Asiobaccha samoaensis Mengual

Mengual, Ximo, 2016, A taxonomic revision of the genus Asiobaccha Violovitsh (Diptera: Syrphidae), Journal of Natural History 50, pp. 2585-2645 : 2622-2623

Asiobaccha samoaensis Mengual sp. nov.

( Figure 9a, b, e )

Baccha praefica of Hull 1929: 194.

Episyrphus (Asiobaccha) praefica of Thompson and Vockeroth 1989: 443 (in part, citation from Samoa).

Description

Male: Head. Face with distinct round facial tubercle, black, black pilose, white-silver pollinose laterally, shiny medially; gena black; lunule black, shiny; frons slightly protruded forward, black, black pilose, dark brown pollinose posteriorly; vertical triangle narrow, isosceles, with the ocelli on the anterior half, black, black pilose; antenna yellow, basoflagellomere brown dorsally, black pilose; arista brown, bare; eye bare, holoptic; occiput black, grey-silver pollinose, pale pilose on ventral 3/4 and dark pilose on dorsal 1/4 ( Figure 9e ).

Thorax. Scutum black with purple iridescence and partly brown pollinose, with short, black pile; mesonotal fringe or collar well-defined on anterior part of scutum, with pale pile; postpronotum black, bare; notopleuron black, pale pilose; scutellum black, brown pollinose on anterior margin, with short, black pile, subscutellar fringe with long, pale pile ( Figure 9a, b ). Pleuron black, white pollinose on dorsal katepisternum and posterior anepisternum; anterior anepisternum yellow pilose on posterodorsal quarter, posterior anepisternum and anepimeron pale pilose; metaepisternum with short, dark pile ventrad to spiracle; metasternum bare; calypter small, reduced, yellow; plumula small, pale; halter dark brown to black; posterior spiracular fringes pale. Wing: alula broad, as broad as or broader than cell BM, microtrichose. Wing membrane infuscated, brown; entirely microtrichose. Legs: dark brown to black.

Abdomen. Parallel sided, slightly petiolate, unmargined; dark with bluish-purple iridescence without pollinosity, or small, black pollinose maculae medially; terga 1 and 2 pale pilose, and terga 4 – 6 black pilose; tergum 3 pale pilose anteriorly and black pilose posteriorly ( Figure 9a, b ); sterna black. Male genitalia dark.

Female. Similar to male except for normal sexual dimorphism and as follows: frons black, shiny, white pollinose only lateroventrally; occiput entirely pale pilose.

Variation. Some specimens may have the face, under the white pollinose laterals, a yellow background. Lighter individuals have basal part of pro- and mesotibiae yellow and postalar callus light brown.

Length (N = 5). Body, 10.0 – 14.5 (12.5) mm; wing, 8.0 – 10.0 (9.4) mm.

Geographical distribution

Species known only from Samoan Islands.

Etymology

The specific epithet is derived from the country ’ s name where the species is found, Samoa, and the Latin suffix - ensis denoting place, locality, country, or belonging to, pertaining to ( Brown 1956, p. 45, 303). Species epithet is to be treated as adjective.

Differential diagnosis

This taxon has the face, the scutellum and the abdomen dark, with purple shine, and it presents a broad alula. It is very similar to A. praefica , both with the metatarsi dark brown or black, but they can be distinguished by the microtrichosity of the basal cells: A. praefica has the cell BM bare basally, and A. samoaensis has the wing entirely microtrichose.

Type locality

American Samoa: Eastern district , Tutuila island, N.P. American Samoa, Mt. ‘ Alava, 300 – 480 m, 14°15 ʹ 53 ʹ ’ S, 170°41 ʹ 17 ʹ ’ W.

Material examined

Type material. Holotype, male, deposited in the Bernice P. Bishop Museum (Honolulu, Hawaii, USA) and labelled: ‘ SAMOA: Tutuila, // Mt. Alava, 300 – // 480 m, 9.III.1971 ’ ‘ N.L.H. Krauss // Collector // BISHOP MUSEUM ’ ‘ HOLOTYPE // Asiobaccha // samoaensis // des. X. Mengual 2014’ [red] (specimen photographed). Paratypes: AMERICAN SAMOA: Tutuila island, N.P. American Samoa, Mt. ‘ Alava , 300 – 480 m, 9 March 1971, N.L.H. Krauss [1♂, BPBM; 1♂, ZFMK, ZFMKDIP 00011919]; Tutuila island, 9 August 1957, W.R. Kellen [1♀, BPBM];..., Pago Pago , 16 April 1924, E.H. Bryan Jr. [1♂, CNC];..., Pago Pago, 21 July 1925, G.P. Wilder [1sp., BPBM];..., Pago Pago , 14 December 1925, P.A. Buxton and G.H. Hopkins [1♀, BPBM];..., Malaota , 10 September 1953, C.P. Hoyt, sweeping ferns [1♂, ZFMK, ZFMKDIP 00011930]; Manu ’ a district, Tau island, Tavalogi Ridge , 165 m, 16 – 19 February 1965, G.A. Samuelson, Malaise trap [2♂ 2♀, BPBM; 1♂ 1♀, ZFMK, ZFMKDIP 00011943, 00011940]. SAMOA: Tuamasaga district, Upolu island, Tuaefu , 16 September 1923, Swezey and Wilder [1♀, BPBM; 1♀, ZFMK, ZFMKDIP 00011938];..., Afiamalu , 19 June 1940, 2100 ft., E.C. Zimmerman, beating [1♀, BPBM];..., Malololelei , 2000 ft., 18 April 1924, P.A. Buxton and G.H. Hopkins [1♂, BPBM];..., 17 June 1924, P.A. Buxton and G.H. Hopkins [1♀, CNC];..., 21 June 1924, J.S. Armstrong [1♀, BMNH];..., 22 June 1924, J.S. Armstrong [1♀, CNC];..., 30 June 1924, J.S. Armstrong [1♀, BPBM]; Palauli district, Savai ’ i island, Sala ’ ilua, 19 May 1924, E.H. Bryan Jr. [1♀, BPBM];..., 21 May 1924, E.H. Bryan Jr. [1♀, BMNH];..., 22 May 1924, E.H. Bryan Jr. [1♂, BMNH];..., Safune , lower forest, 1000 – 2000 ft., 11 May 1924, E.H. Bryan Jr. [1♀, RMNH];..., Asau , 200 m, 3 January 1969, B. Hocking [1♀, ZFMK, ZFMKDIP 00011941].

Figures

Figure 9. Asiobaccha samoaensis Mengual sp. nov. a–b, e, holotype ♂. (a) Dorsal view; (b) lateral view; (e) frontal view. Asiobaccha sauteri (Kertész). c–d, f, lectotype ♂. (c) Dorsal view; (d) lateral view; (f) frontal view. Scale bars: a–d = 2 mm; e, f = 1 mm.