Asiobaccha bimaculata ( Keiser, 1952 ) Mengual, Ximo, 2016

Mengual, Ximo, 2016, A taxonomic revision of the genus Asiobaccha Violovitsh (Diptera: Syrphidae), Journal of Natural History 50, pp. 2585-2645 : 2600-2602

Asiobaccha bimaculata ( Keiser, 1952) comb. nov.

( Figure 5a, b, e )

Baccha bimaculata Keiser, 1952: 161 . Holotype: ♀, NMB. Type locality: Indonesia: Langgai . Baccha (Allobaccha) bimaculata of Knutson et al. 1975: 321.

Differential diagnosis

Dark species with yellow face and scutellum ( Figure 5a, e ), with broad alula, and infuscated wing, which is bare basally (including basal part of cell R) ( Figure 5b ). It has a well-defined mesonotal collar, and the metatarsus is bicolourous ( Figure 5a ). The most similar species is A. nubilipennis , but A. bimaculata differs from it by having tergum 3 black with two medial subtriangular yellow maculae, pointing anteriorly and not reaching lateral margins ( A. nubilipennis has a complete yellow fascia on tergum 3) and the colour of the pleural pollinosity (golden in bimaculata and white-yellow in nubilipennis ). Another characteristic to separate both species is the colouration of the metafemur; A. bimaculata has the metafemur dark brown with a yellow apex, while A. nubilipennis has a yellow metafemur with a medial dark annulus.

Variation. A paler specimen has metafemur yellow very basally and apically.

Length (N = 4). Body, 12.7 – 14.0 (13.2) mm; wing, 10.5 – 12.7 (11.3) mm.

Geographical distribution

Species known from Sumba Island.

Type locality

Indonesia: East Nusa Tenggara Province, Pulau Sumba, Sumba Tengah ( Central Sumba Regency , Langgai , 10°03’S, 120°28ʹ E.

Material examined

Type material. Holotype, female, deposited in the Naturhistorisches Museum (Basel, Austria) and labelled: ‘ TYPUS ’ [red] ‘C.- SUMBA // Langgai // 16.7.1949 // Expedition // Bühler-Sutter ’, ‘ HOLOTYPE // Asiobaccha // bimaculata // (Keiser) // det. X. Mengual 20 14’ [red] (specimen photographed). Paratypes: ‘ PARA- // TYPUS ’, ‘C.- SUMBA // Langgaliru // 5.10.1949 // Expedition // Bühler-Sutter ’, ‘ PARATYPE // Asiobaccha // bimaculata // det. X. Mengual 20 14’ [yellow] [1♀, NMB]; ‘ PARA- // TYPUS ’, ‘O.- SUMBA // Lalukku // 7.7.1949 // Expedition // Bühler-Sutter ’, ‘ PARATYPE // Asiobaccha // bimaculata // det. X. Mengual 20 14’ [yellow] [1♀, NMB].

Nontype material. INDONESIA: East Nusa Tenggara Prov., Sumba, near Lewapaku, km 57 on Waingapu to Waikobubak road, 9 – 12 December 1985, J.D. Weintraub [1♀, USNM, USNMENT 00890789 ] .

Figures

Figure 5. Asiobaccha bimaculata (Keiser). a–b, e, holotype ♀. (a) Dorsal view; (b) lateral view; (e) frontal view. Asiobaccha doesburgi Mengual sp. nov. c–d, f, holotype ♂. (c) Dorsal view; (d) lateral view; (f) frontal view. Scale bars: a–d = 2 mm; e, f = 1 mm.