Diaphorus robinsoni sp. nov.

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

Diaphorus robinsoni sp. nov. Figs 30 , 31

Type material.

Holotype, ♂ labelled: "DOMINICA: St. John Par./ Cabrits N.P. (malaise)/ East Cabrits Trail/ 15.58564N, 61.47210W / 30MAY-07JUNE 2011/ M.A. & L.L. Ivie"; "HOLOTYPE/ ♂ Diaphorus / robinsoni / Runyon [red label]" (USNM, type number USNMENT01350616). Paratypes: Dominica: 3 ♂, 2 ♀, Clarke Hall, 2-21 March 1964, H. Robinson. Montserrat: 1 ♂, Cassava Ghaut, 877 ft, canopy fogging at dawn, 21 May 2002, K. Marske & J. Boatswain; 1 ♂, Hope Ghaut, 300 m, 16°45.108'N, 62°12.695'W, 20 June 2017, J.B. Runyon (MTEC).

Description (adapted from Robinson (1975), as Diaphorus mundus ). Male (Fig. 30 ). Body length 2.8-3.3 mm, wing length 2.7-3.1 × width 1.2-1.5 mm. Head: Eyes broadly contiguous above antenna, with ommatidia distinctly enlarged on dorsal half. Face distinctly recessed, as high as wide, metallic bluish with slight whitish pruinosity that is densest and brownish along eyes. Frons reduced to a narrow triangle immediately above antennae, covered with dense brown pruinosity. Palpus yellow with black setae, with one distinct large black seta at apex. Proboscis brown. Antenna brown; first flagellomere slightly yellowish basally, rather truncate, ca. 1.5 × as high as long, with small whitish hairs. Arista-like stylus apical, inserted at dorsal corner. Lower postocular setae multiseriate, white. Thorax: Scutum and scutellum bright metallic green with some violet reflections and slight yellowish pruinosity; 5-7 pairs of black biseriate acrostichal setae; five pairs of black dorsocentral setae; scutellum with one pair of large marginal setae and one pair of small lateral setae. Pleuron slightly bluish with denser grayish yellow pruinosity; upper proepisternum with two small brownish setae, lower proepisternum with distinct black seta above coxa I. Legs: Yellow except base of coxa I and all of coxae II and III brown. Hairs and setae black. Coxa I with small black setae on anterior surface and three or four large black setae spaced along distal two-thirds of lateral edge; coxa II with rather long, rather dense setae anteriorly and three larger ad setae; coxa III with large ad seta near base. Femur I with row of pv setae, basal-most seta in this series larger and erect, others progressively longer on distal two-thirds, with row of shorter av setae on basal two-thirds; femur II with both av and pv rows of short setae, pv series more distinct; femur III with longer erect setae in four ventral rows, one av and one pv seta near base stronger. Tibia I with only very small ad seta near 1/5; tibia II with rather large ad seta near 1/5 and smaller ad seta near 1/2, small pd seta near 1/5 and 1/2, distinct ventral seta near 3/4, four apical setae; tibia III with small ad seta near 1/5, larger pd seta near 1/5, 2/5, 3/5, and 4/5, four apical setae. Pulvilli much enlarged on leg I, moderately enlarged on leg II, and scarcely enlarged on leg III. Tarsal claws absent on legs I and II. Ratios of tibia:tarsomeres: leg I: 40-24-8-6-4-6; leg II: 48-28-12-8-4-3; leg III: 64-18-16-12-8-5. Wing: Hyaline, oval, broad at base with well-developed anal lobe. Veins yellow-brown. R1 reaching 2/5 of wing length. R2+3 very slightly flexed, very slightly diverging from R4+5. M1 nearly straight and nearly parallel with R4+5 beyond crossvein. Crossvein dm-cu ca. two-thirds as long as last part of CuA1. Calypter yellow-brown with black setae. Halter knob yellow. Abdomen: Wholly metallic green with strong coppery reflections. Hairs and setae black with some pale hairs on sternites; marginal setae of tergites and those laterally on tergite II 2-3 × as long as background setae. Tergite VI bare. Sternite VIII with four large, stout black setae projecting posteriorly from tip of preabdomen. Hypopygium (Fig. 31 ) small, dark brown, mostly concealed in ventral notch at tip of abdomen. Hypopygial foramen left basolateral, placed near dorsal edge of epandrium. Epandrium dark brown, with rather large finger-like ventroapical lobe bearing one large and one small seta at apex. Ventral lobe of surstylus elongate, rather sigmoid, with ca. six very small socketed setae near apex. Doral lobe of surstylus rather broadly rounded and with three setae. Cercus brown, small, bilobed with each lobe covered in minute hairs and bearing three or four brown setae. Phallus strongly arched, apex round and very slightly flared with several minute inward-facing teeth along lateral margin near apex. Hypandrial arms present, symmetrical, but not external to epandrium. Postgonites bilobed apically, ventral lobe large and hook-shaped, dorsal lobe smaller with pointed lobe immediately ventral to cercus.

Female. Body length 3.1 mm, wing length 3.1 × width 1.4 mm. Similar to male, but face 1.5 × as wide as high; clypeus distinct, forming lower two-fifths of face; front as wide as face with straight sides; face and front bluish with violet reflections; palpus broader, brownish, with apical setae distinct; femora without longer ventral setae; tibia II with small additional ad seta near base, second small ventral seta near 1/3, sometimes with an additional av or pd seta.

Etymology.

This species is named for Harold Robinson who collected and treated this species (as D. mundus Loew) on Dominica.

Distribution.

Dominica, Montserrat.

Remarks.

Robinson (1975) interpreted this species as Diaphorus mundus Loew which was transferred to the genus Chrysotus by Pollet et al. (2004) because it does not fit the definition of Diaphorus proposed by Robinson and Vockeroth (1981). Chrysotus mundus actually belongs to the group containing C. interfrons sp. nov. and C. parvulus . Diaphorus robinsoni sp. nov. is a true Diaphorus and is most similar to D. amazonicus Parent (Brazil) but this species has tergites 2-3 yellow laterally (wholly green in D. robinsoni ) and Diaphorus subsejunctus Loew (Cuba) which has the eyes not meeting above antenna and pale calypteral setae (and thus might not be a true Diaphorus ).

Figures

Figure 30. Diaphorus robinsoni sp. nov. habitus of holotype male, left lateral. Scale bar: 1.0 mm.

Figure 31. Diaphorus robinsoni sp. nov. male terminalia, left lateral. Abbreviations: d sur-dorsal lobe of surstylus; epand-epandrium; ep lobe-epandrial lobe; hypand arm-hypandrial arm; pgon-postgonite; v sur-ventral lobe of surstylus. Scale bar: 0.25 mm.