Since Platnick (1975), the family is considered consisting of three subfamilies: the mostly Paleotropical Chediminae Simon, 1893, the purely Neotropical Otiothopinae Platnick, 1975, and the nominative subfamily Palpimaninae. The distributional peculiarities of the latter subfamily are considered below.

This subfamily differs from the Otiothopinae by possessing accessory terminal sclerites in the male bulb (which are absent in the males belonging to the latter subfamily; see Platnick 1975). The Palpimaninae can be distinguished from the Chediminae in having eight eyes with widely spaced ALE and PLE vs. two, six or eight eyes with contiguous or lacking ALE and PLE in the chedimine spiders (Zonstein and Marusik 2017). The subfamily is distributed in the Old World, where its range is limited to the Mediterranean, Sahara-Sind region (including Middle East, Gujarat and Central Asia), and the mainland Sub-Saharan Africa. The record of Palpimanus argentinus Mello-Leitão, 1927 in South America, based only on the types, has not been confirmed by later field studies, and may refer either to a sole introduced species (Platnick 1975) or, even more likely, to the incorrectly interpreted collection data (Zonstein and Marusik 2017). The Palpimaninae are divided between two sharply uneven groups of the genus rank: a species-rich Palpimanus Dufour, 1820, with 38 named species distributed throughout the entire subfamily range (WSC 2022), and a small Namibian genus Ikuma Lawrence, 1938, embracing only two species.

Palpimanus spiculosus Lawrence, 1927, by original designation.

Ikuma (I.) well differs from Palpimanus (P.) in the shape of the carapace (anteriorly narrowed, ovoidal and gently elevated from the edges to the domed central part in I. vs. round-oval and steeply edged in P.), in the clypeus (inclined in I., vertical in P.), and in the shape of the sternum (longer and visually narrower, ending posteriorly behind coxae IV in I. vs. shorter, looking subrounded, and ending posteriorly at the axes of coxae IV in P.). The whitish adpressed pubescence on the dorsal and lateral surface of the carapace is much longer and denser in I. (where it is present also on the dorsal abdomen) than in P. (where a similar pubescence is much shorter and sparser, and confined only to the carapace). The embolus is small, fragile and membranous in I. vs. relatively large, branched and with partially sclerotized structures in P. The adult females of these genera can be distinguished by the structure of the endogyne, either possessing (P.) or lacking (I.) heavily sclerotized parts.

Medium-sized to large palpimanids with carapace length ranging 4.4–5.8 in adult specimens. Dorsal body (both carapace and abdomen) densely covered with pale adpressed pubescence (Figs 1, 2); most sclerotized parts (carapace, chelicerae, sternum and abdominal scuta) finely granulated, as in Figs 1–4, 5A, B. Carapace (Figs 1C, 3A, B) narrowed anteriorly, ovoidal, with raised central part gently sloping toward edges and elevated hump between eye group and thoracic fovea. Short T-shaped thoracic fovea deeply excavated, foveal sulci poorly discernible. Clypeus moderately long. Eight eyes (Figs 1C, 3); AME largest, other eyes relatively smaller and subequal in size. AER recurved; PER nearly straight and noticeably wider than AER; both rows form wide trapezoidal figure. MOQ slightly wider than long. Chilum inconspicuous. Chelicerae about twice longer than clypeus; stridulatory ridges absent; cheliceral fang serrated; cheliceral furrow armed with several (5–6 in Ikuma larseni sp. nov.) peg teeth. Maxillae triangular. Labium long and narrow, notched anteriorly (Fig. 4B). Sternum densely granulated, covered with fine short hairs and extending backward between coxae IV (Figs 1D, 4A, D).

Figure 1. 

Ikuma spiculosa, immature holotype specimen SAM-ENW-B006293 A, B spider in dorsal and lateral view, respectively C carapace, dorsal D body, ventral. Scale bars: 1 mm.

Figure 2. 

