Phylogenomics of pike cichlids (Cichlidae: Crenicichla) of the C. mandelburgeri species complex: rapid ecological speciation in the Iguazú River and high endemism in the Middle Paraná basin

Hydrobiologia - The Crenicichla mandelburgeri species complex from the Middle Paraná basin is a diverse group of cichlid species and contains all known ecomorphs found within the entire genus...     

Teleocichla preta,a new species of cichlid from the Rio Xingu Basin in Brazil (Teleostei: Cichlidae)

Teleocichla preta nov. sp. inhabits the rapids along the Rio Xingu and lower portion of the Rio Iriri. It is the largest species in the genus, reaching 121·3 mm standard length (L_S) while others do not reach more than 87·8 mm L_S. Teleocichla preta is distinguished from all other species of Teleocichla by the unique blackish (in live specimens) or dark brown (preserved specimens) overall colouration of the body, which masks the faint vertical bars or zig‐zag pattern of blotches on the flanks. Teleocichla preta also has a deeper body and a deep laterally compressed caudal peduncle, unlike any other congener, as well as a stout lower pharyngeal tooth plate bearing molariform teeth on its median area.     

Phylogenomics of pike cichlids (Cichlidae: Crenicichla): the rapid ecological speciation of an incipient species flock

The rapid rise of phenotypic and ecological diversity in independent lake‐dwelling groups of cichlids is emblematic of the East African Great Lakes. In this study, we show that similar ecologically based diversification has occurred in pike cichlids (Crenicichla) throughout the Uruguay River drainage of South America. We collected genomic data from nearly 500 ultraconserved element (UCEs) loci and >260 000 base pairs across 33 species, to obtain a phylogenetic hypothesis for the major species groups and to evaluate the relationships and genetic structure among five closely related, endemic, co‐occurring species (the Uruguay River species flock; URSF). Additionally, we evaluated ecological divergence of the URSF based on body and lower pharyngeal jaw (LPJ) shape and gut contents. Across the genus, we recovered novel relationships among the species groups. We found strong support for the monophyly of the URSF; however, relationships among these species remain problematic, likely because of the rapid and recent evolution of this clade. Clustered co‐ancestry analysis recovered most species as well delimited genetic groups. The URSF species exhibit species‐specific body and LPJ shapes associated with specialized trophic roles. Collectively, our results suggest that the URSF consists of incipient species that arose via ecological speciation associated with the exploration of novel trophic roles.     

A new species and geographical variation in the Telmatochromis temporalis complex (Teleostei, Cichlidae) from Lake Tanganyika

Telmatochromis brachygnathus sp.n. is described from the southern and central parts of Lake Tanganyika. It can be distinguished from the similar T. temporalis mainly by its smaller mouth. Morphological distinct populations were found in both species.     

Phylogenetic relationships of species of Crenicichla (Teleostei: Cichlidae) from southern South America based on the mitochondrial cytochrome b gene

