Taxonomy & naming
Pogonoschistura pawaiensis was described in 2026 by Jörg Bohlen, Tomáš Dvořák and Vendula Šlechtová in the journal Fishes, alongside the formal erection of the new genus Pogonoschistura itself. The work followed directly from a 2024 molecular phylogeny (Šlechtová et al.) that split the family Nemacheilidae into six well-supported major clades — Northern, Eastern, Southern, Indochinese, Sundaic and Burmese — and showed that species long carried under the genus name 'Schistura' were scattered across three of those clades. Because the type species of Schistura, S. rupecula, belongs to the Southern Clade, every 'Schistura' species sitting in the other clades needed a new generic home. Within the Burmese Clade, the authors resolved one such orphaned lineage — 'Schistura' kohchangensis and an undescribed sister form — into the new genus Pogonoschistura, and formally named the undescribed species Pogonoschistura pawaiensis. A second orphaned Burmese-Clade lineage, 'Schistura' savona, was reassigned in the same paper to the older available name Acoura.
The genus name Pogonoschistura combines the Greek pogon ('beard'), referring to the very long barbels of both species in the genus, with Schistura, the nemacheilid genus name the species were long carried under. Its type species is Pogonoschistura kohchangensis (Smith, 1933), described from Koh Chang Island in eastern Thailand; P. pawaiensis, described from a waterfall far to the west on the Thai–Myanmar border, is its only known congener. The species epithet pawaiensis was given, in the authors' own words, 'for Pa Wai waterfall, the type locality.' Phylogenetic analysis placed Pogonoschistura as the sister lineage to Indoreonectes, a genus of stout-bodied, long-barbelled loaches from the Western Ghats and peninsular India — the two genera share a stout body shape, long barbels, closely spaced nostrils, a spotted head pigmentation pattern and variable body barring, though Pogonoschistura differs in caudal-fin shape, nasal-tube extent, lateral-line length, dorsal-fin position, pectoral-ray count and the presence of sexual dimorphism, which Indoreonectes lacks.
Morphology
Pogonoschistura pawaiensis is a moderately elongated nemacheilid loach. Body depth increases fairly steeply to about the mid-point between the snout and the dorsal-fin origin, then holds nearly steady back to the anal fin, decreases within the anal-fin base, and rises again slightly toward the caudal-fin base. The head is slightly depressed, the anterior half of the body only slightly compressed, and the posterior half strongly compressed. The snout is rounded, and the caudal peduncle is about 0.75–0.85 times as deep as it is long. A free axillary pelvic lobe, smaller than the pupil diameter, is present, and small adipose crests run along the dorsal and ventral midline near the caudal-fin base. The holotype, a male, reaches 2.69 in standard length — the largest known specimen; the full type series spans 1.27–2.69 in SL across 16 examined specimens.
The dorsal fin carries 4 simple plus 7½ branched rays with a slightly convex margin; the anal fin 3 simple plus 5½ branched rays. The caudal fin has 9+8 branched rays, slightly emarginate with rounded lobes — the '9+8' count, together with 7½ branched dorsal rays, is one of the two meristic characters separating this species from its only congener, P. kohchangensis (8+8 caudal rays, 8½ dorsal rays). The pelvic fin has 8 rays and does not reach the anus; the pectoral fin usually carries 12 rays, occasionally 13. The body is fully scaled except for the area between the pelvic fins. The lateral line is incomplete, running from at least the vertical through the pelvic-fin origin to at most the vertical through the anus, and bears 31–82 pores. The cephalic lateral-line system comprises 7 supraorbital pores, 4+10 infraorbital pores, 8 preoperculo-mandibular pores and 3 supratemporal pores.
The barbels are notably long, the character behind the genus name: the inner rostral barbel reaches the vertical through the eye's anterior margin, the outer rostral barbel exceeds the vertical through the eye's posterior margin, and the maxillary barbel exceeds two-thirds of the distance to the pectoral-fin origin. The mouth is roughly twice as wide as long; the upper lip carries a small median incision and more than 30 fine furrows along its length, the lower lip a well-marked median interruption and 5–6 furrows on each side, and neither lip is papillated.
