ABSTRACT A morphological revision is presented here on the cohort Otomorpha, a clade currently interpreted as the most primitive among the large supercohort Clupeocephala. Otomorpha is a ...morphologically heterogeneous group represented by clupei forms , alepocephaliforms, and ostariophysans (gonorynchiforms, cypriniforms, characiforms, siluriforms, and gymnoti forms) that inhabit various marine and freshwater environments worldwide. Otomorphs have a long (ca. 145 Ma) and diverse fossil record. They are the largest fish teleostean clade worldwide, as well as the largest of the Neotropical Region. While molecular studies strongly confirm the monophyly of Otomorpha, most potential morphological synapomorphies of the group become homoplastic largely due to the peculiar morphological character states (either losses or transformations) present in alepocephaliforms. The fusion of haemal arches with their respective vertebral centra anterior to preural centrum 2 stands as an unambiguous synapomorphy of the clade. The ankylosis or fusion of the extrascapular and parietal bones, and silvery areas associated with the gas bladder are also interpreted as synapomorphies, although they are homoplastic characters mainly due to secondary losses or further transformations of the morphological features in the alepocephaliforms.
RESUMEN Se realizó una revisión morfológica de la cohorte Otomorpha la que se interpreta como el grupo más primitivo dentro de la gran supercohorte Clupeocephala. Otomorpha incluye peces con una gran diversidad corporal la que está representada por clupeiformes, alopocefáliformes y ostariofisos (gonorinchiformes, cipriniformes, caraciformes, siluriformes y gimnotiformes), los que habitan diversos ambientes marinos y de aguas continentales del planeta. Otomorfos son el grupo de peces más grande a nivel mundial y al mismo tiempo, el más grande de la Región Neotropical. Mientras estudios moleculares confirman la monofilia de Otomorfa, la mayoría de las sinapomorfías morfológicas del grupo se interpretan como homoplásticas debido fundamentalmente a la naturaleza peculiar de ciertos caracteres morfológicos (ya sea pérdidas o transformación de estados de caracteres) de alepocefaliformes. La fusión de los arcos hemales con sus respectivos centros vertebrales anterior al centro preural 2 es una sinapomorfía de la cohorte. La anquilosis o fusión de los huesos extrascapular y parietal y la presencia de áreas plateadas asociadas con la vejiga natatoria son interpretados como sinapomorfías, independientemente de que son caracteres homoplásticos debido a pérdidas o transformaciones de tales caracteres en los alepocefáliformes.
Fish classifications, as those of most other taxonomic groups, are being transformed drastically as new molecular phylogenies provide support for natural groups that were unanticipated by previous ...studies. A brief review of the main criteria used by ichthyologists to define their classifications during the last 50 years, however, reveals slow progress towards using an explicit phylogenetic framework. Instead, the trend has been to rely, in varying degrees, on deep-rooted anatomical concepts and authority, often mixing taxa with explicit phylogenetic support with arbitrary groupings. Two leading sources in ichthyology frequently used for fish classifications (JS Nelson's volumes of Fishes of the World and W. Eschmeyer's Catalog of Fishes) fail to adopt a global phylogenetic framework despite much recent progress made towards the resolution of the fish Tree of Life. The first explicit phylogenetic classification of bony fishes was published in 2013, based on a comprehensive molecular phylogeny ( www.deepfin.org ). We here update the first version of that classification by incorporating the most recent phylogenetic results.
The updated classification presented here is based on phylogenies inferred using molecular and genomic data for nearly 2000 fishes. A total of 72 orders (and 79 suborders) are recognized in this version, compared with 66 orders in version 1. The phylogeny resolves placement of 410 families, or ~80% of the total of 514 families of bony fishes currently recognized. The ordinal status of 30 percomorph families included in this study, however, remains uncertain (incertae sedis in the series Carangaria, Ovalentaria, or Eupercaria). Comments to support taxonomic decisions and comparisons with conflicting taxonomic groups proposed by others are presented. We also highlight cases were morphological support exist for the groups being classified.
This version of the phylogenetic classification of bony fishes is substantially improved, providing resolution for more taxa than previous versions, based on more densely sampled phylogenetic trees. The classification presented in this study represents, unlike any other, the most up-to-date hypothesis of the Tree of Life of fishes.
A new species (
Marcopoloichthys mirigioliensis
) of the stem teleosteomorph genus
Marcopoloichthys
is described from the lower Besano Formation (late Anisian at Monte San Giorgio, southern ...Switzerland), making this new species distinct from
Marcopoloichthys furreri
from the Prosanto Formation (early Ladinian at Ducanfurgga, southeastern Switzerland).
Marcopoloichthys mirigioliensis
n. sp. is smaller (ca. 32 mm standard length) than
M. furreri
(ca. 40 mm standard length), and in addition, the two species have some important differences in the caudal endoskeleton and fin, e.g., number of epaxial and hypaxial basal fulcra, uroneural structure, size of hypurals, and presence versus absence of urodermals.
