Calyxochaetus tripilus (Van Duzee, 1929)

Runyon, Justin B., 2024, Revision of the genus Calyxochaetus Bigot (Diptera: Dolichopodidae: Sympycninae), Zootaxa 5539 (1), pp. 1-74 : 12

Calyxochaetus tripilus species group

Diagnosis. The tripilus species group is defined by a long fore tarsomere 1 in males that is 1.5X longer than tarsomere 2 ( Figs 20, 22 ). In all other species of Calyxochaetus , males have a short fore tarsomere 1 (less than or equal to length of fore tarsomere 2). A bare proepimeron in females could be another defining characteristic of this group (female of C. longitarsus sp. nov. is unknown). The shiny, glabrous frons will distinguish males and females of this atypical species group from similar sympycnine genera (e.g., Sympycnus ).

Remarks. This species group includes C. angustipennis , C. longitarsus sp. nov. and C. tripilus (Van Duzee) and differs from other species of Calyxochaetus since males have an unmodified fore tarsomere 1 and females have a bare proepimeron (at least in C. angustipennis and C. tripilus ). However, these species are retained in Calyxochaetus because they share most other characters with the genus, including those of the male genitalia, which are indistinguishable from the other species of the genus.

Figures

FIGURES 13–25. Calyxochaetus tripilus species group. 13. C. tripilus (Van Duzee), male habitus. 14. C. tripilus, female habitus. 15. C. angustipennis (Aldrich), male antenna, lateral view (photo by Duncan Sivell, © Trustees of the Natural History Museum, London). 16. C. tripilus, male antenna, lateral view. 17. C. longitarsus sp. nov., male antenna, lateral view. 18. C. tripilus, male head, anterodorsal view. 19. C. tripilus, male wing. 20. C. tripilus, male fore tarsus, ventral view. Arrow shows fore tarsomere 1. 21. C. tripilus, male mid tarsus, ventral view. 22. C. longitarsus sp. nov., male fore tarsus, anterior view.Arrow shows fore tarsomere 1. 23. C. longitarsus sp. nov., male mid tarsus, ventral view. 24. C. longitarsus sp. nov., habitus of male holotype. 25. Known geographical distributions of C. longitarsus sp. nov. and C. tripilus. Scale bars = 1.0 mm.