Ancylodactylus kenyaensis, 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 : 106-109

Ancylodactylus kenyaensis sp. nov.

Kenya Forest Gecko

( Figures 2–3 )

Cnemaspis quattuorseriatus (part) Loveridge 1947:80.

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

Holotype. NMK-220L/2 (Field No. Chuka 2), adult male, Mt. Kenya Forest, Chuka Block , Meru, Tharaka-Nithi County, Kenya (00.30101° S, 37.58712° E; 1680 m), collected 9 May 2019 by Patrick K. Malonza & Joash O. Nyamache.

Paratypes. NMK-220L/1 (Field No. Chuka 1), adult female, Mt. Kenya Forest, Chuka Block , Meru, Tharaka-Nithi Couinty , Kenya (00.30463° S, 37.56624° E; 1862 m), collected 9 May 2019, by Patrick K. Malonza & Joash O. Nyamache; NMK-L3888/2, adult female, Karura Forest , Nairobi County, Kenya (01.24068° S, 36.84965° E; 1663 m), collected 16 February 2017 by Patrick K. Malonza, Washington Wachira & Vincent Muchai; NMK- L3131/3, adult male, Ngaya Forest , Nyambene Hills, Meru County, Kenya (00.371667° N, 38.02114° E; 1232 m), collected 21–27 April 2008 by Patrick K. Malonza & Vincent Muchai; NMK-L3186/2, adult female, Chogoria Forest Block-Meru, Mt. Kenya Forest, Tharaka-Nithi County, Kenya (00.23914° S, 37.58914° E; 1724 m), collected 6 March 2009 by Patrick K. Malonza, Joash Nyamache & Vincent Muchai .

Other locality. Blue Post Hotel-Thika rock outcrops and forest patch (01.02583°S, 37.06706° E; 1459 m elevation). Observed, but not collected in July 2019 by Patrick K. Malonza.

Diagnosis. A large Ancylodactylus , (to 60 mm SVL in males and 65 mm in females). Dorsal scalation heterogeneous, minute granular scales with enlarged, irregularly-arranged, rounded tubercles in 11–14 irregular longitudinal rows at midbody, extending posteriorly from the nape or occiput. Limbs and digits long, with enlarged basal lamellae under and proximal to penultimate interphalangeal joint (6 under digit IV). Original tail slightly longer than SVL; dorsal scalation of tail lacking tubercles; median subcaudal scales with alternating pattern of single enlarged scales and pairs of somewhat smaller scales. Male precloacal pores in a single continuous row of eight. Dorsal pattern of chevrons, broken bands and spots on a light brown to grayish-brown background. Ventral coloration whitish with faint darker markings on throat and trunk.

Comparisons with Congeners. Ancylodactylus kenyaensis 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 , A. petrodroma , A. occidentalis , A. spinicollis , A. alantika , A. kituiensis sp. nov., and A. spawlsi sp. nov. by lacking tubercles on the post-pygal (autotomic) portion of the tail dorsum. It has substantially more longitudinal rows of dorsal trunk tubercles (11–14) than A. quattuorseriatus , A. dickersonae , A. dilepis , A. mathewsensis sp. nov., A. laikipiensis sp. nov., A. spawlsi , sp. nov., and A. chyuluensis sp. nov. (maximum 6 rows), and a greater maximum number than all remaining species (8–12 rows). It possesses a lower number of precloacal pores (8) than A. africanus (9–12), A. barbouri (14), A. alantika (11), and A. gigas (15–16) and a higher number than A. mathewsensis sp. nov., A. laikipiensis sp. nov., and A. spawlsi , sp. nov. (6–7), It may also be distinguished in having an enlarged median series of subcaudals consisting of alternating single and paired scales from A. africanus , A. dilepis , A. gigas , A. alantika , A. mathewsensis sp. nov., A. laikipiensis sp. nov., A. spawlsi , sp. nov., and A. chyuluensis sp. nov. (all with a single median row of enlarged subcaudals) and from A. spinicollis , A. petrodroma , and A. occidentalis (irregular subcaudals). In lacking any yellow or orange ventral coloration A. kenyaensis sp. nov. may be distinguished from A. africanus , A. koehleri , A. dilepis , A. spinicollis , A. petrodroma , A. occidentalis , A. alantika , A. mathewsensis sp. nov., A. laikipiensis sp. nov., and A. spawlsi , sp. nov. This last feature also distinguishes the new species from A. elgonensis , which it resembles in size and most features of scalation. A. kenyaensis sp. nov., with a maximum size of 65 mm SVL, is the largest member of its genus in Kenya and is at least 50% larger than A. barbouri , A. uzungwae , A. quattuorseriatus , A. dickersonae , A. dilepis , A. mathewsensis sp. nov., A. laikipiensis sp. nov., A. spawlsi , sp. nov., and A. chyuluensis sp. nov.

Description of holotype. Specimen generally in good condition. Body somewhat dorsoventrally flattened ( Figs. 2 , 3 ). Measurements: SVL = 55.0; TAL = 60.0; HL = 15.8; HW = 10.3; OD = 3.4; SE = 7.0. Head elongate (HL/SVL = 0.29), moderately wide (HW/HL = 0.65), only weakly depressed, distinct from the neck, loreal region flattened, canthus rostralis prominent. Scales on snout and loreal region much larger than scales of interorbital region and crown. Eyes relatively small (OD/HL = 0.21), ear opening oval; two large internasals. 7 infralabials and 7 supralabials. Mental scale triangular; 3 postmentals, the outer larger and in contact with the first infralabials and mental; 5 post-post mentals.

