The genus Camptochaeta in Nearctic caves, with the description of C. prolixa sp. n. (Diptera, Sciaridae)

Abstract Camptochaeta prolixa sp. n. (Diptera, Sciaridae) is described from caves in Nevada, and three other congeneric species are recorded from caves in Nevada and Arkansas, United States. The new species shows some indication to a subterranean mode of life, including long antenna and legs, and in some specimens, reduction of the eye bridge.

Regarding the Nearctic Sciaridae, only specimens of 'Corynoptera sp.' have been recorded from a cave in Arkansas (Graening et al. 2003).
Between May 2006 and July 2007, a bioinventory of caves at Great Basin National Park, White Pine County, Nevada was undertaken, and that study has already led to the description of several new species, including two millipeds (Shear 2007, Shear et al. 2009), a springtail (Zeppilini et al. 2009) and an amphipod (Taylor and Holsinger 2011), with additional material still undescribed.

Material and methods
Though a variety of sampling methods have been implemented in the Great Basin cave bioinventory, sciarids of the genus Camptochaeta were only obtained by hand collections, often using an aspirator. The sampling effort included entrance, twilight and dark zone sampling in 21 caves over 64 visits, and most collections are associated with data on light, temperature, and relative humidity, all collected with handheld meters, as well as data on subtrate, cave zone and elevation. Samples were preserved in the field in 70% ethanol, and later sorted and curated in the laboratory, with select material being distributed to appropriate taxonomic experts.
Female. Slightly larger than male, wing length 3.0 mm, without diagnostic characters. Discussion. Camptochaeta prolixa isvery similar to C. subcamptochaeta found in central European caves, and the very similar C. pentacantha found in the Altay, Russia. C. prolixa differs from both by having a more slender gonostylus and by having the antennal flagellomeres longer, in most specimens more than five times as long as wide, with longer setosity; and by having a narrower eye bridge. C. prolixa and resembles the European cave-dwelling C. ofenkaulis by having long antenna and legs, but the gonostylus is remarkably different. Some specimens of C. prolixa show a tendency to a reduced eye bridge, which in addition to the long legs and antenna may be an accommodation to the subterranean mode of life.
Ten of the 11 specimens of C. prolixa were collected in the dark zones of caves, and one in the twilight zone. Based on microhabitat-specific data for ten specimens: air temperature ranged from 6.6 to 13.0 C, average 10.9 C; relative humidity ranged from 82.6 to 92.4 %, average 87.7 %; light ranged from 0 to <1 lux, average 0.0 lux; and elevation ranged from 2089 to 2013 m, average 2228 m. All C. prolixa specimens were collected in May (9 specimens) and July (2 specimens), even though sampling was carried out monthly in Lehman Caves. Most specimens were associated with bedrock or calcite walls or ceilings.
Etymology. The name is Latin (adjective), prolixa, streched out, referring to the very long extremities of the fly.
Camptochaeta mutua was described from Ithaca, New York (Johannsen 1912) and is recorded from eastern USA and Canada (Newfoundland, Ontario, Quebec and also from Yukon (Hippa and Vilkamaa 1994). Two specimens of C. pellax were collected from the dark zone of caves, with the following microhabitat-specific data: air temperature ranged from 10.9 to 13.0 C, average 11.95 C; relative humidity ranged from 84.4 to 88.6 %, average 86.5 %; light 0 lux; elevation ranged from 2089 to 2235 m, average 2162 m. Camptochaeta pellax is earlier known only from the type material from Colorado (Hippa and Vilkamaa 1994). The Nevada specimen of C. spicigera was collected in the entrance zone of a mine on wet rocks above water on the mine floor, with the following microhabitat-specific data: air temperature 9.7 C; relative humidity 52.5%; light 1755 lux; elevation 2621 m. Camptochaeta spicigera is earlier known only from the type material from Colorado (Hippa and Vilkamaa 1994).

Discussion
The distributions of temperature and humidity data for the new species are consistent with the morphological evidence that this species is a troglobite. Only one specimen was found in the twilight zone, and with the exception of that specimen, the species was always associated with elevated relative humidity and stable temperatures consistent with deep-cave habitats.
Our description of a new Camptochaeta brings the number of recently described cave organisms from Great Basin National Park to five. The sampled caves span a range of 1724 to 3413 meters in elevation, crossing a variety of vegetation zones from to above timberline. Within the caves, there are a variety of microhabitats with varying levels of nutrient input and habitat stability. In addition, the Park is located in a relatively sparsely populated area, with few entomologists. A combination of these factors may account for the relatively high number of new species recently described from this area.