Citrogramma triton, Mengual, 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 : 166

CITROGRAMMA TRITON MENGUAL SP. NOV.

Description

Male: See description of C. schlingeri and C. distinctum above. Morphologically, C. triton , C. schlingeri , and C. distinctum are identical. The only remarkable difference is the male genitalia (see Figs 141– 143 ).

Female: See description of females given above under the C. schlingeri species group.

Length (N = 2): Body, 9.6–10.2 (9.9) mm; wing, 9.2–9.8 (9.5) mm.

Geographical distribution: New Guinea.

Etymology: The specific epithet is derived from the Greek tritos meaning third ( Brown, 1956: 798), and it refers to the fact that it is the third species found with the same adult morphology and different male genitalia. Species epithet to be treated as adjective.

Differential diagnosis: See comments on C. schlingeri and C. distinctum above. Species with entirely yellow face, gena yellow, broad frontal triangle (eye angle more than 90°) with a narrow black fascia on eye margin, costal cell darker than the rest of the wing membrane (except stigma), brown macula on scutellum and legs almost entirely black. As mentioned, this species is difficult to distinguish from others in its group, like C. schlingeri or C. distinctum ; only male genitalia are different. Citrogramma pintada and C. pinyton are very similar and they probably belong to the same species group, but these have anepisternum yellow.

Remarks: Thompson discovered two new species, C. schlingeri and C. distinctum , while studying Citrogramma material at AMNH. After the study of BPBM material, a third species with the same adult morphology was found, C. triton . The three species are known from New Guinea and only the male genitalia are clearly different for each of them. Females of this species group are described together. Probably they are all a sympatric cryptic species complex, occurring in the same geographical area.

Holotype male deposited in the Bernice P. Bishop Museum (Honolulu, Hawaii, USA) and labelled: ‘NEW GUINEA: NE/Mt Shungol,/ 270 0 m, 31.V.1967 ’ ‘J.L. Gressit/& P. Colman/BISHOP MUSEUM’ ‘ HOLOTYPE / Citrogramma / triton /det. X. Mengual 20 10 ’ [red, second and third lines handwritten].

Type locality: Papua New Guinea: Morobe Province, Mount Shungol (also known as Mount Chungol ), 2700 m, 6°51′S, 146°42′E .

Material examined: Type material. Holotype, as above. Paratype. PAPUA NEW GUINEA: Enga Province, Yaibos , 2030–2180 m, 11.vi.1963, J. Sedlacek [1♂, BPBM] .

Figures

Figures 140–144. Male genitalia. 140, Citrogramma bicornutum (from Vockeroth, 1969): a, left lateral view; b, superior lobe, lateral, outline only; c, sternum 9, superior lobes and aedeagal base, ventral view; d, right surstylus, lateral view. 141, Citrogramma schlingeri, left lateral view. 142, Citrogramma distinctum, left lateral view. 143, Citrogramma triton, left lateral view. 144, Citrogramma frederici, left lateral view.