Phylogenetic analysis using Bayesian inference, likelihood and parsimony methods was conducted on 60 complete mitochondrial cytochrome b sequences from 21 species of Crenicichla, including all species known from Uruguay (Crenicichla celidochilus, Crenicichla lepidota Crenicichla minuano, Crenicichla missioneira, Crenicichla punctata, Crenicichla scottii, Crenicichla vittata), Crenicichla compressiceps, Crenicichla empheres, Crenicichla geayi, Crenicichla iguassuensis, Crenicichla macrophthalma, Crenicichla menezesi, Crenicichla notophthalmus, Crenicichla regani, Crenicichla cf. regani, Crenicichla semifasciata, Crenicichla sveni, Crenicichla tendybaguassu, two unidentified species, and also two species of Teleocichla. Bayesian analysis resulted in a trichotomy with three major groups: (1) The C. missioneira species group (C. celidochilus, C. empheres, C. minuano, C. missioneira, C. tendybaguassu, and an undescribed species analyzed); (2) a group of southern species (C. iguassuensis, C. punctata, C. scottii, C. vittata); and (3) a rather heterogeneous group comprising the type species C. macrophthalma, members of the Crenicichla reticulata species group (C. geayi, C. semifasciata), members of the Crenicichla wallacii species group (C. compressiceps, C. notophthalmus, C. regani, C. cf. regani), members of the Crenicichla saxatilis species group (C. lepidota, C. menezesi, C. sveni, C. sp.), and two species of Teleocichla. Parsimony jackknifing resulted in a quadritomy with: (1) C. macrophthalma, (2) Teleocichla, (3) the saxatilis + wallacii group species, and (4) the rest, which include C. geayi and C. semifasciata as sister group to a dichotomy with the C. missioneira group and the remaining southern species. The sequence variation within the C. missioneira group is remarkably minor despite considerable morphological differences, supporting the conclusion that it forms an endemic species flock in the Uruguay River basin. Previously proposed species groups within the speciose genus Crenicichla (more than 90 species known) are partly corroborated. However, C. celidochilus was not previously associated with the C. missioneira species group, and C. vittata has not previously been associated with C. scottii, C. iguassuensis, or C. punctata. Crenicichla lepidota, C. sveni, C. menezesi and C. sp. represent the C. saxatilis group. Species of small size, representing the C. wallacii species group and Teleocichla are characterized by very long branches, and the position of Teleocichla differed considerably between the Bayesian and parsimony trees. This finding does not invalidate Teleocichla but rather suggests that the several monophyletic major clades within Crenicichla may need nominal recognition. A putative hybrid specimen with a morphology combining components from C. vittata and C. scottii, but with a cytochrome b sequence from C. scottii was found in a sample from the Rio Quaraí/Cuareim. Another putative hybrid specimen with a unique morphology but a cytochrome b sequence agreeing with C. scottii was found in a sample from Maldonado, but no other Crenicichla species than C. scottii is known from that locality.     

Phylogeny and biogeography of cichlid fishes (Teleostei: Perciformes: Cichlidae)

Family level molecular phylogenetic analyses of cichlid fishes have generally suffered from a limited number of characters and/or poor taxonomic sampling across one or more major geographic assemblage, and therefore have not provided a robust test of early intrafamilial diversification. Herein we use both nuclear and mitochondrial nucleotide characters and direct optimization to reconstruct a phylogeny for cichlid fishes. Representatives of major cichlid lineages across all geographic assemblages are included, as well as nearly twice the number of characters as any prior family‐level study. In a strict consensus of 81 equally most‐parsimonious hypotheses, based on the simultaneous analysis of 2222 aligned nucleotide characters from two mitochondrial and two nuclear genes, four major subfamilial lineages are recovered with strong support. Etroplinae, endemic to Madagascar (Paretroplus) and southern Asia (Etroplus), is recovered as the sister taxon to the remainder of Cichlidae. Although the South Asian cichlids are monophyletic, the Malagasy plus South Asian lineages are not. The remaining Malagasy lineage, Ptychochrominae, is monophyletic and is recovered as the sister group to a clade comprising the African and Neotropical cichlids. The African (Pseudocrenilabrinae) and Neotropical (Cichlinae) lineages are each monophyletic in this reconstruction. The use of multiple molecular markers, from both mitochondrial and nuclear genes, results in a phylogeny that in general exhibits strong support, notably for early diversification events within Cichlidae. Results further indicate that Labroidei is not monophyletic, and that the sister group to Cichlidae may comprise a large and diverse assemblage of percomorph lineages. This hypothesis may at least partly explain why morphological studies that have attempted to place Cichlidae within Percomorpha, or that have tested cichlid monophyly using only “labroid” lineages, have met with only limited success. © The Willi Hennig Society 2004.     

A new Apistogramma species (Teleostei, Cichlidae) from the Rio Negro in Brazil and Venezuela

Apistogramma diplotaenia sp.n. occurs in the upper and middle Rio Negro. The largest among 186 specimens studied is a 29.2 mm SL male, the largest female is 22.9 mm SL. Distinguishing characters include a unique colour pattern, consisting of two dark bands along the side which converge anteriorly and posteriorly. A comparative osteological study, including other species of Apistogramma and the genera Taeniacara and Apistogrammoides , indicates a progressive forwards loss of infraorbital ossicles and foramina among dwarf cichlids. The long, rod-like interarcual cartilage of Apistogramma, Apistogrammoides and Satanoperca possibly represents a plesiomorphic condition otherwise unknown among cichlids.     

