Pegomya canariensis Michelsen, 1985

Michelsen, Verner, 2009, Taxonomic revision of the Pegomya meridiana species group (Diptera: Anthomyiidae) including natural enemies of invasive Hypericum spp. (Clusiaceae), Zootaxa 2299, pp. 29-43 : 39-42

3. Pegomya canariensis Michelsen, 1985

Figs. 24–34 .

Pegomya canariensis Michelsen in Michelsen & Báez 1985: 278, figs. 1–5.

Description. Size. Medium; wing length 4.2–4.7mm.

Male. Head (except lower frons to varying extent ochre yellow in teneral individuals), body and legs brownish black to black, covered in dark greyish and brown dusting. Antenna black; palpus black, ochre brown on basal third; prementum shiny black, practically without dusting. Dorsum of thorax with a mat sheen, in posterior view with a faint pattern of three darker stripes; abdomen with narrow, well-defined mid-dorsal dark stripe, caudal segments with a dark sheen through thin dusting. Wing with a dark brown tinge; calypteres greyish white; knob of halter yellow.

Frons at narrowest point 1.5–2.0 times as wide as anterior ocellus; frontal vitta at this point at least 3 times as wide as one parafrontal. Orbital- and interfrontal setulae absent, 6–8 equal-sized frontal setae on lower half of parafrontal. Face short, in profile lying well behind fronto-parafacial angle; parafacial inflexed on lower part, in middle about 0.7 times as wide as postpedicel; gena in profile broad, convex at lower margin, with setae arranged in single row. Postpedicel about 1.7 times longer than broad, rounded apically; arista with minute pubescence. Proboscis short, unremarkable; palpus longer than prementum.

Mesonotal ground-setulae sparse, absent between dorsocentral rows. Distance between presutural acrostichal rows equals their distance to adjacent dorsocentral rows; 3 pairs of presutural acrostichals, middle pair moderately enlarged. Lateral posthumeral seta long; prealar seta two-thirds to three-quarters length of posterior notopleural seta. Proepisternals 2, proepimerals 2(–3); katepisternals 1+2. Vein C setulose ventrally, bare dorsally. Lower calypter about same size as upper calypter.

Fore tibia with 1–2 p-setae; mid tibia with 1 ad-, 1 pd- and (1–)2 p-setae; hind tibia with 1 av-, (2–)3 ad- and 2 pd-setae. Mid femur without av-setae but with pv-setae on basal half; hind femur with full row of avsetae and some pv-setae on basal half.

Abdomen relatively short, depressed, moderately thickened caudally. Tergites III–V without discal setae. Tergite VI bare; spiracles VII absent (as in P. provecta , Fig. 15 ). Sternite V ( Figs. 24, 25 ) and genitalia ( Figs. 26–29 ) distinctive.

Female. Apart from primary sexual differences similar to male, but different as follows: General body colour greyish black rather than black. Frons broad; frontal vitta without pair of crossed setae or setulae, on upper part fully 3 times as wide as each parafrontal which bears 2–3 divaricate orbital setae on upper part. Abdominal tergites III and IV short, together distinctly shorter than long and pointed tergite V that, in addition to spiracles V, also accommodates forwardly displaced spiracles VI at its lateral margins (as in P. meridiana , Fig. 9 ). Oviscapt ( Figs. 30–34 ) long, when fully extended considerably longer than remaining abdomen, strongly modified: Tergites VI–VIII large, folded roof-like along membranous mid-line; tergite VI bare, tergites VII and VIII with posterior bands covered in very short, proclinate spinules. Sternites VI and VII narrow, extensively membranous, but bearing either a pair of setae and some setulae (VI) or a pair of setulae and some short spinules (VII); paired sternite VIII very reduced, each half merely indicated by 2–3 short spinules. Epiproct acutely folded roof-like, also covered in short spinules; hypoproct small, partly membranous, bearing more or less reduced setulae, without usual cuticular pubescence. Cerci short, bladelike, acutely folded roof-like and even fused together apically.

Material examined. CANARY ISLANDS [ ZMUC]. Tenerife: Icod de los Viños, 28.22N 16.43W, 200– 300m, 1 paratype male, 12.iv.1976 (M. Báez). La Gomera: Bco Los Loros, 28.09N 17.16W, 520–770m, 18 males 31.i–7.ii.2008, 4 females 6–7.ii.2008 (V. Michelsen).

Biology. On a trip to La Gomera, one of the western Canary Islands, in January–February 2008 the present author found newly emerged Pegomya canariensis , including the previously unknown female sex, in numbers in Bco Los Loros near at the laurisilva forest zone. An abundant shrub growing in this locality was Canary Islands St. John’s wort ( Hypericum canariense L.), which obviously served as larval host plant, as adult P. canariensis of both sexes were clearly attracted to and could repeatedly be obtained from this shrub. However, it was too early in the season to observe egg laying females on developing Hypericum flowers.

Biological control. Canary Islands St. John’s wort, Hypericum canariense L. ( Clusiaceae ) (e.g., Dlugosch 2008) is a woody shrub endemic to the western Canary Islands. Introduced as an ornamental elsewhere, this noxious plant has occasionally escaped from cultivation. Especially in dry shrublands in California, Hawaii and southern Australia it has become invasive and locally crowds out most other vegetation. As no biological control measures so far have been taken against Hypericum canariense , it might be worth testing the ability of Pegomya canariensis to reduce seed production in alien populations of this aggressive shrub.

Figures

FIGURES 24 – 29. Pegomya canariensis Michelsen, male terminalia. 24, 25. Sternite V. 26, 27. Hypopygium. 28. Pre- and postgonites. 29. Phallus. Same scale.

FIGURES 30 – 34. Pegomya canariensis Michelsen, female terminalia. 30. Oviscapt, lateral. 31, 32. Basal and distal segments of oviscapt, flat-mounted. 33, 34. Distal oviscapt, lateral and dorsal. Different scales for 30 – 32 and 33, 34. Abbreviations: ce = cerci, ep = epiproct, hy = hypoproct, VI – VIII = abdominal segment numbers.

FIGURES 13 – 19. Pegomya provecta (Villeneuve), male terminalia. 13, 14. Sternite V. 15. Asymmetrical pregenital sclerites of segments VI – VIII showing spiracles VI (arrows). 16, 17. Hypopygium. 18. Pre- and postgonites. 19. Phallus. Same scale.

FIGURES 9 – 12. Pegomya meridiana (Villeneuve), female terminalia. 9. Abdominal segments V and VI, right half in internal view showing spiracles V – VII. 10. Oviscapt, lateral. 11. Distal part of same, dorsal. 12. Oviscapt, flat-mounted. Same scale. Abbreviations: ce = cerci, ep = epiproct, hy = hypoproct; sp = spiracle; V – VIII = abdominal segment numbers.