Bioacoustics of Ninetis subtilissima

Description (amendments, see Huber & van Harten 2001 ) Tibia 1 in 16 males from Oman : 0.52–0.60 (mean 0.57); in 20 females from Oman : 0.50–0.64 (mean 0.60). Male chelicerae with stridulatory files consisting of ~35 ridges each, distances between ridges 1.4 µm ( Fig. 10C ). Female chelicerae without stridulatory files ( Fig. 10D ). Male gonopore with four epiandrous spigots in two pairs ( Fig. 10E ). Sexually dimorphic short vertical hairs ( Fig. 12D ) on male tibia 1 only, apparently in four rows, with ~4–14 hairs in each row. Thin metatarsal hairs present in female (one each on metatarsi 3 and 4; Fig. 12A, B ), not seen in male. Tarsal organ of leg 4 apparently non-functional. Other SEM characters as in congeners (leg cuticular plates and pores; other tarsal organs; trichobothria; chemosensory hairs; tarsal claws; spinnerets; Figs 10–12 ). Intraspecific distances. The genetic (K2P) distance between two sequenced specimens (from Wadi Tiwi and Wadi Ghul; geographic distance: 220 km ) was 11%; no morphological differences were seen between specimens of these localities.

NOTES: In contrast to the two known congeners ( N. minuta (Berland) and N. namibiae Huber ), but in agreement with most other ninetines, N. subtilissima has stridulatory ridges on the male chelicerae. However, the striation is extremely fine and difficult to see in light microscopy, and scanning electron micrographs of chelicerae of the other two species have not been made. The figures herein differ in some respects from Simon’s ( 1893 ) figures of the males and from Huber’s (2000) figures of the epigynum. Most notably, the long bulbal apophysis is strongly curved in Simon’s fig. 488, while it is almost straight in the new material. Also, the male cheliceral apophyses seem more slender in Simon’s fig. 489. In general, however, Simon’s illustrations are not reliable tools for species identification. The differences between the epigyna of the females from Ja’ar and the female syntypes are minimal and within the usual range of intraspecific variation. Therefore, we provisionally interpret the differences as resulting from either misdrawing or intraspecific variation, or from both.

MALE (Ja’ar): Total length 0.9; carapace width 0.45. Leg 1: 2.28 (0.61 + 0.16 + 0.57 + 0.60 + 0.33), tibia 2: 0.47, tibia 3: 0.37, tibia 4: 0.67; tibia 1 l/d: 9.5. Habitus as in figs. 1 and 2 (see also drawings of the very similar N. minuta in Huber, 2000 : figs. 315– 318). Prosoma and legs ochre yellow; opisthosoma gray, with white mark above spinnerets and very indistinct darker spots dorsally. Carapace without thoracic furrow (cf. female: fig. 9). Eye pattern as in female (cf. fig. 9); diameter (in µm; ± 3 µm) AME 30, ALE 65, PME 50, PLE 60; distance PME­PME 50, PME­ALE 30. Chelicerae as in figures 5 and 6, with pair of apophyses frontally and very fine stridulatory ridges laterally (fig. 11); cheliceral laminae as in female (cf. fig. 10); cheliceral glands open through pores at slightly modified fields close to tips of fangs (figs. 12, 13). Sternum with small humps near bases of coxae 1. Palps as figures 3 and 4, with simple procursus that is pointed distally, and genital bulb with two processes: embolus dorsally and pointed (slightly hooked) apophysis ventrally; palpal tarsal organ capsulate with small orifice (fig. 15). Legs without spines, without curved hairs, with very few short vertical hairs; ‘‘normal’’ mechanoreceptive hairs of variable shape (e.g., figs. 24, 25); three trichobothria on tibiae, one on metatarsi; trichobothria with simple capsulate basis (fig. 27); retrolateral trichobothrium on tibia 1 at 58%; tarsus 1 apparently with 5 pseudosegments, barely visible as slightly darker rings in light microscope, but not discernible in SEM (figs. 25, 26). Three tarsal claws: superior claws with about 12 teeth, inferior claw with two teeth (fig. 28). Opisthosoma globular, with long hair dorsally. Three pairs of spinnerets, colulus possibly represented by modified area between ALS (fig. 19); ALS with one widened, one pointed, and several cylindrically shaped spigots (figs. 16, 17); PMS with one pair of cylindrically shaped spigots (fig. 18); PLS without spigots. Anal tubercle with multibranched hairs (fig. 22). FEMALE (Ja’ar): In general very similar to male. Carapace width 0.48; tibia 1: 0.60. Palpal tarsal organ as in figure 14. Tip of palp with strong spine (fig. 20). Epigynum consisting of posterior plate and large frontal plate with median pocket opening posteriorly (figs. 7, 21 , 23 ); dorsal view as in figure 8. See Huber ( 2000 ) for redescription of female syntypes.