Nesticus holsingeri Gertsch, 1984

Fig. 18A-G

Nesticus holsingeri Gertsch, 1984: 25, figs 66-67, 91-93.

Material examined.

Type material: Holotype: USA - Virginia, Scott Co. • ♂ holotype; Pond Cave; 5 Nov. 1966; J. Holsinger, S. Taylor leg; AMNH; New collections from type locality: USA - Scott Co. • 2♂, 7♀; Pond Cave, Rye Cove; 6 Oct. 1993; M. Hedin, C. Phillips leg; Non type material: - Russell Co. • ♂; Banners Corner Cave; 10 Apr. 2017; T. Malabad leg.; • ♂, 2♀; Bundys Cave No. 1, west of Lebanon, VA; 31 Jan. 2020; T. Malabad, R. Reynolds leg.; • ♂, ♀, 8 imm; Concrete Tank Cave; 24 Jul. 2017; T. Malabad leg.; • ♂, 3♀, 12 imm; Daugherty Cave, northeast of Lebanon, VA; 10 Apr. 2017; T. Malabad leg.; • 2♀; Daugherty Cave; 26 Jun. 2020; T. Malabad, A. Malabad leg.; • ♀; Ferrells Cave, northeast of Rosedale, VA; 26 Jun. 2020; T. Malabad, A. Malabad leg.; - Scott Co. • 4♂, 11♀; Alley Cave, E of Natural Tunnel SP; 19 Sep. 1992; M. Hedin, S. O’Kane leg.; • ♂; Alley Cave; 6 Oct. 1993; M. Hedin, C. Phillips leg.; • 3♂, ♀; Alley Cave; 22 Aug. 2005; M. Hedin, R. Keith, J. Starrett, S. Thomas leg.; MCH 05_072; • 2♀; Cox Ram Pump Cave; 3 Aug. 2016; T. Malabad leg.; - Washington Co. • 3♂, ♀; Brumley Creek, near Brumley Gap; 36.7933°N, - 82.0229°W; 7 Aug. 2004; M. Hedin, R. Keith, J. Starrett, S. Thomas leg.; MCH 04_026; - Wise Co. • 4♂, 6♀; Burton’s Cave, SW of St Paul; 8 Oct. 1993; M. Hedin, C. Phillips leg.

Diagnosis.

Strongly supported by both mitochondrial and UCE data as sister to Nesticus mimus . The male tegular apophysis of N. holsingeri is shorter (nearly as wide as long) with a more pronounced narrowing tip (Fig. 18A, C) than in N. mimus (Fig. 19B, C). Nesticus holsingeri epigyna are more squarish and lack conspicuous elongate spermathecae (Fig. 18D, E), as compared to longer (anterior to posterior) N. mimus epigyna with conspicuous elongate spermathecae (Fig. 20A-H).

Variation.

This species exhibits interesting variation in somatic morphology. Specimens from Pond Cave are pale and long-legged with reduced eye pigmentation, specimens from Burton’s Cave and Alley Cave are pale and long-legged but with well-developed eyes, and specimens from the surface Brumley Creek population exhibit an “epigean” habitus, with dark abdomens, shorter legs, and well-developed eyes (Fig. 18F, G). Minimal genitalic variation was observed across sample locations.

Distribution and natural history.

Known only from a small area in southwestern Virginia, in the upper Clinch River drainage basin (Fig. 13). All known records are from limestone caves, except for the Brumley Creek population where spiders were collected from under surface rocks in a moist, north-facing stream valley. This species has been collected in near syntopy with Nesticus carteri at Alley Cave, Virginia. At this site N. carteri is found under rocks in talus in a sink leading to the cave entrance, whereas N. holsingeri has only been collected from the dark zone of the cave.

Remarks.

The variation in degree of troglomorphy within this single species suggests that this character suite (eye development, pigmentation, leg length, etc.) can evolve relatively rapidly, as seen in other cave spider taxa (e.g., Arnedo et al. 2007).