Epinephelus tankahkeei, Wu & Qu & Lin & Tang & Ding, 2020

Wu, Haohao, Qu, Meng, Lin, Hungdu, Tang, Wei & Ding, Shaoxiong, 2020, Epinephelus tankahkeei, a new species of grouper (Teleostei, Perciformes, Epinephelidae) from the South China Sea, ZooKeys 933, pp. 125-137 : 125

Epinephelus tankahkeei sp. nov. Figs 1 , 2 ; Table 1

Type material.

Holotype: ZMUA-eptan06, 244.5 mm SL, Caught in Yongxing Island, Sansha, Hainan, 2 April 2017. Paratypes: ZMUA-eptan01, 111.0 mm SL, China, purchased at a fish market in Xiamen, Fujian, China, 1 September 2011, reported as collected in the south Taiwan Strait; ZMUA-eptan02, 233.2 mm SL, purchased at the Bashi market in Xiamen, Fujian, China, 22 August 2016, reported as collected in the south Taiwan Strait; ZMUA-eptan03, 215.4 mm SL, collected with the ZMUA-eptan02; ZMUA-eptan04, 262.5 mm SL, purchased at a fish market in Shenzhen, Guangdong, China, 15 February 2017, reported as collected in the South China Sea; ZMUA-eptan05, 232.6 mm SL, collected with the holotype; ZMUA-eptan07, 252.9 mm SL, purchased at a fish market in Shenzhen, Guangdong, China, 1 July 2017, reported as collected in the South China Sea; ZMUA-eptan08, 274.2 mm SL, China, purchased at a fish market in Xiamen, Fujian, China, 31 July 2018, reported as collected in the south Taiwan Strait. ZMUA-eptan09, 186.5 mm SL, China, purchased at a fish market in Haikou, Hainan, China, 22 March 2019, reported as captured using a trawl net in Mulan Bay, Wenchang, Hainan.

Diagnosis.

Epinephelus tankahkeei sp. nov. can be distinguished from all other Indo-Pacific Epinephelus species by the following characteristics: dorsal-fin rays XI, 16-18 (vs. 14-15 in Epinephelus gabriellae ); anal-fin rays III, 8; pectoral-fin rays 16 or 17; lateral-line scales 47-51 (vs. 65-72 in Epinephelus polylepis ); caudal fin convex (vs. slightly emarginate or truncate caudal fin in E. chlorostigma , Epinephelus areolatus , Epinephelus bleekeri , and Epinephelus geoffroyi ); anal fin rounded (vs. angular anal fin in E. chlorostigma , and E. geoffroyi ); membranes of spinous portion of dorsal fin slightly incised; head (except chest), body (except abdomen), and fins (pectoral fin spotted only basally) with numerous, irregular, close-set, dark brown spots, becoming more widely spaced on the lower part, the ground color forming a pale network (vs. lager spots in Epinephelus miliaris , and E. areolatus ); rear margin of the caudal fin without a narrow white line (vs. a clear white margin posteriorly on the caudal fin in E. chlorostigma , and E. areolatus ).

Description.

Dorsal-fin rays XI, 16 (16-18); anal-fin rays III, 8; pectoral-fin rays 16 (16 or 17); lateral-line scales 51 (47-51); lateral scale series 123 (111-123); gill rakers 10 (10-11) +15 (14-16); vertebra 24; body slightly elongated and body depth less than head length. Body depth contained 3.2 (3.0-3.2) in standard length. Body laterally compressed and body width 2.6 (2.1-2.6) in body depth. Head length 2.7 (2.5-2.7) in SL; orbit diameter 6.1 (4.9-6.8) in head; snout length 3.8 (3.6-4.0) in head. Dorsal profile of head nearly straight except at the snout with a slight notch before eyes. Interorbital region convex, width 6.3 (5.6- 7.2) in head; preorbital depth 7.8 (7.8-11.3) in head; caudal-peduncle length 1.9 (1.8-2.2) in head; caudal-peduncle depth 3.3 (3.2-3.7).

Mouth large and lower jaw slightly projecting and oblique. Lower jaw 3.4 (3.4-3.9) in head length; upper jaw 2.4 (2.3-2.5) in head. Maxilla slightly extending to rear edge of eye and posterior edge of maxilla slightly rounded. Maxilla width 8.1 (7.9-9.2) in head. One or two pairs of canine teeth at anterior part of the upper and lower jaw. Teeth of lower jaw form two rows and expand anteriorly into three rows; teeth in the outer side are larger than the inner side. Villiform teeth present on vomer and palatines. Tongue slender and sharp at tip. Longest gill raker was greater in length than longest gill filament. Nostrils round and posterior nostril larger than anterior nostril. Anterior nostril with a membranous flap.

