Chthonius paolettii Beier, 1973

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 : 108-111

Chthonius paolettii Beier, 1973

( Figs 350–357 , 409 )

Chthonius (C.) paolettii Beier, 1973: 159 , fig. 1.

Type locality: Italy, Veneto, Vicenza Province, Valstagna, Oliero , Covol degli Assassini 602 V / VI (= Covol degli Eccelini or Covol degli Ezzelini ) (45°50’41”N, 11°40’02”E) .

Distribution. Italy (Veneto).

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 1 preocular microseta on each side; posterior margin of carapace with 2 macrosetae, without lateral microsetae; chelicerae with 1 lateral microseta; chela length 1.10–1.15 mm; movable chelal finger length 0.74–0.77 mm; chelal fingers with reclined, pointed and widely spaced teeth; movable chelal finger with coupled sensilla pc not on a tubercle.

Material examined. ITALY — Veneto: Vicenza Prov. — 1 ♀, Valstagna, Oliero , Covol dei Siori 600 V / VI (= Grotta di Oliero or Grotta Parolini) (45°50’39”N, 11°40’01”E), 154 m a.s.l., 8.IV.1995, M. Grottolo leg.

Description of adults (♀; ♂ unknown). Integument slightly pigmented, reddish brown; weak hispid granulation on lateral surfaces of carapace, on cheliceral palm and on base of fixed and movable chelal finger. Carapace ( Fig. 351 ) 0.9 times longer than broad, trapezoidal, constricted posteriorly; anterior margin denticulate between median macrosetae and with a wide epistome ( Fig. 350 ); ocular area as in fig. 351, anterior eyes with flat lens (diameter 0.025 mm), posterior eyes absent, distance from anterior eyes to anterior margin of carapace 0.045 mm; chaetotaxy m 4m:6:4:2:2(20), length of anteromedian macrosetae 0.13, of preocular microsetae 0.037 mm. Chaetotaxy of tergites 4:4:4:4:6:6:6:6:1T2T1:4:1T2T1:0. Chaetotaxy of sternites II–X: 10:(3)9(3):(2)7(2):9:7:7:6:6:2T1T2. Chelicerae ( Fig. 352 ) 2.25 times as long as broad, palm with 6 setae and 1 lateral microseta; fixed finger with 10 teeth, of which the two distals are larger; movable finger with an isolated subapical tooth (di) more proximal with respect to the spinneret, a large tooth and 9 teeth proximally reduced in size; gs ratio 0.54; spinneret weakly prominent and widely rounded; rallum with 11 blades; serrula interior with 14, exterior with 18 blades. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 3 marginal microsetae, II 4, III 5, IV 6; coxa II with 7–9 coxal spines, coxa III with 2–5 coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 5.15–5.45 times as long as broad, femoral chaetotaxy 3:5:2:5:1; chela ( Fig. 354 ) 5.5–5.8 times as long as deep; hand of chela 1.8 times as long as deep, with long oval outline in dorsal view ( Fig. 353 ); fixed chelal finger with 45–47 teeth: 4 distal teeth flat (worn?), followed by 7 contiguous, triangular and slightly reclined teeth reaching back to et, 14 large, apically pointed, reclined and widely spaced teeth and 22 teeth that are increasingly reduced and closer together towards the finger base ( Figs 355–357 ); all teeth with dental canal; fixed finger at level of est-it with 3 teeth occupying 0.1 mm, distance between successive apices 0.035 mm; tip of fixed chelal finger with apical sensilla af 1- 2, distal paraxial seta gradually curved and thin; movable chelal finger with 45 teeth that are reclined, widely spaced and apically pointed in the distal half of the finger, broadly rounded apically and increasingly reduced towards finger base in the proximal half of the finger, reaching back halfway between sb -b (5–6 proximal teeth recognizable only by the presence of dental canal) ( Figs 355–357 ); movable finger at level of st-t with 5 teeth occupying 0.1 mm, distance between successive apices 0.025 mm; coupled sensilla pc nearer to sb than to st, not lodged on a tubercle; tip of movable chelal finger with apical sensilla am 1- 2; trichobothria as in fig. 354; ratio sb -st/sb -b = 1.4–1.7; ratio of movable finger/hand of chela 2.05–2.2; ratio of pedipalpal femur/movable finger 0.8–0.95; ratio of pedipalpal femur/carapace 1.5–1.55.

Measurements (in mm). Body length 1.3–1.6. Carapace 0.43–0.48 × 0.495–0.55. Chelicerae 0.52 × 0.23; movable finger length 0.28. Pedipalp: femur 0.67–0.71 × 0.13; chela 1.10–1.15 × 0.20; hand length 0.36–0.37; movable finger length 0.74–0.77.

Remarks. Among the species of the Chthonius ischnocheles group, C. paolettii is morphologically very close to C. agazzii , an epigean, or locally hypogean, species from the Eastern Alps. Chthonius paolettii differs from C. agazzii in the following characters (comparison only among females): chela length 1.10–1.15 mm (0.605–1.08 mm in C. agazzii ); movable chelal finger length 0.74–0.77 mm (0.42–0.74 mm in C. agazzii ); fixed and movable chelal fingers at level of est -ist and st -t, respectively, with 3 and 5 teeth occupying 0.1 mm, distance between successive apices 0.035 and 0.025 mm respectively (with 4–7 and 5–8 teeth occupying 0.1 mm, distance between successive apices 0.011 –0.032 and 0.011 –0.023 mm, respectively, in C. agazzii ); movable chelal finger with coupled sensilla pc not positioned on a tubercle (coupled sensilla pc lodged on a noticeable tubercle in C. agazzii ).

The above description of Chthonius paolettii partially incorporates the one of Beier (1973).

The caves Covol degli Assassini, type locality of Chthonius paolettii , and Covol dei Siori, where the female described above was collected, are interconnected (E. Piva, in litt.: February 14, 2020).

Figures

FIGURES 350–353. Chthonius paolettii Beier, 1973, female, Covol dei Siori (Valstagna, Vicenza). 350, anterior margin of carapace; 351, carapace; 352, left chelicera; 353, left chelal hand, dorsal view.

FIGURES 354–357. Chthonius paolettii Beier, 1973, female, Covol dei Siori (Valstagna, Vicenza). 354, left chela, antiaxial view; 355, id., detail of fingers at the chelal tip, antiaxial view; 356, id., detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 357, id., detail of fingers at level of trichobothrium sb, antiaxial view.

FIGURES 406–409. Distribution maps forthe Italian species of the Chthonius ischnocheles group.406, Chthonius densedentatus Beier, 1938; 407, Chthonius ischnocheles (Hermann, 1804); 408, Chthonius pygmaeus Beier, 1934; 409, Chthonius euganeus Gardini, 1991, Chthonius gentianae n. sp., Chthonius herminii n. sp. and Chthonius paolettii Beier, 1973.