Chthonius caoduroi Callaini, 1987

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 : 15-16

Chthonius caoduroi Callaini, 1987

( Figs 41–48 , 410 )

Chthonius (C.) caoduroi Callaini, 1987: 69 , figs Ia–f.

Type locality: Italy, Basilicata, Potenza Province, Trecchina, Grotta Sant’Angelo 40 B/PZ (40°00’49”N, 15°48’17”E) .

Distribution. Italy (Basilicata).

Diagnosis (♂ ♀). A microphthalmic hypogean Chthonius that differs from other species of the ischnocheles group in the following combination of characters: anterior margin of carapace with a wide and prominent epistome and with 1 preocular microseta on each side; posterior margin of carapace with 2 macrosetae and 1 lateral microseta on each side; anterior eyes reduced, with flat lens; tergite I with 2 or 3 setae; chelicerae with 2 or 3 lateral microsetae; chela length 1.28–1.44 mm; movable chelal finger length 0.88–0.97 mm; chela 6.2–6.8 times as long as deep; chelal fingers with contiguous teeth; fixed and movable chelal fingers with 64–71 and 39–53 teeth respectively; fixed and movable chelal fingers at level of est -ist and st -t, respectively, with 6–7 and 5 teeth occupying 0.1 mm, distance between successive apices 0.014 –0.015 and 0.018 –0.020 mm respectively; ratio of pedipalpal femur/carapace 1.6–1.7.

Material examined. ITALY — Basilicata: Potenza Prov. — 2 ♀, Trecchina, Grotta Sant’Angelo 40 B/PZ, 22.IX.1991, R. Sciaky leg.

Description of adults (♂ ♀). Integument slightly pigmented, carapace, tergites, chelicerae and pedipalps pale brown; weak hispid granulation on lateral surface of carapace, cheliceral palm and on base of fixed chelal finger. Carapace ( Fig. 42 ) 0.9–1.1 times longer than broad, trapezoidal, constricted posteriorly; anterior margin between median macrosetae with wide and prominent epistome in both sexes (♀: fig. 41); ocular area as in fig. 42, anterior eyes reduced, with flat lens (diameter 0.032 mm), posterior eyes absent; distance from anterior eyes to anterior margin of carapace 0.040 mm [no eyes or eye-spots according to Callaini (1987)]; chaetotaxy m 4m:6:4:2:m 2m (22), posterior row m 2 in a female; length of anteromedian macrosetae 0.16 mm, macrosetae thick. Chaetotaxy of tergites 2–3:4:4:4:6:6:6:6:1T2T1:4:1T2T1:0. Chaetotaxy of sternites 9–12:(3)7–9(3):(2)7–9(2):7–9:6:6:6:6:2T1T2:0:2; genital opening of males flanked by 9–10 setae on each side. Chelicerae ( Fig. 43 ) 2.3–2.4 (♂) or 2.2–2.25 (♀) times as long as broad, palm with 6(7) setae and 2 or 3 lateral microsetae; fixed finger with 12–16 teeth; movable finger with an isolated subapical tooth (di) at level with the spinneret, and 10–13 teeth proximally reduced in size; gs ratio 0.56–0.62; spinneret weakly raised in males, more prominent, large and rounded in females; rallum with 11 blades; serrulae interior and exterior with 14 and 15–16 blades respectively. Coxal setae: pedipalp 5(6) (including 2 on manducatory process), I 3(4) + 3 marginal microsetae, II 4, III 5, IV 6; coxa II with 5–9 coxal spines, coxa III with 4–6 coxal spines; intercoxal tubercle with 3 (♂) or 2 microsetae (♀). Pedipalp: femur 6.35–6.55 (♂ ♀) times as long as broad, femoral chaetotaxy 3:5–6:2:5–6:1; chela ( Fig. 45 ) 6.7–6.8 (♂) or 6.2–6.4 (♀) times as long as deep; hand of chela 2.1–2.15 (♂) or 2.0–2.05 (♀) times as long as deep, with almost parallel sides in dorsal view ( Fig. 44 ); fixed chelal finger with 64–71 contiguous teeth inclined backwards, all cuspidate except the proximal ones (about 13–18) apically rounded ( Figs 46–48 ); all teeth with dental canal; base of fixed chelal finger with about 8 microtubercles; fixed finger at level of est-it with 6–7 teeth occupying 0.1 mm, distance between successive apices 0.014 –0.015 mm; tip of fixed chelal finger with apical sensilla af 1- 2, distal paraxial seta gradually curved and thin; movable chelal finger with 39–53 more widely spaced teeth, scalene triangle-shaped, reclined and apically pointed in the distal half of the finger, apically rounded and increasingly reduced towards finger base, reaching back halfway between sb and b ( Figs 46–48 ); base of movable chelal finger with about 4 microtubercles; movable finger at level of st-t with 5 teeth occupying 0.1 mm, distance between successive apices 0.018 –0.020 mm; coupled sensilla pc just distad of sb; tip of movable chelal finger with apical sensilla am 1- 2; trichobothria as in fig. 45; ratio sb -st/sb -b = 1.45–1.9; ratio of movable finger/hand of chela 2.0–2.2 (♂ ♀); ratio of pedipalpal femur/movable finger 0.95–1.0 (♂ ♀); ratio of pedipalpal femur/carapace 1.6–1.7 (♂ ♀).

