Nesticus carolinensis (Bishop, 1950)

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 carolinensis (Bishop, 1950)

Figs 24A-D , 25A-F , 26

Ivesia carolinensis Bishop, 1950: 9, pl. 2, figs 1-4.

Nesticus carolinensis : Gertsch 1984: 25, figs 68-70, 88-90; Holler et al. 2020: 230.

Nesticus mimus : Gertsch 1984: 26, figs 85-87 (in part); Holler et al. 2020: 230.

Material examined.

Type material: Holotype: USA - North Carolina, McDowell Co. • ♂ holotype; Linville Caverns , near Linville Falls ; 6 Apr. 1947, S.C. Bishop leg.; AMNH; Non type material: - Avery Co. • ♂; upper slopes of Mt. Grandfather ; 12 Oct. 1923; S.C. Bishop leg.; AMNH; • ♂, 6♀; Edgemont Road at Wilson Creek , 2 mi E Hwy 221; 36.0905°N, - 81.8026°W; 24 Aug. 2005; M. Hedin, R. Keith, J. Starrett, S. Thomas leg.; MCH 05_080; • 11♀, 8 imm; Edgemont Road, 1 mile below Hwy 221; 36.0859°N, - 81.815°W; 24 Aug. 2001; M. Hedin, M. Lowder leg.; MCH 01_163; • ♂, ♀, 3 imm; Elk River Cave , 1 mi S Elk River Falls; 36.1892°N, - 81.9617°W; 22 Aug. 2001; M. Hedin, M. Lowder leg.; MCH 01_155; • 2♀, 7 imm; Roseboro Road past first crossing of Rockhouse Creek ; 36.0192°N, - 81.7813°W; 24 Aug. 2001; M. Hedin, M. Lowder leg.; MCH 01_164; • 3♂, 9♀; W side of Grandfather Mtn., 1 mi. NE Linville on Hwy 221; 36.0825°N, - 81.8568°W; 16 Aug. 1992; M. Hedin leg.; - Burke Co. • ♀; Table Rock Mtn; 15 Jun. 1949, no collector information; AMNH; • 3♂, 4♀; Pine Gap Trail, W side of Linville Gorge, S of Linville Falls off Old NC 105; 35.9396°N, - 81.9219°W; 16 Aug. 1992; M. Hedin leg.; • ♂, 4♀, 12 imm; Pine Gap Trail, W side of Linville Gorge, S of Linville Falls off Old NC 105; 35.9396°N, - 81.9219°W; 25 Aug. 2001; M. Hedin, F. Coyle, M. Lowder, P. Paquin leg.; MCH 01_165; - Caldwell Co. • ♀, 1 imm; Burnt Field Branch Cave ; 9 May. 1995; C. Holler, C. Holler leg.; • 4♂, 4♀, 3 imm; China Creek at FR 4071 crossing, SW of Blowing Rock; 36.1151°N, - 81.6983°W; 24 Aug. 2001; M. Hedin, M. Lowder leg.; MCH 01_161; - McDowell Co. • 4♂, 10♀; Linville Caverns , S of Linville Falls, off Hwy 221N; 35.9189°N, - 81.9393°W; 16 Aug. 1992; M. Hedin leg.; • 2♂, 9♀, 5 imm; Hwy 221N, N of Linville Caverns; 35.9268°N, - 81.9385°W; 25 Aug. 2001; M. Hedin, F. Coyle, M. Lowder, P. Paquin leg.; MCH 01_166; • 2♀; off Hwy 221 N, N Linville Caverns ; 35.9317°N, - 81.9391°W; 24 Aug. 2005; M. Hedin, R. Keith, J. Starrett, S. Thomas leg.; MCH 05_081; - Watauga Co. • 7 imm (identification based on mitochondrial evidence); Green Mountain , Hwy 221, crossing of Green Mountain Creek; 36.1142°N, - 81.7782°W; 24 Aug. 2001; M. Hedin, M. Lowder leg.; MCH 01_162.

Diagnosis.

Males may be differentiated from other members of this species group by the combination of palps with a paracymbium with a wide, broad ventral process, the paradistal paracymbial process broad and triangular, a median apophysis that is a thin rectangle with an anterior sclerotized point, and a broad, singularly-pointed tegular apophysis that extends to ~ half the length of the median apophysis (Fig. 24A-D ). Females may be differentiated from other members of this species group by epigyna with lateral lobes that are approximately equal to or slightly longer than the median septum, anteriorly-elongated epigynal pockets, and (viewed dorsally) touching parallel medial margins that diverge posteriorly (Fig. 25A-F ).

Variation.

In males from different sample locations the distal tip of the tegular apophysis varies in shape from blunt (e.g., Grandfather Mtn, Edgemont Rd) to more fingerlike (e.g., N Linville Caverns, China Creek, Elk River Cave, etc.). This variation does not obviously follow geographic or phylogeographic (see below) lines. Females from different sample locations are relatively conservative in epigynal morphology (Fig. 25A-F ), except for the AMNH specimen from Table Rock Mountain (see further comments below).

