Chthonius italicus Beier, 1930

Gardini, Giulio, 2021, The Italian species of the Chthonius ischnocheles group (Arachnida, Pseudoscorpiones, Chthoniidae), with reference to neighbouring countries, Zootaxa 4987 (1), pp. 1-131 : 88-91

Chthonius italicus Beier, 1930

( Figs 266–281 , 413 )

Chthonius (Chthonius) italicus Beier, 1930: 72 .

Chthonius cephalotes: Ellingsen 1909: 212 .

Type locality: Italy, Piedmont, Cuneo Province, Chiusa di Pesio, subterranean galleries under Certosa di Pesio (44°14’27”N, 7°39’44”E) .

Distribution. France (Eastern Provence Pre-Alps), Italy (Southern Cottian, Maritimes and Ligurian Alps).

Diagnosis (♂ ♀). An anophthalmic hypogean Chthonius that differs from other species of the ischnocheles group in the following combination of characters: anterior margin of carapace with a weak epistome and with 1 preocular microseta on each side; posterior margin of carapace with 2 macrosetae and 1 (rarely 2) lateral microseta on each side; chelicerae with 2 (rarely 1) lateral microsetae; chela length 1.26–1.76 mm; movable chelal finger length 0.86–1.20 mm; chela 6.25–7.5 times as long as deep; fixed chelal finger slightly curved; chelal fingers with contiguous teeth; fixed and movable chelal fingers with 58–83 and 46–53 teeth respectively; fixed and movable chelal fingers at level of est -ist and st -t respectively, with 5–9 and 4–7 teeth occupying 0.1 mm, distance between successive apices 0.011 –0.018 and 0.014 –0.023 mm respectively; ratio of pedipalpal femur/carapace 1.7–1.85.

Type material examined. ITALY — Piedmont: 1 ♂ (holotype), “ Sotterranei della Certosa di Pesio , VIII.1907, R. Gestro leg.” ( MSNG) .

Other material examined. FRANCE — Alpes-Maritimes — 1 ♂, Séranon , Grotte de Rouaïne, 1164 m a.s.l., 11. VIII.1991, E. Piva leg. ; 2 ♀, Sospel , Grotte de Albarea, 800 m a.s.l., 26.IV.1980, S. Zoia & A. Torchia leg. ; 1 ♀, Tende , Grotta della Besta 163–H, 19. VIII.1930, A. Dodero leg. ( MSNG) .

ITALY — Piedmont: Cuneo prov . — 1 ♂, Monterosso Grana, Pozzo l’Angiulin 1346 Pi / CN, 919 m a.s.l., 11.VII.2014, E. Lana leg. ; 2 ♂, Roaschia, Buco del Dré 1006 Pi / CN, 1100 m a.s.l., 27. VI.2014, E. Lana leg. ; 1 ♀, Robilante, Grotta dei 3 Moschettieri 1129 Pi / CN, 1380 m a.s.l., 12.IX.2014, E. Lana & M. Chesta leg. Liguria: Imperia prov. — 2 ♀, Caravonica, Tana Ia du Casà 573 Li / IM, 715 m a.s.l., 22.IX.1974, C. Bonzano leg. ; 1 ♂ 2 ♀, Pigna, Grotta dei Surgentin 1169 Li / IM, 760 m a.s.l., 29.III.2015, A. Pastorelli leg. ; 1 ♀, id., 17.I.2016, A. Pastorelli leg.

