Lonchaea baechlii MacGowan

Iain Macgowan & Gerhard Bächli, 2016, New species of Lonchaeidae (Diptera) from Switzerland and Serbia with arevised checklist of the Swiss fauna, Mitteilungen Der Schweizerischen Entomologischen Gesellschaft 89, pp. 169-176 : 169-171

Lonchaea baechlii MacGowan sp. nov.

( Figs 1–4 )

Description.Male. Head: Eyes bare. Frons at narrowest point just above the lunule rather narrow, ratio at this point to width of an eye 1:2.8, velvet black, frontal and interfrontal setulae short and scattered, length no more than approximately 0.2x that

169 of orbital seta, longer on anterior margin above lunule. Orbital plate shining blueblack, bare apart from orbital seta. Lunule very dark brown, bearing setulae, face sub-shining black. Anterior genal setae the strongest setulae on the genae, forming asingle regularly spaced row of 5–6 along mouth edge. Antennal flagellomere with length to depth ratio 1.7:1, black apart from an obscure orange area at medial base, arista black, microscopically pubescent.

Thorax: Scutum shining blue-black, with adense covering of black setulae which are approximately 30 %length of orbital seta. Anepisterum with 3anterior setae (perhaps afourth weak one at the ventral end of the row) and four posterior, other setulae on the sclerite long, almost the length of the anterior row of setae. Proepisternum with 1seta, this longer and stronger than the single seta on the proepimeron. Katepisternum with two long setae on each side, anterior slightly weaker than posterior, afew short setulae lying anterior to these, and on left side with one small setula posterior to the seta. Scutellum pollinose on disc, on margin with 3setulae on each side between lateral setae, none between apical setae. Calypteres pale, fringe short and light gold in colour. Wing clear slightly yellow tinged anteriorly. Wing length 3.6 mm. Legs, including all tarsomeres, entirely black.

Male terminalia: In lateral view epandrium slightly square shape, as wide as it is high, with arow of strong setae along posterior and ventral margins, surstylus not protruding beyond shell of epandrium, cerci relatively small and rectangular bearing only afew short setulae. Inner surface of surstylus medially and ventrally covered in fine setulae, antero-ventral corner with approximately 8strong setae in aloose double row, ventral margin of surstylus also bearing amarginal row of strong setae. Phallus two segmented, in lateral view basiphallus abroad tube, distiphallus as long and wide as basiphallus, forming abroad sinuous tube, apex with an outward broad hook, base with alarge rounded lobe.

Differential diagnosis.This species has two katepisternal setae but the surstylus does not bear any prensisetae indicating that it is atrue Lonchaea species and does not belong to the genus Silba Macquart, 1851 . It is unclear whether the two katepisternal setae in the holotype are acharacteristic feature of this species. With bare eyes, uniserial setulae on the anterior part of the genae, black tarsomeres, pale calypteres, asingle seta on the proepimeron and bare orbital plate this species lies near species such as Lonchaea chorea (Fabricus, 1781) in the European fauna. The antennal flagellomere is however much shorter than in L. chorea in which the length to depth ratio is on average 2.0–2.3 to 1(1.7 to 1in L. baechlii ). The frons is wider in L. chorea (Fabricius,1781) with the frons width to eye width ratio ranging from 1 to 1.8–1 to 1.22 (1 to 2.8 in L. baechlii ). This species is however easily differentiated by examination of the male genitalia, in particular the characteristic two segmented phallus. This shows some similarities to the phallus shape in Lonchaea bukowskii Czerny, 1934 and Lonchaea ragnari Hackman, 1956 but both of these species have partly yellow tarsomeres and more than one seta on the proepimeron.

Material examined. Holotype ♁, SERBIA: Goč, 4–7.viii.1980. G. Bächli; deposited in the National Museums of Scotland.

Etymology.the specific epithet refers to the captor of the Holotype.

Figures

Figs 1 – 4. Lonchaea baechlii sp. nov. — 1. Epandrium and associated structures, lateral view. — 2. Same, ventral view. — 3. Internal view of surstylus and associated structure. — 4. Phallus, lateral view.