Fig. 26 shows an example of variation in adult female body size for specimens from a single collection location (from Edgemont Road, MCH 01_163), illustrating why we have not considered body size variation as particularly taxonomically important in this revision.

Distribution and natural history.

Previously known only from caves, but quite common and abundant in suitable near-surface habitats. Mostly from the uplands between the Linville and Grandfather Mountains of western North Carolina, northeast of the Asheville Basin (Fig. 13 ).

Strong phylogeographic structuring is observed in the mitochondrial data, with a well-supported subclade found east of the Linville Gorge (China Creek, Green Mountain, Elk River Cave, Rockhouse Creek, etc.; Fig. 6 ). This phylogeographic break also corresponds to a small sampling gap (Fig. 13 ), so isolation by distance (with incomplete sampling) vs. isolation by geography (e.g., the Linville Gorge) cannot be distinguished.

Remarks.

Gertsch (1984) provisionally attributed specimens from two montane locations to Nesticus mimus : a single female from Table Rock Mountain (Burke County, NC), which he described and illustrated, and a male specimen from Grandfather Mountain. The Grandfather Mountain male matches N. carolinensis specimens from our collections, for which we also collected DNA data. The female from Table Rock Mountain has a divergent epigynal morphology from N. carolinensis (wider than tall, short spermathecae, etc. Fig. 25E, F ); we place the specimen here based mostly on geography, adjacent to our other Linville Gorge collections. It remains possible that the specimen is from north of Table Rock, closer to Watauga Lake (and locations for N. tennesseensis , see Fig. 22E, F ).

Holler et al. (2020) cite new cave records from McDowell County. They also attribute Burnt Field Branch Cave specimens (Caldwell County) to Nesticus mimus , but we have examined females from this location and consider them to be N. carolinensis , lacking the unique spermathecae of N. mimus .

This species is supported as sister to Nesticus paynei + N. roanensis with a 92% bootstrap and sCF value of 37.5 on the UCE concatenated maximum likelihood tree, and a lower local posterior probability value on the UCE ASTRAL species tree (Figs 3 , 4 ).

Figures

Figure 3. UCE concatenated maximum likelihood tree. Distant outgroups removed (for graphical purposes), specimen numbers correspond to those in Suppl. material 3 (with detailed location provided in Suppl. material 1). Node numbers correspond to bootstrap (bold text) / gCF / sCF. Only bootstrap values below 100 shown, all others 100. gCF and sCF values rounded to nearest integer; sCF values below 38 highlighted with red text.

Figure 4. UCE ASTRAL species tree. Distant outgroups removed (for graphical purposes), specimen numbers correspond to those in Suppl. material 3 (with detailed location provided in Suppl. material 1). Included are quartet support values (rounded to nearest integer), and local posterior probability values (if less than 1.0, red text). Branch lengths in coalescent units for internal branches only, terminal branch lengths arbitrary. Internal branch to Nesticus cressleri truncated for graphical purposes.

Figure 6. COI IQT gene tree. Distant outgroups trimmed. Specimen numbers correspond to those in Suppl. material 3 (with detailed location provided in Suppl. material 1). Sequences from UCE capture denoted with " NODE ". Populations with a " Nesticus cooperi - like " male paracymbium denoted by small circles. Not all tip bootstrap values shown (see Suppl. material 4 for. tre file with all bootstrap values).

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 22. Nesticus tennesseensis epigynal variation. Tennessee, Grainger Co., Indian Cave, MCH specimen # 1010, ventral (A), dorsal (B). North Carolina, Surry Co., near Fisher Peak, MCH specimen # N 1126, ventral (C), dorsal (D). Tennessee, Carter Co., near Watauga Lake, MCH 05 _ 078, ventral (E), dorsal (F). West Virginia, Raleigh Co., Grandview SP, MCH specimen # 1362, ventral (G).

Figure 24. Nesticus carolinensis ♂ palps. North Carolina, Avery Co., Elk River Cave, MCH 01 _ 155, dorsal (A), ventral (B). North Carolina, McDowell Co., Linville Caverns, MCH specimen # 1225, dorsal (C), ventral (D). Scale bar: 0.5 mm.

Figure 25. Nesticus carolinensis epigynal variation. North Carolina, McDowell Co., Linville Caverns, MCH specimen # 1227, ventral (A), dorsal (B). North Carolina, Avery Co., Elk River Cave, MCH 01 _ 155, ventral (C), dorsal (D). North Carolina, Burke Co., Table Rock Mtn. (AMNH specimen), ventral (E), dorsal (F). Scale bar: 0.5 mm.

Figure 26. Nesticus carolinensis habitus images, both adult females. North Carolina, Avery Co., Edgemont Road, MCH 01 _ 163. Scale bar: 1 mm.