Citrogramma australe, 2012

Mengual, Ximo, 2012, The flower fly genus Citrogramma Vockeroth (Diptera: Syrphidae): illustrated revision with descriptions of new species, Zoological Journal of the Linnean Society 164 (1), pp. 99-172 : 129-130

CITROGRAMMA AUSTRALE THOMPSON SP. NOV.

Description

Male: Head: Face with small facial tubercle, yellow with medial thin dark vitta, from oral apex to antennal base, narrower than yellow lateral areas of face, yellow pilose; gena yellow, yellow pilose, white pollinose posteriorly; lunule yellow; holoptic; frontal triangle yellow, black pilose; vertical triangle black, a bit shorter than eye contiguity, black pilose; ocelli reddish; antenna dark yellowish, black pilose on scape and pedicel; basoflagellomere orangish, dark dorsally; arista dark; occiput black, silver pollinose, golden pollinose dorsally, pale pilose on ventral two thirds, dark pilose on dorsal third.

Thorax: Scutum black with dorsomedial grey pollinose area with metallic iridescence forming two anteroposterior vittae (see variation), with a lateral broad yellow vitta, black pilose dorsally, yellow pilose laterally on yellow vitta, densely yellowish pilose on lateral notopleuron and supra-alar area; postpronotum yellow, notopleuron yellow continuing until scutellum, with postalar callus entirely yellow, black and yellow pilose; scutellum yellow laterally and anteriorly with dorsomedial semicircular defined brown macula not reaching anterior margin, black pilose, with a sparse subscutellar fringe with black hairs. Pleuron mostly yellow, except posterior anepisternum black on anterior half and dorsally, katepisternum black with dorsal yellow macula, meron black, anterior anepimeron black, katatergum black posteriorly, entirely yellow pilose; metasternum pilose; ventral calypter yellow with yellow hairs on margin, dorsal calypter yellow, darkened anterodistally; plumula yellow; halter pedicel yellow with capitulum brown; spiracular fringes yellow.

Wing: Wing membrane brown, entirely microtrichose. Alula microtrichose, broad, broader than costal cell and slightly broader than cell BM.

Legs: Pro- and metacoxa and trochanter yellow, mesocoxa and mesotrochanter brownish yellow; profemur and tibia yellow; mesofemur yellow, brownish on distal one fifth or less; pro- and mesobasotarsomere yellow brown basally, dark distally, rest of tarsi black; metafemur, metatibia, and metatarsi black, metafemur brownish only very basally with short, strong, rather setulose, anteroventral and posteroventral hairs near apex. Legs black pilose with yellow hairs on coxae.

Abdomen: Figure 22 . Parallel-sided, slightly margined on terga 4 and 5. Dorsum mainly black, black pilose dorsally and laterally except tergum 1 yellow pilose laterally and tergum 2 yellow pilose laterally on anterobasal half; tergum 1 black, yellow laterally; tergum 2 black with two mesolateral triangular yellow maculae, yellow lateral margin on anterior half; terga 3 and 4 black with a medial broad (about half of the tergum length) yellow fascia with anterior margin parallel to tergal margin and posterior margin concave; tergum 5 similar to 3 and 4, black with medial yellow fascia narrowed dorsomedially; terga 2, 3, 4, and 5 with a posterior narrow pollinose fascia on posterior margin; sterna yellow, sterna 1 and 2 yellow pilose, everywhere else black pilose; genital segments brownish; male genitalia large reaching posterior margin of sternum 4, sternum 5 modified to accommodate it, brown, as in Figures 138 and 139 .

Female: Unknown (but see comments under C. notiale ).

Variation: The two studied males differ in the grey pollinose area on dorsal scutum. The scutum of the paratype has no clear evidence of the metallic iridescence and looks like a black scutum with grey or black pollinosity, probably because it was wetted. The holotype has this metallic iridescence but because of the pin, it is not clear if the grey central pollinose area is undivided like C. robertsi , or divided into two vittae, like C. notiale .

Length (N = 2): Body, 8.0–8.3 (8.2) mm; wing, 7.0–7.5 (7.3) mm.

Geographical distribution: Australia.

Etymology: The specific epithet is derived from the Latin australis meaning austral, southern ( Brown, 1956: 112). It refers to the type locality of the species, very south in the genus distribution and from Australia. Species epithet to be treated as an adjective.

Differential diagnosis: Species difficult to distinguish from C. notiale and found in the same region (Sydney and Brisbane, Australia). Males of these two species can be distinguished only using genitalia. Very different species from the rest with a medial black facial vitta, wing completely microtrichose, and scutellum with a dark medial macula not reaching anterior margin. The abdomen is almost parallel-sided with tergum 2 with two subtriangular yellow maculae, and a broad yellow fascia on terga 3, 4, and 5 ( Fig. 22 ).

Remarks: The male genitalia of the paratype (Mt Glorious, 8.xi.1969) are broken in multiple parts, but the singular lingula that this species has can be seen in one of these fragments. The other paratype also has the lingula broken. Only four Citrogramma species have lingula present in the male genitalia: C. australe , C. notiale , C. asombrosum , and C. quadricornutum .

Holotype male deposited in the Australian National Insect Collection, CSIRO (Canberra, Australia) and labelled: ‘?BRISBANE,/Q’land/C. F. Ashby’ ‘ HOLOTYPE / Citrogramma / australe /det. X. Mengual 20 09 ’ [red, second and third lines handwritten].

Type locality: Australia: Queensland, Brisbane , 27°28′S, 153°01′E .

Material examined: Type material. Holotype, as above. Paratypes. AUSTRALIA: Brisbane, Queensland, C.F. Ashby [1♂, ANIC];..., Mt Glorious , 8.xi.1969, J.K. Guyomar [1♂, ANIC] .

Figures

Figures 15–26. Dorsal view of abdomen. 15–16, Citrogramma bicornutum: 15, female; 16, male. 17, Citrogramma asombrosum, male. 18–19, Citrogramma quadratum: 18, male; 19, female. 20–21, Citrogramma arisanicum: 20, male; 21, female. 22, Citrogramma australe, male. 23–24, Citrogramma notiale: 22, female; 24, male. 25–26, Citrogramma robertsi: 25, female; 26, male.

Figures 131–139. 131–134, microtrichia pattern of wing. 131, Citrogramma pendleburyi. 132, Citrogramma marissa. 133, Citrogramma clarum. 134, Citrogramma sp. B. 135–137, Citrogramma asombrosum, male genitalia: 135, left lateral view; 136, tergum 9 and surstyli, dorsal view; 137, terga 7, 8, and 9, and surstyli, lateroventral view (as in pinned specimen). 138–139, Citrogramma australe: 138, left lateral view; 139, tergum 9 and surstyli, dorsal view.