Saturday, 13 February 2016

A new genus and a new species - Indolestes anomalus new for Vietnam

February 6 I had arrived in Cat Tien National Park for a 3 day field trip to work a bit with James Holden, who has been holed up there for half a year or so. We decided to work our way through the forest to visit two bits of streams that are running all year round, south of the grasslands. Hard work, as going off-trail means using GPS on working your way through bamboo. And those in the know are aware what that means. Our clothes were torn to shreds during the day, but we did see the two target Prodasineura species I really wanted to see. The first was P. doisuthepensis, a species that had been on my wish list for 2015, but I only saw it now. The other was the splendid P. hoffmanni, I already published on recently, with photos by James.

Anyway, while working our way through the forest I spotted a female Lestes with closed wings and took a quick swipe at it with my net. It looked different from anything we had seen before, although we considered it a possible Lestes elatus, a species we hardly ever, if at all, encounter. So forgive us if we failed to see immediately it certainly was not that.

What was striking in the specimen was not just the three separated markings on the mesepimeron, but also the very large ovipositor. The markings on the final segments were also not as expected of L. elatus. Later, at home, I took a closer look and noted the rather squarish pterostigmata. That set me onto the right course. The few photos of Indolestes anomalus (on Dennis Farrell's site for instance) were a good match and led me to the description by Fraser 1946 and reproduced in Asahina (1985). Wings match the original description (20mm), but abdomen was slightly larger (28.5 against 27mm). The original description is of a female. I am not sure whether the male is now known.

Indolestes anomalus is a rarely observed species, known from very few records of single specimens from Thailand only. It is good to see the species is more widespread, although the pattern of yet another single specimen from a relatively well researched area indicates it is indeed rare.

Female Indolestes anomalus. Note large bulging ovipositor, with brown S9. Top of head blackish green, three markings on the mesepimeron, the middle square, pattern of S1-2 and squarish pterostigma.
Close-up of the thorax, showing the pattern on the mesepimeron.

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