Description of a new genus and three new species of the family Palpimanidae (Arachnida, Araneae) from Kenya

A new genus and three new species of the spider family Palpimanidae Thorell, 1870 from Kenya are described. Sceliscelis Oketch & Li, gen. nov. is close to Sarascelis Simon, 1887 and Scelidocteus Simon, 1907 but differs in the structure of the male palp. The new species reported are Sceliscelis marshi Oketch & Li, sp. nov., Scelidocteus taitave Oketch & Li, sp. nov., and Hybosida machondogo Oketch & Li, sp. nov. Sceliscelis marshi sp. nov. is described from males and females collected from Tsavo in south Kenya. Scelidocteus taitave sp. nov. can be distinguished from other congeners, as well as from the morphologically similar Scelidomachus socotranus Pocock, 1899, by the shape of the palpal “conductor”. Hybosida machondogo sp. nov. differs from other six-eyed Hybosida spp. by possessing rudimentary posterior median eyes.


Introduction
Palpimanidae Thorell, 1870 is a small family of araneophagous spiders recognized by the coriaceous carapace, haplogyne genitalia, two spinnerets and especially by the first pair of legs with dorsally enlarged femora and well-developed prolateral scopula on the tibia, metatarsus and tarsus. A total of 152 species in 18 genera are distributed in tropical and subtropical zones worldwide, absent only in the Nearctic and Australia (Li 2020). Within Africa, the family is known to include 56 species belonging to 12 genera (WSC 2020), although some of these species are certainly misplaced in the family (Zonstein and Marusik 2013;Zonstein et al. 2018).
More than 800 spider species and subspecies belonging to 55 families are known from Kenya (WSC 2020). However, Palpimanidae have not been thoroughly studied. Up to now, only three species have been described: Scelidocteus incisus Tullgren, 1910, Hybosida lesserti Berland, 1920 and H. scabra Simon & Fage, 1922. In this paper, one new genus and three new species of palpimanid spiders found during the examination of spiders collected in various protected sites in Kenya are described.

Materials and methods
All spiders were preserved in 95% alcohol. Specimens were examined and measured using a LEICA M205C stereomicroscope. Images were captured using an Olympus C7070 wide zoom digital camera mounted on an Olympus SZX12 dissecting microscope or on an Olympus BX51 compound microscope. Male and female copulatory organs were dissected, and the specimens were then photographed on glass slides fitted with cotton wool to ensure a white, uniform background. Digital images were prepared using Helicon Focus version 6.0 image stacking software and then edited using Adobe Photoshop CS4 version 11.0.0.
Leg lengths and palp segments are given in the following sequence: total (femur, patella, tibia, metatarsus, tarsus). Internal structures of the genitalia were illustrated after being cleared in lactic acid, then placed in alcohol for a few minutes. Measurements are given in millimeters. Holotypes and paratypes are deposited in the National Museums of Kenya (NMK), Nairobi, Kenya.
Abbreviations. AER -anterior eye row, ALE -anterior lateral eyes, am -accompanying membrane, AME -anterior median eyes, co -"conductor", ch -receptive chamber, cy -cymbium, ds -dorsal portion of scutum, em -embolus, Ft -fine threads, Gr -grape-shaped glands, hle -hook-like extension, MOQ -median ocular quadrangle, pe -palm-like embolic extension, PER -posterior eye row, PLE -posterior lateral eyes, PME -posterior median eyes, Re -rigid extensions of posterior wall of epigastric fold, rt -retrolateral thorn, sco -scopula, Sr -saclike receptacle. Etymology. This genus possesses some characteristics that are also found in Sarascelis Simon, 1887 andScelidocteus Simon, 1887, such as the dentate segments of leg I (which include at least the dorsal surface of the coxa and basal part of the femur) and the spiral embolus. The name is a combination of "Sceli" from Scelidocteus and "Scelis" from Sarascelis. The gender is feminine.
Diagnosis. The new genus closely resembles Sarascelis in general appearance by having much larger AMEs ( Fig. 1A; also see Jézéquel 1964, fig. 5a-c, Zonstein andMarusik 2013;figs 5, 6). It can, however, be distinguished from Sarascelis, Scelidocteus and the close ally Steriphopus Simon, 1887 by (1) having a greatly extended bulb (vs. the more or less bulky palpal structures of Sarascelis and Steriphopus) (2) the large AMEs (Steriphopus has considerably smaller AMEs) (3) the shape of the thoracic fovea, which is an elongated Ω-shape in Sceliscelis (vs. a longitudinal slit or anchor-like in Sarascelis and Scelidocteus) (4) the presence of a hook-like extension at the distal end of a sword-like "conductor" (vs. extension absent in other members of the family) (5) the poorly developed scopula on metatarsus and tarsus I (6) the rugose carapace in Sceliscelis gen. n. (vs. smooth or finely rugose in Sarascelis, Scelidocteus and Steriphopus) (see Zonstein and Marusik 2013). Females of Sceliscelis can be distinguished from those of Sarascelis and Scelidocteus by the wavy, rigid extension of the genital area and by a pair of divergent sac-like receptacles.
Description. Medium-sized. Carapace dome shaped, coarsely granulated and hairless, medially elevated, fovea longitudinal, open posteriorly (elongated Ω-shape). Eight eyes, MOQ trapezoidal; AME largest, about 3 times as large as PME; ALE, PLE and PME subequal to each other. AER straight. Labium triangular, notched, longer than wide but broader at base. Chelicerae directed ventrally, 2 times longer than clypeus, granulate. Endites trapezoidal, about 1.5 times longer than wide. Abdomen clay yellow, oval and covered with short, gray setae in both sexes. Femur of male palp slender, longer than wide, patella shorter than "conductor". Cymbium with setae, pointed at tip and indented (prolateral view). Embolus spiral, with accompanying membrane and a silvery, palm-like embolic extension. "Conductor" sword-shaped, longer than wide, slightly longer than embolus. Endogyne wavy anteriorly, forming a rigid epigastric wall.
Composition. This genus currently includes only the type species. Etymology. This species is named after Mr. Brian Marsh OBE, the founder of the Marsh Christian Trust Awards for Ecologists in Africa, which the third author was awarded in 2019; noun (name) in genitive case.
Distribution. This species is currently known only from the type locality.

