Ninetis subtilissima Simon, 1890

Huber, Bernhard A. & Meng, Guanliang, 2025, Like grains of sand: Ninetis spiders on the Arabian Peninsula (Araneae: Pholcidae), Zootaxa 5563 (1), pp. 290-335 : 307-308

Ninetis subtilissima Simon, 1890

Figs 3A, B , 6–12 , 34A

Ninetis subtilissima Simon, 1890: 96 (♂ ♀).

Ninetis subtilissima — Simon 1893: 486, figs 487–489. Fage 1912: 155, fig. 3a (copied from Simon 1893), fig. 134. Bristowe 1938: 310, fig. 2 (copied from Simon 1893), fig. 7 (copied from Fage 1912). Huber 2000: 82, figs 310–314. Huber & van Harten 2001: 2 , figs 1–28.

Remarks. Simon (1890, 1893) described and illustrated both sexes of this species, but his male specimen(s) from Aden seem to be lost ( Huber 2000). The redescription in Huber and van Harten (2001) was based on specimens collected ~ 60 km NE of the type locality, in Jaʽar. This new material was identified as N. subtilissima with some hesitation because of a discrepancy with Simon’s (1983) figure 488: a different curvature of the ventral bulbal apophysis. There is still no topotypical material available of this species, but our new material below shows that N. subtilissima is in fact widespread along the southern Arabian Peninsula. This supports the idea that the specimens in Huber and van Harten (2001) (and those listed below) are correctly identified.

Diagnosis. Males differ from all known congeners (and the Omani Magana velox ) by combination of: pointed procursus ( Fig. 7A–C ; Huber & van Harten 2001, fig. 4; similar only in N. faro Huber and N. toliara Huber & El Hennawy ; in other species not pointed); long cheliceral apophyses wide apart ( Fig. 7G–I ; Huber and van Harten 2001, figs 5–6; similar only in N. minuta (Berland) ; in other species shorter and/or closer together); and genital bulb with pointed dorsal process ( Fig. 7D–F ; Huber & van Harten 2001, fig. 4; in other species not pointed). From geographically close and morphologically similar N. amoud sp. nov. also by absence of flattened sclerite on dorsal bulbal process (present in N. amoud sp. nov., cf. Fig. 14D–F ). Females distinguished by combination of: trapezoidal epigynum with central pocket on membranous process (pocket in other species either absent or not on membranous process) and with pair of lateral indentations ( Figs 8 , 9 , 10F ) (otherwise present only in N. russellsmithi ); internal genital sclerites almost in straight line ( Fig. 34A ) (similar only in N. samail sp. nov.; more curved in other species).

Type material. YEMEN — Aden • Eight syntypes (4– 5 adult females, others juvenile); Aden ; 12.78 °N, 45.04 °E; 10 m a.s.l., 1889; E. Simon leg.; MNHN Ar 10788 (examined by BAH in 1999) .

New material examined. OMAN — Dhofar • 3 ♀; Wadi Shalyon ; 17.1844 °N, 54.9538 °E; 350 m a.s.l.; under rocks in wadi; 1 Mar. 2018; B.A. Huber leg.; ZFMK Ar 24402 • 1 ♀, in pure ethanol; same collection data as for preceding, ZFMK Om150 .

Ad Dakhiliyah • 2 ♂, 1 ♀; Wadi Ghul , ‘site 3’; 23.2359 °N, 57.1496 °E; 1445 m a.s.l.; 15 Feb. 2018; B.A. Huber leg.; ZFMK Ar 24403 • 2 ♀, in pure ethanol; same collection data as for preceding, ZFMK Om107 .

Ash Sharqiyah South • 3 ♂, 6 ♀; Wadi Shab ; 22.8332 °N, 59.2380 °E; 90 m a.s.l.; 19 Feb. 2018; B.A. Huber leg.; ZFMK Ar 24404 • 4 ♀, in pure ethanol; same collection data as for preceding, ZFMK Om 121 • 11 ♂, 8 ♀ (1 ♂, 1 ♀ used for SEM); Wadi Tiwi; 22.8130 °N, 59.2536 °E; 35 m a.s.l.; 19 Feb. 2018; B.A. Huber leg.; ZFMK Ar 24405 • 1 ♂, 7 ♀, 11 juvs, in pure ethanol (3 female prosomata used for molecular work; 1 ♀ used for SEM); same collection data as for preceding, ZFMK Om 120 • 2 ♀; Wadi Tiwi ; 22.8169 °N, 59.2538 °E; 40 m a.s.l.; 22 Mar. 2017; B.A. Huber leg.; ZFMK Ar 24406 • 1 juv., in pure ethanol; same collection data as for preceding, ZFMK Om 28 .

