Pegomya curviphallis, Michelsen, Verner, 2006

Michelsen, Verner, 2006, A new European species of Pegomya Robineau­Desvoidy (Diptera: Anthomyiidae) near P. flavoscutellata (Zetterstedt), Zootaxa 1257, pp. 49-55 : 50

The Pegomya flavoscutellata species group

In this species group, which equals the ‘ Pegomya flavoscutellata superspecies’ of Griffiths (1984), I recognize three species: P. flavoscutellata ( Zetterstedt, 1838) , P. flaviantennata Griffiths, 1984 and P. curviphallis , new species. The group is defined primarily by one strong synapomorphy, the characteristically sickle­shaped male distiphallus.

Only colour and minor morphological differences distinguish species of the P. flavoscutellata species group. Pegomya flavoscutellata is a widespread Holarctic species (see Michelsen 2004; Griffiths 1984; Fan 1988), which is locally abundant. Pegomya flaviantennata , according to Griffiths (1984), is morphologically almost indistinguishable from P. flavoscutellata , but rather differently coloured. It occurs locally in eastern North America, where its range overlaps with that of P. flavoscutellata . The third taxon of this species group is P. curviphallis , a new species from northern Europe. It also stands very close to P. flavoscutellata , both in colour and morphology, but deviates significantly in the shape of the male distiphallus.

Description. The following combination of characters should enable recognition of both sexes of the P. flavoscutellata species group from other species of Pegomya :

Medium­sized, wing length 3.7–5.5 mm. Colour: Antennal scape, pedicel and basal part of postpedicel orange­yellow. Palpus entirely yellow. Setation on lower part of head all dark coloured. Legs yellow with brownish yellow tarsi, often blackish infuscated posteriorly on fore femur and narrowly at tips of mid and hind femora. Head: Female frons in general with well­developed pair of interfrontal setae; only 2 pairs of orbital setae, both reclinate. Genal setae arranged in single row. Thorax: Distance between rows of acrostichal setae equals distance between acrostichal and dorsocentral rows, except wider apart at neck region and here with some setulae between acrostichal rows. Prealar seta shorter than posterior notopleural seta. Wings: Vein C bare dorsally. Calyptrae subequal in size, lower calypter thus slightly projecting behind upper calypter, especially in males. Legs: hind tibia with 2 ad and 2 pd setae.

Male abdomen: Parallel­sided, dorso­ventrally depressed, barely expanded caudally; tergite VI bare. Sternite V ( Fig. 1 ) unremarkable. Surstyli ( Figs. 2–3 ) distally obtuse and furrowed, apical incision very tight. Pregonite ( Fig. 4 ) broad with one setula on top of anterior process and two very close­set setae on posterior prominence; postgonite ( Fig. 5 ) with one setula on distal third. Distiphallus ( Figs. 6–7 ) slender, characteristically sickleshaped, serrated on paraphallic processes.

Female abdomen: Oviscapt ( Figs. 8–9 ) thick basally, but very slender distal to segment VII; tergite and sternite VI large, extensively pruinose and abundantly setose; tergite and sternite VII abundantly but finely setose; tergite and sternite VIII with strongly reduced setosity; epiproct strongly attenuate, with 1(–2) pairs of fine setae; hypoproct slender, smooth, with a pair of apical setulae; cerci slender, somewhat depressed, with freely projecting apices very reduced and bearing short setae.

Figures

FIGURES 1 – 5. Pegomya curviphallis sp. nov., male. 1. Sternite V. 2. Hypopygium, caudal. 3. Hypopygium, lateral. 4. Pregonite. 5. Postgonite. Scale = 0.25 mm.

FIGURES 6 – 7. Pegomya spp., male, phallus. 6. P. curviphallis sp. nov. 7. P. flavoscutellata (Zetterstedt). Scale = 0.25 mm.

FIGURES 8 – 9. Pegomya curviphallis sp. nov., female: 8. Oviscapt, flat mounted. 9. Oviscapt, distal part. Scales = 0.5 mm (8); 0.25 mm (9).