Dasiops Rondani, 1856

Grimaldi, David A. & Triplehorn, Don M., 2008, Insects from the Upper Miocene Grubstake Formation of Alaska, American Museum Novitates 3612 (1), pp. 1-20 : 12-14

Genus Dasiops Rondani, 1856

SPECIMENS: Specimens UAF-GS9 and UAF- GS26 ( figs. 9 , 10 ) are complete and well-preserved wings, 3.5 mm and 5.6 mm long. The wings are so well preserved that even the fine veins that comprise the tiny basal cells are intact.

DISCUSSION: The general facies of the wing is typical of the ‘‘higher’’ (Cyclorrhaphan) flies, among which the wing venation is rather conservative. Some cyclorrhaphan families with extremely distinctive wing features can be immediately dismissed, such as many of the muscoids (the wing does not have a large calypter), Agromyzidae , Chloropidae , Sphaeroceridae , many of the tephritoids, etc. Among all other North American cyclorrhaphan genera, these two wings bear closest resemblance to Dasiops (Lonchaeidae) . This is based on: overall shape of the wing, the large subcostal cell, completeness and close proximity of veins Sc and R 1, closed basal cells bm and cup, and a definite but incomplete vein A 1 +CuA 2. Lonchaeids in general have a rather well-developed calypter for ‘‘acalyptrate’’ flies, but it is possible that some of this region of the wing is not preserved in the fossils. The venation of the two specimens is virtually identical, the only (slight) differences being that the crossveins (r-m and m-cu) in UAF- GS26 are slightly closer to each other, the apex of R 4+5 is slightly more curved toward the apex of M, and the trailing edge of the wing in the distal half is slightly narrower (the tip is narrower). The wing of UAF-GS26 is significantly larger than UAF-GS9 by some 60%, which is extreme for intraspecific variation in acalyptrate flies. Thus, there are probably two species of lonchaeids.

The only account for North America of the genus Dasiops are descriptions of new species by McAlpine (1964). The work unfortunately was not a revision, but some cursory distributional data can be gleaned from it. Dasiops is distributed throughout North America with more than 50 species, some of which extend into the Yukon Territory and Northwest Territories of Canada. Seven species are recorded from Alaska: borealis McAlpine , criddlei McA., lineelus McA., anepsiosus McA., hastulatus McA., and penealbiceps McA. (the last three in the albiceps group). Species of the genus are not differentiated on the basis of wing venation. According to McAlpine, many species of Dasiops breed under the bark of dead or dying conifer trees, usually those attacked by bark beetles ( Curculionidae : Scolytinae ). Biogeography of this genus is similar to Bibio .

The only other, putative fossil lonchaeids to have been described are in Baltic amber ( Hennig, 1967), Glaesolonchea electrica Hennig and Morgea mcalpinei Hennig. However , both have been found to belong to the Pallopteridae ( Morge, 1967; McAlpine, 1981). The Alaskan fossil would be the only fossil lonchaeid.

Order COLEOPTERA Linnaeus, 1758

Two taxa of beetles are represented only by a specimen each and for which only the elytra remain ( fig. 11 ). They are both approximately 5 mm in length and have well-developed striae, but the elytra are distinctly different in structure and thus indicative of two distinct taxa. UAF-GS33 consists of both elytra, which strongly taper to an apical point; the elytra have significant relief, suggesting that the beetle’s body was somewhat dome-shaped. Specimen UAF-GS34 consists of just the left elytron, lateral and medial margins of which are parallel to nearly so, and the elytron is quite flat. Specimen UAF-GS33 is a weevil (family Curculionidae ) and UAF-GS34 is a ground beetle (family Carabidae ) (identifications courtesy of S. A. Elias, personal commun.).

Figures

Fig. 9. Photomicrographs of Lonchaeidae (cf. Dasiops) wings. A. UAF-GS9. B. UAF-GS26.

Fig. 10. Camera lucida drawings of Lonchaeidae (cf. Dasiops) wings. A. UAF-GS 9. B. UAF-GS26.

Fig. 11. Photomicrographs of beetle elytra. A. UAF-GS33: family Curculionidae. B. UAF-GS34: family Carabidae. (Both to the same scale.)