Drymeia Meigen 1826

The genus Drymeia Meigen, 1826

Drymeia Meigen, 1826: 204. Type-species: D. obscura Meigen, 1826 [= Musca hamata Fallén, 1823], by monotypy. Gender: feminine.

For a full list of generic synonyms, see Savage & Wheeler (2004).

Drymeia is a well-defined and monophyletic genus of the tribe Azeliini, subfamily Azeliinae. Cladistic morphological analysis has shown that its sister-group is the small Central Asian montane genus Xestomyia Stein, 1907, and that Drymeia + Xestomyia is the sister-group of Azelia + Thricops (Savage & Wheeler 2004). A more recent molecular analysis (Kutty et al. 2014), however, suggested that Drymeia is the sister-group of Hydrotaea Robineau-Desvoidy, and that Drymeia + Hydrotaea is the sister-group of Thricops + Huckettomyia (maximum likelihood tree); Azelia and Xestomyia were not included in this analysis.

Drymeia as currently recognised includes species of Azeliini with 3 or more posterodorsal setae on the hind tibia. Further diagnostic characters are (partly from Savage & Wheeler 2004): gena usually relatively broad with a patch of numerous but fine upcurved genal setae; genal dilation often extending anteriorly, convex and prominent; posterodorsal surface of hind coxa bare; hind tarsomere 1 often with a strong ventral seta near base; fore and mid tibiae with 1 or more setae on the ventral surfaces; haltere black; female frons with a pair of crossed setae on frontal vitta (except in tetra (Meigen)) and with the lower orbital seta proclinate and, usually, exclinate.

Species of Drymeia are invariably black in colour, with varying amounts of grey or brownish-grey dusting. Males have striking collections of setae and hair-like setae on the mid femur, hind femur and hind tibia, and this armature is highly species-specific. The male hind tibia often has an apical ventral prong that may be short and inconspicuous or long and almost as long as the apical tibial width. Xue et al (2009) have given an interesting discussion of several morphological modifications of Drymeia species which they suggest may be adaptations to the harsh environmental conditions at high altitude. These include the slender elongated mouthparts which facilitate the search for nectar and pollen whilst the flies are creeping among the sheltering petals of flowering plants, the streamlined body form, the specialised setae and setulae including the apical ventral projection on the hind tibia, the pointed and inwardly-directed projection on the inner surface of the male surstylus, and the fusion of the paired rods of tergite 8 in the female oviscape which increases the rigidity and tension of this organ during copulation and oviposition.

The plasticity in characters which are striking, autapomorphic developments or which have in the past been considered to be of generic value has led to the erection of a number of genera which were eventually all synonymised with Drymeia, the oldest name in this group of genera (Pont 1986; Huckett & Vockeroth 1987). These include:

Drymeia itself, which until 1986 contained only one species with a highly modified proboscis in which the labella are long, slender, strongly sclerotized and normally doubled back.

Bebryx Gistl, 1848, with fine setulae on the anepimeron and males with the tip of the abdomen enlarged and bearing a dense brush of slender black setae and setulae, caudally directed.

Pogonomyia Rondani, 1871, with facial edge projecting forward beyond the level of profrons.

Eupogonomyia Malloch, 1921, with a short prealar seta.

Pogonomyioides Malloch, 1919, with fine setulae present on katepimeron and apex of male fore coxa prolonged into a knob-like structure.

Trichopticoides Ringdahl, 1931, with facial edge not projecting forward beyond the level of profrons and eye in male densely haired.

Neoeriphia Schnabl & Dziedzicki, 1911 and Neopogonomyia Schnabl & Dziedzicki, 1911 have not been accepted since their original descriptions.