Repeated coastal observations and molecular confirmation of Alatina grandis (Cubozoa: Alatinidae) in the Gulf of Aqaba, Red Sea

Abstract

Cubozoans are rarely documented in the Red Sea, and the taxonomic identity of large alatinid medusae previously reported from the Gulf of Aqaba has remained uncertain. Historical observations from Eilat in 1997 and 2000 were reported as Carybdea alata, although their exceptionally large size was recognized as being within the range of C. grandis (currently Alatina grandis); unresolved carybdeid taxonomy at the time prevented a definitive species-level assignment. Following more than two decades without documented observations, five large alatinid medusae were recorded on separate occasions along the Eilat coastline between July 2025 and August 2026. One specimen was collected, while high-resolution in situ photographs and video recordings of live medusae provided material for morphological assessment. Diagnostic morphological characters were consistent with Alatina grandis, and molecular analysis of the collected specimen independently confirmed its identity as A. grandis. These findings provide the first molecular confirmation of A. grandis from the Gulf of Aqaba and the Red Sea and establish the identity of the alatinid medusae documented during the recent series of observations. The clustering of five observations within one year, following more than two decades without documented occurrences, raises questions regarding the temporal occurrence and distribution of this rarely reported cubozoan in the northern Red Sea.