Ancylodactylus mathewsensis, Malonza & Bauer, 2022

Malonza, Patrick K. & Bauer, Aaron M., 2022, Resurrection of the African gecko genus Ancylodactylus Müller, 1907 (Squamata: Gekkonidae) and description of six new species from Kenya, Zootaxa 5141 (2), pp. 101-139 : 116-120

Ancylodactylus mathewsensis sp. nov.

Mathews Range Forest Gecko

( Figures 7–8 )

Cnemaspis dickersonae (part) Spawls et al. 2018:80.

Holotype. NMK-L3375/1, adult male, Mathews Range Forest at Mugur area, Namunyak Conservancy, Samburu County, Kenya (01.25558° N, 37.22130° E; 1768 m), collected 9 June 2010 by Patrick K. Malonza & Justus Ochong.

Paratypes. NMK-L3375/2, adult female and NMK-L3375/4, adult male, same data as holotype; NMK-L3368/3, adult female, Mathews Range Forest , Lemurit area, Samburu County, Kenya (01.17122° N, 37.34365° E; 1469 m), collected 4 June 2010 by Patrick K. Malonza & Justus Ochong .

Diagnosis. A small-sized Ancylodactylus , both sexes with a maximum SVL of approximately 40 mm. Dorsal scalation mostly homogeneous with smooth, granular scales. Trunk with a few small, scattered tubercles, particularly in the sacral region; may otherwise be atuberculate, or there may be a single row of tubercles on each flank. Limbs and digits long, with enlarged basal lamellae under and proximal to penultimate interphalangeal joint (4 under digit IV). Original tail slightly longer than SVL. Tail dorsum distal to the pygal portion of the tail atuberculate; median subcaudal scales transversely widened and in a single row. Male precloacal pores in a single continuous row of 6–7. Dorsal pattern of pale fleurs-de-lis and spots on a yellowish- to grayish-brown background; diamond-shaped markings on tail. Ventral coloration of trunk yellow, tail venter orange, chin and anterior throat whitish with diffuse dark longitudinal stripes. whitish with faint darker markings on throat and trunk.

Comparisons with Congeners. Ancylodactylus mathewsensis sp. nov. may be distinguished from A. spinicollis and A. petrodroma in lacking an enlarged preaxial metatarsal scale and from these two species plus A. alantika in having a series of flattened, rectangular lamellae subtending the second and third phalanges of the pedal digits, rather than single enlarged, rounded scale (plaque of Perret 1986) at the penultimate joint of each digit. It is distinguished from A. uzungwae , A. quattuorseriatus , A. dickersonae (but see Spawls et al. 2018), A. petrodroma , A. occidentalis , A. spinicollis , A. alantika , A. kituiensis sp. nov., and A. spawlsi sp. nov. by lacking tubercles on the postpygal (autotomic) portion of the tail dorsum. It has fewer rows of dorsal trunk tubercles (0–2) than all its congeners except A. dickersonae (0–6 fide Perret 1986; 0–4 fide Spawls et al. 2018), A. laikipiensis sp. nov. (0), A. spawlsi , sp. nov. (0–2), and A. chyuluensis sp. nov. (2). It possesses a lower number of precloacal pores (6–7) than A. africanus (9–12), A. barbouri (14), A. dilepis (8), A. petrodroma (8–12), A. occidentalis (8–12), A. alantika (11), A. gigas (15–16), A. kenyaensis sp. nov. (8), A. kituiensis sp. nov. (8–13), and A. chyuluensis sp. nov. (8). It may also be distinguished in having an enlarged single median series of subcaudals in contrast to A. spinicollis , A. petrodroma , and A. occidentalis (irregular subcaudals), A. elgonensis , A. barbouri , A. uzungwae , A. kenyaensis sp. nov., and A. kituiensis sp. nov. (alternating single and paired scales), and A. africanus , A. quattuorseriatus , A. dickersonae , A. koehleri , A. alantika , A. laikipiensis sp. nov., A. spawlsi , sp. nov., and A. chyuluensis sp. nov. (single row of median subcaudals, but without midventral scales transversely widened or not uniform throughout). In having yellow on most of the venter it differs from A. barbouri , A. uzungwae , A. quattuorseriatus , A. gigas , A. kenyaensis sp. nov., and A. kituiensis sp. nov. Among Kenyan congeners A. mathewsensis sp. nov. (40 mm maximum SVL) is significantly smaller than A. kenyaensis sp. nov. (maximum SVL 65 mm) and A. kituiensis sp. nov. (maximum SVL 50 mm) but marginally larger than A. laikipiensis sp. nov. (maximum SVL 35 mm), and substantially larger than A. spawlsi , sp. nov. (maximum SVL 30 mm), and A. chyuluensis sp. nov. (maximum SVL 28 mm).