Colour after preservation is dark yellow to light brown, lighter in small specimens and darker in large ones. The dorsal half of the head bears small, irregular dark brown spots about one-quarter to one-half the eye diameter — smaller than the equivalent head blotches in P. kohchangensis, a second diagnostic character. Smaller specimens show 10–15 dark brown body bars, split medially but mostly connected dorsally, with bar count increasing as fish grow. The caudal-fin base carries a black bar with a broad median interruption, leaving a small round-to-triangular dorsal blotch and a short thin ventral bar — this consistent, wide gap is the species' third diagnostic character, as P. kohchangensis usually has a complete or only narrowly interrupted caudal bar. The dorsal fin carries a black spot at the base of the last unbranched ray and another at the base of the second-to-fourth branched rays; the anal and pelvic fins are hyaline.
Habitat
Pogonoschistura pawaiensis is currently known only from its type locality, Pa Wai Waterfall, which drains via the Mae Lamao stream into the Moei River — part of the Salween River basin — in Amphoe Phop Phra, Tak Province, western Thailand, near the border with Myanmar (about 16°34′30″ N, 98°50′02″ E). This is a fast-flowing, cascading hillstream habitat typical of many nemacheilid type localities in the region, though no specific water-chemistry data have been published. Its only congener, P. kohchangensis, occurs far to the east on Koh Chang Island and in nearby Chanthaburi Province drainages that feed the Gulf of Thailand — a very different, lowland-to-coastal setting — underscoring that the two species occupy quite separate parts of Thailand despite their close relationship.
Feeding
No dietary study has been published for this species. As with other Nemacheilidae, it can be expected to be a benthic micropredator picking small invertebrates and insect larvae from the substrate of its fast-flowing waterfall habitat, but this is offered here as the general family pattern rather than a confirmed observation.
Mating
Only adult males of Pogonoschistura pawaiensis develop the genus's characteristic small suborbital flap, located just in front of the vertical through the eye's anterior margin, together with a slit running roughly halfway back toward the base of the outer rostral barbel. Males also show broadened last-unbranched and first two branched pectoral-fin rays covered, along with the skin between them, in small tubercles that stop short of the fin margin; single tubercles continue on branched rays 5–7 without forming a dense covering. Curiously, only 3 of the 16 examined specimens showed these male characters clearly, and even the holotype — the largest known individual at 2.69 in SL — shows a markedly less developed flap and slit than considerably smaller mature males of the sister species P. kohchangensis. The describers raise the open question of whether full sexual dimorphism in this species only appears at a larger body size than represented in the available material, or whether the sampled fish simply had not yet reached full maturity. No courtship or spawning behaviour has been directly observed.
Breeding
There is no breeding record for Pogonoschistura pawaiensis in the wild or in captivity. By family pattern, Nemacheilidae are typically egg-scatterers over gravel or among stones in flowing water with no parental care, but nothing specific to this species' reproduction has been documented; the original description is a taxonomic account, not a life-history study.
In the aquarium
Pogonoschistura pawaiensis has no history in the aquarium hobby and is not known to have entered trade. It is known from a small series of museum specimens collected from a single waterfall locality during a 2026 taxonomic revision. Given its apparently single-locality range, there is no basis for care recommendations beyond the general expectation of cool, fast-flowing, well-oxygenated hillstream water typical of its waterfall habitat; this is a species that belongs to specialist taxonomic and conservation interest rather than to the trade.
Conservation
Pogonoschistura pawaiensis has not been assessed on the IUCN Red List and is recorded here as Not Evaluated. It is currently known only from Pa Wai Waterfall in Tak Province, Thailand — a single-locality range that is an inherent vulnerability flag for any stream fish, though as with many recently described Southeast Asian nemacheilids, the true range may be under-surveyed rather than genuinely this narrow. There is no evidence of any collection pressure from the aquarium trade.