Occidenchthonius mahnerti, Zaragoza, Juan A., 2017

Zaragoza, Juan A., 2017, Revision of the Ephippiochthonius complex in the Iberian Peninsula, Balearic Islands and Macaronesia, with proposed changes to the status of the Chthonius subgenera (Pseudoscorpiones, Chthoniidae), Zootaxa 4246 (1), pp. 1-221 : 170-173

Occidenchthonius mahnerti n. sp. ( Figs 266–271 )

Chthonius (Ephippiochthonius) gracilimanus (not Mahnert, 1997): Mahnert 2011a: 42 (in part: misidentification of specimens from Gran Canaria).

Type locality. Spain, Canary Islands, La Palma province, Gran Canaria Island, Reserva Natural Integral del Barranco Oscuro , municipal areas of Moya and Valleseco (28°03′56″N, 15°35′32″W; 793 m a.s.l.) .

Distribution. Spain: Canary Islands.

Etymology. The species name honours Dr Volker Mahnert (MHNG), in recognition of his impressive contribution to our knowledge of pseudoscorpions around the World, and particularly to the faunas of the Iberian Peninsula and the Canary Islands.

Diagnosis (♂ ♀). A small, hypogean Occidenchthonius species with weakly developed eyes of the machadoi - group. Movable cheliceral finger with isolated subapical tooth (di) and with prominent spinneret in both sexes, lyrifissure ldb present; anterior pair of eyes with weakly convex lens, posterior eyes indistinct spots, anterior margin of carapace with 2–4 preocular microsetae on each side, posterior margin with 2 macrosetae; chelal hand distinctly depressed at level of ib / isb, with a short, prominent hump distad of ib / isb and moderate slope between trichobothria ib / isb and eb, chaetotaxy 4:4:4; fixed chelal finger with 20–21 teeth; distal half of movable chelal finger with 12–15 pointed teeth with dental canals, basal half of movable chelal finger with 10–12 rounded, partially fused, vestigial teeth, without canals, on raised lamina; pedipalpal femur (♂) 5.7, (♀) 5.8 times longer than broad, length (♂) 0.60 mm, (♀) 0.64–0.68 mm; chela (♂) 6.2, (♀) 5.9 times longer than deep, length (♂) 0.84 mm, (♀) 0.83–0.91 mm; ratio movable chelal finger/chelal hand (♂) 1.6, (♀) 1.5–1.6; lacking lyrifissures ma1 and ma2, all other chelal lyrifissure patterns present with their standard complements.

Type material examined. ♀ holotype, 1 ♀ paratype ( DZUL, DEUA), Spain, Canary Islands, La Palma province, Gran Canaria Island, Reserva Natural Integral del Barranco Oscuro , municipal areas of Moya and Valleseco (28°03′56″N, 15°35′32″W; 793 m a.s.l.), MSS, 14.VIII.2006, leg. H. López ; same location (MSS): 2 ♀ paratypes ( DZUL), 28.III.2003 , 1 ♂ (DEUA), 1 ♀ (DZUL) paratypes, 04.I.2006, leg. H. López.

Description (♂ ♀). Small, hypogean species of MSS. Integument weakly depigmented; hispid granulation on lateral surfaces of carapace, on cheliceral hand and on bases of chelal fingers.

Carapace ( Fig. 267 ) slightly longer than broad and weakly constricted posteriorly; medial part of anterior margin distinctly prominent, without a well-defined epistome, and strongly dentate ( Fig. 266 ); anterior eyes small, with weakly convex lens (diameter 0.030–0.038 mm) and reflecting tapetum, 0.035–0.045 mm from anterior margin of carapace, posterior eyes reduced to very weak lenses or eye-spots, 0.035–0.050 mm from anterior eyes and diameter 0.030–0.038 mm. Chaetotaxy: 18 setae, rarely 19, with 2–4 preocular microsetae on each side, 2 setae in posterior row (exceptionally 1 specimen with an additional posterolateral tiny seta), macrosetal formula 4:6:4:2:2, anteromedial setae 0.15–0.18 mm long, sublateral ocular setae 0.08–0.09 mm; 4 lyrifissures anteriorly and 2 posteriorly.

Chelicera ( Figs 268, 269, 271 ) with 6 setae and 4 lateral microsetae on hand, seta vb short (0.025–0.040 mm long), microsetae 0.013–0.023 mm; hand with 5 dorsal and 1 ventral lyrifissure, lyrifissure ldb present. Fixed finger with 9–11 teeth decreasing in size proximally, two distal teeth distinctly larger than others, 2 proximal microtubercles. Movable finger with an isolated subapical tooth (di), with 8–9 teeth decreasing in size proximally, the distal tooth larger than others; spinneret prominent and apically rounded in female ( Fig. 269 ), slightly smaller in male ( Fig. 271 ); seta gl 0.56–0.58 from base of movable finger. Rallum with 11 blades. Serrula exterior with 15 blades, serrula interior 12 blades.

