Morphological characteristics of soft coral Sarcophyton serenei (Tixier-Durivault,1958) in Nha Trang Bay

Abstract

Soft corals are integral components of tropical coral reef ecosystems, contributing significantly to biodiversity and providing substantial economic value as ornamental organisms and sources of bioactivecompounds. As such, accurate classification of soft coral species is essential for the sustainable managementand exploitation of these resources. Sarcophyton serenei, a soft coral species found in Nha Trang Bay, is commercially important for the marine ornamental trade and the extraction of bioactive substances. Thisspecies is characterized by a bright yellow-brown to gray-brown coloration, short and semi-contractedpolyps, and a smooth capitulum with numerous folds along the periphery of the disc. The surface of the discis rough and lacks mucus secretion, distinguishing it from other species in the genus Sarcophyton. Themorphological characteristics of the sclerites, including those from the anthocodiae, tentacles, capitulum,and stalk were examined and found to match the descriptions provided by Tixier-Durivault (1958) andDautova & Savinkin (2013), with some minor differences from the classification key of Verseveldt (1982).Scanning electron microscopy (SEM) was applied to study the surface features of the sclerites, revealingdetailed structures such as warts, spines, and granules. Additionally, rDNA ITS2 sequencing was used to identify the coral’s algal endosymbionts, which belongs to the genus Symbiodinium, specifically clade C. Thenucleotide sequence analysis showed minimal variation among the symbionts, indicating a high degree of similarity within this clade. These findings contribute to the broader understanding of S. serenei and itsecological role in coral reef ecosystems, while also supporting the need for effective conservation andsustainable utilization strategies.