. Bulletin of the British Museum (Natural History) Zoology. 46 GREENWOOD dentigerous body. In fishes less than 40 mm this part of the bone is not noticeably enlarged but above that size, and when compared with, for example, specimens of Astatotila- pia, Chetia and Serranochromis (Serranochromis) species the bone is distinctly coarser and more massive. Indeed, that comparison can be extended to include certain species of Serranochromis (Sargochromis) such as S.(S) gracilis and S.(S.) greenwoodi. In a few individuals of Pharyngochromis acuticeps over mm , the enlargement can a
. Bulletin of the British Museum (Natural History) Zoology. 46 GREENWOOD dentigerous body. In fishes less than 40 mm this part of the bone is not noticeably enlarged but above that size, and when compared with, for example, specimens of Astatotila- pia, Chetia and Serranochromis (Serranochromis) species the bone is distinctly coarser and more massive. Indeed, that comparison can be extended to include certain species of Serranochromis (Sargochromis) such as S.(S) gracilis and S.(S.) greenwoodi. In a few individuals of Pharyngochromis acuticeps over mm , the enlargement can approach or slightly exceed that in comparable sized or even larger S.(S.) coulteri (see figs in Greenwood, 1979 and 1984). The articulatory horns of the lower pharyngeal bone are generally short and stout, but as with the body of the bone (and usually correlated with the degree of hypertrophy in that region) there is some intraspecific variability in their stout- ness. The suture joining the two halves of the bone can be straight and simple, or more often, deeply sinuous. The lower pharyngeal teeth and changes in their form and size have already been described (see p. 38). It only remains to note that even within one size group, and within a single locality, there is some variability both in the number of enlarged teeth in the median rows and in the degree of molarization shown by these teeth. Greatly enlarged, and much flattened molariform teeth such as occur in many species of Serranochromis (Sargochromis), are not found in P. acuticeps, and only rarely are all the teeth in the row next to each median row enlarged with mammilar crowns (see p. 38). Vertebral column. Counts were obtained from radiographs of 68 specimens, including the lectotype and one paralectotype of the species, and the holotypes of Chromis jallae, Pelma- tochromis multiocellatus and Pelmatochromis darlingi. The geographical range of these various specimens includes the Okavango region, the Zambezi and Save-
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