Bolitophila, Meigen, 1818

Greenwalt, Dale E. & Blagoderov, Vladimir A., 2019, Review of the fossil record of Bolitophilidae, with description of new taxa and discussion of position of Mangas Kovalev (Diptera: Sciaroidea), Zootaxa 4567 (3), pp. 546-560 : 558

“ Bolitophila ” pulveris Lewis, 1969

( Figure 11 )

Holotype. UCM # 28420 housed in the Colorado University Museum of Natural History, Boulder, Colorado. Type locality and horizon. Juliaetta , Idaho; Latah Formation , Miocene.

Collected from the Early to Middle Miocene Latah Formation in northwestern Idaho, Bolitophila pulveris was described by Lewis (1969) based on a poorly preserved and incomplete wing, part and counterpart, with portions of some veins not preserved and others dislocated (Figure 11.1). Assignment of the fossil to the genus Bolitophila was largely based on the presence of a stigma “limited distally by R 2+3 ”. In the present study, the fossil itself has been reexamined. R 1 appears to terminate in the costa within the distal portion of the distinctly pigmented stigma. R 2+3 appears to be either absent or not preserved or, as reported by Lewis (1969), at the distal boundary of the stigma. The distal boundary of the stigma (Figure11.4) appears to be more pigmented than the interior of the stigma, as it is in some extant species of Bolitophila (e.g. in B. aperta and B. basicornis [Kjaerandsen, personal commun. 2016]), and this may be the basis of Lewis’ original interpretation of R 2+3. Other veins are as described by Lewis (1969) (Figures 11.1, 11.2); However, crossvein bm-cu is absent and the origin of CuA is very close to crossvein r-m (even with the midpoint of R S). Bechev and Chandler (2011), based on Lewis’s original illustration of the wing, cited the absence of crossvein bm-cu and concluded that this specimen is “typical for the family Mycetophilidae ”. The family Bolitophilidae is defined, in part, by the presence of bm-cu or the fusion of M and CuA, “far below the level of base of Rs” ( Vockeroth 1981). Hence, the lack of the crossvein bm-cu, the very distal position of the posterior fork and the questionable presence of R 2+3 confirm the conclusion of Bechev and Chandler (2011) and B. pulveris cannot belong to Bolitophilidae . An alternative interpretation might be that the line designated on fig. 11.1 as CuA is, in fact, not a vein, but a margin of anal lobe of the wing folded over M and CuA bases, which remain obscured. In this case the wing may possess bm-cu, and thus, B. pulveris might be a true Bolitophilidae . Until further material is found we prefer to consider this specimen as Sciaroidea incertae sedis.

Figures

FIGURE 11. Bolitophila pulveris Lewis, 1969, UCM # 28420. 1. Wing (counterpart) 2. Wing (part). The three arrowheads trace the origin (far left) and path of CuA 1. 3. Stigma (counterpart). 4. Stigma (part). 5. Drawing of wing. Scale bars equal 1 mm (1, 2) and 0.4 mm (3, 4).