Most <i>Pocillopora damicornis</i> around Yaeyama Islands are <i>Pocillopora acuta</i> according to mitochondrial ORF sequences

Abstract

Pocillopora acuta Lamarck, 1816, that had long been treated as a junior synonym of Pocillopora damicornis (Linnaeus, 1758), was resurrected in Australia based on differences in the mitochondrial open reading frame (ORF) sequences with 6-8 nucleotide differences in 840 bp (Schmidt-Roach et al. 2014). To investigate whether P. acuta exists in Japan, we collected 73 colonies with P. damicornis-like morph from eight locations that are a maximum of 44.4 km apart around Yaeyama Islands (24°13′-24′ N, 123°41′-124°07′ E), southwestern-most islands of Japan, and analyzed their mitochondrial ORF sequences. We found that the DNA sequences of 72 of the 73 samples were identical to those of Australian P. acuta (e.g. JX985592-6; they are still registered as P. damicornis "type beta SSR-2012"), while the remaining one gave sequences identical to those of Australian P. damicornis (e.g. JX985597-601). Thus, DNA typing revealed that P. acuta exists abundantly at least around Yaeyama Islands. According to Schmidt-Roach et al. (2014), Pocillopora acuta has more elongated, sharper, and thinner branchlets than P. damicornis, and polyp of P. acuta looks like a brown ring. Hence, we propose a Japanese name "hosoeda-hanayasai" for P. acuta after the thinnest branchlets ("hosoeda") among all Pocillopora spp. ("hanayasai"). However, two species from Yaeyama Islands cannot be distinguished by these characteristics (Figure 1). Besides, size of columellae and density of spinular are highly variable even in a single corallum in both two species. Therefore, the ORF sequences appear to be the only measure to distinguish the two species in Yaeyama Islands. This study certainly highlights the importance of identifying P. acuta in Japan because previous studies on "P. damicornis" might have included P. acuta. Further studies may disclose whether these "P. damicornis" morphs are indeed P. damicornis or include P. acuta.

New evidence shows that Pocillopora ‘damicornis-like’ corals in Singapore are actually Pocillopora acuta (Scleractinia: Pocilloporidae)

“…Pocillopora acuta Lamarck, 1816, p. 274; Schmidt-Roach et al 2014a, p. 17; Schmidt-Roach et al 2014b, p. 11; Kitano et al 2015, p. 21; Mayfield et al 2015, p. 1.…”

“…Further north at the Yaeyama Islands, Japan, P. damicornis is present but is likely rare relative to P. acuta (Kitano et al 2015). Despite that, P. damicornis is the only Pocillopora species detected along mainland Japan to date (Pinzón et al 2013).…”

Microsatellite markers for multiple Pocillopora genetic lineages offer new insights about coral populations

“…Clonal replicates were detected at both sites in Type 5 (Table 3 ). In addition, the population size of Type 5, based on genetic analysis appears to be large in Miyako Island, as in the Yaeyama Islands, where P. acuta exists abundantly 23 . Mean values of genetic indices across loci for each lineage/site with large numbers of multilocus genotypes (Types 1, 3, 5 at Ueno, Type 5 at Yoshino) are shown in Table 3 .…”

Data on coral species occurrences in Japan since 1929

“…We thus applied the names used by Sugihara et al (2015) if differences were found. Other revisions were performed by referring to recent systematics (Arrigoni et al, 2016;Benzoni, 2006;Benzoni, Arrigoni, Waheed, Stefani, & Hoeksema, 2014;Benzoni, Stefani, Pichon, & Galli, 2010;Kitano, Nagai, Ueno, & Yasuda, 2015;Lagman, Licuanan, & Chen, 2018;Nomura & Suzuki, 2013; or past occurrence records (Uchida & Fukuda, 1989;Veron, 2000;Tachikawa, 2005;ReefCheck Kushimoto, 2014;Yasuda et al, 2014) as necessary.…”