Blaesodactylus ambonihazo, Bauer, Aaron M., Glaw, Frank, Gehring, Philip-Sebastian & Vences, Miguel, 2011

Bauer, Aaron M., Glaw, Frank, Gehring, Philip-Sebastian & Vences, Miguel, 2011, New species of Blaesodactylus (Squamata: Gekkonidae) from Ankarafantsika National Park in north-western Madagascar, Zootaxa 2942, pp. 57-68 : 60-65

Blaesodactylus ambonihazo sp. nov.

( Figures 2–5 )

Holotype. ZSM 469/2001 (field number MV 2001-340), adult male ( Fig. 2 A); Ankarafantsika National Park (Ampijoroa), Mahajanga Province, northwestern Madagascar (16°18’S, 46°49’E, 173 m above sea level), collected by M. Vences, D. Vieites, G. García, V. Raherisoa, and A. Rasoamamonjinirina, on 26 February 2001.

Paratypes. ZSM 470/2001 (field number MV 2001-341), subadult/adult male, ZSM 471/2001 (field number MV 2001-345), adult female; both with same data as holotype; ZFMK 51141, collected by F. W. Henkel and J. Sameit in 1988-1989; ZFMK 52290, collected by F. W. Henkel and W. Schmidt without precise collecting date; ZFMK 55257, collected by F. W. Henkel, without precise collecting date, three adult specimens from Ankarafantsika, Mahajanga Province, northwestern Madagascar, probably all females.

Etymology. The species name is composed of the two Malagasy words hazo (tree) and ambony (on) and refers to the tree-dwelling habits of the new species (the terminal "y" of ambony is replaced by "i" as typical in Malagasy composite words). The species name is used as noun in apposition.

Diagnosis. A mid-sized (max. SVL at least 108 mm), robust-bodied Blaesodactylus with tail much longer than SVL ( Fig. 2 ). Snout elongate, gular granules small and regular, internarial region convex. 136–155 scale rows around midbody, 17–20 longitudinal rows of enlarged, keeled tubercles on dorsum. Fourth digit of pes with 15 undivided subdigital lamellae. 8–10 tubercles per row at base of tail, caudal tubercles limited to basal portion of tail. Body with 5–6 broad, more-or-less well-developed brown cross bands between nape and sacrum, original tail boldly banded, venter pale. Blaesodactylus ambonihazo sp. nov. may be differentiated from B. boivini by its smaller size (maximum SVL 108 mm versus 144 mm), homogeneous (versus heterogeneous) gular granules ( Fig. 4 ) and uniform pale venter (versus mottled with areas of dark pigmentation). It differs from B. sakalava in its uniform (versus usually heterogeneous) gular granules, longer snout ( Fig. 5A ) with internarial depression (versus convex internarial region), more restricted caudal tubercles (on proximal 40% only versus entire length of original tail, and some dorsal tubercles bearing fine radial keels as well as a central longitudinal keel ( Fig. 5 B; versus longitudinal keel only). It is distinguished from B. antongilensis , with which it has previously been confused by its uniform gular granules (versus enlarged anterior granules), lower number of dorsal tubercle rows (17–20 versus up to 24), and less strongly keeled and more widely spaced tubercles (2–3 intertubercular granules versus 1–2).

Description of the holotype. ZSM 469/2001, adult male. SVL 107.9 mm. Skin torn on top of head, above left shoulder, and on right flank; muscle removed from ventral surface of right hind leg for tissue sample. Head relatively long (HeadL/SVL = 0.26) and very wide (HeadW/HeadL = 0.80), not depressed (HeadD/HeadL = 0.46); distinct from neck. Loreal region strongly inflated, frontonasal region strongly concave, snout elongate (SnEye/HeadL 0.46), blunt, longer than eye diameter (OrbD/SnEye = 0.54); scales on snout and forehead small, granular, heterogeneous, with minute rugosities or pustulations; scales on snout larger than those on occipital region except for scattered conical tubercles (~ 4–5 times size of adjacent scales); 24 scales across narrowest point of frontals, 54 between superciliary scale rows. Eye large (OrbD/HeadL = 0.25); pupil vertical with crenelated margins; superciliaries forming a short brillar fold with small spines at anterior and posterior margins. Ear opening obliquely oval, small (EarL/HeadL = 0.13); eye to ear distance longer than diameter of eye (EyeEar/OrbD = 1.23). Rostral quadrangular, much wider (4.6 mm) than high (2.3 mm), with no median groove. Enlarged supranasals separated by two transverse series of internasal scales, 3 anteriorly, bordering rostral, and 2 posteriorly; rostral in contact with first supralabials, supranasals, and 3 internasals; nostrils round, each surrounded by supranasal, rostral, first supralabial and two postnasals, and a crescentic nasal, itself bordered posteriorly by 3 postnasal scales; 3–4 rows of small scales separate rim of orbit from supralabials. Mental rhomboidal, wider (3.7 mm) than deep (2.1 mm); median pair of postmentals elongated (3.1 mm long), each bordered anteromedially by mental, medially in broad contact with other postmental along entire length, bordered anterolaterally by first infralabial, laterally by second postmental, posteriorly by 3 enlarged chin scales (5 in total, median chinshield bordered by both median postmentals); 11 (right) to 12 (left) supralabials, 11 (right) to 12 (left) infralabials on both side. Right side of head posterior to torn skin with healed wound exhibiting early stages of scale differentiation.

