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Morphology, molecules, and monogenean parasites: an example of an integrative approach to cichlid biodiversity.

Van Steenberge M, Pariselle A, Huyse T, Volckaert FA, Snoeks J, Vanhove MP - PLoS ONE (2015)

Bottom Line: Cichlidogyrus georgesmertensi sp. nov. was found on S. babaulti and S. pleurospilus, C. franswittei sp. nov. on both S. marginatus and P. curvifrons and C. frankwillemsi sp. nov. only on P. curvifrons.As relatedness between Cichlidogyrus species usually reflects relatedness between hosts, we considered Simochromis monotypic because the three Cichlidogyrus species found on S. diagramma belonged to a different morphotype than those found on the other Simochromis.Finally parasite data also supported the synonymy between S. pleurospilus and S. babaulti, a species that contains a large amount of geographical morphological variation.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Royal Museum for Central Africa, Tervuren, Belgium; Laboratory of Biodiversity and Evolutionary Genomics, Department of Biology, University of Leuven, Leuven, Belgium; Institute of Zoology, University of Graz, Graz, Austria.

ABSTRACT
The unparalleled biodiversity of Lake Tanganyika (Africa) has fascinated biologists for over a century; its unique cichlid communities are a preferred model for evolutionary research. Although species delineation is, in most cases, relatively straightforward, higher-order classifications were shown not to agree with monophyletic groups. Here, traditional morphological methods meet their limitations. A typical example are the tropheine cichlids currently belonging to Simochromis and Pseudosimochromis. The affiliations of these widespread and abundant cichlids are poorly understood. Molecular work suggested that genus and species boundaries should be revised. Moreover, previous morphological results indicated that intraspecific variation should be considered to delineate species in Lake Tanganyika cichlids. We review the genera Simochromis and Pseudosimochromis using an integrative approach. Besides a morphometric study and a barcoding approach, monogenean Cichlidogyrus (Platyhelminthes: Ancyrocephalidae) gill parasites, often highly species-specific, are used as complementary markers. Six new species are described. Cichlidogyrus raeymaekersi sp. nov., C. muterezii sp. nov. and C. banyankimbonai sp. nov. infect S. diagramma. Cichlidogyrus georgesmertensi sp. nov. was found on S. babaulti and S. pleurospilus, C. franswittei sp. nov. on both S. marginatus and P. curvifrons and C. frankwillemsi sp. nov. only on P. curvifrons. As relatedness between Cichlidogyrus species usually reflects relatedness between hosts, we considered Simochromis monotypic because the three Cichlidogyrus species found on S. diagramma belonged to a different morphotype than those found on the other Simochromis. The transfer of S. babaulti, S. marginatus, S. pleurospilus and S. margaretae to Pseudosimochromis was justified by the similarity of their Cichlidogyrus fauna and the intermediate morphology of S. margaretae. Finally parasite data also supported the synonymy between S. pleurospilus and S. babaulti, a species that contains a large amount of geographical morphological variation.

No MeSH data available.


Gill arches of Simochromis and Pseudosimochromis species.From left to right: P. curvifrons, S. babaulti, S. marginatus, S. margaretae and S. diagramma. Specimens illustrated are listed in Appendix.
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pone.0124474.g003: Gill arches of Simochromis and Pseudosimochromis species.From left to right: P. curvifrons, S. babaulti, S. marginatus, S. margaretae and S. diagramma. Specimens illustrated are listed in Appendix.

Mentions: When the shape of the gill rakers was taken into account, the two main groups identified by PC1 could be separated. Indeed, whereas in S. marginatus, S. babaulti, S. pleurospilus and S. margaretae there was a clear transition between the blunt reduced and the sharp non-reduced gill rakers, this was not the case in S. diagramma or in P. curvifrons (Fig 3). In the latter species, reduced gill rakers were never observed and sharp gill rakers were present up until the anteriormost part of the first lower gill arch. In S. babaulti and S. pleurospilus the difference between the non-reduced and the reduced gill rakers was the most striking and the reduced gill rakers could only be observed by their different refraction of light [72]. The anteriormost of the non-reduced gill rakers, however, was always visible as protruding out of the fleshy tissue. A similar situation was encountered in S. marginatus although, in this species, some of the reduced gill rakers protruded slightly, but were still blunt. In the two S. margaretae paratypes, the two anteriormost lower gill rakers differed from the seven other gill rakers both by their smaller size and by their blunt shape. Yet, they were more developed than in the other ‘small’ Simochromis species and clearly visible. In S. diagramma, the anteriormost lower gill rakers were small but there was a gradual transition between the long villiform lower gill rakers dorsally and the short gill rakers ventrally. Also, all gill rakers clearly protruded from the fleshy tissue. In P. curvifrons, a similar gradual reduction in size was encountered although with less difference in shape as all gill rakers were relatively short. Hence, the number of sharp non-reduced lower gill rakers (4–8 vs. 10–13) separated the small Simochromis species from S. diagramma and P. curvifrons.


