Lates uwisara, Pethiyagoda, Rohan & Gill, Anthony C., 2012

Pethiyagoda, Rohan & Gill, Anthony C., 2012, Description of two new species of sea bass (Teleostei: Latidae: Lates) from Myanmar and Sri Lanka, Zootaxa 3314, pp. 1-16 : 6-8

Lates uwisara , new species

( Fig. 3 )

Material examined: holotype, ANFC H. 6316-10, 353 mm SL, Myanmar, “river estuaries between Yangon and Sittang”, October 2005; paratypes, ANFC H.6316-09, 363 mm SL; ANFC H. 6316-11, 332 mm SL; ANFC H. 6316- 12, 350 mm SL, same collection data as holotype.

Diagnosis. Lates uwisara is distinguished from L. calcarifer by possessing 7 (vs. 6) scales between the base of the third dorsal-fin spine and the lateral line; and having a lesser eye diameter (4.4‒4.7% SL, n=3; vs. 4.8‒6.9% SL, n=25). It differs from L. lakdiva by having a greater body depth (28.4‒34.5% SL, vs. 26.6‒27.6% SL), a longer dorsal-fin base (43.3‒45.0% SL, vs. 41.1‒43.2% SL), a lesser eye diameter (4.4‒4.7% SL, vs. 5.5‒5.6% SL), and by possessing 7 (vs. 5) rows of scales between the base of the third dorsal-fin spine and the lateral line. It is distinguished from L. japonicus by having the third anal-fin spine shorter (vs. longer) than the second; a shorter caudal peduncle (15.8‒17.6 % SL, vs. 18.2‒20.2% SL) and a greater preanal distance (72.9‒75.6% SL, vs. 67.5‒72.3% SL).

Description. See Table 1 for proportional measurements. Body compressed (body width 49.3‒50.4% body depth), its depth 3.1‒3.5 times in SL, deepest at dorsal-fin origin. Dorsal profile concave in interorbital region, rising steeply (convex) thereafter to dorsal-fin origin. Head moderately acute, its length 2.8 times in SL. Eye oval, height less than width, eye diameter 7.5‒8.6 times in head length. Snout 4.7‒5.2 times in head length. Interorbital space 114‒122% eye diameter. Mouth oblique, lower jaw projecting beyond upper one when closed. Maxilla deep, its depth 104‒120% eye diameter, extending posterior to level of eye. Villiform teeth present on jaws, palatines, pterygoids and vomer. Tongue smooth. Three sharp, strong spines on inferior margin of preoperculum, first antrorse; a retrorse spine at angle of preoperculum. Preoperculum posterior margin with 26‒34 serrae. A sharp spine at angle of operculum. Seven branchiostegal rays. Inferior edge of infraorbitals 1 and 2 finely serrated. Nares level with middle of eye, separated from eye by distance less than diameter of posterior naris. Gill rakers 3+1+8‒9, densely denticulated on proximal side. Cleithrum and supracleithrum each with 5‒7 serrae.

First dorsal fin commencing slightly behind pelvic-fin, with 7 spines, third spine longest (III>IV>V>VI>II>VII>I). Second dorsal with one spine and 11 rays. Anal fin commencing beneath base of second-dorsal fin ray 3 or 4, with 3 spines, the third one longest (III>II>I) and 8 rays, the last one branched to base. Pectoral fin with 14 rays, 86.5‒89.6% length of pelvic fin, which has 1 spine and 5 rays. Length of pelvic-fin spine equal to or slightly shorter than dorsal spine V, longer than dorsal spine VI. Distal profiles of pectoral, pelvic, anal and second-dorsal fins rounded. Caudal fin rounded, with 6‒7+9+8+6‒7 rays. Caudal peduncle depth 71.2‒78.5% its length.

Scales, ctenoid; body and head scaled, except for snout, throat, preorbital and interorbital regions. Dorsal and anal fins reposed in a scaly sheath. Second dorsal, caudal, anal and lateral area of pelvic fin densely covered with minute scales. Lateral line with 56‒59 scales on body, commencing immediately posterior to supracleithrum, extending almost to tip of caudal fin; two rows of pored scales on caudal fin, one above and one below median lateral line. Seven scales in transverse line between base of third dorsal-fin spine and lateral line; 10 or 11 in transverse line between anus and lateral line; 24 circumpeduncular scales.

Coloration. In 70% alcohol ( Fig. 3 ), head and body olive-tan, darker above lateral line and dorsal region of head, lighter below, ventrally light yellowish-brown. Fins greenish-brown, interradial membrane of dorsal fin light greenish-brown, somewhat darker towards distal margin. Second dorsal fin, caudal and anal fins dark olive brown, pectoral and pelvic fins somewhat lighter.

Etymology. The species-name is a patronym honouring the Burmese patriot U Wisara; it is formed as a substantive in apposition. We suggest Myanmar Sea Bass as the common name of this species.

Remarks. Ward et al. (2008) investigated CO1 sequence divergence in Lates from Western Australia, Queensland, Singapore and Myanmar. While the former three populations were shown to be almost identical (0.5% divergence), the Myanmar specimens showed a divergence of 9.5%, sufficient to signify a distinct species ( Page & Hughes 2010; Benziger et al. 2011). The type series of L. uwisara comprises the same specimens analysed by Ward et al. (2008). Interestingly, these authors also found a sample of Lates from French Polynesia to be identical to three of the Myanmar specimens. Lates does not occur naturally in French Polynesia where it has, however, been introduced for aquaculture ( FAO 2011). While it is thus clear from Ward et al. (2008) that L. uwisara has already been used in aquaculture, it also raises a question over its type locality: is it indigenous to Myanmar waters, or might it have been introduced there, too? Data on three further Myanmarese specimens (ZSI FF 125, 177 mm SL, from Pegu [Bago]; ZSI FF 302, 141 mm SL, from Moulmein [Mawlamyaing]; and ZSI FF 410, 263 mm SL, from Akyab [Sittwe]) in the Francis Day collection at the ZSI (collected ca 1880), kindly provided by S. Batuwita (pers. comm.), indicate they are examples of L. uwisara , leading us tentatively to regard the species as being originally from Myanmar. If the species has indeed entered into widespread use in aquaculture, however, it is likely to be recorded from additional localities in the future.

The specimens in our series of L. uwisara are significantly larger (mean 350 ± s.d. 13 mm SL) than those in the other species ( L. calcarifer , 178 ± 45 mm SL; L. japonicus , 205 ± 39 mm SL; L. lakdiva , 238 ± 18 mm SL). It is possible, therefore, that at least one of the characters in the diagnosis of L. uwisara —viz., eye diameter less than depth of maxilla—is a consequence of allometry, which is particularly striking in the case of fish eyes ( Howland et al. 2004). The number of scale rows between the third dorsal spine and lateral line, however, remains constant within species across the sample examined and, together with the relative lengths of the pelvic, dorsal and anal fin spines, may provide the best means of identifying this species.

Figures

FIGURE 3. Lates uwisara, holotype, ANFC H. 6316 - 11, 332 mm SL.