Chthonius leoi

Chthonius leoi (Callaini, 1988)

(Figs 309–311, 411)

Neochthonius leoi Callaini, 1988: 179, figs 2a–e.

Type locality: Italy, Sardinia, Oristano Province, Bauladu, Santa Vittoria [as San Vittore] (40°00’56”N, 8°40’24”E).

Distribution. Italy (Sardinia).

Diagnosis (♀). An epigean Chthonius that differs from other species of the ischnocheles group in the following combination of characters: anterior margin of carapace without preocular microsetae; posterior margin of carapace with 4 macrosetae; no eyes; chelicerae with 1 or 2 lateral microsetae; chela length 0.38–0.40 mm; movable chelal finger length 0.225 –0.265 mm; chelal fingers with contiguous teeth; both fixed and movable chelal fingers at level of est-ist and st-t with about 11 teeth occupying 0.05 mm; movable chelal finger with coupled sensilla pc on a noticeable tubercle.

Type material examined. ITALY — Sardinia: 1 ♀ (paratype), “ Sardegna, 24.12.85, Bauladu (OR), S. Vittore, leg. Leo ” “ Neochthonius leoi n. sp. ♀ paratypus, Callaini det.” (MSNV).

Other material examined. ITALY — Sardinia: Cagliari Prov. — 1 ♀, Villacidro, Foresta di Monte Mannu, 8.XI.1986, P. Leo leg. Sardinia: Nuoro Prov. — 1 ♀, Dualchi, 8.XII.1992, P. Leo leg.

Description of adults (♀, ♂ unknown). Integument slightly pigmented, carapace, tergites, chelicerae and pedipalps pale brown; weak hispid granulation on the lateral surfaces of carapace, on cheliceral palm and on the base of fixed chelal finger. Carapace 1.1–1.15 times longer than broad, quadrate, weakly constricted posteriorly; anterior margin between median macrosetae with a prominent epistome, with sharp denticles (Fig. 309); no eyes or eye-spots; chaetotaxy 4:6:4:2:4(20), lateral setae of posterior row mostly shorter than median ones; length of anteromedian macrosetae 0.05–0.06 mm. Chaetotaxy of tergites 4:4:4:4:6:6:6:6:1T2T1:4:1T2T1:0. Chaetotaxy of sternites 10:(3)8(3):(2)7–8(2):8–9:6:6:6:6:2T1T2:0:2. Chelicerae 2.0–2.05 times as long as broad, palm with 6 setae and 1 or 2 lateral microsetae; fixed finger with 7–9 teeth; movable finger with an isolated subapical tooth (di) more proximal than the spinneret, and 8–9 teeth proximally reduced in size; gs ratio 0.60; spinneret prominent; rallum with 11 blades; serrula exterior with 14 blades. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 3 marginal microsetae, II 4, III 6, IV 7; coxa II with 5–6 coxal spines, coxa III with 3–4 coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 3.6–3.95 times as long as broad, femoral chaetotaxy 3:5:2:5:1; chela 4.35–4.45 times as long as deep; hand of chela 1.55–1.65 times as long as deep, ovoid in dorsal view (Fig. 310); fixed chelal finger with 42–54 contiguous teeth, tall and rectangular in the distal half of the finger, apically truncated in the proximal half; all teeth with dental canal; fixed finger at level of est-it (Fig. 311) with about 11 teeth occupying 0.05 mm; tip of fixed chelal finger with apical sensilla af 1- 2 , distal paraxial seta gradually curved and thin; movable chelal finger with 41–53 contiguous teeth, similar to those of fixed chelal finger, apically rounded from st towards the finger base; movable finger at level of st-t (Fig. 311) with about 11 teeth occupying 0.05 mm; coupled sensilla pc mainly just distad of sb, on a weak tubercle; tip of movable chelal finger with apical sensilla am 1- 2 ; trichobothrium sb halfway between b and st; ratio of movable finger/hand of chela 1.8–1.85; ratio of pedipalpal femur/movable finger 0.9–0.95; ratio of pedipalpal femur/carapace 0.9–1.0.

Measurements (in mm). Body length 0.85–0.9. Carapace 0.23–0.26 × 0.26–0.28. Chelicerae 0.225 –0.235 × 0.11–0.115; movable finger length 0.115–0.12. Pedipalp: femur 0.235 –0.255 × 0.06–0.065; chela 0.38–0.40 × 0.85– 0.09; hand length 0.14; movable finger length 0.225 –0.265.

Remarks. Among the species of the Chthonius ischnocheles group, C. leoi is morphologically similar to the epigean C. caprai from Liguria, Sicily and Sardinia, and to C. jonicus that is also known from Sardinia.

Chthonius leoi differs from C. caprai in the following main characters: anterior margin of carapace without preocular microsetae (mainly with 1 preocular microseta on each side in C. caprai); posterior margin of carapace with 4 macrosetae (mainly with 6 macrosetae in C. caprai). Differences in the shape and size of chelal finger teeth between C. leoi and C. caprai —highlighted by Callaini (1988) —are not confirmed after examination of specimens belonging to both species.

Chthonius leoi differs from C. jonicus in the following main characters: eyes absent (anterior eyes with flat lens, posterior eyes reduced to a pale cuticular area in C. jonicus); chelicerae with 1 or 2 lateral microsetae (without lateral microsetae in C. jonicus); chela length 0.38–0.40 mm (0.40–0.51 mm in C. jonicus); movable chelal finger length 0.225 –0.265 mm (0.275–0.34 mm in C. jonicus); movable chelal finger with coupled sensilla pc on a noticeable tubercle (coupled sensilla pc not on a tubercle in C. jonicus).

Considerations about a probable synonymy between Chthonius caprai and C. leoi are given in the Remarks under C. caprai.