Thompsodon Reemer

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 70-71

Thompsodon Reemer gen. n. Figs 406-416

Type species:

Thompsodon conspicillifrons Reemer spec. n. Type locality: Costa Rica.

Description.

Body length: 8 mm. Moderately slender flies with long antennae and basally constricted abdomen. Face in profile slightly convex, almost straight; laterally weakly depressed, therefore slightly carinate dorsomedially; about as wide as an eye. Lateral oral margins not produced. Frons laterally with round, concave areas, filled with dense golden pile, ventrally delimited by a sharply defined ridge. Vertex irregularly swollen. Occiput narrow ventrally, strongly widened dorsally. Eye bare. Antennal fossa about as high as wide. Antenna longer than distance between antennal fossa and anterior oral margin; basoflagellomere about as long as scape; elongate, with dorsal margin straight and ventral margin convex, apex slightly acute. Postpronotum pilose. Anepisternum with shallow sulcus; entirely long pilose. Anepimeron entirely pilose. Katepimeron weakly convex; bare; with wrinkled texture. Scutellum semicircular, weakly triangular; without calcars. 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 around basal 1/7 of cell dm. Abdomen constricted at tergite 1, narrowest at tergite 1, widest at posterior margin of tergite 3. Tergites 3 and 4 not fused, able to articulate independently.

Diagnosis.

Frons laterally with round, concave areas, filled with dense golden pile, ventrally delimited by a sharply defined ridge. Transverse suture complete. Tergites 3 and 4 not fused.

Discussion.

The only known specimen representing this genus has some characters that are not often found among Microdontinae : mesonotal transverse suture complete, tergites 3 and 4 not fused. The lateral concave and densely golden pilose areas on the frons, which are ventrally delimited by a sharply defined ridge, are even unique within the subfamily. The unfused tergites 3 and 4 may suggest affinity with the Neotropical Ceratophya or the Oriental Kryptopyga , whereas the complete trans verse suture reminds of Ceratrichomyia and Indascia . However, the specimen does not agree with the diagnoses of any of these genera, so a new genus seems the best way to make sure that this singular taxon will get the attention it deserves in future studies on the taxonomy of Microdontinae . Hopefully, male specimens will be collected in the near future, which can be used for study of the male genitalia and molecular analyses.

Diversity and distribution.

Described species: 1. Only known from Costa Rica.

Etymology.

This genus is dedicated to Dr. F. Christian Thompson, in acknowledgement of the valuable work he has done on the taxonomy of the Syrphidae in general, and the Microdontinae in particular.