Research Article |
Corresponding author: Pedro H.N. Bragança ( pedrobra88@gmail.com ) Academic editor: Peter Bartsch
© 2018 Pedro H.N. Bragança, Pedro F. Amorim, Wilson J.E.M. Costa.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Bragança PHN, Amorim PF, Costa WJEM (2018) Pantanodontidae (Teleostei, Cyprinodontiformes), the sister group to all other cyprinodontoid killifishes as inferred by molecular data. Zoosystematics and Evolution 94(1): 137-145. https://doi.org/10.3897/zse.94.22173
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Pantanodon, containing two African extant species and four European fossil species, for a long time had an uncertain position among the Cyprinodontiformes due to its peculiar morphology. In the last decades, Pantanodon has been considered closely related to African lamp-eyes of the Procatopodinae clade, which is contained in the Poeciliidae, a teleost fish family with a broad geographical distribution in Africa and the Americas. However, recent molecular studies have challenged the monophyly of the Poeciliidae, but the position of Pantanodon remained uncertain. We analysed one mitochondrial (COI) and five nuclear loci (GLYT1, MYH6, SH3PX3, RAG1, ENC1), a total of 5,083 bp, for 27 cyprinodontiform taxa and 6 outgroups, obtaining a well-supported phylogeny, in which the monophyly of Poeciliidae, as supported by morphological data is refuted. Pantanodon stuhlmanni, the type species of the genus, is recovered as the most basal cyprinodontoid lineage and other African taxa formerly placed in Poeciliidae are highly supported as more closely related to European non-poeciliid cyprinodontoid genera than to other taxa. Since the present tree topology is not compatible with the present classification of the Cyprinodontoidei, a new classification using available family group names is provided: Pantanodontidae is used for Pantanodon; Procatopodidae, for the African lamp-eye clade; and Fluviphylacidae, for the South American genus Fluviphylax. Poeciliidae is restricted to the American livebearers, hence restoring the classification generally used prior to 1981.
Phylogeny, Molecular Systematics, Classification, Fluviphylacidae , Poeciliidae , Procatopodidae
The teleost order Cyprinodontiformes is a diverse group of small fishes living in freshwater and estuarine environments of all continents, except Oceania and Antarctica. Many of them are popular aquarium fishes, but some species such as guppies and mangrove killifishes are among the most important experimental species used as model organisms for a large spectrum of scientific areas. However, cyprinodontiform classification is still not well established despite continuous efforts to understanding their phylogenetic relationships (e.g.
Prior to
In the cyprinodontiform classification provided by
Recently, some molecular phylogenetic analyses (
In order of to test the phylogenetic position of Pantanodon and search for a more stable classification, the present study includes a larger gene sample, comprising one mitochondrial and five nuclear genes for representatives of all cyprinodontiform families. A comparative analysis of extant and fossil species of Pantanodon provides an updated diagnosis for the genus.
Twenty species of Cyprinodontoidei, representing all the main lineages as previously described in morphological (
Osteological studies were made on cleared and stained specimens (c&s) prepared according to
The genomic DNA was extract from muscle tissue of the right side of the caudal peduncle using DNeasy Blood & Tissue Kit (Qiagen) according to the manufacturer instructions. To amplify the fragments of DNA were used the primers Glyt_F559 and Glyt_R1562, for the Glycosyltransferase gene (GLYT1), myh6_F507 and myh6_R1325, for the cardiac protein encoding gene, Myosin heavy chain 6 (MYH6), SH3PX3_F461, SH3PX3_R1303, SH3PX3_F532 and SH3PX3_R1299, for the SH3 and PX domain-containing 3-like protein (SH3PX3) (
For each gene and codon position Measure Substitution Saturation tests were performed according to the model proposed by
The dataset was partitioned according to each gene. The best-fit evolutionary model was calculated for each partition using the Akaike Information Criterion (AIC) determined by the jModelTest 2.1.7 (
The ML analysis (Fig.
Phylogenetic relationship tree generated by a Maximum Likelihood Analysis of molecular data (5,083 bp, comprising segments of the nuclear genes ENC1, GLYT, MYH6, SH3PX3 and RAG1 and the mitochondrial gene COI). Clade names follows the classification herein proposed. Numbers on each node are bootstrap percentages of the Maximum Likelihood analysis and posterior probabilities of the Bayesian Inference analysis; asterisks indicate maximum values (100 or 1.00 respectively) and a dash refers to values under 50 or 0.50 respectively.
