Guttipsilopa dianneae Mathis 1997

Guttipsilopa (Nesopsilopa) dianneae

DESCRIPTION.—Moderately small- to medium-sized shore flies, length 2.2–3.6 mm.

Head: Ocellar seta inserted very slightly cephalad of alignment of anterior ocellus; face comparatively wide, face-width to head-width ratio 0.38; arista bearing 4–5 dorsal branches.

Thorax: Scutellum with dorsal surface similar in color to that of scutum, at most, very slightly grayer. Wing generally lightly infuscate, anterior margin conspicuously darker brown, area along veins and crossveins slightly darker, transition from dark anterior margin to lighter coloration gradual but limited to a narrow zone; costal-vein ratio 0.62; M-vein ratio 0.83.

Abdomen: Dorsum subshiny to shiny, brownish black to black, with tergites 1–2 moderately invested with brown microtomentum, appearing more brownish black, brown microtomentum becoming progressively sparser on more posterior tergites, tergite 5 entirely black; sternite 5 of male deeply U-shaped with arms parallel and oriented posteriorly along sides of hypandrium. Male terminalia (Figures 175–177): surstylus (Figures 175, 176) in posterior view long, narrow, slightly sinuate, gradually tapered toward ventral apex, which is acutely pointed, in lateral view shallowly angulate posteriorly.

TYPE MATERIAL.—The holotype male is labeled “BELIZE. Stann Cr[ee]k. Dist[rict]. Twin Cays (Aanderaa Flats) 17–21 March 1988 Wayne N. Mathis.” Paratypes are as follows: BELIZE. Stann Creek District: Coco Plum Cay, 23 Mar 1988, W.N. Mathis (1; USNM); Stewart Cay, 9 Nov 1987, W.N. Mathis (1). The holotype is double mounted (minute nadel in a plastic elastomere block), is in excellent condition, and is deposited in the USNM.

DISTRIBUTION.—Thus far, this species is known only from the type series, which is from the Belizean cays of the Stann Creek District. Undoubtedly the range of this species will be found to be more extensive with better sampling of the shore-fly fauna from adjacent and other localities.

NATURAL HISTORY.—All specimens of the type series were collected by sweeping low-level to shruby vegetation immediately adjacent to the shore.

ETYMOLOGY.—The specific epithet, dianneae, is a genitive patronym to recognize the collecting efforts of my wife, Dianne, while she helped conduct field work in Belize. Her support in general has contributed significantly to my studies of Diptera.

DIAGNOSIS.—This species is very similar to G. umbrosa but can be distinguished by the following combination of characters: fifth sternite more deeply notched, U-shaped with parallel sides (the emargination of the fifth sternite in G. umbrosa extends less than one-half the length of the sternite, and the sides are tapered to a narrower anterior margin); and surstylus gradually tapered toward the ventral apex, which is acutely pointed, rather than becoming broader, as in G. umbrosa.