Laubuka myitthaensis, Khin & Chen, 2025

Laubuka myitthaensis sp. nov. Khin & Chen

urn:lsid:zoobank.org:act:C34056E5-B906-4287-ACE5-7768F76449D2

Holotype: SEABRI 20181001 , 35.8 mm SL, Myittha River (23°13'52.86"N, 94°10'48. 54"E), near Yenatha Village, Kalaywa Township, Sagaing Region, Myanmar, collected by Nay Htet Naing and Paing Zaw, 22 March 2018. GoogleMaps

Paratypes (n=2): SEABRI 20193215 –6, 37.5–39.0 mm SL, 2 ex., Kalay market , fish from Myittha River , Sagaing Region, Myanmar, collected by Xiao-Yong Chen, Khin Yadanar Htay, and Nay Htet Naing, 7 November 2019 .

Diagnosis

The new species can be distinguished by the combination of the following characters: Absence of any markings on side of body other than the humeral spot behind pectoral fin, abdomen silver, dorsal-fin-base length less than half of anal-fin-base length, caudal-fin yellow, pectoral fin long with i, 9–10 rays; not reaching end of pelvic-fin rays; lateral line complete with 28–30+1–2 scales; predorsal scales 16–18.

Description

Measurement and counts are shown in Table 4 View TABLE 4 and Figure 6 View FIGURE 6 for general appearance. Body elongate, dorsal profile slightly curved, ventral profile strongly convex compared to dorsal profile. Thorax and abdomen curved. Head small and bending upward. Eyes large and placed laterally, well visible in both dorsal and ventral views. Mouth superior. Lower jaw smooth, tubercles absent. Nostrils closer to orbit than to snout tip. Barbels absent.

Scales cycloid, thin, and transparent. Dorsal-fin inserted slightly posterior to anal-fin origin, length of rays gradually decreased, very short dorsal-fin-base, less than half of anal-fin-base. Dorsal-fin rays ii, 8½ (2) or 9½ (1) rays. Anal-fin base long, posterior rays gradually shorter. Anal-fin rays ii, 17½ (2) or 19½ (1). Pectoral fin long, falcate, not reaching end of pelvic-fin rays. Pectoral-fin rays i, 9 (2) or 10 (1) rays. Pelvic fin short, small and falcate, not reaching anus. Pelvic-fin rays i, 6 (3). Caudal peduncle short. Caudal-fin deeply forked; its lower lobe slightly larger. Lateral line complete, with 28–30+1–2 scales. Predorsal scales 16 (2) or 18 (1). Circumpeduncular scales 12 (3).

Coloration

Preserved specimen brown, with a thin and indistinct black line above lateral line, extending to caudal peduncle, and fainted on anterior portion of body. An indistinct black humeral spot behind operculum and above pectoral fin. Sides of body and fins with diffused melanophores. Live specimens yellow, with silvery reflection, abdomen sliver. Pectoral and pelvic fins hyaline. Dorsal, anal, and caudal fins yellow, outer margins black ( Fig. 6A View FIGURE 6 ).

Geographical distribution

Laubuka myitthaensis is presently found in the Myittha River, Chindwin drainage, near Yenatha Village, Kalaywa Township, Sagaing Region, Myanmar ( Fig. 2 View FIGURE 2 ).

Habitat and biology

The species is found in deep water with steady flow and the benthic microhabitat is sandy with rocky ground. Coexisting species include Badis sp. , Homalopteroides sp. , Lepidocephalichthys goalparensis , Garra sp. , Hypsibarbus oatesii , Neolissochilus sp. , Pethia thelys , Raiamas guttatus , Esomus danrica , Rasbroa daniconius , and Paracanthocobitis linypha .

Etymology

The noun “Myittha” refers to the Myittha River, which is the type locality of this species. The vernacular name of Laubuka myitthaensis sp. nov. is (Myittha Ngar Yin Baung Sar).

Comparisons

Laubuka myitthaensis is distinguished from Laubuka siamensis , to which it has the closest relationship, by the absence of series of anterior vertical bars and posterior mid lateral stripe in alive specimens (vs. presence); 28– 30+1 lateral-line scales (vs. 31–33+2); and 16–18 predorsal scales (vs. 20). The coloration of both L. myitthaensis and L. indawgyiana resembles each other by the absence of any markings other than the humeral spot. Laubuka myitthaensis is distinguished from L. indawgyiana by possessing 9–10 branched pectoral-fin rays (vs. 7–8); and 6 pelvic-fin rays (vs. 4–5). It is distinguished from L. tenella by the absence of a dark stripe along the posterior third of the side, anteriorly replaced by a series of short vertical bars (vs. presence). It is distinguished from L. varuna by the absence of short vertical bars on the anterior side (vs. presence); 28–30+1–2 lateral-line scales (vs. 31–33+1–2); and 9–10 branched pectoral-fin rays (vs. 11). It is distinguished from L. laubuca by a shorter dorsal-fin-base length (11.8–13.4% SL, vs. 17.3–18.4% SL); indistinct humeral spot (vs. distinct); and absence of a midlateral line (vs. presence). It is further distinguished from L. fasciata by the absence of a mid-dorsal stripe along the side (vs. presence), a shorter pelvic-fin length (14.7–17.0% SL, vs. 31.2–35.3% SL); 28–30+1–2 lateral-line scales (vs. 32–33+1); 17½–19½ branched anal-fin rays (vs. 14½–15½); 6 pelvic-fin rays (vs. 5); and 8½–9½ branched dorsal-fin rays (vs. 7½). It is distinguished from L. lankensis by the absence of dark brown blotches on side of body, coalesced into a stripe on caudal peduncle (vs. presence), a shorter pelvic-fin length (14.7–17.0% SL, vs. 26.0–28.5 % SL), 28–30+1–2 lateral-line scales (vs. 34–37+1–2); and 16–18 predorsal scales (vs. 18–21). It is further distinguished from L. hema by dorsal, anal, and caudal fins yellow in live specimens (vs. fins tinged orange, with scattered melanophores); indistinct humeral spot (vs. distinct); 28–30+1–2 lateral-line scales (vs. 33–35+1–2); and 16–18 predorsal scales (vs. 18–21). Laubuka myitthanensis is differentiated from L. trevori and L. latens by the absence of any markings other than the humeral spot (vs. the broad dark-brown stripe along the side in L. trevori and both the humeral and caudal-peduncle spots in L. latens ; 28–30+1–2 lateral line scales (vs. 31–32+ 1–2 in L. trevori and 32–33+ 1–2 in L. latens ); and 6 branched pelvic-fin rays (vs. 5 in both L. trevori and L. latens ). It is distinguished from L. parafasciata by the absence of the broad dark-brown stripe along the side (vs. presence). It is further distinguished from L. caeruleostigmata by the absence of a series of short vertical bars on the anterior side (vs. presence) and 8½ branched pectoral-fin rays (vs. 11½–12½).