Lonchaea pentecosti, MacGowan, 2021

Macgowan, Iain, 2021, The Lonchaeidae of Vanuatu (Diptera: Schizophora), Zootaxa 4926 (3), pp. 342-362 : 352-354

Lonchaea pentecosti sp. nov. ( Figures 29, 30 )

Description. MALE: Body length 2.6mm.

Head: Eyes bare, frons approximately 0.5x width of eye, sub-shining black, dulled by microsculpture, frontal and interfrontal setulae very short, 0.1x length of orbital seta. Orbital plate shining black, bare apart from the orbital seta. Lunule; ground colour orange-brown, covered in intense silver pollinosity as are the parafacials, face lightly silver dusted. Anterior genal setulae in a single row of five-six along mouth margin, these relatively short, approximately 0.5x depth of antennal postpedicel. Antennae, black, postpedicel length to depth ratio 2.7:1, orange on medial basal third, this colouration extending diffusely along the ventral margin. Arista black with microscopic fringe of setulae which at a maximum is as wide as width of arista at base.

Thorax: scutum and lateral sclerites brightly shining black. Anepisternum, two anterior setae and two posterior setae, otherwise sclerite with only a few scattered setulae 0.3x length of the setae. Katepisternum, one seta situated near dorsal margin. Proepimeron and proepisternum both with one seta. Scutellum, disc almost as shining black as thoracic dorsum, setulose on dorsal surface, margin without additional setulae between the four setae. Calypteres white with a short white fringe. Wings clear, veins light brown, wing length 2.5mm. Legs, black apart from t1 of fore and hind legs which is yellow and has a ventral fringe of stiff yellow setulae.

Male terminalia: In ventral view cerci rather small, not stalked. Surstyli reduced, broadly triangular, with an excavation at medial apex, stiff setulae present on medial margin and on apical half. Pregonites large, equal in size, crescent shaped with a large, triangular median process, a strong medially directed seta present on posterior half. Phallus; a simple J-shape, apical section slightly sinuous, apex simple, basally with a membranous area at anterior angle.

Type material. Holotype ♂: VANUATU: Pentecost Island , 3.iv.1964, R. Straatman ( BPBM).

Paratypes: Epi, Vaemali, 8. viii.1967, J. & M. Sedlacek, 2♂; Vaemali, 19-20. viii.1967, J. & M. Sedlacek, 1♂. Maewo Island, Sounwari, 4-5.ix.1979, G. A. Samuelson, 1♂. Shepherd group, Tongariki Islands, 29.viii.1979, G. M. Nishida, 1♂ (all BPBM).

Etymology. The specific epithet is derived from the island of Pentecost on which the Holotype was captured.

Remarks. This is another member of the L. impressifrons species-group. With its small cerci with basal tubercles, mitten-shaped surstyli and simple J-shaped phallus this species is very similar to Lonchaea iridala also described from Vanuatu. The shape of the pregonites is however different and this distinction has been the basis of describing L. pentecosti as a new species. This corresponds to the identification of many species in the L. impressifrons species-group which relies heavily on the shape of the pregonites.

In L. iridala the pregonites posteriorly are broad and inwardly turned, looking like what McAlpine referred to as “similar to two tiny birds’ heads facing inward”. There is a rather small insignificant medial process with an apical seta and a longer medially directed seta near the posterior apex. In L. pentecosti the pregonites posteriorly form a rather narrow pointed apex which is not inwardly directed, there is a strong seta just anterior to this and a large, bluntly triangular median process with a small seta at its base. The surstyli also seem to have more setulae on the ventral surface than is illustrated for L. iridal a.

Figures

FIGURES 29 & 30. Lonchaea pentecosti sp. nov. 29. Epandrium and associated structures, lateral view. 30. Phallus, lateral view.