Egle myricariae Grossmann, 1998

Michelsen, Verner, 2009, Revision of the willow catkin flies, genus Egle Robineau-Desvoidy (Diptera: Anthomyiidae), in Europe and neighbouring areas, Zootaxa 2043 (1), pp. 1-76 : 18-20

2. Egle myricariae Grossmann, 1998

Figs. 39–45 , 55, 56 .

Egle myricariae Grossmann, 1998: 324 , figs. 1–17; Griffiths 2003: 2293; Michelsen 2004.

Description. Medium-sized, wing length 4.0–4.5mm.

Male. Head, body and legs extensively covered in dense, light grey dusting; on mesonotum with three faint brown stripes, one delimited by acrostichal setal rows, the others following dorsocentral setal rows; abdomen with distinct mid-dorsal blackish stripe and dark bands anteriorly on tergites II–V. Prementum darkly subshining through thin grey dusting. Fronto-parafacial angle prominent, in line with well well projected lower facial margin. Parafacial in broadest aspect almost 1.5 times width of postpedicel on upper part but downwards narrowed and approaching width of postpedicel. Gena broad, setae usually arranged in two rows. Proboscis moderately long and slender; haustellum about as thick but only ca. 0.55 times as long as fore tibia; palp slender, shorter than haustellum. Proepisternals (1–)2; proepimerals 1–3. Prealar seta ca. twothirds as long as posterior notopleural seta. Lower calypter about half as long as upper calypter. Fore tibia with 0 ad-, 0 pd- and 1–2 p-setae. Mid tibia with 1 ad-, 1 pd- and 2(–3) p-setae. Hind femur with pv-setae only half as long as femoral depth where situated, absent on basal and subapical parts. Hind tibia with 4–7 av-setae and on middle two-thirds a row of 7–10 short pv-setae. Terminalia ( Figs. 39–45 ) very similar to those of E. longirostris , but readily distinguished by differences given under that species.

Female. Differences from male (apart from usual sexual ones): Head and body overall covered in ligher greyish dusting; brown stripes along dorsocentral setal row broader; abdomen without a distinct mid-dorsal dark stripe. Genal setae in single row. Proepimerals 1–2. Hind tibia with 3–5 av-setae. Oviscapt ( Figs. 55, 56 ) long and thick relative to body size: Combination of broad sternites VI and VII, tergite VIII with hind marginal setulae, apically attenuate epiproct with 0–1 pair of setulae in addition to pair of fine setae, and very slender and pointed cerci may separate it from other West Palaearctic species of Egle . Three similar, moderate-sized spermathecae and ducts.

Material examined. AUSTRIA [ ZMUC; paratypes]: Tyrol: Lechtal 1.5km NE Forchach, 900m, on Myricaria , 2 males, 2 females 4.vi.1998 (A. Grossmann); Weissenberg am Lecht , ex larvae in seed capsules of Myricaria , 1 male, 1 female 21.v.1997 (A. Grossmann) .

Biology. The following is extracted from Grossmann (1998) which should be consulted for more details. Egle myricariae was found in numbers on and around the larval host plant, German tamarisk ( Myricaria germanica (L.) Desv.; Tamaricaceae ), a woody shrub growing on open ground along montane and subalpine streams. Its small bisexual flowers are gathered in a tight inflorescence reminiscent of a willow catkin. The seed capsule even embeds the developing seeds in white hair as in Salicaceae . The flight period is synchronized with the flowering and seed development of its host plant and therefore much later than for other European species of Egle using Salix spp. as host plants. The males engage in station-taking behaviour rather than regular swarming. Both sexes feed on excretions from the young leaves as well as nectar and pollen from the flowers of German tamarisk. The eggs are layed singly, typically at the base of a seed capsule at the time when the flower buds are about to open. A single flower may contain more than one egg, but only one larva survives by eating its way into the capsule that is subsequently emptied of developing seeds by the growing maggot. Capsules with grown larvae were collected August 15; most larvae left the capsules 2–6 days later to pupariate rather deep in the underlying substrate. Males first and then females hatch during May from the overwintering puparia in time to start a new generation.

Distribution. Known so far only from Tyrol, Austria.

Relationships. See above under ‘The Egle longirostris species group’.

Figures

FIGURES 39–45. Egle myricariae, male terminalia [paratype: Austria]. 39, 40. Sternite V, ventral and lateral views. 41, 42. Hypopygium, caudal and lateral views. 43. Pre- and postgonites, lateral view. 44. Postgonite, broadest view. 45. Phallus, lateral view. Same scale.

FIGURES 52–56. Egle spp., female terminalia. 52. E. concomitans, oviscapt, flat mounted. 53. Same, distal oviscapt, lateral view. 54. Same, spermathecae. 55. E. myricariae, oviscapt, flat mounted [paratype: Austria]. 56. Same, distal oviscapt, lateral view. Different scales.