Taxonomy & naming
Glossolepis pseudoincisa was described by Gerald R. Allen and Norbert J. Cross in 1980, as part of their broader revisionary work on the rainbowfishes of New Guinea. Eschmeyer's Catalog of Fishes — the governing authority for valid names — records the species as valid under the combination Glossolepis pseudoincisa Allen & Cross, 1980, placed in the genus Glossolepis where it was originally described, so no parenthetical authority applies. The genus Glossolepis is one of the New Guinea rainbowfish lineages within the family Melanotaeniidae, the true rainbowfishes of the order Atheriniformes.
The specific epithet pseudoincisa translates as 'false incisa' — resembling but not identical to Glossolepis incisa, the red rainbowfish of Lake Sentani. The name flags the new species as a close look-alike of an already-known congener. Glossolepis itself derives from the Greek glossa, 'tongue', and lepis, 'scale'.
The original description was based on type material from an oxbow lake beside the Tami River, about 14 mi southeast of Jayapura, with the holotype held at the Rijksmuseum van Natuurlijke Historie (RMNH 28072). The species has since been recorded more widely across the Tami River floodplain and from small lakes near the southern shore of Lake Sentani, and Allen and Kadarusman reported it as common at the type locality in 2015. Catalog of Fishes notes that the name has appeared in two grammatical forms — the original Glossolepis pseudoincisus and the variant Glossolepis pseudoincisa — and currently treats Glossolepis pseudoincisa Allen & Cross 1980 as the valid combination.
Morphology
Glossolepis pseudoincisa is a small rainbowfish, reaching a maximum recorded length of about 3 in standard length (the figure given in the literature is from male or unsexed material). The body is fusiform — the relatively elongate, normal rainbowfish shape rather than the very deep, diamond-bodied form seen in some larger Melanotaenia — and laterally compressed in the manner typical of the family.
The recorded meristic counts: dorsal-fin spines 6 to 7, dorsal soft rays 10 to 12, a single anal spine, and anal soft rays 18 to 22. As in other Melanotaeniidae, the dorsal fin is divided into a short anterior and a longer posterior portion. These counts overlap broadly with those of related rainbowfishes — fitting for a species split from its near-twin Glossolepis incisa on fine differences rather than any single dramatic character.
Live coloration is not reliably documented. The species is known essentially from preserved specimens and an old collection, so no confident account of the adult male's breeding colours, the female's appearance, or how the two differ in life can be given here. The colour data are sparse, and this article does not attempt to reconstruct them.
Habitat
The type locality is an oxbow lake beside the Tami River, roughly 14 mi southeast of Jayapura, in the far northeast of Indonesian Papua Province (formerly Irian Jaya), New Guinea, at about 2°42'S, 140°55'E. Beyond the Tami River floodplain itself, the species is also known from small lakes perched at about 361 ft elevation near the southern shore of Lake Sentani — including Lake Ifaten (Emfote) and Lakes Iwom and Yaniruk — a short distance northwest of the Tami River.
An oxbow lake is a cut-off meander loop — a still or very slow-flowing backwater, typically warm, vegetated, and seasonally variable. The species lives in these floodplain oxbows and small perched lakes, gathering in dense aquatic vegetation, a freshwater fish of tropical lowland waters. The physical and chemical conditions of these waters — temperature, pH, hardness, depth, clarity — went unrecorded in the available sources, so the habitat parameters are data sparse.
What shapes its conservation status is the narrow range: an estimated extent of occurrence of about 1,250 km2 across roughly seven locations, all subject to habitat change.
Feeding
No diet has been recorded for Glossolepis pseudoincisa in the available sources; FishBase lists no documented feeding biology for the species, and its estimated trophic level (about 2.9) is a model-derived figure rather than an observed one. Direct dietary data are therefore sparse.
What can be said comes from the family. Rainbowfishes of the Melanotaeniidae are typically opportunistic omnivores feeding in the upper and middle water column, taking small aquatic and terrestrial invertebrates — insect larvae, small crustaceans, surface-fallen insects — alongside algae and plant material. A small oxbow-lake rainbowfish would, on general grounds, be expected to follow that pattern.
This is offered only as family-level context, not as a documented account of this species. No stomach-content study, feeding observation, or captive feeding record for Glossolepis pseudoincisa was found in the sources.
Mating
Nothing is on record about the courtship or mating behaviour of Glossolepis pseudoincisa. So far as the available sources show, it has not been observed spawning in the wild or in captivity, and no description of male display, pairing, or breeding coloration exists. This section is data sparse.
By family analogy only: rainbowfishes are generally egg-scattering, plant-spawning fishes in which displaying males court females over fine vegetation, often most actively in the early morning, with no pair bond and no parental care. Whether Glossolepis pseudoincisa fits that pattern is unknown.
Nothing specific to this species' reproductive behaviour should be inferred from the above; it is included only to place the species within its family and to be explicit that no direct observations are available.
Breeding
No breeding account exists for Glossolepis pseudoincisa. The species is not known to have been bred, and there is no record of egg number, egg type, incubation time, fry development, or any other reproductive detail for it in the sources consulted. This information is genuinely absent rather than merely summarised, and it is reported here as data sparse.
FishBase's resilience estimate for the species — medium resilience, with an estimated population-doubling time of 1.4 to 4.4 years — is a modelled value used in stock and risk assessment, not an observation of breeding output, and should not be read as a measured fecundity.
The species reaches the hobby through captive-bred stock, yet no detailed published breeding protocol specific to it could be located for this atlas, and the particulars of its reproduction remain poorly documented.
In the aquarium
Glossolepis pseudoincisa does reach the aquarium hobby, but it is uncommon and specialist. According to the IUCN assessment, the fish in the trade are captive-bred rather than wild-caught, and it is not a fixture of the general ornamental market; no detailed, species-specific care or husbandry account could be located for this atlas.
For general orientation — not care advice validated for this species — congeners and other New Guinea rainbowfishes are usually kept in warm water (broadly the mid-20s Celsius), in soft to moderately hard, neutral-to-alkaline conditions, as active, peaceful schooling fishes that show best in groups. Those are family-level generalisations.
This remains a little-kept rainbowfish, and the honest position for an atlas is that detailed husbandry data specific to Glossolepis pseudoincisa are sparse.
Conservation
Glossolepis pseudoincisa is assessed as Vulnerable (VU) on the IUCN Red List under criterion B1ab(iii), with the assessment last assessed on 5 December 2019 (published 2020; assessors G.R. Allen & Kadarusman). The Vulnerable listing reflects a small, fragmented geographic range — an estimated extent of occurrence of about 1,250 km2 across roughly seven locations in the Tami River floodplain and small lakes near the southern shore of Lake Sentani — combined with a continuing decline in the quality of that habitat. Under the B1 criterion, a small extent of occurrence in few locations, together with ongoing habitat decline, is sufficient to trigger a threatened category.
The documented threats are settlement and housing development, oil-palm plantations, and invasive non-native species. Despite that pressure the population trend was assessed as stable, and the species was reported common at the type locality in 2015. It carries no harvest pressure of consequence — what trade exists is supplied by captive-bred stock — so the risk is habitat- and range-based rather than from exploitation.
The recommended priority is research into the species' population size, distribution, and trends; no conservation actions are specifically in place for it. Continued monitoring of the Tami River and Lake Sentani-fringe lakes would be the necessary basis for any future management.