Chrysotus callichromoides sp. nov.

Runyon, Justin B., 2020, The Dolichopodidae (Diptera) of Montserrat, West Indies, ZooKeys 966, pp. 57-151 : 57

Chrysotus callichromoides sp. nov. Figs 22 , 23

Type material.

Holotype, ♂ labelled: "MONTSERRAT: Woodlands/ Riverside House, 140 ft/ 16°45.985'N, 62°13.341'W / 10-12JAN2002, Malaise/ Ivie, Marske, Puliafico"; "HOLOTYPE/ ♂ Chrysotus / callichromoides / Runyon [red label]" (USNM, type number USNMENT01350613). Paratypes: Montserrat: 2 ♂, 2 ♀, same data as holotype; 1 ♂, same as previous, 5-7 January 2002; 2 ♂, same as previous, 10-13 January 2002, at light; 8 ♂, Cassava Ghaut, Beattie House, 632 ft, 16°45.91'N, 62°12.95'W, 8-17 April 2002, Malaise, A. Krakower; 2 ♂, 1 ♀, same as previous, 17 April-1 May 2002; 1 ♂, same as previous, 17-30 May 2002; 4 ♂, same as previous, 6-12 June 2002; uv light; 10 ♂, 10 ♀, same as previous, 21-30 June 2002, M.A. Ivie; 5 ♂, 7 ♀, same as previous, 14-30 June 2002, Malaise; 5 ♂, same as previous, 24 June 2005, yellow pans, V.G. Martinson; 1 ♂, Rendezvous Bay, 26-31 July 2005, uv light, WIBF group; 1 ♂, Cedar Ghaut, 26-31 July 2005, yellow pans, V.G. Martinson; 1 ♂, Bottomless Ghaut, 5 August 2005, yellow pans, V.G. Martinson; 1 ♂, Old Town, 16°44.795'N, 62°13.711'W, 19 June 2017, J.B. Runyon.

Other material examined.

Dominica: 4 ♂, 1 ♀, St. John Parish, Cabrits National Park, East Cabrits Trail, 15.58564°N, 61.47210°W, 30 May-7 June 2011, Malaise, M.A. & L.L. Ivie. Nevis: 1 ♂, Camps watershed, 17.18972N. 62.57740W, 70 m, Malaise; 1 ♂, same as previous, yellow pans, 25 May 2017, J.B. Runyon; 4 ♂, Recreation ground, 134 m, 17°07.507'N, 62°34.446'W, 31 August 2017, fogging; 2 ♂, Pinney’s Estate, 22 m, 17°08'54.7"N, 62°37'15.8"W, 20 June 2017, fogging. St. Kitts: 2 ♂, Majors Bay, 15 m, 17.22713N, 62.65183W, 20 February-3 March 2017, Malaise. St. Lucia: 5 ♂, 1 ♀, Micoud District, Escap community, 13°49.92'N, 60°53.91'W, 2-7 May 2009, yellow pans, J. Runyon & C. Delphia; 2 ♂, 1 ♀, Micoud District, trail in dry forest, 45 m, 13°49.9'N, 60°53.9'W, 6 May 2009, J.B. Runyon; 7 ♂, 7 ♀, near Micoud, trail to Fond Bay, 15 m, 13°49'48"N, 60°53'42"W, 16-22 May 2009, Malaise and blacklight trap, S.D. Gaimari & A.R. Cline (MTEC, USNM).

Description.

