. Bulletin of the British Museum (Natural History). Zoology . EVOLUTION OF A CICHLID SPECIES FLOCK 67 stem, the other (H. erythrocephalus) is part of a lineage whose living basal representa- tive is probably H. empodisma. Haplochromis phytophagus, a browser on macro- phytes, could belong to the same lineage as H. cinctus ; like those species its dentition shows little departure from the generalized type, but it does have the same alimentary canal specializations. Possibly the three species are an offshoot of the lineage cul- minating in the periphyton grazers (Text-figs 65 and 70)
. Bulletin of the British Museum (Natural History). Zoology . EVOLUTION OF A CICHLID SPECIES FLOCK 67 stem, the other (H. erythrocephalus) is part of a lineage whose living basal representa- tive is probably H. empodisma. Haplochromis phytophagus, a browser on macro- phytes, could belong to the same lineage as H. cinctus ; like those species its dentition shows little departure from the generalized type, but it does have the same alimentary canal specializations. Possibly the three species are an offshoot of the lineage cul- minating in the periphyton grazers (Text-figs 65 and 70). There remains one other species, H. acidens (Greenwood, 1967), which, like H. phytophagus, feeds directly on macrophytes. The skull, jaws and unicuspid dentition (Text-fig. 37) of this species conform with the type found among a group of specialized piscivorous predators (Greenwood, op. cit.), as does the pharyngeal dentition. Furthermore, despite the vegetarian habitats of H. acidens, its intestine is relatively shorter than in other plant-eating species, although it is longer than in a piscivore. Fig. 37. Neurocranium and lower jaw of the enigmatic H. acidens (see p. 41). (Scale = 3 mm.) I have suggested elsewhere (Greenwood, 1967) that, anatomically, H. acidens could be a member of a particular piscivore lineage (the ' serranus' group, see Green- wood, 1962). It could also be a derivative from an H. empodisma-like species ; the principal change involved would be an increase in the relative number of uni- cuspid teeth so that these teeth predominate over bicuspids in both jaws (there is an admixture of bi- and unicuspids in large H. empodisma [ > 95 mm long] and in H. acidens < 90 mm in length). In both species the teeth, irrespective of cusp form, are slender in comparison with those of the generalized type. Considering the rather indefinite feeding habits of H. empodisma (a benthic insectivore also ingesting quanti- ties of plant debris) and the interspecific si
Size: 2866px × 872px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
