Chthonius (Globochthonius) poeninus Mahnert, 1979

Gardini, Giulio, 2013, A revision of the species of the pseudoscorpion subgenus Chthonius (Ephippiochthonius) (Arachnida, Pseudoscorpiones, Chthoniidae) from Italy and neighbouring areas, Zootaxa 3655 (1), pp. 1-151 : 142-148

Chthonius (Globochthonius) poeninus Mahnert, 1979

( Figs 276–281 )

Chthonius ( Ephippiochthonius ?) poeninus Mahnert 1979: 504 , figs 1–5; DeVore-Scribante 1999: 20, 138, 225, 265, figs 14a–e; Muster et al. 2008: 21, fig. 1.

Type locality: Switzerland, canton Wallis, Susten (46°19ʹN 7°38ʹE).

Distribution. Germany (Bavaria), Switzerland.

Diagnosis (Ƥ). An eyed epigean Chthonius (Globochthonius) that differs from other species of the subgenus in the following combination of characters: pedipalpal hand (in lateral view) abruptly constricted distad of trichobothria ib-isb (fig. 279); fixed chelal finger weakly curved in lateral view, fixed and movable fingers with dense, triangular and reclined teeth.

Material examined. GERMANY— Bavaria: 2T, Allgäu Alps, Alpe Einödsberg, 1800 m a.s.l., IX.2004, H. Höfer & I. Harry leg. (CMP).

SWITZERLAND— Tessin: 2 3, Gole della Breggia, 5.XI.1985, A. Fossati leg.; 1 3, Val Carecchio, 1180 m a.s.l., 27.VI/ 12.VII.1988, P. Pronini leg., Fagus sylvatica wood (Barber); 1 Ƥ, Val Pontirone, 840 m a.s.l., 3– 13.VIII.1988, P. Pronini leg., broad-leaved mixed wood; 1 Ƥ, id., 1345 m a.s.l., 3–13.VIII.1988, P. Pronini leg., Picea excelsa wood.

Description of adults (Ƥ). Integument pigmented, carapace, tergites, chelicerae and pedipalps pale brown; hispid granulation on lateral surfaces of carapace, on cheliceral palm and on base of movable chelal finger. Carapace 0.9–1.0 times longer than broad, subquadrate, posteriorly slightly constricted; anterior margin (fig. 276) between median macrosetae strongly dentate, without epistome; ocular area as in fig. 277, anterior eyes with convex lens (diameter 0.045–0.047 mm), posterior ones with flat lens, all eyes with tapetum; distance from anterior eyes to anterior margin of carapace 0.030–0.035 mm; chaetotaxy m 4m:6:4:2:m 2m (18), rarely 2 preocular microsetae on each side; length of anteromedian macrosetae 0.09 mm. Chaetotaxy of tergites I–X 4:4:4:4:6:6:6:6:6:4. Chaetotaxy of sternites II–X 8–12:(3)8–12(3):(2)7–9(2):8:6:6:6:6:7; sternite II mostly with 10 setae, sternite IV mostly with (2)7(2) setae; genital opening of males flanked by 5–7 (mostly 6) setae on each side. Chelicerae (fig. 278) 2.2 (3), 2.05 (Ƥ) times as long as broad, palm with 6 setae and 2 microsetae laterally; fixed finger with 7–12 teeth and 5–6 proximal microtubercles; movable finger with a large isolated subapical tooth (di), at level with the spinneret, 5–10 teeth proximally reduced in size and 3–6 proximal tubercles; gl ratio 0.50–0.54; spinneret large, prominent and apically rounded, similar in both sexes; rallum with 11 blades; serrulae interior and exterior respectively with 12 and 14–16 blades. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 3 marginal microsetae, II 4, III 5, IV 6; coxa II with 6–10 coxal spines, coxa III with 3–6 coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 4.9–5.7 (3), 4.6–5.6 (Ƥ) times as long as broad; chela (fig. 279–280) 4.0–4.9 (3), 3.6–4.3 (Ƥ) times as long as deep; hand of chela 1.5–1.8 (3), 1.5–1.7 (Ƥ) times as long as deep, in lateral view with a marked dorsal hump and an abrupt dorsal slope distad of trichobothria ib-isb; fixed chelal finger with 24–30 teeth increasingly reclined and reduced towards the finger base: distal 2–3 teeth small, triangular, reclined, 15–17 large, triangular, reclined, with dental canals, proximally reduced in size, 10–13 small proximal teeth with rounded tips; base of fixed chelal finger with 2–3 microtubercles; tip of fixed finger with a sharp and prominent modified accessory tooth (td) on antiaxial face, without hollow on paraxial face in males or females (fig. 280); fixed finger at level of est-it with 6 teeth occupying 0.1 mm (distance between successive apices 0.018–0.023 mm); distal third of movable finger with 7–8 triangular, pointed, reclined teeth with dental canals and, proximad of trichobothrium st, with vestiges of 10–18 flat teeth gradually reduced in size, reaching back to halfway between st and sb, rarely back to sb; coupled sensilla pc nearer to sb than to b; trichobothria as in fig. 279, ist distad of the line eb-esb; basal apodeme of movable finger strongly sclerotized, short, squat, apically truncated; ratio of movable finger/hand of chela 1.4–1.6 (3), 1.4–1.5 (Ƥ); ratio of pedipalpal femur/movable finger 1.2 (3Ƥ); ratio of pedipalpal femur/ carapace 1.2–1.3 (3Ƥ).

