Bioacoustics of Stygopholcus absoloni

Redescription Male (Zavala, MHNG) MEASUREMENTS. Total body length 5.8, carapace width 2.2. Distance PME–PME 150 µm ; diameter PME 140 × 180 µm ; distance PME–ALE 30 µm ; diameter AME 65 µm ; distance AME-AME 25 µm . Leg 1: 55.2 (14.8 + 1.1 + 14.0 + 22.1 + 3.2), tibia 2: 10.8, tibia 3: 8.7, tibia 4: 9.5; tibia 1 L/d: 62. COLOR (in ethanol). Carapace pale whitish to ochre-yellow, ocular area and clypeus slightly darker (light brown); sternum light brown, with darker brown radial marks; legs ochre yellow, without dark rings, without dark lines; abdomen monochromous pale gray, only above spinnerets with darker mark. BODY. Habitus as in Fig. 1 . Ocular area slightly raised. Carapace with deep median pit and pair of very shallow indistinct furrows diverging from pit to posterior margin of carapace. Clypeus unmodified. Sternum wider than long (1.50/1.00), unmodified. Abdomen oval, pointed at spinnerets. CHELICERAE. As in Figs 19–20 , with pair of large frontal apophyses set with 2 and 3 modified hairs, respectively, with 17 and 18 modified hairs each on frontal face; with distinct stridulatory ridges ( Fig. 35 ). PALPS. In general as in S. skotophilus (cf. Figs 6–8 ); coxa with retrolateral hump; trochanter barely modified; femur with distinct retrolateral process proximally, with stridulatory pick (modified hair) proximally on prolateral side; femur-patella joints shifted towards prolateral; tibia very large, with two trichobothria; tibia-tarsus joints shifted towards retrolateral; procursus ( Figs 12–13 ) slightly curved towards ventral, dorsally with curved hairs (distal third curved ‘upwards’), with strong hump on prolateral side (asterisk in Fig. 12 ). Procursus tip with evenly curved dorsal sclerite and strong hinged ventral sclerite (ds and vs in Figs 13 , 29 ); with strong conical process on prolateral side bordering hinged sclerite (arrow in Fig. 14 ); membranous central part on retrolateral side with brush of hair-like processes ( Fig. 29 ). Genital bulb ( Figs 15–18 ) with basal sclerite connecting to tarsus (bs in Fig. 15 ), small transparent dorsal process (arrow in Fig. 17 ; Fig. 33 ), and main sclerite consisting of long retrolateral process and short dorsal process (rp and dp in Figs 15–18 , 32 ); retrolateral process with bifid tip, distal part on ventral side thickened and heavily sclerotized; dorsal process with finger-shaped ventral tip slightly hooked, retrolateral tip wider, with additional strong protrusion on ventral side. LEGS. With short spines ventrally on femur 1 in two rows, prolateral row ~19 spines, retrolateral row ~24spines; withoutcurved hairs; few vertical hairs; retrolateral trichobothrium of tibia 1 at 3%; prolateral trichobothrium absent on tibia 1, present on other tibiae; tarsus 1 with irregular platelets rather than with distinct pseudosegments. Male (variation) Most males with monochromous abdomen with one or few dark marks above spinnerets; few males with additional dark marks laterally in posterior third. Tibia 1 (N = 60): 10.4–15.1 (mean 12.8); tibia 2 (N = 64): 7.6–11.5 (mean 9.6); spines on femur 1 (N = 27): 0–48 (mean 38); modified hairs on cheliceral basis (N = 122): 11–23 (mean 17.4); modified hairs on cheliceral apophysis (N = 122): 1–4 (mean 2.6); chelicerae maximum width (N = 61): 0.66–0.85 (mean 0.78); procursus length (N = 58): 1.10–1.28 (mean 1.21); bulbal measures A–E: A (N = 28): 0.31–0.37 (mean 0.35); B (N = 28): 0.06–0.08 (mean 0.07); C (N = 20): 0.22–0.28 (mean 0.26); D (N = 20): 0.18–0.23 (mean 0.21); E (N = 22): 0.68–0.77 (mean 0.73); epiandrous spigots (N = 20): 5–7 (mean 6.1). In the single male from Jama na Brezdanu ( Croatia ), the bulb differs in several respects from all other material examined, but it is unclear if this is teratological or not (even though it is symmetric). Most conspicuously, the heavy sclerite connecting the basal and distal bulbal sclerites (asterisk in Fig. 18 ) is much smaller and it is not connected to the basal bulbal sclerite; bulb measure Ealso deviates strongly (asterisk in Fig. 160 ). Female In general similar to male, but femur 1 without spines, with pair of indistinct processes posteriorly on carapace (arrows in Fig. 39 ) and pair of opposing poorly visible plates on abdomen; distance between processes/plates: 1.1. Tibia 1 (N = 55): 8.2–15.1 (mean 12.0); tibia 2 (N = 59): 4.4–11.1 (mean 8.6); epigynum width (N = 57): 0.72–1.22 (mean 1.05); epigynum length (N = 57): 0.42–0.68 (mean 0.54); epigynal measure F (N = 57): 0.21–0.37 (mean 0.30). Epigynum ( Figs 23–26 ) anterior plate semicircular, weakly protruding, with weak transversal furrows, with internal structures visible in uncleared specimens: round anterior structure and parallel sclerites posteriorly; posterior plate short but wide. Internal genitalia ( Figs 21–22 , 145–146 ) with distinctive ventral arc (va in Fig. 153 ; relatively shorter and wider than in other species), with large pore plates ( Fig. 22 ).