Laubuka laubuca

Laubuka laubuca (Hamilton, 1822) Cyprinus (Chela) laubuca Hamilton, 1822: 342 (India: “ponds of the northern parts of Bengal”). Perilampus fulvescens Blyth, 1860: 163 (Myanmar: Tenasserim). Chela laubuca Menon, 1999: 36. Chela (Chela) laubuca Silas, 1958: 70 (Myanmar: Sitang River). Chela laubuca: Bănărescu, 1968: 54. Laubuka laubuca: (Kottelat, 2013): 119. Specimens examined (n=5): SEABRI 20160474 – 51, 5 ex., 27.5–50 mm SL, Tein Stream (22°12'12.27"N, 95°44'17.31"E) near Sadaung Village, Sagaing Region, Myanmar, collected by Xiao-Yong Chen, Tao Qin, Shu-Sen Shu, Khin Mar Myint, and Thinn Su Tin, 19 December 2016. Diagnosis Laubuka laubuca can be distinguished by the combination of the following characters: Head bending upward, presence of a black roundish humeral spot behind operculum and a fainted spot at origin of caudal fin, a narrow black stripe from middle of body side to caudal but not reaching caudal-fin base, abdomen silver with a black edge in middle, pectoral fin long with i, 10–12 rays; not reaching end of pelvic-fin rays; lateral line complete with 29–36 scales, predorsal scales 14–17. Description Measurement and counts are shown in Table 5 and Figure 7 for general appearance. Body elongate, compressed laterally. Dorsal profile moderately arising, thorax and abdomen curved. Head small, bending upward. Eyes large and placed laterally, visible in both dorsal and ventral views. Mouth superior. Lower jaw smooth, tubercles absent. Nostrils closer to orbit than to snout tip, dorsolaterally oriented. Barbels absent. * From Lalramliana et al. (2017). Scales cycloid, thin, and transparent. Dorsal-fin origin at anterior two-thirds of body length, inserted posterior to anal-fin origin, length of rays gradually decreased from second unbranched ray to last one. Dorsal-fin rays ii, 8½ (5). Anal-fin base longer than dorsal-fin base, posterior rays gradually shorter. Anal-fin rays iii, 14½ (1), 17½ (1), 18½ (2), 20½ (1). Pectoral fin long, falcate, not reaching end of pelvic-fin rays. Pectoral-fin rays i, 10 (2), 11 (1), 12 (2). Pelvic fin short, not reaching anus. Pelvic-fin rays with i, 6 (4) or 7 (1). Caudal peduncle short. Caudal fin forked, upper lobe slightly larger. Lateral line complete, with 29–36+1 scales. Predorsal scales 14 (1), 15 (3), 17(1). Circumpeduncular scales 12 (5). Coloration Preserved specimen yellowish, dorsal contour darker, with a dark humeral spot. A thin black line present from middle of body side to caudal but not reaching caudal-fin origin. Sides of body and fins with diffused melanophores. Live specimens with pale golden-brown reflections, abdomen silver with a black edge in middle, a bright copper green midlateral line which is more apparent on posterior half of body and caudal peduncle, and the black humeral and caudal-peduncle spots (Fig. 7A). Distribution Laubuka laubuca was recorded from Tenasserim in Myanmar by Blyth (1860) as Perilampus fulvescens. The specimens examined in this study are found in the Tein Stream, Ayeyarwady drainage, near Sadaung Village, Sagaing Region in Myanmar. It was also recorded in Mawlamyine, the Sittaung River, Mandalay, and east of Rakhine Yoma in Myanmar (Silas 1958; Kullander et al. 2018). Prashad & Mukerji (1929) and Kottelat (2017) reported it from Indawgyi Lake. By comparing all specimens recently collected during five surveys in this lake from 2018 to 2023, it is confirmed that there is no Laubuka laubuca in Indawgyi Lake, and the records of Prashad & Mukerji and Kottelat match the features of L. indawgyiana sp. nov. (Fig. 2). Habitat and biology This species usually inhabits shallow streams with slow and moderate flow water and seasonal wetlands. Coexisting species include Mystus pulcher, Channa striata, Channa gachua, Lepidocephalichthys berdmorei, Systomus sarana, Osteobrama belangeri, Esomus danrica, Danio albolineatus, and Mastacembelus armatus. Comparisons The color pattern, measurements, and counts do not include characters separating from L. laubuca reported here from Bangladesh and India (Kullander et al. 2018; Sudasinghe et al. 2020). Laubuka laubuca is distinguished from Sri Lanka Laubuka species by having 14–17 predorsal scales (vs. 18–21 in L. lankensis, L. insularis, L. ruhuna, and L. hema); 6–7 branched pelvic-fin rays (vs. 5); and the absence of distinct vertical bars on the lateral body anteriorly (vs. presence) in L. lankensis, L. insularis, L. varuna, and L. ruhuna. It is further distinguished from Indian Laubuka species by possessing 14–17 predorsal scales (vs. 16–18 in L. parafasciata, L. fasciata, L. trevori, and 18–21 in L. latens); 6–7 branched pelvic-fin rays (vs. 5 in L. trevori and L. latens); and the presence of bright copper midlateral line which is more apparent on posterior half of body in alive specimens (vs. a broad midlateral stipe on the body in L. parafasciata, L. fasciata, and L. trevori, the absence of any markings on the side of body other than the humeral and caudal-peduncle spots in L. latens). It is distinguished from Southeast Asian species by the absence of short vertical bars on the anterior side (vs. presence in L. caeruleostigmata, L. siamensis, and L. tenella); and additionally, from L. siamensis by possessing 6–7 branched pelvic-fin rays (vs. 5) and 14–17 predorsal scales (vs. 20). Remarks All the characters of Laubuka laubuca considered here overlap with those of L. fulvescens, with the exception of a black margin on the caudal fin. The published photograph of Chela laubuca (Silas 1958; fig. 3) suggests that it is in a poor state of preservation and the specimen is imperfectly characterized. Menon (1999) treated Perilampus fulvescens as a synonym of Chela laubuka, which was followed by Kottelat (2013). We follow these works and treat L. fulvescens as a synonym of L. laubuca.