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†Kenyaichthyidae fam. nov. and †Kenyaichthys gen. nov. - First Record of a Fossil Aplocheiloid Killifish (Teleostei, Cyprinodontiformes).

Altner M, Reichenbacher B - PLoS ONE (2015)

Bottom Line: The phylogenetic analysis unexpectedly places †Kenyaichthys gen. nov. in a sister relationship to the Rivulidae (a purely Neotropical group), a probable explanation might be lack of available synapomorphies for the Rivulidae, Nothobranchiidae and Aplocheilidae.The specimens of †K. kipkechi sp. nov. show several polymorphic characters and large overlap in meristic traits, which justifies their interpretation as a species flock in statu nascendi.Patterns of variation in neural and haemal spine dimensions in the caudal vertebrae of †Kenyaichthys gen. nov. and the extant species studied indicate that some previously suggested synapomorphies of the Cyprinodontoidei and Aplocheiloidei need to be revised.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth- and Environmental Sciences, Palaeontology & Geobiology, Ludwig-Maximilians-University, Munich, Germany.

ABSTRACT
The extant Cyprinodontiformes (killifishes) with their two suborders Cyprinodontoidei and Aplocheiloidei represent a diverse and well-studied group of fishes. However, their fossil record is comparatively sparse and has so far yielded members of the Cyprinodontoidei only. Here we report on cyprinodontiform fossils from the upper Miocene Lukeino Formation in the Tugen Hills of the Central Rift Valley of Kenya, which represent the first fossil record of an aplocheiloid killifish. A total of 169 specimens - mostly extraordinarily well preserved - and a sample of ten extant cyprinodontiform species were studied on the basis of morphometrics, meristics and osteology. A phylogenetic analysis using PAUP was also conducted for the fossils. Both the osteological data and the phylogenetic analysis provide strong evidence for the assignment of the fossils to the Aplocheiloidei, and justify the definition of the new family †Kenyaichthyidae, the new genus †Kenyaichthys and the new species †K. kipkechi sp. nov. The phylogenetic analysis unexpectedly places †Kenyaichthys gen. nov. in a sister relationship to the Rivulidae (a purely Neotropical group), a probable explanation might be lack of available synapomorphies for the Rivulidae, Nothobranchiidae and Aplocheilidae. The specimens of †K. kipkechi sp. nov. show several polymorphic characters and large overlap in meristic traits, which justifies their interpretation as a species flock in statu nascendi. Patterns of variation in neural and haemal spine dimensions in the caudal vertebrae of †Kenyaichthys gen. nov. and the extant species studied indicate that some previously suggested synapomorphies of the Cyprinodontoidei and Aplocheiloidei need to be revised.

No MeSH data available.


Details of the anal fin of †Kenyaichthys kipkechi sp. nov. (paratype 1177´04).A1–A2 Anal fin with three short rays, 17 long rays and 19 proximal radials (last ray not supported by proximal radial), left lateral view. Abbreviations: ab, branched rays of anal fin; amr, anal medial radial; apr-1, first anal proximal radial; au-1, first unbranched anal fin ray; hs, haemal spine.
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pone.0123056.g008: Details of the anal fin of †Kenyaichthys kipkechi sp. nov. (paratype 1177´04).A1–A2 Anal fin with three short rays, 17 long rays and 19 proximal radials (last ray not supported by proximal radial), left lateral view. Abbreviations: ab, branched rays of anal fin; amr, anal medial radial; apr-1, first anal proximal radial; au-1, first unbranched anal fin ray; hs, haemal spine.

Mentions: The anal fin is slightly larger than the dorsal, and is inserted opposite, slightly behind or in front of the dorsal fin insertion (preanal distance 59.6 ± 2.5, see Table 1). It comprises 16–22 rays, of which only the first up to three are clearly seen to be short and unbranched; each ray (branched or unbranched), generally with the exception of the last, is supported by a single long proximal radial, small medial radials are also recognizable (Table 2 and S3 Table, Fig 8).


