Paralaubuca barroni Fowler, 1934

Tangjitjaroen, Weerapongse, Randall, Zachary S., Yang, Lei, Grudpan, Chaiwut & Page, Lawrence M., 2025, Taxonomic revision of Paralaubuca (Cypriniformes, Xenocyprididae), a taxon seemingly in decline, Zootaxa 5647 (4), pp. 301-330 : 319-322

Paralaubuca barroni Fowler, 1934

( Figures 1 , 5 , 9 )

Chela barroni Fowler, 1934:109 , fig. 61. Type locality: Thailand: Chiang Rai Province: Mekong River at Chieng Sen. Holotype: ANSP 57455 .

Chela barroni was described along with C. stigmabrachium from the Mekong River at Chiang Sen in northern Thailand by Fowler (1934), based on a single specimen ( Figure 9 ) measuring 104 mm TL and having 43 lateral-line scales, 7 branched dorsal-fin rays, 28 branched anal-fin rays, 9 pelvic-fin rays, 14 pectoral-fin rays, and 22 gill rakers. The illustration accompanying the description shows the pectoral-fin flap characteristic of Paralaubuca .

Bănărescu (1971) reported the holotype of C. barroni (now badly desiccated, Figure 9 ) to be 84.7 mm SL and possessing 24 gill rakers (abbreviated as “Sp. br.”) and 28 branched anal-fin rays. Bănărescu (1971) also gave counts of 53–55 lateral-line scales and 19–24 gill rakers for specimens of P. barroni from the Mekong River basin in Yunnan, China, as first reported in Wu et al. (1964), and noted that the count of 43 lateral-line scales given by Fowler for the holotype was an error. Bănărescu (1971) concluded that P. barroni differed from other species in the genus by having fewer scales and gill rakers. We found the holotype to be 77.1 mm SL.

Diagnosis. Paralaubuca barroni is most similar to P. typus but is distinguished by having 22–29 vs. 31–51 rakers on first gill arch, average of 54.8 vs. 58.4 lateral-line scales, and reaching much smaller size, 115.0 vs. 152.5 mm SL. Paralaubuca barroni is distinguished from P. harmandi by having 51–58 vs. 70–87 lateral-line scales, usually 25–27 vs. usually 22–24 branched anal–fin rays, usually 22 or 24 vs. usually 28–32 scales around caudal peduncle, and 38–41 (average=39.9, n=9) vs. 41–42 (usually 42, average=41.9, n=9) total vertebrae. Paralaubuca barroni has longer anal fin and anal-fin base, shorter preanal-fin length, and larger eye ( Table 9) than P. harmandi . Paralaubuca barroni is further distinguished from P. harmandi osteologically as described above and as shown in Figure 5 . Paralaubuca barroni , reaching 115.0 mm SL (Wu, et al. 1964), is much smaller than P. harmandi , which reaches 265 mm SL.

Description. See description of genus.

Distribution. Paralaubuca barroni is rare in institutional collections and is known from only three localities ( Figure 8A ). It was described from the Mekong River at Chieng Sen (Chiang Sen) in Chiang Rai Province in northern Thailand, subsequently recorded by Wu (1964) in Yunnan Province, China and thereafter from the Mekong River in Ubon Ratchathani Province, Thailand. Although we have not examined specimens from China, it has been reported from the lower reaches of the Lancang River by Wu et al. (1964), Zhang & Zhao (2016), and Tian et al. (2022). Tian et al. (2022) provided a photograph of a specimen of P. barroni . Collections in Ubon Ratchathani Province were made as recently as 2005.

In a field guide to fishes of Cambodia, So et al. (2019) included P. typus and P. barroni . However, the species were separated based on a continuous vs. discontinuous lateral line, which does not distinguish P. typus and P. barroni . No published record or specimen documents P. barroni in the Mekong basin as far south as Cambodia.

Like other species of Paralaubuca , P. barroni presumably occurs in flowing water in moderate to large rivers. The large distances between collections of P. barroni suggest it was previously much more widespread in the Mekong River basin than it is today, or because it lives in large difficult-to-collect rivers and is poorly represented in institutional collections. The former seems more likely, given the high frequency of P. typus in collections from the Mekong River.

Figures

FIGURE 1. Paralaubuca typus, (A) live, UF 248615, 95.6 mm SL, Ping River, Kamphaeng Phet Province, Thailand, 8 Feb 2022. (B) preserved, UF 193797, female, 123.6 mm SL, and (C) preserved male, 116.1 mm SL, Ping River, Kamphaeng Phet Province, Thailand, 10 Feb 2024. Paralaubuca barroni, (D) preserved, UF 249886, 72.9 mm SL, Mekong River, Ubon Ratchathani Province, Thailand, 16 Jul 2005. Paralaubuca harmandi, (E) live, UF 248526, 126.1 mm SL, Chao Phraya River, Ayutthaya Province, Thailand, 21 Jun 2022.

FIGURE 5. Lateral skull computed tomography (CT) scans of (A) Paralaubuca typus, UF 170312, 84.9 mm SL, Mun River, Ubon Ratchathani Province, Thailand, 16 Nov 2007, (B) P. barroni, ANSP 179934, 54.2 mm SL, Ubon Ratchathani Province, Thailand, 10 Feb 2021, and (C) P. harmandi, UMMZ 195277, 128.2 mm SL, Ratchaburi Province, Thailand, 14 Nov 1964. Dentary in blue, premaxilla in green, maxilla in pink, orbitosphenoid in yellow, parasphenoid in grey, entopterygoid in orange, supraneural 5 in red, exoccipital and supraoccipital in purple. Asterisk indicates suspensorium window of Gosline (1975).

FIGURE 8. Distributions of species of Paralaubuca. (A) Paralaubuca barroni. ★ type locality of Chela barroni, locality for P. barroni in China is an approximation. (B) Paralaubuca harmandi. · type locality of Culter siamensis, ▲ type locality of Culter wolfi, locality for P. harmandi in Cambodia is an approximation. Type localities of P. harmandi (Chao Phraya River) and Pseudolaubuca lateralis (Cochinchine) are ambiguous and not plotted. (C) Paralaubuca typus. ★ type localities of P. typus and Culter riveroi, ◆ type locality of Chela stigmabrachium.

FIGURE 9. Chela barroni holotype, ANSP 57455, 77.1 mm SL, Mekong River at Chiang Sen, Chiang Rai Province, Thailand. Photograph by Kyle R. Luckenbill.