Chthonius

Gardini, Giulio, 2013, A revision of the species of the pseudoscorpion subgenus Chthonius (Ephippiochthonius) (Arachnida, Pseudoscorpiones, Chthoniidae) from Italy and neighbouring areas, Zootaxa 3655 (1), pp. 1-151 : 97-99

Chthonius (E.) poseidonis Gardini, 1993

(Figs 187–190, 285)

Chthonius (Ephippiochthonius) poseidonis Gardini 1993b: 75 , figs 1–6. Chthonius (E.) poseidonis : Gardini 2008a: 7, figs 7–10.

Type locality: Italy, Sardinia, Sassari Prov., Alghero, Grotta di Nettuno 65 Sa/SS (40°33ʹ39ʺN 8°09ʹ50ʺE).

Distribution. Italy: Sardinia.

Diagnosis (Ƥ). A hypogean Chthonius (Ephippiochthonius) from Sardinia that differs from other species of the C. tetrachelatus group in the following combination of characters: movable cheliceral finger with spinneret in both sexes and without isolated subapical tooth (di); posterior margin of carapace with 2 macrosetae; fixed and movable chelal finger respectively with 21–25 and 9–12 triangular teeth; fixed chelal finger at level of est-it with 3 teeth occupying 0.1 mm (distance between successive apices 0.035–0.042 mm); length of chela 1.21–1.41 (3), 1.16–1.60 (Ƥ) mm, length of movable chelal finger 0.71–0.80 (3), 0.67–0.94 (Ƥ) mm; chela 6.4–6.7 (3), 5.6–6.1 (Ƥ) times as long as deep; ratio of pedipalpal femur/carapace 1.5–18 (3Ƥ).

Type material examined. ITALY— Sardinia: Sassari Prov.— 1 3 (holotype), Alghero, Capo Caccia, Grotta di Nettuno 65 Sa/SS, 2 m a.s.l., 22.VIII.1990, M. Mucedda leg.; 1 Ƥ (paratype), id., 23.XII.1989, M. Mucedda leg.; 1D (paratype), id., Capo Caccia, Grotta del Soffio (= Gruta del Buf) 1389 Sa/SS, 52 m a.s.l., 28.I.1990, I. Panoutsopoulos leg.

Other material examined. ITALY— Sardinia: Oristano Prov.— 1 3, Cuglieri, Tegas, Grotta di Cappas 181 Sa/OR, 193 m a.s.l., 2.IV.2005, G. Grafitti leg., on decomposing organic matter at 70 m from the entrance. Sardinia: Sassari Prov.— 3 3 1 Ƥ, id., Capo Caccia, Grotta di Nettuno 65 Sa/SS, 2 m a.s.l., 17.I.1993, A. Molinu, G. Murittu & M. Mucedda leg., on dry concretions at 200 m from the entrance; 1T, id., 24.VI.1995, M. Mucedda leg., under stone in the tourist gallery; 1 3, id., 18.III.2005, M. Mucedda leg.; 1 Ƥ, id., Capo Caccia, Grotta del Soffio (= Gruta del Buf) 1389 Sa/SS, 52 m a.s.l., 25.VIII.1993, M. Mucedda leg., on wall of the first karst well; 1 3, Mara, Tuva ‘e Mare, Grotta Tuva ‘e Mare 94 Sa/SS, 525 m a.s.l., 1.III.1992, G. Grafitti leg., under stone; 4 Ƥ, id., 19.XII.1999, F. Camboni & M. Mucedda leg.

Description of adults (Ƥ). Weakly marked troglomorphic facies. Integument depigmented or with weak pigmentation, carapace, chelicerae and pedipalps mostly testaceous; hispid granulation on lateral surface of carapace, cheliceral palm and base of movable chelal finger. Carapace 1.0–1.1 times longer than broad, posteriorly constricted; anterior margin (fig. 187) finely denticulate between median macrosetae, without (Gr. di Nettuno) (fig. 188) or with (Gr. Tuva ‘e Mare) evident epistome; eyes variously developed: missing (Gr. di Cappas), or the anterior ones reduced to a pale cuticular area (Gr. Tuva ‘e Mare) or completely developed (Gr. di Nettuno), in latter case the anterior eyes with convex lens (diameter 0.049–0.056 mm, distance to anterior margin of carapace 0.050– 0 0 60 mm), the posterior ones with flat lens, all eyes with tapetum; chaetotaxy mm(or m) 4mm (or m):6:4:2:2(18), macrosetae fine; 1 or 2 preocular microsetae on each side, rarely 1 or 3 on one side; length of anteromedian macrosetae 0.14–0.16 mm. Chaetotaxy of tergites I–X 4:4:4:4:6:6:6:6:6:4. Chaetotaxy of sternites II–X 10:(3)8(3):(2)7(2):8:6:6:6:6:7; sternite II rarely with 11 or 14 setae, st. III rarely with (4)9–10(4) setae, sternite IV rarely with (2)8(2) setae, sternite V rarely with 10 setae; genital opening of males mostly flanked by 6–11 setae on each side. Chelicerae (fig. 189) 2.0–2.4 times as long as broad, palm with 6 or 7 setae and 2 microsetae laterally, fixed finger with 7–11 teeth and about 5 proximal microtubercles; movable finger with 7–10 teeth proximally reduced in size and about 5 proximal microtubercles; movable finger without isolated subapical tooth (di); gl ratio 0.58–0.62; spinneret weakly raised in males, prominent, conical and apically rounded in females; rallum with 11 blades; serrula exterior with 14–17 blades. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 3 marginal microsetae, II 4, III 5, IV 6 (rarely 7); coxa II with 9–17 coxal spines, coxa III with 5–9 coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 6.6–8.1 (3), 6.9–7.4 (Ƥ) times as long as broad; chela (fig. 190) 6.4– 6.7 (3), 5.6–6.1 (Ƥ) as long as deep; hand of chela 2.5–2.9 (3), 2.2–2.5 (Ƥ) times as long as deep, weakly depressed proximally ib-isb (with a weak hump distad of ib-isb in specimens from Gr. di Cappas and Gr. di Tuva ‘e Mare); 187–190. Chthonius (E.) poseidonis Gardini, 1993 (male holotype). 187, anterior margin of carapace; 188, anterolateral portion of carapace; 189, fingers of right chelicera; 190, right chela, lateral view (redrawn after Gardini, 1993b).

