Pseudochthonius arabicus Mahnert

Mahnert, Volker, Sharaf, Mostafa & Aldawood, Abdulrahman S., 2014, Further records of pseudoscorpions (Arachnida, Pseudoscorpiones) from Saudi Arabia, Zootaxa 3764 (3), pp. 387-393 : 388-391

Pseudochthonius arabicus Mahnert n. sp.

( Figs 1–2 )

Material examined. Holotype ♂ ( MHNG), Saudi Arabia, Al Bahah, Al Mukwah, Dhi Ayn Archeological Village , 11.v.2011, 20°12′39.7″N, 41°26′30.2″E, 741 m. Paratype ♀ ( KSMA), same data .

Description. General coloration yellowish brown, tergites III–VI with a dark median mark. Carapace 1.1 × longer than broad, slightly constricted posteriorly and there reticulated ( Fig. 1 a); two small eyes with distinct lenses present, about one diameter from anterior margin; epistome ( Fig. 1 b) broad and dentate; 16 long setae (4 + 1 pair preocular seta/4/4/2/2); tergal chaetotaxy: I–IV 4, VI–IX 6, X 4, XI 6 (2 tactile setae). Manducatory process acute, with 2 setae; pedipalpal coxa 3 (one discal seta in basal third), coxa I 3 long setae and one tiny seta on anterior margin + 4–5 dentate (median one apparently smooth) coxal spines in single row, II 4 setae + 5–6 dentate (median one apparently smooth) coxal spines ( Fig. 1 f), III 7 setae, IV 8 setae, intercoxal tubercle absent. Anterior genital operculum of ♂ (not observable in ♀) with 9 marginal and discal setae, genital opening of ♂ slit-like triangular ( Fig. 1 g), with 7–8 unmodified marginal setae on each side; sternal chaetotaxy III–XI (♂): 8 + 3 pairs suprastigmal setae/8 + 3 pairs suprastigmal setae/9 (2 lateral setae on each side tiny)/8 (lateral setae tiny)/8 (lateral setae short)/8/8/9/0.

Chelicera ( Fig. 1 c): hand with 4 long and 2–3 shorter, basal, accessory setae, fixed finger with 10–11 acute teeth, movable finger with 11–14 small acute teeth and one slightly isolated distal tooth; subgaleal seta in basal third of movable finger; galea tubercle-like (slightly larger in ♀ than in ♂), serrula exterior 14–17 lamellae, rallum with about 9 setae with long denticles.

Pedipalps ( Fig. 1 d, e): trochanter 1.6 (♀ 1.6) × longer than broad, femur 4.9 (♀ 5.0) ×, patella 2.3 (♀ 2.2) × longer than broad, hand 2.0 (♀ 1.9) ×, chela 6.4 (♀ 6.2) × longer than deep, fixed finger 2.2 (♀ 2.3) × longer than hand; fixed finger with 33–35 acute, erect teeth, in distal half, of alternating length and in saw-like arrangement, movable finger shorter than the fixed one, with 37–39 low retrorse teeth; trichobothrium ist twice nearer to esb than to est.

Leg I: femur 5.1 (♀ 4.8.) × longer than deep and 1.6 × longer than patella, patella 3.4 (♀ 3.7) ×, tibia 5.0 (♀ 4.4) ×, tarsus 9.9 (♀ 9.4) × longer than deep; leg IV: femur+patella 2.4 (2.4) ×, tibia 4.0 (♀ 4.1) ×, basitarsus 3.1 (♀ 3.2) ×, telotarsus 9.9 × (♀: broken) longer than deep and 1.5 × longer than basitarsus.