Male (Fig. 22 ). Body length 2.2-2.6 mm, wing length 2.0-2.5 × width 0.8-1.1 mm. Head: Eyes not contiguous below; face only slightly narrowed, at narrowest one-third width of frons at ocelli; face and frons metallic green-blue with yellow-brown pruinosity that is denser along eyes. Palpus black, oval and broadly pointed apically, with sparse silver pruinosity and ca. six yellow-brown to black setae. Proboscis dark brown with fine hairs along margin. Antenna black; first flagellomere short, width ca. 1.5 × length, lower posterior margin rather flat and dorsal margin rounded, slightly receding; arista-like stylus nearly apical, with small pointed projection below insertion. Lower postocular setae white. Thorax: Scutum and scutellum metallic green with distinct violet reflections and sparse light brown pruinosity; setae on scutum pale brown; six pairs of small biseriate acrostichal setae; six pairs of dorsocentral setae, anterior-most pair small; scutellum with one pair of large marginal setae and one pair of small lateral setae. Pleuron metallic bluish green with sparse gray pruinosity; one or two white setae on lower proepisternum. Legs: Coxae dark brown with metallic blue-green reflections and white setae. Femora dark brown with metallic blue-green reflections with yellow apex and yellow to pale brown hairs and setae, with a few small av and pv setae near tips; femur II with four or five small posterior setae on apical one-third. Tibiae yellow with most setae and hairs pale brown; tibia I without distinctive setae; tibia II without distinctive setae except two large ventral setae at apex; tibia III with ad seta near 1/4, smaller pd seta near 1/4, 1/2, and near apex (specimens from St. Lucia usually have another pd seta near 2/5). Tarsi yellow, distal tarsomeres becoming brown, with tarsomere 5 slightly broadened; pulvilli white and slightly enlarged (subequal in size to tarsomere 5), and each leg with just one tarsal claw; tarsomeres I (2-4) ventrally with white pile. Ratios of tibia:tarsomeres: leg I: 25-18-8-6-3-4; leg II: 36-20-9-6-3-4; leg III: 44-16-9-6-4-4. Wing: Hyaline, oblong-elliptical. Costa slightly more thickened than usual between R1 and R4+5. Vein R4+5 nearly straight. Vein M1 curving slightly backwards near apex. Crossvein dm-cu ca. two-thirds as long as last part of CuA1. Calypter yellow with white to pale-brown setae. Halter knob white, stem brownish at base. Abdomen: Broadly cylindrical, gradually tapering, with hairs and setae pale brown to brown. Tergites dark metallic violet (especially in dorsal view), lateral margins and sternites bluish green; marginal setae only slightly larger; tergite VI with numerous small setae. Sternite VIII with small setae, covering hypopygial foramen. Hypopygium (Fig. 23 ) small, dark brown to black, positioned in ventral notch at tip of abdomen. Hypopygial foramen left lateral. Epandrium dark brown, rather deeply emarginated apicoventrally, with triangular ventroapical lobe bearing three small setae; basodorsally with bulbous protuberance that is densely covered with minute hairs. Surstylus elongate, shining brown, with two strong spines at apex. Cercus brown, ovoid with apex somewhat pointed and narrowed at base, with rather dense whitish to pale brown hairs and setae. Phallus simple, narrow, strongly arched, strongly sclerotized but less so near rounded apex; with sheath rather broad throughout, broadened near apex with 4-5 small dorsal teeth along dorsal margin and three black apical spines arching ventrally to overlap phallus, strongly sclerotized except membranous subapically in middle of expanded area.

Female. Body length 2.2-2.6 mm, wing length 2.0-2.4 × width 0.8-1.0 mm. Similar to male, but face less narrowed below with narrowest width two-thirds width of frons at ocelli; clypeus distinct, bulging at suture; first flagellomere with less prominent point below insertion of arista-like stylus; thorax and abdomen dark green with bronze reflections, not violet; femur I usually more yellow at tip; tibia II with large ad seta near 1/5; tarsi with tarsomere 5 not broadened, pulvilli not enlarged, with two tarsal claws; wing with thickening of costa less pronounced.

Etymology.

This species is named for its similarity and presumed relatedness to C. callichromus Robinson.

Distribution.

Dominica, Montserrat, Nevis, St. Kitts, St. Lucia.

Remarks.

Chrysotus callichromoides differs most noticeably from C. callichromus in having a white halter knob and white to pale brown setae on the thorax, legs, abdomen, and calypter (each of these has dark brown to black setae in C. callichromus ). The male genitalia of these two species are very similar, but the phallus sheath in C. callichromus has only one apical black spine (three in C. callichromoides ). The habitat also seems to differ, with C. callichromoides mostly found in low elevation dry forests and C. callichromus in moist ghauts in mesic forests. Chrysotus morrisoni Van Duzee (Virgin Islands) (holotype examined) is also related but differs in the scutum having dense brownish pruinosity (mostly obscuring cuticle) with only very slight violet reflections.

Figures

Figure 22. Chrysotus callichromoides sp. nov. habitus of male holotype, left lateral. Scale bar: 1.0 mm.

Figure 23. Chrysotus callichromoides sp. nov. male terminalia, left lateral. Abbreviations: epand-epandrium; ep lobe-epandrial lobe. Scale bar: 0.1 mm.