Chthonius (C.) pusillus Beier, 1947

Gardini, Giulio, 2014, The species of the Chthonius heterodactylus group (Arachnida, Pseudoscorpiones, Chthoniidae) from the eastern Alps and the Carpathians, Zootaxa 3887 (2), pp. 101-137 : 122-124

Chthonius (C.) pusillus Beier, 1947

( Figs 50–58 , 90 )

Chthonius (C.) pusillus Beier 1947: 298 , fig. 2.

Type locality: Austria, Styria, Mitterdorf im Mürztal towards Veitsch (47°32′43″ N 15°30′ 17″E).

Distribution. Austria, Slovenia.

Diagnosis (♂♀). An eyed epigean Chthonius (Chthonius) from the eastern Alps of Austria and Slovenia that differs from other species of the heterodactylus group in the following combination of characters: carapace without epistome, chaetotaxy m 4m:6:4:2:m 2m (22); chaetotaxy tergites I–IV: 4:4:4:4; genital opening of males flanked by aligned setae on each side; fixed chelal finger with 16–18 teeth with dental canals, usually without intercalary microdenticles, and with distal paraxial seta apically sinuous and weakly enlarged; movable chelal finger with 12–18 low, reclined teeth increasingly reduced towards finger base, reaching back almost to sb; coupled sensilla pc of movable chelal finger between trichobothria sb and b; chela length 0.67–0.81 (♂) or 0.75–0.79 (♀); movable finger length 0.42–0.50 (♂) or 0.45–0.48 (♀).

Material examined. AUSTRIA— Niederösterreich: 2 ♂ ( C. heterodactylus, M. Beier det.), Harzberg bei Bad Vöslau, Lindenwald, 22.X.1960 (collector not indicated) ( NHMW); 1 ♂, 3 ♀ (V. Mahnert det. 1978), Bezirk Scheibbs, Gaming , Kienberg-S-Hang , 13.XI.1978, F. Ressl leg., leaf litter ( MHNG). Steiermark: 2 ♂, 1 ♀ ( C. heterodactylus, M. Beier det.), Weberkogel zw. Birkfeld und Fischbach, 6.V.1967 (collector not indicated) ( NHMW); 10 ♂, 2 ♀ (V. Mahnert det. 1993), Bezirk Weiz, Raabklamm , 11.XII.1979 – 31.III.1980, P. Horak leg. ( MHNG); 4 ♂, 3 ♀ (V. Mahnert det. 1993), Bezirk Weiz, Weizklamm , 635/ 660 m a.s.l., 8.XI.1980 – 25.III.1981, P. Horak leg., Ostrya carpinifolia wood ( MHNG).

SLOVENIA — Podravska regija: 1 ♂, Maribor, Selnica ob Dravi, Šturmova graba Valley, artificial gallery in Šturmova graba, no. U3, 21.X.1977, V. Kuštor & T. Novak leg., trap ( PMSL).