fixed chelal finger with 23–27 teeth: 2–3 proximal teeth apically rounded, the others triangular, sharp, proximally reduced in size, all teeth with dental canals; tip of fixed chelal finger with a modified accessory tooth (td) on antiaxial face; fixed chelal finger at level of est-it with 3 teeth occupying 0.1 mm (distance between successive apices 0.035–0.042 mm); distal half of movable chelal finger with 1 or 2 very small distal teeth and 8–11 triangular, upright, sharp teeth; proximal half of movable chelal finger with vestiges of 8–15 teeth back to trichobothrium sb (or a little proximad of sb), all teeth with dental canals; coupled sensilla pc nearer to sb than to b (rarely a little distad of sb); trichobothria as in fig. 190, eb-esb-ist mostly placed in a straight line, rarely ist at level of esb; basal apodeme of movable chelal finger strongly sclerotized, mostly narrow, rectangular; ratio of movable finger/hand of chela 1.35–1.6 (3Ƥ); ratio of pedipalpal femur/movable finger 1.1–1.3 (3Ƥ); ratio of pedipalpal femur/carapace 1.5–18 (3Ƥ).

Measurements (in mm). Body length 1.8–2.3 (3), 2.2–2.5 (Ƥ). Carapace 0.57–0.60 × 0.53–0.58 (0.48–0.55 anteriorly) (3), 0.54–0.58 × 0.51–0.68 (0.48–0.64 anteriorly) (Ƥ). Chelicerae 0.50–0.55 × 0.21–0.26 (3), 0.50– 0.64 × 0.22–0.315 (Ƥ), movable finger length 0.25–0.27 (3), 0.24–0.30 (Ƥ). Pedipalp: femur 0.83–1.05 × 0.12– 0.135 (3), 0.84–1.18 × 0.12–0.16 (Ƥ); chela 1.21–1.41 × 0.19–0.21 (3), 1.16–1.60 × 0.20–0.27 (Ƥ); hand length 0.47–0.61 (3), 0.46–0.66 (Ƥ); movable finger length 0.71–0.80 (3), 0.67–0.94 (Ƥ).

Description of tritonymph. Integument depigmented. Carapace 0.95 times longer than broad, posteriorly slightly constricted, anterior margin denticulate, without epistome; anterior eyes with flat lens, no posterior eyes; chaetotaxy m 4m:6:4:2:2(18). Chaetotaxy of tergites as in adults. Chaetotaxy of sternites II–X 4:(2)6(2):(1)6(1):7:6:6:6:6:6. Chelicerae 2.1 times as long as broad, palm with 5 setae and 1 microseta laterally; fixed finger with 6–7 teeth proximally reduced in size; movable finger with 6 teeth, without isolated subapical tooth (di); spinneret prominent; gl ratio 0.60; rallum with 9 blades; serrula exterior with about 12 blades. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 2 marginal microsetae, II 4, III 5, IV 5; coxa II with 7 coxal spines, coxa III with 3 coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 6.5 times as long as broad; chela 6.7 times as long as deep; hand of chela 2.8 times as long as deep; fixed chelal finger with 18 triangular teeth proximally reduced in size back to the finger base, followed by 4 proximal microtubercles; tip of fixed finger with a modified accessory tooth (td) on antiaxial face; distal half of movable chelal finger with 10 triangular teeth (the distal one very small) with dental canals and, in the proximal half, with vestiges of 9 teeth without dental canals; ratio of movable finger/hand of chela 1.4; ratio of pedipalpal femur/movable finger 1.2; ratio of pedipalpal femur/ carapace 1.6.

Measurements (in mm). Body length 1.4. Carapace 0.43 × 0.45 (0.41 anteriorly). Chelicerae 0.38 × 0.18, movable finger length 0.19. Pedipalp: femur 0.68 × 0.105; chela 0.94 × 0.14; hand length 0.39; movable finger length 0.55.

Remarks. Among the species of the Chthonius tetrachelatus group, C. poseidonis is closely related to the hypogean C. grafittii from NW Sardinia, from which it differs in minor troglomorphic facies: chela 6.4–6.7 (3) 5.6–6.1 (Ƥ) times as long as deep in C. poseidonis , 6.85 (3) 6.1–6.5 (Ƥ) times as long as deep in C. grafittii ; fixed chelal finger with 21–25 triangular teeth in C. poseidonis , with 18–22 triangular teeth in C. grafittii .

Gardini (2008) noted morphological differences between subterranean Sardinian populations, but nevertheless referred them all to C. poseidonis . A similar taxonomic difficulty—due to shortage of specimens—is mentioned in regard to C. concii .