Sympycnus montserratensis sp. nov.

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

Sympycnus montserratensis sp. nov. Fig. 32

Type material.

Holotype, ♂ labelled: "WEST INDIES: MONTSERRAT/ Katy Hill (top), 730 m/ 16°45.731'N, 62°11.646'W / 28 JUNE 2017, J.B. Runyon"; "HOLOTYPE/ ♂ Sympycnus / montserratensis / Runyon [red label]" (USNM, type number USNMENT01350617). Paratypes: Montserrat: 1 ♂, 6 ♀, same data as holotype (MTEC, USNM).

Description.

Male (Fig. 32A ). Body length 2.2 mm, wing length 2.2 × width 0.8 mm. Head: Eyes essentially contiguous below, face very narrow throughout (most of face ≤ width of one ommatidium), very slightly widened near mouth and narrowly triangular immediately below antennae, dark brown with thick brown-gray pruinosity. Frons and occiput dark brown with dense brown-gray pruinosity. Palpus very small, narrowly oval, dark yellow with two small black setae near apex. Proboscis brown, with fine brown hairs along margin. Antenna (Fig. 32C ) with scape and very base of first flagellomere yellow, remainder brown; first flagellomere broadly triangular with rounded apex, as long as high; arista-like stylus arising from middle of dorsal edge. Lower postocular setae longer, whitish, upper postocular setae black. Thorax: Scutum and scutellum yellow-brown with black setae; acrostichal setae absent; six pairs of dorsocentral setae, 5th and 6th pairs smaller, 5th pair slightly out of line; scutellum with one pair of large marginal setae and one pair of minute lateral hairs. Pleuron and metepimeron yellow, anepimeron with small black triangular area below wing insertion; proepisternum with two small, fine pale setae. Legs: Yellow, except coxa II with small brown streak at insertion of ad seta and small black posterobasal spot; tarsi becoming faintly brown distally. Anterior surface of coxa I with short yellow to brown setae becoming larger distally and ca. five black setae across apex. Femur I with small subapical pv seta; femur II with subapical anterior and pv seta; femur III with subapical anterior seta. Tibia I without distinctive setae; tibia II with ad seta near 1/3 and 2/3, pd near 1/5, pv near 2/3, and 4 apical setae; tibia III with ad seta near 1/5, and small rather indistinct pd seta just before 1/5, 2/5, just beyond 1/2, near 2/3, and 4 apical setae. Tarsus I (Fig. 32B ) with tarsomere I(1) bearing two longer slender distally-curved ventral setae in basal half and a slightly shorter such seta at apex, and series of ca. 4-6 very short slender more erect ventral setae scattered along length (two near base most distinct). Ratios of tibia:tarsomeres: leg I: 32-18-9-4-2-3; leg II: 45-22-10-8-5-4; leg III: 58-12-16-10-6-5. Wing: Surface brownish tinged, slightly darker brown anteriorly, with dark brown veins; narrowly elliptical without anal lobe. R2+3 essentially straight. R4+5 distinctly arching backward and slightly convergent with M1 near apex. M1 arching backwards slightly near apex, ending in wing tip. Crossvein dm-cu two-thirds as long as last part of CuA1. Calypter brown with fan of rather long yellow to light brown setae. Halter knob brownish yellow and stem yellow. Abdomen: Cylindrical, slender, longer than thorax, with black setae. Tergites dark brown dorsally, except tergite I (and sometimes part of tergite II) yellow-brown dorsally; tergites I-V broadly yellow laterally; tergite 6 wholly dark brown. Sternites yellow. Abdomen without metallic reflections. Hypopygium very small, dark brown, mostly concealed in tip of preabdomen, not dissected. Cerci brown, narrowly triangular (twice as long as wide), covered with short brown hairs with longer nearly white hairs at apex.

Female. Body length 2.2-2.3 mm, wing length 2.2-2.3 × width 0.8-0.9 mm. Similar to male, but face broader (one-third width of frons), parallel-sided, upper face with gray pruinosity, clypeus with gray-brown pruinosity; palpus larger, dark yellow to nearly brown with white tip; dorsum of thorax more yellow with scutellum brown; tarsus I unmodified, but tarsus I(1) usually with one very short slender curved ventral seta evident at base; abdomen generally more yellow, curved downward when dry.

Etymology.

This species is named for the island of Montserrat.

Distribution.

Montserrat.

Remarks.

Sympycnus montserratensis is related to S. dominicensis Robinson (Dominica) but differs most notably in color of the thorax (yellow-brown in S. montserratensis , brown in S. dominicensis ) and form of front tarsus in males (e.g., position of slender curved ventral setae and relative length of tarsomeres; cf. Robinson 1975: fig. 194). Specimens were taken by sweeping shaded moist leaf-covered ground in elfin woodland on the top Katy Hill (Fig. 2C ).

The hypopygium was not dissected to preserve intact the two male specimens and because male terminalia in Sympycninae frequently offer no reliable characters to separate species within a genus (e.g., Hurley and Runyon 2009; Evenhuis 2012; Runyon 2012).

Figures

Figure 2. Some Montserrat landscapes and habitats A Soufriere Hills Volcano, view from Old Towne, June 2017 B northeast view from Katy Hill into Bottomless Ghaut C elfin woodland on top of Katy Hill, at the highest elevations of the Centre Hills. Photographs by Justin Runyon.

Figure 32. Sympycnus montserratensis sp. nov. male A habitus of holotype, left lateral B tarsus I, posterior view, arrows indicate slender distally-curved ventral setae C male antenna, medial view. Scale bars: 0.5 mm (A), 0.25 mm (B, C).