†Kenyaichthyidae fam. nov. and †Kenyaichthys gen. nov. - First Record of a Fossil Aplocheiloid Killifish (Teleostei, Cyprinodontiformes).

Altner M, Reichenbacher B - PLoS ONE (2015)

Details of the anal fin of †Kenyaichthys kipkechi sp. nov. (paratype 1177´04).A1–A2 Anal fin with three short rays, 17 long rays and 19 proximal radials (last ray not supported by proximal radial), left lateral view. Abbreviations: ab, branched rays of anal fin; amr, anal medial radial; apr-1, first anal proximal radial; au-1, first unbranched anal fin ray; hs, haemal spine.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414574&req=5

pone.0123056.g008: Details of the anal fin of †Kenyaichthys kipkechi sp. nov. (paratype 1177´04).A1–A2 Anal fin with three short rays, 17 long rays and 19 proximal radials (last ray not supported by proximal radial), left lateral view. Abbreviations: ab, branched rays of anal fin; amr, anal medial radial; apr-1, first anal proximal radial; au-1, first unbranched anal fin ray; hs, haemal spine.
Mentions: The anal fin is slightly larger than the dorsal, and is inserted opposite, slightly behind or in front of the dorsal fin insertion (preanal distance 59.6 ± 2.5, see Table 1). It comprises 16–22 rays, of which only the first up to three are clearly seen to be short and unbranched; each ray (branched or unbranched), generally with the exception of the last, is supported by a single long proximal radial, small medial radials are also recognizable (Table 2 and S3 Table, Fig 8).

Bottom Line: The phylogenetic analysis unexpectedly places †Kenyaichthys gen. nov. in a sister relationship to the Rivulidae (a purely Neotropical group), a probable explanation might be lack of available synapomorphies for the Rivulidae, Nothobranchiidae and Aplocheilidae.The specimens of †K. kipkechi sp. nov. show several polymorphic characters and large overlap in meristic traits, which justifies their interpretation as a species flock in statu nascendi.Patterns of variation in neural and haemal spine dimensions in the caudal vertebrae of †Kenyaichthys gen. nov. and the extant species studied indicate that some previously suggested synapomorphies of the Cyprinodontoidei and Aplocheiloidei need to be revised.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth- and Environmental Sciences, Palaeontology & Geobiology, Ludwig-Maximilians-University, Munich, Germany.

ABSTRACT
The extant Cyprinodontiformes (killifishes) with their two suborders Cyprinodontoidei and Aplocheiloidei represent a diverse and well-studied group of fishes. However, their fossil record is comparatively sparse and has so far yielded members of the Cyprinodontoidei only. Here we report on cyprinodontiform fossils from the upper Miocene Lukeino Formation in the Tugen Hills of the Central Rift Valley of Kenya, which represent the first fossil record of an aplocheiloid killifish. A total of 169 specimens - mostly extraordinarily well preserved - and a sample of ten extant cyprinodontiform species were studied on the basis of morphometrics, meristics and osteology. A phylogenetic analysis using PAUP was also conducted for the fossils. Both the osteological data and the phylogenetic analysis provide strong evidence for the assignment of the fossils to the Aplocheiloidei, and justify the definition of the new family †Kenyaichthyidae, the new genus †Kenyaichthys and the new species †K. kipkechi sp. nov. The phylogenetic analysis unexpectedly places †Kenyaichthys gen. nov. in a sister relationship to the Rivulidae (a purely Neotropical group), a probable explanation might be lack of available synapomorphies for the Rivulidae, Nothobranchiidae and Aplocheilidae. The specimens of †K. kipkechi sp. nov. show several polymorphic characters and large overlap in meristic traits, which justifies their interpretation as a species flock in statu nascendi. Patterns of variation in neural and haemal spine dimensions in the caudal vertebrae of †Kenyaichthys gen. nov. and the extant species studied indicate that some previously suggested synapomorphies of the Cyprinodontoidei and Aplocheiloidei need to be revised.

No MeSH data available.