Wadicosa arabica Kronestedt, Feulner & Roobas, 2024, sp. nov.
Creators: name: Kronestedt, Torbjörn
name: Feulner, Gary R.
name: Roobas, Binish
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Lycosidae
Wadicosa
Wadicosa arabica

description: Wadicosa arabica sp. nov.
(Figs 1, 2A‒D, 3‒4, 5C‒E, 6)
Pardosa sp. A ”Hajar Wadi Pardosa ”: Feulner & Roobas 2015: 47, figs 31.1‒2 (live ♂ ♀).
Type material. Holotype ♂ from UNITED ARAB EMIRATES, Fujairah: Wadi Wurayah, 25°23’41’’N, 56°16’02’’E, 10 Nov. 2022, leg. G.R. Feulner, in NHRS. ‒ Paratypes. OMAN, Ash-Sharqiyyah South: Quhaid, 21°09’N, 58°55’E (probably wrong locality, see below), 18 Feb. 1986, 1♂ (Oman Eastern Sands Project, W. Büttiker, NHMB). UNITED ARAB EMIRATES, Fujairah: Wadi Wurayah, 25°23’41’’N, 56°16’02’’E, 10 Nov. 2022, 3♀ (incl. allotype) (G.R. Feulner, NHRS); same locality, 25°22’58’’N, 56°15’45.5’’E, 15 Dec. 2022, 3♂ (G.R. Feulner, NHRS).
Etymology. The specific epithet refers to the presence of this species in the Arabian Peninsula.
Diagnosis. The male differs from congeners by the spear-like shape of the posteriad directed branch (TAp in Fig.3C) of the tegular apophysis, the long and narrow embolus with its apex forming two sharply cut halves, and the medially situated posterior retrolateral tegular process (pp in Fig. 3C). The female differs from congeners by the configuration of the epigyne, with epigyneal cavity about twice as wide as long and foveola (fo in Fig. 4C) somewhat elongate and partly confluent. For comparison with male palp and epigyne of W. fidelis see Fig. 2E‒H.
In the field, males (Fig. 5C‒D) may be readily separated from those of W. fidelis. In the latter (Fig. 5F), the colour pattern of the carapace includes blackish sides (sometimes with a few lighter lateral spots) flanking a pale tan, contrasting, roughly urn-shaped median field with jagged edges, which extends anteriorly to the posterior median eyes.
Description. Male (holotype). Total length 6.80. Carapace 3.70 long, 3.00 wide.
Prosoma (Fig. 1A). Carapace dark (sooty) yellowish grey with dark yellow median field, wide around fovea with edges jagged. Lateral bands yellowish, covered with white setae, in the front part broken into spots. Sides of thoracic part with recumbent black and adpressed thin light setae. Median band with adpressed light and scattered dark setae. Clypeus sooty, brownish laterally. Chelicerae reddish brown, distally more yellowish, with darker elongate markings. Sternum yellowish grey.
Eyes. Width of row I 64 (slightly recurved as seen from front), row II 95, row III 118, row II‒III 92. Diameter of AME 14, ALE 11, PME 36, PLE 32. Distance between AME 10, between AME and ALE 3.
Legs (Table 1). Yellow with dark greyish annulation except on Ta. Coxae light yellow.
Opisthosoma (Fig. 1A). Dorsum blackish with pattern of yellowish spots. Lanceolate stripe blackish. On each side of lanceolate stripe one spot basally, and one spot at about half-length and one spot posteriorly. Yellowish transverse bars rearwards from lanceolate stripe. Yellowish spots with whitish setae, otherwise black setae on dorsum. Sides with black and adpressed whitish setae. Venter light greyish with dense covering of long, recumbent light and scattered dark setae.
