Psilotarsus brachypterus brachypterus (Gebler, 1830)

Karpinski, Lech, Szczepanski, Wojciech T., lewa, Radoslaw, Walczak, Marcin, Hilszczanski, Jacek, Kruszelnicki, Lech, Los, Krzysztof, Jaworski, Tomasz, Marek Bidas, & Tarwacki, Grzegorz, 2018, New data on the distribution, biology and ecology of the longhorn beetles from the area of South and East Kazakhstan (Coleoptera, Cerambycidae), ZooKeys 805, pp. 59-126 : 63

Psilotarsus brachypterus brachypterus (Gebler, 1830) Figs 1 A–C, 9 A–E

Material examined.

East Kazakhstan Region: 8 km NW of Kurshim [ Күршім] (48°37'N 83°35'E), 462 m a.s.l., 17 VI 2017, 127♂♂, 6♀♀, leg. MW; 52♂♂, 5♀♀, leg. LK; 114♂♂, 7♀♀, leg. WTS; 31♂♂, 3♀♀, leg. MB.

Remarks.

This taxon is distributed in the easternmost part of Kazakhstan (the Irtysh River valley - from the environs of Semei to the Zaisan Depression) and northwestern China (Xinjiang and possibly the Gansu Provinces) ( Danilevsky 2000, 2018a).

The nominotypical subspecies differs mainly due to the shorter lateral process of each middle antennal joint (generally much shorter than the length of joint base) and to its glabrous and shining pronotum, which is situated peripherally, and is rarely covered with a more or less dense pubescence ( Danilevsky 2000).

The mass occurrence of this taxon (approx. five hundred specimens) was observed in mid-June during warm (25 °C) weather conditions in the Artemisia -desert habitat (Fig. 9F). This period most likely coincided with the beginning of the appearance of females (Fig. 9B) when the males (Fig. 9A, D) were about to reach maximum abundance. The first flying male was spotted immediately after our arrival at this plot (around 9 p.m.), and therefore, it is possible that this taxon begins its activity a little earlier. The number of individuals was increasing after dusk and reached its peak around midnight (Fig. 9D). At the same time, the females were found resting or moving on the ground. They did not seem to react to the light source in any way, even from very close distance. The females were much less numerous (ratio of approx. 1:20) and barely 20 specimens were collected during a few hours of searching within a radius of approx. 800 m from the light source. They appeared to stay active most of the night. Although no mating couples were spotted, a few probably still virgin females were observed resting motionlessly and attracting the males by rising and swinging with their ovipositor exposed in order to shoot out and spray a cloud of pheromones (Fig. 9C). A similar behaviour was observed by Danilevsky (2000) in the case of Psilotarsus turkestanicus (Semenov, 1888) in the Samarkand environs in Uzbekistan.

It is worth noting that quite a significant portion of the individuals were found dead or still alive in the webs of the Mediterranean black widow spider Latrodectus tredecimguttatus (Rossi, 1790) (Fig. 9E). In some places, the density of these arachnids reached a few individuals per m2 and the specimens of Psilotarsus (both males and females) were the main victim of this spider species. Therefore, it seems that the hunting activity of L. tredecimguttatus is among the most important factors that affect the population of this beetle.