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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.


Related in: MedlinePlus

Anatomical details of †Kenyaichthys.A1–A3 Anatomical details of †K. kipkechi sp. nov. (paratype 1237R(1)´04): A1–A2 Head and pectoral girdle, left lateral view; A3 Caudal fin rays covered with a single scale (arrow), left lateral view; B Head of †K. kipkechi sp. nov. (paratype 1160b´04), right dorsolateral view; C Disarticulated premaxilla and maxilla of †Kenyaichthys cf. kipkechi (1226a(1)´04), right lateral view; D1–D4 Anatomical details of †K. kipkechi (paratype 1209a/b´05): D1 Head and anterior part of body (1192a´05), arrow indicates lateral processes and spine of the first vertebra, left lateral view; D2 Schematic reconstruction of the first vertebra (paratype 1192a/b´05), anterior view; D3 Reconstruction of vertebrae 1–3 with pleural ribs and rod-shaped epipleural ribs (1192b´05), left lateral view; D4 Head and anterior part of body (1192b´05) with epipleural ribs on vertebrae 1–5, left lateral view. Abbreviations: apl, autopalatinum; br, branchiostegal rays; cer, ceratohyal; cl, cleithrum; den, dentary; end, endopterygoid; epl, epipleural rib; fro, frontal; hyo, hyomandibula; lp, lateral process; max, maxilla; met, metapterygoid; na-1, neural arch of first vertebra; ns, neural spine; op, operculum; pas, parasphenoid; pl, pleural rib; pmx, premaxilla; pop, preoperculum; ptt, posttemporal; qua, quadratum; sym, symplectic.
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pone.0123056.g004: Anatomical details of †Kenyaichthys.A1–A3 Anatomical details of †K. kipkechi sp. nov. (paratype 1237R(1)´04): A1–A2 Head and pectoral girdle, left lateral view; A3 Caudal fin rays covered with a single scale (arrow), left lateral view; B Head of †K. kipkechi sp. nov. (paratype 1160b´04), right dorsolateral view; C Disarticulated premaxilla and maxilla of †Kenyaichthys cf. kipkechi (1226a(1)´04), right lateral view; D1–D4 Anatomical details of †K. kipkechi (paratype 1209a/b´05): D1 Head and anterior part of body (1192a´05), arrow indicates lateral processes and spine of the first vertebra, left lateral view; D2 Schematic reconstruction of the first vertebra (paratype 1192a/b´05), anterior view; D3 Reconstruction of vertebrae 1–3 with pleural ribs and rod-shaped epipleural ribs (1192b´05), left lateral view; D4 Head and anterior part of body (1192b´05) with epipleural ribs on vertebrae 1–5, left lateral view. Abbreviations: apl, autopalatinum; br, branchiostegal rays; cer, ceratohyal; cl, cleithrum; den, dentary; end, endopterygoid; epl, epipleural rib; fro, frontal; hyo, hyomandibula; lp, lateral process; max, maxilla; met, metapterygoid; na-1, neural arch of first vertebra; ns, neural spine; op, operculum; pas, parasphenoid; pl, pleural rib; pmx, premaxilla; pop, preoperculum; ptt, posttemporal; qua, quadratum; sym, symplectic.

Mentions: Small fishes, ranging in size from 22 to 40 mm total length (TL), and 20 to 36 mm standard length (SL) (see Table 1 and S1 Table for measurements). Most specimens are preserved in lateral view, indicating that the body is elongate and laterally compressed. Body height reaches a maximum between the posterior margin of the head and the origin of the pectoral fin, and ranges from 16–28% of SL. The minimum body height, ranging from 6–12% SL, lies at the middle of the caudal peduncle. Head length ranges from 25–34% SL; the lateral profile from the snout to the occiput is asymmetrical, with a weakly rising long anterior part, and a curving short posterior part (Fig 3). The snout is slightly pointed, with the lower jaw slightly longer than the upper (superior mouth) (see Table 1, S1 Table and Fig 3). The caudal peduncle is long and elongate (22–30% SL), and reveals a slightly concave ventral and dorsal profile (Fig 3A1). The caudal fin ranges in size from 8 to 17% SL and is rounded to truncate (Fig 3A7). Cycloid scales are visible on the whole body and parts of the head (operculum, preoperculum, frontals), but not on the fins, with the exception of a few scales on the caudal fin base (Fig 4A3).


