Chthonius comottii Inzaghi, 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 : 27-31

Chthonius comottii Inzaghi, 1987

( Figs 77–96 , 402 )

Chthonius (C.) comottii Inzaghi, 1987: 166 , figs 1–16.

Chthonius (C.) comottii: De Vore-Scribante 1999: 6 , 70, 126, 219, 261, figs 2a–e.

Type locality: Italy, Lombardy, Bergamo Province, Oneta, Mine below the Refuge Grem (45°52’52”N, 9°49’34”E)

Distribution. Switzerland (Tessin), Italy (from Bergamasque Pre-Alps to Ligurian Alps).

Diagnosis (♂ ♀). A microphthalmic epigean or hypogean Chthonius that differs from other species of the ischnocheles group in the following combination of characters: anterior margin of carapace with 1 (rarely 2) preocular microseta on each side; posterior margin of carapace with 2 macrosetae and mainly with 1 lateral microseta on each side; chelicerae with 2 (rarely 1) lateral microsetae; chela length 0.715–1.20 mm; movable chelal finger length 0.495–0.81 mm; fixed and movable chelal fingers with 26–50 and 26–40 teeth, respectively; chelal fingers with reclined, pointed and widely spaced teeth; both fixed and movable chelal fingers at level of est-ist and st-t with 4–6 teeth occupying 0.1 mm, distance between successive apices 0.016 –0.034 mm; movable chelal finger with coupled sensilla pc situated on a noticeable tubercle; ratio of pedipalpal femur/carapace 1.3–1.6.

