A revision of the blue-black Pseudotropheus zebra (Teleostei: Cichlidae) complex from Lake Malawi, Africa, with a description of a new genus and ten new species

A new genus, Metriaclima, is described for members of the Pseudotropheus zebra complex from Lake Malawi. The presence of bicuspid teeth in the anterior portion of the outer row of both the upper and lower jaws distinguishes Metriaclima from many of the previously described genera of rock-dwelling cichlids that inhabit Lake Malawi, including Cyathochromis, Cynotilapia, Gephyrochromis, Labidochromis, and Petrotilapia. The absence of two horizontal stripes along its flanks, distinguishes it from Melanochromis. The isognathous jaws of Metriaclima delimits it from Genyochromis, which is characterized by having the lower jaw extend in front, of the upper jaw. The mouth of Metriaclima is terminal, while that of Labeotropheus is inferior. Within the genus Pseudotropheus as it is now recognized, species of Metriaclima are unique because they have a moderately sloped ethmo-vomerine block and a swollen rostral tip. Ten previously undescribed species that have a slight variation from the characteristic blue/black barring are described. The new species are recognized primarily by their distinctive adult coloring in conjunction with the discontinuity of morphological differences throughout their range.