Fig 1.
Population survey areas (Areas 1 and 2; B, C) within the Hwanseongul Cave, where mating and egg laying of Onychodactylus koreanus, a subterranean breeder, were previously observed.
The environmental DNA (eDNA) sampling sites are also shown in the schematic diagram (A).
Fig 2.
Population survey of adults (A) and larvae (B), and environmental DNA (eDNA) detection of Onychodactylus koreanus at the first (C) and second (E) sampling sites over 14 months between April 2024 and June 2025.
The first site (D) was approximately 60 m inside the cave, and the second site (F) was at the cave entrance.
Fig 3.
Primary spawning site (A) of Onychodactylus koreanus, a subterranean breeder, and their eggs observed on December 13, 2024 (B) and those recorded on July 28, 2025 (C).
The primary spawning site is located on the rock face underwater, indicated by a red arrow (A). At the bottom, ovulated (D) and oviposited (E) abdomens of females are shown.