The present analysis is consistent with previous morphological and molecular studies in supporting the monophyly of the Cyprinodontiformes, which contains two well established clades, the suborders Aplocheiloidei and Cyprinodontoidei (
Jaws, jaw suspensorium, opercular apparatus, superficial dermal bones and caudal fin skeleton of Pantanodon stuhlmanni and pelvic fin of P. madagascariensis: A: left jaws, jaw suspensorium and opercular apparatus, lateral view; B, left nasal, dorsal view; C, left lachrymal, lateral view; D, caudal fin skeleton, left lateral view; E: pelvic fin bone and rays. Abbreviations: de, dentary; ep, epural; hp, hypural plate; hy, hyomandibula; io, interopercle; ms, mesopterygoid; pb, pelvic bone; ph, parahypural; pl, palatine; pm, premaxila; po, preopercle; qu, quadrate; r, rays; ra, retroarticular; so, subopercle; sy, sympletic; u2–u4, preural centra 2–4. Scale bar = 1mm. Figure
Branchial arches of Pantanodon stuhlmanni: A, left branchial arches, ventral view of dorsal portion; B, third pharyngobranchial tooth, frontal view; C, left hyoid bar, lateral view; D, fifth ceratobranchial tooth, frontal view; E, left and middle branchial arches, dorsal view of ventral portion. Abbreviations: ach, anterior ceratohyal; b1–2, basibranchials 1–2; bh, basihyal; br, branchiostegal rays; c, ceratobranchials; e4,fourth epibranchial; ih, interhyal; p2-3, pharyngobranchials 2 and 3, pch, posterior ceratohyal; vhh, ventral hypohyal. Scale bar = 1mm. Figure
Our analysis highly supports the monophyly of the group ecompassing all African lamp-eyes species, corroborating previous morphological studies (
The present tree topology indicates relationships not compatible with the current classification of the Cyprinodontoidei. Two families, Cyprinodontidae and Poeciliidae, proposed by
The genus Pantanodon until recently comprised only two extant species, P. stuhlmanni, from brackish water environments of coastal river drainages in Kenya and Tanzania, and P. madagascariensis from freshwater environments of forested areas in northern Madagascar drainages (e.g.
We are grateful to F. Milvertz and B. Nagy for donating specimens of P. stuhlmanni and providing pictures of P. stuhlmanni, to R. Bayer for donating African lamp-eye specimens and to P. Bartsch, G. Clément, B. Ekrt, W. Fink, Z. Gabsi, Z. Johanson, C. Lamour, J. Maclaine, D. Nelson, M. Parrent, P. Pruvost, M. Richter, J. Snoeks, M. Veran, E. Vreven, and F. Witzmann, for hospitality during visits to their institutions. We are also grateful to J.L. Mattos for help during molecular analyses and to reviwers J. Snoeks and L. Machado for improving the manuscript with corrections and suggestions during the review process. Part of this study was conducted by PHNB and WJEMC during a long-term stay at
List of species, localities and respective Genbank accession numbers
Data type: Microsoft Excel Worksheet (.xls) file
Material examined
Data type: Microsoft Word Document (.docx) file
Maximum Likelihood (A) and Bayesian Inference (B) analysis including the 16S gene.
Data type: TIF File (.tif) file
Explanation note: Maximum Likelihood (A) and Bayesian Inference (B) analysis including segments of the nuclear genes ENC1, GLYT, MYH6, SH3PX3, RAG1, the mitochondrial genes 16S and first and second codon position of the COI. In ML, bootstrap values under 50 are not represented, and posterior probability values under 0.5 are not represented in BI.
Substitution models according to JModeltest 2.1.7
Data type: Microsoft Excel Worksheet (.xlsx) file
Bayesian Inference tree
Data type: TIF File (.tif) file
Explanation note: Bayesian inference tree comprising segments of the nuclear genes ENC1, GLYT, MYH6, SH3PX3, RAG1 and first and second codon position of the mitochondrial gene COI (5,083 bp). Numbers on each node are posterior probablity values; values under 50 are not present in the tree.