A new species of the genus Cyrtodactylus is described from Khanh Hoa Province, South-central Vietnam based on genetic divergence and morphological differences. Cyrtodactylus arnei sp. nov. is distinguished from the remaining Indochinese bent–toed geckos of the Cyrtodactylus irregularis group by having the unique combination of the following characteristics: size medium (SVL 70.9–78.0 mm); dorsal tubercles in 15–17 irregular rows; 34 or 35 ventral scale rows; 12–15 enlarged femoral scales on each side, in continuous series without gap between precloacal and femoral scales; precloacal pores absent in females, 5–7 in males, in a continuous row; femoral pores absent; postcloacal spurs 0–3 on each side; 19–21 lamellae under toe IV; dorsal pattern between limb insertions consisting of four narrow light bands with dark edges and a transversal row of dark spots in the middle; subcaudal scales enlarged, forming broad transverse plates. In phylogenetic analyses, the new species was nested within the Cyrtodactylus irregularis group without any clear sister taxon. Genetically, Cyrtodactylus arnei sp. nov. is divergent from other species within the Cyrtodactylus irregularis group by at least 10.97% (COI) and 14.39% (ND2) based on two fragments of the mitochondrial gene.

Key words: Cyrtodactylus arnei sp. nov., Cyrtodactylus irregularis group, morphology, phylogenetic relationships, taxonomy

Two new species of Cyrtodactylus from the khasiensis group are described using morphological characters supported by molecular analyses based on the mitochondrial ND2 gene. Cyrtodactylus makwanpurgadhiensis sp. nov. and C. chure sp. nov. from the Siwalik Mountains in central Nepal are at least 11.2% divergent from other Nepalese congeners and 16.7% from each other and can be distinguished by a combination of morphometric and meristic traits. The description of two new species from the Siwalik Mountains underscores the conservation significance of this region, a relatively young, dry, and geologically unstable range of the Himalayan orogen. Despite serving as a border between the lowland (Terai) and Himalayan range, it remains underrepresented in both biodiversity assessments and conservation planning in Nepal. Our findings suggest the need for a robust and targeted species research program and to prioritise this landscape for conservation actions.

Key words: Bent-toed gecko, Himalayas, integrative taxonomy, khasiensis group, Siwalik

Although crocodyliforms from the Campanian–Maastrichtian of North America have received considerable attention, taxa occurring earlier in the Cretaceous have only recently begun to be more thoroughly studied. Of particular interest amongst these recent discoveries is the heterodont neosuchian Wannchampsus kirpachi Adams 2014 and the similar, undescribed ‘Glen Rose Form’ (USNM 22039). Both hold an unclear phylogenetic position, either forming a clade sister to Atoposauridae, a group of small, heterodont neosuchians from the Jurassic and Cretaceous of Laurasia, or to Paralligatoridae, a clade of larger, platyrostral, homodont neosuchians from the Cretaceous of Asia and North America. Here we describe a new species of diminutive, heterodont neosuchian, Thikarisuchus xenodentes gen. et sp. nov., from the early–middle Cenomanian Vaughn Member of the Blackleaf Formation of southwest Montana. The specimen includes cranial, mandibular, axial, and appendicular elements in articulation and dense concentration. It is recovered in a sister relationship with Wannchampsus and USNM 22039. We propose the name Wannchampsidae (clade nov.) for this group of small, heterodont neosuchians endemic to the Cretaceous of North America. Wannchampsidae is more confidently recovered sister to Atoposauridae due to the recognition of new synapomorphies. The new taxon provides greater clarity on the potential diet and paleoecology of Wannchampsidae and Atoposauridae and displays similar craniomandibular and dental characteristics to the notosuchian group Uruguaysuchidae, strongly suggesting these neosuchian groups were also omnivorous or insectivorous and terrestrially adapted, respectively representing a unique diet and reversion to terrestriality within Neosuchia.