Description of holotype. Specimen generally in good condition. Body somewhat dorsoventrally flattened, tail curved ( Fig 7 ). Holotype measurements: SVL = 37.3; TAL = 41.0; HL = 11.0; HW = 7.4; OD = 2.0; SE = 5.0. Head elongate (HL/SVL = 0.29), moderately wide (HW/HL = 0.67), somewhat depressed, and distinct from the neck, loreal region flattened, canthus rostralis prominent. Scales on snout and loreal region domed, much larger than scales of interorbital region and crown. Eyes small (OD/HL = 0.18), ear opening oval; two large internasals, 6 infralabials and 6 supralabials. Mental scale subtriangular with truncated posterior apex; 3 postmentals, the outer pair larger and in contact with the first infralabials, separated from one another by smaller, hexagonal median postmental and mental; 5 post-post mentals.

Dorsal pholidosis mostly homogenous, covered by minute granular scales. Very few, scattered, slightly enlarged scales (approximately twice the diameter of typical granules) on dorsum of trunk; neither bearing keels nor forming discrete longitudinal rows ( Figs. 7A, 7B ). A single row of enlarged, smooth, conical tubercles may be present along each flank ( Fig. 8A ). Ventral scales larger than dorsal, smooth, imbricate, slightly larger in precloacal and femoral regions than on chest and belly; approximately 15 at midbody. No distinct ventrolateral folds; gular region with still smaller sub-imbricate scales, those on the lateral aspect of neck granular. Fore-and hind limbs relatively long, slender, covered by granular to slightly enlarged sub-imbricating scales, the latter chiefly on the preaxial surfaces. All digits moderately long and slender, strongly clawed; penultimate phalanx of all digits curved, arising angularly from distal portion of the distinctly wider basal toe pad; four wide basal lamellae, the distalmost much larger than the more proximal, and 10 narrow distal lamellae under digit IV of pes ( Fig. 7C ). Enlarged basal lamellae on digits of pes: I:1, II:3, III:4, IV:4, V:3.

Male precloacal pores in a single continuous row of 7. Hemipenial bulge prominent ( Fig. 7D , 8C ), a single prominent, postcloacal spur on each side of the vent ( Fig. 7A , 8C ). Tail (partly regenerated) slightly depressed, slightly longer than SVL (TAL 109% SVL), original portion of tail dorsum covered in small, mostly uniform juxtaposed squarish to oval scales ( Fig. 7E ); segmentation of tail obscure. Sacral region with two pairs of adjacent, enlarged, rounded tubercles followed by a single pair of similar tubercles over the pygal portion of the tail. The post-pygal portion of the tail bears no dorsal tubercles ( Fig. 7E ). Scales of regenerated portion of tail sub-imbricate, larger than those on original portion, somewhat irregular in size and shape. Transversely enlarged midventral subcaudal scales in a single row ( Fig. 8C ).

Coloration (in preservative). Dorsum dark grayish-brown with a series of pale brown chevrons or diamondshaped marks along the back, partly running together to form a pale vertebral stripe of varying width from the occiput to the tail base. Margins of individual chevrons partly demarcated by scattered dark flecks. Crown of the head grayish-brown; infralabials and supralabials pale with dark stippling. Limbs grayish-brown with slightly darker transverse mottling or banding; dark bands on all digits. Tail dorsum dull yellowish-brown with a series of pale diamond-shaped markings, each flanked anteriorly by a pair of dark brown markings. Pattern of regenerate mottled light and dark brown. Body venter cream-white, subcaudal surfaces light cream.

Coloration (in life). Based on specimens photographed in life (see Fig. 8 ). In life, during the day, the dorsal color is mainly shades of pale yellowish-brown to dark grayish-brown, with a middorsal series of paler markings, each resembling a fleur-de-lis that partly overlaps the next most anterior marking. Dorsal color may be affected by the substrate on which the gecko is resting and/or external stimuli, such as prevailing weather conditions. The dorsal markings may be cream colored ( Fig. 8A ) or reddish-brown ( Fig. 8B ) and have a darker central marking and are outlined anteriorly by a thin dark brown border. The darkest portions of the dorsum are in paravertebral position just anterior to the lateral portions of the chevrons/fleurs-de-lis. A series of pale, rounded markings, roughly the same color as the dorsal markings run along the flanks. These are each partly surrounded by darker brown irregular borders and may be centered on the flank tubercles, if present.