Palp (Figs 2A, 3). Pt 0.70, Ti 0.75, Cy 1.75. Fe dark yellowish grey, distally light yellow with white setae. Pt and Ti light yellow with dense, long, white setae and scattered erect dark bristles. Cy blackish brown, slightly lighter distally. Tegular apophysis with transversal branch directed retrolaterad, apically bent posteriad; posteriad directed branch spear-like and heavily sclerotized (Figs 2A, 3). Tegulum with spearlike anterior retrolateral process directed ventrally, rearwards continuing into a conspicuous sclerotized scutra which retrolaterally forms a wide rounded crest-like projection and more postero-medially a heavily sclerotized rounded posterior retrolateral process directed obliquely anteriad (Fig. 3). Conductor as in Figs 2A, 3. Embolus (Figs 2A‒C, 3) long and narrow, forming a conspicuous bend over upper branch of tegular apophysis, apically bipartite.
Female (allotype). Total length 7.1. Carapace 3.95 long, 3.15 wide.
Prosoma (Fig. 1B). Carapace greyish brown. Wide median yellow field with jagged edges enclosing fovea. Lateral bands present as yellow spots, the two rear ones more or less confluent. Clypeus yellowish brown, Chelicerae reddish brown, furnished with short whitish and stiff erect dark setae. Sternum light yellow with slight greyish tinge.
Eyes. Width of row I 65 (slightly recurved as seen from front), row II 98, row III 127, row II‒III 94. Diameter of AME 16, ALE 10, PME 34, PLE 30. Distance between AME 10, between AME and ALE 3.
Legs (Table 1). Yellow with dark greyish annulation except on Ta. Coxae light yellow.
Opisthosoma (Fig. 1B). Dorsally patterned in blackish and yellowish grey and covered with long and short dark setae, with a row of about five yellowish spots on each side of lanceolate stripe and further backwards. Each spot with dark dot within. Behind second pair of yellow spots, as counted from the front, a transverse row of four white spots (setae tufts), two on each side in the lateral and dorso-lateral positions; several similar but less prominent rows are present posteriorly, all being more conspicuous in life, less so after preservation (cf. Fig. 5E). Venter light yellowish with adpressed white pubescence and short thin dark setae.
Epigyne (Figs 2D, 4). Epigyneal cavity about twice as wide as long, bottom corrugated, slightly widening posteriorly. Anterior part of epigyneal cavity covered by small protruding outgrowths, in front of these median depression occupied by two elongated foveolae, in part confluent and open posteriorly. Spermathecae large, somewhat reniform, with laterad portions bilobed (Fig. 4B, D).
Size variation. Carapace length: males 3.40‒3.70 (N = 5), females 3.50‒3.95 (N = 3).
Egg sacs. Two egg sacs measured 5.2 x 4.0 and 5.2 x 4.4 mm respectively (lenticular in shape), containing 66 and 75 juveniles respectively.
Habitat. Wadicosa arabica is active diurnally on gravel, pebbles and cobbles beside wadi pools or gently flowing channels in the wadis of the Hajar Mountains (sensu stricto) of the UAE and neighbouring Oman (Feulner & Roobas 2015, Feulner 2023, 2024; Fig. 5A‒B) and can be a common predator in those discrete habitats, especially after rainfall has replenished the wadis. It is found most often where the gravel substrate remains damp and it is not unusual for it to walk (or run) on the water surface. On one occasion when the spiders were common after rainfall, several individuals were seen to take shelter from human observers in tiny holes burrowed vertically in a low, damp gravel bank (as observed by GRF and BR in December 2022), behaviour which is atypical in pardosoid spiders.
It should be noted specifically that W. arabica has never been observed in the mountains of the Musandam peninsula (the Ru’us al-Jibal range), at the northern end of the UAE-Oman mountain chain, and it is believed to be absent from there. The most likely reason is that the hydrology limits suitable habitat. The Hajar Mountains (sensu stricto), which account for most of the mountains of the UAE and northernmost Oman, consist of rocks which facilitate the formation of intermittent surface pools and streams and hyporheic flow. In contrast, the Ru’us al-Jibal range is a thick sequence of rocks that weather in a karstic fashion, with the result that surface water is very rare and flowing streams even more so, and very ephemeral (Feulner 2011).
