The phylogeny of the tribe Podonomini (Chironomidae: Podonominae) is clarified by new inclusion of Rheochlus Brundin in molecular analysis

Abstract

The immature stages of the patagonian podonomine (Diptera: Chironomidae) genus Rheochlus (Diptera: Chironomidae) have been unknown although the adult stage was described over half a century ago. New pupal associations with described adults belonging to two species of Rheochlus allow better understanding of the genus, its diversity and its phylogeny. The pupa of Rheochlus insignis Brundin is the same as an unreared damaged pupal taxon designated Podochlus sp. “Canteras’‘ by Brundin and is described more completely here. Inclusion of R. insignis in a molecular phylogenetic analysis shows it to be sister to two specimens (one a male, the other pharate female) allocated previously to Podochlus but better transferred to Rheochlus. The male morphology is compatible with Rheochlus prolongatus Brundin but we refrain from asserting identity by using ‘cfr.’ prolongatus to indicate the status. Molecular evidence also provides association of the female adult and pupa that are newly described here. We validate Rheochlus as distinguished on pupa and adult, with the type-species Rheochlus insignis from Patagonian Chile and Argentina, Rheochlus prolongatus Brundin from Southern Patagonia Argentina and possibly also from central Patagonia, Rheochlus latisetus Siri & Brodin from Patagonia, and the eastern Australia Rheochlus wirthi Brundin. The latter two species remain known only from their original adult male descriptions. Strengthened support for our concept of Rheochlus as a valid genus, sister group to Podochlus, derives also from an expanded and reanalysed morphological matrix.