Body stout, relatively short (TrunkL/SVL 0.43) with moderately developed ventrolateral folds. Dorsal scales smooth, granular to conical and recumbent, juxtaposed; 136 scale rows around midbody, intermixed with enlarged, smooth to longitudinally keeled to tubercles (~6 times size of adjacent scales, largest on flanks, and smallest in occipital region), some with fine radial striations, extending from occipital and postorbital regions to tail base, more conical and strongly keeled over sacrum and on tail base; tubercles in 17–20 rows at midbody. Ventral scales much larger than dorsals, smooth, imbricate, free margin rounded on chest, becoming more pointed posteriorly, largest on abdomen except for rows immediately anterior to vent; 34 scale rows across venter between ventrolateral folds; gular region with relatively homogeneous, smooth, rounded to oval scales, juxtaposed anteriorly to subimbricate posteriorly. No precloacal or femoral pores, no enlarged femoral scales. Preaxial scalation of limbs subimbricate, postaxial granular, dorsal surface of limbs without tubercles. Scales of palms and soles smooth, flattened, round, subimbricate.

Limbs short and robust (ForeaL/SVL 0.13; CrusL/SVL 0.19). Digits broadly dilated, distal portion of digits II– V free of pad, bearing a prominent recurved claw partly sheathed between a pair of scales, distal portion of digit I not free of pad, claw minute and lying in a groove in the adhesive pad; number of broad lamellae beneath each digit (9– 13 –14–14–12 manus; 12–13–14–15 –11 pes); all lamellae, except distalmost slightly bowed, undivided except for distalmost lamellae of digit I; interdigital webbing weakly developed. Relative length of digits (manus): IV> III> III> II>V> I; (pes): IV>III> V> II> I.

Mostly regenerated tail slender, tapering to tip; much longer than snout-vent length (TailL/SVL = 1.35), dorsoventrally depressed. Tail base with 3 smooth cloacal spurs on each side, largest anteriormost. Scales of tail dorsum heterogeneous — rectangular to pentagonal or hexagonal, subimbricate; midventral subcaudal scales transversely enlarged but less than half of tail width; tail segmented, each segment 8 dorsal scale rows and 3 transversely enlarged subcaudal scales in length; posterior edge of each segment with a row of enlarged keeled tubercles, 10 across basalmost segment, decreasing in number distally; lateral tubercles decreasing in size and becoming keelless on distsal portion of original tail. Regenerated portion of tail with some segmentation evident but scalation irregular and tubercles lacking.

Hemipenes partly everted, pedicel and truncus not well demarcated from one another, apex bilobed, surface of apical lobes granular, lacking distinctive calyces.

Coloration (in preservative). Body dorsum grayish brown with a series of weakly developed darker brown crossbars, one across occiput and nape, one across shoulders, two between axilla and groin, and one on anterior part of sacral region, another bar on tail base. A faint pale vertebral line bisecting anterior 3 crossbars. Flanks with some faint mottling. Limbs mottled. Tail with faint alternating brown and white bands, becoming bolder at approximately one third of tail length from cloaca, faint again on distal portion of tail. Head medium brown with beige labial scales, rictus, and posteroventral orbital margin. Venter cream, palms and soles grayish. Coloration in life ( Fig. 3 ) generally similar to that in preservative, but darker and more contrasting. The iris was amber in colour.

Variation. Variation in mensural and selected meristic features is summarized in Table 1 . The ZSM paratypes shared the same number of ventral scale rows and internasal scales as the holotype and the male paratype ZSM 470/2001 had the same number of cloacal spurs. Caudal tubercles on the original tail of ZSM 470/2001 are in a maximum of 8 per row and are present only on whorls of the basal approximately 40% of the tail. Dorsal coloration of male paratype ZSM 470/2001 is much bolder than in the holotype, with chocolate brown cross markings on a beige background, 3 crossbars between axilla and groin, and 12 brown bands on the postpygal portion of the tail, very bold from the fourth band distally ( Fig. 2 B). Crown of head with diffuse, irregularly distributed cross markings; internasal and anterior frontal region dark brown; a vague dark stripe on each loreal region to anterior midpoint of orbit, continuing behind eye and above ear to join with brown nape marking. Female paratype ZSM 471/ 2001 with faded pattern similar to holotype, nape marking faint, partly fused with shoulder crossbar ( Fig. 2 C). No enlarged cloacal spurs, endolymphatic sacs greatly enlarged and bulging along neck. Both paratypes exhibit some skin damage; on the left chest of the male and on the nape of the female, which also has a healed wound on the right flank. The hemipenes are everted in ZSM 470/2001.

