Chthonius nicolosii, 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 : 105-108

Chthonius nicolosii n. sp.

( Figs 335–349 , 412 )

Chthonius (C.) ischnocheles ruffoi: Beier 1963a: 254 ; Lazzeroni 1969a: 322 (in part: Sicily).

Chthonius (C.) stammeri ruffoi: Beier 1963b: 33 (in part: Sicily).

Chthonius (C.) ruffoi: Gardini & Oggianu 1992: 24 (in part: Sicily).

Type locality: Italy, Sicily, Catania Province, Nicolosi, Grotta Lunga 1029 Si /CT (37°37’47”N, 15°02’04”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 (rarely 1) preocular microsetae; posterior margin of carapace with 4 macrosetae, lateral setae shorter than the median ones; chelicerae with 3 lateral microsetae; chela length 0.90–1.07 mm; movable chelal finger length 0.60–0.72 mm; chelal fingers with reclined, pointed, contiguous or less widely spaced teeth; fixed chelal finger with 52–64 teeth; fixed and movable chelal fingers at level of est -ist and st-t, respectively, with 7–9 and 6–8 teeth occupying 0.1 mm, distance between successive apices 0.011 –0.015 and 0.012 –0.016 mm respectively; ratio of pedipalpal femur/carapace 1.4–1.6.

Type material. ITALY — Sicily: 1 ♂ (holotype) 4 ♀ (paratypes), Catania Prov., Nicolosi, Grotta Lunga 1029 Si / CT (= Grotta di Monpeloso ), 850 m a.s.l., 18.X.1974, D. Caruso leg. ; 2 ♀ (paratypes), Catania, Grotta dei Roditori 234 Si /CT, 178 m a.s.l., 16.XII.2017, G. Nicolosi leg. ; 1 ♀ (paratype), San Gregorio di Catania, Grotta Immacolatella 1015 Si /CT, 9.IV.1975, D. Caruso leg. ; 1 ♀ (paratype), Zafferana Etnea, Grotta del Coniglio 17 Si /CT, V.1974, S. Brisolese leg. (holotype deposited in MHNG, paratypes in G. Gardini coll., Genoa) .

Derivatio nominis. Named after the naturalist and biospeleologist Dr Giuseppe Nicolosi (Dipartimento di Scienze della Vita e Biologia dei Sistemi, Università di Torino and Centro Speleologico Etneo, Catania), in recognition of his contribution to the knowledge of the subterranean fauna of Sicily.

Description of adults (♂ ♀). Integument slightly pigmented, carapace, tergites, chelicerae and pedipalps pale brown; weak hispid granulation on lateral surfaces of carapace, on cheliceral palm, on base of fixed chelal finger and dorsal surface of chelal hand. Carapace ( Fig. 337 ) 0.85–0.9 times longer than broad, trapezoidal, posteriorly constricted; anterior margin between median macrosetae with a prominent and sharp epistome in both sexes (figs 335–336); ocular area as in fig. 337, anterior eyes reduced, with flat lens (diameter 0.035 –0.040 mm), posterior eyes absent; distance from anterior eyes to anterior margin of carapace 0.040 –0.045 mm; standard chaetotaxy mm 4mm:6:4:2:4(24), rarely anterior row m 4mm or m 4m; length of anteromedian macrosetae 0.135 –0.155 mm, lateral setae of posterior row shorter than the median ones. Chaetotaxy of tergites 4:4:4:4:6:6:6:6:1T2T1:4:1T2T1:0. Chaetotaxy of sternites 10:(3)8–10(3):(2)7–8(2):8:6:6:6:6:2T1T2:0:2; genital opening of male flanked by 7 setae on each side. Chelicerae ( Fig. 338 ) 2.2 (♂) or 2.0–2.15 (♀) times as long as broad, palm with 6 setae and 3 lateral microsetae; fixed finger with 2 distal large teeth followed by 9–10 smaller teeth; movable finger with an isolated subapical tooth (di) at level with the spinneret, followed by a large tooth and 5–8 teeth proximally reduced in size; gs ratio 0.56–0.62 (♀ from Grotta del Coniglio with two setae gs on left chelicera); spinneret weakly raised in both sexes ( Figs 338–339 ); rallum with 11 blades; serrula exterior with 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 9–13 coxal spines, coxa III with 5–6 coxal spines; intercoxal tubercle with 2 microsetae. Pedipalp: femur 5.0–5.7 (♂ ♀) times as long as broad, femoral chaetotaxy 3:6:2:5:1; chela ( Figs 342, 346 ) 6.0 (♂) or 5.2–5.5 (♀) times as long as deep; hand of chela 2.0 (♂) or 1.8–1.9 (♀) times as long as deep, hand of male with almost parallel sides in dorsal view, slightly conical in females ( Figs 340–341 ); fixed chelal finger with 52–64 contiguous (♂) or less widely spaced teeth (♀) inclined backwards, all cuspidate except the proximal ones (about 5–10), which are apically rounded ( Figs 343–345, 347–349 ); all teeth with dental canal; base of fixed chelal finger with about 3 microtubercles; fixed finger at level of est-it with 7–9 teeth occupying 0.1 mm, distance between successive apices 0.011 –0.015 mm; tip of fixed chelal finger with apical sensilla af 1- 2, distal paraxial seta gradually curved and thin; movable chelal finger with 47–53 more widely spaced teeth, reclined and apically pointed in the distal third of the finger, apically rounded and increasingly reduced towards finger base, reaching back near b (between sb and b they are mainly recognizable only by the presence of dental canal) ( Figs 343–345, 347–349 ); movable finger at level of st-t with 6–8 teeth occupying 0.1 mm, distance between successive apices 0.012 –0.016 mm; coupled sensilla pc just distad of sb; tip of movable chelal finger with apical sensilla am 1- 2; trichobothria as in fig. 342, 346; ratio sb -st/sb -b = 1.7–2.0; ratio of movable finger/hand of chela 1.9–2.0 (♂ ♀); ratio of pedipalpal femur/movable finger 1.0–1.1 (♂ ♀); ratio of pedipalpal femur/carapace 1.4–1.6 (♂ ♀).

