Nesticus holsingeri Gertsch, 1984

Hedin, Marshal & Milne, Marc A., 2023, New species in old mountains: integrative taxonomy reveals ten new species and extensive short-range endemism in Nesticus spiders (Araneae, Nesticidae) from the southern Appalachian Mountains, ZooKeys 1145, pp. 1-130 : 1

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).

Figures

Figure 13. Distribution of Nesticus tennesseensis group species. Type localities designated with yellow circles. State boundaries and major cities shown for geographic context. Dashed lines circumscribe known species distributions.

Figure 18. Nesticus holsingeri. Virginia, Scott Co., Pond Cave, MCH specimen # 1780, ♂ palp, ventral (A), dorsal (B) C Virginia, Washington Co., Brumley Creek, MCH 04 _ 026, ♂ palp, ventral. ♀ epigynum. Virginia, Washington Co., Brumley Creek, MCH 04 _ 026, epigynum, ventral (D), dorsal (E). Scale bar: 0.5 mm. ♂ habitus images F Virginia, Washington Co., Brumley Creek, MCH 04 _ 026 G Virginia, Scott Co., Pond Cave, MCH specimen # 1780. Scale bar: 1 mm.

Figure 19. Nesticus mimus ♂ palps. Virginia, Giles Co., Straley's Cave # 1, MCH specimen # 1396, dorsal (A), ventral (B) C Tennessee, Johnson Co., Backbone Rock Recreational Area, MCH 04 _ 025, ventral. Scale bar: 0.5 mm.

Figure 20. Nesticus mimus epigynal variation. Virginia, Giles Co., Straley's Cave # 1, MCH specimen # 1399, ventral (A), dorsal (B). Virginia, Washington Co., Neal's Sinks, MCH specimen # 1430, ventral (C), dorsal (D). Virginia, Smyth Co., near Hurricane CG, MCH 07 _ 087, ventral (E), dorsal (F). Tennessee, Johnson Co., Backbone Rock Recreational Area, MCH 04 _ 025, ventral (G), dorsal (H). Scale bar: 0.5 mm.