The world of Protosticta

Once you start looking at Protosticta species, you will find there is a whole world out there! Only recently I published a paper with Toan giving details on the currently known 9 species from this genus for Vietnam. Two of these are large and different: Protostica grandis and P. ngoai. One has very typical appendages: P. spinosa. The remaining 6 are very similar. I had not yet seen several of these, but on May 5 in Quang Tri province I found an area where I kept bumping into one of these: P. caroli (first described by Jan van Tol in 2008). It can be identified by the only partially pale S9, the stubby inferiors (compared to for instance P. socculus) and the prothorax of which always the posterior lobe is extensively dark, which extends onto the central lobe. But really one needs a microscope to settle its identity for sure.

In the same area, but on a drier slope, I ran into what seemed a "very" different species. A little smaller, it was crispier, in that the white rings on the abdomen were really white, the prothorax had only on oval black spot in the posterior lobe, it has all white S9 and under the microscope there are also important differences in the appendages (like a missing lobe). Careful checking at home showed it was none other than P. socculus.

Relatively boring P. caroli. It shares with P. socculus the broad black line over the metapleural suture. S9 is only two-thirds pale, but not truly white, and the abdominal rings are likewise not very crisp.

Another specimen, similarly with limited white on S9.

A male in hand. This specimen has minimal dark markings on the prothorax, but still all dark posterior lobe, dark extending onto central lobe in two triangles, remainder off-white. The colour of the thorax is a dull dark green. 

P. socculus. Note the very white abdominal rings, the crisp white prothorax with contrasting posterior lobe

A close-up of the prothorax. Note also that the colour of the thorax is a different green.