Arcanobisium comasi, Zaragoza, Juan A., 2010

Zaragoza, Juan A., 2010, Arcanobisium, a remarkable new genus, representing a new subfamily with a relictual distribution from eastern Spain (Arachnida: Pseudoscorpiones: Syarinidae), Zootaxa 2491, pp. 41-60 : 44-48

Arcanobisium comasi sp. nov.

( Figs 2–25 )

Type material. Male holotype: Spain, Valencian Community, Castellón province, La Plana Alta, Cabanes, Avenc d’en Serenge, UTM coordinates: 31TBE501469, altitude 305 m, 14 March 1982, collected by Jordi Comas, deposited in MCNB: register number: 2009 - 4118 MZB.

Etymology. The species is named after the biospeleologist Jordi Comas, from Barcelona, who collected the unique specimen and to honour his work collecting and studying cave-dwelling arthropods for the past 40 years.

Description. A small pseudoscorpion (body length 1.64 mm); legs pale, carapace, opisthosomal segments and pedipalps pale brown in colour and showing in general a weak polygonal or scaly reticulation.

Carapace ( Fig. 4 ). Elongated, maximum width at posterior margin. Without eyes or eye-spots. Epistome small and rounded ( Fig. 5 ). Chaetotaxy: 21 setae, formula: 4:4:4:3:6. Two glandular pores on each side of the anterior third. Three microlyrifissures on the anterior zone.

Coxal area ( Fig. 19 ). Apex of pedipalpal coxa triangular, long and acute, with 2 distal setae. Pedipalpal coxa with 7–8 setae, pedal coxa I: 5, II: 4, III: 3, IV: 4. Anterolateral process of coxa I rounded and moderately prominent, with some granules at the apex; medial process absent.

Opisthosoma. Ovate ( Figs 2–3 ), pleural membrane laterally striate and medially weakly granulated ( Fig. 25 ). Tergite I longer than other tergites. Only tergites and sternites I–IX visible dorsally and ventrally, respectively ( Figs 2–3 , 23–25 ): tergal and sternal plates X–XI extremely reduced in size, difficult to recognize and only distinctly visible laterally or ventrally ( Figs 23–25 ); tergite XI limited to a narrow band without setae, sternite XI divided into two lateral isolated diminutive plates, each bearing one seta. Sternites IV and V distinctly wider than the others. Tergal chaetotaxy I–XI: 8: 8: 10: 8: 8: 8: 7: 6: 6: 4: 0. Anal cone with 2 ventral and 2 dorsal setae. Genital area with 11 setae on sternite II plus 13 small setae on the anterior genital opening; sternite III with 11 setae, both medial setae thickened, 3 small setae on anterior margin ( Fig. 20 ); genitalia with 3+3 internal setae ( Fig. 21 ). Chaetotaxy of sternites IV–XI: 8: 9: 11: 11: 11: 6: 5: 2. One microseta in front of each stigma of sternite III, no setae in front of stigmata of sternite IV ( Fig. 22 ). Glandular pores present on sternites IV–IX: 6: 9: 7: 7: 7: 7.

Chelicera ( Fig. 6 ) with 5 setae on hand and one seta on movable finger, 0.64 from base. Galea long and simple. Fixed finger with 16 small to medium teeth; movable finger with 5 apical protuberances and 6 teeth, two medial teeth larger than others ( Fig. 7 ); light scaly reticulation on hand and movable finger. Rallum with 5 finely serrate blades, at least the basal one shorter than others ( Fig. 8 ). Serrula exterior with 23 blades, serrula interior with 14 blades.

Pedipalps ( Figs 13–15 ). Trochanter and basal half of femur granulate, paraxial face of patella partially granulate. Femur with one glandular pore mediodistally, patella with one pore at base of pedicel and 5 more pores along medial line of article ( Fig. 13 ). Chela ( Figs 14–15 ) smooth, hand and fixed finger with peculiar and irregular outline, hand with a marked wide depression mid-way on antiaxial face, trichobothria isb -esb -eb on a wide and low bump, fixed finger with an angular kink from trichobothrium et to the tip ( Figs 14, 17 ), movable finger markedly curved and partly overlapping fixed finger distally. Hand with a distal group of glandular pores on antiaxial and paraxial faces, another pore on pedicel, trichobothrium ib on a prominent tubercle and located in basal half of hand, trichobothria isb -esb -eb forming a triangular group on distal third of hand. Fixed finger with only four trichobothria, ist isolated in basal half, est relatively close and basal to et, it far from the latter and situated close to tip; with 68 contiguous teeth ending at level of trichobothrium ist; venom duct short, nodus ramosus slightly distal of trichobothrium it; one pore or sensillum (af?) on a tubercle distal of it ( Figs 16–17 ). Movable finger with 72 contiguous teeth, long and apically rounded, ending basal to trichobothrium b; trichobothrium st close to t and both near middle of finger, sb slightly closer to st than to b but not forming a group with st -t; trichobothrium t slightly lanceolate toward tip ( Fig. 18 ); one doubled pore sensillum (pc) close to dental margin, basal to trichobothrium sb. Lyrifissures as shown in Figs 14–15 .

Leg I ( Fig. 9 ). Femur without basi-dorsal mound; femur and patella granulate, tibia and metatarsus with weak scales, tarsus smooth; claws smooth; subterminal setae with three apical rami. Leg IV ( Fig. 10 ): junction between femur and patella perpendicular; femur slightly longer than patella, both granulate, the other segments generally smooth; claws smooth; subterminal setae with three apical rami ( Figs 11–12 ); tactile setae (TS) ratios: tibia 0.54, metatarsus 0.27, tarsus 0.31. Arolium shorter than claws on all legs.

