Neobisium (Neobisium) corsicum, Gardini, 2023

Gardini, Giulio, 2023, The troglomorphic pseudoscorpions of the genus Neobisium from Corsica, Sardinia and mainland Italy, with description of new species (Pseudoscorpiones: Neobisiidae), Zootaxa 5381 (1), pp. 1-67 : 7-9

Neobisium (Neobisium) corsicum n. sp.

( Figs 1–9 , 118 )

Neobisium (Ommatoblothrus) vandeli Beron, 1972 (nomen nudum).

Type locality: France, Corsica, Haute-Corse, Corte, commune de Casanova: Valletto, Grotte de Valletto (42°16’20.10”N 9°10’05.20”E) .

Distribution. France: Corsica.

Diagnosis (♀). A subterranean, highly troglomorphic Neobisium from Corsica that differs from other Mediterranean species of the genus in the following combination of characters: carapace without triangular epistome, posterior margin with 4 setae, preocular setae absent; anterior eyes barely visible, dark integument between anterior and posterior eyes absent; tergites I–IV: 4:4:4:4–5; cheliceral palm with 6 setae, rallum with 8 blades; manducatory process with 4 setae; fixed chelal finger homodentate, with contiguous teeth; fixed and movable chelal fingers with 141–146 and 117–122 teeth, respectively; spinneret almost absent; pedipalpal femur 2.40–2.60 mm length (9.28–9.60 ×), patella 2.06–2.15 mm (6.64–6.72 ×), movable finger 2.45–2.48 mm; pedipalpal hand with a long oval profile and its greatest width in the middle, chela with the same curvature both in dorsal and lateral view; ratio between movable chelal finger and hand of chela with pedicel 1.71–1.77; ratio between pedipalpal femur and movable chelal finger 0.98–1.04; ratio between pedipalpal femur and carapace 2.60; trichobothrium ist just distal to st, closer to the finger tip than to isb.

Type material. FRANCE — Corsica: Holotype ♀, Haute-Corse, Corte, commune de Casanova, Valletto, Grotte de Valletto (42°16’20.10”N 9°10’05.20”E), 696 m a.s.l., 14.VII.2019, Ligue Insulaire Spéléologique Corse leg. ( MNHN) . Paratype: 1♀, Haute-Corse, Calvi, commune de Sorio, Grotta de Gudrone (42°35’10.00”N 9°16’05.99”E), 351 m a.s.l., 21.VII.2019, Ligue Insulaire Spéléologique Corse leg. ( MNHN) .

Derivatio nominis. The Latin adjective corsicus (-a, -um) means belonging to, or related to, the Mediterranean island Corsica.

Description (♀; ♂ unknown) (data concerning the female paratype in brackets). Carapace, chelicerae, pedipalps and palpal coxae brown pale; pedipalps smooth, pleural membrane granular. Carapace 1.43 times as long as broad, with four hardly noticeable eyes, without tapetum, the anterior ones more visible, the posterior ones reduced to a faint white spot; anterior margin without epistome, slightly prominent in the middle ( Fig. 1 ); chaetotaxy 4–6–6–4, without preocular setae. Chaetotaxy of tergites I–X: 4:4:4:4(5):4:6:6:6:6:7. Chaetotaxy of sternites II–X: 9(12):18 (19):12(10):8:8:8(9):8:8:7(8); sternites III and IV with 3 and 2 microsetae in front on each stigma, respectively. Chelicera ( Figs 2–3 ) 2.0(1.94) times as long as broad, palm with 6 setae; fixed finger with about 8 worn teeth; movable finger with worn teeth, of which one or two larger distally gs; gs ratio 0.65(0.64), spinneret almost absent; rallum with 8 blades, the three distal laterally serrate, the successive ones smooth, the proximal one very short; serrulae interior and exterior with about 30 and 35 blades, respectively. Manducatory process with 3–4(4–4) setae. Coxal setae: pedipalp 7, I 4 and 5(5), II 5, III 4 and 5(4), IV 6; anterolateral process of coxa I squat, anteromedial process without spicules ( Fig. 4 ). Pedipalp ( Figs 5–8 ): trochanter 2.85(2.92) times as long as broad, on antiaxial face with 3 weak button-like tubercles (with lyrifissure); femur 9.28(9.60) times as long as broad, weakly enlarged distally; patella 6.72(6.64) times as long as broad, club gradually enlarged distally, ratio between club and pedicel 3.1(2.8), ratio X/Y = 0.18(0.18), base of pedicel dorsally with two glandular pores; chela with pedicel 8.15(8.13) times as long as broad, with the same curvature both in dorsal and lateral view; hand of chela with pedicel 3.04(3.17) times as long as broad, with a long oval profile and its greatest width in the middle (dorsal view), base of pedicel dorsally with 7 glandular pores; fixed chelal finger regularly homodentate, with 146(141) pointed contiguous teeth ( Figs 7–8 ); nodus ramosus subterminal; movable chelal finger with 122(117) flattened contiguous teeth, apart from the distal ones (distally the trichobothrium st) which are cuspidate ( Figs 7–8 ); all teeth with dental canals; sensillum not seen (13 teeth proximally trichobothrium st in female paratype); trichobothria as in figs 6–7, relative position of trichobothria along chelal axis: it 0.11(0.18)/ et 0.125(0.135)/ est 0.175 (0.20)/ ist 0.36(0.34)/ isb 0.80(0.75)/ ib 0.96(0.92)/ esb 0.99(0.96)/ eb 1.0(0.98)/ t 0.18(0.18)/ st 0.39(0.39)/ sb 0.71(0.66)/ b 0.91(0.88); trichobothrium est just distal t (just proximal t); trichobothrium ist distal st, closer to the finger tip than to isb; trichobothrium isb proximal sb; ratio between movable chelal finger and hand of chela with pedicel 1.77(1.71); ratio between pedipalpal femur and movable chelal finger 1.04(0.98); ratio between pedipalpal femur and carapace 2.6. Leg IV ( Fig. 9 ) (slightly deformed by compression in the female paratype): trochanter 3.16(3.26) times as long as deep, femur + patella 7.45(6.58) times as long as deep, tibia 14.07(10.85) times [TS = 0.23(0.26)], basitarsus 7.72(7.16) times [TS = 0.095(0.090)], telotarsus 13.33(?) times as long as deep [TS = 0.48(0.52)], ratio between basitarsus and telotarsus 0.71(0.79), subterminal seta furcate, claws with evident dorsal tooth.

