Ubristes flavitibia Walker 1852
Creators: name: Reemer, Menno
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Syrphidae
Ubristes
Ubristes flavitibia

description: Ubristes flavitibia Walker, 1852
Figs 252–255, 265.
Ubristes flavitibia Walker, 1852: 217.
Microdon procedens Curran, 1941: 251. Syn. nov. Microdon procteri Curran, 1941: 251. Syn. nov.
Studied type specimens. HOLOTYPE Ubristes flavitibia. BRAZIL. Male. Label 1: " Holotype "; label 2: " Type "; label 3: " Ubristes flavitibia "; label 4: " Ubristes flavitibia Wlk. " Coll. BMNH.
HOLOTYPE Microdon procedens.— Male. Label 1 (red): " Microdon procedens Curran Holotype "; label 2: " Brasilien, Nova Teutonia, 27°11’ B, 52°23’L. Fritz Plaumann. 27.10.1939 ". Coll. AMNH.
PARATYPE Microdon procedens. BRAZIL. Male. Label 1: " Brasilien, Nova Teutonia, 27°11'B, 52°23'L. 24.10.1939. Fritz Plaumann"; label 2: " Paratype, male, Microdon procedens Curran ". Coll. USNM.
HOLOTYPE Microdon procteri. BRAZIL. Male. Label 1 (red): " Microdon procteri Curran Holotype "; label 2: " Brasilien, Nova Teutonia, 27°11’ B, 52°23’L. Fritz Plaumann. 28.9.1939 ". Coll. AMNH.
Additionally studied specimens. BRAZIL: 1 female, Tijuca forest near Rio, 7-30.ix.1993, leg. T. Pape, coll. ZMUC.
Redescription (based on holotype U. flavitibia)
Adult male. Body size: 11 mm.
Head. Face occupying 1/3 of head width in frontal view; black, with two yellow submedian vittae on upper half, reaching antennal fossa, and a small yellow mark along eye margin on ventral half; with long white pilosity and a dense patch of black pile anterior to oral margin. Gena black. Oral cavity with lateral margins produced. Frons and vertex black and black pilose, with some white pile along eye margins and along transition between frons and vertex. Occiput black; grey pollinose; black pilose dorsally, white pilose ventrally. Eye very sparsely and short pilose, with pili about as long as ommati diameter, appearing bare under low magnification. Antennal fossa about as wide as high. Antenna brown, scape a little paler; antennal ratio 8:1:10; basoflagellomere parallel-sided with narrowly rounded apex, with sensory pit located at 3/4 from base, within a groove that ranges from the base of the arista to close to the apex. Arista slender, about 2/3 of length of basoflagellomere.
Thorax. Black, a little brownish on postpronotum, postalar callus, scutellum and pleurae. Scutum densely black pilose, except for some white pile along transverse suture and a small patch of white pile anterior to the scutellum. Postpronotum, postalar callus and scutellum black pilose. Scutellum without calcars. Anterior and posterior part of anepisternum divided by a weak sulcus; anterior part black pilose, posterior part black pilose along posterior margin. Anepimeron black pilose on dorsal 2/3. Katatergum and anatergum long and short microtrichose, respectively. Other pleurae bare. Calypter greyish, halter yellow with grey knob.
Wing: hyaline, brownly infuscated along anterior margin. Microtrichose except bare on posterobasal 1/2 of cell br and almost entirely on alula (only a narrow basal strip with microtrichia).
Legs: Front- and mid-femora brown, black pilose; hind-femur brown with apical 1/4 yellow, with long black pile. Front-tibia brown, black pilose; mid-tibia yellowish brown, with long black pile; hind-tibia yellow, with very long (some longer than maximal width of tibia) yellow pile on basal 3/4, long black pile on apical 1/4. Tarsi yellow, with basal tarsomeres a bit darker, black pilose dorsally, mid- and hind-tarsi ventrally with dense, short, yellow pile. Coxae and trochanters brownish black, with white pile.
Abdomen. Black. Tergite 1 with anterior half concave, laterally with white pile. Tergite 2 about as wide as thorax, with two lateral´bulges´halfway, which mark the maximum width of the abdomen; with long white pile anterolaterally, rather long black pile on the lateral 'bulges' and short, appressed pale pile on posterior half of tergite. Tergites 3 and 4 ith short black pile over entire surface and long black pile along posterior margin. Sternites 1 and 2 with long white pile; sternites 3 and 4 with mixed long black and white pile. Hypopygium yellowish. Genitalia as in fig. 265.
Female. As male, except for usual sexual differences.
Diagnosis. Within Ubristes s.s. this is the only known entirely black coloured species.
Notes. The types of Microdon procedens and M. procteri (8-9 mm) are smaller than the type of Ubristes flavitibia (11 mm). Besides that, the types of M. procedens differ from U. flavitibia only in the colour of the pile on the hind tibia: mostly brown (not black, as stated by Curran 1941) in M. procedens, yellow in U. flavitibia. However, it appears that the pilosity on the tibia of the type specimens of M. procedens has lost its natural colour and turned brown. No differences could be found in external morphology or genitalia. The type of M. procteri is even more similar to that of U. flavitibia. Therefore, both M. procedens and M. procteri are here considered as junior synonyms of U. flavitibia.
Distribution. Known from southern parts of Brazil.
description: Published as part of Reemer, Menno, 2013, Taxonomic exploration of Neotropical Microdontinae (Diptera: Syrphidae) mimicking stingless bees, pp. 1-88 in Zootaxa 3697 (1) on pages 79-80, DOI: 10.11646/zootaxa.3697.1.1, http://zenodo.org/record/284383