Material examined. ITALY — Lombardy: Bergamo Prov. — 2 ♂ 1 ♀, Colzate, Baite Sedernello, 1300 m a.s.l., 11.X.1989, M. Valle leg. ; 1 ♀, Dossena, 1100 m a.s.l., 14.VII.1990, M. Grottolo leg., beech wood; 1 ♀, id., 1.XI.1991, L. Latella leg. Lombardy: Como Prov. — 2 ♀, Centro Valle Intelvi, Monte Generoso , 1400 m a.s.l., 11. VI.1986, D. Baratelli leg. , deep digging; 1 ♂, Centro Valle Intelvi, Monte Generoso, Bocche di Orimento , 1300 m a.s.l., 29.X.1987, D. Baratelli leg. , deep digging; 2 ♀, id., 24.IV.1988, D. Baratelli leg., deep digging; 1 ♂, Valsolda– Dasio, near Alpe Mapel , 1250 m a.s.l., 8.VII.1995, S. Zoia leg. Lombardy: Lecco Prov. — 1 ♀, Lecco, Monte Barro , 800 m a.s.l., 24.XI.1990, S. Zoia leg. ; 1 ♀, Paderno d’Adda, 220 m a.s.l., 30. VI.1990, S. Zoia leg. Piedmont: Biella Prov. — 7 ♂, Biella, near Santuario di Oropa, 1050 m a.s.l., 8.XII.1979, S. Zoia leg. ; 1 ♂, Sagliano Micca, Miniera Passobreve A n. 1, 3. VI.2020, D. Trombin leg.; 1 ♀, Sagliano Micca, Miniera Passobreve A n. 2, 3. VI.2020, D. Trombin leg. Piedmont: Cuneo Prov. — 1 ♂ 2 ♀, Barge, Madonna della Rocca , Buco del Bryaxis 1325 Pi / CN, 529 m a.s.l., 9. VI.2013, E. Lana & M. Chesta leg. ; 1 ♂ 3 ♀, Bernezzo, Pertus d’la Kassetta 1323 Pi / CN, 1230 m a.s.l., 27.X.2019, E. Lana & M. Chesta leg. ; 2 ♀, Bossea, 1200 m a.s.l., 8.X.1986, S. Zoia leg., beech wood; 2 ♂, Boves, San Giacomo , 850 m a.s.l., 26.X.1993, G.B. Delmastro leg. ; 5 ♂ 4 ♀, Castelmagno, Chiappi, near Torrente Grana , 1600 m a.s.l., 5. VIII.1999, G.B. Delmastro leg. ; 9 ♂ 2 ♀, Cervasca, Colle di San Maurizio , 850 m a.s.l., 26.X.1993, G.B. Delmastro leg. ; 1 ♀, Dronero, Tana della Volpe di Dronero 1205 Pi / CN, 645 m a.s.l., 14.IX.2014, E. Lana & M. Chesta leg. ; 2 ♂, Garessio, N slope of Mt. Galero , 1300 m a.s.l., 29. V.1976, G. Gardini leg. , beech wood; 1 ♂, Ormea, slope of Mt. Armetta , 1000 m a.s.l., 25.IX.1976, G. Gardini & S. Zoia leg. ; 1 ♂, Pesio, Pian delle Gorre , 1500 m a.s.l., 17. VI.1973, G. Gardini leg. , sieved under Acer ; 1 ♂, Pesio, Pian delle Gorre, near Torrente Pesio , 1000 m a.s.l., 16.X.1977, N. Sanfilippo leg. , beech wood; 1 ♂, Pradleves, Vallone Pentenera , 900 m a.s.l., 30.XII.1991, G.B. Delmastro leg. ; 1 ♀, Robilante, Grotta T.A.C. 2 n. c. Pi / CN, 965 m a.s.l., 14.IV.2014, E. Lana & M. Chesta leg. ; 1 ♂ 1 ♀, Roburent, San Giacomo di Roburent , 1000 m a.s.l., 30.X.1994, G. Gardini leg. , beech wood; 1 ♂, Roburent, San Giacomo di Roburent, Tana di San Luigi 112 Pi / CN, 780 m a.s.l., 10.X.2009, M. Evangelista leg .; 3 ♂, Roccaforte Mondovì, near Rastello , 1400 m a.s.l., 24.X.1985, G. Gardini, A. Rey & S. Zoia leg. , beech wood; 1 ♂, Roccasparvera, underground of the castle of Rocca Sparvera , 8.XI.2014, E. Lana & M. Chesta leg. ; 1 ♂ 4 ♀, Roccavione, Tetto Cherro, 710 m a.s.l., 16.XI.1993, G.B. Delmastro leg.; 1 ♀, Sampeyre, Foresto , 1300 m a.s.l., 24. VIII.1986, G. Gardini leg. ; 1 ♂ 1 ♀, Valgrana, Cavaliggi, 685 m a.s.l., 30.XII.1991, G.B. Delmastro leg.; 1 ♀, Valmala, near Santuario di Valmala, 1380 m a.s.l., 13. VIII.1995, S. Zoia leg.; 2 ♂ 2 ♀, Viozene, Selle di Carnino , 1900 m a.s.l., 15. VIII.1968, A. Vigna leg. , beech wood. Piedmont: Novara Prov. — 1 ♂ 1 ♀, Armeno, Miniere dell’Alpe Cervec art. Pi /NO, 631 m a.s.l., 9. V.2015, E. Lana & G.D. Cella leg. Piedmont: Turin Prov. — 5 ♂, Torino , Basilica di Superga, 640 m a.s.l., 19.III.1999, G.B. Delmastro leg. ; 1 ♂, Villar Pellice , VII.1973, G. Bartoli leg. Piedmont: Vercelli Prov. — 1 ♂, Ara, Monte Fenera , 5.IV.1986, M. Bodon leg. ; 1 ♀, Borgosesia, Monte Fenera, Tana dell’Armittu 2690 P/VC, 20.III.1997, A. Balestrieri leg. ; 1 ♂, id., 4. V.1997, T. Pascutto leg. ; 1 ♀, Borgosesia, Grotta dell’Uomo Libero 2665 Pi /VC, 620 m a.s.l., 12.II.2014, E. Lana leg. ; 2 ♀, Borgosesia, Monte Fenera, Buco della Bondaccia 2505 Pi /VC, 690 m a.s.l., 9.IV.2000, T. Pascutto & S. Bugalla leg. ; 2 ♀, id., 30.IX.2000, T. Pascutto, S. Bugalla & F. Stoch leg. ; 1 T, Borgosesia, Monte Fenera, R –5 del Fenera 2743 Pi /VC, 529 m a.s.l., 13.IX.2013, E. Lana & R. Sella leg. ; 1 ♀, Civiasco, Monte Falconera, Grotta del Teschio 2614 Pi /VC, 765 m a.s.l., T. Pascutto & R. Palestro leg. ; 2 ♀, Valduggia, Bocc d’la Mocia 2541 Pi /VC, 29.III.2014, E. Lana leg. ; 1 ♀, Valduggia, Buco dello Scoiattolo 2748 Pi /VC, 676 m a.s.l., 2.IV.2013, E. Lana leg. ; 1 ♀, Valduggia, Fratturata 2747 Pi /VC, 669 m a.s.l., 2.IV.2013, E. Lana leg. Liguria: Imperia Prov. — 2 ♂, Baiardo, slope of Mt. Cavanelle , 6.XI.1981, S. Zoia, G. Gardini & A. Boato leg. ; 1 ♂, Bordighera, Sasso , 9.XI.1974, G. Gardini leg. , under stone in olive grove. Liguria: Savona Prov. — 2 ♀, Bardineto, Roveirola , 3.X.1989, G. Gardini, R. Rizzerio & G. Troiano leg. ; 1 ♂, Calizzano, Colle del Melogno , 1000 m a.s.l., 29. V.1979, S. Zoia leg.