Chaetotaxy of tergites 4:4:4:4:6:6:6:6:1T2T1:4:1T2T1:0, tergites IX and XI each with 2 sublateral tactile setae, tactile seta X 0.15–0.19 mm long. Chaetotaxy of sternites 9–10:(3)7–8(3):(2)7–8(2):7–8:6:6:6:6:2T1T2:0:2, lateral setae on sternite III macrosetal in size, sternite X with 2 submedial tactile setae; in addition, genital notch of male flanked by 7 setae on each side and 4+4 internal glandular setae.

Pedipalpal coxa with 5 setae (including 2 on manducatory process), distal marginal seta of disk 0.08–0.09 mm long; coxa I 3 + 3 marginal microsetae, distal marginal seta 0.07–0.08 mm long; II 4 + 7–10 bipinnate coxal spines, III 5 + 4–6 bipinnate coxal spines and IV 6; intercoxal tubercle bisetose.

Pedipalp with femoral chaetotaxy 3:6:3:5:1. Chela ( Fig. 270 ) with hand distinctly depressed at level of ib / isb, with a short, prominent hump distad of ib / isb and moderate slope between trichobothria ib / isb and eb; distinct hollow before base of movable finger with thicker cuticle; width equal to or shorter than depth, maximum width proximad of trichobothria ib / isb; chaetotaxy 4:4:4, seta ph3 present, seta ih5 absent; distal end of hand and bases of chelal fingers with sclerotized condylar complex. Fixed finger with 20–21 mostly pointed teeth and with dental canals, 4 more proximal teeth progressively decreasing in size, of these the most proximal still pointed or rounded, first two distal teeth small, third tooth of normal row (mt) of fixed finger distinctly modified in shape and deviated in orientation with respect to the others, dental row reaching up to proximad of trichobothrium sb, about 15 proximal microtubercles; tip of finger with an accessory tooth (td) on antiaxial face; tip of fixed chelal finger of male with a weak hollow on paraxial face, without subdistal protuberance (sp); one pair of long antiaxial sensory setae (as) at the base, both distad of lyrifissure fb, 0.030–0.043 mm long, distance between them 0.028–0.045 mm, fixed finger depth at the base 0.050–0.055 mm; 5 teeth at level of est / it occupying 0.1 mm, distance between successive apices 0.020–0.023 mm. Distal half of movable finger with 12–15 pointed teeth with dental canals that reach up to halfway between trichobothria st and sb, two distal teeth tiny or small; basal half of movable chelal finger with 10–12 rounded, partially fused, vestigial teeth, without canals, on weakly raised lamina; dental row reaching level of sensilla pc, 5–7 proximal microtubercles; basal apodeme long and apically indented; coupled sensilla pc between trichobothria sb and b, closer to sb. Trichobothria as in Fig. 270 ; trichobothrium ist slightly proximad of esb and well proximad of lyrifissure fb; distance between ib / isb and esb 1.1 longer than that between ib / isb and the base of the hand; distance between st and sb 1.6–2.0 times longer than that between sb and b; lacking lyrifissures ma1 and ma2, all other chelal lyrifissure patterns present with their standard complements.

Measurements and ratios. Female holotype, followed by female paratypes in square brackets: Body 1.41 [1.46–1.50]. Carapace 0.48/0.48 (1.0) [0.47–0.48/0.44–0.46 (1.0–1.1)]. Chelicera 0.45/0.22 (2.0) [0.41/0.20 (2.1)], movable finger 0.23 [0.20]. Pedipalp: femur 0.68/0.12 (5.8) [0.64/0.11 (5.8)], patella 0.28/0.13 (2.1) [0.27/0.13 (2.2)], chela 0.91/0.15 (5.9) [0.83/0.14 (5.9), hand 0.35 (2.3) [0.33 (2.4)], movable finger 0.55 [0.50]; ratio movable finger/hand 1.6 [1.5], femur/movable finger 1.2 [1.3], femur/carapace 1.4 [1.3], chela/carapace 1.9 [1.7], chela/femur 1.3. Male paratype: Body 1.34. Carapace 0.43/0.42 (1.0). Chelicera 0.38/0.19 (2.0), movable finger 0.20. Pedipalp: femur 0.60/0.11 (5.7), patella 0.25/0.12 (2.2), chela 0.84/0.14 (6.2), hand 0.32 (2.4), movable finger 0.51; ratio movable finger/hand 1.6, femur/movable finger 1.2, femur/carapace 1.4, chela/carapace 2.0, chela/ femur 1.4.

Remarks. Within the machadoi -group, O. mahnerti n. sp. is endemic to Gran Canaria Island. It was previously misidentified as O. gracilimanus by Mahnert (2011a), who examined some samples from Gran Canaria Island and recognized differences from the types, but was unsure about their significance. It differs from O. gracilimanus by the presence of chelal lyrifissure hd. O. mahnerti n. sp. is close to the Canarian species O. beieri n. sp. and O. tamaran , the main difference from both those species being the teeth arrangement on the movable chelal finger, as given in the key. The distribution range of O. gracilimanus seems to be limited to La Palma Island.

Figures

FIGURES 266 – 271. Occidenchthonius mahnerti n. sp., female holotype (266 – 270) and male paratype (271). 266, anterior margin of carapace, partial view; 267, carapace; 268, left chelicera; 269, fingers of left chelicera, partial view; 270, left chela, antiaxial view; 271, movable finger of left chelicera, partial view.