Measurements. Body length 3.7. Carapace 1.0 × 0.70 anteriorly. Chelicera 0.74(0.70) × 0.37(0.36); movable finger length 0.47(0.46). Pedipalp: trochanter 0.80(0.79) × 0.28(0.27); femur 2.60(2.40) × 0.28(0.25); patella 2.15(2.06) × 0.32(0.31); chela with pedicel 3.75(3.66) × 0.46(0.45); hand with pedicel length 1.40(1.43); movable finger length 2.48(2.45). Leg IV: trochanter 0.76(0.75) × 0.24(0.23); femur + patella 2.16(2.14) × 0.29(0.325?); tibia 1.97(1.90) × 0.14(0.175?); basitarsus 0.85(0.86) × 0.11(0.12); telotarsus 1.20(1.08) × 0.09(0.11).

Remarks. The presence of a highly specialized subterranean Neobisium in Corsica had already been known for some time. Beron (1972) in fact cited Neobisium (Ommatoblothrus) vandeli (nomen nudum) from the Grotte de Manuel-Ange C25 (Punta di Orchinu, north of Cargèse, 42°10’N 8°33’E). There can be no certainty in conspecificity between the specimens of N. corsicum n. sp. and the specimen cited by Beron (1972), as the latter has not been examined for this study. However, I consider the conspecificity to be probable, despite the Cargèse karstic area being separated from those of the caves of Valletto and Gudrone―the localities of N. corsicum n. sp. ―50 and 70 km respectively, all in karst complexes independent from each other.

The affinities of Neobisium corsicum n. sp. are uncertain. However, the new species can be compared to N. gracile Heurtault, 1979 from mainland France (Hérault, Brissac, Abîme de Rabanel), a subterranean species with similar but less marked adaptive morphological features. The two species share the same number of setae in the posterior margin of carapace, in tergites I-II, in maxillary process and in cheliceral hand, the same structure of the rallum, the same pattern of dentition of pedipalpal fingers and the same pedipalpal shape. Compared to Neobisium gracile , N. corsicum n. sp. is larger in size (length of pedipalpal femur 2.40–2.60 mm in N. corsicum , 2.15 mm in N. gracile ; pedipalpal patella 2.06–2.15 mm in N. corsicum , 1.70 mm in N. gracile ; chela 3.66–3.75 mm in N. corsicum , 3.30 mm in N. gracile ), has more slender appendages (pedipalpal femur 9.28–9.60 times as long as broad in N. corsicum , 8.27 times as long as broad in N. gracile ; pedipalpal patella 6.64–6.72 times as long as broad in N. corsicum , 5.66 times as long as broad in N. gracile ; chela 8.13–8.15 times as long as broad in N. corsicum , 0.76 times as long as broad in N. gracile ) and has a greater number of teeth at the pedipalpal fingers (fixed and movable chelal fingers with 141–146 and 117–122 teeth, respectively, in N. corsicum , with 130 and 107 teeth, respectively, in N. gracile ).

Figures

FIGURE 118. Map depicting known distribution of Neobisum species with troglomorphic facies from Sardinia (A), Ligurian Alps and Corsica (B).

FIGURES 1–9. Neobisium (N.) corsicum n. sp., female holotype, Grotte de Valletto (Corte, Corsica) (unless otherwise stated). 1, anterior margin of carapace; 2, right chelicera, dorsal view; 3, female paratype, Grotta de Gudrone (Sorio, Corsica), movable cheliceral finger of left chelicera, dorsal view; 4, anterior processes of right coxa I; 5, trochanter, femur and patella of right pedipalp, dorsal view; 6, right pedipalpal chela, dorsal view; 7, same, antiaxial view; 8, detail of teeth at level of trichobothria est and t, antiaxial view; 9, right leg IV, antiaxial view.