Description of adults (♂ ♀). Integument slightly pigmented, carapace, tergites, chelicerae and pedipalps pale brown; weak hispid granulation on lateral surface of carapace, on cheliceral palm and on base of fixed chelal finger. Carapace ( Fig. 79 ) trapezoidal, constricted posteriorly, 0.8–1.0 times longer than broad; anterior margin between median macrosetae strongly denticulate or with a prominent epistome in both sexes ( Figs 77–78 ); ocular area as in fig. 79, anterior eyes reduced, with flat lens (diameter 0.030 –0.045 mm) and tapetum, posterior ones absent or as vestigial remains; standard chaetotaxy m 4m:6:4:2:m 2m (22), anterior row rarely with mm 4m or mm 4mm, posterior row rarely without lateral microsetae (♂ from Castelmagno, Chiappi) or mm 2m; length of anteromedian macrosetae 0.11–0.15 mm. Chaetotaxy of tergites 4:4:4:4:6:6:6:6:1T2T1:4:1T2T1:0. Chaetotaxy of sternites II–X: 10–11:(3)8–10(3):(2)8(2):7–8:8:6:6:6:2T1T2; genital opening of males flanked by 7–9 (rarely 5 or 6) setae on each side. Chelicerae ( Fig. 80 ) 2.15–2.35 (♂ ♀) times as long as broad, palm with 6 setae and 2 (rarely 1) lateral microsetae; fixed finger with 2 large distal teeth followed by 6–9 small teeth proximally reduced in size and a few proximal microtubercles; movable finger with an isolated subapical tooth (di) at level or just proximad of the spinneret, followed by a large tooth and 7–10 teeth proximally reduced in size; gs ratio 0.50–0.59; spinneret weakly raised in males ( Fig. 80 ), more prominent and rounded in females ( Fig. 81 ); rallum with 11 blades; serrulae interior and exterior with 13–15 and 14–16 blades respectively. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 3 marginal microsetae, II 4, III 5, IV 6; coxa II with 7–12 coxal spines, coxa III with 2–6 (mainly 4–6) coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 4.9–5.9 (♂) or 4.7–6.1 (♀) times as long as broad, femoral chaetotaxy 3:5:3:5:1; chela ( Figs 84, 88 ) 5.3–6.35 (♂) or 4.75–5.95 (♀) times as long as deep; hand of chela 1.7–2.0 (♂) or 1.55–1.95 (♀) times as long as deep, with long ovoid outline in dorsal view ( Figs 82–83 ); fixed chelal finger with 26–50 teeth inclined backwards: 7–14 small, pointed and more or less contiguous distal teeth (up to the level of et), proximally increasing in size, followed by large, sharp, reclined and widely spaced teeth, decreasing in size from middle finger towards finger base; 8–20 proximal teeth low, more contiguous, rounded and gradually reduced in size ( Figs 85–87, 89–91 ); all teeth with dental canal; fixed finger at level of est-it with 4–6 (♂ ♀) teeth occupying 0.1 mm, distance between successive apices 0.016 –0.027 (♂) or 0.017 –0.034 (♀) mm; tip of fixed chelal finger with apical sensilla af 1- 2, distal paraxial seta gradually curved and thin; movable chelal finger with 26–40 teeth, slightly scalene triangle-shaped, reclined and apically pointed proximally up to halfway between trichobothria st -sb, then rounded or flattened towards finger base, reaching back near b (between sb and b they are mainly recognizable only by the presence of dental canal) ( Figs 85–87, 89–91 ); movable finger at level of st-t with 4–6 (♂ ♀) teeth occupying 0.1 mm, distance between successive apices 0.016 –0.023 (♂) or 0.016 –0.028 (♀) mm; coupled sensilla pc mainly distad of sb or halfway between sb -st, rarely nearer to st than to sb and always on a noticeable tubercle; tip of movable chelal finger with apical sensilla am 1- 2; trichobothria as in figs 84, 88; ratio sb -st/sb -b = 1.6–2.0; ratio of movable finger/hand of chela 1.9–2.3 (♂ ♀); ratio of pedipalpal femur/movable finger 0.9–1.0 (♂ ♀); ratio of pedipalpal femur/carapace 1.3–1.6 (♂ ♀).