Measurements (in mm). Body length 1.5 (♂) or 1.6–1.8 (♀). Carapace 0.43 × 0.475 (0.46 anteriorly) (♂) or 0.47–0.51 × 0.51–0.57 (0.49–0.55 anteriorly) (♀). Chelicerae 0.435 × 0.195 (♂) or 0.49–0.555 × 0.23–0.27 (♀); movable finger length 0.23 (♂) or 0.27–0.295 (♀). Pedipalp: femur 0.60 × 0.115 (♂) or 0.675–0.80 × 0.125–0.14 (♀); chela 0.90 × 0.15 (♂) or 0.98–1.07 × 0.18–0.20 (♀); hand length 0.305 (♂) or 0.34–0.36 (♀); movable finger length 0.60 (♂) or 0.65–0.72 (♀).

Remarks. Specimens of Chthonius from the lava caves near Catania (Sicily) have been attributed in the past to C. ruffoi , species described from the cave Zinzulusa (Apulia) ( Beier 1963a, 1963b; Lazzeroni 1969a). Gardini & Oggianu (1992) redescribed C. ruffoi on specimens of both sexes from the type locality and attributed to this species the specimens of Sicilian lava caves, highlighting however their differences with specimens of the type locality of C. ruffoi . Following re-examination of these specimens, the Sicilian ones are recognized here as a new species. The specimens of C. nicolosii n. sp. were collected in lava caves that formed as a result of eruptions of the Etna volcano some 15,000 years ago until the 17 th century CE ( Branca et al. 2011).

Chthonius nicolosii is a species of recent hypogean origins and uncertain taxonomic affinities: its chelal tooth pattern is intermediate between that of C. densedentatus and that of the C. multidentatus - gallettii group. With all these species, C. nicolosii shares the presence of 1 or 2 preocular microsetae and 3 lateral microsetae on the cheliceral palm, while it does not have lateral microsetae on the posterior margin of the carapace. Instead it has 4 macrosetae of which the two lateral ones can be as long as the median, or up to a third of the median ones. The main differences among these species are summarized in the Key to species.

A record of Chthonius ischnocheles ruffoi from Chiusazza cave near Syracuse ( Beier, 1963a) is of uncertain affinities, but almost certainly does not to refer to C. nicolosii .

Figures

FIGURES 335–341. Chthonius nicolosii n. sp., Grotta Lunga (Nicolosi, Catania). 335, male holotype, anterior margin of carapace; 336, female paratype, id.; 337, male holotype, carapace; 338, male holotype, right chelicera; 339, female paratype, movable finger of right chelicera; 340, male holotype, right chelal hand, dorsal view; 341, female paratype, id.

FIGURES 342–349. Chthonius nicolosii n. sp., Grotta Lunga (Nicolosi, Catania). 342, male holotype, right chela, antiaxial view; 343, male holotype, detail of fingers at the chelal tip, antiaxial view; 344, male holotype, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 345, male holotype, detail of fingers at level of trichobothrium sb, antiaxial view; 346, female paratype, right chela, antiaxial view; 347, female paratype, detail of fingers at the chelal tip, antiaxial view; 348, female paratype, detail of fingers at level of trichobothria est-it and st-t, antiaxial view; 349, female paratype, 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.