Lonchoptera Meigen, 1803: 30

Grimaldi, David A., 2018, Basal Cyclorrhapha In Amber From The Cretaceous And Tertiary (Insecta: Diptera), And Their Relationships: Brachycera In Cretaceous Amber Part Ix David A. Grimaldi, Bulletin of the American Museum of Natural History 2018 (423), pp. 1-97 : 1-97

Lonchoptera Meigen, 1803: 30 .

DIAGNOSIS: Very distinctive gracile, bristly, yellowish to grayish pollinose flies with lanceolate wings and having the following derived features: Male dichoptic; bristles on head long and thick, including long pair of reclinate interfrontals situated very close to anterior margin of frons; vibrissa large, gena with row of 4–5 large, protruding setae; arista preapically dorsal; thorax elongate and shallow, with scutum flattened posteriorly and scutellum near middle of notum, postscutellum very exposed (see Morphology section above for details); tibiae with bristles; male protarsus with ventral denticles. Pretarsus with empodium putatively absent ( Klymko and Marshall, 2008) (SEMs I’ve made of L. bifurcata indicate the empodium may be highly reduced). Wing narrow, lanceolate, apex narrowly pointed, most veins with row of large setulae (except usually R 2+3); R 2+3 –R 4+5 converge very close to wing tip; R 1 very short; venation dimorphic, with female having A 1 +CuA 2 looped and api- cally meeting CuA 1; crossveins dm-cu and r-m absent. Abdomen with tergites I and II fused; spermathecae unsclerotized; surstyli absent.

TYPE SPECIES: L. lutea Panzer, 1809 , by subsequent designation.

COMMENTS: Taxonomy on the approximately 70+ species in the genus has been by regional treatments (Systema dipterorum, 2013). The genus is probably native to the Palearctic, Oriental, Afrotropical, and Nearctic regions, the presence of Lonchoptera bifurcata (Fallén) in Australia and South America almost certainly representing introductions ( Klymko and Marshall, 2008). The distribution of most native species is boreal, restricted to higher latitudes and higher altitudes for more southerly occurrences.

Lonchoptera bifurcata is very common in disturbed habitats throughout the world, particularly grassy, open, even landscaped areas. The species has particular significance in being one of few parthenogenetic Cyclorrhapha. Amongst over 2500 Nearctic specimens examined by Klymko and Marshall (2008), for example, all were females, suggestive of obligate parthenogenesis in North America; the seven known males are all European records, where parthenogenesis is obviously facultative though sex is very rare. The mechanism of parthenogenesis was reported by Stalker (1956) and Ochman et al. (1980) (under the junior synonymic name L. dubia Curran ). Stalker identified four clones based on karyotypes and Ochman et al. (1980) identified nine in the Rochester, New York, area based on isozymes, so some of the chromosomally defined clones have surely diverged by further point mutations. It would be interesting to use DNA sequences to identify further clonal diversity and to determine whether the North American clones are monophyletic. Lonchoptera bifurcata is diploid (2n = 4), and its parthenogenesis is considered a result of chromosomal abnormalities, reflected by the fact that approximately 25% of the eggs do not develop ( Stalker, 1956). Interestingly, the other species of Lonchoptera (all bisexual) that have been examined have metaphase 2n = 6. These obligately bisexual species are more restricted in distribution and habits; larvae where known are saprophagous, and some species are associated with seepages (reviewed in Klymko and Marshall, 2008).