Megaselia dilatimana, 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 : 5-6

Megaselia dilatimana sp. nov.

( Figs 3–5 )

In the keys of Beyer (1965) this species runs to couplet 27 on page 50, on the basis of the following features. The two species of couplet 27 both have the costal cilia exceeding 0.1 mm in length, but the new species has these cilia <0.1 mm long, and it has a different hypopygium. Additional diagnostic features include the female abdominal tergite 7 being longer than broad and the brown halteres; as the males of subsequently described species running to the same couplet with brown halteres have the mid femur with a ventral bulge and their females have abdominal tergite 7 broader than long ( Disney, 2004b).

Etymology. The name derives from the Latin for dilated hand and refers to the swollen front basitarsus.

Male

Frons brown, with 96–132 hairs, with dense but very fine microsetae and the bristles arranged as Fig. 4 . SAs robust, but lower pair a little weaker and subequal or (more usually) distinctly shorter and finer. Cheek with 4–5 bristles and jowl with 2–3 longer ones. Postpedicels subglobose, brown and without SPS. Palps relatively small, with a short basal segment, straw yellow and with 5–6 bristles and 7–8 hairs. Labrum coloured as palps and about as wide as postpedicel. Labella at most a little darker on top, and with only a few scattered short spinules below. Thorax brown. Mesopleuron with 4–24 hairs and 2–4 (usually 3) differentiated bristles near hind margin. Three notopleural bristles and no cleft in front of these. Scutellum with an anterior pair of hairs (subequal to hairs at rear of scutum) and a posterior pair of bristles. Abdominal tergites brown with short, fine hairs and those at rear of T6 only slightly longer than rest ( Fig. 3 ). Venter brownish grey and with hairs below segments 5–6 that are longer than those on tergites, but those on 3 and 4 are minute and easily overlooked at low magnifications. Hypopygium with brown epandrium, a paler hypandrium, a straw yellow anal tube, and as Fig. 3 . Right lobe of hypandrium vestigial. With two rectal papillae. Legs mainly straw yellow apart from brown on mid coxae and hind femora, but the mid femur and mid and hind tibiae are in part variably lightly tinged brown. Fore tarsus as Fig. 5 , with posterodorsal hair palisade on segments 1–4. Dorsal hair palisade of mid tibia extends up to two thirds of length. Hairs below basal half of hind femur clearly longer than those of anteroventral row of outer half. Hind tibia with 9–15 differentiated posterodorsal hairs. Spinules of apical combs simple. Wings 1.0– 1.2 mm long. Costal index 0.36–0.41. Costal ratios 2.9–5.2: 1.0–1.4: 1. Costal cilia (of section 3) 0.05–0.06 mm long. With 0–2 minute (shorter than width of vein) hairs at base of vein 3. With two axillary bristles, the outer being longer than costal cilia. Sc pale and not reaching R1. Veins yellowish grey, except 7 is obscure and may require critical lighting to be seen. Membrane only very lightly tinged grey. Haltere brown.

Female

Head similar to male but labrum a little wider (typically 1.2–1.4x) than diameter of postpedicel. Thorax as male. Abdominal tergites brown with short, fine hairs and those at rear of T6 only slightly longer than rest. The tergites progressively a little narrower from T2 onwards. T5 about twice as broad as long and T6 about 1.7x as broad as long and without an anteromedian notch but with a shallowly concave front margin instead. T6 almost quadrangular but slightly wider than long, and the median third is variably devoid of pigment. Each outer third bears 7–8 hairs that are at least as long as those at the rear of T7. Venter brown, and with a few hairs similar in size to those on tergites below segments 5 and 6. Otherwise the hairs on segments 3–6 are minute. Sternite 7 an irregular tall, narrow, light brown triangle whose length is about twice the width of the hind margin, which typically bears three longer hairs than the 2–5 situated further forwards. The anterior point is darker than the rest. Posterolateral lobes at rear of sternum 8 not protruding and with three submarginal hairs that are longer than the 3–5 further forward. Epiproct about twice as broad as long and with four long hairs at rear and typically two smaller ones further forward. Cerci pale and at least twice as long a broad. With two rectal papillae. Furca not evident. Dufour’s crop mechanism rounded behind, about 2.5–2.6x as long as broad, and located in the thorax. Legs very similar to male. Wing and haltere as male. The minimal sexual dimorphism in the legs and wings is unusual.

Material

HOLOTYPE male, Seychelles, Silhouette Island, La Passe above mausoleum, 1–4 July 2000, J. Gerlach ( CUMZ, 8–125). Paratypes, 3 males, Silhouette Island, Grande Barbe, Acrostichum marsh and Old village, 2–10 June 2001, J. Gerlach ( CUMZ, 8–136, 137). 1 female, Aldabra, Picard Island, 27–29 September, K, Mach & O. Maurel ( CUMZ, 8–154). 1 female, Oman, Al­Khuwair, 26 February 1988, M. J. Ebejer ( NMW ­ 5­152); 5 males, 6 females, Ruwi Wattayeh, 31 March to 7 April1988, M. D. Gallagher ( CUMZ, NMW ­ 5­145­148). 2 females, United Arab Emirates, Sharjah, light trap, 1–31 January 2005, A. van Harten ( CUMZ, 32–136); 3 males, 2 females, Sharjah Desert Park, light trap, 22 February to 9 March, 21–29 March & 29 March to 6 April 2005, A. van Harten ( CUMZ, 32­133­136); 3 males, Wadi Wurayah, 12–14 April 2005, T. Pape ( CUMZ, 32­ 138­139); 1 female, Fujairah, light trap, 5 March to 6 April 2006, A. van Harten ( CUMZ, 32­132).

Figures

FIGURES 3 – 5. Megaselia dilatimana, male: (3) left face of hypopygium; (4) frons, with bristles represented by their basal sockets only; (5) posteroventral face of front tarsus. Scale bars = 0.1 mm.