Measurements (in mm). Body length 1.2–1.6 (♂) or 1.4–2.0 (♀). Carapace 0.36–0.46 × 0.37–0.48 (0.34–0.44 anteriorly) (♂) or 0.37–0.56 × 0.42–0.63 (0.40–0.60 anteriorly) (♀). Chelicerae 0.35–0.47 × 0.16–0.21 (♂) or 0.40–0.58 × 0.18–0.26 (♀); movable finger length 0.185–0.25 (♂) or 0.21–0.32 (♀). Pedipalp: femur 0.47–0.70 × 0.09–0.12 (♂) or 0.51–0.79 × 0.105–0.14 (♀); chela 0.715–1.02 × 0.12–0.165 (♂) or 0.775–1.20 × 0.14–0.225 (♀); hand length 0.225–0.35 (♂) or 0.245–0.42 (♀); movable finger length 0.495–0.70 (♂) or 0.53–0.81 (♀).

Remarks. Chthonius comottii was described by Inzaghi (1987) based on epigean and subterranean specimens (8 males and 9 females) from six localities in the Bergamasque and Varese Pre-Alps. Following the finding of the variability in anterior eyes development, the length and slenderness of palpal chelae, and the number and shape of chelal fingers teeth, the author thought it possible to distinguish two “ecological races”, informally called A and B. On the basis of the data published by Inzaghi (1987), these two forms possess, respectively: anterior eyes reduced to eye-spots (A), anterior eyes with flat lens (B); length of palpal chela 0.825–0.93 mm (♂) or 0.89–0.97 mm (♀) (A), 0.76–0.79 mm (♂) or 1.0– 1.1 mm (♀) (B); palpal chela 5.8–6.15 (♂) or 5.4–5.7 (♀) (A), 5.45–5.6 (♂) or 5.1–5.3 (♀) (B) times as long as deep; ratio of movable finger/hand of chela 2.2–2.3 (♂) or 2.1–2.25 (♀) (A), 2.0–2.05 (♂) or 2.0 (♀) (B); number of teeth of the fixed chelal finger 49–53 (♂) or 43–46 (♀) (A), 35–38 (♂) or 32–38 (♀) (B); number of teeth of the movable chelal finger 37–40 (♂) or 35–40 (♀) (A), 31–36 (♂) or 30–31 (♀) (B).

