Chthonius gallettii, 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 : 45-48

Chthonius gallettii n. sp.

( Figs 127–134 , 410 )

Type locality: Italy, Sicily, Ragusa Province, Ragusa, Grotta delle Lame 6009 Si /RG (36°59’01”N, 14°43’59”E) .

Distribution. Italy (Sicily).

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 2 macrosetae and 1 lateral microseta on each side; chelicerae with 3 lateral microsetae; chela length 1.52 mm; movable chelal finger length 1.02 mm; chela 7.4 times as long as deep; chelal fingers with contiguous teeth; fixed and movable chelal fingers with 70 and 50 teeth respectively; fixed and movable chelal fingers at level of est -ist and st -t with 9 and 6 teeth occupying 0.1 mm, distance between successive apices 0.011 and 0.017 mm respectively; ratio of pedipalpal femur/carapace 1.75.

Type material. ITALY — Sicily: 1 ♂ (holotype), Ragusa Prov., Ragusa, Case Cardello , Grotta delle Lame 6009 Si /RG (36°59’01”N, 14°43’59”E), 620 m a.s.l., 3. VIII .1994, I. Galletti leg. ( MHNG) .

Derivatio nominis. Named after its collector, Dr Iolanda Galletti (C.I.R.S. Centro Ibleo di Ricerche Speleo- Idrogeologiche, Ragusa), in recognition of her contribution to the knowledge of the subterranean fauna of Sicily.

Description of adults (♂; ♀ unknown). Highly specialized 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 chelal hand. Carapace ( Fig. 128 ) 0.95 times longer than broad, trapezoidal, constricted posteriorly; anterior margin denticulate between median macrosetae, with a prominent epistome ( Fig. 127 ); ocular area as in fig. 128, anterior eyes reduced, with flat lens (diameter 0.025 mm), posterior eyes reduced to a pale cuticular area; distance from anterior eyes to anterior margin of carapace 0.030 mm; chaetotaxy mm 4mm:6:4:2:m 2m (24), anteromedian macrosetae removed from their alveola. Chaetotaxy of tergites 4:4:4:4:6: 6:6:6:1T2T1:4:1T2T1:0. Chaetotaxy of sternites 10:(3)10(3):(2)8(2):6:6:6:6:6:2T2T2:0:2; genital opening flanked by 10 and 11 setae. Chelicerae ( Fig. 129 ) 2.3 times as long as broad, palm with 6 setae and 3 lateral microsetae; fixed finger with 2 distal large teeth followed by 9 small teeth; movable finger with an isolated subapical tooth (di) at level of the spinneret, followed by a large tooth and 10 teeth that decrease in size proximally; gs ratio 0.56; spinneret weakly raised; rallum with 11 blades; serrulae interior and exterior both with 16 blades. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 3 marginal microsetae, II 4, III 5, IV 6; coxa II with 9 and 10 coxal spines, coxa III with 4 and 5 coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 6.6 times as long as broad, femoral chaetotaxy 3:6:2:5:1; chela ( Fig. 131 ) 7.4 times as long as deep; hand of chela 2.4 times as long as deep, with parallel sides in dorsal view ( Fig. 130 ); fixed chelal finger with 70 contiguous teeth, all cuspidate and slightly inclined backwards, except for the 5 proximal ones that are apically rounded ( Figs 132–134 ), all teeth with dental canal; fixed finger at level of est-it with 9 teeth occupying 0.1 mm, distance between successive apices 0.011 mm; tip of fixed chelal finger with apical sensilla af 1- 2, distal paraxial seta gradually curved and thin; movable chelal finger with 50 more spaced teeth, slightly scalene triangle-shaped, reclined and apically pointed from fingertip to trichobothrium sb, rounded and increasingly reduced from sb towards finger base, the proximal four teeth indicated only by the presence of dental canals ( Figs 132–134 ); movable finger at level of st-t with 6 teeth occupying 0.1 mm, distance between successive apices 0.017 mm; coupled sensilla pc closer to sb than to st; tip of movable chelal finger with apical sensilla am 1- 2; trichobothria as in fig. 131; ratio sb -st/sb -b = 2.0; ratio of movable finger/hand of chela 2.0; ratio of pedipalpal femur/movable finger 1.0; ratio of pedipalpal femur/carapace 1.75.

Measurements (in mm). Body length 1.9. Carapace 0.60 × 0.63 (0.59 anteriorly). Chelicerae 0.655 × 0.28; movable finger length 0.34. Pedipalp: femur 1.06 × 0.16; chela 1.52 × 0.205; hand length 0.50; movable finger length 1.02.

Remarks. Among the species of the Chthonius ischnocheles group, C. gallettii n. sp. is morphologically similar to the subterranean C. multidentatus from Sicily, C. caoduroi from Basilicata and C. inguscioi from Apulia. It 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 ); male chela length 1.52 mm, 7.4 times as long as deep (1.0 mm, 6.25 times as long as deep in C. multidentatus ); fixed and movable chelal fingers in male with 70 and 50 teeth, respectively (83 and 60 in C. multidentatus ); ratio of pedipalpal femur/carapace 1.75 (1.35–1.55 in C. multidentatus ).

Chthonius gallettii 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 1.52 mm, 7.4 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 in male with 70 and 50 teeth respectively (66–71 and 39–43 in C. caoduroi ).

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

Figures

FIGURES 127–130. Chthonius gallettii n. sp., male holotype. 127, anterior margin of carapace; 128, carapace; 129, right chelicera; 130, right chelal hand, dorsal view.

FIGURES 131–134. Chthonius gallettii n. sp., male holotype. 131, right chela, antiaxial view; 132, detail of dentition at the right chelal fingers tip, antiaxial view; 133, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 134, 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.