. Bulletin of the Natural History Museum Zoology. THE SERRANOCHROMINE GENERA REVIEWED 37 characters that are not present in Sargochromis or Pharyn- gochromis, the two other serranochromines with only a single postorbital scale row. These correlated features are an increase in the relative size and bulk of the upper part of the levator arcus palatini muscle, and an anteriorly directed lengthening of the postorbital process from the sphenotic bone, particularly its ventral region associated with the origin of the muscle (see fig. 3 and fig. 8 in Greenwood, 1992). In Sargochromis and Pharyngochro
. Bulletin of the Natural History Museum Zoology. THE SERRANOCHROMINE GENERA REVIEWED 37 characters that are not present in Sargochromis or Pharyn- gochromis, the two other serranochromines with only a single postorbital scale row. These correlated features are an increase in the relative size and bulk of the upper part of the levator arcus palatini muscle, and an anteriorly directed lengthening of the postorbital process from the sphenotic bone, particularly its ventral region associated with the origin of the muscle (see fig. 3 and fig. 8 in Greenwood, 1992). In Sargochromis and Pharyngochromis the muscle is relatively smaller, and the postorbital sphenotic process has the almost uniformly narrow form (Fig. 3) found in the generalised haplochromine skull (and, it may be added, the skulls of Tylochromis and Heterochromis, the genera thought to repre- sent the least derived lineages of African cichlids; see Oliver, 1984, and Stiassny, 1989 & 1991). The other reason for reconsidering the subgeneric status of Sargochromis is the increased information now available, especially for Chetia (see p. 38), which clearly indicates an extensive overlap in the gill-raker and dorsal fin-ray charac- ters previously used (Greenwood, 1979) to define Serrano- chromis (then including Sargochromis). These characters, therefore, no longer can be considered synapomorphic for Serranochromis and Sargochromis alone. With the elimination of those two characters, the only derived feature shared uniquely by Serranochromis and Sar- gochromis is the increased number of abdominal vertebrae. Against that presumed synapomorphy must be set the derived postorbital scale-row character shared only by Serra- nochromis (sensu Regan, 1920) and Chetia, which genera also share two apomorphic features not previously recognised. These are: (i) an increase in the range and modal number of caudal vertebrae (range 15-18, modes 16 and 17 in Serrano- chromis, range 15-17 modes 16 and 17 in Chetia, compared wi
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