Laubuka indawgyiana, Khin & Chen, 2025

Htay, Khin Yadanar, Song, Xin-Yuan, Oo, Thaung Naing & Chen, Xiao-Yong, 2025, A review of genus Laubuka (Cypriniformes: Danionidae) in Myanmar with description of two new species, Zootaxa 5618 (2), pp. 221-248 : 225-236

Laubuka indawgyiana sp. nov. Khin & Chen

urn:lsid:zoobank.org:act:B04A82D9-2AD1-401B-8E54-E26F2BE75004

Laubuca (Laubuca) laubuca : Prashad & Mukerji, 1929: 208 ( Myanmar: Indawgyi Lake).

Laubuka fulvescens : Kottelat & Nyein Chan, 2017: 3 ( Myanmar: Indawgyi Lake).

Holotype: SEABRI 20192858 , 44.7 mm SL, Nant Taung Sal Stream (25°14'30.47"N, 96°19'41.27"E), tributary of Indawgyi Lake , Mohnyin Township, Kachin State, Myanmar, collected by Thinn Su Tin, Lamin Ko Ko, and Nay Htet Naing, 25 October 2019.

Paratypes (n=52): SEABRI 20192859 – 61, 46.3 – 47.8 mm SL, 3 ex., same as holotype. SEABRI 20192045 , SEABRI 20192053 – 4, 37.5 – 49.0 mm SL, 3 ex., Nant Yim Khar Stream (25°5'7.35"N, 96°16'53.91"E), tributary of Indawgyi Lake , collected by Thinn Su Tin and Nay Htet Naing, 16 February 2019 . SEABRI 20192382 , 30.1 mm SL, 1 ex., Nant Paung Sin Stream (25°7'38.11"N, 96°17'24.81"E), tributary of Indawgyi Lake , Mohnyin Township, Kachin State, Myanmar, collected by Thinn Su Tin and Lamin Ko Ko, 7 May 2019 . SEABRI 20230087 –8, 33.2– 41.3 mm SL, 2 ex., Lwal Moon Stream (25°15'39.22"N, 96°23'29.71"E), 27 January 2023 ; SEABRI 20230138 –40, 44.3–51.0 mm SL, 3 ex., Nam Pa De Stream (25°9'42.14"N, 96°17'12.28"E), 28 January 2023 ; SEABRI 20230260 – 61, 39.0– 43.1 mm SL, 2 ex., Nant Yim Khar Stream (25°5'7.35"N, 96°16'53.91"E), near Lon Ton Village , 29 January 2023 ; SEABRI 20230663 -675, 33.5–44.5 mm SL, 13 ex., margin of Indawgyi Lake (25°4'24.11"N, 96°17'34.19"E), 31 January 2023 ; SEABRI 20230778 , 42.1 mm SL, 1 ex., Kone Ma Na Stream (25°8'3.25"N, 96°16'25.64"E), 3 February 2023 ; SEABRI 20230952 –955, 36.5–54.5 mm SL, 4 ex., Yae Aye Stream (25°17'4.73"N, 96°23'31.33"E), 4 February 2023 ; SEABRI 20231670 –71, 39.0– 43.1 mm SL, 2 ex., upper Nant Yim Khar Stream (25°5'7.79"N, 96°16'36.78"E), 10 February 2023 ; SEABRI 20231815 –26, 31.1–39.5 mm SL, 12 ex., Nar La Tan stream (25°17'20.29"N, 96°24'21.82"E) near Chaung Wa Village, 14 February 2023 ; SEABRI 20231892 –7, 37.0– 54.5 mm SL, 6 ex., swamp pool (25°4'24.11"N, 96°17'34.19"E) near Indawgyi lake , 15 February 2023, tributaries of Indawgyi Lake , Mohnyin Township, Kachin State, Myanmar, collected by Nay Htet Naing , SEABRI 20244030 , 43.5mm SL, 1 ex., Mogaung Stream (25°18'34.28"N, 96°56'19.98"E), Mogaung Township, Kachin State, Myanmar, collected by local collector, 28 May 2024 .

Diagnosis

The new species can be distinguished by the combination of the following characters: Dorsal profile of head straight, absence of any markings except roundish humeral spot behind operculum, dorsal profile convex, more convex ventral profile, predorsal outline rising, the highest point at origin of dorsal-fin-base, caudal fin yellow, pectoral fin long with i, 7–8 rays, not reaching end of pelvic-fin rays, lateral line complete with 28–30 scales, predorsal scales 16–18.

Description

Measurement and counts are shown in Table 4 , and Figures 3 and 4 for general appearance. Body elongate, dorsal profile convex, slightly incurved between dorsal-fin origin and caudal-fin origin. Predorsal outline rising, leveling out to dorsal-fin-base, the highest point at origin of dorsal fin. Thorax and abdomen curved, without keel. Head small, dorsal profile almost straight. Eyes large and placed laterally, visible in both dorsal and ventral views, their diameter larger than snout length. Mouth superior. Lower jaw smooth, tubercles absent. Nostrils closer to orbit than to snout tip, dorsolaterally oriented. Barbels absent.

