Did Cold Resistance Influence the Success of the Halobiont Darkling Beetle Centorus rufipes (Coleoptera, Tenebrionidae) During the Pleistocene?

<i>Centorus rufipes</i> (Gebler, 1833) is the only tenebrionid beetle commonly found in late Pleistocene deposits of southern western Siberia. It is assumed that the reasons for its success during the Last Glacial Maximum could have been its cold resistance and/or the relatively mild conditions of its habitat, the shores of salt lakes. The cold resistance parameters of <i>C. rufipes</i> and their overwintering conditions were studied near Kusgan Lake (Novosibirsk Oblast, Russia). Adults and larvae of this species used a supercooling mechanism to protect themselves from sub-zero temperatures and did not tolerate freezing, just like other steppe species of Tenebrionidae. The supercooling point (<i>SCP</i>) for most of the individuals was around -31 °C. Measurements of low lethal temperatures (<i>LLT</i>) showed that 50% of individuals died after 2 days of exposure to -27 °C. The measured <i>SCP</i> and <i>LLT</i> were at least 5 °C lower than darkling beetle species from the Chuya Depression of the Altai, which is known for its extreme winter temperatures. Thus, the hypothesis of increased cold resistance of <i>C. rufipes</i> was confirmed. No warming effect of its salt lakeside habitats was detected.