Hemidactylus hannahsabinae, Ceríaco & Agarwal & Marques & Bauer, 2020

Ceríaco, Luis M. P., Agarwal, Ishan, Marques, Mariana P. & Bauer, Aaron M., 2020, A correction to a recent review of the genus Hemidactylus Goldfuss, 1820 (Squamata: Gekkonidae) from Angola, with the description of two additional species, Zootaxa 4861 (1), pp. 92-106 : 95-99

Hemidactylus hannahsabinae sp. nov.

( Figs. 1–3 )

lsid: http://zoobank.org:act: 62924636-62F8-43AA-B686-9A47B8DC2FA2

Hemidactylus nzingae [part]: Ceríaco et al. (2020: 48)

When describing H. nzingae, Ceríaco et al. (2020) considered specimens from Dande, Malanje Province (AMNH 47783, 51960, 51961) and Pavalange, Bié Province (ANSP 32189; Fig. 1 ) deposited in the AMNH and ANSP collections, as part of their newly described species. The specimen from Pavalange (ANSP 32189) was even included in the paratype series. These misidentifications were partly explained by the considerable overlap of scale counts and distribution range ( Table 1 ). However, a careful reevaluation of these specimens established that they are not conspecific with the type series of H. nzingae . All male specimens of H. nzingae present a well-marked series of dark-brown “W-shaped” transverse markings from occiput to sacrum, bordered by a cream-colored stripe extending from behind the eyes to the insertion of the legs. This is true even for very old formalin-fixed and ethanol preserved specimens. However, both specimens ANSP 32189 from Pavalange and AMNH 47783, 51960-61 from Dande (all mature males) completely lack the transverse markings and present a much lighter coloration. The dorsolateral stripe is also much less evident than those of typical H. nzingae . Another marked difference between these specimens and those of typical H. nzingae is the much less acuminate enlarged dorsal tubercles, which in H. nzingae give the animal a very “spiny” appearance, contrary to the much smoother appearance of the above cited specimens ( Fig. 2 ). Finally, the habitus of these specimens is somewhat less depressed than that of H. nzingae .

Holotype. ANSP 32189 ( Fig. 1 ; Table 2 ), adult male, Pavalange, Luando Natural Reserve (-10.969765°, 17.612431°, 1127 m), Bié Province, collected by Harold T. Green in October 1930.

Additional specimens. AMNH 47783 , 51960 ( Fig. 1–3 ) two adult males and AMNH 51961 , adult female, from Dande (-11.166667°, 17.166667°, 1126 m), Malanje Province, collected by Herbert Lang and W. Rudyerd Boulton 4 August 1925 .

Diagnosis. A medium sized Hemidactylus , maximum snout-vent length 47.4 mm, and a short, blunt snout ( Fig. 1 ). Dorsal pholidosis heterogeneous, with 18 irregularly arranged longitudinal rows of subquadrangular, striated, feebly keeled tubercles at midbody. Two well developed pairs of postmentals, the inner pair longer than the outer pair, but about half the size of the mental, and in contact behind the mental. Ventrolateral folds distinct, about 26 scale rows across venter. Five divided scansors beneath first digit of both manus and pes, seven to eight beneath fourth digit of manus, nine beneath the fourth digit of pes. Males with a continuous series of 6–8 precloacal pores. Body dorsum brown with scattered dark markings (not forming transverse series), bordered by a thin faint creamcolored stripe extending from behind the eyes to the insertion of the legs.

