Melanostoma

The description is based on Vockeroth (1992) and on own findings. Head: Eyes bare. Frontal triangle of male blackish, shining or with variable amount of dusting. Frons of female blackish, mostly shining with a pair of triangular dusted maculae above lunule. The size of these maculae varies and they are medially separated or confluent. Face and shallow facial tubercle blackish, shining or with a variable amount of dusting. Lunule black and shiny. Antenna varying from totally dark brown to largely yellow with brown dorsal margin of basoflagellomere. Thorax: Scutum blackish, shining, usually with slight dusting anteriorly and laterally. Pili on scutum predominantly yellowish or whitish, rarely partly or totally blackish. Scutellum shining. Pleura mostly bare, blackish, shining or with variable amount of dusting. Katepimeron with widely separated dorsal and ventral pile patches. Metasternum consists of only a narrowly sclerotized anterior and median stripe. Wing: Usually totally microtrichose, at most with small bare areas around base of cell BM. Legs: Coxa blackish. Metacoxa without posterior pile tuft. Femur, tibia and tarsus slender without outstanding pile or bristles. Coloration varies from almost totally yellow to almost totally dark brown. Male abdomen: Nearly parallel sided, two to five times as long as greatest width. Terga 2–4 usually with sub-rectangular yellow maculae, but maculae sometimes darkened and/or reduced to various extent. Yellow maculae shining or with various amount of dusting. Maculae on tergum 2 separated from anterior margin. Maculae on terga 3–4 usually reaching anterior margins. Maculae on terga 2–4 usually reaching lateral margins and separated from posterior margins. Female abdomen: Shape varying from nearly parallel sided to oval; two to four times as long as its greatest width. Terga 2–5 usually with yellow maculae but these maculae sometimes darkened and/or reduced to some extent. Maculae on tergum 2 roundish and separated from the margins. Terga 3–4 with anterior triangular maculae narrowly reaching lateral margins. Tergum 5 with or without anterolateral maculae.