Sylvenomyia spinigera ( Spungis 1985 ) Spungis, 1985

Penttinen, Jouni & Jaschhof, Mathias, 2009, On the systematics of Sylvenomyia Mamaev & Zaitzev (Diptera, Cecidomyiidae, “ Porricondylinae ”), with the description of a new species from Finland, Zootaxa 2032, pp. 48-54 : 50-52

Sylvenomyia spinigera ( Spungis 1985) comb. nov.

( Fig. 1 B, C)

Chastomera spinigera — Spungis 1985: 46. [Holotype studied.]

Haplusia spinigera — Gagné 2004: 48 [as a consequence of synonymizing Chastomera Skuse with Haplusia Karsch , see Gagné 1978].

= Sylvenomyia sueciae Mamaev & Zaitzev 1998 — Mamaev & Zaitzev 1998: 212. Syn. n. [Holotype not studied.]

Supplement to the descriptions by Spungis (1985) and Mamaev & Zaitzev (1998). Body size 1.1–1.3 mm. Male antenna with 11 flagellomeres; fourth flagellomere with 1 complete, or almost complete, crenulate whorl of long sensory hairs, 1–2 short crenulate rows of sensory hairs ventrally, numerous hair-shaped translucent sensilla distally. In some specimens a vestige of CuA1 present distally. Ventral emargination of gonocoxites U-shaped ( Fig. 1 B), not V-shaped as depicted by Mamaev and Zaitzev (1998: fig. 1d). Gonostylus stout, very slightly curved; apical claw comparatively broad basally ( Fig. 1 B). Membranous cap of ejaculatory apodeme small ( Fig. 1 C). Serration of ventrolateral tegmen margins inconspicuous ( Fig. 1 C).

Remarks on taxonomy. Chastomera spinigera Spungis , of which we studied the holotype, and Sylvenomyia sueciae Mamaev & Zaitzev , which we identified by the original description, are no doubt identical. We may assume that Mamaev and Zaitzev simply overlooked the existence of Chastomera spinigera , as the latter was originally assigned to the Diallactini by Spungis (1985). The wing venation in spinigera is indeed superficially similar to that in Chastomera species, but the outline of the apices of antC and R5 is much different. Also, the male antenna in Chastomera and other Diallactini has 14 flagellomeres, unlike 11 flagellomeres in spinigera . The antennal apices of the holotype of spinigera are broken.

The original description of Sylvenomyia sueciae is misleading in several respects. Tergite 9 was depicted to have an apicomesal invagination ( Mamaev & Zaitzev 1998: fig. 1a), which is no doubt an artifact that occurs when the weak apical margin is folded between the cerci. In our specimens tergite 9 has always a straight apical margin ( Fig. 1 B). The tegmen in the figure by Mamaev and Zaitzev (1998: fig. 1d) is very large, almost as long as the gonocoxites, which ignores the fact that the lateral tegmen walls and the gonocoxal apodemes are separate structures and situated on different levels. In our experience, misinterpretation of artifacts and non-appreciation of the three-dimensionality of structure are common sources of error in the taxonomic work on both porricondylines and lestremiines.

Distribution and phenology. Sylvenomyia spinigera is known to occur in Latvia, northern European Russia, Finland and Sweden. Adults were collected in various forests of the nemoral, boreo-nemoral and boreal (taiga) zone between late May and early July. Larvae are unknown, but we assume they live, possibly exclusively, in the decaying wood of aspen Populus tremula . We base our assumption on the observation that adults of spinigera were repeatedly collected by trunk-emergence traps set over large aspen logs, whereas no specimens were obtained from logs of other tree species, such as Picea abies , Pinus sylvestris , Betula spp., Alnus spp. and Tilia cordata (Jakovlev et al., in prep.).

Material studied. Latvia: holotype male, Koknese, 8 June 1980, V. Spungis. Finland: 13 males, Ta, Lammi, Kotinen Nature Reserve, 61.24 N / 25.06E, 24 May–27 June 2004, J. Jakovlev; 14 males, Sb, Savonranta, Raatelamminsalo, 62.26N / 28.97E, 3 June–3 July 2004, J. Penttinen; 2 males, Kb, Lieksa, Patvinsuo National Park, Autiovaara, 63.08N / 30.37E, 7 July 2004, M. Jaschhof. Russia: 4 males, Karelia, Kondopoga, Kivach Strict Nature Reserve, 62.16N / 33.38E, 11 June–15 July 2005, N. Kutenkova, M. & C. Jaschhof.

FIGURE 2. Sylvenomyia fennica sp. n. A: Male antennal flagellomeres 2–4, ventrolateral view (holotype). B: Male terminalia, ventral view (holotype). C: Apex of gonostylus, dorsal view (specimen from Kittilä, without scale). D: Ejaculatory apodeme and tegmen, ventral view (holotype). Scale = 0.05 mm. 1 = hair-shaped translucent sensilla, 2 = sensory hairs, 3 = setae.

Figures

FIGURE 1. Morphology of Sylvenomyia spp. A: Wing of S. fennica sp. n., dorsal view (holotype, 0.5 mm). B: Male terminalia of S. spinigera, ventral view (specimen from Lieksa, 0.05 mm). C: Ejaculatory apodeme and tegmen of S. s pinigera, ventral view (specimen from Kondopoga, 0.05 mm). acgld = accessory gland duct, antC = anterior portion of costa, antGA = anterior portion of gonocoxal apodeme, cbr = costal break, cerc = cercus, dtrbr = dorsal transverse bridge, memcp = membranous cap, parap = parameral apodeme, postC = posterior portion of costa, postGA = posterior portion of gonocoxal apodeme, vgxbr = ventral gonocoxal bridge.