Problems of species definition in Lake Malawi cichlid fishes (Pisces: Cichlidae)
- Lewis, Digby S C, J.L.B. Smith Institute of Ichthyology
- Authors: Lewis, Digby S C , J.L.B. Smith Institute of Ichthyology
- Date: 1982-09
- Subjects: Cichlids -- Nyasa, Lake , Fishes
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/69918 , vital:29595 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 23 , The evolution of the cichlid species flock in Lake Malawi has taken place very rapidly and resulted in the proliferation of a large number of species many of which are similar to one another. This has given rise to a situation in which traditional methods of distinguishing species based on preserved specimens are often of limited value. There are many instances of different species having almost identical morphologies, of single populations of one species showing considerable morphological variation and of marked geographical intraspecific variation. Polymorphism is considered not to be as widespread as previously thought, and pronounced random intraspecific colour variation within a population is discounted. Sympatric sibling species may be distinguished by observing behavioural and habitat differences in the field, but no means has been devised for ascertaining whether morphologically and behaviourally similar allopatric forms are specifically distinct. Lack of access to fresh specimens and lack of information on distribution and habitat have resulted in numerous errors appearing in taxonomic works on Lake Malawi cichlids. Great care is needed when attempting scientific descriptions of cichlid species from the African Great Lakes, and it is suggested that such work be left to specialists with knowledge of living and fresh fish in these lakes.
- Full Text:
- Date Issued: 1982-09
- Authors: Lewis, Digby S C , J.L.B. Smith Institute of Ichthyology
- Date: 1982-09
- Subjects: Cichlids -- Nyasa, Lake , Fishes
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/69918 , vital:29595 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 23 , The evolution of the cichlid species flock in Lake Malawi has taken place very rapidly and resulted in the proliferation of a large number of species many of which are similar to one another. This has given rise to a situation in which traditional methods of distinguishing species based on preserved specimens are often of limited value. There are many instances of different species having almost identical morphologies, of single populations of one species showing considerable morphological variation and of marked geographical intraspecific variation. Polymorphism is considered not to be as widespread as previously thought, and pronounced random intraspecific colour variation within a population is discounted. Sympatric sibling species may be distinguished by observing behavioural and habitat differences in the field, but no means has been devised for ascertaining whether morphologically and behaviourally similar allopatric forms are specifically distinct. Lack of access to fresh specimens and lack of information on distribution and habitat have resulted in numerous errors appearing in taxonomic works on Lake Malawi cichlids. Great care is needed when attempting scientific descriptions of cichlid species from the African Great Lakes, and it is suggested that such work be left to specialists with knowledge of living and fresh fish in these lakes.
- Full Text:
- Date Issued: 1982-09
A taxonomic study of the Genus Lethrinops Regan (Pisces: Cichlidae) from Lake Malawi: part 3
- Eccles, David H, Lewis, Digby S C
- Authors: Eccles, David H , Lewis, Digby S C
- Date: 1979
- Subjects: Lethrinops -- Malawi, Lake -- Classification , Haplochromis -- Malawi, Lake -- Classification
- Language: English
- Type: Text
- Identifier: vital:15007 , http://hdl.handle.net/10962/d1019730 , ISBN 0868100021 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 38
- Description: The group of species considered all have short moderate snouts and a group of slightly to strongly enlarged teeth on the lower pharyngeal bone, the anterior and lateral teeth of which are biscupid, with the posterior cusp turned forwards. Lethrinops parvidens Trewavas, L. aurita (Regan), L. macrophthalmus (Boulenger), L. macrochir (Regan), L.longimanus Trewavas and L. macracanthus Trewavas are re-described, and L. mylodon n. sp. is described, the latter being divided into two geographically seperated sub-species. While L. longimanus and L. macracanthus co-exist with very slight overlap of morphological characters in the south of Lake Malawi, an apparently intermediate population is reported from another part of the Lake. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1979
- Authors: Eccles, David H , Lewis, Digby S C
- Date: 1979
- Subjects: Lethrinops -- Malawi, Lake -- Classification , Haplochromis -- Malawi, Lake -- Classification
- Language: English
- Type: Text
- Identifier: vital:15007 , http://hdl.handle.net/10962/d1019730 , ISBN 0868100021 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 38
- Description: The group of species considered all have short moderate snouts and a group of slightly to strongly enlarged teeth on the lower pharyngeal bone, the anterior and lateral teeth of which are biscupid, with the posterior cusp turned forwards. Lethrinops parvidens Trewavas, L. aurita (Regan), L. macrophthalmus (Boulenger), L. macrochir (Regan), L.longimanus Trewavas and L. macracanthus Trewavas are re-described, and L. mylodon n. sp. is described, the latter being divided into two geographically seperated sub-species. While L. longimanus and L. macracanthus co-exist with very slight overlap of morphological characters in the south of Lake Malawi, an apparently intermediate population is reported from another part of the Lake. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1979
The nature of the barriers separating the Lake Malawi and Zambezi fish faunas
- Tweddle, D S C, Lewis, Digby S C, Willoughby, N G
- Authors: Tweddle, D S C , Lewis, Digby S C , Willoughby, N G
- Date: 1979
- Language: English
- Type: Text
- Identifier: vital:15018 , http://hdl.handle.net/10962/d1019797 , ISBN 086810003X , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 39