Measurements (in mm). Body length 1.38–1.45 (3), 1.46 (Ƥ). Carapace 0.39–0.44 × 0.38–0.50 (3), 0.41–0.47 × 0.45–0.50 (Ƥ). Chelicerae 0.33 × 0.15 (3), 0.39 × 0.19 (Ƥ); movable finger length 0.17 (3), 0.21 (Ƥ). Pedipalp: femur 0.49–0.55 × 0.09–0.10 (3), 0.56–0.63 × 0.10–0.13 (Ƥ); chela 0.67–0.76 × 0.15–0.18 (3), 0.79–0.86 × 0.19– 0.23 (Ƥ); hand length 0.26–0.31 (3), 0.31–0.34 (Ƥ); movable finger length 0.39–0.44 (3), 0.46–0.49 (Ƥ).

Description of tritonymph. Integument with weak pigmentation, hispid granulation as in adults. Carapace 1.0 times longer than broad, form of anterior margin and eyes as in adults; diameter of anterior eyes 0.038 mm, distance from anterior eyes to anterior margin of carapace 0.035 mm; chaetotaxy m 4m:6:4:2:m 2m (18); length of anteromedian macrosetae 0.075 mm. Chaetotaxy of tergites as in adults. Chaetotaxy of sternites II–IX 5:(2)8(2):(1)6(1):7:6:6:6:6. Chelicerae 2.1 times as long as broad, palm with 5 (rarely 4) setae and one microseta laterally; fixed finger with 8–9 teeth, proximally reduced in size, and a few proximal microtubercles; movable finger with an isolated subapical tooth (di) and 4–5 teeth, the first 1 or 2 larger; gl ratio 0.51. Coxal setae: pedipalp 5 (including 2 on manducatory process), I 3 + 2 marginal microsetae, II 4, III 4, IV 5. Pedipalp: femur 4.4 times as long as broad; chela 3.9 times as long as deep; hand of chela 1.6 times as long as deep, with an abrupt dorsal slope distad of trichobothria ib-isb; fixed chelal finger with 19 teeth, all except proximal one with dental canals; tip of fixed finger with a modified accessory tooth (td) on antiaxial face, without hollow on paraxial face (fig. 281); movable chelal finger with 15 teeth, pointing backwards, to trichobothrium t, strongly reclined between t and st, proximally followed by vestiges of 7 flat teeth, dental canals not distinguishable; trichobothrium ist distad of line eb-esb; ratio of movable finger/hand of chela 1.0; ratio of pedipalpal femur/movable finger 1.15; ratio of pedipalpal femur/carapace 1.1.

Measurements (in mm). Body length 1.2. Carapace 0.32 × 0.31 (0.26 anteriorly). Chelicerae 0.27 × 0.13, movable finger length 0.145. Pedipalp: femur 0.35 × 0.08; chela 0.51 × 0.13; hand length 0.21; movable finger length 0.30.

Remarks. Mahnert (1979) described this remarkable species based on two males from the Swiss cantons of Wallis and Tessin. He expressed uncertainty about its attribution to Ephippiochthonius , since C. poeninus shows characteristics of both Globochthonius Beier, 1931 and Ephippiochthonius . DeVore-Scribante (1999) and Muster et al. (2008) accepted its attribution to Ephippiochthonius .

The present examination reveals the absence of a deep hollow on the paraxial face of the tip of the fixed chelal finger in males, females and tritonymphs of C. poeninus (figs 280–281). Since the presence of this character is shared by all studied species of Ephippiochthonius , this implies that C. poeninus do not belong to this subgenus. The chelal fingers of C. poeninus have the typical features for the species of the subgenus Chthonius : fixed chelal finger (in lateral view) weakly curved, fixed and movable fingers with less spaced, triangular and reclined teeth (fig. 279). However, the same type of dentition is also present in C. (G.) abnormis Beier, 1939. The basal apodeme of movable chelal finger (fig. 279) is very similar in shape to the ones of C. (G.) globifer Simon, 1879 and C. (G.) spelaeophilus Hadži, 1930 (see Gardini 2010, figs 7–8, 11, 19–20). The pedipalpal hand of C. poeninus (in lateral view, fig. 279) resembles in shape the hand of most species of Globochthonius . On balance, I think it is appropriate to transfer C. poeninus from Ephippiochthonius to the subgenus Globochthonius .

The redescription of adults of C. poeninus given above incorporates those of Mahnert (1979) and DeVore- Scribante (1999); the male has been drawn by Mahnert (1979) and further morphometric data are given by Muster et al. (2008).

Figures

FIGURES 276 – 281. Chthonius (E.) poeninus Mahnert, 1979. 276, female (Tessin, Val Pontirone), anterior margin of carapace; 277, id., anterolateral portion of carapace; 278, id., right chelicera; 279, id., right chela, lateral view; 280, male (Tessin, Val Carecchio), tip of fixed chelal finger, dorsal view; 281, tritonymph (Bavaria, Allgau Alps), id.