First record of the adult of Cymbalcloeon confirming its position in Baetidae (Insecta, Ephemeroptera).

Background: The nymphs of Cymbalcloeon sartorii Suttinun et al., 2020 present several unusual characters such as having only three pairs of ventral gills. The imaginal stage of this recently described genus remains unknown. New information: In Spring 2025, tens of nymphs as well as morphologically and molecularly associated adults of this species were collected in southwestern China. This represents the first recorded occurrence of the genus in China, and indeed, the first report outside Thailand. The male imagos have tiny bodies, clear median longitudinal ridge on mesonotum, one pair of wings without any marginal intercalary veins, relatively long apical segment of styliger, and distinct penis cover. The morphology of this species shows it is close to Baetopus Keffermüller, 1960 in the subfamily Cloeoninae. However, it lost some key structures, like marginal intercalaries, hindwings and most gills.