Chthonius herminii, Gardini, 2021

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 : 60-62

Chthonius herminii n. sp.

( Figs 173–187 , 409 )

Type locality: Italy, Veneto, Treviso Province, Cavaso del Tomba, Costalunga , Speoncia del Diaol 1811 V / TV (45°50’51”N, 11°54’25”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 strongly denticulate, without prominent epistome, and with 1 preocular microseta on each side; posterior margin of carapace with 2 macrosetae, without lateral microsetae; chelicerae with 1 lateral microseta; chela length 0.90–1.06 mm; chela 5.3–6.0 times as long as deep; chelal fingers with contiguous teeth; fixed and movable chelal fingers with 55–62 and 48–52 teeth respectively; ratio of pedipalpal femur/carapace 1.3–1.5.

Type material. ITALY — Veneto: 1 ♂ (holotype) 2 ♀ (paratypes), Treviso Prov., Cavaso del Tomba, Costalunga , Speoncia del Diaol 1811 V / TV (45°50’51”N, 11°54’25”E), 275 m a.s.l., 24. V.1998, G. Peretto & E. Piva leg. ; 1 ♂ (paratype), id., 18.X.1996, E. Piva leg.; 1 ♀ (paratype), id., 4. V.1997, G. Peretto & E. Piva leg.; 1 ♀ (paratype), id., 3. VIII.1997, E. Piva leg.; 1 ♀ (paratype), id., 11.I.1998, E. Piva leg.; 2 ♀ (paratypes), id., 15.XI.1998, G. Peretto & E. Piva leg.; 2 ♀ (paratypes), id., 27. VI.1999, G. Peretto & E. Piva leg.; 1 ♂ 2 ♀ (paratypes), id., 16.VII.2000, G. Peretto & E. Piva leg. (holotype deposited in MHNG, paratypes in G. Gardini coll., Genoa) .

Derivatio nominis. The species is dedicated to Erminio Piva (Club Speleologico Proteo, Vicenza) in appreciation of his contributions to the knowledge of the subterranean fauna of Veneto.

Description of adults (♂ ♀). Troglomorphic facies; integument slightly pigmented, carapace, tergites, chelicerae and pedipalps pale brown; weak hispid granulation on lateral surfaces of carapace, on cheliceral palm and on base of fixed chelal finger. Carapace ( Fig. 175 ) 0.9–1.0 times longer than broad, trapezoidal, constricted posteriorly; anterior margin between median macrosetae with strong and prominent denticles in both sexes ( Figs. 173–174 ); ocular area as in fig. 175, anterior eyes reduced, with flat lens, posterior eyes absent; distance from anterior eyes to anterior margin of carapace 0.040 mm; standard chaetotaxy m 4m:6:4:2:2(20), rarely ocular row with 7 (holotype), median row with 5 setae (1 ♂ 1 ♀); length of anteromedian macrosetae 0.11–0.13 mm. Chaetotaxy of tergites 4:4: 4:4:6:6:6:6:1T2T1:4:1T2T1:0. Chaetotaxy of sternites 10:(3)6–10(3):(2)6–7(2):8–9:6–7: 6–7: 6–7: 6–7:2T1T2:0:2; genital opening of males flanked by 6–9 setae on each side. Chelicerae ( Fig. 176 ) 2.25–2.3 (♂) or 2.1–2.25 (♀) times as long as broad, palm with 6 setae and 1 lateral microseta; fixed finger with 2 distal large teeth followed by 6–9 small teeth proximally reduced in size; movable finger with an isolated subapical tooth (di) just distad (♂) or at level (♀) of the spinneret, followed by a large tooth and 7–9 teeth proximally reduced in size; gs ratio 0.52–0.56; spinneret weakly raised in males, more prominent, large and rounded in females; rallum with 11 blades; serrulae interior and exterior with 14–15 and 14–16 blades respectively. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 3 marginal microsetae, II 4(5), III 5, IV 6(7); coxa II with 5–8 coxal spines, coxa III with 3–5 coxal spines; intercoxal tubercle bisetose (1m in holotype). Pedipalp: femur 5.2–5.45 (♂) or 5.0–5.25 (♀) times as long as broad, femoral chaetotaxy 3:5:2:5:1; chela ( Figs 180, 184 ) 5.75–6.0 (♂) or 5.3–5.6 (♀) times as long as deep; hand of chela 1.75–1.80 (♂) or 1.65–1.70 (♀) times as long as deep, ovoid in dorsal view ( Figs 178–179 ); fixed chelal finger with 55–62 contiguous teeth, cuspidate and inclined backwards in the distal half of the finger, apically rounded in the proximal half ( Figs 181–183, 185–187 ); all teeth with dental canal; base of fixed chelal finger with 3–6 microtubercles; fixed finger at level of est-it with 6–9 teeth occupying 0.1 mm, distance between successive apices 0.011 –0.017 mm; tip of fixed chelal finger with apical sensilla af 1- 2, distal paraxial seta gradually curved and thin; movable chelal finger with 48–52 contiguous teeth, reclined and apically pointed in the distal third of the finger, apically rounded and increasingly reduced towards finger base, reaching back to level of b; between sb and b teeth mainly recognizable only by the presence of dental canal ( Figs 181–183, 185–187 ); movable finger at level of st-t with 6–8 teeth occupying 0.1 mm, distance between successive apices 0.012 –0.016 mm; coupled sensilla pc just distad of sb, on a weak tubercle; tip of movable chelal finger with apical sensilla am 1- 2; trichobothria as in figs 180, 184; ratio sb -st/sb -b = 1.8; ratio of movable finger/hand of chela 2.2–2.4 (♂ ♀); ratio of pedipalpal femur/movable finger 0.9–1.0 (♂ ♀); ratio of pedipalpal femur/carapace 1.3–1.5 (♂ ♀).