Ikuma larseni sp.n., holotype female NMSA-SPI-26895 (A, C) and paratype male NMSA-SPI-26894 (B, D) A, B spider in dorsal view C, D same, lateral. Scale bars: 5 mm.

Figure 3. 

Ikuma larseni sp.n., holotype female NMSA-SPI-26895 (A, C, D) and paratype male NMSA-SPI-26894 (B, E) A, B carapace in dorsal view C, E eye group, clypeus and chelicerae, dorsal D same, lateral. Scale bars: 1 mm (A, D); 0.5 mm (B, C, E).

Figure 4. 

Ikuma larseni sp.n., holotype female NMSA-SPI-26895 (A, C, D) and paratype male NMSA-SPI-26894 (B, E) A, B cephalothorax and basal abdomen in ventral view C chelicerae, labium and maxillae, ventral D, E pedicel and abdominal scuta, ventral. Abbreviations: Eg epigastral plate; Le lateral extensions of scutum; Ln labial notch; Ps postgastral scuta. Scale bars: 1 mm (A, D); 0.5 mm (B, C, E).

Palps short, legs I–IV moderately long. Leg formula: 4132. Leg I robust, with considerably swollen and laterally flattened femur, with patella longer that tibia, and tarsus longer than metatarsus (Figs 1B, 2B, D). Tibia and metatarsus I with wide and dense prolateral scopula. Leg tarsi II–IV relatively short; two tarsal claws narrow and provided with several short teeth. Claw tufts well-developed (as in Fig. 7A).

Abdomen fusiform, in unsclerotised part with contrasting dorsal pattern or uniformly pale coloured. Abdominal scuta conforming a rather short pedicel tube; dorsal portion of scutum narrow, small and narrowly separated from both pedicel tube and large scoop-like ventral portion. Small spinneret group set on low mound (see Fig. 7B). AMS small, cylindrical, two-segmented; PMS and PLS reduced to a few sessile spigots in females and absent in males.

Ikuma includes two species: I. spiculosa (Lawrence, 1927) and I. larseni sp. nov.

The genus is currently known only from Namibia.

Palpimanus spiculosus: Holotype: juvenile, Namibia, Oshikoto Region, Namutoni, 18°48.5'S, 16°56.5'E, 1100 m, unspecified collector, most seemingly G.C. Shortridge (see Thomas 1926), 29.viii.1923 (SAM-ENW-B006293), seen from the full-colour and high-resolution macro-photographs kindly provided by N. Larsen. Ikuma squamata: Holotype: juvenile (or subadult specimen), the same collection data as the preceding but Ikuma (Ekuma) River Valley, approximately 18°34'S, 16°00'E, 1100 m, further details uncertain, presumably deposited in the Transvaal Museum (currently DNMNH); however, it was not found there.

There are a number of significant differences between Ikuma spiculosa and I. larseni sp. nov. It concerns the coloration of the abdomen (contrastingly bicolorous vs. uniformly pale), position of the appressed pubescence on the carapace (mostly subcentral vs. sublateral), and the relative length of interdistance AME-AME (longer than AME-ALE vs. shorter than AME-ALE).

The species was in fairly sufficient details described by Lawrence (1927, 1938). See also Fig. 1.

Oshikoto Region in northern Namibia.

The aerial distance between the type localities of Ikuma spiculosa and I. squamata, Namutoni and Ikuma River, is less than 100 km. Both are situated at the same elevation, and they adjoin the same saline depression Etosha Pan. The holotype specimens of the two species do not differ in the peculiarities and details of their pubescence and overall colouration. Judging from the original descriptions, these types can be distinguished only by their size (TL 3.6 in I. spiculosa vs. 5.5 in I. squamata). Applied to the difference in the body size between these specimens and the type series of I. larseni sp. nov. (TL 10.7–12.1), it may simply indicate that these non-adult specimens can be, respectively, a younger and an elder instars belonging to the same species. Hence, Palpimanus spiculosus Lawrence, 1927 is considered here a senior synonym of Ikuma squamata Lawrence, 1938, syn. nov.