Morphology, molecules, and monogenean parasites: an example of an integrative approach to cichlid biodiversity.

Van Steenberge M, Pariselle A, Huyse T, Volckaert FA, Snoeks J, Vanhove MP - PLoS ONE (2015)

Gill arches of Simochromis and Pseudosimochromis species.From left to right: P. curvifrons, S. babaulti, S. marginatus, S. margaretae and S. diagramma. Specimens illustrated are listed in Appendix.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414595&req=5

pone.0124474.g003: Gill arches of Simochromis and Pseudosimochromis species.From left to right: P. curvifrons, S. babaulti, S. marginatus, S. margaretae and S. diagramma. Specimens illustrated are listed in Appendix.
Mentions: When the shape of the gill rakers was taken into account, the two main groups identified by PC1 could be separated. Indeed, whereas in S. marginatus, S. babaulti, S. pleurospilus and S. margaretae there was a clear transition between the blunt reduced and the sharp non-reduced gill rakers, this was not the case in S. diagramma or in P. curvifrons (Fig 3). In the latter species, reduced gill rakers were never observed and sharp gill rakers were present up until the anteriormost part of the first lower gill arch. In S. babaulti and S. pleurospilus the difference between the non-reduced and the reduced gill rakers was the most striking and the reduced gill rakers could only be observed by their different refraction of light [72]. The anteriormost of the non-reduced gill rakers, however, was always visible as protruding out of the fleshy tissue. A similar situation was encountered in S. marginatus although, in this species, some of the reduced gill rakers protruded slightly, but were still blunt. In the two S. margaretae paratypes, the two anteriormost lower gill rakers differed from the seven other gill rakers both by their smaller size and by their blunt shape. Yet, they were more developed than in the other ‘small’ Simochromis species and clearly visible. In S. diagramma, the anteriormost lower gill rakers were small but there was a gradual transition between the long villiform lower gill rakers dorsally and the short gill rakers ventrally. Also, all gill rakers clearly protruded from the fleshy tissue. In P. curvifrons, a similar gradual reduction in size was encountered although with less difference in shape as all gill rakers were relatively short. Hence, the number of sharp non-reduced lower gill rakers (4–8 vs. 10–13) separated the small Simochromis species from S. diagramma and P. curvifrons.

Bottom Line: Cichlidogyrus georgesmertensi sp. nov. was found on S. babaulti and S. pleurospilus, C. franswittei sp. nov. on both S. marginatus and P. curvifrons and C. frankwillemsi sp. nov. only on P. curvifrons.As relatedness between Cichlidogyrus species usually reflects relatedness between hosts, we considered Simochromis monotypic because the three Cichlidogyrus species found on S. diagramma belonged to a different morphotype than those found on the other Simochromis.Finally parasite data also supported the synonymy between S. pleurospilus and S. babaulti, a species that contains a large amount of geographical morphological variation.

View Article: PubMed Central - PubMed

Affiliation: Biology Department, Royal Museum for Central Africa, Tervuren, Belgium; Laboratory of Biodiversity and Evolutionary Genomics, Department of Biology, University of Leuven, Leuven, Belgium; Institute of Zoology, University of Graz, Graz, Austria.

ABSTRACT
The unparalleled biodiversity of Lake Tanganyika (Africa) has fascinated biologists for over a century; its unique cichlid communities are a preferred model for evolutionary research. Although species delineation is, in most cases, relatively straightforward, higher-order classifications were shown not to agree with monophyletic groups. Here, traditional morphological methods meet their limitations. A typical example are the tropheine cichlids currently belonging to Simochromis and Pseudosimochromis. The affiliations of these widespread and abundant cichlids are poorly understood. Molecular work suggested that genus and species boundaries should be revised. Moreover, previous morphological results indicated that intraspecific variation should be considered to delineate species in Lake Tanganyika cichlids. We review the genera Simochromis and Pseudosimochromis using an integrative approach. Besides a morphometric study and a barcoding approach, monogenean Cichlidogyrus (Platyhelminthes: Ancyrocephalidae) gill parasites, often highly species-specific, are used as complementary markers. Six new species are described. Cichlidogyrus raeymaekersi sp. nov., C. muterezii sp. nov. and C. banyankimbonai sp. nov. infect S. diagramma. Cichlidogyrus georgesmertensi sp. nov. was found on S. babaulti and S. pleurospilus, C. franswittei sp. nov. on both S. marginatus and P. curvifrons and C. frankwillemsi sp. nov. only on P. curvifrons. As relatedness between Cichlidogyrus species usually reflects relatedness between hosts, we considered Simochromis monotypic because the three Cichlidogyrus species found on S. diagramma belonged to a different morphotype than those found on the other Simochromis. The transfer of S. babaulti, S. marginatus, S. pleurospilus and S. margaretae to Pseudosimochromis was justified by the similarity of their Cichlidogyrus fauna and the intermediate morphology of S. margaretae. Finally parasite data also supported the synonymy between S. pleurospilus and S. babaulti, a species that contains a large amount of geographical morphological variation.

No MeSH data available.