Nesticus dykemanae, Hedin & Milne, 2023

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 dykemanae sp. nov.

Fig. 59A-I

Material examined.

Type material: Holotype: USA - Tennessee, Sevier Co. • ♂ holotype; Great Smoky Mountains NP, Hwy 441 near Chimney Tops trailhead; 35.6364°N, - 83.4709°W; 31 Jul. 2000; M. Hedin, J. Cokendolpher leg.; MCH 00_143 (SDSU_TAC000673); Type material: Paratypes: - Sevier Co. • ♂, 4♀; Great Smoky Mountains NP, Hwy 441 near Chimney Tops trailhead; 35.6364°N, - 83.4709°W; 31 Jul. 2000 ; M. Hedin, J. Cokendolpher leg.; MCH 00_143; Non type material: - Sevier Co. • ♂, 8♀; Great Smoky Mountains NP, Hwy 441 half way between tunnel and Chimney picnic area; 35.6414°N, - 83.4819°W; 16 Apr. 1994 ; M. Hedin, F. Coyle, B. Dellinger leg.; • 5♀; Great Smoky Mountains NP, Hwy 441 N Chimneys campground; 35.6406°N, - 83.4949°W; 27 Aug. 2005 ; M. Hedin, R. Keith, J. Starrett, S. Thomas leg.; MCH 05_098.

Diagnosis.

This species is included in a phylogenomic subclade with Nesticus jonesi and N. binfordae . Males share the double-tipped median apophysis with the latter species but differ in the shape of both distal and proximal tegular apophyses, lack a whip-like paracymbial paradistal process, and have a less modified ventral paracymbial process (Fig. 59A-C ). The epigynum is most distinctive in the larger phylogenomic subclade (including N. dellingeri ), with lateral bars that extend from the median septum obliquely upwards at approximately 45-degree angles, interrupting the lateral pockets (Fig. 59D-I ). Also, dark spermathecae lie below the septum bars, extending obliquely outwards.

Description of ♂ holotype

(SDSU_TAC000673). Carapace dusky cream to orange, with conspicuous faint dark pigment behind ocular area, and along carapace margin bleeding inwards. Legs approximately concolorous pale. Abdomen with strong paired, lateral darker markings on a dirty orange/gray background. All eyes approximately equal in size, except for AMEs, ~ 1/4 width of ALEs. Eyes with rings of dark pigment. CL 1.5, CW 1.3, abdomen length 1.5, total body length 3. Leg I total length 14.25 (3.95, 0.75, 4.35, 3.8, 1.4), leg formula 1423, leg I / CW ratio 11.0. Palp with broadly S-shaped tegular apophysis, distal part a particularly skinny curved blade with sharp tip, basal fork of apophysis a squat sclerotized spade with saw-like leading edge (Fig. 59A-C ). Median apophysis anvil-shaped, both ends with sharp tips, apical end more tongue-shaped. Conductor tip bent, surrounded by small funnel-shaped cuticular sheath. Paracymbium lacking paradistal process, distal process finger-like with slight serration along paradistal edge. Lacking a dorsomedial process. Distal part of ventral paracymbial process only slightly thickened, lobe-like (Fig. 59A-C ).

♂ Variation.

Other than the holotype male only two other males are known, and these closely match the holotype. MCH specimen #1977 (Fig. 59C ) appears slightly unusual because this male had recently molted.

Description of ♀ paratype

(SDSU_TAC000674). Carapace color as in male, dark pigment not as strong. Legs approximately concolorous pale, very faint pigmentation. Abdomen with strong paired, lateral darker markings on a slightly lighter background. Eye development as in male. Eyes with rings of dark pigment. CL 1.45, CW 1.25, abdomen length 1.95, total body length 3.4. Leg I total length 11.3 (3.25, 0.6, 3.35, 2.9, 1.2), leg formula 1423, leg I / CW ratio 9.0. Epigynum generally wider than tall, median septum with adjacent heart-shaped lateral pockets (considering both sides). Septum towards posterior end with lateral bars that extend obliquely upwards at approximately 45-degree angles, interrupting lateral pockets. Dark spermathecae lying below septum bars, extending obliquely outwards. Median septum broadening slightly past these bars and dipping inwards towards the abdomen. Viewed dorsally, dorsal internal plates lying distinctly above the sclerotized ring of the lateral pockets.

♀ Variation.

Females from adjacent locations share a very similar epigynal morphology (Fig. 59D-I ).

Distribution and natural history.

Known from three closely adjacent locations from near the headwaters of the West Prong of the Little Pigeon River, Great Smoky Mountains National Park, on the southwest slopes of Mt. Leconte (Fig. 53 ). All nearby surrounding collections have resulted in the collection of Nesticus reclusus (Fig. 53 ), suggesting that this microendemicity is real (rather than a collecting artifact). Gertsch (1984) also includes records of N. reclusus from the "top of Mt. Leconte".

1994 collections from near the Chimney Picnic Area resulting in collections of a male and eight females were from a "large talus breakdown in a south-facing cove" in rich hardwood forest.

Etymology.

Named to honor Wilma Dykeman (1920-2006), a writer, speaker, teacher, historian, and environmentalist who spent most of her life in western North Carolina and eastern Tennessee. Mrs. Dykeman was devoted to social justice and environmental integrity, discussing Appalachian water pollution in her classic 1955 book 'The French Broad’, and sharing a social justice award in 1957 for her co-authored book 'Neither Black Nor White’.

Remarks.

Part of a near phylogenomic trichotomy with Nesticus binfordae and N. jonesi (Figs 3 , 4 ), with sCF values near a lower limit.

This species was called " N novsp2 " (from site 49) in Hedin (1997b) and lumped with N. binfordae despite having distinctive (non-sister) ND1/16S sequences.

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 53. A distribution of Nesticus reclusus group species B distribution of Nesticus jonesi. Type localities designated with yellow circles. State boundaries and major cities shown for geographic context. Dashed lines circumscribe known species distributions. The geographic distribution of " N. cooperi - like " populations is circled; this includes some female-only locations which are inside this distribution and included here only for purposes of graphical convenience.

Figure 59. Nesticus dykemanae sp. nov. genitalia. ♂ palps - Tennessee, Sevier Co., Great Smoky Mountains NP, Hwy 441 near Chimney Tops trailhead, MCH 00 _ 143 (SDSU _ TAC 000673), ♂ palp ventral (A), dorsal (B) C Tennessee, Sevier Co., Great Smoky Mountains NP, Hwy 441, between tunnel and Chimney picnic area, MCH specimen # 1977, ♂ palp ventral. Scale bar: 0.5 mm. epigynal variation - Tennessee, Sevier Co., Great Smoky Mountains NP, Hwy 441 near Chimney Tops trailhead, MCH 00 _ 143 (SDSU _ TAC 000674), epigynum ventral (D), dorsal (E). Tennessee, Sevier Co., Great Smoky Mountains NP, Hwy 441, between tunnel and Chimney picnic area, MCH specimen # 1973, epigynum ventral (F), dorsal (G). Tennessee, Sevier Co., Great Smoky Mountains NP, Hwy 441, N of Chimneys campground, epigynum ventral (H), dorsal (I). Scale bar: 0.5 mm.