Roncus aetnensis Gardini & Rizzerio, 1987

(Figs 29–38, 114)

Roncus aetnensis Gardini & Rizzerio, 1987: 74, figs 12–17.

Type locality: Italy, Sicily, Catania Province, Catania, Grotta Nuovalucello I 1008 Si/CT (37°31’47”N 15°05’22”E).

Distribution. Italy (Sicily).

Diagnosis (♂ ♀). A large subterranean Roncus that differs from other Sicilian species of the genus in the following combination of characters: carapace with equilateral epistome, posterior border with 6 setae, eyes with weakly convex lens or reduced to ocular spot; tergite I mostly with 6 (rarely 5) setae; cheliceral palm with 6 setae; pedipalpal femur and chelal hand with weakly granular surface, patella nearly smooth; pedipalpal femur 1.38–1.85 mm length (4.76–5.34 ×), without tubercles on the paraxial face; patella 1.13–1.54 mm (2.98–3.45 ×), club/pedicel ratio = 1.5–1.7; chelal hand without microsetae proximal to trichobothrium eb and 3–5 microsetae between the trichobothria eb and esb; fixed chelal finger with trichobothrium isb at the same distance from both ist and ib; fixed and movable chelal fingers with 87–106 and 82–98 teeth, respectively; 26–29 teeth between the trichobothrium t and the apex of the movable chelal finger; movable chelal finger 1.37–1.71 mm length; ratio of movable chelal finger/hand of chela with pedicel 1.06–1.28; ratio of pedipalpal femur/movable chelal finger 0.98–1.11; ratio of pedipalpal femur/carapace 1.18–1.51.

Type material examined. ITALY — Sicily: Catania Prov: 1♀ holotype, 1♂ 1♀ paratypes labelled “ Sicilia, Catania, Grotta Nuovalucello I n. 8 Si/CT, 26.XI.1974, D. Caruso leg.”; 1♀ paratype, same data but 24.I.1974; 2♀ paratypes labelled “ Sicilia, Catania, S. Giovanni Galermo, Grotta di Marrano n. 28 Si/CT, 21.II.1975, D. Caruso leg. (Coll. G. Gardini, Genoa).