Marcopoloichthys mirigioliensis
n. sp. is the smallest member of Marcopoloichthyidae which is currently known from at least five species living in the Triassic of China (one species), Italy (two and others that remain undescribed), and Switzerland and according to current information, with its ca. 32 mm standard length is candidate to be considered a miniature fish. Additionally, this size makes it the smallest known stem teleost. As in other marcopoloichthyids, the buccal and suspensorium anatomy of
M. mirigiolensis
n. sp. corresponds to that of suction-feeder fishes.
The Albian Muhi Quarry of Central Mexico has produced a variety of fishes, among which the teleosts are the most diversified, including representatives of stem groups together with a variety of crown ...groups. A new genus and species, †Xeneichthys yanesi, is described based on a unique combination of characters, such as a dorsoventral elongation and narrowing of infraorbitals 2 and 3, preopercle, opercle, and cleithrum; absence of some bones, such as the infraorbital 5, interopercle, and pelvic plate and fin; presence of an elongated urostyle and a membranous outgrowth or stegural on the first uroneural; and cycloid and ctenoid scales on the flanks. Due to its combination of characters, †Xeneichthys yanesi is interpreted as belonging to a new extinct family, †Xeneichthyidae, which is considered as an Euteleostei or Euteleosteomorpha incertae sedis. The fish faunas of another Albian quarry, Tlayúa of Tepexi de Rodriguez, Puebla, and Muhi Quarry are compared, and although both contain taxa that can be assigned to stem teleosts (e.g., †ichthyodectiforms and †crossognathiforms), both also contain crown teleosts (e.g., elopomorphs, clupeomorphs, and euteleosts)—all of which are endemic to their respective quarries and make them important centers of diversification of fish faunas during the Early Cretaceous.
This study presents the first comprehensive revision of ‘pholidophoriform’ fishes, which are a key taxon for understanding the early diversification of teleost fish. Systematic revisions of Triassic ...pholidophorids, which are based on numerous well-preserved specimens, include †Annaichthys, gen. et sp. nov., †Knerichthys, gen. nov., †Parapholidophorus, †Pholidoctenus, †Pholidophoretes, †Pholidophorus, †Pholidorhynchodon, and †Zambellichthys, gen. et sp. nov. The morphological descriptions presented support a phylogenetic analysis that proposes a new hypothesis for character evolution within basal Teleostei, with implications for holosteans and teleosteans. The phylogenetic analysis resolves traditional ‘pholidophoriform’ species as a paraphyletic assemblage, with some grouped in a monophyletic †Pholidophoridae and others more closely related to crown-group teleosts. The monophyletic Family †Pholidophoridae is restricted to European Triassic taxa and is the sister group of the Jurassic genus †Eurycormus plus all other teleosts. The latter clade is supported by several synapomorphies, such as an elongate posteroventral process of the quadrate, long epineural processes, and seven or more ural neural arches modified as uroneurals. †Pholidophorus bechei is removed from †Pholidophoridae and recognized as the new genus †Dorsetichthys. Current evidence indicates that the Upper Triassic †Pholidophoretes salvus and †Knerichthys bronni represent the oldest known pholidophorids, and †Prohalecites from the Middle/Upper Triassic boundary represents the oldest stem teleost. Aspidorhynchiforms, pachycormiforms, and †Prohalecites are resolved as stem teleosts. The monophyly of Teleostei, which now includes Triassic pholidophorids, is supported by numerous synapomorphies, such as one suborbital, two supramaxillae, and the articular fused to the angular and retroarticular bones—with further transformations within more advanced teleosts. Synapomorphies of Teleosteomorpha, the clade including crown-group teleosts and all fish more closely related to them than to their closest extant relatives, include the autosphenotic lacking a dermal component, an unpaired vomer, and one long, toothed, serrated appendage on the cleithrum.
The tree of life of fishes is in a state of flux because we still lack a comprehensive phylogeny that includes all major groups. The situation is most critical for a large clade of spiny-finned ...fishes, traditionally referred to as percomorphs, whose uncertain relationships have plagued ichthyologists for over a century. Most of what we know about the higher-level relationships among fish lineages has been based on morphology, but rapid influx of molecular studies is changing many established systematic concepts. We report a comprehensive molecular phylogeny for bony fishes that includes representatives of all major lineages. DNA sequence data for 21 molecular markers (one mitochondrial and 20 nuclear genes) were collected for 1410 bony fish taxa, plus four tetrapod species and two chondrichthyan outgroups (total 1416 terminals). Bony fish diversity is represented by 1093 genera, 369 families, and all traditionally recognized orders. The maximum likelihood tree provides unprecedented resolution and high bootstrap support for most backbone nodes, defining for the first time a global phylogeny of fishes. The general structure of the tree is in agreement with expectations from previous morphological and molecular studies, but significant new clades arise. Most interestingly, the high degree of uncertainty among percomorphs is now resolved into nine well-supported supraordinal groups. The order Perciformes, considered by many a polyphyletic taxonomic waste basket, is defined for the first time as a monophyletic group in the global phylogeny. A new classification that reflects our phylogenetic hypothesis is proposed to facilitate communication about the newly found structure of the tree of life of fishes. Finally, the molecular phylogeny is calibrated using 60 fossil constraints to produce a comprehensive time tree. The new time-calibrated phylogeny will provide the basis for and stimulate new comparative studies to better understand the evolution of the amazing diversity of fishes.
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