Ubristes Walker 1852

Abstract

Ubristes Walker, 1852 Ubristes Walker, 1852: 217. Type species: Ubristes flavitibia Walker, 1852: 217, by original designation. Differential diagnosis. Species of Ubristes have the scutellum without calcars and long, brush-like pilose metatibia and metabasitarsomere, with pile longer than the width of the tibia (Fig. 9). Among the genera with this diagnostic pilosity of the metaleg, Ubristes is the only one in which tergite 2 bears a lateral tubercle on both sides at approximately half its length (Fig. 1). The male genitalia are unique among all Microdontinae because of the presence of well-delimited, oval pits on both sides of the epandrium (Figs 11–13), named fenestrae (Reemer and Ståhls 2013 b). In the hitherto described species of Ubristes, the wing vein R 4 + 5 has a posterior appendix (spur or additional vein) into cell r 4 + 5, a character also found in many other microdontine genera. In Ubristes mirabilissimus sp. nov., however, this appendix is absent (Fig. 3). Consequently, our new species would probably run to Hypselosyrphus Hull, 1937 in the keys to the genera in Reemer and Ståhls (2013 a) and Reemer (2014). All Ubristes species differ from Hypselosyrphus, as well as from all other microdontine genera, by the presence of lateral tubercles on tergite 2. Distribution and ecology. Known localities of all species of Ubristes are indicated on the map of South America in Fig. 14, based on the label information as published by Reemer (2013 a, 2017) and this study. The number of localities per species is very low (two at maximum), so the distribution patterns are undoubtedly very incomplete. Reemer (2017) discussed the little amount of available information about the ecology of the other Ubristes species, and it seems that Ubristes species occur in tropical rainforests. Ubristes mirabilissimus sp. nov. is not an exception, as both known localities are located in Ecuadorian parts of the Amazon rainforest.

Authors 2

1. Menno Reemer Aachen Naturalis Biodiversity Center

   Naturalis Biodiversity Center · Instituto Nacional de Biodiversidad

   Affiliation as printed

   Naturalis Biodiversity Center, P. O. Box 9517, 2300 RA Leiden, Netherlands & Instituto Nacional de Biodiversidad, Quito 170135, Pichincha, Ecuador

2. Ximo Mengual

   Zoological Research Museum Alexander Koenig · Leibniz Institute for the Analysis of Biodiversity Change · Instituto Nacional de Biodiversidad

   Affiliation as printed

   Instituto Nacional de Biodiversidad, Quito 170135, Pichincha, Ecuador & Museum Koenig Bonn, Leibniz-Institut zur Analyse des Biodiversitätswandels, Adenauerallee 127, 53113 Bonn, Germany