Genus Scelidocteus Simon, 1907
Type species. Scelidocteus pachypus Simon, 1907, by subsequent designation. Notes. All seven described species of this genus are endemic to Africa, the majority of them in West and Central African countries. Scelidocteus taitave sp. nov. is the first species to be recorded from Kenya and East Africa (WSC 2020). Scelidocteus resembles Scelidomachus and Chedima Simon, 1873 in general appearance, especially in having an anteriorly blunt (not rounded) carapace with pronounced, obtuse anterolateral corners, but can be distinguished from Chedima by the uniformly colored abdomen (vs. spotted) with short gray setae and the eye shape and arrangement (MOQ in Chedima is longer than wide, whereas it is subquadrate in Scelidocteus). Etymology. The specific name is a combination of Taita and Taveta, the county from which the specimens were collected; noun in apposition.
Distribution. This species is currently known only from the type locality.

Genus Hybosida Simon, 1898
Type species. Hybosida lucida Simon, 1898, by monotypy. Diagnosis. All four described species of this genus have six eyes, PMEs are absent (Simon 1898, Platnick 1979, Saaristo 2010. H. dauban Platnick, 1979 andH. lucida Simon, 1898    Etymology. The specific name is a combination of two Swahili words "macho", meaning eyes, and "ndogo'', meaning small, referring to the indiscernible posterior median eyes of this species. Diagnosis. Like other members of Chediminae, Hybosida machondogo sp. nov. possess contiguous lateral eyes and accessory structures of the male palp (see Zonstein and Marusik 2013, figs 1-9;Zonstein et al. 2018). It closely resembles H. lesserti by having (1) a more compact carapace with the cephalic part narrowed (2) an elevated carapace with a steep posterior slope (3) a strongly convex carapace in lateral view and (4) poorly developed scopula on both the metatarsi and tarsi of legs I (see Berland 1920, figs 128, 131). However, H. machondogo sp. nov. differs from H. lesserti and other members of this genus by having (1) 8 eyes instead of 6, (2) a bulb with relatively long, sharp and less curved apophysis (vs. strongly curved in H. lesserti).
Female. Unknown. Distribution. This species is currently known only from the type locality.
Notes. This species is peculiar because it is at odds with the initial description of the type species of the genus Hybosida, which states that the number of eyes is 6. It does, however, resemble Hybosida in the shape of the carapace, the fovea and the general structure of the male palp. It is therefore treated as belonging to this genus.