Non-type material examined. ITALY — Sicily: Catania Prov.: 1D, Acicastello, Grotta di Zappalà 140 Si /CT, 24.III.1974, D. Caruso leg.; 1♀, Adrano, Grotta di Monte Intralio 1007 Si /CT, 1370 m a.s.l., 20.I. 2022, G. Nicolosi leg.; 1♂, id., 6.VII.2022, G. Nicolosi leg.; 1♂ 3♀, Adrano, Grotta di San Nicola (= del Santo) 1032 Si/CT, 1041 m a.s.l., 18.VI.2021, G. Nicolosi leg.; 2♂ 1♀, id., 2.VIII.2022, G. Nicolosi leg.; 1♂ 1♀ 1T, id., 20.XI.2022, G. Nicolosi leg.; 1♂ 3♀, Belpasso, Grotta Ampudda di Pisciteddu 146 Si/CT, 615 m a.s.l., 23.VI.2021, G. Nicolosi leg.; 1♂, id., 21.VII.2022, G. Nicolosi leg.; 1♀, Belpasso, Grotta Mezzasciara n.c. Si/CT, 776 m a.s.l., 21.VII.2022, G. Nicolosi leg.; 1♀, Castiglione di Sicilia, Grotta di Monte Crisimo 170 Si/CT, 1348 m a.s.l., 22.VII.2022, G. Nicolosi leg.; 1♀, id., Grotta di Monte Dolce 110 Si /CT, 847 m a.s.l., 13.VIII.2022, G. Nicolosi leg.; 1T, id., Grotta di Monte Corruccio 1056 Si /CT, 1389 m a.s.l., 28.VIII.2020, G. Nicolosi leg.; 1T, Catania, Grotta dei Roditori 234 Si /CT, 178 m a.s.l., 16.XII.2017, G. Nicolosi leg.; 1♂, Catania, San Gioanni Galermo, Grotta Manganelli n.c. Si /CT, 303 m a.s.l., 22.IV.2019, G. Nicolosi leg.; 2♀, Linguaglossa, Grotta dei Rotoli 1239 Si/CT, 1488 m a.s.l., 20.VIII.2020, G. Nicolosi leg.; 1♀, id., 8.VI.2021, G. Nicolosi leg.; 1♂, id., 6.I.2022, G. Nicolosi leg.; 6♂ 6♀ 1T (remains), id., 13.VIII.2022, G. Nicolosi leg.; 2♀, Linguaglossa, Grotta del Porcospino 1033 Si /CT, 982 m a.s.l., 28.VII.2021, G. Nicolosi leg.; 1♀, id., 29.VII.2021, G. Nicolosi leg.; 1♀, id., 13.VIII.2022, G. Nicolosi leg.; 1♀, Linguaglossa, Grotta di Piano Porcaia 101 Si /CT, 1110 m a.s.l., 28.VII.2001, G. Nicolosi leg.; 1♀, id., 5.VI.2018, G. Nicolosi leg.; 1♀, id., 14.VIII.2022, G. Nicolosi leg.; 3♂ 2♀ 1T, Mascali, Grotta Forcato 1013 Si/CT, 670 m a.s.l., 28.VIII.2020, G. Nicolosi leg.; 1♂ 2♀ 1T (remains), id., 23.XII.2020, G. Nicolosi leg.; 5♂ 7♀ 1T, id., 1.VIII.2021, G. Nicolosi leg.; 2♂ 1♀, id., 21.I.2022, G. Nicolosi leg.; 1♂ 1♀, id., 13.VIII.2022, G. Nicolosi leg.; 1♀ 1T, Milo, Grotta Serracozzo 1065 Si /CT, 1840 m a.s.l., 30.XII.2020, G. Nicolosi leg.; 1♂ 1♀ (remains), Milo, Mount Etna slope, 9.VII.2020, G. Nicolosi leg. in MSS; 1♀, id., 30.XI.2020, G. Nicolosi leg. in MSS; 1♂, Nicolosi, Grotta Lunga (= Grotta di Monpeloso) 1029 Si/CT, 820 m a.s.l., 20.XI.2016, G. Nicolosi leg.; 3♂ 5♀, id., 16.VI.2021, G. Nicolosi leg.; 6♂ 10♀, id., 21.VII.2022, G. Nicolosi leg.; 3♀, Randazzo, Grotta delle Femmine 1046 Si /CT, 1610 m a.s.l., 3.VIII.2021, G. Nicolosi leg.; 1♀, id., 10.VIII.2022, G. Nicolosi leg.; 2♂ 3♀, Trecastagni, Grotta di Monte Cicirello 1156 Si/CT, 990 m a.s.l., 29.XII.2020, G. Nicolosi leg.; 1T, id., 10.VI.2021, G. Nicolosi leg.; 3♀, id., 14.I.2022, G. Nicolosi leg.; 2♂, id., 21.VII.2022, G. Nicolosi leg.; 1♀, Zafferana Etnea, Grotta di Monte Arcimis 1031 Si/CT, 1164 m a.s.l., 31.VI.2021, G. Nicolosi leg. Sicily: Messina Prov.: 1♂ 2♀, Monti Nebrodi, San Fratello, Passo dei Tre, 800 m a.s.l., VI.2018, P. Magrini leg. Sicily: Palermo Prov.: 2♂ 2♀ 1T 1D, Cefalù, Abisso del Gatto 245 Si/PA, 380 m a.s.l., 10.VI.2017, G. Nicolosi leg.

