The freshwater-fish genus Laubuka contains ∼13 species distributed through the lowlands of tropical South and South-east Asia. Four of these species (Laubuka lankensis, L. varuna, L. ruhuna, and L. insularis) are reported as endemic to Sri Lanka, a remarkable datum given the island’s small size. We sampled populations of Laubuka at 56 locations in 14 of the island’s principal river basins and analysed their morphological, meristic, phylogenetic, and phylogeographic relationships using the mitochondrial genes cytochrome b and cytochrome c oxidase subunit 1 and the nuclear recombination activating protein 1. We investigated the geographic structure, and delineated species using molecular species delimitation methods and morphological analysis within the general lineage concept of species. Molecular and morphological analyses failed to identify L. ruhuna and L. insularis as distinct species; we show them to be synonyms of L. varuna and L. lankensis, respectively. Taxonomic inflation in previous literature is attributed as a result of limited sampling and negligence of size allometry. Additionally, a third, cryptic species discovered in this study is described as L. hema sp. nov. which is evidently confined to the headwaters of the Gal basin in eastern Sri Lanka. Phylogenetic and haplotype network analyses suggest phylogeographic structure within both the southwest-endemic L. varuna and the dry-zone endemic L. lankensis, but the former shows strong phylogeographic structure between adjacent basins. The Sri Lankan species of Laubuka do not form a monophyletic group: they stem from two dispersal or vicariance events, one involving the lineage that led to L. varuna in south-western Sri Lanka, and the other, of [L. lankensis + L. hema] in the dry zone. http://zoobank.org/urn:lsid:zoobank.org:pub:D2A29329-E0E7-447E-B316-81049212CCCB http://zoobank.org/urn:lsid:zoobank.org:act:920E5DC0-CEDC-4243-98C7-12CCF829CBCD

Schistura scripta, new species, is described from Nakiyadeniya in the south-western lowlands of Sri Lanka. It can be distinguished from all other congeners from Sri Lankan and peninsular India by the combination of the following characters: an incomplete lateral line with 53–76 pores, ending beneath the dorsal-fin base or slightly beyond; 7–13 post-dorsal bars; 7½ branched dorsal-fin rays; absence of an axillary pelvic lobe; and absence of a suborbital flap.

The taxonomy of the three native taxa assigned to the genus Labeo (L. dussumieri, L. fisheri and L. porcellus lankae) in Sri Lanka is reviewed. The population hitherto identified as L. dussumieri in Sri Lanka is shown to be a distinct species, here named L. heladiva. Labeo heladiva, new species, has a wide distribution in the low and mid-elevations of the island and is distinguished from its Indian congeners by the combination of having two pairs of barbels; 12–13 branched dorsal-fin rays; lateral line with 44–51 scales; ½8–½9+1+6–7 scales in transverse series; and 19–22 circumpeduncular scales. It differs from its closest relative, L. dussumieri, principally by having 44–51 vs. 50–60 lateral-line scales, 19–22 vs. 22–27 circumpeduncular scales, and by uncorrected pairwise genetic distances of 1.27–2.22% and 1.88–2.91% for the two mitochondrial genes COI and cytb, respectively. Labeo fisheri, which is endemic to the upper reaches of the Mahaweli River basin in the Knuckles mountain range and the central hills in the vicinity of Kandy, is distinguished from Indian congeners by having (in combination) only a single pair of barbels; dorsal fin with 10–12 branched rays; lateral line with 37–39 scales; 7+1+4½–6 scales in transverse series; and 17–20 circumpeduncular scales. Labeo lankae is recognized as a valid species endemic to Sri Lanka. Long suspected to have become extinct, or known only from spurious records, an extant population is reported from the northern dry zone of the island. Labeo lankae is the sister species of L. porcellus of peninsular India; it can be distinguished from its congeners by having, in combination, 10–12 branched dorsal-fin rays; 36–39 lateral-line scales; ½8+1+5–6½ scales in transverse series; and 21–24 circumpeduncular scales. It differs from L. porcellus principally by having ½8 (vs. ½6–½7) scales between the origin of the dorsal fin and the lateral line, 21–24 (vs. 20–21) circumpeduncular scales and uncorrected pairwise genetic distances of 1.27% and 1.41% for the mitochondrial genes COI and cytb, respectively. The three species of Labeo in Sri Lanka do not form a monophyletic group.