Polyphagy on unpredictable resources does not exclude host specialization: insects feeding on mushrooms.

The degree of ecological specialization plays a crucial role in shaping the structure and functioning of communities. However, comparing specialization within and among groups of organisms is complicated by both methodological issues and conceptual and terminological inconsistencies. Environmental predictability has been considered a key determinant of specialization though empirical evidence is still limited. Fungi and their insect consumers provide a poorly studied but promising system to measure host specialization and test the predictability hypothesis. In this study, we systematically sampled mushrooms in North European boreal forest, and reared total samples of fungivores colonizing the fruitbodies. Due to the unpredictable nature of mushrooms as a resource, low levels of host specialization can be predicted for these insects, which have indeed widely been considered polyphagous. Contrary to expectations, the majority of the studied fungus gnats were found not to exploit their host taxa indiscriminately. Not only were some mushroom taxa never colonized, the infestation rate of acceptable hosts also differed in most of these fungivores. Gnat species themselves formed continua with respect to the estimates of the degree of specialization, derived from parametric individual-based analyses of presence-absence data. In most cases, host use was best explained by models in which the hosts were classified at genus level, with limited support to specialization to particular host species, families, or orders. Indeed, most of the common fungivores appeared to preferentially use various species from one or a few mushroom genera while occasionally feeding on members of other host taxa. This pattern has likely evolved as a compromise between selective forces stemming from host unpredictability and taxon-specific chemical profiles of the mushrooms. Our study highlights the multidimensional nature of ecological specialization: a high number of acceptable hosts does not preclude considerable discrimination among members of the available resource pool. Such situations can only be revealed by individual-based analyses capable of capturing differences in partner-to-partner interaction intensities.

Review of the fossil record of Bolitophilidae, with description of new taxa and discussion of position of Mangas Kovalev (Diptera: Sciaroidea).

The dipteran family Bolitophilidae, with the single extant genus Bolitophila, is a small family of mycophagous flies. In marked contrast to related families such as Sciaridae and Mycetophilidae, the family has a poor fossil record with no definite species assigned to the genus. In addition, the position of the extinct Cretaceous subfamily Mangasinae Kovalev, 1986 (described in Bolitophillidae) has been controversial and it has been suggested that species in this clade may belong to other sciaroid families. This situation is made worse by misplacement of the type specimen. We herein describe two new species of Bolitophila, Bolitophila warreni sp. nov. from the 46-million-year-old Kishenehn Formation in Montana, USA and Bolitophila rohdendorfi sp. nov. from Baltic amber. Bolitophila pulveris Lewis, 1969 is reassigned to Sciaroidea incertae sedis. The subfamily Mangasinae is reviewed and its position within the Bolitophilidae confirmed. Two new species of Mangas, M. kovalevi sp. nov. and M. brevisubcosta sp. nov., both from the Lower Cretaceous of Khasurty in Western Transbaikalia, are described.

First record of the family Bolitophilidae (Diptera: Sciaroidea) from the Lagunas de Zempoala National Park, Mexico, with description a new species.

The first record of the family Bolitophilidae from Mexico is reported from the "Lagunas de Zempoala" Natural Reserve, situated between the borders of the states of Morelos and Mexico (included in the Nearctic Region), with a description and illustration of a new species, Bolitophila (Bolitophila) zempoala spec. nov., based on adults males collected with Malaise traps at an altitude of 2,841 m. a. s. l. in the Neo-Volcanic Axis mountains. The new species from Mexico is very closely related to Bolitophila (Bolitophila) dubiosa Van Duzee, 1928 and B. (B.) dupla Garrett, 1925.