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| Zig zag Miralles, Schmidt, Belluardo, Rahagalala, Monvoisin, Ratsoavina, Köhler, Glaw & Vences, 2026 |
Abstract
The present work reports on the discovery of a new sand swimming lizard (Scincidae: Scincinae) in Madagascar. This limbless and eyeless skink was found during fieldwork in the northern part of the “great white sand belt”, a series of patchy white sand areas encircling the island’s western sedimentary basins. The new taxon shows a distinctive combination of derived morphological traits (miniaturized, limbless, elongated body, with absent or scale-covered eyes and ear openings, and a reduced head scale pattern) reminiscent of other Malagasy fossorial skinks adapted to sandy habitats (e.g. Voeltzkowia, Grandidierina and some Paracontias). Phylogenetic analyses based on two datasets (multilocus DNA from Sanger sequencing and genome-wide DNA sequences derived from double-digest Restriction Associated DNA [ddRAD]) reveal a highly divergent phylogenetic position of this taxon and, given its distinct morphology, justify its description as a new species in a new genus, Zig zag gen. nov. & sp. nov. This marks the first genuine field discovery of a new genus of Scincidae in Madagascar since the 19th century, i.e., the discovery of a formerly unknown deep clade rather than an identification (and split) from an already recognized genus. Our results also shed light on the ancient evolutionary history of this taxon and its sister clade, Paracontias. Finally, the present work explores the factors that may explain why ecosystems characterized by white sand substrates, an ecosystem often neglected in biodiversity research, but present in various regions of the globe (e.g., Florida sand scrub, South American WS savannah, Indonesian Keranga) have seemingly so frequently promoted the convergent evolution of fossorial squamates.
Taxonomy, new genus, new species, Phylogenomics, psammophily, fossoriality
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| Overview of the White Sand Belt: Map of Madagascar showing WS patches identified by Miralles et al. (2025) (white dots), with the distribution of sand-specialist, legless and fossorial skink genera (data from the present study; Glaw & Vences 2007; Köhler et al. 2010; Miralles et al. 2011b, 2015, 2016a, 2025). |
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| Coloration in life of Zig zag gen. nov. et sp. nov.: Holotype MNHN-RA-2025.0001 and paratype ZSM 104/2023 in dorsolateral and lateral views, both from Baie de Baly; and paratypes ZSM 105/2023, ZSM 107/2023 (close-up of the dorsal, lateral and ventral view of the head), ZSM 108/2023 and ZSM 112/2023 (juvenile), all four from Benetsy. Not to scale. |
Zig gen. nov.
Type species. Zig zag sp. nov. See the species description below.
Etymology. The name Zig is an arbitrary combination of letters in the sense of the International Code of Zoological Nomenclature Articles 30.1.4.1 and 30.2.2, and we assign it the feminine gender. We have searched all available taxonomic databases and could not find any evidence that this name has ever been used to refer to a genus of animals, and we therefore conclude that it is available.
Diagnosis of the genus Zig. Based on molecular phylogenetic relationships, a genus in the family Scincidae, subfamily Scincinae, sister to Paracontias. The genus Zig is distinguished from all other known Malagasy scincines by the following combination of characters: (1) the complete absence of limbs (versus four well developed and pentadactyl limbs in Madascincus, Amphiglossus, Flexiseps, Brachyseps, and relictual fore- and hindlimbs in some—but not all—species of Grandidierina, Pygomeles, Pseudoacontias, Voeltzkowia), (2) a “blind” morphotype (versus presence of an eye-opening, in Amphiglossus, Flexiseps, Brachyseps, Madascincus, Pygomeles, Pseudoacontias, and all Paracontias species except P. minimus), (3) the presence of a single supraocular (versus two to four supraoculars, most often four, in ... ... with the last supralabial and the nuchal (versus presence of two secondary temporals in all the other genera), and (7) the position of the subocular scale corresponding to the second supralabial (versus the third, the fourth, or occasionally the fifth in all the other genera).
Distribution. Madagascar, Mahajanga basin, western bank of the Betsiboka River.
Zig zag sp. nov.
Etymology. The specific epithet ‘zag’, an arbitrary combination of letters, is used here to form a pun on ‘zig zag’, in reference to the very characteristic sinusoidal tracks left by this species when moving in the white sand. It is treated as an invariable noun in apposition to the genus name.
Diagnosis. As Zig represents a monotypic genus, the generic diagnosis of Zig above is also suitable to distinguish the species Zig zag from any other Malagasy scincine species. Additionally, Zig zag differs from the other superficially similar worm-like Malagasy species (i.e. limbless, “blind”, elongated and miniaturized morphotype such as Grandidierina spp., Voeltzkowia spp. and Paracontias minimus) by the following combination ...
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| White sand substrate in Zig zag gen. nov. et sp. nov. habitats: In situ view of sand soil surface, with sigmoidal tracks let by Zig zag in Baie de Baly (A), and detailed views (B, C) of the almost pure quartz sand present in Benetsy (identical in Baly, see Miralles et al. 2025). (D) Diagram illustrating the physical properties of white sands when exposed to heavy rainfall or, conversely, to intense solar radiation. Photographs B and C by André Freiwald. |
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| Habitat of Zig zag gen. nov. et sp. nov. (A) White-sand savannah with Bismarckia palm trees near the village de Baly. (B) Shrubby white-sand savannah near the village of Benetsy. (C) Soil stratification in Zig zag microhabitat at Benetsy: (1) vegetation patches providing shade, (2) layer of dry vegetal litter, (3) dense mat of fine roots, (4) deeper layer made of almost pure white sand. |
Aurélien MIRALLES, Robin SCHMIDT, Francesco BELLUARDO, Ny Ando RAHAGALALA, Evariste MONVOISIN, Fanomezana M. RATSOAVINA, Jörn KÖHLER, Frank GLAW and Miguel VENCES. 2026. Zigzags in the White Sand Belt: A New, highly divergent lineage of Sand-swimmer Skink from Madagascar (Squamata: Scincidae). Megataxa. 19(1); 176-212. DOI: doi.org/10.11646/megataxa.19.1.3 [2026-02-23]