Measurements (in mm). Body length 1.3–1.5 (♂ ♀). Carapace 0.40–0.41 × 0.41–0.46 (0.395–0.45 anteriorly) (♂) or 0.48–0.51 × 0.50–0.51 (0.48–0.49 anteriorly) (♀). Chelicerae 0.44 × 0.19–0.195 (♂) or 0.50–0.53 × 0.225–0.24 (♀); movable finger length 0.225–0.23 (♂) or 0.26–0.27 (♀). Pedipalp: femur 0.58–0.60 × 0.11–0.115 (♂) or 0.655–0.71 × 0.13–0.135 (♀); chela 0.90–0.93 × 0.15–0.16 (♂) or 1.0–1.06 × 0.185–0.19 (♀); hand length 0.27–0.28 (♂) or 0.305 –0.315 (♀); movable finger length 0.63–0.65 (♂) or 0.70–0.75 (♀).

Remarks. Among the species of the Chthonius ischnocheles group, C. herminii n. sp. is most similar to the subterranean C. euganeus from which it differs in the following characters: anterior eyes with flat lens, posterior eyes absent in C. herminii (no eyes in C. euganeus ); chelicerae with 1 lateral microseta (with 2–3 lateral microsetae in C. euganeus ); fixed and movable chelal fingers (♂ ♀) with 55–62 and 48–52 teeth respectively (60–84 and 50–59 in C. euganeus ); fixed and movable chelal fingers (♂ ♀) at level of est -ist and st -t, respectively, with 6–9 and 6–8 teeth occupying 0.1 mm, distance between successive apices 0.011 –0.017 and 0.012 –0.016 mm respectively (with 9–11 and 9–10 teeth occupying 0.1 mm, distance between successive apices 0.009 –0.011 and 0.010 –0.011 mm, respectively, in C. euganeus ); ratio of movable finger/hand of chela (♂ ♀) 2.2–2.4 (1.9–2.1 in C. euganeus ).

Figures

FIGURES 173–179. Chthonius herminii n. sp., Speoncia del Diaol (Cavaso del Tomba, Treviso). 173, male holotype, anterior margin of carapace; 174, female paratype (24.V.1998), id.; 175, male holotype, carapace; 176, male holotype, right chelicera; 177, female paratype (24.V.1998), movable finger of right chelicera; 178, male holotype, right chelal hand, dorsal view; 179, female paratype (24.V.1998), id.

FIGURES 180–187. Chthonius herminii n. sp., Speoncia del Diaol (Cavaso del Tomba, Treviso). 180, male holotype, right chela, antiaxial view; 181, male holotype, detail of fingers at the chelal tip, antiaxial view; 182, male holotype, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 183, male holotype, detail of fingers at level of trichobothrium sb, antiaxial view; 184, female paratype (24.V.1998), right chela, antiaxial view; 185, female paratype (24.V.1998), detail of fingers at the chelal tip, antiaxial view; 186, female paratype (24.V.1998), detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 187, female paratype (24.V.1998), 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.