The specimens examined here as Chthonius comottii share, with rare exceptions (see the above Description of adults), the same carapacal chaetotaxy (m 4m:6:4:2:m 2m), the presence of 2 lateral microsetae on the cheliceral palm, a weakly raised spinneret in males and the coupled sensilla pc lodged between sb -st on a noticeable tubercle. The anterior eyes are always reduced to a flat lens, rarely almost absent, but with the tapetum still present (♀ from Buco dello Scoiattolo, Valduggia). The measurements and ratios vary widely within the range of the species and include most of those detected by Inzaghi (1987); the specimens with larger dimensions are the subterranean ones from the caves near Borgosesia and Valduggia, province of Vercelli, which also show a wide intra-populational variability [Tana dell’Armittu (♂ ♀): palpal chela length 1.02–1.20 mm, movable chelal finger 0.70–0.81 mm; Bocc d’la Mocia (♀): palpal chela length 1.07–1.17 mm, movable chelal finger 0.705–0.78 mm]. As emphasized by Inzaghi (1987: 174, footnote 2), large specimens usually have more widely spaced chelal teeth, while smaller specimens have closer teeth. Regardless of size, the most evident variability in dentition concerns the shape and the reciprocal distance of distal teeth of the fixed chelal finger, as shown in figs 92–96, which represents the range of variability of the dentition of the chelal fingers. The variability of the epistome ( Figs 77–78 ) is much wider than that described by Inzaghi (1987: 170, figs 10–11, 13–15). The size of specimens from Tessin (Generoso Mt.) measured by De Vore- Scribante (1999) is sometimes (carapace, palpal femur, chelal finger) a little higher than that reported here.

The high variability of Chthonius comottii indicates that this is a species-complex that current morphological taxonomy is unable to detect.

Among the species of the Chthonius ischnocheles group, C. comottii is related to the epigean or hypogean C. agazzii , known from Friuli to Trentino. Both species share the presence of 1 preocular microseta on each side, a similar chelal pattern, the same number of chelal teeth and the movable chelal finger with coupled sensilla pc lodged on a noticeable tubercle. C. comottii differs from C. agazzii mainly in the following characters: posterior margin of carapace with 1 microseta on each side (with 2 macrosetae, without lateral microsetae in C. agazzii ); chelicerae with 2 lateral microsetae (with 1 microseta in C. agazzii ).

Chthonius comottii and C. agazzii are vicariant in the Alps: the first from Lombardy to western Liguria, the latter from Friuli to Trentino.

Figures

FIGURES 77–83. Chthonius comottii Inzaghi, 1987, Baite Sedernello (Colzate, Bergamo). 77, male, anterior margin of carapace; 78, female, id.; 79, male, carapace; 80, male, right chelicera; 81, female, movable finger of right chelicera; 82, male, right chelal hand, dorsal view; 83, female, id.

FIGURES 84–91. Chthonius comottii Inzaghi, 1987, Baite Sedernello (Colzate, Bergamo). 84, male, right chela, antiaxial view; 85, male, detail of fingers at the chelal tip, antiaxial view; 86, male, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 87, male, detail of fingers at level of trichobothrium sb, antiaxial view; 88, female, right chela, antiaxial view; 89, female, detail of fingers at the chelal tip, antiaxial view; 90, female, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 91, female, detail of fingers at level of trichobothrium sb, antiaxial view.

FIGURES 92–96. Chthonius comottii Inzaghi, 1987, detail of chelal fingers dentition at level of trichobothria dx-et (top), it- est/t-st (middle) and b (bottom), antiaxial view (setae and sensilla af1-2, am1-2 omitted). 92, male, Sasso (Bordighera, Imperia); 93, female, Bocc d’la Mocia (Valduggia, Vercelli); 94, female, Chiappi (Castelmagno, Cuneo); 95, female, San Giacomo di Roburent (Cuneo); 96, female, Colle San Maurizio (Cervasca, Cuneo).

FIGURES 402–405. Distribution maps for the Italian species of the Chthonius ischnocheles group. 402, Chthonius agazzii Beier, 1966 and Chthonius comottii Inzaghi, 1987; 403, Chthonius alpicola Beier, 1951; 404, Chthonius carinthiacus Beier, 1951; 405, Chthonius guglielmii Callaini, 1986 and Chthonius ilvensis Beier, 1963.