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

Altner M, Reichenbacher B - PLoS ONE (2015)

Anatomical details of †Kenyaichthys.A1–A3 Anatomical details of †K. kipkechi sp. nov. (paratype 1237R(1)´04): A1–A2 Head and pectoral girdle, left lateral view; A3 Caudal fin rays covered with a single scale (arrow), left lateral view; B Head of †K. kipkechi sp. nov. (paratype 1160b´04), right dorsolateral view; C Disarticulated premaxilla and maxilla of †Kenyaichthys cf. kipkechi (1226a(1)´04), right lateral view; D1–D4 Anatomical details of †K. kipkechi (paratype 1209a/b´05): D1 Head and anterior part of body (1192a´05), arrow indicates lateral processes and spine of the first vertebra, left lateral view; D2 Schematic reconstruction of the first vertebra (paratype 1192a/b´05), anterior view; D3 Reconstruction of vertebrae 1–3 with pleural ribs and rod-shaped epipleural ribs (1192b´05), left lateral view; D4 Head and anterior part of body (1192b´05) with epipleural ribs on vertebrae 1–5, left lateral view. Abbreviations: apl, autopalatinum; br, branchiostegal rays; cer, ceratohyal; cl, cleithrum; den, dentary; end, endopterygoid; epl, epipleural rib; fro, frontal; hyo, hyomandibula; lp, lateral process; max, maxilla; met, metapterygoid; na-1, neural arch of first vertebra; ns, neural spine; op, operculum; pas, parasphenoid; pl, pleural rib; pmx, premaxilla; pop, preoperculum; ptt, posttemporal; qua, quadratum; sym, symplectic.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0123056.g004: Anatomical details of †Kenyaichthys.A1–A3 Anatomical details of †K. kipkechi sp. nov. (paratype 1237R(1)´04): A1–A2 Head and pectoral girdle, left lateral view; A3 Caudal fin rays covered with a single scale (arrow), left lateral view; B Head of †K. kipkechi sp. nov. (paratype 1160b´04), right dorsolateral view; C Disarticulated premaxilla and maxilla of †Kenyaichthys cf. kipkechi (1226a(1)´04), right lateral view; D1–D4 Anatomical details of †K. kipkechi (paratype 1209a/b´05): D1 Head and anterior part of body (1192a´05), arrow indicates lateral processes and spine of the first vertebra, left lateral view; D2 Schematic reconstruction of the first vertebra (paratype 1192a/b´05), anterior view; D3 Reconstruction of vertebrae 1–3 with pleural ribs and rod-shaped epipleural ribs (1192b´05), left lateral view; D4 Head and anterior part of body (1192b´05) with epipleural ribs on vertebrae 1–5, left lateral view. Abbreviations: apl, autopalatinum; br, branchiostegal rays; cer, ceratohyal; cl, cleithrum; den, dentary; end, endopterygoid; epl, epipleural rib; fro, frontal; hyo, hyomandibula; lp, lateral process; max, maxilla; met, metapterygoid; na-1, neural arch of first vertebra; ns, neural spine; op, operculum; pas, parasphenoid; pl, pleural rib; pmx, premaxilla; pop, preoperculum; ptt, posttemporal; qua, quadratum; sym, symplectic.
Mentions: Small fishes, ranging in size from 22 to 40 mm total length (TL), and 20 to 36 mm standard length (SL) (see Table 1 and S1 Table for measurements). Most specimens are preserved in lateral view, indicating that the body is elongate and laterally compressed. Body height reaches a maximum between the posterior margin of the head and the origin of the pectoral fin, and ranges from 16–28% of SL. The minimum body height, ranging from 6–12% SL, lies at the middle of the caudal peduncle. Head length ranges from 25–34% SL; the lateral profile from the snout to the occiput is asymmetrical, with a weakly rising long anterior part, and a curving short posterior part (Fig 3). The snout is slightly pointed, with the lower jaw slightly longer than the upper (superior mouth) (see Table 1, S1 Table and Fig 3). The caudal peduncle is long and elongate (22–30% SL), and reveals a slightly concave ventral and dorsal profile (Fig 3A1). The caudal fin ranges in size from 8 to 17% SL and is rounded to truncate (Fig 3A7). Cycloid scales are visible on the whole body and parts of the head (operculum, preoperculum, frontals), but not on the fins, with the exception of a few scales on the caudal fin base (Fig 4A3).

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.


Related in: MedlinePlus