Burmochlus gen. nov., the first Cretaceous member of the Archaeochlus cluster (Diptera: Chironomidae: Podonominae)

Abstract

A fossil genus, Burmochlus gen. nov., with a species B. madmaxi sp. nov. (Diptera, Chironomidae, Podonominae) is described from mid-Cretaceous amber of northern Myanmar (~100 Ma). The adult male of the new species/genus displays an interesting wing structure with a trace of the vein R2+3 (or R3 alone), the character unique in the subfamily Podonominae. The wing squama with a process bearing a bunch of setae, the wing membrane covered with bi- or trifid spinulae-like microtrichia, the gonostylus with a collar-like ring and a pear-shaped distal part, the robust anal point and the extensive superior volsella are also characters defined as exclusive for Burmochlus. The antenna, thorax and several hypopygium structures found in male Burmochlus clearly resemble those known from Archaeochlus Brundin, here defined as the closest relative, as well as from Afrochlus Freeman and Austrochlus Cranston – both previously referenced to or derived from Archaeochlus, hence being postulated as close or sister taxa. In a view of several hypotheses on the time of divergence of the Podonominae and other related subfamilies, this is the oldest fossil record of a true Podonominae chironomid based on definition of male characters, and dated back to the “mid-Cretaceous”. Along with Furcobuchonomyia Baranov, Góral et Ross (Buchonomyiinae) and Myanmaro Giłka, Makarchenko, Pankowski et Zakrzewska (Orthocladiinae), Burmochlus is the third genus described from Burmese amber, and the first known Podonominae chironomid described from this deposit.