Tuesday, 2 June 2015

Two new and two old Anotogaster species

The last few weeks have been pretty productive where Anotogaster species are concerned. And these giants are a always a treat. They are big, bold and beautiful. They are also pretty confusing, with at least 5 different species occurring in northern Vietnam, all of which for instance occur around Sa Pa and often several species are present at the same streams (see also the very useful introduction on Vietnamese Anotogaster species by Haruki Karube).

Until now I had observed A. sakaii, the largest species, A. klossi and A. gigantica (the smallest, intriguingly). This year I again saw A. sakaii. On May 3 we observed a male on mount Mau Son in Lang Son Province, on May 20 I saw it in Pia Oac in Cao Bang Province and on May 25 I saw one at the Love Waterfall area in Sa Pa.

But on May 17 I also caught a smaller species in the Sa Pa area. This turned out to be A. chaoi. This somewhat smaller species resembles A. sakaii in that it has orange bases to its mandibles. But it is, as said, significantly smaller, with a deeper excavated frons and different appendages. On May 25 I saw at least 3 males at Sa Pa, and also a female. (There is some confusion about A. gregoryi, a species recorded from Thailand, that may have been confused with A. chaoi).

The male Anotogaster chaoi. Note the orange mandible base.
The face of the male in frontal view, showing the deeply excavated frons (relative to A. sakaii)
The female of A. chaoi, sharing the same pattern of the face and the small yellow lines along the posterior edge of S2.
The face of the female
Appendages of the male in dorsal view
And in lateral view

On May 25 I also found a freshly emerged male at exactly the same spot where a week earlier I had caught my first A. chaoi. But it was immediately clear that this fresh specimen was a different species, the magnificent A. sapaensis. Magnificent, because it has an all orange face, very different from the other 4 species known from Vietnam. This feature makes it easy to recognize. Other characteristics, like the shape of the appendages help verify the ID. After all it cannot be ruled out that there may still be undiscovered species about, so this check is necessary.

Against the unattractive background of discarded plastic the very attractive fresh A. sapaensis, right next to its exuvia.
The face in close-up, all unmarked orange brown 

On May 31 I caught my fourth species of this year at Pia Oac. This was A. klossi, which I had found there before. Like A. gigantica it has yellow bases to the mandibles, helping to separate it from A. sakaii and A. chaoi. A. klossi is a large species, close to A. sakaii, with the male being about 10 cm. It differs from A. gigantica not just in size, but also in the abdominal pattern, which is much reduced and more orange red ventrally.

Scan of the male A. klossi, with the much reduced banding on the abdomen, turning orange red ventrally.
The face of the same male, with the bright yellow mandible bases


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