Revision of North American species of the subfamily Leptotyphlinae Fauvel, 1874
Goals: To conduct an extensive collecting program of the leptotyphline staphylinids in all areas of North America which have never been covered by the Wisconsin ice sheet or affected by the permafrost during the Quaternary glaciation. To revise the North American leptotyphlines, analyze their phylogeny and establish relations of North American leptotyphline genera to the lineages from other parts of the world, especially Western Palaearctic and Southern Temperate lineages. To analyze the biogeographical implications of leptotyphline phylogeny.
The subfamily Leptotyphlinae includes 45 genera and more than 500 species (Herman 2001; Gusarov 2003a, 2003b, 2003c). Leptotyphlines (see images) are tiny (about 1 mm long), blind, wingless and poorly pigmented soil-dwelling beetles which only rarely visit the upper layer of the soil (the leaf litter). Although leptotyphlines are known on all continents from arctic (continental Alaska) to equatorial areas (Congo) they are most common and diverse in temperate regions with Mediterranean type of climate (Mediterranean Western Palaearctic, California, Chile). The low dispersal ability of the leptotyphlines and the fact that they occur on all continents make them extremely valuable for biogeographical analysis.
Eleven genera and only 19 species (Herman 2001; Gusarov 2001, 2003a, 2003b, 2003c) of leptotyphlines have been described from the continental North America and Cuba (Coiffait 1959, 1962; Coiffait and Decou 1972; Sáiz 1975; Smetana 1986; Frank & Thomas 1984; Gusarov 2001, 2003a, 2003b, 2003c). They are known from Alaska (1 species), Idaho (1), California (12), Florida (1), Cuba (2), Belize (1) and Guatemala (1) (see Map 1 (North America) and Map 2 (California)). In June 2002 I collected five undescribed species of leptotyphlines in California (4 species) and Oregon (1 species representing undescribed genus). Additional undescribed species of Leptotyphlinae from Mexico, California, Oregon, Washington, Idaho and New Mexico have been found in collections (Newton et al. 2000; Navarrete-Heredia et al. 2002). For comparison, 153 species belonging to 11 genera are known from Italy alone (Pace 1996).
The low number of described North American species of leptotyphlines (when compared with well studied Western Palaearctic Region) suggests that in this region leptotyphlines represent a virtually unknown realm and it is very likely that hundreds of species of leptotyphlines occur in the United States alone.
As leptotyphlines do not have wings and never leave soil their ability to disperse must be very limited. Therefore it seems very likely that they did not survive the Quaternary glaciations in the areas affected by permafrost. At the same time the fact that a relict species of leptotyphlines occurs near Fairbanks, Alaska (Map 1), suggests that leptotyphlines should be capable of surviving cold winters and widely distributed across North America. The extreme rarity of the leptotyphlines in North American collections is due to the fact that no one used appropriate methods to collect them.
There seem to be two good methods to collect leptotyphlines. The most effective method is soil flotation as described by Coiffait (1959) and Pace (1996). While collecting in North America for my other projects I had an opportunity to use the flotation method in California and Texas. Almost every sample taken in California contained leptotyphlines and/or other strictly edaphic beetles (along with other soil arthropods). These preliminary results strongly suggest that in North America the leptotyphlines should be more widely distributed and more diverse than the ones currently known. Another method which occasionally produces good results is berlesing leaf litter, preferably after the litter has been sifted. This method seems to work only when the leaf litter is sufficiently wet. During dry periods leptotyphlines appear to migrate to deeper soil layers and do not appear in berlese extracts while soil flotation method still works.
As most North American species of leptotyphlines have been recorded only from their single type locality, it is unknown how wide the individual species range can be. My data on distribution of the two closely related undescribed species of Heterotyphlus from the Santa Lucia Mountains, California (Map 3) allow to estimate roughly the possible number of leptotyphline species in California. The two localities of Heterotyphlus sp. n. 1 are separated from the only known locality of Heterotyphlus sp. n. 2 by distances of 12 and 18 km. Extrapolation of these data gives an estimate of 70 species along the coastline of California and about 1300 species in the entire state.
It is not known how strongly the Nearctic leptotyphlines are restricted to particular habitats, for example, redwood forests, where some Californian species are found. The answers to these questions can be very important for biodiversity conservation programs. For example, a small isolated patch of redwood trees may be supporting a whole community of local endemic species which live in soil under the trees and may become extinct if the trees are cut.
California, with its twelve described species of Leptotyphlinae (Coiffait 1959, 1962; Sáiz 1975; Gusarov 2001), is the center of leptotyphline diversity in North America. The arid habitats of California act as effective barriers for these wingless soil beetles. This results in high level of local endemism in fragmented forested areas.
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Coiffait, H. (1962) Les Leptotyphlitae (Col. Staphylinidae) de Californie. Revue Française d'Entomologie, 29(2), 154-166.
Coiffait, H. & Decou, V. (1972) Recherches sur les Coléoptères hypogés de Cuba. I. Staphylinidae- Leptotyphlinae: Cubanotyphlus jimenezi n.g., n. sp. Revue d'Écologie et de Biologie du Sol, 9(1), 131-138.
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Gusarov, V.I. (2003a) Mayatyphlus carltoni Gusarov, a new genus and species of leptotyphline staphylinid beetle from Belize (Coleoptera: Staphylinidae: Leptotyphlinae). Zootaxa, 165, 1-7 [Accessible free of charge at <http://www.mapress.com/zootaxa/2003f/zt00165.pdf>].
Gusarov, V.I. (2003b) Cubanotyphlus guatemalae, a New Species of Leptotyphline Staphylinid from Guatemala (Insecta: Coleoptera: Staphylinidae). Studies on Neotropical Fauna and Environment, 38(2), 125-128.
Gusarov, V.I. (2003c) Idahotyphlus alleni Gusarov, gen. n., sp. n., a new leptotyphline staphylinid beetle from Idaho (Coleoptera: Staphylinidae: Leptotyphlinae). Zootaxa, 345, 1-8 [Accessible free of charge at <http://www.mapress.com/zootaxa/2003f/zt00345.pdf>].
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Pace, R. (1996) Coleoptera. Staphylinidae. Leptotyphlinae. Fauna d'Italia, 34. Bologna: Calderini, i-viii + 1-328.
Sáiz, F. (1975) Une nouvelle espèce de Leptotyphlinae de Californie (U.S.A.) (Coleopt. Staphylinidae). Nouvelle Revue d'Entomologie, 5, 43-45.
Smetana, A. (1986) Chionotyphlus alaskensis n. g., n. sp., a Tertiary relict from unglaciated interior Alaska (Coleoptera, Staphylinidae). Nouvelle Revue d'Entomologie (N. Sér.), 3(2), 171-187.
Last updated: April 16, 2009