Description of Holotype. The holotype is an adult male in good condition, but with partially detached, regenerated tail ( Fig. 1 ). The body shape is somewhat dorsoventrally flattened. Measurements and meristic characters of the holotype are presented in Table 2 . Head medium (HL/SVL 0.30), wide (HW/HL 0.59), bulky (HH/HL 0.43), distinct from neck. Canthus rostralis moderately distinct. Snout short (SE/HL 0.37); longer than eye diameter; scales on snout, canthus rostralis, forehead and between eyes heterogeneous, juxtaposed, and weakly pointed; scales on snout, canthus rostralis and forehead twice the size of those on the occipital and interorbital regions, canthus rostralis with slightly enlarged patch of scales. Eye small (ED/HL 0.23) supraciliaries large, pointed, those at the anterior end of orbit slightly larger. Ear opening oval (greatest diameter 1.0 mm); eye to ear distance greater than diameter of eye. Rostral wider than deep; three internasals, the two outer ones enlarged, and separated from each other by the smaller one in the middle; one supranasal on each side which is smaller than internasal, one pair of still smaller postnasals; rostral in contact with nostril, supralabial I, supranasal and internasal; nostrils small (> 1 mm), circular, each surrounded by supranasal, rostral, supralabial I and postnasal; 1–2 rows of scales separate orbit from supralabials. Mental triangular; two postmentals, smaller than the mental and in extensive contact with each other behind mental; outer pair about on third the size of the inner pair, separated from each other by inner pair and four gular scales. Inner postmental bordered by mental, infralabial I, outer postmental and two gular scales; outer postmental bordered by infralabial I and II, inner postmental, four to five small gular scales of which the outer one is enlarged and continue as a single row of enlarged scales below infralabials. Infralabials bordered by a double row of enlarged scales, about 2–8 rows of scales below infralabials II to VI are enlarged and weakly imbricate. Supralabials (to angle of jaw) 10 (right)/10 (left); infralabials (to angle of jaw) 9 (right)/8 (left). Body relatively stout, moderately elongate (TRL/SVL 0.35), ventrolateral folds without denticulate scales. Dorsal pholidosis heterogeneous, comprising conical, granular, striated scales intermixed with enlarged, fairly regularly arranged, longitudinal rows of 18 subquadrangulal, smoothly keeled, striated tubercles at midbody, extending from occipital region to tail, each enlarged tubercle roughly six to seven times longer than adjacent granules, surrounded by rosette of 11–14 small granules, two or three granules between two adjacent enlarged tubercles; enlarged tubercles on nape, shoulder small and pointed, those on occipital region heterogeneous. Ventral scales larger than dorsal, smooth, imbricate; midbody scale rows across belly 26; gular region with still smaller, subimbricate scales, those on lateral aspect of neck granular, anterior gular scales slightly larger than the rest. Eight precloacal pores in a continuous, mostly straight, series. Scales on the palm and sole smooth, imbricate, rounded; scales on dorsal aspect of upper arm larger than granules on dorsum, subimbricate and striated, dorsal aspect of forearm with smaller, striated, conical and granular scales, intermixed with a few enlarged conical tubercles; those on dorsal part of thigh and shank conical, granular, striated, intermixed with enlarged, striated, sub trihedral tubercles, which are numerous on shank compared to anterior aspect of thigh, posterior aspect of thigh lacks enlarged tubercles.

Fore- and hindlimbs relatively short, stout; forearm short (FL/SVL 0.15); tibia short (CL/SVL 0.16); digits moderately short, strongly clawed; all digits of manus and digits I–IV of pes indistinctly webbed; terminal phalanx of all digits curved, arising angularly from distal portion of expanded lamellar pad, half or more than half the length of the associated toepad; scansors beneath each toe in straight transverse series, divided except for distal and two to two basal scansors on digit I and one or two in all digits that are single; scansors from proximalmost at least twice diameter of palmar scales to distalmost single scansor: 5-7-8-7-7 (right manus), 7-8-9-9-8 (right pes). Relative length of digits: III = IV> II> V> I (right manus); IV> III = V> II> I (right pes). Regenerated tail.

Coloration (in preservative). Ground color of head, dorsum and limbs homogeneous light brown. Dorsum with one longitudinal middorsal light stripe and eight or nine rows of incomplete transverse dark bands. Tail very light brown. Venter immaculate white; palms and soles white.

Variation. Variation in scalation and body measurements of the specimens of H. hannahsabinae sp. nov. is reported in Table 2 . The additional specimens do not differ in any important details from the holotype.

Comparison with West and Central African congeners. Hemidactylus hannahsabinae sp. nov. is readily distinguished from H. kamdemtohami Bauer & Pauwels, 2002 , and H. richardsonii ( Gray, 1845) by the lack of basal digital webbing and from H. matschiei ( Tornier, 1902) by having spiny tubercles on the dorsum and small subcaudal scales. It may be distinguished from H. steindachneri by lacking a longitudinal row of keeled tubercles on the ventrolateral border of flanks, from H. hecqui by not having the nostril in contact with the first supralabial. Hemidactylus hannahsabinae sp. nov. can be distinguished from H. muriceus sensu stricto by a higher number of tubercle rows on the dorsum (16–18 versus 7–12), fewer granular scales between the dorsal tubercles (1–3 versus 5–10); and fewer nasals surrounding the nostril (2 versus 3). The new species can be distinguished from H. pseudomuriceus by having fewer precloacal-femoral pores in males (6–9 versus 14–17), a higher number of tubercle rows on the dorsum (16–18 versus 6–14), fewer granular scales between the dorsal tubercles (1–3 versus 5–10); and fewer nasals surrounding the nostril (2 versus 3). The newly described species can be distinguished from H. echinus by having a higher number of tubercle rows on the dorsum (16–18 versus 13–15), and by being smaller (max SVL 47.4 mm versus 68.0 mm). Hemidactylus hannahsabinae sp. nov. differs from H. ansorgii by a higher number of tubercle rows on the dorsum (16–18 versus 6–12), a lower number of precloacal-femoral pores (6–9 versus 10–11), fewer nasals surrounding the nostril (2 versus 3), a stockier body ( H. ansorgii has a slender body and narrow head with a short interorbital distance). Hemidactylus ansorgii also has a row of pointed tubercles separating the venter and the flanks, which are completely devoid of any tubercles, (see figure in Tornier 1902 and Perret 1975), whereas in H. hannahsabinae sp. nov. this ventrolateral row of tubercles is lacking, and tubercles extend across the flanks and dorsum.