Scales cycloid, thin, and transparent. Dorsal-fin origin slightly posterior to anal-fin origin, length of rays gradually decreased from second unbranched ray. Dorsal-fin rays ii, 7½ (25), 8½ (29). Anal-fin base longer than dorsal-fin base, posterior rays gradually shorter. Anal-fin rays with iii, 17½ (18), 18½ (36). Pectoral fin falcate, not reaching end of pelvic fin. Pectoral-fin rays i, 7 (28) or 8 (26). Pelvic fin short, not reaching anus. Pelvic-fin rays with i, 4 (17) or 5 (37). Caudal peduncle short. Caudal fin forked, upper lobe slightly longer. Lateral line complete, with 28 – 30+1 scales. Predorsal scales 16 (17), 17 (13), 18 (24). Circumpeduncular scales 12 (54).

Coloration

Preserved specimens pale in ground color, dorsal outline darker, with a faded longitudinal line along midline of body, an apparent dark humeral spot behind operculum. Sides of body and fins with diffused melanophores. In life, body golden bronze, abdomen silver with a black edge in middle and a roundish humeral spot behind operculum. Pectoral and pelvic fins hyaline. Dorsal, anal, and caudal fins tinged yellow, outer margins with black ( Fig. 3A ).

Geographical distribution

Collections were made in streams with various habitat types ( Fig. 5 ) in Kachin State. Based on our field collections and historical records, Laubuka indawgyiana is distributed in Indawgyi Lake and its tributaries, including streams in Kachin State.

Habitat and biology

The type locality, Nant Taung Sal Stream, is a muddy stream with weeds on the surface. Both Yae Aye and Nant Yim Khar streams are sandy streams with shallow and clean water. Nant Paung Sin Stream, a prevention area of Indawgyi Lake, is a shallow lakeshore habitat with weeds and grass along its waterside. Nar La Tan Stream was also a muddy stream. Laubuka indawgyiana inhabits clear, shallow streams with sandy substrates and muddy habitats. Coexisting species include Pethia didi , Esomus danrica , Rasbora daniconius , and Paracanthocobitis linphya .

Etymology

The noun “Indawgyi” refers to Indawgyi Lake, the type locality of the species. The vernacular name is (Indawgyi Ngar Yin Baung Sar).

Comparisons

Laubuka indawgyiana is different from all other species in Myanmar by its unique body shape, convex dorsal outline, more convex ventral outline, and the absence of spot on caudal-fin base. In the phylogenetic trees, L. indawgyiana and L. tenella are grouped into the same clade. L. indawgyiana is distinguished from L. tenella , to which it has the closest relationship, by the absence of a posterior stripe and anterior series of vertical bars (vs. presence); 4–5 branched pelvic-fin rays (vs. 6); and pectoral-fin rays 7–8 (vs. 10–11).

Laubuka indawgyiana is differentiated from other congeners based on the following characters: the absence of any markings other than the humeral spot behind the operculum in alive specimens (vs. a mid-lateral stripe on body in L. fasciata , L. parafasciata , and L. trevori , a series of anterior vertical bars and posterior lateral stripe ending a triangular spot on caudal-fin base in L. siamensis , distinct vertical bars on the side of body anteriorly in L. lankensis , L. varuna , L. insularis , L. ruhuna , and L. caeruleostigma , both the humeral and caudal-peduncle spots in L. latens , mid-lateral line which is more apparent on posterior half of body in L. laubuca in India and Myanmar); 28–30+1 lateral-line scales (vs. 31–33+ 2 in L. siamensis , 31–33+ 1–2 in L. ruhuna , L. varuna , L. trevori , and L. latens , 34– 37+ 1–2 in L. lankensis and L. insularis , 33–35+ 1–2 in L. hema ); 16–18 predorsal scales (vs. 18–21 in L. insularis , L. lankensis , L. ruhuna , and L. hema ); and 7–8 branched pectoral-fin rays (vs. 9–10 in L. fasciata and L. myitthaensis , 11 in L. siamensis , 9–12 in L. parafasciata , 10–12 in L. hema , 11–12 in L. latens and L. varuna ).

Figures

FIGURE 3. Laubuka indawgyiana sp. nov., A. SEABRI 20190759, holotype, 44.7 mm in SL, shortly after capture, live specimen photo by Nay Htet Naing; B. holotype, in preservative; C. SEABRI 20192051, paratype, 39 mm in SL; D. SEABRI 20244030, 43.5 mm in SL; Mogaung Stream, Kachin State.

FIGURE 4. Coloration of Laubuka indawgyiana sp. nov. in aquarium, SEABRI 20244030, paratype, 43.5 mm in SL; Mogaung Stream, Kachin State, photo by Khin Yadanar Htay.

FIGURE 5. Habitats of Laubuka indawgyiana sp. nov. in the Indawgyi Lake Basin, A. Nant Yim Khar Stream, B. Nant Paung Sin Stream, C. Indawgyi Lake, photos by Ei Mon Kyaw.