Menidon Reemer

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 36-37

Menidon Reemer gen. n. Figs 151-156

Type species:

Microdon falcatus Williston, 1887: 9. Type locality: Mexico.

Description.

Body length: 5-10 mm. Small, broadly built flies with long antennae and short, almost round abdomen. Head about as wide as thorax. Face convex; slighly narrower to slightly wider than an eye. Lateral oral margins not produced. Vertex flat. Occiput ventrally narrow, dorsally widened. Eye bare. Eye margins in male parallel, not converging at level of frons, with mutual distance 4 times as large as width of antennal fossa. Antennal fossa about as wide as high. Antenna longer than distance between antennal fossa and anterior oral margin; basoflagellomere longer than scape, sickle-shaped; bare. Postpronotum pilose. Scutellum semicircular; with small calcars or only with pair of small tufts of black microtrichiae posteriorly. Anepisternum without sulcus; pilose on slightly less than dorsal half, bare on slightly more than ventral half. Anepimeron entirely pilose. Katepimeron convex; bare. Wing: vein R4+5 with posterior appendix; vein M1 perpendicular to vein R4+5; postero-apical corner of cell r4+5 rectangular, with small appendix; crossvein r-m located between basal 1/8 and 1/10 of cell dm. Abdomen approximately round, 1 to 1.2 times as long as wide. Tergites 3 and 4 fused. Sternite 1 bare. Male genitalia: phallus straight, furcate near apex, with both processes about equally long; hypandrium without apical part; epandrium without ventrolateral ridge; surstylus furcate, with anterior lobe small and narrow, posterior lobe larger and wider.

Diagnosis.

Basoflagellomere sickle-shaped: curved upward. Anepisternum bare on ventral half. Cell r4+5 with postero-apical corner rectangular. Sternite 1 bare.

Discussion.

This is the only one known taxon among the Microdontinae in which the apical part of the hypandrium is entirely lacking (Fig. 156). Among the Neotropical taxa, this taxon is unique in the sickle-shaped basoflagellomere. The latter character also occurs to some extent in some Nearctic ( Microdon adventitus , Microdon globosus )and Old World taxa (some Archimicrodon , Myiacerapis , Oligeriops Hul, 1937), but these differ from Menidon in several other important characters, such as a furcate phallus (unfurcate in Oligeriops ) and absence of apical part of hypandrium (present in all other Microdontinae ). These morphological singularities, combined with the phylogenetic results of Reemer and Ståhls (in press) (sister of ( Piruwa + Paramicrodon )), are reasons to place Microdon falcatus in its own genus. Thompson (2007) clarified the taxonomy of the type species, which has several synonyms.

Diversity and distribution.

Described species: 1. Central and South America. Unpublished molecular evidence suggests that more than one species is involved, but this needs further study.

Etymology.

The generic name is a combination of the Greek words mene (moon) and odon, with the latter used as a suffix derived from Microdon . The prefix meni- was chosen because of the crescent-shaped basoflagellomere in the type species.