Occidenchthonius minutus Vachon 1940, n. comb.
Creators: name: Zaragoza, Juan A.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Pseudoscorpiones
Chthoniidae
Occidenchthonius
Occidenchthonius minutus

description: Occidenchthonius minutus (Vachon, 1940), n. comb.
(Figs 277–279)
Chthonius (Ephippiochthonius) minutus Vachon 1940: 13 ‒15, figs 7‒11. Chthonius (Ephippiochthonius) minutus: Zaragoza 2007: 18.
Type locality. Portugal, Algarve region, Faro district, Portimão, Mexilhoeira Grande, Cêrro do Algarve, Mina dos Mouros.
Distribution. Portugal: Algarve region.
Diagnosis (♀). A small, hypogean, weakly troglomorphic Occidenchthonius species. Movable cheliceral finger with isolated subapical tooth (di) and spinneret prominent in female, unknown for male; lyrifissure ldb present; without eyes or eye-spots, anterior margin of carapace with 1 preocular microsetae on each side, posterior margin with 2 macrosetae; chelal hand weakly depressed at level of ib / isb, with short and very weakly prominent hump distad of ib / isb and gentle slope between trichobothria ib / isb and eb; trichobothrium ist proximad of lyrifissure fb; fixed chelal finger with 14 teeth; distal half of movable chelal finger with 9 pointed teeth with dental canals, basal half of movable chelal finger with 6 rounded, partially fused, vestigial teeth, without canals, on raised and short lamina; pedipalpal femur (♀) 5.8 times longer than broad, length 0.52 mm; chela (♀) 5.2 times longer than deep, length 0.70 mm; ratio movable chelal finger/chelal hand (♀) 1.4; lacking lyrifissures ma1, ma2 and hp, all other chelal lyrifissure patterns present with their standard complements.
Type material examined. ♀ holotype (MNHN; mounted on 2 slides), Portugal, Algarve region, Faro district, Portimão, near Mexilhoeira Grande, Cêrro do Algarve, Mina dos Mouros, leg. A. de B. Machado.
Description (♀; ♂ unknown). Small, hypogean species, weakly troglomorphic. Integument depigmented.
Carapace (Fig. 277) as long as broad, distinctly constricted posteriorly; medial part of anterior margin slightly prominent, without epistome, and strongly dentate. Without eyes or eye-spots. Chaetotaxy: 18 setae, with 1 preocular microseta on each side, 2 setae in posterior row, formula m 4m:6:4:2:2.
Chelicera (Fig. 278) with 6 setae and 1 lateral microseta on hand, seta vb short (0.025 mm long), microsetae 0.018 mm; hand with 5 dorsal and 1 ventral lyrifissure, lyrifissure ldb present. Fixed finger with 6 teeth decreasing in size proximally, two distal teeth distinctly larger than others, 2 proximal microtubercles. Movable finger with an isolated subapical tooth (di), with 4–5 teeth decreasing in size proximally, the distal tooth larger than others; spinneret prominent in female, unknown for male; seta gl 0.54 from base of movable finger.
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. Chaetotaxy of sternites 10:(3)6(3):(2)6(2):7:6:6:6:6:2T1T2:0:2, sternite X with 2 submedial tactile setae.
Pedipalpal coxa with 5 setae (including 2 on manducatory process), distal marginal seta of disk 0.08 mm long; coxa I 3 + 3 marginal microsetae, distal marginal seta 0.06 mm long; II 4 + 7–8 bipinnate coxal spines, III 5 + 3–4 bipinnate coxal spines and IV 6; intercoxal tubercle bisetose.
Pedipalp with femoral chaetotaxy 3:6:3:5:1. Chela (Fig. 279) with hand weakly depressed at level of ib / isb, with short and very low rounded prominent hump distad of ib / isb and gentle slope between trichobothria ib / isb and eb; distinct hollow before base of movable finger; chaetotaxy 4:5(uncertain):4, seta ph3 present; distal end of hand and bases of chelal fingers with sclerotized condylar complex. Fixed finger with 14 mostly pointed teeth and with dental canals, 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, most proximal 2 teeth slightly smaller than the others, dental row reaching up to level of trichobothrium sb, 8 proximal microtubercles; tip of fixed finger with an accessory tooth (td) on antiaxial face; one pair of long antiaxial sensory setae (as) at the base, one level with and other markedly distad of lyrifissure fb, 0.040 mm long, distance between them 0.038 mm, fixed finger depth at the base 0.046 mm; 5 teeth at level of est / it occupying 0.1 mm, distance between successive apices 0.025 mm. Distal half of movable finger with 9 pointed teeth with dental canals that reach up to halfway between trichobothria st and sb, the distal tooth tiny; basal half of movable chelal finger with 6 rounded, partially fused, vestigial teeth, without canals, on raised and short lamina; dental row reaching up to level of trichobothrium sb, 3 proximal microtubercles; basal apodeme long and apically indented; coupled sensilla pc between sb and b, distinctly closer to sb. Trichobothria as in Fig. 279; trichobothrium ist distinctly distad of esb and distinctly 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 2.0 times longer than that between sb and b; lacking lyrifissures ma1, ma2 and hp, all other chelal lyrifissure patterns present with their standard complements.
Measurements and ratios. Female holotype: Body 1.25. Pedipalp: femur 0.52/0.08 (5.8), patella 0.20/0.10 (2.0), chela 0.70/0.13 (5.2), hand 0.28 (2.1), movable finger 0.40; ratio movable finger/hand 1.4, femur/movable finger 1.3, chela/femur 1.3.
Remarks. Occidenchthonius minutus does not belong to either of the species-groups recognized within the genus. It is an anophthalmic species with an isolated subapical tooth (di) on the movable cheliceral finger and preocular microsetae. It shares these characteristics with O. morenoi, but they are easily separated by the position of trichobothrium ist, distinctly distad of esb in O. minutus, versus slightly proximad in O. morenoi, and by their very different size and degree of troglomorphy, with O. minutus being smaller and less troglomorphic than O. morenoi. It shares with O. sendrai the position of ist (distinctly distad of esb, but proximad of lyrifissure fb), but differs by the presence of preocular microsetae and the smaller, more robust pedipalp. O. minutus seems to be restricted to the hypogean environment in Portugal, the single record from Spain (Carabajal Márquez et al. 2011) having been invalidated by Zaragoza & Pérez (2013). The above description incorporates in part that of Vachon (1940).
description: Published as part of 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), pp. 1-221 in Zootaxa 4246 (1) on pages 176-178, DOI: 10.5281/zenodo.437611