘featherface’ tachinids, like Borgmeiermyia and Cryptocladocera. However, after running this through Arnaud (1963) it keys out as Cerotachina but doesn’t conform to either of the 2 known species so I am considering this a new, as yet undescribed species.

In summary, this species keys to Cerotachina because it has no median discal bristles the branches on antennae-3 are short – much less than 1/3 the length of antenna-3. The 2 existing species (C.elegantula & C.albula) are described as having a black body and black femur with darkened tibiae but this species has a dark-brownish ground colour (especially on the pleurae) and wholly bright orange legs.

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This is one of my favourite French Guianan tachinids! At first glance it looks fairly standard but when you examine the face you will see that antennal segment 3 (normally rectangular) has been formed into a feather-like structure, similar in design to moth antennae! This structure is recessed in a deep concavity in the face and fringed by a complete line of facial-ridge bristles.

I have nicknamed these ‘feather-face’ tachinids for my own personal reference but they are more properly called multifissicorn tachinids. The feature has only been found so far on males, which suggests that it is an adaptation for finding the females but this is just conjecture and is impossible to determine without a study of their lifecycles. The feature has been found on 2 taxa so far – the other being a tiny (4-5mm) taxon with a black body and golden dusting pattern on the thorax (fg-taxon #11 – Borgmeiermyia sp.).

EDIT (23/2/2010): After some investigations I found Arnaud (1963)* and the keys in there describe a few genera of multifissicorn tachinids (Cryptocladocera & Cerotachina). This taxon looks like Cryptocladocera (Cryptocladocera have branches on the antennae that can be 1/3 of the length of the antenna while Cerotachina should have branches of no more than 1/10 then length) but I am having difficulty tracking down any specimens to compare mine against. See also fg-taxon #97 (Cerotachina).

* Arnaud P.,H., (Jr) (1963) Systematic Studies in the Tribe Neominthoini (Diptera, Tachinidae). American Museum Novatates. number 2135 p. 1-55.

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