Blaesodactylus ganzhorni, Vences & Miralles & Ineich & Rakotoarison & Glasenapp & Scherz & Köhler & Glaw & Raselimanana, 2025

Blaesodactylus ganzhorni sp. nov.

Figs. 1 View FIGURE 1 , 6–9 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 .

Holotype. ZSM 106/2006 (field number FGZC 885), adult male with everted hemipenes, collected by F. Glaw, J. Köhler, P. Bora and H. Enting on 26 March 2006 in Bendrao Forest ("Camp 3", geographical coordinates 18.7844° S, 44.8603° E, 427 m a.s.l.), Tsingy de Bemaraha National Park , Madagascar. GoogleMaps

Paratypes. A total of ten specimens, all from western Madagascar. ZSM 825/2010 (ZCMV 12766), collected by A. Miralles and A. Rakotoarison on 4 December 2010 in the Kirindy reserve CNCEREF (base camp; 20.0674° S, 44.6569° E, 55 m a.s.l.); GoogleMaps ZSM 232/2018 ( FGZC 5729 ), adult male with everted hemipenes, collected by F. Glaw, D. Prötzel, N.A. Raharinoro, R.N. Ravelojaona, A. Razafimanantsoa, J. Forster, K. Glaw, T. Glaw & C. Zanotelli on 31 March 2018 in Katsepy, garden of hotel " Madame Chabaud " (15.7624° S, 46.2436° E, 9 m a.s.l.) GoogleMaps ; ZSM 62/2023 (ZCMV 15810), collected at Tsingy de Namoroka, by A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo & A. Razafimanantsoa on 7 October 2023 at Tsingy de Namoroka (Campsite 1, east of Tsingy massif, near a small temporary lake, 16.4310° S 45.3661° E, 120 m a.a.l.) GoogleMaps ; ZSM 86/2023 (ZCMV 15835), collected by A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo & A. Razafimanantsoa between 17:00 and 19:00 on 8 October 2023 at Namoroka ( Petit Tsingy, east of Tsingy massif , 16.4354° S, 45.3684° E, 124 m a.s.l.) GoogleMaps ; UADBA-ZCMV 15888 , collected by A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo & A. Razafimanantsoa between 19:00 and 22:00 on 11 October 2023 at Namoroka ( Vicinity of Camp 2: Grand Tsingy, south of the Tsingy massif , 16.4697° S, 45.3467° E, 135 m a.sl.) GoogleMaps ; MNHN-RA 2013.1033 (I1764), collected by I. Ineich on 3 September 2012 at the Tsingy de Namoroka (16.4706° S, 45.4087° E, 139 m a.s.l.) GoogleMaps ; MNHN-RA 2013.1034 (I1793 b), collected by I. Ineich on 3 September 2012 at the Tsingy de Namoroka (16.4657 °S, 45.3531° E, 124 m a.s.l.) GoogleMaps ; MNHN-RA 2013.1035 (I1793 w), collected by I. Ineich on 8 September 2012 at the Tsingy de Namoroka (ca. 16.470° S, 45.336° E, ca. 125 m a.s.l.) GoogleMaps ; MNHN-RA 2013.1036 (I1796), collected by I. Ineich on 3 September 2012 at the Tsingy de Namoroka (ca. 16.45° S, 45.35° E, ca. 145 m a.s.l.) GoogleMaps ; MNHN-RA 2013.1037 (I1835), collected by I. Ineich on 10 September 2012 at the Tsingy de Namoroka (16.4675° S, 45.3594° E, 129 m a.s.l.) GoogleMaps .

Additional material. Four additional voucher specimens are assigned to the new species but not included in the paratype series due to the lack of molecular identification: MNHN-RA 2016.0053 (I1261), collected by I. Ineich on 23 October 2016 at the Tsingy de Namoroka   GoogleMaps (16.40° S, 45.30° E, ca. 122 m a.s.l.); MNHN-RA 2016.0051 and MNHN-RA 2016.0052 (respectively I1406 and I1420), collected by I. Ineich on 29 October 2016 at the Tsingy de Namoroka   GoogleMaps (no GPS readings available); UABDA-ZCMV 12712 collected by A. Miralles & A. Rakotoarison on 29 November 2010 in the Kirindy reserve   GoogleMaps CNCEREF (no exact locality); ZSM 826/2010 (ZCMV 12750), collected by A. Miralles & A. Rakotoarison on 3 December 2010 in the Kirindy reserve CNCEREF (Sentier des Pandanus; 20.0763° S, 44.6748° E, 57 m a.s.l.).