The specific name is a patronym after Norman Larsen (Cape Town, South Africa) who kindly provided us with the macro-photographs of the preceding Ikuma species.

Holotype ♀, Namibia, Erongo Region, Namib-Naukluft National Park, Gobabeb, 23°34'S, 15°03'E, 8–9.ii.1969, B. Lamoral (NMSA-SPI-26895). Paratypes: 1♀, same collection data but 14.iv.1969, E. Holm (NMSA-SPI-26881); 1♀, same collection data but 14.iii.1970, no collector’s name indicated (NMSA-SPI-11682); 1♀, same collection data but 1–29.ii.1972, B. Lamoral (NMSA-SPI-11210); 1♂, same collection data but Narras Valley 10 km W Gobabeb, 570 m (1700 feet), 2.x.1984, C. Griswold (NMSA-SPI-26894).

Ikuma larseni sp. nov. can be distinguished from I. spiculosa by the colouration and pubescence (carapace with densest pubescence along margins vs. in subcentral part of the carapace); the new species has a uniformly pale abdomen vs. bicolorous in I. spiculosa (Fig. 2A, C cf. Fig. 1). The interdistance AME-AME is longer than AME-ALE in I. larseni sp. nov. and shorter in I. spiculosa. Since characters of I. spiculosa seem to be based on the juvenile or subadult specimens, the comparison of the copulatory organs remains impossible.

Female. NMSA-SPI-26895 (holotype).

Habitus : as in Fig. 2A, B. Colour in alcohol: carapace and chelicerae dark carmine red; maxillae, coxae I–IV and abdominal scuta light to intensely orange; palp and legs I–IV from femora to tarsi pale yellowish orange (leg I slightly darker than legs II–IV, with more noticeable difference between corresponding tibiae and metatarsi); sternum, labium and pedicel tube medium carmine red; abdomen very pale yellowish orange, dorsally with large slightly darker oval median marking; spinnerets yellowish white. Carapace and abdomen laterally covered with dense flattened and adpressed whitish pubescence. Measurements: TL 11.15. CL 4.81, CW 3.22, CyL 0.56 (0.43), Femur I L/W 2.29 (3.41/1.49). Carapace: with moderately coarse granulations (Fig. 3A). Eyes (Fig. 3B, C): AME 0.27, ALE 0.16, PME 0.13, PLE 0.13; AME-AME 0.16, AME-ALE 0.11, AME– PME 0.20, ALE-PLE 0.41, PLE-PME 0.18, PME-PME 0.31. Mouthparts: labium with slightly notched anterior edge (Ln; Fig. 4B). Legs I–IV: tarsi with paired claw tufts of dense long setae and multipectinate paired claws each armed with 8–10 teeth (Fig. 7A). Abdominal sclerites: short pedicel tube (Pt) widely funnel-shaped (Figs 4C, 5A, B); small hexagonal dorsal shield (Ds) clearly separated from and not fused with lateral sclerotized extensions (Le; Fig. 5A); epigastral plate (Eg) in intact specimen (before dissection) uniformly coloured, posterior part slightly concave; postgaster with one thin bow-shaped scutum (Fig. 4C); posterior edge nearly straight. Spinnerets as shown in Fig. 7B.

Figure 5. 

Ikuma larseni sp.n., paratype female NMSA-SPI-26881 A, B dissected, macerated and Chlorazol-tinted abdominal scuta in dorsal and ventral view, respectively C–F structures of endogyne, dorsal (inside). Abbreviations: Ds dorsal scutum; Eg epigastral plate; Ft fine threads; Gg grape shaped glands; La lateral apophyse of endogynal fold; Le lateral extensions of scutum; Pt petiolar tube; Rf basolateral fold of endogyne; Rs membranous sac like part of receptacle. Scale bars: 0.5 mm (A, B); 0.25 mm (C, D); 0.1 mm (E, F).