- Description: Part 1: The nature of the barriers separating the Lake Malawi and Zambezi fish faunas: The nature of the barrier separating the ‘Lake Malawi’ from the ‘Lower Zambezi’ fish faunas was investigated by electrofishing the 145 km stretch of the Shire River surrounding the Murchison cataracts. The study shows that the lowermost element of the cataracts, the Kapachira Falls, is an absolute physical barrier to upstream movement of ‘Lower Zambezi’ species. The barrier to downstream movement by ‘Lake Malawi’ species is largely ecological and has two components, the fluviatile nature of the Upper and Middle Shire and especially the torrential nature of the cataracts, which are unsuitable for lacustrine species, and competition with the ‘Lower Zambezi’ fauna of the Lower Shire by the few species which succeed in negotiating the cataracts. , Part 2: An annotated checklist of the fish fauna of the River Shire south of Kapachira Falls, Malawi: The Shire River drains Lake Malawi and is a major tributary of the Lower Zambezi River. Sixty-one species of fish have been recorded in the lower reaches which are separated from the lower Shire basin by the Kapachira Falls and from the ‘East Coast River’ fauna present in the Upper Ruo River by the Zoa Falls. The fauna is essentially similar to that of the Lower Zambezi, although some Lake Malawi endemics occur sporadically in the upper part of the flood plain. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1979
- Authors: Tweddle, D S C , Lewis, Digby S C , Willoughby, N G
- Date: 1979
- Language: English
- Type: Text
- Identifier: vital:15018 , http://hdl.handle.net/10962/d1019797 , ISBN 086810003X , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 39
- Description: Part 1: The nature of the barriers separating the Lake Malawi and Zambezi fish faunas: The nature of the barrier separating the ‘Lake Malawi’ from the ‘Lower Zambezi’ fish faunas was investigated by electrofishing the 145 km stretch of the Shire River surrounding the Murchison cataracts. The study shows that the lowermost element of the cataracts, the Kapachira Falls, is an absolute physical barrier to upstream movement of ‘Lower Zambezi’ species. The barrier to downstream movement by ‘Lake Malawi’ species is largely ecological and has two components, the fluviatile nature of the Upper and Middle Shire and especially the torrential nature of the cataracts, which are unsuitable for lacustrine species, and competition with the ‘Lower Zambezi’ fauna of the Lower Shire by the few species which succeed in negotiating the cataracts. , Part 2: An annotated checklist of the fish fauna of the River Shire south of Kapachira Falls, Malawi: The Shire River drains Lake Malawi and is a major tributary of the Lower Zambezi River. Sixty-one species of fish have been recorded in the lower reaches which are separated from the lower Shire basin by the Kapachira Falls and from the ‘East Coast River’ fauna present in the Upper Ruo River by the Zoa Falls. The fauna is essentially similar to that of the Lower Zambezi, although some Lake Malawi endemics occur sporadically in the upper part of the flood plain. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1979
A taxonomic study of the Genus Lethrinops Regan (Pisces: Cichlidae) from Lake Malawi: part 2
- Eccles, David H, Lewis, Digby S C
- Authors: Eccles, David H , Lewis, Digby S C
- Date: 1978
- Subjects: Lethrinops -- Malawi, Lake -- Classification , Haplochromis -- Malawi, Lake -- Classification
- Language: English
- Type: Text
- Identifier: vital:14989 , http://hdl.handle.net/10962/d1018957 , ISBN 094998096x , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 37
- Description: Lethrinops argentea Ahl, L. lethrinus (Gunther) and L. leptodon Regan are re-described and illustrated. An additional new species, L. longipinnis, sharing with the above the possession a steeply sloping, wedge-shaped snout, a slender lower pharyngeal bone and few (9—14) gillrakers is described. The status of L. lunaris Trewavas is discussed. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1978
- Authors: Eccles, David H , Lewis, Digby S C
- Date: 1978
- Subjects: Lethrinops -- Malawi, Lake -- Classification , Haplochromis -- Malawi, Lake -- Classification
- Language: English
- Type: Text
- Identifier: vital:14989 , http://hdl.handle.net/10962/d1018957 , ISBN 094998096x , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 37
- Description: Lethrinops argentea Ahl, L. lethrinus (Gunther) and L. leptodon Regan are re-described and illustrated. An additional new species, L. longipinnis, sharing with the above the possession a steeply sloping, wedge-shaped snout, a slender lower pharyngeal bone and few (9—14) gillrakers is described. The status of L. lunaris Trewavas is discussed. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1978
A taxonomic study of the Genus Lethrinops Regan (Pisces: Cichlidae) from Lake Malawi: part 1
- Eccles, David H, Lewis, Digby S C
- Authors: Eccles, David H , Lewis, Digby S C
- Date: 1977
- Subjects: Lethrinops -- Malawi, Lake -- Classification , Haplochromis -- Malawi, Lake -- Classification
- Language: English
- Type: Text
- Identifier: vital:14988 , http://hdl.handle.net/10962/d1018956 , ISBN 949980854 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 36
- Description: Haplochromis micrentodon Regan is transferred to the genus Lethrinops and redescribed. Two new species of Lethrinops which, like the above, are characterised by the possession of lower pharyngeal bones bearing close pavements of slender blunt-tipped teeth are described. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1977
- Authors: Eccles, David H , Lewis, Digby S C
- Date: 1977
- Subjects: Lethrinops -- Malawi, Lake -- Classification , Haplochromis -- Malawi, Lake -- Classification
- Language: English
- Type: Text
- Identifier: vital:14988 , http://hdl.handle.net/10962/d1018956 , ISBN 949980854 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 36
- Description: Haplochromis micrentodon Regan is transferred to the genus Lethrinops and redescribed. Two new species of Lethrinops which, like the above, are characterised by the possession of lower pharyngeal bones bearing close pavements of slender blunt-tipped teeth are described. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1977
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