Three spines on operculum, topmost and undermost small, the middle the largest. Tip of middle spine extending farther towards tail than tip of lower spine. Upper edge of opercular membrane slightly convex coming to a rounded point posteriorly. Preopercle rounded with four to five prominent spines at angle and with numerous fine serrae while increasing in size downward. Lateral line starting from posterior opercle and slightly arched over pectoral region. Scales on head, thorax, abdomen, anterodorsal part of body and fin membranes weakly ctenoid. Auxiliary scales absent. Small scales present on inner margins of dorsal, pectoral, pelvic, and caudal fins and not extending to the rear margin area.

Origin of dorsal fin before pectoral-fin base. Membranes of spinous portion of dorsal fin slightly incised. First dorsal spine contained 1.9 (1.6-2.0) times in second spine; second spine 1.2 (1.2-1.5) times in longest spine (third and fourth spine); longest spine contained 2.6 (2.6-3.1) in head length. Longest soft dorsal ray 2.4 (2.3-2.8) in head. Anal-fin origin below origin of first soft dorsal ray. First anal spine 2.0 (1.9- 2.3) times in second anal spine; second anal spine 1.2 (1.1- 1.4) times in third anal spine; third anal spine longest 3.5 (3.0-4.1) in head. Longest anal-fin rays 2.1 (1.9-2.5) in head. Caudal fin convex, 1.7 (1.6-2.0) in head. Middle pectoral rays longest, 1.8 (1.7-1.9) in head and reaching to base of 9th dorsal spine. Origin of pelvic fin slightly posterior to pectoral-fin base.

Coloration in life

(based on photographs of the fresh holotype and paratypes). Head (except chest), body (except abdomen), and fins (pectoral fin only basally) with numerous, irregular, close-set, dark brown spots becoming more widely spaced on the lower part and with the ground color forming a pale network (Fig. 1a ); dorsal fin, caudal fin and anal fin dark brown; pectoral fin translucent with reddish brown to light yellowish-brown; body sometimes with four faint, irregular, discrete dark bars; rear margin of the caudal fin without a narrow white line.

Coloration in preservative.

Body yellowish-brown to tan with close-set spots remaining prominent or faded (Fig. 1b, c ). Dorsal, caudal, and anal fins dark brown. Pectoral fin pale and opaque.

Genetic analyses.

Mitochondrial COI gene sequences were obtained from nine specimens of E. tankahkeei . Several sequences of related species were also sequenced in this study or obtained from GenBank. E. tankahkeei has 13 species-specific mutations at nucleotide positions 126, 216, 222, 249, 276, 372, 414, 519, 525, 528, 558, 567, and 576 (Table 2 ). The intraspecific mean distance of E. tankahkeei was 0.0028. The interspecific mean distances indicated that E. tankahkeei differs from E. chlorostigma by 0.0621, from E. polylepis by 0.0771, from E. gabriellae by 0.1263, from E. miliaris by 0.0904, from E. geoffroyi by 0.1219, and from E. areolatus by 0.0855 (Table 3 ). Phylogenetic trees using both maximum likelihood and Bayesian inference showed almost complete agreement, with E. tankahkeei forming a monophyletic clade that excluded all other closely related species (Fig. 3 ).

Distribution and habitat.

The new species was recently observed in the South China Sea and Taiwan Strait. Similar to other congeners, E. tankahkeei is a reef-associated species that feeds on fishes and invertebrates.

Etymology.

Epinephelus tankahkeei is named after Tan Kah Kee (1874-1961), who was a famous overseas Chinese educator, philanthropist, and social activist and the founder of Xiamen University and Jimei School, in honor of his significant contribution to the motherland.

Figures

Figure 1. Epinephelus tankahkeei a holotype, ZMUA-eptan 06, 244.5 mm SL, Xisha Islands from the South China Sea b preserved holotype c paratype, ZMUA-eptan 02, 233.2 mm SL, purchased at the Bashi market in Xiamen, Fujian, China, 22 August 2016.

Figure 2. Epinephelus tankahkeei sp. nov. Radiograph of paratype ZMUA-eptan 08, 274.2 mm SL.

Figure 3. Bayesian phylogenetic tree of Epinephelus tankahkeei and closely related fish species. Numbers above nodes are Bayesian posterior probability values (left) and ML bootstrap values above 50 (right).