Wednesday, 30 September 2015

Burmargiolestes cf. laidlawi

Last weekend I wanted to escape the gloom of Hanoi and flew down to Da Nang, from where I went to the area around P'rao along the Ho Chi Minh Highway in Quang Nam Province. This is quite an interesting area with some reasonable remaining forest and a few interesting streams. It was here that I trotted through a stream for two consecutive days, during which I added a few species to my Vietnamese list. It was a bit cheeky, as this is outside my normal area of research (too far south), but it provided a lot of interesting insights. Anyway, on the second day I was searching for the female of an as yet, presumably, undescribed Coeliccia species when I noticed on a very wet slope just above the stream a Burmargiolestes male hiding amongst the roots. Interestingly, it did not have the whitish rings at the tip of the abdomen of B. melanothorax and it also seemed to have rather extensive pale sutures on the thorax. I was able to catch it and in hand noticed an additional and exciting feature. It had a pale blue face! Now, B. melanothorax (and rather similar Argiomorpha fusca) has an ochre face. This clearly was something else. Checking the literature at home it dawned that the species described as B. melanothorax by Selys and illustrated in Fraser (1933) had been shown by Lieftinck (1960) and Asahina (1985) to be a different species, B. Laidlawi, that differed for instance in the pale blue face. This species occurs in India.

Rory Dow alerted me to the fact that similar specimens had been recorded in Vietnam before. Actually from Bach Ma National Park, close to Da Nang, by Matti Hamalainen. And Haruki Karube also mentioned having recorded it. So in the south of Vietnam there is a species with a pale blue face and mine is not just an aberration.

Interestingly, the description in Fraser mentioned that the pale blue extends to the base of the antennae, exactly like in my specimen (the ochre of B. melanothorax extends only marginally unto the frons). Rory mentioned that there are some small differences between the specimens of B. laidlawi from India and those from around Da Nang, for instance by displaying a pale area on S9. This is mentioned also by Asahina. However, the description by Fraser mentions only "Abdomen glossy black or blackish-brown in subteneral specimens, segments 3 to 6 with an obscure yellowish spot or annual near the base." He says noting about a pale area on S9. I have not been able to find any photo or further useful illustration of the species and therefore think it is perfectly possible that the species in Vietnam is in fact B. laidlawi. Nevertheless, given the long distance between it known range and Vietnam, it is better to consider this B. cf. laidlawi until a direct comparison with Indian laidlawi is possible. 

Male Burmargiolestes cf. laidlawi. Note the pale lateral lines on the prothorax, the pale line at the dorsal end of the thoracic sutures and the all dark S8-10. 
Slightly overexposed face of the same male. The pale blue extends well beyond the base of the antennae and up to the central ocellus. This is much more extensive than in B. melanothorax.

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