Madascincus minotaurus Miralles, Scherz, Roberts, Rakotoarison, Glaw & Vences, 2026, sp. nov.

Abstract

Madascincus minotaurus sp. nov. Figures 3, 4, 5, 6, 7, 8, 9 Holotype. MADAGASCAR – Boeny Region • 1 adult ♀; Tsingy de Namoroka National Park, Petit Tsingy; 16°26’7”S, 45°22’6”E; 125 m a. s. l.; 08 Oct. 2023, 07: 00–09: 00 a. m.; A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo and A. Razafimanantsoa leg.; ZSM 116 / 2023 (ZCMV 15819). Other material examined. MADAGASCAR – Boeny Region • 1 tissue sample (MIRZC 1217, voucher not collected); Tsingy de Namoroka National Park, Grand Tsingy, south of the Tsingy massif, Camp 2; 16°28’9”S, 45°20’54”E, 128 m a. s. l.; 10 Oct. 2023, 03: 00–07: 00 p. m.; A. Miralles, N. A. Rahagalala, A. Rakotoarison, D. Razafimanafo and A. Razafimanantsoa leg. • 1 specimen photographed (unsampled and uncollected); Tsingy de Namoroka National Park, Grand Tsingy; 16°28’1”S, 45°21’0”E; photographed by Ivan Ineich on 3 Sept. 2012. Furthermore, four specimens deposited in the UMMZ collection and registered as Madascincus intermedius (junior synonym of M. polleni) have been collected only 50 m from the sample MIRZC 1217. Given their collection locality and the superficial resemblance between M. polleni and M. minotaurus sp. nov., we hypothesize that these specimens likely correspond to the new species: UMMZ 222106 –222109, from Namoroka, camp 1, at the edge of Tsingy (16°28’11”S, 45°20’54”E); Dec. 1996; C. J. Raxworthy, J. B. Ramanamanjato, A. Razafimanantsoa and J. Rafanomezantsoa leg. These specimens / samples are not designated as paratypes because the specimens were not studied. Diagnosis. Madascincus minotaurus sp. nov. differs from all other species in the genus Madascincus by the combination of a lower number of scales around midbody and a higher number of ventrals. It differs from the species of the melanopleura group (its sister clade formed by M. melanopleura, M. ankodabensis and M. minutus) by a distinctly higher number of ventrals (68, versus 55 to 63) and paravertebral scales (69, versus 51 to 65), by a bell-shaped frontal scale (versus hourglass-shaped, i. e., frontal constricted by the first pair of supraoculars) and a distinct, lighter and warmer coloration (versus darker and brownish). Description of the holotype. (Figs 3, 4) An adult female, with a single large egg in the abdominal cavity. Good state of preservation, with exception of the left arm and the left leg that have been removed for molecular analyses. SVL (39.9 mm) 7 times head length (5.9 mm), almost as long as tail (41.0 mm, either entire or completely regenerated). Limbs very short, SVL 7.1 times forelimb length (5.5 mm) and 4.3 times hind limb length (8.9 mm). Snout short and rounded on lateral aspect, with a rostral tip bluntly rounded in dorsal aspect. Rostral wider than long, contacting first supralabial scales, nasals, and supranasal scales. Paired supranasal scales in median contact, contacting loreals and postnasal scales. Frontonasal scales roughly triangular, wider than long, contacting loreals, first supraciliaries and first supraoculars. Prefrontals absent. Frontal longer than wide, wider posteriorly, in contact with frontonasal, supraoculars, parietals and interparietal. Four supraoculars, all of them in contact with frontal; second pair larger than posteriormost pair; first pair not constricting frontal (frontal bell-shaped sensu Andreone and Greer 2002). Frontoparietals absent. Interparietal as long as wide, well separated from supraoculars; parietal eyespot present with parietal eye evident. Parietals contact posterior to interparietal. Two pairs of enlarged nuchals, each nuchal scale width corresponding to two transverse rows of adjacent cycloid scales. Nasals slightly larger than nostrils; contacting rostral, first supralabials, postnasals and supranasals. Postnasals present, separating supranasals from first supralabials, and nasals from loreals. Loreal single, slightly higher than long. Preocular trapezoidal, as long as high, single. Presubocular roughly square, single. Six supraciliaries on both sides, in continuous row; first and last pairs significantly larger than the intermediate ones; last pair projecting onto supraocular shelf. Pretemporals single, contacted by parietal. Two postsuboculars; upper contacting pretemporal; both contacting penultimate supralabial. Lower eyelid moveable, with a spectacled translucent window; lower palpebrals small, longer than high. Contact between upper palpebrals and supraciliaries seemingly direct but flexible, i. e., palpebral cleft narrow. Primary temporal single. Two secondary temporals; upper long, contacting pretemporal anteriorly and overlapping lower secondary temporal ventrally. Six supralabials, with the fourth being the enlarged subocular, contacting scales of the lower eyelid. External ear opening rounded, without lobules. Mental wider than long, posterior