Epinephelus flavocaeruleus ( Lacepède, 1802 )

Loh, Kar-Hoe, Poong, Sze-Wan, Du, Jianguo, Ong, Joyce Jia Lin, Zheng, Xinqing, Li, Yuan & Hu, Wenjia, 2024, First record of the blue-and-yellow grouper Epinephelus flavocaeruleus (Lacepède 1802) (Perciformes: Epinephelidae) from the Borneo waters, Malaysia, Zootaxa 5550 (1), pp. 133-144 : 135-139

Epinephelus flavocaeruleus ( Lacepède, 1802)

Blue-and-yellow grouper

Fig. 1 a & b, Table 1

Specimens examined: The color pattern of the Malaysian specimens identified as E. flavocaerules was similar to the species description in Heemstra and Randall (1993). The five specimens were (n=4, G2, G3, G4, and G5), 470–540 mm SL (540–630 mm TL), and 2.66–4.82 g total weight, all males. G1, with only the head part and caught from the Borneo waters of Sabah, was purchased from a local fish market, NSK (KL), on 28 December 2021 and 21 February 2022 .

Description of the Malaysian specimens. Description: E. flavocaeruleus is an incredibly colorful grouper. The adults have yellow dorsal fin, pectoral fin, pelvic fin, and anal fins ( Fig. 1a), body dark gray or purplish brown with yellow reduced to small areas on the head and margin of spinous dorsal fin, distal third of pelvic blackish margin. Upper jaw lip often yellow ( Fig. 1b). Large adults were losing all the yellow color, becoming deep blue to black, and yellow in the body. The dorsal and anal fins have a very narrow yellow margin for the fourth specimen, with 588 mm TL. Dorsal rays XI, 16 or 17; anal rays III, 8; pectoral rays 17 to 20. Morphometric and meristic traits of E. flavocaeruleus are given in Table 1 . Body depth 2.27–2.57 in % SL; Head Length 2.46–2.83 in % SL; Pre-anal length 1.57–1.75 in % SL; Pre-orbital length 5.39–6.03 in % HL; Eye diameter 6.70–8.20 in % HL. Standard length 1.15–1.17 in % TL.

Distribution: E. flavocaeruleus was previously identified in the Indian Ocean, the Andaman Sea, and Sumatra, Indonesia. This study presents the first record of its presence in Borneo waters, extending the distribution range of E. flavocaeruleus eastwards from the Andaman Sea to the Borneo waters of Sabah, Malaysia ( Fig. 2).

The 27 grouper specimens were classified as 13 species based on external morphology, which was consistent with the species names found in both the GenBank BLAST and BOLD databases. DNA sequences from the five specimens were submitted to GenBank with the accession numbers OR977058–977062 ( Table 2 ). There were a total of 200/630 bp of variable sites and 163/630 bp of parsimony-informative sites after aligning the sequences. The average base composition obtained was 24.1% A bases, 28.5% C bases, 18.9% G bases, and 28.5% T bases. However, there were a total of 16/630 bp of variable sites and 9/630 bp of parsimony-informative sites for E. flavocaeruleus (n=10). The average base composition obtained was 23.8% A bases, 29.7% bases, 19.5% G bases, and 27.0% T bases. Figure 3 shows the Maximum Likelihood (ML) tree inferred from COI barcodes for some related Epinephelus species. Bootstrap values <50% are not shown, and the scale bar indicates percent divergence calculated under the GTR +G +I.

The ML phylogenetic tree reconstructed based on GTR +G +I is shown in Figure 3.All species are monophyletic, with bootstrap values between 62 and 100%. All five E. flavocaeruleus samples (OR977058– OR977062) were clustered together with the E. flavocaeruleus reference sequences from GenBank (KM226268 India, MF185511 China, MH707753 South Africa, JF493441 Mozambique, and JQ349963 Madagascar) with a 61–100% bootstrap value. Genetic distances between grouper species based on the 630 bp COI consensus sequences and the respective reference sequences with the K2P model are given in Table 3 . The intraspecific nucleotide distances for E. flavocaeruleus ranged from 0.002 –0.027. However, the specimens from Malaysia recorded low intraspecific genetic variation ranging from 0.000 –0.002, whereas the samples from Madagascar (JQ349963) and South Africa (MH707753) were more genetically distant (0.011 –0.025). The interspecific differences between other grouper species of the genus Epinephelus ranged from 0.002 –0.168, with the largest genetic distance recorded between E. heniochus and E. sexfasciatus at 0.168.

The TCS haplotype network analysis of E. flavocaeruleus and E. cyanopodus based on the COI marker is shown in Figure 4. The Malaysian samples of E. flavocaeruleus belong to two haplotypes, G1 and G2, with only a 1 bp difference between them. The E. flavocaeruleus haplotypes from South Africa (MH707753), Madagascar (JQ349963), and the Seychelles (SAIAB441-06) had more genetic variation. In contrast, another E. flavocaeruleus haplotype from the Seychelles (SAIAB149-06) is only 2 bp different from haplotype G1.Among the seven haplotypes of E. flavocaeruleus , haplotype G1 is the most common and is reported from Malaysia, South Africa, Mozambique, India, the Seychelles and Indonesia. Haplotype G2 is reported in two samples from Malaysia and the South China Sea, while the other five haplotypes are restricted to the western Indian Ocean. The network indicates a very close genetic relationship between E. flavocaeruleus and E. cyanopodus , with only a 1 bp difference between haplotype MF185487 ( China, New Caledonia, Japan, India, and Australia) and G1 as summarized in Table 4 .