Diagnosis. Assigned to the genus Blaesodactylus based on large body size (SVL up to 113 mm; MNHN-RA 2013.1035), undivided lamellae under fingers and toes, dorsal skin made up of small granular scales with intermittent, regularly spaced enlarged conical tubercles, and molecular phylogenetic relationships. Within the genus, B. ganzhorni sp. nov. is distinguished from B. ambonihazo by mostly having a grayish dorsal coloration in life, with poorly contrasted dark gray markings (vs. more contrasted, often brownish dorsal color, with dark brown color especially on tail crossbands); from B. antongilensis by grayish dorsal coloration with poorly contrasted dark gray markings (vs. more contrasted, often brownish dorsal color, with dark brown color especially on tail crossbands); from B. boivini by smaller body size (maximum recorded SVL 113 mm vs. 144 mm), less strongly expressed tubercles especially on the sides of the head and above the ear (vs. usually distinct tubercles present on side of the head and above ear), weakly expressed whorls of tubercles over full length of original tail (vs. pairs of tubercles on proximal third of tail) and a nostril usually not colored black inside (vs. nostrils black); from B. microtuberculatus by presence of prominent and at least partially and weakly keeled enlarged dorsal tubercles (vs. flattened, unkeeled and very inconspicuous), presence of caudal tubercles (vs. absence), uniformly pale gular region (vs. mottled), and a nostril not colored black (vs. nostrils black); and from B. victori by presence of prominent and at least partially and weakly keeled enlarged dorsal tubercles (vs. flattened and unkeeled), presence of caudal tubercles (vs. absence), absence of dorsal whitish circular spots (vs. presence), and a nostril not colored black (vs. nostrils black). [note that in rare cases the color of nostrils refers to the inner skin/mucosa surrounding the nostril opening and differences may not be obvious in preserved specimens, perhaps depending on the state of fixation].

The new species is most similar to its sister species, B. sakalava , but differs from it morphologically by a relatively longer head (HW/SED 0.65–0.84 vs. 0.87–0.95; Table 2 View TABLE 2 ), relatively longer postmentals scales relative to width of mental scale (ratio mental width vs. postmental length 0.61–0.67 vs. 0.78–0.90), less expressed tubercles on the dorsum and especially laterally on head, with no or only small tubercles visible above the ear in most specimens (vs. more distinct tubercles, usually several distinct tubercles visible above ear, see Fig.6 View FIGURE 6 ), and probably larger longitudinal counts of dorsal and ventral scales, despite overlap in these values (LCDS 428–452 vs. 394–430; LCVS 185–213 vs. 173–189; Table 2 View TABLE 2 ).

Description of the holotype. ZSM 106/2006 (field number FGZC 885), adult male with fully everted hemipenes ( Fig. 9 View FIGURE 9 ) and original tail. Snout–vent length 103 mm, original tail length 138 mm, head relatively long (HeadL = 31.5 mm) and wide (HeadW = 21.8 mm), wider than neck; snout elongate (SnEye = 12.3 mm), longer than horizontal eye diameter (OrbD = 5.8 mm), internarial distance 3.9 mm; smallest interorbital distance 10.8 mm, distance from snout tip to ear 25.9 mm. Scales on snout and forehead small, granular, heterogeneous, larger than those on occipital region except for scattered conical tubercles (with 2–3 times size of adjacent scales); pupil vertical with crenelated margins; superciliaries forming a short fold with small spines at anterior and posterior margins. Ear opening obliquely, slit-like (EarL = 2.4 mm) on left side (hidden in a fold on right side); eye to ear distance (EyeEar = 9.4 mm) longer than diameter of eye; rostral rectangular, much wider (4.3 mm) than high (2.2 mm), with a median groove; one internasal scale; head scales on snout just posterior to the large scales small, forming an atypical fold that was already visible in life ( Fig. 8 View FIGURE 8 ) and runs from the eye along supralabials and nostrils. Rostral in contact with the first supralabials, supranasals, and one enlarged internasal; nostrils round, each surrounded by enlarged supranasal, rostral, first supralabial and three postnasals; mental pentagonal, wider (3.4 mm) than long (1.8 mm); median pair of postmentals elongated (3.8 mm long), each bordered anteromedially by mental, laterally in broad contact with other postmental along most of their entire length, bordered anterolaterally by first infralabial, laterally by second postmental, posteriorly by several very small chin granules; 12 (right) and 12 (left) supralabials on both sides, 11 infralabials on both sides. Body stout, with distinct ventrolateral folds. Dorsal scales on body smooth, granular to slightly conical and juxtaposed, with intermittent, regularly spaced, weakly keeled, enlarged conical tubercles (ca. 3 x size of granular scales) which form indistinct rows and are separated from each other by ca. 4–7 small granules; approximately 15 irregular rows of these enlarged tubercles across dorsum, counted at midbody from one side to the other. Number of dorsal tubercles in a longitudinal row from head to base of tail 59; number of dorsal scales along the body, from first scale after the internasals to the first scale row or whorl of the tail 452. Ventral scales much larger than dorsal scales, smooth, mostly hexagonal, juxtaposed. 42 scale rows across venter between ventrolateral folds; longitudinal count of the number of ventral scales from the mental scale to the cloaca 213; gular region with relatively homogeneous, smooth, rounded to oval scales, juxtaposed. No precloacal or femoral pores. Ventral scales of limbs similar to other ventral scales, dorsal surface of limbs without enlarged scales or tubercles. Hindlimbs short (39.0 mm) and robust. Digits on hands broadly dilated, distal portion of digits II–V free of pad, bearing a prominent recurved and uncolored 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 (10–13–16–18–14 manus; 11–13–15–17–14 pes); most lamellae undivided; interdigital webbing weakly developed. Relative length of digits (manus): IV>III>V>II>I; (pes): IV>III>V>II>I. Original tail slender, dorsoventrally depressed, tapering to tip, distinctly longer than SVL. Tail base with 3 smooth cloacal spurs on each side, the most dorsal being the largest. Scales on dorsal surfaces of tail largely homogeneous, but with weakly developed whorls of distinctly enlarged, keeled tubercles, which are most distinct in the four anterior whorls. Midventral subcaudal scales transversely enlarged more than half of tail width. Hemipenes fully everted (length 11.5 mm), apex bilobed, surface of apical lobes slightly granular, lacking distinctive calyces.

