Grallipeza grenada Marshall, 2013, new species

Grallipeza grenada new species

Figs. 25–27

Description: Size approximately 8 mm. Colour: Head, including frontal vitta, antenna, clypeus and palpus, almost entirely orange with only ocellar triangle black. Fore femur orange to orange-brown; fore tibia dark brown, apex pale with pale setulae; fore tarsomere one yellow-white with pale setulae, tarsomeres 2–5 grey-white with black setulae. Hind femur uniformly pale; tarsomere one of hind leg yellow except at apex, distal tarsomeres pale brown. Katepisternal bristles golden, pleuron entirely orange. Halter yellow with knob brown. Wing with infuscated area expanded into a rounded, club-like discal band extending from R2+3 to base of CuA1. Apex of wing lightly infuscated.

Head: Arista long-haired at least over basal ¾, hairs approximately 0.5 times scape width (Fig. 25). Pedicel with long ventroapical bristles, one almost as long as first flagellomere. Lunule subequal to scape width, with small black bristles. Palpus orange, convex ventrally with short dark bristles on ventral half. Frontal vitta broad and parallel-sided (Fig. 26). Only one fronto-orbital bristle (the upper, or orbital; the two lower, or frontal, bristles are absent; Fig. 26).

Thorax: Cervical sclerite slightly convex ventrally, microtrichose. Fore femur with an anterior row of about 12 and a posteroventral row of about 10 stout bristles along length. One distinct dorsocentral bristle. Postpronotum prominent, with scattered dark setulae mostly restricted to anteroventral region; one large and 1–2 small suprahumeral bristles (Fig. 26). Wing: Anal cell microsetulose except for a narrow longitudinal strip.

Male abdomen: (no dissection available) Pleuron mostly black, segment 2 with an elongate-oval pale area (type specimen shriveled but this is presumably eversible as a dome in fresh material). Tergites 1–4 dark, pollinose and densely setulose; tergite 5 shining and sparsely setulose; tergite 6 black and shining bare (Fig. 27). Epandrium elongate and yellow, 2.3 times as long as high. Genital fork with arms strongly incurved, almost entirely enclosing a circular area; mesal surface with multiple (about 30) stout black bristles forming a double row.

Type material: Holotype (male, USNM): “ Grenada BWI FM Root” “Gouyave Grenada 19.vii.1929 ”. Other material examined: One female labeled “Tivoli W. I. 11-7-44, H. Stehle, 44-18070” “USN3 167286”, “ Grallipeza nebulosa James (Lw) ” possibly belongs to this species, but it is too badly damaged to treat as a paratype. It is missing the head, the tip of the abdomen, midlegs, the right foreleg and most of the scutum (including the part normally supporting dorsocentral bristles). The fore femur lacks the ventral bristles found on the male holotype of this species; no other species is known to be sexually dimorphic for this character. The abdominal pleuron is pale with the exception of a dark dorsal area adjacent to the tergites.

Comments: Grallipeza grenada is clearly distinct from Caribbean congeners on the basis of thoracic chaetotaxy, leg colour and the male genital fork, and confirms the general pattern of island-level endemism of West Indian Grallipeza. It seems most similar to the St. Vincent species G. m e l l e a, from which it differs in having only a single pair of dorsocentral bristles. These two species are the only Caribbean Grallipeza with ventral femoral bristles and with a double row of mesal teeth on the genital fork.

Etymology: Grallipeza grenada is (obviously) named for its type locality.