Copulatory organs : as in Figs 5C–F, 6. Endogyne weakly sclerotized (unlike partially heavy-sclerotized one in Palpimanus spp.); main supporting structure, wide trapezoidal endogynal fold (Rf), carries two lateral apophyses (La); membranous sacs of receptacles (Rs) bell-shaped, about as long as wide, each receptacle accompanied by brushes of fine threads (Ft) and approximately 7–8 grape-shaped glands (Gg), glands with stalks about as long as head, pore glands indiscernible (seems absent).

Figure 6. 

Ikuma larseni sp.n., paratype female NMSA-SPI-26881 A–D structures of endogyne, close up dorsal (inside) view. Abbreviations: Eg epigastral plate; Ft fine threads; Gg grape shaped glands; La lateral apophyse of endogynal fold; Rf basolateral fold of endogyne; Rs membranous sac like part of receptacle. Scale bars: 0.1 mm.

Figure 7. 

Ikuma larseni sp.n., holotype female NMSA-SPI-26895 (A, B) and paratype male NMSA-SPI-26894 (C, D) A tarsus IV in retrolateral view B spinnerets, ventral C entire leg II, retrolateral D palpal segments from patella to cymbium, retrolateral. Scale bars: 0.5 mm (A, D); 0.25 mm (B); 1 mm (C).

Leg measurements : female NMSA-SPI-26895 (male NMSA-SPI-26894 in brackets):

Male. NMSA-SPI-26894 (paratype).

Habitus : as in Fig. 2C, D. Colour in alcohol: as in female, but coxae I–IV evenly orange and tarsus I pale yellow, much lighter than metatarsus I. Measurements: TL 12.37. CL 5.78, CW 3.95, CyL 0.29, Femur I L/W 1.91 (4.23/2.21). Carapace: longer, with slightly coarser granulations than in female (Fig. 3D). Eyes (Fig. 3E): AME 0.28, ALE 0.18, PME 0.15, PLE 0.14; AME-AME 0.22, AME-ALE 0.12, AME-PME 0.34, ALE-PLE 0.46, PLE-PME 0.22, PME-PME 0.35. Mouthparts: as in female (see Fig. 4B). Legs I–IV: metatarsi and tarsi armed with long ventral bristles as in female (Fig. 7C); claw tufts and dentition as in female. Abdominal sclerites: epigastral scutum with clearly darkened book-lungs; postgaster with two large long subtriangular scuta (distinguishable in form from the corresponding scuta in other palpimanids), and two pairs of dot-like scuta (see Fig. 4E).

Copulatory organs : Palp as shown in Figs 7D, 8. Femur nearly 3 times longer than wide, 1.5 times longer than cymbium and tibia, 2.3 times longer than patella; patella elongate, 1.5 times longer than wide; tibia elongate, not swollen, length/maximal width ratio ca. 1.6, subequal in length to cymbium, covered with dense and long whitish setae; cymbium about twice longer than wide; bulb droplet-shaped; tegulum as wide as long, lacking any processes (apophyses), retrolateral part of tegulum membranous; embolic division with 2 outgrowths: slightly bent spine-like chitinized embolic process (Ep), sigmoid in anterior view (see Fig. 8A), and membranous embolus (Em).

Figure 8. 

Ikuma larseni sp.n., paratype male NMSA-SPI-26894, cymbium and palpal bulb A in frontal view B same, ventrofrontal C, D same, retrolateral. Abbreviations: Em embolus; Ep embolic process. Scale bars: 0.25 mm.

In paratype females, the length of the carapace varies from 4.4 to 5.6 mm.

According to the collecting data, the specimens were obtained by sand sifting.

Known only from the type locality.

Since the only available male of Ikuma larseni sp. nov. was found partially damaged (probably when collected), we preferred to designate one of the better preserved females as the holotype.