Description (amendments, see Huber & van Harten 2001)

Tibia 1 in 16 males from Oman: 0.52–0.60 (mean 0.57); in 20 females from Oman: 0.50–0.64 (mean 0.60). Male chelicerae with stridulatory files consisting of ~35 ridges each, distances between ridges 1.4 µm ( Fig. 10C ). Female chelicerae without stridulatory files ( Fig. 10D ). Male gonopore with four epiandrous spigots in two pairs ( Fig. 10E ). Sexually dimorphic short vertical hairs ( Fig. 12D ) on male tibia 1 only, apparently in four rows, with ~4–14 hairs in each row. Thin metatarsal hairs present in female (one each on metatarsi 3 and 4; Fig. 12A, B ), not seen in male. Tarsal organ of leg 4 apparently non-functional. Other SEM characters as in congeners (leg cuticular plates and pores; other tarsal organs; trichobothria; chemosensory hairs; tarsal claws; spinnerets; Figs 10–12 ) .

Intraspecific distances. The genetic (K2P) distance between two sequenced specimens (from Wadi Tiwi and Wadi Ghul; geographic distance: 220 km) was 11%; no morphological differences were seen between specimens of these localities.

Distribution. Known from several localities in Yemen and Oman ( Fig. 4B ).

Natural history. Simon (1890) collected this species under stones and in the cracks of rocks (“sous les pierres et dans les fissures des rochers”). The specimens reported in Huber and van Harten (2001) were shaken from Sorghum ( Sudan grass) in a garden in town. The newly collected specimens from Oman were collected under rocks and in leaf litter. At Wadi Shalyon, N. subtilissima was found together with N. marnif sp. nov., but in slightly different microhabitats: while N. marnif sp. nov. was found under rocks lying on sandy soil, N. subtilissima was found in a rocky area without sand. In Wadi Ghul, the spiders were found under small stones at the base of a large rock used by goats as a shelter ( Fig. 5A ). In Wadi Shab and Wadi Tiwi, the species was extremely abundant in the shaded leaf litter of mango trees at the trailside/roadside ( Fig. 5B ). Simon (1890) noted that egg sacs usually contained only 2– 3 eggs. Four newly collected egg sacs contained 5– 8 eggs, with an egg diameter of 0.39–0.44.

Figures

FIGURE 3. Ninetis Simon, live specimens. A, B. Ninetis subtilissima Simon, male from Oman, Wadi Ghul and female with embryos from Oman, Wadi Shab. C, D. Ninetis amoud Huber sp. nov., male from Saudi Arabia, NW of Al Fatiha, female from Saudi Arabia, S of Habeel. E, F. Ninetis samail Huber sp. nov., male and female from Oman, near Samail. G, H. Ninetis marnif Huber sp. nov., male and female with eggs from Oman, near Marnif. Scale line: 1 mm (all at same scale). Photos BAH.

FIGURE 4. Known distribution of Ninetis Simon. A. Distribution of the entire genus. B. Distribution of Ninetis on the Arabian Peninsula.

FIGURE 5. Typical habitats of Ninetis Simon on the Arabian Peninsula. A, B. Oman, Wadi Ghul and Wadi Tiwi (N. subtilissima Simon). C, D. Saudi Arabia, SW of Mecca and NW of Al Fatiha (N. amoud Huber sp. nov.). E, F. Oman, near Samail and near Al Hoota cave (N. samail Huber sp. nov.). G, H. Oman, near Marnif and Wadi Shalyon (N. marnif Huber sp. nov.).

FIGURE 6. Ninetis subtilissima Simon, 1890; male from Oman, Wadi Tiwi; ZFMK Ar 24405. Left male palp in prolateral (A), dorsal (B), and retrolateral (C) views. Abbreviations: b, genital bulb; c, coxa; f, femur; pa, patella; pr, procursus; ta, tarsus; ti, tibia; tr, trochanter. Scale line: 0.1 mm.

