Waif or hybrid? Observation records of rare coloration grouper in Djibouti

Abstract

We observed groupers with an unusual color pattern in Ghoubet-Al-Kharab Bay, Djibouti, on two occasions in 2014 and 2020. It matches the field observation of a juvenile Cephalopholis formosa in India in 1980. If this is the case, our observation represents a major range extension for C. formosa. Alternatively, based on the intermediate coloration of the specimens and sightings, we propose that they may be hybrids of C. formosa and C. oligosticta. We present two possible scenarios that may have facilitated hybridization: rarity and overlapping ranges in Djibouti with self-recruitment or rarity and overlapping ranges in another location (e.g., Socotra or the Arabian Sea) with long-distance larval dispersal to Djibouti. This hybridization is possible given the genetic similarity between the two putative parent species and because similar hybridization cases have been recorded within this genus and family elsewhere. However, both of these scenarios would require a range extension for one or both parent species as they are not previously known to overlap. Nevertheless, further field observations and genetic studies are required to verify the proposed identification of the putative hybrid and test the presented scenarios.