Egle groenlandica, Michelsen, 2009

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 : 44-45

14. Egle groenlandica sp. nov.

Figs. 187, 188 .

Egle sp. ; Griffiths 2003: 2318; Michelsen 2006: 109. For further references, see Michelsen (2006).

Egle material of some 100 specimens is available from Greenland ( Michelsen 2006). It consists of females only belonging to a single species, which suggests that males are either absent or extremely rare. If so, this might be the first documented case of parthenogenetic reproduction among calyptrate flies. During the present revisional study I have been able to identify the females of practically all European species of Egle , which include several with Holarctic distributions, but without finding any matching the females found in Greenland. It is generally not advisable to formally name and describe new species of Anthomyiidae on the basis of females only, but I make an exception in the present case, because a possibly parthenogenetic species of Egle is fundamentally interesting and very likely will generate further inquiry.

Etymology. The specific epithet ‘groenlandica’ is Latin for ‘from Greenland’.

Description. Male. Unknown or not existing.

Female. Very small, wing length 2.7–3.7mm. Resembling E. inermis but different as follows: Prealar seta longer, about same length as posterior notopleural seta. Scutellum frequently without minute setulae beneath tip. Oviscapt ( Figs. 187, 188 ): Sternites VI and VII narrower and more extensively membranized on posterior parts. Epiproct, sometimes even hypoproct, without any setulae. Cerci longer and more slender. Spermathecae two normal-sized, very elongate and cross-wrinkled; third spermatheca absent but rudimentary duct retained.

Material examined. Type material [ ZMUC]: GREENLAND: Narssarssuaq , 61.10N 45.25W, 3 females (including holotype) 20.vi.1983, 1 female 5.vii.1983 (P. Nielsen). Jameson Land, 1 female 14.vii.2001 (H. Björnsson). Mestersvig, 2 females 1.vi.1953, 2 females 9.vi.1953 (C. Vibe). Lakseelv, Laksefjeld, 2 females 7.vii.1951 (C. Vibe). Godhavn, 1 female 22.vi.1968 (J. Böcher). Other material [ ZMUC] : GREENLAND: Narssarssuaq , 61.10N 45.25W, 30 females 13.vi–5.vii.1983 (P. Nielsen). Jameson Land, 9 females 14.vii.2001, 10 females 22–23.vii.2001 (H. Björnsson). Godhavn, 1 female 1.vii.1968, 1 female 15.vii.1969 (J. Böcher). Diskofjord, Disko Isl., 4 females 23.vii.1982 ( T. Pape). Mestersvig, 18 females 31.v–5.vii.1953 (C. Vibe). Lakseelv, Laksefjeld, 3 females 7.vii.1951 (C. Vibe). Hekla Havn, 5 females 19.vi–30.vii.1892 (H. Deichmann). Gåselandet, 7 females 7–12.vii.1892 (H. Deichmann) .

Biology. Egle groenlandica undoubtedly has seed-feeding larvae developing in female catkins of willow. The genus Salix is an important element in the Greenland flora with five species and some hybrids ranging from erect shrubs as in Greyleaf willow ( Salix glauca L. var. callicarpala (Trautv.) Argus ) and its hybrids, to dwarf, prostrate shrubs as in Arctic willow ( S. arctica Pall. ), Northern willow ( S. arctophila Cock. ex Heller ), Snowbed willow ( S. herbacea L.), Net-leaved willow ( S. reticulata L.) and Bearberry willow ( S. uva-ursi Pursh ). Several of these willow species may serve as host plants for E. groenlandica .

Distribution. Found in all districts of Greenland (NW, SW, S, SE, NE) except for the high arctic N Greenland. Credibly, Egle groenlandica occurs even in adjacent parts of Canada as already suggested by Griffiths (2003) who noticed some apparently identical females in Canadian samples.

Relationships. A morphology-based assessment of the relationships of E. groenlandica within the Egle minuta section is difficult because of the apparently unattainable male sex. It is tentatively included in the E. steini species group because of its overall similarity with E. inermis and allied species.

Figures

FIGURES 187–190. Egle spp., female terminalia. 187. E. groenlandica, oviscapt, flat mounted [paratype: Greenland]. 188. Same, spermathecae. 189. E. setiapicoides, oviscapt, flat mounted [paratype: Uzbekistan]. 190. Same, spermathecae. Different scales.