The Mysterious Amurian Grig Paracyphoderris erebeus Storozhenko, 1980 (Orthoptera: Prophalangopsidae): New Data on Its Distribution, Ecology and Biology

SIMPLE SUMMARY: The rare relict species Paracyphoderris erebeus is endemic to the Russian Far East. The primary objectives of this study were (1) to provide the unpublished data on habitat, behaviour and biology of the Amurian grig, (2) to discuss some issues arising from long-term studies of distribution, and (3) to produce ecologo-geographic models of the species distribution over the Far East as the basis to forecast some possible shifts in its distribution. Ecologo-geographic modelling of the P. erebeus distribution in 2021–2060 shows that the species range will be relatively stable. ABSTRACT: New data on distribution, ecology and biology of the rare extant species Paracyphoderris erebeus of the almost completely ancient family Prophalangopsidae (Orthoptera) are given. This montane species prefers humid areas with relatively low summer temperatures. Habits, mating behaviour and life history of P. erebeus are extremely similar to those of the North American representatives of the genus Cyphoderris. Nowadays, the Amurian grig is known from the Myaochan, Badzhalsky, Dusse-Alin, Bureinsky and Aezop ridges in the Khabarovsk Territory (north of the Amur River) and Bydyr Mountain in the Jewish Autonomous Region of Russia only. The analysis of the predicted distribution of P. erebeus based on the occurrence data reveals that the populations of the species may be more widely distributed over the southern part of the Russian Far East, at least up to 56° N. The ecologo-geographic model of the species distribution over its range is generated using the Maxent 3.4.4 software for the first time. Modelling of the P. erebeus distribution for 2021–2040 and 2041–2060 shows that the position of the species range appears to be relatively stable but a weak decline in the foretold suitability during climate warming may result in a reduction in population sizes and the subsequent fragmentation of the species population system. In this case, the Amurian grig will become a prospective to be included on the IUCN Red List.