Bioacoustics of Stygopholcus photophilus

Redescription Male ( Crete ; ZFMK (Ar 22205)) MEASUREMENTS. Total body length 4.3, carapace width 1.5. Distance PME–PME 130 µm ; diameter PME 120 × 140 µm ; distance PME–ALE 30 µm ; diameter AME 60 µm ; distance AME-AME 30 µm . Leg 1: 40.4 (10.7 + 0.7 + 10.5 + 16.0 + 2.5), tibia 2: 6.9, tibia 3: 5.1, tibia 4: 5.7; tibia 1 L/d: 75. COLOR (in ethanol). Carapace pale whitish to ochre-yellow, ocular area and clypeus slightly darker (light brown), ocular area posteriorly with darker brown V-mark; sternum very dark brown, almost black; legs ochre yellow, with darker (light brown) rings on femora (subdistally) and tibiae (proximally and subdistally), with short dark longitudinal lines dorsally on femora ( Figs 127–128 ); abdomen ochregray, with distinct dorsal pattern consisting of brown band around heart and dorsal and lateral marks in posterior half; with white internal marks; ventrally with wide dark brown band, interrupted at two thirds between gonopore and spinnerets. BODY. Habitus as in Fig. 4 . 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 with very indistinct modified area medially (arrow in Fig. 129 ) and sclerotized margin. Sternum wider than long (1.05/0.70), unmodified. Abdomen oval to short cylindrical. CHELICERAE. As in Figs 119–120 , with pair of frontal apophyses set with 2 and 3 modified hairs, respectively, with 23 modified hairs each on frontal face ( Figs 130, 132 ); with strongly sculptured median margins ( Fig. 131 ); with stridulatory ridges ( Fig. 133 ). PALPS. As in Figs 9–11 ; coxa with prominent retrolateral hump; trochanter barely modified; femur with distinct retrolateral process proximally, with stridulatory pick (modified hair) proximally on prolateral side, with transversal dark line retrolaterally, distally strongly widened and with rounded ventral protrusion; femur-patella joints shifted towards prolateral; tibia very large, thickest at two thirds, with two trichobothria; tibia-tarsus joints shifted towards retrolateral; procursus dorsally with ~5 weakly curved hairs, with strong hump on prolateral side. Procursus tip ( Figs 113–114 , 137–138 ) with scoop-shaped dorsal sclerite, strong hinged ventral sclerite (triangular in ventral view), and complex membranous central part with brush of hair-like processes on retrolateral side. Genital bulb ( Figs 115–118 ) with basal sclerite connecting to tarsus, small dorsal process weakly sclerotized, and main sclerite consisting of retrolateral process and dorsal process; retrolateral process distally widening, distal margin with pair of heavily sclerotized bulges on ventral side; dorsal process with single slightly curved tip, proximally with two small apophyses. LEGS. With ~12 short spines in one row ventrally on femur 1; without curved hairs; few vertical hairs; retrolateral trichobothrium of tibia 1 at 2%; prolateral trichobothrium absent on tibia 1, present on other tibiae; tarsus 1 with irregular platelets rather than with distinct pseudosegments. Male (variation) Color pattern consistent but individual elements slightly variable in size and distinctness; median section of ventral abdominal band sometimes divided into three parallel longitudinal bands; dark abdominal marks sometimes divided into many small round dots. Tibia 1 (N = 104): 9.7–15.3 (mean 12.7); tibia 2 (N = 41): 6.5–10.4 (mean 8.4); spines on femur 1 (N = 11): 0–34 (mean 19); modified hairs on cheliceral basis (N = 50): 19–44 (mean 30); modified hairs on cheliceral apophysis (N = 50): 3–4 (mean 3.3); chelicerae maximum width (N = 35): 0.60–0.81 (mean 0.70); procursus length (N = 35): 1.22–1.50 (mean 1.36). Female In general similar tomale ( Fig. 5 ), but femur 1 without spines, clypeus unmodified. Without modifications posteriorly on carapace and anteriorly on abdomen. Tibia 1 (N = 91): 8.9–13.7 (mean 11.2); tibia 2 (N = 46): 5.3–9.5 (mean 7.2); epigynum width (N = 25): 0.98–1.34 (mean 1.16); epigynum length (N = 25): 0.62–0.86 (mean 0.72); epigynal measure F (N = 25): 0.22–0.38 (mean 0.29). Epigynum anterior plate roughly triangular, weakly protruding, with very strong transversal ridges in anterior part ( Fig. 144 ); with internal structures visible in uncleared specimens: oval to drop-shaped anterior structure, short parallel (anteriorly slightly converging) sclerites posteriorly; posterior plate short but wide. Internal genitalia (Figs 121–122, 151–152) with distinctive ventral arc ( Fig. 156 ; with several transversal, crescent-shaped sclerites and slightly elongate ventral pocket), with large pore plates (Fig. 122).

Diagnosis Easily distinguished from known congeners by many characters, including: distinct dark marks on entire abdomen ( Figs 4–5 ), also ventrally; dark rings on femora and tibiae, dark lines on femora ( Figs 127–128 ); male chelicerae with strongly sculptured median margins ( Figs 130–131 ); larger number of modified hairs on male cheliceral base ( Fig. 162 ; with little overlap); male palpal femur distally more strongly widened ( Fig. 11 ); palpal tibia widest in distal half ( Fig. 11 ); procursus distally with strongly projecting dorsal sclerite ( Figs 113–114 ); dorsal bulbal process not divided into two separate tips ( Figs 115, 118 ); spines on male femur 1 in single row; male tibia 1 much longer than tibia 2 (tibia 1/tibia 2> 1.40; in other species <1.40; Fig. 165 ); strong transversal ridges on anterior part of epigynum ( Fig. 144 ); relatively longer epigynum (epigynum width/length: usually <1.7, in other species usually> 1.7, with little overlap; Fig. 163 ); female without stridulatory ridges on chelicerae ( Fig. 134 ), and without stridulatory apparatus between prosoma and abdomen.