Terocelion, Ševčík, 2012

Ševčík, Jan, 2012, Terocelion gen. nov., a new Oriental genus of Keroplatidae (Diptera) with pectinate antennae, Acta Entomologica Musei Nationalis Pragae 52 (2), pp. 495-503 : 496-499

Terocelion gen. nov.

Type species. Terocelion terezae sp. nov., here designated.

Diagnosis. Head relatively narrow in lateral view (the ratio of height to width is 5: 3). Antenna long (at least 1.5 times as long as the head and thorax together), pectinate, with 14 flagellomeres. Compound eyes distinctly emarginated above the bases of antennae. Three ocelli, the median one much smaller, the lateral one almost touching the eye margin. Face narrow (three times as high as broad) and bare. Mouthparts reduced, palpus with one visible segment.

Scutum weakly arched. Mediotergite distinctly protruding. Subscutellar membranous area well developed, in the shape of a narrow sagittal triangle, tapering posteriorly and reaching the posterior edge of mediotergite. Both mediotergite and laterotergite bare. Wing distinctly marked and relatively narrow (ratio of length to width 2.8). Sc short, reaching only to the base of R-M fusion. Vein C produced beyond R 5 to about half the distance between the tips of R 5 and M 1. R 4 ending on C. CuA 2 distinctly downcurved towards the tip. A 1 strong, ending just before the wing margin. Tibial trichia in regular rows throughout the entire length of all tibiae, only hind tibia ventrally with a longitudinal area of dense trichia not arranged in rows. Tergite 9 subtriangular, about as broad as long. Gonostylus simple, without teeth, dorsoventrally flattened and apically rounded.

Differential diagnosis. The new genus is probably related to the Holarctic Rocetelion Matile, 1988 and the Afrotropical Paracerotelion Matile, 1974 , especially if we consider the structure of the male terminalia. The dorsoventrally flattened gonostylus without teeth is a distinct synapomorphy of these genera, which form a monophyletic branch in the phylogenetic tree by MATILE (1990: 532). Terocelion gen. nov. differs from these genera mainly in the following characters: male antennae long, 1.5 times as long as the head and thorax together, and pectinate (as long as the head and thorax together, flagellomeres only flattened in both Rocetelion and Paracerotelion ), subscutellar membranous area well developed (absent or small), wing distinctly marked on most of surface (darkened mainly in the distal third), vein C produced beyond R 5 to about half the distance between the tips of R 5 and M 1 (only to about a quarter), A 1 not reaching wing margin (reaching), vein Cu 2 distinctly bent downwards (almost straight), tibial trichia in regular rows throughout the entire length of all tibiae (only on apical half).

Terocelion gen. nov. also resembles the Oriental and Australasian genus Euceroplatus Edwards, 1929 , from which it can be distinguished by the long and pectinate antennae, strongly protruding mediotergite with a distinct triangular membranous area and mainly by the dorsoventrally flattened and rounded gonostylus. The genera with pectinate antennae, like Ctenoceridion and Platyroptilon , differ in the broader head in lateral view, shorter antennae, relatively broad and short wings, longer Sc (reaching above or behind the distal end of R-M fusion) and in gonostylus either bifid or with apical tooth.

Etymology. The name is an anagram of Cerotelion and Rocetelion . Gender is neuter.