Bioacoustics of Cybaeolus

Description Small spiders (1.50–3.50) with eight eyes ( Fig. 15A ), anterior eye row slightly procurved in anterior view, posterior row slightly procurved to straight in dorsal view, AME normally developed, PME separated by one diameter of PME, clypeus no greater than 2.5× diameter of AME . Colour patterns of prosoma, and especially of opisthosoma, extremely polymorphic ( Figs. 21A , 22 , 23A , 24 , 25D , 26E , 27 ). Carapace light brown, with or without thoracic markings, without foveal furrow. Opisthosoma oval or elongate, it can be dark, pale, orange, or brown, mottled, with or without chevrons. Chelicerae with three or four promarginal and three retromarginal teeth, male with or without stridulatory file made of minute bumps, rastellum (a row of rake setae with thickened bases; Fig. 18C ) present in females of C. delfini and C. rastellus , absent in C. pusillus . Endites not convergent, serrula in a transverse line ( Fig. 18B ), posterior external margin variably inflated or projecting in males. Labium slightly wider than long, anterior edge straight, posterior slightly convex. Sternum shieldshaped, weakly concave anteriorly at base of labium. Male palp with simple retrolateral patellar apophysis with two or more distal thorns ( Fig. 15D ), RTA acute, curved, furrowed, tip with regular teeth pointing backwards ( Figs 15I–K ); a swollen area near the RTA base bears several thick setae. Cymbium oval, with retrolateral furrow leading to RTA ( Fig. 17J ). Copulatory bulb with disc-shaped tegulum, with a membranous patch where the fleshy median apophysis arises in C. delfini and C. rastellus ; only the membranous patch present in C. pusillus . Embolus arising proximally from tegulum, rotating clockwise (left palp, ventral view). Epigyne with paired copulatory openings, usually blocked with mating plugs ( Figs 17H , 18G ). Copulatory ducts long, leading to spherical spermathecae, fertilization ducts short, on posterior margin; accessory bulb unremarkable, restricted to small bump with gland ducts near the copulatory opening (observed only in C. rastellus ; Fig.18I ). Spinnerets ( Figs 3–6 ) in relatively compact group, PLS 70–80° from ALS , PMS 40–50° from ALS . ALS conical with wide base, PLS and PMS cylindrical, PLS equal in length to ALS , distal segment of ALS very short; distal segment of PLS very short, PLS not extended, length equal to or smaller than ALS . Colulus as two patches of setae. Spigot morphology (examined with SEM in adults of C. pusillus and C. rastellus ): ALS with one major ampullate gland spigot flanked by a nubbin, and 10–18 piriform gland spigots. PMS with one minor ampullate gland spigot, two cylindrical gland spigots in female, from five to eight aciniform gland spigots. PLS with one cylindrical gland spigot in female, from six to 11 aciniform gland spigots. Tracheal spiracle wide, slightly separated from spinnerets, leading to two thick trunks, each ramifying in three bundles of tracheoles, all limited to opisthosoma (observed from dissection of C. rastellus ; Fig. 18E ). Leg formula 1243. Spination: femora I with dorsal and prolateral spines, patellae with two dorsal spines, tibiae I and II with dorsal and prolateral spines, tibiae II and IV with dorsal, prolateral, ventral, and retrolateral spines, metatarsi III and IV with prolateral, retrolateral, and ventral spines. Trichobothria with longitudinal fingerprint striae on proximal plate ( Fig. 17F ), arranged on tarsi d0-1-0 or d0-1- 1-0 ( Figs 17D , 18D ), metatarsi d0-1-0 and tibiae d0-1-0. Tarsal organ a simple keyhole ( Fig. 17G ).