FIGURE 7. Ninetis subtilissima Simon, 1890; male from Oman, Wadi Tiwi; ZFMK Ar 24405. A–C. Left palpal tarsus and procursus, prolateral, dorsal, and retrolateral views. D–F. Left genital bulb, prolateral, dorsal, and retrolateral views. G–I. Chelicerae, frontal, lateral, and distal views. Abbreviations: dp, dorsal process; vp, ventral process. Scale lines: 0.1 mm.

FIGURE 8. Ninetis subtilissima Simon, 1890; females from Yemen, Ja’ar (A–E; ZFMK Ar 24427) and Oman, Wadi Shalyon (F–J; ZFMK Ar 24402). A, F. Epigyna, ventral views. B–C, G–H. Cleared genitalia, ventral and dorsal views. D–E, I–J. Internal transversal sclerites at higher magnifications. Scale lines: 0.2 mm.

FIGURE 9. Ninetis subtilissima Simon, 1890; females from Oman, Wadi Tiwi (A–E; ZFMK Ar 24405) and Oman, Wadi Ghul (F–J; ZFMK Ar 24403). A, F. Epigyna, ventral views. B–C, G–H. Cleared genitalia, ventral and dorsal views. D–E, I–J. Internal transversal sclerites at higher magnifications. Scale lines: 0.2 mm.

FIGURE 10. Ninetis subtilissima Simon, 1890; from Oman, Wadi Tiwi (ZFMK Ar 24405). A, B. Male and female prosomata, dorsal views. C, D. Male and female chelicerae, oblique frontal views. E. Male gonopore and epiandrous spigots. F. Epigynum, ventral view; arrow points at process with pocket. G, H. Left female spinnerets and right female ALS. Abbreviations: aep, anterior epigynal plate; pep, posterior epigynal plate. Scale lines: 100 µm (A, B, F), 20 µm (C, D), 10 µm (E, G, H).

FIGURE 11. Ninetis subtilissima Simon, 1890; from Oman, Wadi Tiwi (ZFMK Ar 24405). A, B. Right male palp, retrolateral and retrolateral-dorsal views. C, D. Left male palp, prolateral and prolateral-dorsal views. E. Left male palpal tarsal organ (arrow). F. Female left femur 3, retrolateral-ventral view, showing cuticular plates (arrows). G. Male right metatarsus 2, dorsal view, showing rimmed pore (arrow). H. Trichobothrium on female right metatarsus 4. Abbreviations: b, genital bulb; dp, dorsal process; pr, procursus; vp, ventral process. Scale lines: 100 µm (A–D), 10 µm (E, F, H), 2 µm (G).

FIGURE 12. Ninetis subtilissima Simon, 1890; from Oman, Wadi Tiwi (ZFMK Ar 24405). A. Thin metatarsal hair (arrow) on female right metatarsus 3, ventral-prolateral view. B. Thin metatarsal hair (arrow) on female left metatarsus 4, ventral-distal view. C. Putative chemoreceptor on male right tarsus 1, prolateral view. D. Sexually dimorphic short vertical hairs (arrows) and regular mechanoreceptors on male right tibia 1, prolateral view. E, F. Tarsal organs (and neighboring slit sensilla) on left male tarsi 1 and 2, retrolateral-dorsal views. G. Tip of female right tarsus 2, prolateral view. H. Tip of female left tarsus 4, retrolateral view. Scale lines: 10 µm (A, B, D, G, H), 2 µm (C, E, F).

FIGURE 14. Ninetis amoud Huber sp. nov.; male paratype from Saudi Arabia, NE of Wadi ‘Amoud; ZFMK Ar 24407. A– C. Left palpal tarsus and procursus, prolateral, dorsal, and retrolateral views. D–F. Left genital bulb, prolateral, dorsal, and retrolateral views; thick arrows point at distinctive flattened dorsal sclerite. G–I. Chelicerae, frontal, lateral, and distal views. Abbreviations: dp, dorsal process; vp, ventral process. Scale lines: 0.1 mm.

FIGURE 34. Female internal genitalia, transversal sclerites at same magnification. A. Ninetis subtilissima Simon, 1890; from Oman, Wadi Shalyon; ZFMK Ar 24402. B. N. amoud Huber sp. nov.; paratype from Saudi Arabia, NE of Wadi ‘Amoud; ZFMK Ar 24407. C. N. samail Huber sp. nov.; from Oman, near Samail; ZFMK Ar 24420. D. N. marnif Huber sp. nov.; from Oman, W of Al Marnif; ZFMK Ar 24424. Scale line: 0.1 mm.