The congeneric W. fidelis is common and widespread and its distribution range in the UAE has been expanded in recent decades by the construction of dams and water breakers, behind which it inhabits the drying silt deposited by occasional floodwaters. W. fidelis is found in a diversity of mesic habitats, all characterized by fine-grained substrates—silt or fine sand or soil, while W. arabica prefers coarser substrates of wadi gravel, pebbles, and cobbles. It is unusual to find them together due to their difference in habitat preferences.
Courtship. GRF and various companions have observed the male’s courtship display in W. arabica sp. nov. on many occasions over more than 25 years. It is described as consisting of periodic repetitions, usually from an elevated perch, of a few staccato raising and lowering movements in unison of the male’s pedipalps, which have a contrasting white colour (i.e. distal femur, patella and tibia) with black tips (i.e. cymbium) (e.g. Feulner & Roobas 2015). After a few repetitions in one place, the male spider moves to another. The female’s response has never been observed. In comparison, the male’s courtship in W. fidelis also consists of a few raisings and lowerings of the palps in unison, similar to that in W. arabica but at a slower pace and while elevating the whole body in an exaggerated stance (‘tip-toeing’) (as observed by GRF and BR on multiple occasions and at multiple sites in February 2024). Since observed courtships have never resulted in copulation, we are uncertain whether additional behavioural elements are involved in a typical courtship.
Distribution. Oman, United Arab Emirates (Fig. 6). The single male reportedly collected in Quhaid in Oman was probably mislabelled. Quhaid is situated in the south of the Wahiba Sands desert and is likely uninhabitable by this species.
Vladimir Hula (in litt. 2017) stated, after seeing our Fig. 2A, that he had collected material of W. arabica in northern Oman, regrettably now unavailable to the authors. GRF and various companions have observed (but not collected) the species in the Hajar Mountains both in the UAE and northernmost Oman (e.g. Feulner & Roobas 2015) over more than 25 years. However, GRF has not observed W. arabica in the course of a limited number of visits to the south-easternmost mountain areas in Oman, and inquiries to Oman-based entomologists have also failed to elicit any records from that area. A southern record most probably referring to this species was mentioned in Cowan et al. (2020).
Final remarks
A part of the species in the genus Wadicosa have been separated into species groups based on the shape of the tegular apophysis and the embolus in the male palps (Kronestedt 2023). The fidelis group is the most speciose, previously encompassing six species (Kronestedt 2015) distributed over Africa (westernmost in Cape Verde Is), southern Europe and Asia (easternmost in New Guinea). It is characterized by the tegular apophysis having a conspicuous transversal, less pigmented branch directed retrolaterad, a characteristically coiled embolus and a ditto shaped conductor as well as a conspicuous scutra. W. arabica belongs within the fidelis group and exhibits its closest morphological similarities to W. commoventa in the configuration of the tegular apophysis (with a posteriad directed branch) and epigyne (cf. Zyuzin 1985, figs 13‒14, 17‒19). The latter species was described on the basis of material from Turkmenistan and has since been found much further south at a locality in Kerman Province in Iran (Zamani et al. 2017), indicating a wider distribution range.
Wadicosa arabica is so far known only from wadis in the mountain areas of northern Oman and northeastern UAE, i.e., the Hajar Mountains sensu lato. That area is known to be a centre of species endemism (Feulner 2011, 2024, Monks et al. 2019) but it also has many floral and faunal affinities with southern Iran and Baluchistan—a socalled Oman-Makran distribution (Kürschner 1986, Feulner 2011, 2024). Like a number of localized arthropods and other species in southeastern Arabia, W. arabica is not uncommon and has been known to UAE- and Oman-based naturalists for many years. It remains to be finally determined, however, whether the distribution of W. arabica is restricted to the currently known range or whether it might extend to the Makran or to the southerly Dhofar province of Oman or beyond.
description: Published as part of Kronestedt, Torbjörn, Feulner, Gary R. & Roobas, Binish, 2024, Species of Wadicosa (Araneae, Lycosidae): a new species from the southeastern Arabian Peninsula, pp. 291-300 in Zootaxa 5523 (2) on pages 292-299, DOI: 10.11646/zootaxa.5523.2.10, http://zenodo.org/record/13934131