Taxonomy & naming
Pseudotropheus sp. "Lucerna Fin Spot" is an informal, undescribed taxon: it has no describing author, no publication date, and no entry in Eschmeyer's Catalog of Fishes. The trade name follows the usual pattern for undescribed mbuna — genus, "sp." to mark it as unnamed, then a descriptive tag combining a shared complex label with a locality or colour qualifier. "Lucerna" is used in the aquarium trade and field literature as a name element for a small number of related Pseudotropheus-group forms, including populations separately documented in this atlas as "Lucerna Blue Mozambique" and "Lucerna Blue Tanzania"; its precise origin and the exact relationship between these populations are not well documented in the sources available to us, and this article does not assert a confirmed identification beyond noting the shared trade convention. A formally described Pseudotropheus lucerna also exists in this atlas's records, but no confirmed link between that species and this trade complex is established here. "Fin Spot" identifies a marked spot reported on one of this population's fins as its distinguishing field character; which fin, and how many spots, has not been documented in detail in the sources available to us. Membe Point, the recorded locality, sits on the northeastern corner of Likoma Island, within the same stretch of rocky shore — running from Yofu Bay to Membe Point — documented as the range of the Critically Endangered Pseudotropheus cyaneorhabdos, though no relationship between the two is asserted here beyond shared geography.
Morphology
This form follows the standard Pseudotropheus body plan: a moderately elongate, laterally compressed body with the robust, specialised dentition — an outer row of bicuspid or unicuspid teeth over inner rows of tricuspid teeth — used across the genus to graze algae from rock surfaces. Its trade name identifies a marked spot on one fin as the diagnostic field character; ground body colour and full pattern details have not been documented for this population beyond that. Size is not separately documented for this form and is presumed to sit within the genus-typical Pseudotropheus range of roughly 3–4.5 in.
Habitat
Pseudotropheus sp. "Lucerna Fin Spot" is recorded from Membe Point, on the rocky northeastern corner of Likoma Island — a stretch of shore known in the wider literature for a dense and partly micro-endemic mbuna community, including the range of Pseudotropheus cyaneorhabdos. Like other Pseudotropheus, it is expected to hold territory among boulders and crevices in the shallow-to-intermediate rocky zone. Depths in this stretch of the Likoma shore run roughly 10–59 ft, with the densest mbuna populations typically concentrated between about 5 and 39 ft. Water conditions match Lake Malawi's standard littoral profile: warm, alkaline, and well-buffered.
Feeding
As with other Pseudotropheus, this form is expected to be a specialised algae grazer, rasping the aufwuchs mat — filamentous algae, diatoms, cyanobacteria and associated small invertebrates — from rock surfaces using the genus's typical dentition. No feeding study specific to this Membe Point population has been published, but this diet is close to universal across rock-dwelling Pseudotropheus and closely related mbuna genera sharing the same reef. Dense, multi-species mbuna assemblages of the kind documented around Likoma Island typically partition the same algal turf by subtle differences in bite angle, feeding depth and preferred rock texture rather than head-on competition for an identical resource, and this form most plausibly fits somewhere into that pattern alongside its many rock-dwelling neighbours, though the specifics have not been studied for it directly.
Mating
Breeding in this genus is polygynous, with territorial males holding rock or crevice sites and displaying to passing females rather than forming lasting pair bonds. Courtship is expected to follow the standard haplochromine pattern documented across Pseudotropheus: a male performs a quivering lateral display to a visiting female, and his anal-fin egg-spots draw her to peck at them after she has deposited her own eggs, fertilising the clutch she is already holding in her mouth. No courtship account specific to this population has been published.
Breeding
Pseudotropheus sp. "Lucerna Fin Spot" is presumed to be a maternal mouthbrooder, as are all Pseudotropheus. Following courtship, the female is expected to take the fertilised eggs into her mouth and brood them alone through to free-swimming fry, with no paternal care. No clutch data have been published for this specific form; the better-documented, similarly sized Pseudotropheus cyaneorhabdos, recorded from the same stretch of Likoma Island shoreline, produces clutches on the order of 10 to 30 eggs, brooded for roughly 18 to 21 days without feeding, and this population is presumed to fall in a broadly similar range, though that remains inference by local and genus analogy rather than a measured count for this form itself.
In the aquarium
"Lucerna Fin Spot" is a niche form with limited hobbyist documentation, generally sought by keepers specifically wanting a Likoma-area Pseudotropheus rather than a mainstream mbuna. Standard genus husbandry applies: dense rockwork with broken sightlines and more territories than the tank's male population, alkaline, well-buffered water, and a vegetable-leaning, algae-based diet to avoid the bloat risk common in over-fed rift-lake grazers. Because Membe Point also hosts the Critically Endangered Pseudotropheus cyaneorhabdos, keepers and collectors sourcing fish from this stretch of shore should take particular care over correct identification and avoid mixing look-alike species from the same reef.
Conservation
Pseudotropheus sp. "Lucerna Fin Spot" has no IUCN Red List assessment, because it has never been formally described and has no valid scientific name available to be assessed. Membe Point sits within the same narrow, single-island range documented for the Critically Endangered Pseudotropheus cyaneorhabdos, a status driven there by collection pressure for the ornamental trade on a very restricted population — a useful reminder that other locality-restricted mbuna sharing this same stretch of Likoma Island shore, this form included, face comparable exposure even though none has been formally assessed.