Nesticus furtivus Gertsch

Hedin, Marshal & DELLINGER, Bob, 2005, Descriptions of a new species and previously unknown males of Nesticus (Araneae: Nesticidae) from caves in Eastern North America, with comments on species rarity, Zootaxa 904, pp. 1-19 : 12-14

Nesticus furtivus Gertsch 1984

Figs. 1, 15-16

Nesticus furtivus Gertsch1984: 27, figs. 97-99.

Material Examined: Holotype. - Female, U.S.A: Tennessee: Hamilton County, Crystal Caverns (= Raccoon Mountain Caverns), Black Creek Valley, Raccoon Mountains, coll. 14 April 1938, J.M. Valentine (housed at AMNH).

Additional Type Locality Material Examined. - Female, U.S.A: Tennessee: Hamilton County, Raccoon Mountain Caverns, 35°01 ’27” N, 85°24 ’47” W, elev. ~ 260 meters, coll. 28 March 1993, M. Hedin & M. Wolinsky ( MCH female specimen # 1660); Male, data as for female, coll. 25-26 July 2000, M. Hedin, D. Wood, B. Delllinger, S. Perlaky, P. Perlaky, & C. Varnell ( MCH 00_137 male specimen #1).

Remarks. - Previously known only from the holotype female, collected in 1938 from Crystal Caverns (= Raccoon Mountain Caverns), Black Creek Valley, Raccoon Mountains, Hamilton County, Tennessee.

Diagnosis. - The troglomorphic features of N. furtivus readily distinguish this species from smaller, surface-dwelling Nesticus found further east and north in the Appalachians. As compared to other Appalachian troglomorphs, the male palpus of this species is most similar to that of N. barri Gertsch (1984: figs 121-123; Figs 9 & 10). In particular, the distal and ventral paracymbium is essentially unmodified, and the dorsal paracymbium includes a simple, thin process (compare Figs. 9, 10 & 16). However, the tip of this process is modified and twisted in N. furtivus, but unmodified in N. barri. In addition, the tegular apophysis is laterally flattened and closely follows the median apophysis in N. furtivus , unlike the condition seen in N. barri. As suggested by Gertsch (1984), the tubercle at the posterior margin of the median septum of the epigynum is diagnostic for N. furtivus.

Description of male from type locality ( MCH 00_ 137 male specimen #1) (Figs. 15 & 16; Table 1). -Color of appendages and carapace almost uniformly pale tan to orange, approximating HTML color "dark orange #FF8C00". Abdomen slightly paler, without markings. Secondary eyes visible only as minute white patches of cuticle. No external evidence for principal eyes. Leg formula 1423. Leg I about 9 times longer than carapace width. Palp with an approximately translucent, elongate dorsal paracymbial process that parallels cymbium, with a thin distal projection. Distal end of paracymbium without processes. Ventral paracymbium with translucent basal flange. Tegular process compressed laterally, wrapping closely around median apophysis, shape approximating a sickle blade.

Redescription of female from type locality ( MCH female specimen #1660) (Table 1). - Gertsch (1984) describes the holotype female as with "cephalothorax and appendages whitish, without pattern; abdomen grey. Eyes obsolete." The legs of the holotype female are relatively long (e.g., leg IV is 9.85 mm). The redescribed female is mostly consistent with this description. Color of carapace and legs similar to male, unpatterned abdomen lighter and more creamy in coloration. Secondary eyes visible only as minute pearl-colored patches of cuticle. No external evidence for principal eyes. Leg formula 1423. Leg I over 10 times longer than carapace width. Epigynum as described by Gertsch (1984: fig 97), with "medium septum produced at posterior end into narrowly rounded projection ".

Natural History. - Both male and female described specimens were collected deep in the cave, beyond the commercial section in the vicinity of the "Skylight Dome". Skylight Dome is a high-humidity room, with considerable litter accumulation on the floors, washed in with surface flooding. Spiders were found fairly high in the room, occupying webs spanning small (15-30 cm) vertical spaces. Additional specimens (not collected) have been observed over a 10-year time period in other locations deep within this cave (see Discussion).

Distribution. - Known only from the type locality in southeastern Tennessee, near the junction of the Tennessee, Alabama, and Georgia borders (the “TAG” region). This location is a commercial cave that has had multiple prior names, including "Tennessee Caverns", "Crystal City Caverns", and "Crystal Caverns", and is now called "Raccoon Mountain Caverns". The cave is formed in limestone exposures at the eastern edge of the Cumberland Plateau (Fig. 1).

DNA sequences. - Mitochondrial 16S (accession number AF 004621) and nuclear ITS ( AF 003791) DNA sequences were reported in Hedin (1997a).