Description of adults (♂ ♀). Carapace, chelicerae, pedipalps and palpal coxae red-brown; pedipalpal femur and chelal hand with weakly granular surface, patella nearly smooth, pleural membrane granulate. Carapace 1.29–1.62 (♂ ♀) times as long as broad, anterior margin with equilateral epistome apically blunt (0.04–0.07 mm length); two weak eyes with a slightly convex lens (Fig. 29) or reduced to ocular spots; anterior lateral process acute, slightly prominent; subbasal transverse furrow present; standard chaetotaxy 4:8:6:6 (rarely anterior row with 5 setae, ocular row with 9, median row with 7 and posterior row with 7 setae), subocular setae absent. Chaetotaxy of tergites I–X (♂ ♀): 6–7:6–9:8–10:9–11:10–11:10–11:10–11:10–11:10–11:8–9 (probable standard chaetotaxy: 6:6:10:11:11:11:1 1:11:11:9). Chaetotaxy of sternites II–X (♂): 21–27:(3)10–17(3):(3)9–12(3):12:12:12:12:12:11, lateral genital sacs tubular, median genital sac pear-shaped, reaching the base of sternite IV, genital atrium with 2+2 (rarely 2+3 setae); anterior and posterior margin of genital opening with 9–13 and 6–7 setae, respectively; chaetotaxy of sternites II–X (♀): 9–15:(3)12–17(3):(3)9–10(3):11–13:12–15:12–15:12–14:11–13:10–12, sternite III–IV rarely with 4 setae on stigmata. Chelicera (Fig. 30) 1.94–2.13 (♂ ♀) times as long as broad, palm with 6 setae (rarely the same specimen with 5 and 6 or 6 and 7 setae); fixed finger with 10–18 pointed and spaced teeth, plus some distal teeth that are small, contiguous and flat; movable finger with 10–15 teeth, the largest just distad gs; gs ratio 0.67–0.72, spinneret barely noticeable in both sexes; rallum with one short proximal blade and 7 (rarely 6) longer blades, all blades anteriorly combed, also the first, which is apparently smooth; serrulae interior and exterior with 26 and 38–40 blades, respectively. Manducatory process with 4 setae. Coxal setae (♂ ♀): pedipalp 7–10, I 6–8, II 6–8, III 5 (rarely 6), IV 7–9 (probable standard chaetotaxy: 8:7:7:5:8); anterolateral process of coxa I stubby and pointed, anteromedial process not prominent, rounded (Fig. 31). Pedipalp (Figs 32, 34–38): trochanter weakly granular dorsally, 2.56–2.89 (♂ ♀) times as long as broad, with three small tubercles with lyrifissure on antiaxial face; femur 5.16–5.34 (♂) or 4.76–5.27 (♀) times as long as broad, gradually enlarged in the basal third, subparallel in the two distal thirds, with one tubercle proximally the half of the antiaxial face, 1–2 weak dorso-distal tubercles with glandular pore, tubercles on the paraxial face absent, granulation as in figs 32, 36; patella 3.19–3.45 (♂) or 2.98–3.33 (♀) times as long as broad, with one weak dorso-distal tubercle with glandular pore and 1–3 micropore at base of dorsal face of pedicel; club/pedicel ratio of patella (♂ ♀) = 1.5–1.7; chela with pedicel 4.31–4.82 (♂) or 3.77–4.25 (♀) times as long as broad; hand of chela with pedicel 2.00–2.27 (♂) or 1.90–2.09 (♀) times as long as broad, with oval profile and its greatest width in the proximal third (dorsal view), granulation as in figs 34–35, 37–38; chelal hand with a tubercle with a glandular pore on the antiaxial face close to the movable finger base and one micropore at base of dorsal face of pedicel; 3–5 microsetae between the trichobothria eb and esb (microsetae proximal eb absent) (Figs 35–38); fixed chelal finger with 93–98 (♂) or 87–106 (♀) contiguous and weakly pointed teeth; nodus ramosus subterminal; movable chelal finger with 83–89 (♂) or 82–98 (♀) teeth (5–6 teeth occupying 0.1 mm) with flat apex, apart from the distals which are pointed (Figs 35, 38); 26–29 teeth between the trichobothrium t and the apex of the movable finger; marginal sensillum at the level or distal the trichobothrium sb (rarely proximal sb); all teeth with dental canals; trichobothria as in figs 34–35, 37–38, relative position of trichobothria along chelal axis (♂ ♀): et 0.13–0.14/ it 0.175–0.20/ est 0.245 –0.28/ ist 0.45–0.50/ isb 0.64–0.675/ ib 0.77–0.86/ esb 0.83–0.89/ eb 0.90–0.93/ t 0.19–0.23/ st 0.32–0.38/ sb 0.58–0.63/ b 0.84–0.88; trichobothrium isb halfway between ib and ist, trichobothrium est halfway between t and st; ratio of movable chelal finger/hand of chela with pedicel 1.11–1.28 (♂) or 1.06–1.22 (♀); ratio of pedipalpal femur/movable finger 0.98–1.09 (♂) or 1.04–1.11 (♀); ratio of pedipalpal femur/carapace 1.23–1.42 (♂) or 1.18–1.51 (♀). Leg IV (Fig. 33): trochanter 2.39–2.50 (♂ ♀) times as long as deep, femur + patella 3.57–4.56 (♂ ♀) times as long as deep, tibia 6.55–8.72 (♂ ♀) times (TS = 0.51–0.59), basitarsus 3.33–4.36 (♂ ♀) times (TS = 0.15–0.22), telotarsus 5.18–6.67 (♂ ♀) times as long as deep (TS = 0.32–0.45), ratio of basitarsus/telotarsus 0.66– 0.76 (♂ ♀), subterminal seta furcate, claws with dorsal tooth.