CROCODYLOMORPHA Hay, 1930 (sensu Nesbitt, 2011)

CROCODYLIFORMES Hay, 1930 (sensu Clark, 1986)

NEOSUCHIA Clark in Benton and Clark, 1988

Type Genus—Wannchampsus kirpachi Adams, 2014.

Etymology—'The family of Wannchampsus.’ The stem Wannchamps- is based on the designated type genus Wannchampsus. -idae, is a Latin patronymic suffix.

Under Article 29.2 of the Zoological Code, the suffix -idae denotes a family rank within the family-group.

Phylogenetic Definition—Branch-based clade comprising all taxa more closely related to Wannchampsus kirpachi Adams, 2014 than to Theriosuchus pusillus Owen, 1878 or Shamosuchus djadochtaensis Mook, 1924.

Locality, Horizon, and Age—Vaughn Member of the upper portions of the Blackleaf Formation (early–middle Cenomanian). Material originates from The Mound (BL-9) in the Lima Peaks area of southwest Montana, southeast of the town of Lima, MT and was recovered on the surface in float or was surface screened, sifted, and later identified/recovered within the lab.

Diagnosis—A small neosuchian crocodyliform with the following unique combination of characters (autapomorphies denoted by an asterisk): longitudinal groove on posterior dentary laterally adjacent to dentary toothrow for reception of posterior maxillary teeth*; extreme mesiodistal elongation and low apicobasal height of posterior ‘low crowned’ maxillary and dentary teeth*; development of frontoparietal midline ridge into a symmetric, elongate hexagonal boss at frontal-parietal suture*; extension of lateral angular ridge onto lateral surface of posterior dentary*; oreinirostral snout; anteriorly oriented external nares; small, anteroposteriorly aligned sulcus present posterior to triple junction of sutures of the premaxilla, maxilla, and nasals; orbitonasal sulcus (sensu Turner, 2015) on lateral surface of maxilla; occlusal pit on palatal process of maxilla adjacent to 4th and 5th maxillary teeth; ventral surface of posterolateral portion of palatal process of maxilla possesses a shallow groove that accommodates some posterior dentary teeth; internal choana bounded almost entirely by pterygoids, with palatines contributing to anterior margin; procoelous cervical, dorsal, and caudal vertebrae; humeral head convex, with the center of the humeral head positioned proximally above the rest of the surface; humerus proximal to deltopectoral crest strongly deflected medially at ∼45° compared with humeral shaft; highly reduced postacetabular process of ilium; elongate proximal process on fibula.

Etymology—After “thikari,” the diminutive form of the Greek word “thiki” meaning sheath, referring to the way in which the posterior maxillary teeth ‘sheath’ within the longitudinal groove on the dentary adjacent to the dentary toothrow as well as the diminutive size of the specimen, and “suchus,” from the Latinized form of “soukhos,” Greek for crocodile. After “xeno,” Greek for strange, and “dentes,” Latin for teeth, referring to the strange heterodont dentition and extremely mesiodistally elongate and apicobasally low posterior teeth.

Harrison J. Allen, Eric W. Wilberg, Alan H. Turner and David J. Varricchio. 2025. A New, diminutive, heterodont Neosuchian from the Vaughn Member of the Blackleaf Formation (Cenomanian), southwest Montana, and Implications for the Paleoecology of heterodont neosuchians. Journal of Vertebrate Paleontology. e2542185. DOI: doi.org/10.1080/02724634.2025.2542185 [22 Sep 2025] 

Lucio M. Ibiricu, Matthew C. Lamanna, Bruno N. Alvarez, Ignacio A. Cerda, Julieta L. Caglianone, Noelia V. Cardozo, Marcelo Luna and Rubén D. Martínez. 2025. Latest Cretaceous megaraptorid theropod Dinosaur sheds light on megaraptoran evolution and palaeobiology. Nature Communications. 16: 8298. DOI: doi.org/10.1038/s41467-025-63793-5 [23 September 2025]