Description of adults (♂♀). Carapace, tergites, chelicerae and pedipalps pale brown; hispid granulation on lateral surfaces of carapace, on cheliceral palm and on base of cheliceral movable finger. Carapace 0.95–1.05 times longer than broad, subquadrate, slightly constricted posteriorly; anterior margin ( Figs 50–52 ) usually without epistome, with thin, sharp denticles between median macrosetae; ocular area as in Fig. 53 , anterior eyes with convex lens (diameter 0.050–0.055 mm), posterior eyes with flat lens, both pairs with tapeta; distance from anterior eyes to anterior margin of carapace 0.030–0.040 mm; chaetotaxy m 4m:6:4:2:m 2m (22), macrosetae thick, rarely 2 preocular or 2 posterior microsetae on one side; posterior lateral microsetae very short, rarely half length of median macrosetae (1 ♂ from Austria, Raabklamm, 1 ♀ from Weizklamm; 1 ♂ from Slovenia, Selnica ob Dravi); length of anteromedian and anterolateral macrosetae respectively 0.095–0.115 and 0.075–0.090 mm, length of median macrosetae of ocular row 0.055–0.080 mm, length of posterior macrosetae 0.070–0.080 mm. Chaetotaxy of tergites I–X 4:4:4:4:6:6:6:6:6:4. Chaetotaxy of sternites II–X 10:(3)8–10(3):(2)7(2):8–9:6:6:6:6:7; genital opening of males flanked by 5–7 (usually 6) setae on each side [ 8 setae on each side according to Beier (1947)]. Chelicera ( Figs 54–55 ) 2.1–2.2 (♂) or 2.05–2.1 (♀) times as long as broad, palm with 6 setae and one microseta laterally; fixed finger with 9–13 teeth, the two distal teeth larger; movable finger with a large isolated subapical tooth (di) and 5–9 (usually 7) teeth decreasing in size proximally; gl ratio 0.52–0.60; spinneret weakly prominent in males, prominent and apically rounded in females; 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 4 + 3 marginal microsetae, II 4, III 5 (rarely 4), IV 6; coxa II with 6–11 (usually 10–11) coxal spines, coxa III with 4–6 (usually 4) coxal spines; intercoxal tubercle bisetose. Pedipalp: femur 4.6–5.4 (♂) or 4.8–5.1 (♀) times as long as broad; chela ( Figs 56–58 ) 4.8–5.2 (♂) or 4.5–4.8 (♀) times as long as deep [4.3–4.4 as long as deep (♂♀) in Beier (1947)]; hand of chela 1.6–1.8 (♂) or 1.55–1.65 (♀) times as long as deep [1.5 times as long as deep (♂♀) in Beier (1947)], weakly depressed behind ib/isb; fixed chelal finger sigmoid in lateral view, with 16–18 teeth [ 20–22 in Beier (1947)] with dental canals, usually without intercalary microdenticles (spaces between successive distal teeth undulated); reduced distal tooth at level of trichobothria dx/et; 10–14 large, sharp, reclined teeth increasing in size as far as halfway along the finger, then reduced in size towards the base; 4–7 proximal teeth low [8–10 in Beier (1947), 8–9 in Beier (1963)], with rounded tips; base of fixed finger with 4–5 microtubercles; fixed finger at level of it/est with 3–4 teeth occupying 0.1 mm (distance between successive apices 0.026–0.036 mm); tip of fixed finger with apical sensilla af1 ‾ 2, distal paraxial seta apically sinuous and weakly thickened; movable finger strongly curved in lateral view, with 12–18 low, reclined teeth, increasingly reduced towards finger base, reaching back almost to sb; proximal teeth between sb and b obsolete, revealed only by presence of dental canals; coupled sensilla pc usually nearer to sb than to b, rarely halfway between them; tip of movable finger with apical sensilla am1 ‾ 2; trichobothria as in Figs 56–58 , ist distad of the line eb/esb; ratio of movable finger/hand of chela 1.75–1.9 (♂) or 1.7–1.8 (♀); ratio of pedipalpal femur/movable finger 1.1–1.2 (♂♀); ratio of pedipalpal femur/carapace 1.15–1.4 (♂) or 1.2–1.25 (♀).

Measurements (in mm). Body length 1.2–1.4 (♂) or 1.3–1.6 (♀). Carapace 0.40–0.42 × 0.38–0.42 (0.33–0.37 anteriorly) (♂) or 0.42–0.45 × 0.42–0.44 (0.38–0.41 anteriorly) (♀). Chelicera 0.30–0.35 × 0.14–0.16 (♂) or 0.35–0.37 × 0.17–0.18 (♀); movable finger length 0.15–0.18 (♂) or 0.19–0.20 (♀). Pedipalp: femur 0.46–0.57 × 0.095–0.105 (♂) or 0.51–0.55 × 0.100–0.115 (♀); chela 0.67–0.81 × 0.14–0.17 (♂) or 0.75–0.79 × 0.16–0.18 (♀); hand length 0.230–0.285 (♂) or 0.265–0.285 (♀); fixed finger length (from tip to eb) 0.435–0.515 (♂) or 0.475–0.500 (♀); movable finger length 0.42–0.50 (♂) or 0.45–0.48 (♀).

Remarks. The above redescription of C. pusillus partially incorporates the original description of Beier (1947), which is nearly identical to that in Beier (1963), with the exception of the discrepancies noted above and the chaetotaxy of the posterior margin of the carapace [lateral setae of posterior row nearly as long as the median ones according to Beier (1947), as opposed to being very short microseta or, rarely, half the length of the median macrosetae].

Chthonius pusillus was previously known only from the Austrian states of Styria, Lower Austria and Carinthia ( Mahnert 2009, 2011). It is newly recorded here from Slovenia ( Fig. 90 ). Among the species of Chthonius of the C. heterodactylus group, the affinities of C. pusillus are uncertain. It can be distinguished from the other species using the key given above.

Figures

FIGURE 90. Distribution map for Chthonius (C.) cavernarum Ellingsen, 1909 (▲), C. (C.) heterodactylus Tömösváry, 1882 (Δ), C. (C.) hungaricus Mahnert, 1981 (■), C. (C.) lessiniensis Schawaller, 1982 (□), C. (C.) pusillus Beier, 1947 (●), C. (C.) raridentatus Hadži, 1930 (○).

FIGURES 50 – 58. Chthonius (C.) pusillus Beier, 1947. 50 – 52, Anterior margin of carapace of ♂ (Austria) (50), ♀ (Austria) (51) and ♂ (Slovenia) (52). 53, Anterolateral portion of carapace of ♂ (Austria). 54 – 55, Right chelicera of ♂ (54) and ♀ (55) (Austria). 56 – 58, Right chela, lateral view, of ♂ (Austria) (56), ♀ (Austria) (57) and ♂ (Slovenia) (58). Figures 50 – 51, 53 – 57: adults from Austria, Weizklamm; 52, 58: male from Slovenia, Šturmova graba.