Measurements. Body length 3.8–5.8 (♂ ♀). Carapace 1.04–1.20 × 0.77–0.80 anteriorly (♂) or 1.08–1.34 × 0.76–0.91 anteriorly (♀). Chelicera 0.65–0.76 × 0.32–0.385 (♂) or 0.71–0.87 × 0.35–0.42 (♀); movable finger length 0.44–0.51 (♂) or 0.48–0.60 (♀). Pedipalp: trochanter 0.75–0.94 × 0.285–0.33 (♂) or 0.80–1.12 × 0.295–0.39 (♀); femur 1.38–1.71 × 0.265–0.32 (♂) or 1.425–1.85 × 0.27–0.38 (♀); patella 1.13–1.45 × 0.335–0.42 (♂) or 1.15–1.54 × 0.36–0.50 (♀); chela with pedicel 2.34–2.80 × 0.485–0.65 (♂) or 2.35–3.00 × 0.575 –0.795 (♀); hand with pedicel length 1.10–1.41 (♂) or 1.15–1.59 (♀); movable finger length 1.37–1.57 (♂) or 1.37–1.71 (♀). Leg IV: trochanter 0.50–0.66 × 0.22–0.27 (♂ ♀); femur + patella 1.25–1.50 × 0.29–0.35 (♂) or 1.25–1.62 × 0.30–0.40 (♀); tibia 1.17–1.45 × 0.16–0.18 (♂) or 1.17–1.62 × 0.15–0.21 (♀); basitarsus 0.44–0.54 × 0.12–0.14 (♂) or 0.44–0.61 × 0.125–0.16 (♀); telotarsus 0.625–0.80 × 0.11–0.12 (♂) or 0.64–0.815 × 0.11–0.14 (♀).

Description of tritonymph. Carapace, chelicerae, pedipalps and palpal coxae red-brown pale; pedipalpal femur and chelal hand with weakly granular surface, patella smooth, pleural membrane granulate. Carapace 1.43–1.67 times as long as broad, eyes reduced to ocular spots, rarely with a flat lens; anterior margin with broad epistome apically rounded; chaetotaxy 4:8:6:6 (rarely 4:8:8:6). Chaetotaxy of tergites I–X: 6:6:8–9:8–10:11:11:11:11:11:9. Chaetotaxy of sternites II–X: 3:(2)7–8(2):(2)7–8(2):10–13:11–13:13:13:13:11–12. Chelicera 1.92–2.02 times as long as broad, palm with 6 setae; fixed finger with 11–12 pointed and spaced teeth, and 5-6 distal teeth that are small, contiguous and flat; movable finger with 10–12 teeth, the largest just distad gs; gs ratio 0.70–0.75, spinneret just prominent and wide; rallum with one short proximal blade and 6 longer blades, all blades anteriorly combed, also the first, which is apparently smooth. Manducatory process with 3 setae. Coxal setae: pedipalp 7–8, I 6–7, II 5–6, III 5, IV 7; anterolateral process of coxa I stubby and pointed, anteromedial process not prominent, rounded. Pedipalp: trochanter 2.34–2.47 times as long as broad; femur weakly granulate, 4.27–4.72 times as long as broad, with one tubercle proximally the half of the antiaxial face, one weak dorso-distal tubercle with glandular pore, and without tubercles on the paraxial face; patella with smooth surface, 2.81–3.33 times as long as broad, with one weak dorso-distal tubercle with glandular pore and one or two micropores at base of dorsal face of pedicel; chela with pedicel 3.65–4.22 times as long as deep; hand of chela with pedicel 1.84–2.01 times as long as deep, weakly granulate, with 2–4 microsetae between the trichobothria eb and esb (microsetae proximal eb absent); fixed chelal finger with 63–74 contiguous and pointed teeth; nodus ramosus subterminal; movable chelal finger with 64–71 flat apex teeth, apart from the distals which are pointed; 27–30 teeth between the trichobothrium t and the apex of the movable finger; marginal sensillum at the level of the 6th–13th teeth proximal the trichobothrium st; all teeth with dental canals; relative position of trichobothria along chelal axis: et 0.17–0.185/ it 0.22–0.265/ est 0.30 –0.33/ ist 0.48–0.515/ ib 0.78–0.795/ esb 0.83–0.84/ eb 0.895–0.93/ t 0.285 –0.325 / st 0.52–0.56/ b 0.83–0.85; ratio of movable chelal finger/hand of chela with pedicel 1.12–1.26; ratio of pedipalpal femur/movable finger 0.99–1.07; ratio of pedipalpal femur and carapace 1.10–1.23. Leg IV: trochanter 2.02–2.18 times as long as deep, femur + patella 3.74– 4.14 times as long as deep, tibia 5.57–6.83 times (TS = 0.47–0.54), basitarsus 2.87–3.27 times (TS = 0.16–0.20), telotarsus 4.18–5.11 times as long as deep (TS = 0.32–0.38), ratio of basitarsus/telotarsus 0.60–0.64, subterminal seta furcate, claws with dorsal tooth.

