Serichlamys Curran

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 64-66

Serichlamys Curran stat. n. Figs 364-376

Serichlamys Curran, 1925a: 50. Type species: Aphritis rufipes Macquart, 1842: 71, by monotypy.

Description.

Body length: 7-13 mm. Small to medium-sized flies, black, brownish or metallic green, with moderately short to long antennae and oval abdomen. Head about as wide as thorax or slightly wider. Face convex; about as wide as an eye or narrower. Lateral oral margins not produced. Vertex flat. Occiput ventrally narrow, dorsally wid ened. Eye bare or pilose. Eye margins in male converging at level of frons, with mutual distance two to four times as large as width of antennal fossa. Antennal fossa about as wide as high. Antenna shorter to longer than distance between antennal fossa and anterior oral margin; basoflagellomere shorter to longer than scape, oval or slightly sickle-shaped with swollen base, with rounded apex; bare. Postpronotum pilose. Scutellum semicircular; with narrow, elongated calcars, often quite parallel and with small mutual distance, sometimes dorsoventrally flattened. Anepisternum weakly sulcate; pilose anteriorly and posteriorly, widely bare ventrally and medially. Anepimeron entirely pilose. Katepimeron convex; smooth or with wrinkled texture; bare. Wing: vein R4+5 with posterior appendix; vein M1 perpendicular to vein R4+5; postero-apical corner of cell r4+5 rectangular or weakly rounded, always with small appendix; crossvein r-m located between basal 1/5 to 1/3 of cell dm. Abdomen oval, about 1.5 to 2 times as long as wide. Tergites 3 and 4 fused. Sternite 1 pilose or bare. Male genitalia: phallus furcate, with furcation point near apex; hypandrium with basal part bulb-like; epandrium without ventrolateral ridge.

Diagnosis.

Vein R4+5 with posterior appendix. Abdomen oval. Vertex flat. Occiput dorsally (slightly) widened. Postpronotum pilose. Scutellum with calcars. Postero-apical corner of cell r4+5 rectangular, with small appendix. Proepimeron pilose. Anepisternum widely bare medially, also on dorsal half. Anepimeron entirely pilose. Male genitalia: phallus furcate near apex.

Discussion.

Curran (1925a) erected Serichlamys as a subgenus of Microdon , but subsequent authors considered Serichlamys as a synonym of the typic subgenus of Microdon ( Wirth et al. 1965, Thompson 1981b, Cheng and Thompson 2008). Curran (1925a) did not clearly state which characters he considered diagnostic. In his key, Curran keyed out the type species Microdon rufipes (Macquart, 1842) by its eyes being pilose, which was based on a translation of the original description of Aphritis rufipes . Indeed, Macquart (1842) wrote that this species has 'yeux peu velus’ (eyes little pilose). However, examination of the type specimen (coll. OUMNH) revealed that its eyes are bare. Either pile have been wiped off or eroded in the course of time, or Macquart (1842) made an error in his description. Whether Aphritis rufipes has pilose eyes or not, Serichlamys is here recognized as distinct as all included species differ in other characters from Microdon s.s., e.g. postero-apical corner of cell r4+5 rectangular (rounded in Microdon s.s.), phallus furcate apically, hypandrium with bulb-like base.

The differences with Microdon s.s. could be used as arguments for reinstating the subgeneric status of Serichlamys . However, a subgeneric status is contradicted by the phylogenetic results of Reemer and Ståhls (in press), who recovered two Neotropical species of Serichlamys as sister group to Archimicrodon , without apparent close affinities to Microdon . The type species Serichlamys rufipes and Serichlamys scutifer (Knab, 1917) were included in a phylogenetic analysis based only on morphology, and placed in a large and rather uninformative polytomy, but not within a clade containing species of Microdon s.s. For this reason, Serichlamys is here raised to genus level.

Three Nearctic species are included in Serichlamys : Serichlamys rufipes (Macquart, 1842), Serichlamys scutifer (Knab, 1917), and Serichlamys diversipilosus (Curran, 1925). The latter species is included with uncertainty, based only on the description, as no specimens were examined. Two Neotropical species are included: Serichlamys mitis (Curran, 1940) and Serichlamys mus (Curran, 1936). The Neotropical species differ from the Nearctic ones in the shape of the surstylus, which has a long posterior process which is lacking in the Nearctic species. Otherwise the species are very similar. Species of Serichlamys quite similar to the Old World genus Archimicrodon in general habitus and important morphological characters, including the male genitalia. Generally, the antennae of Serichlamys -species are longer and the scutellar calcars are longer.

Diversity and distribution.

Described species: 4 or 5. Nearctic (2 or 3 described species) and Neotropical (2 described species). Several undescribed species from the Neotropical regioan are known to the first author.