The head bears the same colors as the dorsum, with a darker background bearing roughly symmetrical paler markings, including an occipital blotch. A diffuse brown line runs anteriorly from the eye and meets its counterpart on the posterior portion of the snout. From the posterior margin of the orbit a brown line passes above the ear to meet its counterpart on the nape, behind the pale occipital blotch and another passes posteroventrally towards the posterior end of the jaw. The labial scales exhibit alternating light and dark markings. Limbs mottled to banded with the same colors as the trunk; digits with well-demarcated alternating light and dark bands. The dorsal pattern continues onto the tail with the pale markings becoming distinctly diamond-shaped. 8–9 such markings on the original tail, each flanked anteriorly by a thick, irregular dark brown border and with a narrow, dark brown mid-vertebral line in its center.

The venter is bright yellow from the posterior throat region to the pygal portion of the tail, with the most intensely pigment region on the neck. The anterior throat is whitish and bears a series of diffuse, dark longitudinal lines; the yellow coloration of the rest of the venter pales to a wash on the posterior throat, mostly fading away by the widest portion of the head, although traces of pale yellow extend forward along the edge of the jaws. The undersides of the limbs are also bright yellow, with the palms and soles grayish or mottled gray and yellow. The subcaudal surface is a bright orange, especially intense on the scales bordering the transverse subcaudal plates. At the base of the post-pygal portion of the tail there is a transition zone from yellow to orange within which the scale centers bear the latter color and their margins the former ( Fig 8C ). The ventral surface of the regenerated portion of the tail is a dull orange, fading distally.

Variation. Mensural data for the type series is given in Table 4 . Paratypes generally resemble the holotype and all are in good general condition. Variation in life color is discussed above. There is no evidence of sexual dimorphism in size or color. The male paratype has a single continuous series of 6 precloacal pores.

Etymology. Named for the Mathews Range, the type locality of this taxon.

Natural History. This is a diurnal, scansorial gecko found mainly on rock outcrops with crevices, as well as on trees. In the Mathews Range Forest it is found along with the Mathews Range Forest Lizard, Adolfus mathewsensis (Greenbaum, Dowell-Beer, Hughes, Wagner, Anderson, Villanueva, Malonza, Kusamba, Aristote & Branch) , Kenya Dwarf Gecko Lygodactylus keniensis Parker, Striped Skink Trachylepis cf. striata (Peters) , Five-lined Skink Trachylepis quinquetaeniata (Lichtenstein) , and Kenya Red-headed Rock Agama Agama lionotus Boulenger. It is agile and on rock outcrops, when disturbed, immediately dashes into a crevice.

Habitat, Distribution and Conservation Status. This is dryland, hilltop montane forest species endemic to the Mathews Range (Ol Doinyo Lenkiyo), a chain of hills with several peaks, the highest being around 2375 m. The range is isolated by small valleys from other geologically similar mountain blocks: to the south Mt. Warges (Uarges) 2688 m and the Ndoto Mountains (2637 m), and Mt. Nyiru or the Nyiru Range (Ol Doinyo Nyiro) at 2752 m to the north. They are all within the Precambrian basement rock system. Other peaks with hill-top montane forests in the region are the volcanic Mt. Kulal (2285 m) and Mt. Marsabit (1707 m). These neighboring mountain blocks may harbor this Ancylodactylus species or perhaps their own endemic ones, as they are all isolated to some extent. However, they have not yet been surveyed. The Mathews Range rises to 2375 m from the surrounding Acacia-Commiphora arid bushlands at about 950 m. Mid-elevation dry forest starts at around 1350 m and it is from this elevation upwards to around 1800 m that the species has been recorded, although they may occur even higher. The lower forest is dominated by Croton megalocarpus and Podocarpus species in the higher elevations. During the collection period (start of the long dry season) the species was relatively common in suitable sites.

Figures

FIGURE 7. Preserved specimen of holotype of Ancylodactylus mathewsensis sp. nov., NMK-L3375/1.A) Dorsal view of entire specimen. Scale bar = 10 mm. B) Trunk dorsum, showing heterogeneous granular scalation. C) Ventral view of right hind foot. D) Precloacal region showing a series of 7 precloacal pores (arrows mark the lateralmost pores). E) Dorsum of tail base showing rounded tubercles on pygal portion of tail only. Post-pygal (autotomic) portion of tail without tubercles.

FIGURE 8. Ancylodactylus mathewsensis sp. nov.. A) Living holotype (NMK-L3375/1) and B) paratype (NMK-L3368/3) in dorsal views showing the typical fleurs-de-lis dorsal pattern typical of this and several other Kenyan Cnemaspis. C) Ventral view of male holotype showing the typical contrasting yellow trunk and limb venter and orange subcaudal surface. Note the transversely widened midventral subcaudal scales in a single row. Photos © P.K. Malonza.