Calyxochaetus angustipennis (Aldrich) Runyon, 2024

Runyon, Justin B., 2024, Revision of the genus Calyxochaetus Bigot (Diptera: Dolichopodidae: Sympycninae), Zootaxa 5539 (1), pp. 1-74 : 12-15

Calyxochaetus angustipennis (Aldrich) comb. nov.

( Figs 15, 25 )

Sympycnus angustipennis Aldrich, 1901: 344 .

Type material examined. LECTOTYPE (designated here to fix identity of the species) ♂, labeled: “ CENT. AMERICA./ Pres. by/ F.D. Godman / & O. Salvin / B.M. 1903–172.”; “Orizaba./ H. H. S. & F. D. G./ Dec. 1887.”; “ B.C.A. Dipt. I./ Sympyncus/ angustipennis,/ Aldr.”; “BMNH(E) #/ 249328”; “ SYNTYPE / Sympyncus / angustipennis / Aldrich/ verified by/ J.E. Chainey, 2001”; “NHMUK 013441950 [with barcode]”; “ SYN- / TYPE [round label with blue margin]”; “ LECTOTYPE / Calyxochaetus / angustipennis (Aldrich) / des. J.B. Runyon [blue label]” (BMNH) [photos examined] . PARALECTOTYPE: Same data as lectotype except, BMNH(E) #/ 249329, NHMUK 013441951 [with barcode] (1♀, BMNH) [photos examined] .

Diagnosis. Males are distinguished from other known species of Calyxochaetus , except C. longitarsus and C. tripilus , by having a long fore tarsomere 1 (as in Fig. 20 ). Males can be distinguished from C. longitarsus by having the mid tarsus modified with several fine, sinuous, yellow anterior setae (as in Fig. 21 ). Calyxochaetus angustipennis is most similar to C. tripilus but differs in having a mostly brown palpus (white in C. tripilus ), a narrower face, and a short and broadly rounded postpedicel (cf. Figs 15 and 16 ). The bare proepimeron found in females of C. angustipennis is shared only with C. tripilus (possibly also with C. longitarsus sp. nov. whose female is unknown).

Description. Male. Wing length ca 2.2 mm. Similar to C. tripilus except as noted: Head: Frons with two large glabrous, shiny violet spots on either side of ocellar triangle (mostly glabrous in C. tripilus ). Face silver-white, narrowly triangular, about 1 ommatidium wide on ventral third.Antenna light brown with scape yellowish ventrally; pedicel yellowish near base; postpedicel ( Fig. 15 ) brown, about as long as wide, with broadly rounded apex. Palpus brown with apex slightly paler. Legs: Midleg: As in Fig. 21 except tarsomere 2 with indistinct swelling at base and with fine sinuous anterior setae confined to basal half (one seta placed just beyond 1/ 2 in C. tripilus ). Wing: Anal area much narrower ( Aldrich 1901, fig. 20). Distal section of M 4 about 3.5X longer than crossvein dm-m.

Female. Similar to C. tripilus except antenna with scape and pedicel mostly yellow; palpus brown with apex pale.

Distribution and seasonal occurrence. Known from one male and one female collected at the type locality of Orizaba, Mexico (Veracruz) in December.

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.