Asiobaccha maculosa Mengual & Thompson

Mengual, Ximo, 2016, A taxonomic revision of the genus Asiobaccha Violovitsh (Diptera: Syrphidae), Journal of Natural History 50, pp. 2585-2645 : 2607-2609

Asiobaccha maculosa Mengual & Thompson sp. nov.

( Figures 6c, d, f , 12e )

Description

Male: Head. Face with facial tubercle, yellow, yellow pilose; gena yellow, slightly white pollinose posteriorly; lunule black; frons yellow with a medial, black macula pointing backwards, yellow pilose, without pollinosity; vertical triangle narrow, black, yellow pilose, white pollinose posteriorly; antenna yellow-brown, yellow pilose; arista brown, bare; eye bare, holoptic; occiput white pollinose, yellow pilose ( Figure 6f ).

Thorax. Scutum brown to black, with short, yellow pile; mesonotal fringe absent; postpronotum yellow, bare, white pollinose; notopleuron yellow, slightly white pollinose, yellow pilose; postalar callus lighter in background colour; scutellum yellow with a posteromedial black macula, yellow pilose, subscutellar fringe absent ( Figure 6c, d ). Pleuron yellow, katatergum and anatergum darker, brownish, yellow pilose; metaepisternum yellow pilose ventrad to spiracle; metasternum bare; calypter yellow; plumula very short, yellow; halter: pedicel yellow, capitulum brown; posterior spiracular fringes yellow. Wing: membrane hyaline; stigma, costal cell and R1 yellow; microtrichose, except cell BM and CuP very basally. Alula present, rectangular, narrower than costal cell, microtrichose. Legs: completely yellow, except metafemur yellow dorsally and dark brown ventrally, with a dark subapical annulus (ring), metatibia yellow with a medial dark annulus.

Abdomen. Petiolate, unmargined. Tergum 1 yellow, yellow pilose; tergum 2 mostly dark, dark brown to black, with a basal yellow fascia (two basal, triangular yellow maculae joined medially) and two lateral yellow maculae, yellow and black pilose; tergum 3 black with two medial, rectangular, large yellow maculae not joined medially reaching lateral margins; tergum 4 black with two submedial, yellow fasciate maculae reaching anterior margin; tergum 5 black with two anteromedial yellow maculae; terga 4 and 5 with posterior margin yellowish ( Figure 6c, d ); sterna 1 – 3 yellowish, sternum 3 with a black fascia, and sterna 4 and 5 dark.

Female. Similar to male except normal sexual dimorphism and as follows: lunule black; frons yellow laterally on basal 1/2 with a medial, black vittae joining the black area on posterior 1/2, shiny on basal 1/2 and yellow pollinose on posterior 1/2 and ocellar triangle. The pollinose area on posterior 1/2 of the frons has a thin, medial shiny vitta ( Figure 12e ). Both female paratypes lack the alula, but this might be due to preservation conditions in author ’ s opinion.

Length (N = 3). Body, 12.0 – 14.0 (13.2) mm; wing, 12.5 – 13.2 (12.7) mm.

Geographical distribution

Sumatra and Malay Peninsula.

Etymology

The specific epithet is derived from the Latin maculosus denoting spotted, dappled ( Brown 1956, p. 742). The name is to be treated as adjective.

Differential diagnosis

This species present a face entirely yellow, not pollinose, frons with a dark macula on lunule, alula very narrow, and the scutellum yellow with a medial, dark macula. This taxon is similar to A. tinctiventris , but it differs in the following characters: alula narrow ( A. tinctiventris has the alula broader than costal cell), frons and face largely shiny, and yellow markings on tergum 3.

Type locality

Indonesia: Sumatra, Bukittinggi , Fort de Kock , 0°18 ’ S, 100°20 ʹ E ( de Jong 2000).

Material examined

Type material. Holotype, male, deposited in the Naturalis Biodiversity Center (Leiden, The Netherlands) and labelled: ‘ Fort de Kock // (Sumatra) 920 M. // 1925 // leg. E. Jacobson ’, ‘ Baccha // Loriae Meij’, ‘ ♂ ’, ‘ HOLOTYPE // Asiobaccha // maculosa // des. X. Mengual 2014’ [red] (specimen photographed). Paratypes: INDONESIA: Sumatra, Bukittinggi, Fort de Kock , 0°18 ’ S, 100°20 ’ E, 1925, E. Jacobson [1♀, RMNH] (specimen photographed); Sumatra, west coast, Tandjunggadang, 1000 m, November 1925, E. Jacobson [1♀, ZFMK, ZFMKDIP 00011937]. MALAYSIA: Pahang, Cameron ’ s Highlands, 3500 ft., 26 May 1931, H.T. Pagden [1♂, USNM, USNMENT00890798].

Remarks

The type material of Asiobaccha maculosa was identified as Baccha loriae Meijere most probably by Pieter H. van Doesburg (Senior). This conclusion by Herman de Jong and Ben Brugge (RMNH) was made after a handwriting comparison with the handwriting on labels of species described by van Doesburg. Originally a coleopterist, van Doesburg started to work on the Syrphidae during the Second World War. He identified remaining unsorted material in the Amsterdam Syrphidae collection, and it must have been in the early 1940s that the identification labels were attached (2014 e-mail from H. de Jong to author).

The type material of A. maculosa does not match the original description of Baccha loriae . Meijere clearly stated that the scutellum was uniform in colour ( de Meijere 1908, p. 319, key couplet 7) and the abdomen had no yellow markings ( de Meijere 1908, p. 319, key couplet 8). The paratypes of A. maculosa , two females and a male, have no alula. After checking the male genitalia and all other external morphological characters, the author could not find any difference except the absence of the alula. Therefore, the author assumes the loss of the alula due to preservation conditions as this has occurred with the lectotype of A. virtuosa .

The Malayan specimen in the USNM was identified as Episyrphus 74–27 Thompson, in litt.

Figures

Figure 6. Asiobaccha loriae (Meijere). a–b, e, ♂. (a) Dorsal view; (b) lateral view; (e) frontal view. Asiobaccha maculosa Mengual & Thompson 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.

Figure 12. Asiobaccha virtuosa (Curran). a–b, d, lectotype ♂. (a) Dorsal view; (b) lateral view; (d) frontal view. Asiobaccha maculosa Mengual & Thompson sp. nov., paratype ♀. (c) Dorsal view. Asiobaccha nubilipennis (Austen), ♀. (e) Frontal view. Asiobaccha tinctiventris (Meijere), ♂. (f) Frontal view. Scale bars: a–c = 2 mm; d–f = 1 mm.