Comparing the new species with the other Angolan congeners, Hemidactylus hannahsabinae sp. nov. is easily distinguishable from H. mabouia by its smaller size (maximum SVL 47.4 mm versus 67.4 mm), lower number of precloacal-femoral pores in males (6–9 versus 28–39), fewer granular scales between the dorsal tubercles (1–3 versus 5–10), and lower number of rows of ventral scales (26 versus 34–37). The new species may be distinguished from H. benguellensis by a much lower number of precloacal-femoral pores in males (6–9 versus 23–33), and fewer granular scales between the dorsal tubercles (1–3 versus 4–9). The new species can be distinguished from H. bayonii by its larger size (maximum SVL 47.4 mm versus 36.2 mm), by having higher number of tubercle rows on the dorsum (16–18 versus 14–16), fewer granular scales between the dorsal tubercles (1–3 versus 4–7), and fewer rows of ventral scales (26 versus 28–33). Hemidactylus hannahsabinae sp. nov. can be distinguished from H. longicephalus by having fewer granular scales between the dorsal tubercles (1–3 versus 3–6), and fewer rows of ventral scales (26 versus 30–33). It can be distinguished from H. paivae by its smaller size (max SVL 47.4 mm versus 68.4 mm), having a higher number of tubercle rows on the dorsum (16–18 versus 14–16), a lower number of granular scales between the dorsal tubercles (1–3 versus 4–9), and a lower number of rows of ventral scales (26 versus 28–34).

Hemidactylus hannahsabinae sp. nov. can be distinguished from H. nzingae , with which it was previously confused by Ceríaco et al. (2020), by subquadrangulal, smoothly keeled, striated tubercles at midbody (versus subtrihedral, strongly keeled tubercles at midbody in H. nzingae ), by having the enlarged tubercles of the same size and with similar keel across the dorsum (versus enlarged tubercles more strongly keeled and slightly larger on flanks and close to the tail than on the dorsum in H. nzingae ) ( Fig. 2 ); by having barely distinct dorsolateral bands, one longitudinal middorsal light stripe evident, eight to nine rows of incomplete transverse dark bands, on a homogeneous light brown background (versus the two well-marked longitudinal cream dorsolateral stripes and the prominent dark W-shaped markings and brown dorsal coloration in H. nzingae ( Fig. 3 )).

Distribution. The species in known from the central Angolan plateau in Malanje and Bié provinces ( Fig. 4 ).

Habitat and Natural History notes. Almost nothing is known about the natural history of the species. The holotype has an unidentified insect in the mouth. The habitat where the species occurs is dominated by Angolan Miombo woodlands ( Grandvaux-Barbosa 1970). The species is sympatric with H. nzingae in Dande , Malanje Province .

Etymology. The specific epithet hannahsabinae honors Hannah Sabin of the Sabin family, philanthropic supporters of herpetofaunal conservation.

Figures

FIGURE 1. Holotype of Hemidactylus hannahsabinae sp. nov. (ANSP 32189). Photos Luis M. P. Ceríaco.

FIGURE 2. Comparison between the dorsal scalation of H. nzingae (paratype, AMNH 47782) and H. hannahsabinae sp. nov. (paratype, AMNH 51960) from Dande. Photos Luis M. P. Ceríaco.

FIGURE 3. Comparison between H. nzingae (paratype, AMNH 47782) and H. hannahsabinae sp. nov. (paratype, AMNH 51960) from Dande, both specimens collected in 1925. Scale 10 mm. Photos Luis M. P. Ceríaco.

FIGURE 4. Distribution map for Hemidactylus hannahsabinae sp. nov. in Angola (red triangles) and Hemidactylus nzingae (blue dots).