margin convex. Postmental wider than long, contacting first two pairs of infralabials. Six infralabials. Three pairs of large chin scales, both members of first pair in contact, both members of second pair separated by a single median scale, and members of third pair separated by three scale rows. No scales extending between infralabials and large chin scales. Gulars similar in size and outline to ventrals. All scales, except head shields and scales on palms, soles, and digits, cycloid, smooth, and imbricate; 20 longitudinal scale rows at midbody; 69 paravertebrals, similar in size to adjacent scales; 68 ventrals. Inner preanals overlapped by outer. Both anterior and posterior limbs pentadactyl; fingers and toes relatively short, clawed, except the fifth finger which does not bear a claw; relative length of toes in the following order: I <II <III <V <IV. Subdigital lamellae smooth, single, with 7 under right fourth finger, 15 under right fourth toe. Coloration of the holotype. In preservative, specimen with a pair of lateral dark brown stripes (about one scale wide on the neck), well defined anteriorly (overlapping rostral, mental, first four supralabials, loreals, and presuboculars), then progressively breaking up into a thin dashed lines posteriorly to forelimbs, hardly distinguishable from the rest of the dark dots covering the dorsum and the flanks. Presence on the anterior part of the body of a pair of short light cream dorsolateral stripes, separating the dark lateral stripe from the bronze dorsal field, well-visible from supranasals, supraciliaries, temporal area and the neck to the level of the insertion of the forelimbs, but progressively fading and disappearing posteriorly. Dorsum and dorsal sides of forelimbs, hindlimbs and tail light bronze. The bronze dorsal field and the slightly lighter flanks are covered by numerous little dark dots, with each cycloid presenting a distinctive lunular at their insertion point and a cloud of tiny dark pigmentations at their middle, resulting in many thin dash lines (14 at midbody). No distinct border between the background coloration of the darker dorsal and the lighter ventral sides. Immaculate light cream ventral field extending from lower side of head (mental excluded), throat, lower side of limbs and venter, to ventral side of tail. Palms and soles greyish, darker than venter. In life, the coloration pattern was relatively similar to that in preservative, but with a slightly brighter and warmer overall aspect, evoking more a copper than bronze background coloration. Light dorsolateral stripes on the head and the neck were more discernable and extending along the entire length of the body until hindlimbs insertion and presenting a brighter orange tint. Presence of slightly iridescent glints of scales (cf. Fig. 3 A, B). Variation. The only available additional information concerns a specimen photographed by Ivan Ineich at the Grand Tsingy; it presents a color pattern identical to that of the holotype (Fig. 3 C). Etymology. The specific epithet minotaurus, invariable noun in apposition, is derived from Min ṓtauros (ancient Greek: Μινώταυρος), a taurine creature of the Greek mythology. It alludes to the labyrinthine structure of the Tsingy de Namoroka, within which the new species, like the Minotaur in Daedalus’s construction, appears unable to escape. Distribution. (Figs 5, 6, 9) Only known from the Tsingy area of the Namoroka National Park, North West of Madagascar, and probably distributed all over this karstic massif and surrounding patches of deciduous forest. The holotype was collected at the border of the Petit Tsingy (eastern part of the Namoroka massif), at the limit between the rock corridor and the adjacent dry deciduous forested area. The sample MIRZC 1217 was found on the border of the Grand Tsingy (southern part of the massif). Ecology. The two specimens observed in 2023 were foraging in dense leaf-litter layers in shaded areas (by day) or active at dusk. Conservation status. Considering that Madascincus minotaurus sp. nov. is likely widely distributed across the Namoroka karst massif, and based on satellite imagery, it is possible to conclude that its EOO might at least range from 50 to 200 km ², depending on whether the species is present in peripheral karstic isolates too (cf. Fig. 6). The possibility of a broader distribution within the region for this species remains however plausible and cannot be dismissed in the absence of additional data. Although the Namoroka massif is well preserved and currently shows no significant signs of anthropogenic disturbance, the new species’ habitat is likely highly fragmented. Pending further information to confirm this species’ range, population status, and potential threats, we recommended assigning the species the status VU (Vulnerable) based on the criteria D 2 of the IUCN Standards and Petitions Committee (2024).