Chthonius inguscioi, 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 : 72-75

Chthonius inguscioi n. sp.

( Figs 229–236 , 410 )

Type locality: Italy, Apulia, Lecce Province, Presicce, Grotta Madonna della Rutta 533 Pu / LE (39°55’10”N, 18°16’23”E) .

Distribution. Italy (Apulia).

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 2 preocular microsetae on each side; posterior margin of carapace with 4 macrosetae (lateral setae shorter than the median ones); chelicerae with 3 lateral microsetae; chela length 0.88–1.0 mm; movable chelal finger length 0.595–0.68 mm; chelal fingers with contiguous teeth; both fixed and movable chelal fingers at level of est-it and st-t with 8–11 teeth occupying 0.1 mm.

Type material. ITALY — Apulia: 1 ♂ (holotype), Lecce Prov., Presicce, Grotta Madonna della Rutta 533 Pu / LE, 10.VII.1999, S. Inguscio & R. Pepe leg. ; 2 ♂ (paratypes), id., 14.VII.2019, S. Inguscio leg. (holotype deposited in MHNG, paratypes in G. Gardini coll., Genoa) .

Derivatio nominis. Named after its collector, the naturalist and biospeleologist Salvatore Inguscio (Laboratorio Ipogeo Salentino di Biospeleologia “Sandro Ruffo”, Nardò, Lecce), in recognition of his contribution to the knowledge of the subterranean fauna of Apulia.

Description of adults (♂; ♀ unknown). 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. 230 ) 0.90 times longer than broad, trapezoidal, constricted posteriorly; anterior margin denticulate between median macrosetae and with a prominent, sharp epistome ( Fig. 229 ); ocular area as in fig. 230, anterior eyes reduced, with flat lens (diameter 0.035 mm), posterior eyes absent; distance from anterior eyes to anterior margin of carapace 0.045 mm; chaetotaxy mm 4mm:6:4:2:4(24), length of anteromedian macrosetae 0.135 mm, lateral setae of posterior row half as long as the median setae. Chaetotaxy of tergites 4:4:4:4:6:6:6:6:1T 2T1:4:1T2T1:0. Chaetotaxy of sternites 10:(3)10(3):(2)8(2):8:6:6:6:6:2T2T2:0:2; genital opening flanked by 7–7 setae. Chelicerae ( Fig. 231 ) 2.15–2.3 times as long as broad, palm with 6 setae and 3 lateral microsetae; fixed finger with 2 distal large teeth followed by 7–8 small teeth; movable finger with an isolated subapical tooth (di) at level with the spinneret, followed by a large tooth and 8–9 teeth proximally reduced in size; gs ratio 0.56–0.62; spinneret weakly raised; rallum with 11 blades; serrulae interior and exterior both with 14–15 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 4–6 coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 5.4–5.65 times as long as broad, femoral chaetotaxy 3:6:2:5:1; chela ( Fig. 233 ) 6.25–6.3 times as long as deep; hand of chela 2.05–2.1 times as long as deep, with parallel sides in dorsal view ( Fig. 232 ); fixed chelal finger with 68–77 contiguous teeth, cuspidate and slightly inclined backwards in the distal two thirds of the finger, rounded and increasingly reduced in the proximal third ( Figs 234–236 ), all teeth with dental canal; fixed finger at level of est-it with 11–12 teeth occupying 0.1 mm, distance between successive apices 0.009 mm; tip of the fixed chelal finger with apical sensilla af 1- 2, distal paraxial seta gradually curved and thin; movable chelal finger with 53–56 more widely spaced teeth, slightly scalene triangle-shaped, reclined and apically pointed from finger’s tip to halfway between trichobothria sb -st, rounded and increasingly reduced towards finger base ( Figs 234–236 ); movable finger at level of st-t with 9–10 teeth occupying 0.1 mm, distance between successive apices 0.009 –0.011 mm; coupled sensilla pc just distad sb; tip of movable chelal finger with apical sensilla am 1– 2; trichobothria as in fig. 233; ratio sb -st/sb -b = 1.65; ratio of movable finger/hand of chela 2.0–2.05; ratio of pedipalpal femur/movable finger 1.0; ratio of pedipalpal femur/carapace 1.5.

Measurements (in mm). Body length 1.5. Carapace 0.45 × 0.49 (0.47 anteriorly). Chelicerae 0.41–0.48 × 0.19– 0.21; movable finger length 0.22–0.26. Pedipalp: femur 0.595 –0.675 × 0.105 –0.125; chela 0.88–1.0 × 0.14–0.16; hand length 0.29–0.34; movable finger length 0.595–0.68.

Remarks. Among the species of the Chthonius ischnocheles group, C. inguscioi n. sp. is morphologically similar to the subterranean C. multidentatus from Sicily, C. caoduroi from Basilicata and C. gallettii from Sicily.

Chthonius inguscioi differs from C. multidentatus in the following main characters: anterior eyes with flat lens, posterior eyes reduced to a pale cuticular area (no eyes in C. multidentatus ); anterior margin of carapace with 2 preocular microsetae on each side (1 preocular microseta in C. multidentatus ); fixed and movable chelal fingers of male with 68–77 and 53–56 teeth, respectively (male with 83 and 60 in C. multidentatus ).

Chthonius inguscioi differs from C. caoduroi in the following main characters: anterior margin of carapace with 2 preocular microsetae on each side (1 preocular microseta in C. caoduroi ); tergite I with 4 setae (2 or 3 setae in C. caoduroi ); male chela length 0.8–1.0 mm, 6.25–6.3 times as long as deep (1.28–1.30 mm, 6.7–6.8 times as long as deep in C. caoduroi ); fixed and movable chelal fingers at level of est -ist and st -t, 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 (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, in C. caoduroi ).

Chthonius inguscioi differs from C. gallettii in the following main characters: posterior margin of carapace with 4 macrosetae (with 2 macrosetae and 1 lateral microseta on each side in C. gallettii ); male chela length 0.88–1.0 mm, 6.25–6.3 times as long as deep (1.52 mm, 7.4 times as long as deep in C. gallettii ); fixed and movable chelal fingers at level of est -ist and st -t, 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 (with 9 and 6 teeth occupying 0.1 mm, distance between successive apices 0.011 and 0.017 mm, respectively, in C. gallettii ); ratio of pedipalpal femur/carapace 1.5 (1.75 in C. gallettii ).

Figures

FIGURES 229–232. Chthonius inguscioi n. sp., male holotype. 229, anterior margin of carapace; 230, carapace; 231, right chelicera; 232, right chelal hand, dorsal view.

FIGURES 233–236. Chthonius inguscioi n. sp., male holotype. 233, right chela, antiaxial view; 234, detail of dentition at the right chelal fingers tip, antiaxial view; 235, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 236, 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.