Sunday, 2 December 2007

Cataglyphis oasium

The size of an ant and how easy it is to identify are not necessarily related. Whilst Monomorium mictile, at just over 1 mm, was relatively easy to identify, I'd been pondering this very large species of Cataglyphis for weeks.

Cataglyphis is a genus that is taxonomically muddled. I've finally concluded that this species is probably Cataglyphis oasium. It was the keys in Santschi (1929) and Radchenko (1998) that eventually provided the most likely identification.

C. oasium was originally described by Santschi (1929), though the name he gave it (Cataglyphis bicolor st. nodus v. oasium) was invalid, so the authority for this species is Menozzi, 1932. Menozzi only gave two lines of text to the species, changing the name to Cataglyphis bicolor var. oasium, without noting that it was a new combination or providing a fresh description, and naming Santschi as the authority. The variety oasium was later given subspecies status and then species status by Radchenko (1997). Wehner, Wehner & Agosti (1994) suggested that C. bicolor subsp. oasium was synonymous with Cataglyphis savignyi, though they didn't actually synonomise the two names. Thus, the valid name is C. oasium. It's very confusing, so it took a little while just to sort out this history.

Information on the distribution of C. oasium is very sparse. Santschi mentions records from Tunisia and Algeria, whilst the most recent record that I'm aware of is Libya in 1931, which is reported by Menozzi. Radchenko (1998) states that it is found in North Africa and the Middle East.

This gives the impression that C. oasium is rare, but this seems unlikely. It is probably under-recorded due to the taxonomic difficulties. It is possible that the species collected by Lenoir and mentioned in The Ants of Africa is also this species. If C. oasium is found in oasis in the Sahara and in the Middle East it seems reasonable that it could also occur in The Gambia and Burkina Faso.

The Gambian specimens were collected from Kololi and Madiyana Camp on Jinack Island, mainly from sandy ground in scrub savannah. In this sort of hot scrub savannah it could be quite common, so it may be abundant further inland, away from the coastal breeze.

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