Dorsal pholidosis heterogeneous; minute juxtaposed granules interspersed with enlarged tubercles, several times size of adjacent granular scales, arranged in approximately 12 irregular longitudinal rows at midbody ( Fig 2B ). Tubercles broad, rounded, conical to weakly keeled; those on nape and shoulders smaller than on more posterior portions of trunk; rows becoming more irregular in sacral region and on flanks. Scattered tubercles on occipital and temporal regions smaller than those on body. Ventral scales larger than dorsal, smooth, imbricate, slightly larger in precloacal and femoral regions than on chest and belly; approximately 13 at midbody. Fore-and hind limbs relatively long, slender, covered by granular to slightly enlarged sub-imbricating scales, the latter chiefly on the preaxial surfaces. Prominent axillary pockets present. All digits moderately long and slender, strongly clawed; penultimate phalanx of all digits curved and very slender, arising angularly from the distinctly wider basal toe pad; six wide basal lamellae and 10 narrow distal lamellae under digit IV of pes ( Fig. 2D ). Enlarged basal lamellae on digits of pes: I:1, II:4, III:6, IV:6, V:4. Male precloacal pores in a single continuous row of eight ( Fig 2C ). Hemipenial bulge prominent ( Fig. 2C , 3B ), a single prominent, pale postcloacal spur on each side of the vent. Tail slightly depressed, slightly longer than SVL (TAL 109% SVL), tail dorsum covered in small, mostly uniform subimbricate to juxtaposed squarish to oval scales ( Fig. 2E ), lacking tubercles throughout; midventral subcaudal scales with a single enlarged scale alternating with a pair of smaller scales ( Fig. 3B ).

Coloration (in preservative). Dorsum light grayish-brown with dark blotches and a series of faint chevron marks ( Fig. 2A ). Dorsolateral tubercles light brownish. Crown of head brown with some darker marks; infralabials and supralabials with alternating light and dark markings. Limbs brown with slightly darker transverse mottling or bands; dark banding on digits. Tail light gray to brown with faint diamond/chevron marks. Body venter whitish, tail venter light cream, throat whitish.

Coloration (in life). In life, during the day, the dorsal color is predominantly light brown to grayish brown, with a series of irregular, yellowish- or pinkish-brown spots or diamond-shaped marks. Additional longitudinal rows of yellowish markings in paravertebral position and on flanks; collectively the markings form a broken chevron-like pattern on the dorsum ( Fig. 3A ). The original tail is mainly brownish with about 6–7 yellowish-brown to whitish diamond-shaped marks formed by the fusion of the paravertebral markings continuing from the trunk. The head is light brownish with some dark scattered markings yielding an irregular, ill-demarcated, reticulated pattern. Dorsal color may occasionally be affected by the substrate on which the gecko is resting and/or external stimuli like prevailing weather conditions. Throat and belly are largely off-white, becoming more grayish under the tail and under distal portions of the limbs and feet. Some faint speckling of throat and chest ( Fig 3B ). Post-cloacal spur bright white or yellow ( Figs. 3A, 3C ).

Variation. Mensural data for the type series is given in Table 1 . All paratypes are in generally good condition and all retain at least partial tails. Paratypes generally similar to holotype in most aspects. In some individuals a mixture of yellow, dark brown and pale brown granules may yield a speckled appearance ( Fig. 3C ). The dorsal markings may fuse to form more complete chevrons or transverse bands, and the vertebral spots or diamonds may fuse to yield a more-or-less continuous vertebral stripe ( Fig. 3C ). No clear sexual dichromatism but females achieve slightly larger sizes than males. Males have a continuous single series of 8 precloacal pores ( Table 1 ).

Etymology. Named for the Mt. Kenya region and the central Kenya highlands where the species occurs.

Natural History. This is a diurnal arboreal gecko found mainly on tree trunks ( Fig. 3B ) and fallen logs. In the Karura Forest, Mt. Kenya Forest and Ngaya Forest individuals were found mostly in tree trunk crevices. At the Blue Post Hotel-Thika riverine forest they were found in crevices and caves in rock outcrops. They are alert and rapidly dash into their retreats and at most localities they occur microsympatrically on tree trunks with the Mt. Kilimanjaro Forest Lizard, Adolfus kibonotensis (Lönnberg) . In the Kirimiri Forest-Mt. Kenya they are also microsympatric with their dwarf congener, Ancylodactylus spawlsi sp. nov. The holotype and some other specimens were infested with trombiculid mites, most occupying the axillary pockets, but also the lateral surfaces of the neck ( Figs. 3A–C ).

Habitat and Distribution. This is a montane forest species occurring in the central Kenyan highlands in the Mt. Kenya Forest Reserve (Chogoria and Chuka Forest Blocks, Kirimiri Forest-Runyenjes), Karura Forest-Nairobi, Nyambene Hills (Ngaya and Keiga Forests), and the Blue Post Hotel forest patch in Thika. We expect it to be present in similar sites throughout the central montane region. All known localities are at elevations of approximately 1200–2000 m.

Figures

FIGURE 2. Ancylodactylus kenyaensis sp. nov. A) Dorsal view of holotype, NMK-220L/2. Scale bar = 10 mm. B) Dorsal view of holotype trunk at midbody. C) Precloacal region of holotype showing a series of 8 precloacal pores (arrows mark the lateralmost pores). D) Ventral view of right hind foot of paratype NMK-220L/1. E) Dorsum of tailbase of holotype.

FIGURE 3. Ancylodactylus kenyaensis sp. nov., in life. A) Holotype (NMK-220L/2), adult male, dorsal view, note trombiculid mite infestation. B) Holotype venter showing lack of bright pigmentation. C) Adult female paratype (NMK-220L/1); D) Tree trunk microhabitat of A. kenyaensis in Chuka Forest, Meru South, Thiraka-Nithi County, Kenya.