Nesticus jemisinae, 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 jemisinae sp. nov.

Fig. 9A-D

Material examined.

Type material: Holotype: USA - Tennessee, Marion Co. • ♂ holotype; Rainbow Cave (TMN20); 20 Oct. 2021; K.S. Zigler leg.; SDSU_TAC000662 ; Paratypes: • ♀ paratype; data as for holotype; SDSU_TAC000663 ; • ♂, 2♀ paratypes; data as for holotype; SDSU_TAC000664; Non type material: - Marion Co. • ♀; Rainbow Cave (TMN20); 10 Nov. 2013; K.S. Zigler leg. ; KSZ 14-248. • 5 imm; Rainbow Cave (TMN20); 20 Oct. 2021; K.S. Zigler leg.

Diagnosis.

Easily distinguished from other members of the Nesticus archeri group. Distinctly small-bodied Nesticus jemisinae possesses well-developed eyes, different from the eyeless N. cressleri and N. stygius . Males possess a relatively simple paracymbium, contrasting with the multiple apophyses of the complex paracymbium of N. archeri (Fig. 10A ) and N. pecki ( Hedin and Dellinger 2005: figs 17, 18). The distinctive tegular apophysis is dark and sinuous, extending under the median apophysis. Female N. jemisinae may also be distinguished from the latter species by the epigynum. The epigynum of N. archeri is subtriangular with large anterior fovea and a narrow median septum (Fig. 10B, C ), N. pecki possesses a broad posteriorly-broadening median septum (Fig. 11A-C ), and N. jemisinae possesses a posteriorly-pointed median septum with the spermathecae expanded into small bulbs distally (Fig. 9C, D ).

Description of ♂ holotype

(SDSU_TAC000662; Fig. 9A, B ). Carapace and appendages are a dusky yellow. Abdomen mottled gray with darker patches between lighter parts. Eyes ringed with black and equally well-developed except for AME, which are significantly reduced. Carapace 1.18 long, 1.09 wide. Total body length 2.43. Leg I total length 9.50 (2.74, 0.46, 2.73, 2.56, 1.01), leg I / CW ratio 8.72, leg formula 1423. Paracymbium of palp relatively simple with a large proximally directed ventral process and a dark sinuous distal process. Dorsal process of paracymbium largely reduced to a shallow pocket on the distal edge. Palp tegular apophysis dark, long, narrow, pointed, and extends under median apophysis. Median apophysis elongated towards base of palp and angled proximally at tip.

♂ Variation.

No significant genitalic variation was noted in the material examined.

Description of ♀ paratype

(SDSU_TAC000663; Fig. 9C, D ). Color of carapace, appendages, and abdomen as in male. Eyes as in male. CL 1.20, CW 0.97. Total body length 2.61. Leg I total length 7.96 (2.30, 0.44, 2.29, 1.98, 0.95), Ieg I / CW ratio 8.21, leg formula 1423. Epigynum width approximately half the width of the abdomen. Median septum pointed posteriorly and flanked by fovea along posterior margin. Internal foveal pockets visible from ventral inspection without dissection extending anteriorly angled outwards. Thin, elongate spermathecae curve slightly on outside margins of epigynum, extending anteriorly beyond foveal pockets, expanded into small bulbs distally.

♀ Variation.

No significant genitalic variation was noted in the material examined.

Distribution and natural history.

Known only from Rainbow Cave, located near Pocket Creek, a tributary to the Little Sequatchie River (Fig. 8 ). This cave is approximately 200 meters in length; spiders were collected ~ 50 meters from the cave entrance on the cave ceiling and walls, in total darkness.

Etymology.

The specific name is a matronym in honor of N. K. Jemisin whose 'Broken Earth’ book series features a subterranean colony, including scientists who study caves.

Remarks.

Nesticus jemisinae sp. nov. is a relictual, single-site endemic whose morphology is quite distinct from that of other members of the species group. This species is nested within a diverged nuclear and mitochondrial subclade of the Nesticus archeri group, sister to N. pecki and N. archeri (Figs 3 , 4 , 6 ).

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 8. Distribution of the Nesticus archeri group, including Nesticus archeri, N. pecki, N. jemisinae, N. cressleri, and N. stygius. State boundaries and major cities shown for geographic context. Dashed lines circumscribe the distributions of N. pecki and N. stygius.

Figure 9. Nesticus jemisinae sp. nov. Tennessee, Marion Co., Rainbow Cave, ♂ holotype, SDSU _ TAC 000662, ventral (A), dorsal (B). Rainbow Cave, ♀ paratype, SDSU _ TAC 000663, ventral (C), dorsal (D). Scale bar: 0.5 mm.

Figure 10. Nesticus archeri A Alabama, Clay Co., vicinity Mill Shoal Creek, ♂ specimen MCH # 2132, ventral palp B Alabama, Clay Co., vicinity Mill Shoal Creek, ♀ specimen MCH # 2129, epigynum, ventral view C dorsal view. Scale bar: 0.5 mm.

Figure 11. Nesticus pecki epigynum variation, ventral views A Tennessee, Marion Co., Monteagle Saltpeter Cave, specimen # 1625 B Tennessee, Fentress Co., Hurricane Maze Cave, MLN 13 - 063 (SDSU _ G 2100) C Tennessee, White Co., Haskell Sims Cave, MLN 14 - 004 (SDSU _ G 3697). Scale bar: 0.5 mm.