Yunnan Province is a hotspot for camaenid snail diversity, a fact recognized since the pioneering malacological work of the nineteenth century. Yet the mountains around Yuxi City have received remarkably little attention from researchers studying land snails. It was there, in a forest patch on a limestone karst mountain, that collector Yue-Ming He first encountered the unfamiliar snails climbing on trees. The specimens were gathered in August 2025 from a single site at coordinates 24.3658°N, 102.8294°E, preserved in 95 percent ethanol, and measured with a vernier caliper before being photographed under a stereomicroscope. The holotype and paratypes now reside at the Museum of Biology at Nanchang University.

The shell alone is eye-catching. It is conical and thin, with five to six regularly growing whorls that are slightly convex on the upper side and flat on the base, and it carries distinctive red-brown bands above the periphery, where an acute keel gives the outline a sharp edge. That combination of a pointed peripheral keel and colored banding immediately recalled certain species of Ganesella, a genus of primarily Oriental distribution that includes 28 valid species in China, whose members range from conical to flattened-conical shells. It also resembles shells assigned to the genera Plectotropis, Satsuma, and Globotrochus. But superficial similarity is precisely where the story gets interesting, because the researchers went well beyond the shell.

To resolve the animal’s true identity, the team dissected the reproductive system and extracted genomic DNA from a piece of pedal muscle of the ethanol-preserved holotype. They amplified and sequenced three molecular markers widely used in snail systematics: the mitochondrial protein-coding gene COI, the mitochondrial ribosomal gene 16S, and the nuclear ribosomal spacer ITS2. Standard primers and thermal cycling protocols produced clean amplicons, which were purified, bidirectionally Sanger sequenced, and assembled before being aligned with MAFFT and trimmed with trimAl. Saturation tests confirmed that the markers had not diverged so far that their signal was obscured, an important quality check before building evolutionary trees.

The comparative dataset was substantial. The researchers retrieved 85 sequences from GenBank representing morphologically similar and potentially related taxa across the Camaenidae, and constructed two concatenated matrices, one of 2,160 base pairs combining all three markers and a second of 1,518 base pairs using only 16S and ITS2, because COI data were unavailable for every taxon. Both datasets contained the same 39 terminals. Partition schemes and substitution models were selected with PartitionFinder 2, and the trees were rooted with the widespread Roman snail, Helix pomatia, from the family Helicidae. Maximum likelihood analyses in IQ-TREE with 5,000 ultrafast bootstrap replicates and Bayesian inference in MrBayes were run in parallel, with convergence confirmed by standard diagnostic criteria.

The verdict from the trees was unambiguous. Both methods and both datasets recovered the new snail as a distinct lineage within the subfamily Bradybaeninae, forming a well-supported clade together with the Asian genera Bradybaena, Ezohelix, Karaftohelix, and Acusta, with maximum likelihood bootstrap support of 94 percent and a Bayesian posterior probability of 0.99. Genetic distances underscored that separation. Uncorrected p-distances between the new genus and those four related genera ranged from 18.1 to 21.0 percent for COI and 20.9 to 27.8 percent for 16S, values comparable to the distances separating the established genera from one another, while ITS2 divergence of 4.8 to 5.9 percent also exceeded the typical within-genus variation of its relatives.

The anatomy supplied the clinching characters, and one of them is genuinely without precedent. The penis is distinctly longer than the atrium and vagina and lacks both an epiphallus and a flagellum; its wall is double-layered and its inner surface carries no penial pilasters and no penial verge. The penial retractor muscle is thick and short. The dart sac contains a single curved love dart, a calcareous structure some snails fire during courtship, and three slightly convoluted mucus glands are present. Most strikingly, the animal possesses a distinct muscle arising from the right side of the dart sac, with its distal end attached to the dart sac’s ventral side and an internal structure of numerous parallel septa. The authors identified this as a dart sac retractor muscle, a structure that has not been reported in any other known species, and they regard it, together with the sharply keeled shell periphery, as the key diagnostic feature of the new taxon.

Formal naming followed. The genus name Yuyao refers to beautiful jade stones, echoing the color and texture of the animals, with the vernacular name yu yao luo. The species epithet heyuemingi honors Yue-Ming He, who discovered the snail and assisted with the field survey; the Chinese vernacular name is He shi yu yao luo. The holotype measures 17.82 millimeters in shell length, 18.31 millimeters in shell width, and 14.64 millimeters in shell height. Comparisons with named relatives confirmed the diagnosis against a long list of look-alikes: the new species differs from Ganesella capitium, Ganesella carinella, and Globotrochus onestera in its genital architecture; from Ganesella rhombostoma and Ganesella emma in whorl number and band position; from Satsuma stenozona in lacking a penial caecum and in its dart sac musculature; and from Plectotropis brevibarbis and Plectotropis yonganensis in a combination of penial and dart sac characters. Even species known only from shells, such as Ganesella trochacea, Aegista packhaensis, and Globotrochus mellea, can be separated by the red-brown banding and sharp keel.

Beyond the description of one snail, the study carries a broader message about how biodiversity is cataloged. The authors argue that the Ganesella-like shell shape seen in species from China and Southeast Asia has likely arisen repeatedly through convergent evolution in multiple unrelated genera, which means the taxonomy of Ganesella, historically built almost entirely on shell characters in China, remains ambiguous. They flag specific cases in need of re-examination, including Ganesella subdicusa, described from fossils without study of internal shell structure, and Ganesella halabalah, whose shell closely resembles that of Pseudopartula khoai. Relying on shells alone, they conclude, may make it difficult to determine which genus these species truly belong to, and anatomical and molecular work is needed to put the classification on firmer ground.

There is also a conservation note that lends the discovery urgency. During fieldwork, the team observed degradation and reduction of natural habitat within the species’ range. Yuyao heyuemingi is known only from a small forest patch at the type locality, and subfossil shells occasionally found buried in soils on the surrounding mountains hint that the snail once ranged more widely. Recent drought in Yunnan and land cultivation by farmers near the site may be driving a contraction of that range. Given how little attention land snails in the mountains of Yuxi City have received, the authors stress that further surveys are essential both to understand the survival status of these animals and to improve the prospects of protecting them, before more of Yunnan’s hidden snail diversity disappears with the forests that harbor it.

Subject of Research: Taxonomic description of a new genus and species of camaenid land snail from Yunnan, China

Article Title: A new genus and new species of Bradybaeninae ( Gastropoda , Camaenidae ) from Yunnan Province, China

Article References: Wang, P., Wang, Z.-Y., Yang, J.-M., Zheng, H., Lu, Y.-Z., Yang, S.-Z., Zheng, J., & Xiang, H.-Q. (2026). A new genus and new species of Bradybaeninae (Gastropoda, Camaenidae) from Yunnan Province, China. Zoosystematics and Evolution, 102(5), 1159-1170. https://doi.org/10.3897/zse.102.182198

Image Credits: AI Generated

DOI: 10.3897/zse.102.182198

Keywords: land snails, Camaenidae, Bradybaeninae, new genus, new species, Yunnan, China, karst forest, molecular phylogeny, taxonomy, convergent evolution, conservation