Measurements of ♂ (♀) in mm: Total length 1.27 (1.91). Carapace (length/breadth) 0.44/0.40 (0.48/0.44). Pedipalps (length/breadth): trochanter 0.17/0.11 (0.19/0.12), femur 0.55/0.11 (0.61/0.12), patella 0.23/0.10 (0.25/ 0.12), hand length/depth 0.24/0.12 (0.26/0.14), length of fixed finger 0.54 (0.59), of movable finger 0.50 (0.53), of chela 0.77 (0.85). Leg I (length/depth): femur 0.30/0.06 (0.32/0.07), patella 0.19/0.05 (0.20/0.05), tibia 0.19/0.04 (0.17/0.04), tarsus 0.31/0.03 (0.31/0.03); leg IV: femur+patella 0.49/0.21 (0.50/0.21), tibia 0.31/0.08 (0.32/0.08), basitarsus 0.17/0.06 (0.18/0.06), telotarsus 0.33/0.03 (-).

Affinities. The known geographical distribution of the 29 species of Pseudochthonius Balzan, 1892 (28 extant and one fossil species) was previously restricted to sub-Saharan Africa and South America north to Mexico. Five species have been reported from Africa, and the new species seems to be morphologically similar to those from central and eastern Africa. Whereas trichobothrium ist is approximately halfway between esb and est in P. billae Vachon, 1941 ( Ivory Coast) and P. leleupi Beier, 1959 ( Zaïre) , ist originates>2× closer to esb than to est in P. congicus Beier, 1959 ( Zaïre) and P. perreti Mahnert, 1986 ( Kenya) . Pseudochthonius arabicus is distinguishable from the latter two species by its much larger size (chela length 0.77–0.85 mm, versus 0.38 mm in P. perreti or 0.53 mm in P. congicus ). Furthermore it differs from P. congicus in having a distinct epistome (lacking in P. congicus ) and from P. perreti by the presence of distinct, lensed eyes (eyes indistinct, without lenses, in P. perreti ).

The presence of this genus in the southwestern mountains of the Arabian Peninsula confirms the affinity of this region with the Afrotropical faunal realm.

Remarks. The type locality ( Fig. 2 a, b) is a national archaeological site that is completely surrounded by mountains. It forms part of the upper Tihama Territory, belonging to Al Bahah Province. The locality has a high diversity of native vegetation, but numerous fruits are cultivated (e.g. banana, date palm and Ficus ), along with alfalfa, and lemon orchards have been planted. There are several permanent drainages and localized soil moisture is higher than in surrounding regions.

The holotype male of P. arabicus was found under a stone next to a large, older Ficus tree, close to a small stream that is part of an agricultural irrigation ditch system ( Fig. 2 c). Two ant ( Formicidae ) species were found with the new pseudoscorpion: Pheidole pallidula (Nylander, 1849) and Tetramorium sericeiventre Emery, 1877 . Additionally, several other myrmecophilous arthropods were collected in the same area, including: Centrophthalmus subtilissimus Hlaváč, 2013 ( Coleoptera : Pselaphinae ); Pinophilinus spinosus Assing, 2013 ; an undescribed Peltodonia sp. ( Coleoptera : Staphylinidae ) and unidentified species of the family Anthicidae (Coleoptera) . The paratype female was collected by sifting leaf litter under banana in company with the ants Carebara arabica Collingwood & Van Harten, 2001 , Tapinoma wilsoni Sharaf & Aldawood, 2012 , Cardiocondyla emeryi Forel, 1881 , Hypoponera sp. and Messor sp.

Figures

FIGURE 1. Pseudochthonius arabicus Mahnert n. sp., holotype. a, carapace (most setae fallen off); b, epistome; c, right chelicera; d, left pedipalp, minus chela, dorsal view; e, left chela, lateral view; f, left coxae I and II with details of coxal spines; g, genital opening. Scale units 0.1 mm.

FIGURE 2. Type locality of Pseudochthonius arabicus Mahnert n. sp. a, Map of Saudi Arabia, showing location of site; b, Al Bahah, Al Mukwah Dhi Ayn Archeological Village (type locality), (photograph by M. Abdel-Dayem); c, Habitat (photograph by M. Sharaf).