Ratios and measurements. Body: 1.64. Carapace: 0.60/0.44 (1.35×). Chelicera: hand: 0.34/0.18 (1.91×); finger: 0.21. Pedipalp: trochanter: 0.32/0.12 (2.79×); femur: 0.67/0.14 (4.81×); patella: 0.64/0.17 (3.76×), pedicel: 0.14, club: 0.50/0.17 (2.92×), club/pedicel: 3.44×; hand with pedicel: 0.40/0.22 (1.85×), hand without pedicel: 0.34/0.22 (1.55×); finger: 0.56; chela with pedicel: 0.96/0.22 (4.42×), chela without pedicel: 0.90/ 0.22 (4.09×); chela/carapace: 1.59×; femur/carapace: 1.12×; femur/finger: 1.20×; femur/patella: 1.05×; patella/hand: 1.60×; finger/hand: 1.40×. Leg I: femur: 0.33/0.09 (3.82×); patella: 0.28/0.09 (3.29×); tibia 0.31/ 0.06 (5.06×); metatarsus 0.20/0.05 (4.06×); tarsus 0.25/0.04 (5.56×); femur/patella: 1.16×; tarsus/metatarsus: 1.23×. Leg IV: femur: 0.31; patella: 0.30; femur+patella: 0.61/0.09 (6.47×); tibia 0.62/0.06 (9.97×); metatarsus: 0.26/0.05 (4.95×); tarsus 0.27/0.05 (5.51×); femur/patella: 1.05×; tibia/femur: 1.01×; tarsus/ metatarsus: 1.04×.

Distribution. The new species has only been found in the cave Avenc d’en Serenge, Castellón province, Valencian Community, Spain ( Fig. 1 ).

Biology. The species shows troglomorphic characteristics such as the absence of eyes or eye-spots, elongated carapace, pedipalps and legs, and unpigmented cuticle, but the size of the body is more like that of epigean taxa. The new species seems to be troglobitic, but an edaphic existence should also be considered.

Biogeography. The relictual condition of Arcanobisium comasi sp. nov. is implied by its unique morphological features and this is reinforced by its isolated location in a cave, the “Avenc d’en Serenge”, which belongs to an independent biogeographic region in Spain, considered as refuge for Laurasian arthropods ( Ortuño et al. 2005). Important relictual troglobites have been found in Avenc d’en Serenge and nearby caves, most of them monotypic genera and endemic to this area. These include the pseudoscorpion Troglobisium racovitzai (Ellingsen, 1912) , the only representative of the family Bochicidae in Europe, the remarkable beetle Ildobates neboti Español, 1966 ( Coleoptera : Carabidae ), the campodeid Paratachycampa hispanica Bareth & Condé, 1981 (Diplura) [this genus is also known as relicts in caves in Mexico ( Sendra 2003, 2006)] and the enigmatic japygid Gollumjapyx smeagol Sendra & Ortuño, 2006 (Diplura) ( Ortuño et al. 2005, 2006; Sendra et al. 2006).

The relictual condition of European syarinid genera has been discussed in literature. Syarinus strandi has been linked to a pre-glacial fauna by Schawaller (1987), based on the fact that other representatives of the genus are distributed in North America. The European genera formerly placed by Beier (1963) in Microcreagrellinae also show relict distribution ( Beier 1969), with Hadoblothrus and Pseudoblothrus being palaeo-endemic troglobites and survivors of an archaic fauna.

Figures

FIGURE 1. Map showing location of the type locality of Arcanobisium comasi sp. nov., the cave Avenc d’en Serenge in Castellón province, Valencian Community, Spain.

FIGURES 2 – 3. Arcanobisium comasi sp. nov., male holotype. 2. habitus, dorsal view; 3. habitus, ventral view.

FIGURES 4 – 12. Arcanobisium comasi sp. nov., male holotype. 4. carapace; 5. anterior margin of carapace, showing epistome; 6. right chelicera; 7. partial view of fingers of right chelicera; 8. cheliceral rallum; 9. right leg I, lateral view; 10. right leg IV, lateral view; 11. distal end of tarsus and apotele of right leg IV, lateral view; 12. subterminal seta of tarsus right leg IV, partial view. Abbreviations: P glandular pore; TS tactile seta. Scale bars (mm): 0.01 (Fig. 12), 0.05 (Fig. 5, 7, 8, 11), 0.10 (Fig. 6), 0.20 (Fig. 4, 9, 10).

FIGURES 13 – 18. Arcanobisium comasi sp. nov., male holotype. 13. right pedipalp, without chela, dorsal view; 14. right chela, dorsal view; 15. right chela, antiaxial view; 16. tips of fixed and movable finger of right chela, antiaxial view; 17. tips of fixed and movable finger of right chela, dorsal view; 18. trichobothrium t. Abbreviations: af? pore or sensillum; pc doubled pore sensillum (other abbreviations correspond to trichobothria). Scale bars (mm): 0.05 (Fig. 18), 0.10 (Figs 16 – 17), 0.20 (Figs 13 – 15).

FIGURES 19 – 25. Arcanobisium comasi sp. nov., male holotype. 19. coxae of pedipalp and leg I; 20. genital sternites, ventral; 21. genitalia, ventral; 22. stigmata of sternites III and IV; 23. tergites-sternites VIII – XII, posterior view, drawing in perspective, entire setae only illustrated in sternites X – XI; 24. tergites-sternites VIII – XII, lateral view; 25. habitus, lateral view; pedipalps, legs and one chelicera omitted. Abbreviations: I – XII segments I – XII of opisthosoma. Scale bars (mm): 0.05 (Fig. 21), 0.10 (Figs 20, 22, 24, 25), 0.20 (Figs 19, 23).