Description of adults (♂ ♀). Troglomorphic facies; integument slightly pigmented, carapace, tergites, chelicerae and pedipalps pale reddish brown; weak hispid granulation on lateral surfaces of carapace, on cheliceral palm and on the base of fixed and movable chelal fingers. Carapace ( Fig. 268 ) 0.9–1.0 times longer than broad, trapezoidal, constricted posteriorly; anterior margin between median macrosetae with a weak epistome in both sexes ( Figs 266–267 ); ocular area as in fig. 268, no eyes or eye-spots; probable standard chaetotaxy m 4m:6:4:2:m 2m (22), but anterior row also m4 and posterior row also m2, m 2mm or mm 2mm; length of anteromedian macrosetae 0.155 – 0.185 mm. Standard chaetotaxy of tergites 4:4:4:4:6:6:6:6:1T2T1:4:1T2T1:0, tergite I rarely with 2 or 3, tergite II rarely with 3 setae. Chaetotaxy of sternites 10:(3)8–10(3):(2)7–8(2):8:6:6:6:6:2T1T2:0:2; genital opening of males flanked by 8 (rarely 9) setae on each side. Chelicerae ( Fig. 269 ) 2.4–2.5 (♂ ♀) times as long as broad, palm with 6 setae and 2 (rarely 1) lateral microsetae; fixed finger with 9–12 teeth and 4–5 proximal microtubercles; movable finger with an isolated subapical tooth (di) situated more proximal with respect to the spinneret, and 9–12 teeth proximally reduced in size; gs ratio 0.51–0.55; spinneret weakly raised or right angle-shaped in males, more prominent in females ( Figs 269–271 ); rallum with 11 blades; serrulae interior and exterior with 14–16 and 15–18 blades respectively. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 3 marginal microsetae, II 4, III 5, IV 6; coxa II with 7–15 coxal spines, coxa III with 4–5 coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 6.85–7.7 (♂) or 6.6–7.3 (♀) times as long as broad, femoral chaetotaxy 3:5(6):3(4):5(6):1; chela ( Figs 274, 278 ) 7.05–7.5 (♂) or 6.25–6.8 (♀) times as long as deep; hand of chela 2.2–2.4 (♂) or 1.95–2.2 (♀) times as long as deep, with almost parallel sides in dorsal view ( Figs 272–273 ); fixed chelal finger slightly curved, with 58–83 contiguous teeth, cuspidate and inclined backwards in the distal half of the finger, apically rounded and increasingly reduced towards finger base in the proximal half of the finger ( Figs 275–277, 279–281 ), all teeth with dental canal; base of fixed chelal finger with 4–6 microtubercles; fixed finger at level of est-it with 5–9 teeth occupying 0.1 mm, distance between successive apices 0.011 –0.018 mm; tip of fixed chelal finger with apical sensilla af 1- 2, distal paraxial seta gradually curved and thin; movable chelal finger with 46–53 contiguous teeth, scalene triangle-shaped, reclined and apically pointed in the distal third of the finger, apically rounded and increasingly reduced towards finger base, reaching back near b (between sb and b they are mainly recognizable only by the presence of dental canal) ( Figs 275–277, 279–281 ); movable finger at level of st-t with 4–7 teeth occupying 0.1 mm, distance between successive apices 0.014 –0.023 mm; coupled sensilla pc mainly just distad of sb; tip of movable chelal finger with apical sensilla am 1- 2; trichobothria as in figs 274, 278; ratio sb -st/sb -b = 1.6–1.8; ratio of movable finger/hand of chela 2.1–2.25 (♂) or 2.0–2.2 (♀); ratio of pedipalpal femur/movable finger 1.0–1.05 (♂ ♀); ratio of pedipalpal femur/ carapace 1.7–1.85 (♂ ♀).

Measurements (in mm). Body length 1.8–2.15 (♂) or 2.2–2.4 (♀). Carapace 0.52–0.58 × 0.52–0.60 (0.50–0.575 anteriorly) (♂) or 0.62–0.69 × 0.67–0.68 (0.66–0.67 anteriorly) (♀). Chelicerae 0.56–0.64 × 0.23–0.255 (♂) or 0.675–0.75 × 0.265–0.30 (♀); movable finger length 0.28–0.32 (♂) or 0.35–0.39 (♀). Pedipalp: femur 0.90–1.08 × 0.13–0.14 (♂) or 1.09–1.27 × 0.15–0.175 (♀); chela 1.26–1.54 × 0.17–0.205 (♂) or 1.50–1.76 × 0.23–0.27 (♀); hand length 0.405 –0.475 (♂) or 0.47–0.58 (♀); movable finger length 0.86–1.07 (♂) or 1.02–1.20 (♀).

