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The rock-dwelling cichlids from Lake Malaŵi, known as mbuna, comprise a diverse group of haplochromine fishes that are placed among 14 genera. Within the mbuna, Pseudotropheus is a polyphyletic genus, which has served as a catch-all for many of these fishes. Recently, many of the species-groups within Pseudotropheus have been elevated to separate genera. Herein, we describe an elongate form that was originally placed in the Pseudotropheus elongatus species group but is now described as a member of Metriaclima.

Metriaclima is the most speciose genus of rock-dwelling fishes (mbuna) found in Lake Malaŵi with 32 described species and with about 40 recognized forms that still await formal description. The genus is comprised of many geographically narrow populations restricted to specific habitat landmarks, such as reefs or islands. A few species have taken to the open sandy habitat where empty gastropod shells provide shelter. Two species of such shell-dwellers are here described as new. A combination of a black submarginal band in the dorsal and anal fins and five or fewer bars on the flank distinguishes Metriaclima ngarae sp. n. and M. gallireyae sp. n. from all other species of Metriaclima. Metriaclima ngarae sp. n. differs from M. gallireyae by a greater interorbital width and by a greater ratio of the snout length in the distance between snout tip and pelvic fin origin. Adult males of M. gallireyae have a blue-brown overall coloration obscuring the bar pattern on the flank while males of M. ngarae and those of the closely related M. lanisticola retain the bar pattern and have a coloration very similar to that of females.

A species of haplochromine cichlid fish of the genus Diplotaxodon Trewavas, endemic to Lake Malaŵi is described: Diplotaxodon dentatus, new species. All eight type specimens were trawled together off Thumbi East Island in the Southeastern arm of the lake at 73 meters in 1985. They were initially identified as D. argenteus because the teeth on the oral jaws were fully exposed with a closed mouth. The shorter snout length of D. dentatus (26.6–29.2 % HL) clearly separates it from D. argenteus (31.7–34.2 % HL). A plot of a principal components analysis further supports the separation of D. dentatus from D. argenteus.

Lake Malawi is known for its endemic haplochromine species flock, most notably the rock-dwelling cichlids known as mbuna. The group of mbuna referred to as the Pseudotropheus elongatus species group is currently comprised of Metriaclima spp., Tropheops spp., Cynotilapia spp., and Pseudotropheus spp. In this study, Chindongo , a new genus with the type species C. bellicosus , is described for additional species in this group. Chindongo is distinguished from other mbuna genera by 1) the presence of bicuspid teeth in the anterior portion of the outer row of both upper and lower jaw; 2) a moderately to steeply sloped vomer with a narrow rostral tip which makes an angle of between 53° and 68° with the parasphenoid; 3) a small mouth with the lower jaw slightly shorter than the upper; 4) a broad anterior dentigerous area on both premaxilla and dentary with three or more rows of teeth (usually 5–6 rows); 5) a flank melanin pattern consisting of vertical bars without horizontal elements at any stage of development. Chindongo bellicosus is distinguished by its color pattern and shallower body from the other species which we have transferred to Chindongo . We also describe six new elongate mbuna species and place them into three available genera, they include: Metriaclima flavicauda , M. usisyae , Tropheops kumwera , T. biriwera , T. kamtambo , and Cynotilapia chilundu .

Pseudotropheus livingstonii and P. elegans are two sand-dwelling cichlid species that belong to the so-called mbuna, a group of predominantly rock-dwelling haplochromines of Lake Malaŵi. The identity of these two species has confused taxonomists for almost a century until a recent rediscovery of representatives of P. elegans close to its type locality. New diagnoses for both species are provided.

Lake Malaŵi is known for its endemic haplochromine species flock, most notably the rock-dwelling cichlids known as mbuna. One of the larger genera of mbuna is Metriaclima, a group consisting of 31 described species (including the five described herein) and approximately 45 recognized unique populations. Metriaclima is diagnosed by its feeding behavior and several morphological characteristics including the angle of the vomer and the presence of bicuspid teeth in the outer row of both the upper and lower jaws. Metriaclima zebra, the type species for the genus, was described based on a single specimen. While the collection location of this holotype is not known, based on the travel records of its collector, it is likely that the specimen originated from Likoma Island. The holotype was therefore compared to specimens from several localities around this island and was found to be morphologically indistinguishable from some of these. This study includes the morphological analysis of 496 specimens of Metriaclima belonging to 31 collections from Lake Malaŵi. Morphometric differences were analyzed and the relationships among several distinguishable populations of Metriaclima zebra were investigated. Our study further resulted in the description of the following five new species belonging to the M. zebra species complex: M. pambazuko, M. lundoense, M. midomo, M. tarakiki, and M. nigrodorsalis. These species were distinguished and described based on color patterns, morphometric, meristic, and ecological differences. These new species were compared with and distinguished from nearby populations of Metriaclima having similar pigmentation patterns and/or similar ecological niches. An artificial dichotomous key to the described species of Metriaclima is presented.

Lake Mala i is known for its endemic haplochromine species flock, most notably the rock-dwelling cichlids known as mbuna. One of the larger genera of mbuna is Metriaclima, a group consisting of 31 described species (including the five described herein) and approximately 45 recognized unique populations. Metriaclima is diagnosed by its feeding behavior and several morphological characteristics including the angle of the vomer and the presence of bicuspid teeth in the outer row of both the upper and lower jaws. Metriaclima zebra, the type species for the genus, was described based on a single specimen. While the collection location of this holotype is not known, based on the travel records of its collector, it is likely that the specimen originated from Likoma Island. The holotype was therefore compared to specimens from several localities around this island and was found to be morphologically indistinguishable from some of these. This study includes the morphological analysis of 496 specimens of Metriaclima belonging to 31 collections from Lake Mala i. Morphometric differences were analyzed and the relationships among several distinguishable populations of Metriaclima zebra were investigated. Our study further resulted in the description of the following five new species belonging to the M. zebra species complex: M. pambazuko, M. lundoense, M. midomo, M. tarakiki, and M. nigrodorsalis. These species were distinguished and described based on color patterns, morphometric, meristic, and ecological differences. These new species were compared with and distinguished from nearby populations of Metriaclima having similar pigmentation patterns and/or similar ecological niches. An artificial dichotomous key to the described species of Metriaclima is presented.