Figures 1–22
Type material. Holotype ♂: MEXICO: San Luis Potosí: Ríoverde, Parque Nacional El Potosí, El Varal (21.89475°N, 100.34412°W, 1775 m a.s.l.), leaf litter, hand collecting, leg. E. Rodríguez, 2.IX.2017 (CARCIB-Ar-031).
Paratype: Same data as holotype, except Cañada Grande (21.92094°N, 100.32842°W, 1999 m a.s.l.), decaying trunk, 12.IV.2018, 1♀ (CARCIB-Ar-0214).
Etymology. The specific epithet is a noun in apposition taken from the type locality.
Diagnosis. The male of this species is quite distinct from those of all Mexican Scotinella by the long and filiform embolus, with an ovoid base, arising at the middle of the tegulum. Females are distinguished by the W-shaped copulatory ducts and contiguous copulatory ducts located anteriorly.
Description. Male holotype. Coloration: carapace dusky brown, with thin dark brown margins, and faint lines (Fig. 1). Chelicerae, endites and sternum light brown, labium dusky brown (Fig. 2). Leg segments brown, except coxae, which are light brown. Opisthosomal dorsum shiny brown, sides with black streaks, dorsal scutum as long as opisthosoma (Fig. 1); venter dusky light brown, margins with black streaks, epigastric area brown (Fig. 2). Total length 2.11. Carapace 1.02 long, 0.89 wide. Opisthosoma 1.09 long, 0.69 wide. Carapace oval, eye region narrow. Fovea longitudinal. AER straight as seen from above, procurved as seen from the front, PER straight as seen from above (Fig. 1). Eye diameters and interdistances: AME 0.08, ALE 0.08, PME 0.06, PLE 0.08, AME–AME 0.04, AME–ALE 0.02, PME–PME 0.04, ALE–PLE 0.04, MOA length 0.16, MOA front width 0.28, MOA back width 0.30. Sternum 0.66 long, 0.56 wide. Endites 0.26 long, 0.23 wide. Labium 0.13 long, 0.14 wide. Leg measurements: I 3.08 (0.86, 0.36, 0.78, 0.68, 0.40), II 2.70 (0.80, 0.36, 0.50, 0.62, 0.42), III 2.38 (0.60, 0.30, 0.48, 0.60, 0.40), IV 3.40 (0.84, 0.32, 0.82, 0.92, 0.50). Chelicerae with one macroseta. Macrosetae: palp: fe d0-0-1; leg I: fe p0-0-1, ti v6-4-2, mt v2-4-1p; leg II: ti v4-4-1p, mt v3-2-2; leg III and IV: mt with preening brush. Palp: Femur with broad shallow groove near apophysis (arrow in Figs 19–20), femoral apophysis hooked and nearer base of segment, setose distally (Figs 18, 20–21); RTA bifid, dRTA long, apex attenuated and slightly curved (Fig. 12–13), vRTA slightly longer than half of dRTA (Fig. 12); cymbium with several setae around embolus tip (Fig. 16); tegulum rounded retrolaterally (Fig. 13); embolus base expanded, ellipsoid; embolus very long, extending far beyond margin of cymbium, and very slender (Figs 12, 16); rugose conductor leaf-like in ventral view (Fig. 16); bulb deeply excavated retrolaterally at distal end (Figs 12, 16); portion of tegulum highly sclerotized, just behind conductor (arrow in Fig. 16).
Female paratype. Coloration: carapace as male, but lighter (Fig. 3). Opisthosomal dorsum greyish brown (Fig. 3), venter greyish brown, epigastric region light brown (Fig. 4). Total length 2.51. Carapace 1.12 long, 0.95 wide. Opisthosoma 1.45 long, 1.12 wide. Carapace, fovea, and eyes as male. Eye diameters and interdistances: AME 0.08, ALE 0.08, PME 0.06, PLE 0.08, AME–AME 0.04, AME–ALE 0.02, PME–PME 0.04, ALE–PLE 0.04, MOA length 0.18, MOA front width 0.32, MOA back width 0.34. Sternum 0.72 long, 0.62 wide. Endites 0.23 long, 0.16 wide. Labium 0.10 long, 0.10 wide. Leg measurements: I 3.38 (0.90, 0.42, 0.92, 0.70, 0.44), II 3.14 (0.88, 0.38, 0.70, 0.70, 0.48), III 2.72 (0.68, 0.36, 0.52, 0.72, 0.44), IV 4.18 (1.12, 0.44, 0.96, 1.06, 0.60). Chelicerae with two macrosetae, ectal smaller. Macrosetae: palp: fe d0-0-1, pa p1-0-0, ti d1-0-0, p1-0-0, ta with ventral patch of setae; leg I: fe p0-0-2, ti v6-4-2, mt v2-4-1p; leg II: ti v4-4-2, mt v3-2-2; leg III and IV: mt with preening brush. Epigyne: copulatory openings small, located on anterior epigynal margin, leading into longitudinal median copulatory ducts, which extend almost to posterior margin, then reverse direction, W-shaped, visible through integument (Figs 5, 8). Endogyne: spermathecae oval, posterolateral to copulatory openings (Figs 6–7, 9–10); small bursae arising anteriorly from junction between copulatory ducts and spermathecae; fertilization ducts arising mesally (Figs 7, 9–10).
Natural history. The male was found in the leaf litter of oak-pine forests, whereas the female was under a decaying log. Moreover, S. elpotosi sp. nov. shares the microhabitat with a Phonotimpus sp. at the type locality.
Distribution. This species is only known from the type locality, at National Park El Potosí, San Luis Potosí, Mexico. For the known distribution of all Mexican Scotinella species see Fig. 22.
Remarks. The female was not collected with the male but is matched based on geographic proximity, similarity in coloration and size, and congruent length of the embolus and copulatory ducts.