Loaches · Stone & brook loaches

Magnischistura khaokrajom

Page, Pawangkhanant & Cagle, 2026

IUCNNOT EVALUATED
NEnot on the EX–LC scale
CARESNOT LISTED
Depthnot recorded
DietNot documented for this species; family pattern is a benthic micropredator taking small invertebrates and insect larvae off gravel and stone
BreedingNot documented; inferred family pattern is an egg-scatterer over gravel/among stones in flowing water, with no parental care
Sexual dimorphismYesA tubercle-tipped suborbital flap is present in both sexes (unusual among related genera, where it is normally male-only); mature males additionally carry a highly modified, tubercle-covered pectoral fin not present in females
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Magnischistura khaokrajom is a small nemacheilid loach described in 2026 as the sole member of a new genus, from a single tributary stream of the Pachi River in the Tenasserim Hills of western Thailand, near the Myanmar border. It was singled out for its own genus on the strength of an unusual character: a suborbital flap present in females as well as males, a combination not shared by the several other recently described loach genera that carry a similar-looking flap. Mature males additionally carry a highly modified, tubercle-covered pectoral fin, which the describing authors suspect helps a male align himself against a female during spawning. Genetic data show the genus is not closely related to any of the other flap-bearing nemacheilids it superficially resembles, making the similarity a case of convergent evolution rather than shared ancestry.

What's in the name

Magnischistura khaokrajommag-nih-shis-TUR-ah kow-krah-JOM

Magnischistura
  • magnusLatinlarge, great — the likely first element, following the naming convention of related genera built on 'Schistura'
  • Schisturagenus namea related nemacheilid genus name, used as the second element as in several sibling genera (Kayahschistura, Pogonoschistura, Rhyacoschistura)
khaokrajom
  • khaoThaimountain, hill
  • krajomplace nameapparently part of a local Thai place name near the Suan Phueng type area; the precise landmark could not be confirmed from the abstract-level source material available for this article

Taxonomy & naming

Magnischistura khaokrajom was described in 2026 by Lawrence Page, Parinya Pawangkhanant, Weerapongse Tangjitjaroen, David Cagle, Basil Williams and Zachary Randall in Zootaxa, as the type and only species of the new genus Magnischistura. It belongs to the family Nemacheilidae, the stone and brook loaches — the largest loach family by far, comprising hundreds of small, often narrow-range species distributed from the Middle East to East Asia. The Catalog of Fishes (Eschmeyer, CAS) credits the species account itself to Page, Pawangkhanant and Cagle, three of the paper's six co-authors, following standard nomenclatural practice for multi-author descriptions.

The abstract of the description explains that Magnischistura shares a globulous, tubercle-tipped suborbital flap and a highly modified male pectoral fin with several other recently described nemacheilid genera, but that molecular data failed to support a close relationship to any of them — the resemblance is convergent, not a sign of shared ancestry. What sets Magnischistura apart morphologically is that the suborbital flap is present in females too, not restricted to males as in its lookalikes. The genus name most plausibly combines the Latin magnus ("large, great") with Schistura, a related nemacheilid genus name — the same naming convention used for several sibling genera such as Kayahschistura and Pogonoschistura — though the paper's own dedicated etymology section was not available in the source material captured for this article, so this derivation is offered as the standard convention rather than a direct quotation. The species epithet khaokrajom appears to reference a Thai place name local to the Suan Phueng type area (khao means "mountain" in Thai), but the exact landmark it denotes could not be confirmed from the material available.

Morphology

The description's abstract documents only the genus- and species-diagnostic characters, not a full morphometric account: a globulous suborbital flap bearing tubercles at its extremity, present in both sexes — an unusual state, since the comparable flap in related nemacheilid genera is typically restricted to males — and, in mature males only, a highly modified pectoral fin. No standard length, fin-ray counts, or colour pattern were captured in the source material available for this article; the full description text sits behind a journal paywall.

Habitat

The type locality is Huay Thong An, a small tributary stream of the Pachi River within the larger Mae Klong River basin, in Suan Phueng District, Ratchaburi Province, western Thailand (13.54732° N, 99.20394° E), at an elevation of about 2133 ft in the Tenasserim Hills along the Thai–Myanmar border. This places the species in a highland tributary setting typical of many recently described Southeast Asian nemacheilids, but no further water-chemistry or habitat detail is given in the source material available.

Feeding

No dietary study has been published for this species. Nemacheilid loaches as a family are bottom-foraging micropredators, working over gravel and stony substrate for small invertebrates and insect larvae; this is stated here only as the general family pattern, not a confirmed observation of Magnischistura khaokrajom.

Mating

The description's authors put forward a specific functional hypothesis for the male's modified pectoral fin: that its tubercle-covered, thickened rays help a male position himself against a female during spawning. Beyond this hypothesis, no courtship or spawning behaviour has been directly observed for the species. The presence of a suborbital flap in females as well as males is diagnostic for the genus, but its function — whether it plays any role in courtship or is unrelated to reproduction — is not addressed in the material available.

Breeding

There is no breeding record for Magnischistura khaokrajom, 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 this has not been documented for this species specifically and is offered here only as the general expectation for the family.

In the aquarium

Magnischistura khaokrajom has no history in the aquarium hobby. It is known from a small series of museum specimens collected from a single tributary stream in a 2026 taxonomic survey, and there is no evidence of it having entered trade. Given its apparently narrow known range and total absence from commerce, there is no basis for care recommendations beyond noting the cool, flowing, well-oxygenated highland stream conditions of its type locality.

Conservation

Magnischistura khaokrajom has not been assessed on the IUCN Red List and is recorded here as Not Evaluated. It is known only from its type locality, a single small tributary of the Pachi River in the Tenasserim Hills of western Thailand — as with many recently described stream fishes, the true range may simply be unsurveyed rather than genuinely this narrow, but no other population has been documented. There is no evidence of any collection pressure from the aquarium trade.

Sources

  1. Eschmeyer's Catalog of Fishes (CAS) — Magnischistura khaokrajom Page, Pawangkhanant & Cagle, 2026
  2. Page, L.M., Pawangkhanant, P., Tangjitjaroen, W., Cagle, D.K., Williams, B.R. & Randall, Z.S. (2026) Magnischistura khaokrajom, a new genus and species of loach (Cypriniformes: Nemacheilidae) from the Pachi River drainage in western Thailand. Zootaxa 5757 (no. 6): 583–599.

Last reviewed 2026-09-03.

How to cite

Aquarist Atlas (2026). Magnischistura khaokrajom. Aquarist Atlas.https://www.aquaristatlas.com/loaches/magnischistura-khaokrajom/

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