Megaselia fuscamplicosta, Disney, R. Henry L., 2006

Disney, R. Henry L., 2006, Nine new species of Megaselia Rondani (Diptera: Phoridae) from the Seychelles, Zootaxa 1210, pp. 1-25 : 12-14

Megaselia fuscamplicosta sp. nov.

( Figs 11–14 )

In the keys of Beyer (1965) this species runs to couplet 20 on page 50, where one cannot proceed as neither lead applies. However both sexes are immediately distinguished from all the species of this section by the greatly thickened costa.

Male

Frons brown, about as broad as long or a little broader, with 44–54 hairs and dense but very fine microsetae. SAs robust but lower pair weaker and shorter. Upper SAs slightly lower on frons than antials which are as close to the eye margin as the anterolaterals, which are clearly higher on frons. Pre­ocellars further apart than upper SAs, but likewise equidistant or a little further apart than either is from a mediolateral bristle, which is slightly higher on frons. Cheek with 4–5 bristles and jowl with 2 longer ones. Postpedicels subglobose, brown but not dark, without SPS vesicles. Palps pale straw yellow, with 4–5 bristles (the three most apical being the longest) and 2–6 hairs. Labrum coloured as palps but almost twice as wide, but only half as wide as postpedicel. Labella likewise pale and with only a few short spinules below. Thorax brown, being slightly paler on sides. Mesopleuron with 0–7 (mean = 4) hairs and a bristle at rear margin. Three notopleural bristles and no cleft in front of these. Scutellum with an anterior pair of hairs (shorter than hairs at rear of scutum) and a posterior pair of bristles. Abdominal tergites brown with the hairs at rear of T6 a little longer than rest ( Fig. 13 ). Venter pale grey, and with hairs below at hind margins of segments 4–6. Hypopygium brown but not dark, but left lobe of hypandrium and base of anal tube whitish yellow, and as Fig. 13 . Right lobe of hypandrium vestigial. Legs mainly straw yellow, but distal third of hind femur and hind tibia lightly tinged brown. Fore tarsus with posterodorsal hair palisade on segments 1–4, and basitarsus a little thickened and with 2–3 rows of hairs of ventral face reduced to short spinules. Dorsal hair palisade of mid tibia extends about 0.6x the length. Hairs below basal half of hind femur only a little differentiated from adjacent hairs of anterior face and only a little longer than those of anteroventral row of outer half. Hind tibia with dozen differentiated, but fine, posterodorsal hairs. Spinules of apical combs all simple. Wings 1.0– 1.1 mm long and as Fig. 11 . Costal index 0.47–0.49. Costal ratios 1.4–1.9: 1.2–1.7: 1. Costal cilia (of section 3) 0.05–0.07 mm long. No hair at base of vein 3. With two axillary bristles, the outer being subequal to costal cilia of section 1. Sc not quite reaching R1. Veins brownish grey, but 7 is very pale and costa appears dark grey at low magnifications. Membrane tinged grey (just evident to naked eye when viewed against a white background). Haltere brown.

Female

Frons similar to male. Labrum 0.6–0.7x as wide as diameter of postpedicel, otherwise very head similar to male. Thorax as male. Abdominal tergites light brown. T5–T7 as Fig. 14 . Venter pale grey, and with hairs below segments 4–6 and some weaker hairs close to margins of T2–T6. Sternite 7 ill defined and with half a dozen hairs. Posterolateral lobes at rear of sternum 8 broad but scarcely protruding, and with three longer hairs at rear margin and 2–3 shorter ones further forward. Cerci grey and about 2.5–2.6x as long as broad. Neither rectal papillae or furca evident. Likewise I can discern no Dufour’s crop mechanism in the available females. This is probably a case of secondary loss. Legs similar to male but hind femur and tibia more extensively tinged brown, and front basitarsus with only one row of spinules below. Wing 0.9–1.2 mm long, and as Fig. 12 . Costal index 0.46–0.50. Costal ratios 1.4–2.4: 1.2–1.9: 1. Costal cilia 0.05–0.07 mm long. The costa does not appear to be so dark as in male at low magnifications. Otherwise wing and haltere as male.

Gravid females with smooth, thin shelled, eggs that measure only about 0.21 x 0.07 mm. The numbers (with lengths of hind femora in brackets) were 36 (HF = 0.46 mm), 48 (HF = 0.45 mm) and 60 (HF = 0.54 mm).

Material

HOLOTYPE male, Seychelles, Silhouette Island, La Passe, Malaise trap, 10–12 August 2000, J. Gerlach ( CUMZ, 8–118). Paratypes, 2 males, 2 females, as holotype; 1 female, rubber plantation, Malaise trap, 7–10 July 2000, J. Gerlach ( CUMZ, 8­129); 1 female, Jardin Marron, 2000–2001, J. Gerlach ( CUMZ, 8­133); 2 males, 1 female, Grande Barbe mangroves, 19–25 May 2001, J. Gerlach ( CUMZ, 8­135).

Figures

FIGURES 11 – 14. Megaselia fuscamplicosta. (11) male, right wing; (12) female, right wing; (13) male, left face of hypopygium; (14) female, abdominal tergites 5 – 7. Scale bars = 0.1 mm.