Measurements (in mm). Body length 1.7–1.9 (♂) or 2.0–2.1 (♀). Carapace 0.50–0.51 × 0.54–0.55 (♂) or 0.53–0.58 × 0.60–0.64 (♀). Chelicerae 0.56–0.59 × 0.24–0.25 (♂) or 0.59–0.66 × 0.26–0.29 (♀); movable finger length 0.30–0.31 (♂) or 0.32–0.36 (♀). Pedipalp: femur 0.835 –0.865 × 0.12–0.13 (♂) or 0.89–0.95 × 0.14–0.145 (♀); chela 1.28–1.30 × 0.19 (♂) or 1.30–1.44 × 0.205–0.23 (♀); hand length 0.405–0.41 (♂) or 0.42–0.475 (♀); movable finger length 0.88–0.89 (♂) or 0.89–0.97 (♀).

Remarks. Chthonius caoduroi was described by Callaini (1987) from three males and three females that were collected in the cave Grotta Sant’Angelo (Trecchina, Basilicata), so far the only locality known for the species. I agree with Callaini (1987) in considering C. caoduroi morphologically similar to the subterranean C. multidentatus from Sicily from which it differs in the following main characters: anterior eyes with flat lens, posterior reduced to a pale cuticular area (eyes absent in C. multidentatus ); tergite I with 2 or 3 setae (4 setae in C. multidentatus ); fixed and movable chelal fingers (♂ ♀) with 64–71 and 39–53 teeth respectively (83–97 and 60–77 in C. multidentatus ); fixed and movable chelal fingers (♂ ♀) at level of est -ist and st -t, respectively, with 6–7 and 5 teeth occupying 0.1 mm, distance between successive apices 0.014 –0.015 and 0.018 –0.020 mm respectively (with 11–12 and 7–10 teeth occupying 0.1 mm, distance between successive apices 0.008 –0.009 and 0.010 –0.014 mm, respectively, in C. multidentatus ); ratio of pedipalpal femur/carapace (♂ ♀) 1.6–1.7 (1.35–1.55 in C. multidentatus ).

Chthonius caoduroi is also morphologically similar to the subterranean C. gallettii from Sicily and C. inguscioi from Apulia. It differs from C. gallettii in the following main characters: anterior margin of carapace with 1 preocular microseta on each side (2 preocular microsetae in C. gallettii ); tergite I with 2 or 3 setae (4 setae in C. gallettii ); male chela length 1.28–1.30 mm, 6.7–6.8 times as long as deep (1.52 mm, 7.4 times as long as deep in C. gallettii ); fixed and movable chelal fingers of males with 66–71 and 39–43 teeth respectively (70 and 50 in C. gallettii ).

Chthonius caoduroi differs from the hypogean C. inguscioi from Apulia in the following main characters: anterior margin of carapace with 1 preocular microseta on each side (2 preocular microsetae in C. inguscioi ); tergite I with 2 or 3 setae (4 setae in C. inguscioi ); male chela length 1.28–1.30 mm, 6.7–6.8 times as long as deep (0.8–1.0 mm, 6.25–6.3 times as long as deep in C. inguscioi ); fixed and movable chelal fingers (♂ ♀) at level of est -ist and st -t, respectively, with 6–7 and 5 teeth occupying 0.1 mm, distance between successive apices 0.014 –0.015 and 0.018 –0.020 mm respectively (with 11–12 and 9–10 teeth occupying 0.1 mm, distance between successive apices 0.009 and 0.009 –0.011 mm respectively, in C. inguscioi ).

The above description of Chthonius caoduroi partially incorporates the one of Callaini (1987).

Figures

FIGURES 41–44. Chthonius caoduroi Callaini, 1987, female, Grotta Sant’Angelo (Trecchina, Potenza). 41, anterior margin of carapace; 42, carapace; 43, right chelicera; 44, right chelal hand, dorsal view.

FIGURES 45–48. Chthonius caoduroi Callaini, 1987, female, Grotta Sant’Angelo (Trecchina, Potenza). 45, right chela, antiaxial view; 46, detail of fingers at the chelal tip, antiaxial view; 47, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 48, 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.