Remarks. Among the species of the Chthonius ischnocheles group, C. italicus is morphologically very close to the subterranean C. lanai from the Cottian Alps and, to a lesser degree, to C. cephalotes ( Simon, 1875) from the Provence, France.

Chthonius italicus differs from C. lanai in the following characters: eyes absent (anterior eyes reduced to a smooth cuticular area in C. lanai ); chaetotaxy of tergites I–IV (2–3)4:3–4:4:4 (2:2–3:4: 4 in C. lanai ); fixed chelal finger slightly curved (straight in C. lanai ); fixed and movable chelal fingers with smaller and more closely-set teeth ( Figs 275–277, 279–281 ) [with larger and more widely spaced teeth ( Figs 305–307 ) in C. lanai ].

Chthonius cephalotes was described from a single female that was collected in the cave Grotte des Baux (Les- Baux-de-Provence, France) and redescribed by Heurtault-Rossi (1968). Both C. cephalotes and C. italicus show corresponding measurements, a reduced epistome, relative position of trichobothria esb-ist and est-it, and the same chelal tooth pattern. They differ in the position of trichobothrium sb (ratio sb -st/sb -b = 2.2 in C. cephalotes , 1.6–1.8 in C. italicus ) and in the chaetotaxy of the carapace ( C. cephalotes without preocular microsetae and with 2 macrosetae on posterior margin, without lateral microsetae; C. italicus with 1 preocular microseta on each side and with 2 macrosetae and 1 or 2 microsetae on each side on posterior margin).

Figures

FIGURES 266–273. Chthonius italicus Beier, 1930, Grotta dei Surgentin, 29.III.2015 (Pigna, Imperia) (unless otherwise stated). 266, male, anterior margin of carapace; 267, female, id.; 268, male, carapace; 269, male, right chelicera; 270, female, movable finger of right chelicera; 271, male (Buco del Dré, Roaschia), id.; 272, male, right chelal hand, dorsal view; 273, female, id.

FIGURES 274–281. Chthonius italicus Beier, 1930, Grotta dei Surgentin, 29.III.2015 (Pigna, Imperia). 274, male, right chela, antiaxial view; 275, male, detail of fingers at the chelal tip, antiaxial view; 276, male, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 277, male, detail of fingers at level of trichobothrium sb, antiaxial view; 278, female, right chela, antiaxial view; 279, female, detail of fingers at the chelal tip, antiaxial view; 280, female, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 281, female, detail of fingers at level of trichobothrium sb, antiaxial view.

FIGURES 410–413. Distribution maps for the Italian species of the Chthonius ischnocheles group. 410, Chthonius caoduroi Callaini, 1987, Chthonius gallettii n. sp., Chthonius inguscioi n. sp., Chthonius marciai n. sp. and Chthonius multidentatus Beier, 1963; 411, Chthonius caprai Gardini, 1977, Chthonius jonicus Beier, 1931 and Chthonius leoi (Callaini, 1988); 412, Chthonius halberti Kew, 1916, Chthonius nicolosii n. sp., Chthonius ressli Beier, 1956 and Chthonius stammeri Beier, 1942; 413, Chthonius horridus Beier, 1934, Chthonius italicus Beier, 1930 and Chthonius lanai n. sp.

FIGURES 304–308. Chthonius lanai n. sp. 304, female holotype, right chela, antiaxial view; 305, female holotype, detail of fingers at the chelal tip, antiaxial view; 306, female holotype, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 307, female holotype, detail of fingers at level of trichobothrium sb, antiaxial view; 308, male paratype, right chela, antiaxial view.