No detailed mensural data were taken from the ZFMK paratypes, but all diagnostic characters were verified in these specimens. The three specimens are in good state of preservation. SVL is 94.4 mm for ZFMK 55257, 99.4 mm for ZFMK 52290, and 97.1 mm for ZFMK 51141. The three specimens have 17–18 dorsal tubercle rows and uniform gular granules. Their tails are either regenerated or damaged, but in one of the specimens it is recognizable that the caudal tubercles become indistinct after the proximal one-third of the tail. Fine radial keels on some dorsal tubercles are present and especially clear in ZFMK 52290, less distinct in the other two specimens possibly because of fixation differences.

Photographs of Blaesodactylus taken by A. Hartig at Ankarafantsika (not shown) confirm the characters described as diagnostic for the new species. Four of the five photographed individuals have original tails with tubercles visible on the proximal part of the tail only. All original tails are boldly banded either with black and white or with black and brown. The colouration of the back varies from indistinctly marbled with different tones of brown to a distinct pattern of largely symmetrical whitish blotches or even an almost rectangular network pattern.

Mori et al. (2006) provided a colour photograph of one specimen and morphological data for nine Blaesodactylus individuals from Ampijoroa, most likely belonging to B. ambonihazo . According to their data snout-vent length ranged from 66.6-108.3 mm (mean 84.7 mm), tail length (original and regenerated) from 40-150 mm (mean 99.5 mm), and body mass was 6.7-30.8 g (mean 13.9 g).

Distribution. So far, the species is reliably only known from Ankarafantsika National Park in north-western Madgascar, but we assume that it is more widespread and might occur in other remnants of dry forest in this largely deforested region (see Discussion below).

Natural history. Specimens were collected on large tree trunks around Lac Ravelobe, next to Ampijoroa forest station. No further details of the collection circumstances were noted. Mori et al. (2006) observed individuals of Blaesodactylus most likely belonging to B. ambonihazo in the Ampijoroa forest within the Ankarafantsika reserve, perching on trees in the "Jardin Botanique A" and on walls of the buildings in the Ampijoroa station. These authors found seven individuals on trees in the morning which were partially hidden in shelters or crevices in shade and seemed to be inactive. These observations suggest some diurnal activity in this generally nocturnal species.

Figures

FIGURE 2. Holotype and two paratypes of Blaesodactylus ambonihazo sp. nov. A. Male holotype ZSM 469 / 2001. B. Male paratype ZSM 470 / 2001. C. Female paratype ZSM 471 / 2001. Scale bars = 20 mm.

FIGURE 3. Holotype of Blaesodactylus ambonihazo sp. nov. in life, photographed at Ampijoroa, Ankarafantsika National Park.

FIGURE 4. Ventral views of gular region in Blaesodactylus spp. A. B. boivini (ZSM 313 / 2004). B. B. sakalava (ZSM 589 / 2000). C. B. antongilensis (ZSM 410 / 2005). D. B. ambonihazo sp. nov. (ZSM 469 / 2001). Note the fine uniform gular granules in Blaesodactylus ambonihazo sp. nov. and the more heterogeneous patterns in its congeners.

FIGURE 5. A. Dorsal view of heads of Blaesodactylus sakalava (ZSM 1017 / 2003, left) and B. ambonihazo sp. nov. (ZSM 469 / 2001, right) illustrating the longer, more pointed snout in the latter species. B. Dorsal scalation of B. ambonihazo sp. nov. illustrating the radial keeling on some tubercles (arrows) and the relatively wide spacing between tubercles.

Tables

TABLE 1. Mensural and meristic data for the holotype and two paratypes of Blaesodactylus ambonihazo sp. nov.

Sex	Holotype ZSM 469/2001 M	Paratype ZSM 470/2001 M	Paratype ZSM 471/2001 F
SVL	107.9	85.9	103.5
TailL	145.5 (regenerated)	103.2 (original)	12.2 (broken)
HeadL	27.6	23.0	27.3
HeadW	22.2	17.5	24.1
HeadD	12.6	11.2	13.1
SnEye	12.6	10.2	12.8
OrbD	6.8	6.1	6.6
EarL	3.5	3.1	3.4
EyeEar	8.4	6.8	8.4
Interorb	10.9	9.4	11.2
Internar	3.4	2.8	3.6
ForeaL	14.5	11.0	12.9
CrusL	20.7	15.2	22.1
TrunkL	45.9	34.9	42.5
Midbod	136	154	155
TubRow	17–20	17–19	17
VentSc	34	34	34
SupraL	12/11	11/11	12/12
InfraL	12/11	11/12	12/11
LamMan	9–13–14–14–12	9–12–14–14–12	10–12–13–14–11
LamPes	12–13–14–15–11	11–14–15–15–13	11–13–15–15–12