Citrogramma solomonense, WYATT, 1991

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 : 164-165

CITROGRAMMA SOLOMONENSE WYATT, 1991

Citrogramma solomonensis Wyatt, 1991: 162 . Holotype: ♂, BMNH, by original designation. Type locality: Solomon Islands: Jonapau. Wyatt, 1991: 157, 162, figs 4, 8.

Description

Male: See original description in Wyatt (1991: 162).

Female: Head. Face with facial tubercle, gradually sloping dorsally, more abrupt ventrally, yellow with medial black vitta, from oral apex to antennal basis, narrower than yellow lateral areas of face, yellow pilose, dark pilose laterodorsally, white pollinose laterally; gena yellow with a dark macula medially on genal groove, ventrad to eye, mainly yellow pilose with dark hairs on the dark macula, white pollinose posteriorly; lunule dark; frons yellow with medial triangular dark brown macula towards ocellar triangle not reaching posterior black area, black lateral margin on posterior half forming a yellow inverted V-shaped vitta, black pilose; vertical triangle black, black pilose; ocelli reddish; antenna brownish, black pilose on scape and pedicel; basoflagellomere dark dorsally; arista black; occiput black, mainly silver pollinose, golden pollinose dorsally, yellow pilose on ventral two thirds, black pilose on dorsal third.

Thorax: Scutum black with dorsomedial area almost uniformly grey pollinose with some metallic iridescence, with lateral yellow vitta and sublateral matte black vitta, black pilose dorsally, postpronotum, notopleuron and supra-alar area yellow pilose, postalar callus black pilose, densely yellow pilose on lateral notopleuron and supra-alar area; postpronotum yellow; notopleuron yellow continuing until scutellum, with postalar callus entirely yellow; scutellum yellow with dorsomedial broad defined triangular black macula reaching posterior margin, black pilose, with complete subscutellar fringe with black hairs. Pleuron mostly yellow, except posterior anepisternum black on anterior half, katepisternum black with a dorsal yellow macula, meron black, katatergum blackish posteriorly, entirely yellow pilose; metasternum pilose; calypter yellow, blackened basally, with yellow and black hairs on margin; plumula yellow; halter yellow; spiracular fringes yellow.

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

Legs: Pro- and metacoxa and trochanter brownish, metacoxa and trochanter black; pro- and mesofemur and tibia yellow; pro- and mesotarsus dark; metaleg black, metafemur brownish basally.

Abdomen: Figure 40 . Parallel-sided, slightly oval; terga 2, 3, 4, and 5 clearly margined. 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 curved yellow maculae, laterally extending forward to anterolateral tergum margin, yellow lateral margin on anterior two fifths; terga 3 and 4 black with sinuate yellow fascia on anterior half of the tergum, about third of tergum length, pointed forward medially and on lateral margin, not narrowed laterally; tergum 5 black with a yellow fascia, broader laterally.

Variation: There are significant differences between males and females. In males, the frontal triangle is yellow with a medial triangular black macula pointed dorsally; the dorsal part of the occiput is yellow pilose; anepisternum black ( Fig. 31 ); and coxa and trochanter are black. Amongst the males, the extension of the black macula on genal groove varies ( Fig. 38 ). In male specimens in perfect condition, the pollinose area of scutum has two black vittae. Female specimen has the scutum broken and pollinose area is not clear.

Length (N = 5): Body, 11.0–11.6 (11.2) mm; wing, 9.0– 9.9 (9.4) mm.

Geographical distribution: Solomon Islands, Papua New Guinea (Boungainville and New Britain islands).

Differential diagnosis: Species with a black facial vitta, wing entirely microtrichose, scutum with broad lateral yellow vitta, scutellum yellow with a black macula ( Figs 39, 40 ), katepisternum with a dorsal large yellow macula, and pro- and mesofemur yellow. Citrogramma solomonense is similar to C. hervebazini but C. solomonense has yellow gena with a black macula on genal groove ( Fig. 38 ), halter entirely yellowish, notopleuron and supra-alar area yellow pilose ( Fig. 31 ), and small male genitalia.

Holotype male deposited in The Natural History Museum, formerly British Museum (Natural History) (London, UK) and labelled: ‘SOLOMON IS./ Guadalcanal/ Jonapau / 29:vi: 195 6 /E.S. Brown/ 5380 ’ [sixth line in vertical] ‘HOLO–/TYPE’ [red, round] ‘ HOLOTYPE ♂ of / Citrogramma / solomonensis n.sp. / det. N.P. Wyatt 198 9 ’.

Type locality: Solomon Islands: Guadalcanal Province, Mount Chaunapaho (= Jonapau), 9°37′S, 160°07′E .

Material examined: Type material. Holotype, as above. Paratypes. SOLOMON ISLANDS: Guadalcanal Province, Jonapau , 29.vi.1956, E.S. Brown [2♂, BMNH]

Nontype material. SOLOMON ISLANDS: Guadalcanal, Suta (Suta-Gold Ridge), Mt Jonapau, 1000 m, 29.vi.1956, J.L. Gressitt [3♂, BPBM]; PAPUA NEW GUINEA: Bougainville Island (= North Solomons ), Kokure , 690 m. , 11.vi.1956, E.J. Ford, Jr. [2♂, BPBM];..., 8.vi.1956,... [1♂, BPBM];..., 12.vi.1956,... [1♂, BPBM];..., 14.vi.1956,... [1♂, BPBM];..., 15.vi.1956,... [1♂, BPBM];..., 17.vi.1956,... [1♂, BPBM];..., 21.vi.1956,... [1♂, BPBM]; Bougainville Island, Guaba, 720 m, 19.vi.1956. E.J. Ford, Jr. [1♂, BPBM]; West New Britain Province, Gisiluva, Nakanai Mts. , 1050 m, 25.vii.1956, E.J. Ford, Jr. [1♀, BPBM] .

Figures

Figures 39–50. 39–40, Citrogramma solomonense: 39, dorsal view of male abdomen; 40, dorsal view of female abdomen. 41, Citrogramma hervebazini, dorsal view of female abdomen. 42–44, Citrogramma quadricornutum: 42, dorsal view of male abdomen; 43, dorsal view of female abdomen; 44, dorsal view of male scutum and scutellum. 45, Citrogramma fumipenne, dorsal view of male abdomen. 46–49. Citrogramma luteifrons: 46, dorsal view of female head; 47, dorsal view of male abdomen; 48, lateral view of male pleuron and head; 49, dorsal view of female abdomen. 50, Citrogramma schlingeri, dorsal view of male head.

Figures 27–38. 27–28, Citrogramma robertsi: 27, dorsal view of male head; 28, dorsal view of female head. 29, Citrogramma hervebazini, dorsal view of male abdomen. 30, Citrogramma vockerothi, dorsal view of male abdomen. 31, Citrogramma solomonense, lateral view of male pleuron. 32, C. vockerothi, lateral view of male pleuron and head. 33–37, Citrogramma circumdatum: 33, dorsal view of male abdomen; 34, dorsal view of female abdomen; 35, lateral view of male pleuron; 36, dorsolateral view of female scutum and pleuron; 37, dorsal view of female head; 38, C. solomonense, lateral view of male head.