Bioacoustics of Crossopriza lyoni

Redescription Male ( Guinea , ZFMK Ar 10456) MEASUREMENTS. Total length 6.5, carapace width 2.4. Distance PME–PME 140 µm; diameter PME 140 × 170 µm; distance PME–ALE 50 µm; diameter AME 130 µm; distance AME–AME 45 µm. Leg 1: 63.4 (18.7 + 0.9 + 17.6 + 22.7 + 3.5), tibia 2: 12.4, tibia 3: 9.2, tibia 4: 10.5; tibia 1 L/d: 70; femora 1–4 diameters: 0.36, 0.32, 0.28, 0.31. COLOR (in ethanol). Carapace ochre-yellow; carapace pit anteriorly light brown; sternum dark brown; legs ochre-yellow, with indistinct darker rings subdistally on femora and tibiae, with black lines on femora and tibiae, patellae brown; abdomen ochre-gray, with whitish internal marks and some dark marks dorsally and laterally; ventrally with distinct black median band, partly disrupted, with three parallel longitudinal marks behind gonopore. BODY. Habitus as in Figs 702–703 . Ocular area slightly raised. Deep thoracic pit and pair of furrows diverging from pit toward posterior margin. Clypeus unmodified, rim barely more sclerotized than in female. Sternum wider than long (1.7/1.0), unmodified. Abdomen slightly elongated, dorso-posteriorly angular. CHELICERAE. As in Figs 792–793 , with two pairs of apophyses, lateral pair with 2–3 small processes (distinct in lateral view), median pair with one large modified cone-shaped hair each; distance between tips of modified hairs 80 µm; lateral stridulatory ridges fine but visible in dissecting microscope; distances between ridges: ~7.5 µm ( Huber et al. 1999 ). PALPS. As in Figs 783–785 ; coxa with rounded retrolateral hump; trochanter barely modified; femur distally widened, with rounded ventral protrusion, proximally with prolateral stridulatory pick, retrolateral-ventral rim with row of projecting and sclerotized hair-bases, with barely visible retrolateral transversal line, without retrolateral proximal process; femur-patella joints slightly shifted toward prolateral side; tibia large relative to femur, tibia-tarsus joints shifted toward retrolateral side; tarsus without macrotrichia; procursus ( Figs 786–788 ) straight, densely set with long hairs dorsally, few hairs slightly curved upwards; proximally on prolateral side with strong hump set with numerous long hairs and followed distally by thick sclerotized ridge, procursus tip with several distinctive elements: ventral sclerite with transparent retrolateral branch (arrow in Fig. 788 ), rounded dorsal sclerite, semitransparent prolateral pointed process, and pair of crescent-shaped retrolateral elements; genital bulb ( Figs 789–791 ) with simple basal sclerite connected to distal (main) sclerite, sperm duct opening not seen; distal sclerite with retrolateral ridge and distinctive set of one large and four smaller rounded prolateral apophyses. LEGS. Femur 1 with single row of ~23 ventral spines; without curved hairs; few vertical hairs; retrolateral trichobothrium of tibia 1 at 4%; prolateral trichobothrium absent on tibia 1, present on other leg tibiae; tarsal pseudosegments indistinct except 2–3 distally. Male (variation) Tibia 1 in 43 males : 11.5–18.0 (mean 14.5). Dark ventral band on abdomen variably distinct, section behind gonopore with 2–4 longitudinal bands. Small apophyses prolaterally on bulbal sclerite variably distinct, usually one large plus four small apophyses, rarely one large plus three or five small apophyses. Retrolateral branch on ventral sclerite of procursus slightly variable in shape. Female In general similar to male ( Figs 704–705 ) but without spines on legs, with smaller and less distinct stridulatory files on chelicerae (sometimes not visible in dissecting microscope; distances between ridges: ~8.5 µm, Huber et al. 1999 ), and with stridulatory organ consisting of pair of weakly sclerotized but distinct processes posteriorly on carapace and pair of light brown plates anteriorly on abdomen ( Fig. 797 ). Tibia 1 in 57 females : 9.2–15.5 (mean 12.5). Epigynum as in Figs 796–799 , main epigynal plate short and wide, weakly protruding; posteriorly laterally strongly sclerotized, anteriorly weakly sclerotized, with variably distinct light brown median area; with pair of pockets very close to median line on both sides of median ridge (distance between pockets 30 µm), posteriorly barely protruding; internal sclerotized arc and median round structure visible in uncleared specimens; posterior plate short but wide. Internal genitalia ( Figs 794–795 , 800–802 ) with large elongate pore plates converging anteriorly, dorsal arc wide but simple, ventral arc medially slightly modified, with asymmetric sclerites ( three females cleared), with simple median pouch. Gynandromorphic specimen Specimens that combine male and female morphological characters (sometimes in a left-right asymmetry) are extremely rare in pholcid spiders. The only previously known case was reported by Blackwall (1867) , who described a specimen of C. lyoni from India that had a male left palp and a male left chelicera, but a female right palp, female right chelicera, and incompletely developed female genitalia (epigynum) on the right side. He noted that this was the only case of gynandromorphism among “many thousands” of specimens of spiders studied. Surprisingly, the only gynandromorphic pholcid specimen I have ever seen (among roughtly 50,000 specimens) is also a representative of C. lyoni . This specimen (from Chuuk Island, Micronesia ), has a half epigynum ( Figs 804–805 ; relatively normally developed on the left side), but an enlarged right palp that reminds of a penultimate instar male palp (arrow in Fig. 803 ). The right chelicera and the right femur are not modified, as would be expected from a penultimate instar male. Surprisingly, however, the female stridulatory apparatus between prosoma and abdomen appears fully and symmetrically developed on both sides (arrows in Fig. 805 ). Leg length is also symmetric.