Lonchaea vanua, Macgowan, Iain, 2014

Macgowan, Iain, 2014, The Lonchaeidae of Fiji (Diptera: Schizophora), Zootaxa 3814 (4), pp. 537-552 : 540-541

Lonchaea vanua sp. nov.

Description. Male: Head. Eyes bare. Frons subshining black, dulled by microsculpture. Lunule covered in silver pollinosity, face orange brown above mouth, orbital plates shining, bare apart from orbital seta. Antennae entirely black, inner ventral surface of 1st flagellomere narrowly orange brown, 1st flagellomere 2.75x as long as deep, just reaching to mouth margin, arista with short pubescence, at maximum 40% depth of 1st flagellomere. Anterior genal setulae in a single row, basal setulae strong and seta-like.

Thorax: Thoracic dorsum and scutellum glittering black with slight bluish reflections. Thoracic sclerites brightly polished. Anepisternum with two strong anterodorsal setae and two posterior, the remainder of the sclerite covered in long but rather sparse black setulae. Katepisternum with one strong dorsocentral seta, anterior to this approximately 6 short setulae, one posteriorly. Calypteres white with a white fringe. Wing length 2.8mm. Abdomen shining brownish, slight bluish reflection on lateral margins.

Male terminalia: ( Figs. 21–23 ). In lateral view epandrium 1.5x higher than wide, bearing setulae posteroventrally; cerci small and square-shaped, bearing strong setulae along posterior margin, these slightly weaker ventrally. Surstyli projecting ventrally beyond shell of epandrium as a broad lobe, internal surface with numerous setulae along outer margin, inner surface bare apart from a single row of 8 long setulae parallel to ventral margin, these becoming longer posteriorly with the most posterior extending out beyond margin of epandrium. Phallus slender and rather rectangular, with no setulae, obviously two segmented.

Type material: Holotype ♂. FIJI ; Vanua Levu, Macuata prov., 0.4km S. Rokosalese village, 16º532’S 179 º019’E, 118m, 23.iv–8.v.2004, leg. Schlinger & Tokota’a.

Differential diagnosis: Lonchaea vanua is the smallest of the Lonchaea species known from Fiji , the hairing on the arista is also the shortest of the four species. The male genitalia are distinct due to the row of long setulae present on the inner surface of the surstyli.

Remarks. All four Lonchaea species recorded from Fiji , L. fiji , L. melanesia , L. linefacies and L. vanua , are externally very similar and form a closely related and distinctive group within the genus. All have plumose arista, a strong seta-like setula on the genae and anepimeron with two anterodorsal and posterior setae. The male genitalia indicate that these are definitely Lonchaea species, the inner surface of the surstyli bearing setulae, there are no prensisetae on a basal plate as would be found in the genus Silba .

Figures

FIGURES 21 – 23. Lonchaea vanua sp. nov. 21. Epandrium and associated structures lateral view. 22. Internal view of surstylus. 23. Phallus lateral view.