In life, ground color of dorsal surfaces of head, body, limbs and anterior part of the tail grey-brown with fine darker mottling and interspersed whitish tubercles ( Fig. 8 View FIGURE 8 ). Dorsum with a series of five moderately distinct and poorly delimited light gray crossbars between insertion of forelimbs and hindlimbs, darker anteriorly and fading towards the flanks. Tail with nine light gray crossbands, alternating with 10 dark gray bands. The bands are poorly delimited anteriorly, but show increasingly sharper borders towards the tail tip. Iris almost uniformly copper in distant view, with one reddish vessel like vertical line posteriorly and numerous dense fine red reticulations. Tongue tip red. Ground color of ventral surfaces of throat, chest, venter, ventral surfaces of fore- and hindimbs and tail base cream yellowish. Fine brown mottling on the anterior part of the throat, on ventral surfaces of limbs and the tail and distinct brown marbling on each side of the venter. Hands and feet including the adhesive lamellae light graybrown. In preservative, after 18 years in ethanol, the coloration is similar to that in life, but substantially faded. Light crossbands on the back have almost disappeared. Whitish tubercles are still distinct, especially on the posterior part of the back. Alternating crossbands on the tail are still distinct. Ventral ground color has faded to cream white, and the brown mottling on the throat and the marbling on each side of the venter have almost disappeared. Hemipenes are creamy white. Iris is gray.

Variation: The paratypes are generally similar to the holotype in meristic variables and proportions (see Table 2 View TABLE 2 for additional details). The subadult paratype ZSM 86/2023 from Namoroka has a more contrasting coloration with very distinct crossbands on body and tail, but with a long uniformly light-colored tail tip (which is possibly regenerated). The juvenile paratype ZSM 826/2010 from Kirindy (not sequenced) has a brownish ground colouration in preservative with distinct crossbands on dorsum and tail. Another juvenile from Kirindy (ZCMV 12750), had a mallow-grayish overall dorsal coloration, marked with darker transverse bands and studded with many pale yellow small dots; a striking yellow coloration of the ventral side, particularly bright on the labial area; and a tail alternating dark gray and white rings, and whose color contrast is accentuated posteriorly ( Fig. 8 View FIGURE 8 ). ZSM 62/2023 (ZCMV 15810) from Namoroka bears an unusual wide, strikingly dark, almost black, patch on the dorsum. The fold of skin on the rostrum is apparently unique to the holotype, and almost certainly represents a malformation or an injury that may have originated during capture of the animal.

Etymology. The species name is an eponym, i.e., a noun in genitive case, dedicated to Jörg Ganzhorn, Hamburg University, in recognition of his enormous contributions to the research and conservation of Madagascar's biodiversity.

Natural history. A primarily nocturnal, but partially diurnal species.At Namoroka one specimen on 3 September 2012 was observed feeding during the day (sunny, without rain) with a prey in its mouth around 13:00 h, on a tree trunk about 1 m above the ground (MNHN-RA 2013.1033; a gravid female, with two eggs in abdominal cavity). The species can be found on tree trunks at 0.5–3 m above the ground, often in degraded dry deciduous forest ( Fig. 10 View FIGURE 10 ), often (as with other dry forest Blaesodactylus ) in areas of baobab trees. During the day animals take refuge either in holes in tree trunks or in cavities on cave walls or stay on the trunk in shadow between two trunks, sometimes hiding under loose bark. Very often, they keep their heads or the entire body outside of their refuge during the day and escape rapidly into the hole when feeling threatened or disturbed. In Kirindy, specimens have been found by night, at eye-level, on the trunks of medium-sized trees and on the wall of wooden cabins at the CNFEREF ecolodge. In Namoroka an individual was found at 0.5 m above the limestone, upside down at 20:45 h, suggesting that this species may hunt also on "tsingy" limestone rocks. Another specimen (ZCMV 15810) was spotted perched on a tree about 1 meter high in the small patch of forest surrounding the team’s campsite (Camp 1). ZCMV 15835 was found nestled among the cliffs of the "Petit Tsingy" site at approximately 2 m high. ZCMV 15888 was observed perched in a tree near the grand Tsingy, also at a height of ca. 1 m. It also can be found near the ground on dead tree trunks. Several females were gravid when observed at Namoroka in September 2012 but not in October 2016.

Distribution. Known from arid western Madagascar, occurring approximatively between the two large rivers, Mangoky in the south and Betsiboka in the north ( Fig. 3 View FIGURE 3 ).