Eosphaerophoria vietnamensis Mengual, 2010:73

Species with 2nd abdominal tergum black dorsally and 2 lateral yellow maculae on 5th tergum, with notopleuron produced posterolaterally. Similar to E. marginata, but Eosphaerophoria marginata has bigger yellow maculae on the 5th abdominal tergum and narrower yellow fasciae on the 3rd and 4th terga. The male genitalia is very similar in these two species, but E. marginata has the right superior lobe broader and without a posterior tooth being very different from left superior lobe. Eosphaerophoria vietnamensis also has asymmetrical superior lobes, but the right superior lobe has a posterior tip or tooth and is thinner in the posterior section than that in E. marginata.

Eosphaeroporia vietnamensis Mengual, 2010.

Mengual, X. & Ghorpade, K. (2010) The flower fly genus Eosphaerophoria Frey (Diptera, Syrphidae). ZooKeys 33, 39-80.

Vockeroth (1969: 135) cited these specimens as E. dentiscutellata. Mengual et al. (2009: 8) mentioned them as new species.

Male. Head. Face straight, with distinct round tubercle, yellow, yellow pilose; gena yellow, yellow pilose; lunula yellow; frons completely black on dorsal 2/5 (length between anterior ocellus and lunula), yellow on ventral 3/5 with medial black triangular emargination abruptly narrowed reaching the 1/2 of yellow area, not reaching lunula, with small tubercle dorsally to frontal sulcus elevating vertex, yellow pilose in yellow areas and dark pilose in black areas; dichoptic; vertex and vertical triangle black; ocelli brownish; antenna orange, basoflagellomere dark brown on dorsal 1/2, oval; arista brown; occiput mainly black, yellow ventrally, silvery pollinose and yellow pilose ventrally, black pilose and golden pollinose dorsally.

Thorax. Scutum black, shiny medially, black pollinose laterally, golden brown pilose with yellow pile on notopleuron, yellow laterally with lateral yellow stripe from postpronotum to scutellum, narrower after transverse suture with ventral black area; postpronotum yellow; notopleuron yellow with small posterolateral protuberance, not as evident as in E. dentiscutellata; scutellum triangular, pointed posteriorly with small blunt tubercle on medial posterior margin, yellow with dorsomedial triangular black area continuing from posterior mesonotum, brownish pilose; propleuron, anepisternum and anepimeron entirely yellow; katepisternum black with a dorsal yellow macula; meron black; katepimeron yellow; katatergum mainly yellow, black posteriorly; calypter dark brown; halter yellowish. Wing. Wing bare basomedially. Legs. Pro- and mesoleg entirely yellow, except distal part of mesofemur and basal part of mesotibia dark, yellow pilose except tarsi with short black setulae ventrolaterally; metacoxa and trochanter yellow; metafemur yellow basally, black distally on less than 1/2, with 2 ventral rows (one posteroventral and another anteroventral, less evident) of short strong black spine-like setulae on the apical 1/2; metatibia black, black pilose; metatarsus black, black pilose dorsolaterally and golden pilose ventrolaterally.

Abdomen. Dorsum mainly black, dorsally black pilose, 1st tergum and anterior part of 2nd tergum laterally yellow pilose; 1st tergum black with very narrow yellow fascia on anterior margin following sclerite shape, and lateral yellow margin; 2nd tergum black, yellow on anterior 1/3 of lateral margin continuing the yellow lateral margin of 1st tergum; 3rd tergum black with basal narrow yellow fascia, about 1/5 of tergum length, becoming broader medially and ending in a posteriorly pointed emargination at medial point reaching the 1/3 of tergum length, yellow on anterior 1/2 of lateral margin; 4th tergum similar to 3rd, black with basal broader yellow fascia, about 1/3 of tergum length, produced posteriorly in a medial triangular emargination reaching half length of tergum, yellow on anterior 1/2 of lateral margin; 5th tergum black with 2 anterolateral small yellow maculae, difficult to see on dorsal view; sterna brownish yellow, yellow pilose; 4th sternum with posterior margin produced medially into 2 projections with black setulae; male genitalia as figured.

Female. Similar to male except for normal sexual dimorphism and: face yellow with medial diffuse black vitta narrowing to tubercle tip not reaching oral apex; lunula black; frons completely black on dorsal 1/4 (length between anterior ocellus and lunula), yellow on basolateral 3/4 with medial broad well-defined black vitta slightly narrowing ventrally (about 3/5 of frons width) and reaching lunula; scutellum without blunt knob on posterior margin, with dorsomedial black area smaller. Metafemur apparently without ventral black setulae except one seen on left metaleg. 1st tergum black with anterior and lateral yellow margin, medially reaching the anterior margin of the 2nd tergum dividing black area in 2 triangular maculae; 3rd abdominal tergum black with basomedial very narrow black fascia and with basal yellow fascia, about 1/5 of tergum length, produced posteriorly in a medial triangular emargination reaching half length of tergum, yellow on anterior 1/2 of lateral margin; 4th abdominal tergum black with basomedial very narrow black fascia and with a basal broader yellow fascia, about 1/3 of tergum length, not produced posteriorly, yellow on anterior 1/2 of lateral margin; 5th abdominal tergum black with 2 basolateral yellow maculae, leaving the medial 1/3 black, yellow on lateral 1/2; 6th abdominal tergum black with 2 anterolateral yellow maculae; 6th, 7th and 8th sterna with long black pile on posterior margin medially.

Variation. A couple of male specimens have the frons with a medial black very narrow vitta continuing from the abruptly narrowed emargination to lunula. In these cases, this thin vitta reaches lunula, and specimens have the lunula a bit darker medially. Another male individual has no posterior small blunt knob on scutellum, and its posterior margin is more rounded. Some specimens present the metafemur with short black setulae on the apical 2/3, but others on less than apical 1/2. We think that these setulae can be lost in part in dried pinned specimens.

Eosphaerophoria vietnamensis and E. symmetrica were both collected in Vietnam, but they can be easily differentiated by the abdominal pattern and male genitalia.

Length (5): body, 4.9–6.1 (5.6) mm; wing, 4.0–4.7 (4.3) mm.

Type material was collected in Vietnam (Lam Dong, Dà Lat. 11°56'43.51"N 108°26'31.59"E). There is also a male from Pahang Province (Malay Peninsula; Malaysia).

The Malaysian specimen, collected in the same area of type locality for E. brunettii, is tentatively included in this species based on colour pattern of 1st and 2nd abdominal terga, the lateral yellow stripe of the scutellum and the metaleg. But because the posterior part of abdomen and male genitalia are lost, it can not be identified with certainty.