Annual and lunar-cycle-related breeding rhythmicity in the acorn barnacle Tetraclita kuroshioensis Chan, Tsang & Chu, 2007 (Cirripedia: Balanomorpha: Tetraclitidae) in Okinawa, Japan.

The article focuses on the reproductive biology of the barnacle *Tetraclita kuroshioensis* in the intertidal zone of Okinawa, Japan, examining gonadal development, egg brooding, and larval release in relation to environmental factors. The study found that the species has a seven-month breeding season from March to September, coinciding with water temperatures above 21 °C and long-day photoperiods. While ovarian development showed little variation across tidal heights or lunar phases, larval brooding and release were influenced by lunar cycles—particularly the new moon—and tidal height, with greater brooding observed at upper and middle intertidal zones during peak and late reproductive periods. These findings suggest that seasonal temperature, photoperiod, lunar phases, and tidal cycles collectively regulate the reproductive rhythms of *T. kuroshioensis* in its subtropical habitat.