Micropholcus tanomah Huber sp. nov.

Figs 3 F, 5 A, G, 6 C, 7 C – G, 9 B, F, G, 10 A, B, 11 A, F, 12 A – D, 39, 40, 41, 42

Type material.

Holotype. Saudi Arabia – ‘ Asir • ♂; NW of Tanomah; 19.0220 ° N, 42.1247 ° E; 2250 m a. s. l.; 19 Mar. 2024; B. A. Huber leg.; KSMA . Paratypes. Saudi Arabia – ‘ Asir • 21 ♂♂, 24 ♀♀, 1 juv. (1 ♂, 1 ♀ used for SEM); same collection data as for holotype; ZFMK Ar 24663 to 24664 .

Other material.

Saudi Arabia – ‘ Asir • 3 ♀♀, 4 juvs; in pure ethanol; same collection data as for holotype; ZFMK SA 100 .

Diagnosis.

Distinguished from similar species in the northern Saudi Arabian group ( M. bashayer sp. nov., M. maysaan sp. nov.) by very slender main bulbal process (Fig. 40 D; wider in other species), and by epigynal ‘ knob’ in posterior rather than central position on epigynal plate (Fig. 42 A, B); from M. maysaan sp. nov. also by less widened hinged process of procursus (Fig. 40 C); from species of the southern Saudi Arabian group and M. jacominae by shorter male palpal trochanter apophysis (Fig. 39 C), internal female genitalia with membranous central element rather than distinct arc (Fig. 41 C), and without crescent-shaped structures.

Description.

Male (holotype). Measurements. Total body length 3.4, carapace width 1.2. Distance PME - PME 210 µm; diameter PME 80 µm; distance PME - ALE 20 µm; distance AME - AME 20 µm; diameter AME 45 µm. Leg 1: 28.7 (7.0 + 0.5 + 7.1 + 12.7 + 1.4), tibia 2: 4.5, tibia 3: 2.9, tibia 4: 4.0; tibia 1 L / d: 71; diameters of leg femora (at half length) 0.11–0.12; of leg tibiae 0.10.

Colour (in ethanol). Carapace pale ochre-yellow with distinct brown mark, ocular area not darkened, clypeus with very indistinct darker pattern; sternum monochromous whitish; legs ochre-yellow to light brown, patella dark brown, tibia-metatarsus joints with small brown ring, femur 1 ventrally proximally brown (less distinct also femur 2); abdomen pale ochre-grey, with indistinct darker internal marks.

Body. Habitus as in Fig. 3 F. Ocular area slightly raised (distinct in frontal view). Carapace without thoracic groove. Clypeus unmodified. Sternum wider than long (0.74 / 0.58), unmodified. Abdomen oval, approximately twice as long as wide. Gonopore with four epiandrous spigots (Fig. 10 A). Spinnerets as in Fig. 9 F, G.

Chelicerae. As in Fig. 41 A, B; with pair of distal apophyses near laminae, each with two cone-shaped hairs (Fig. 6 C); with pair of distinct proximal frontal apophyses; with pair of very low and indistinct lateral humps.

Palps. As in Fig. 39; coxa unmodified; trochanter with long ventral apophysis with distinct proximal retrolateral hump and modified hair on distal tip (Fig. 9 B); femur distally widened, with subdistal ventral hump; femur-patella joints shifted toward prolateral side; tibia-tarsus joints shifted toward retrolateral side; tarsus with large tarsal organ. Procursus (Fig. 40 A – C) proximally with sclerotised prolateral hump; at half length with prolateral sclerotised ridge transforming distally into transparent membrane, and brush of dorsal hairs; distally with small retrolateral ridge, large bifid membranous ventral-prolateral flap (Fig. 7 C, D), and dorsal hinged process. Genital bulb (Fig 7 F, G, 40 D, E) with strong proximal sclerite; with two sclerotised processes of unclear homology: prolateral process long and slender, with small, pointed branch on retrolateral side; retrolateral process simple, originating from basis of embolus and directed parallel to prolateral process; and mostly semi-transparent short embolus with membranous extensions.

Legs. Without spines, without curved hairs, without sexually dimorphic short vertical hairs; retrolateral trichobothrium of tibia 1 at 6 %; prolateral trichobothrium absent on tibia 1; tarsus 1 with> 20 pseudosegments, distally distinct.

Variation (male). Tibia 1 in 21 other males: 5.1–7.3 (mean 6.5). Carapace pattern very consistent. Abdomen usually with large white marks dorsally and laterally.

Female. In general very similar to male but anterior leg femora proximally not darkened; ocular area with large median and small lateral brown marks. Tibia 1 in 24 females: 4.4–5.9 (mean 5.2). Epigynum (Figs 10 B, 42 A, B) protruding, anterior plate oval, mostly dark brown except medially posteriorly, with small knob-shaped process (Fig. 11 A) near posterior margin; posterior epigynal plate very short and indistinct, light brown. Internal genitalia (Figs 41 C, 42 C, D) with pair of elongated pore plates in transversal position; with pair of lateral sclerites and complex system of membranous structures.

Etymology.

The species name is derived from the type locality; noun in apposition.

Distribution.

Known from type locality only, in Saudi Arabia, ‘ Asir Province (Fig. 13 C).

Natural history.

The spiders were found in caverns among and under boulders, often together with a representative of Smeringopus Simon, 1890 ( Araneae: Pholcidae). Both species sometimes occurred in very high densities. In one case, a ceiling of a cave was estimated to measure ~ 3 m 2 and to contain ~ 250 large (adult and penultimate instar) specimens (i. e., with average distances between specimens of ~ 10 cm) (Fig. 15). One egg sac had a diameter of 2.5 mm, and contained ~ 35 eggs. Egg diameters ranged from 0.69 to 0.71 mm.