Measurements. Body length 3.0–3.7. Carapace 0.80–0.93 × 0.53–0.65 anteriorly. Chelicera 0.48–0.595 × 0.25– 0.30; movable finger length 0.32–0.385. Pedipalp: trochanter 0.50–0.65 × 0.21–0.28; femur 0.94–1.15 × 0.20–0.265; patella 0.73–0.93 × 0.24–0.33; chela with pedicel 1.54–1.88 × 0.365 –0.515); hand with pedicel length 0.735–0.95; movable finger length 0.90–1.07. Leg IV: trochanter 0.33–0.415 × 0.155–0.19; femur + patella 0.83–1.03 × 0.21– 0.275; tibia 0.76–0.94 × 0.12–0.145; basitarsus 0.275 –0.345 × 0.09–0.12; telotarsus 0.46–0.54 × 0.09–0.11.

Remarks. Roncus aetnensis was described by Gardini & Rizzerio (1987) based on specimens of both sexes from the volcanic caves Grotta Nuovalucello I 1008 Si/CT and Grotta di Marrano 028 Si/CT, both near Catania, and was doubtfully attributed by them to the Hyblean-Maltese-Tunisian species of the Roncus siculus group (i.e., Roncus siculus, Roncus comasi, Roncus carusoi Gardini & Rizzerio, 1987 and Roncus melitensis). The species is widespread in the Etna area, occurring in many lava tubes, as in the MSS (Milo near Catania), and is also recorded from a cave in the Madonie Mts near Cefalù (Abisso del Gatto 245 Si/PA) and from endogean habitat from the Nebrodi Mountains (San Fratello).

Despite a notable degree of adaptive morphological modifications, Roncus aetnensis appears to be primarily associated with the MSS and to have colonized lava tubes from Etna relatively recently, as suggested by Gardini & Rizzerio (1987). Although Etna's subaerial eruptive activity dates back more than 200 ka, to the Middle Pleistocene, the lava flows that formed the lava tubes are likely much more recent, resulting from summit and side craters that occurred from 15 ka to the present during the last Etna effusive phase, known as the Mongibello volcanics (Branca et al. 2011; Mammino & Santonocito 2014).

Despite the affinities of Roncus aetnensis being uncertain, it shows strong morphological convergence with Roncus gallettiae sp. nov. from the cave Dolina di Galermi 6020 Si/RG near Ragusa (Iblean Plateau), from which it differs mainly in the different club/pedicel ratio of the pedipalpal patella [1.46–1.63 × (♂) or 1.52–1.77 × (♀) in Roncus aetnensis, 1.30 × (♂) or 1.38 × (♀) in Roncus gallettiae sp. nov.] and in the position on the fixed pedipalpal finger of the trichobothrium isb in relation to ist and ib (isb halfway between ist and ib in Roncus aetnensis, isb closer to ist than to ib in Roncus gallettiae sp. nov.).

The above redescription of Roncus aetnensis partially includes those of Gardini & Rizzerio (1987), and confirms, in all examined specimens, the absence of tubercles on the paraxial face of pedipalpal femur.