Multilocus phylogeny of Crenicichla (Teleostei: Cichlidae), with biogeography of the C. lacustris group: species flocks as a model for sympatric speciation in rivers

First multilocus analysis of the largest Neotropical cichlid genus Crenicichla combining mitochondrial (cytb, ND2, 16S) and nuclear (S7 intron 1) genes and comprising 602 sequences of 169 specimens yields a robust phylogenetic hypothesis. The best marker in the combined analysis is the ND2 gene which contributes throughout the whole range of hierarchical levels in the tree and shows weak effects of saturation at the 3rd codon position. The 16S locus exerts almost no influence on the inferred phylogeny. The nuclear S7 intron 1 resolves mainly deeper nodes. Crenicichla is split into two main clades: (1) Teleocichla, the Crenicichla wallacii group, and the Crenicichla lugubris-Crenicichla saxatilis groups (“the TWLuS clade”); (2) the Crenicichla reticulata group and the Crenicichla lacustris group-Crenicichla macrophthalma (“the RMLa clade”). Our study confirms the monophyly of the C. lacustris species group with very high support. The biogeographic reconstruction of the C. lacustris group using dispersal-vicariance analysis underlines the importance of ancient barriers between the middle and upper Paraná River (the Guaíra Falls) and between the middle and upper Uruguay River (the Moconá Falls). Our phylogeny recovers two endemic species flocks within the C. lacustris group, the Crenicichla missioneira species flock and the herein discovered Crenicichla mandelburgeri species flock from the Uruguay and Paraná/Iguazú Rivers, respectively. We discuss putative sympatric diversification of trophic traits (morphology of jaws and lips, dentition) and propose these species flocks as models for studying sympatric speciation in complex riverine systems. The possible role of hybridization as a mechanism of speciation is mentioned with a recorded example (Crenicichla scottii).     

Comparative ontogenesis and cytomorphology of the nasal organs in some species of cichlid fish (Cichlidae, Teleostei)

This study compares the ontogenesis, morphology and cytology of olfactory organs of several species of Cichlidae (Pisces, Teleostei), from Asia, Africa and America, belonging to the subfamilies Tilapinae and Haplochrominae. Cichlids, in contrast to most other fish families, possess only one naris on each side of the nose that serves as both inlet and outlet opening. The olfactory rosettes are round, 1.8–4.2 mm diameter, and situated directly below the nares. Each rosette consists of a central raphe with attached lamellae whose number increases with age, remains constant in adults and differs in the various species. Onset of organization of the nasal organs from the neuroectoderm begins 14–16 hours after fertilization in bottomspawner cichlids, and 30–53 hours after fertilization in mouthbrooder embryos. A comparative ontogenetic study of embryos and larvae of both ethological types has shown that this difference in timing of morphogenesis also continues in the formation of the nasal pits, the development of the nasal epithelium, and the olfactory nerves. Comparative data are provided for these processes, including LM, TEM and SEM of the stereocilia and kinocilia-bearing cells, as well as of the microvillar cells. The distribution of these cell-types on the olfactory lamellae differs in the various species. The faster development of the nasal organs observed in larvae of bottomspawners as compared to mouthbrooders also matches the development of other vital organs in these two etho-types and seems to be of high adaptive value, providing the bottomspawners at an earlier stage with sensitive organs in the surrounding hostile habitats.     

Description of a new cichlid fish species of the genus Benthochromis (Perciformes: Cichlidae) from Lake Tanganyika

Benthochromis horii , a new cichlid species is described based on 19 type specimens from the deep waters of Lake Tanganyika. It differs from its congeners by having smaller eyes and longer snout (eye length usually shorter than snout length v. equal to or longer than snout length in Benthochromis tricoti and Benthochromis melanoides ), and more dorsal fin rays (total number of spines and soft rays in dorsal fin usually 30 or 31 v. usually 28 or 29 in B. tricoti and B. melanoides ). Large males of the new species differ from those of congeneric species in terms of their body colour pattern and long pelvic fins. This species has been confused with B. tricoti and has been traded as an aquarium fish.     

Phylogeny and species diversity of the genus Herichthys (Teleostei: Cichlidae)

We provide a review of the systematics of Herichthys by evaluating the usefulness of several mitochondrial and nuclear genetic markers together with morphological data. The nDNA next‐generation sequencing ddRAD analysis together with the mtDNA cytochrome b gene provided well‐resolved and well‐supported phylogenies of Herichthys. On the other hand, the nDNA S7 introns have limited resolution and support and the COI barcoding analysis completely failed to recover all but one species of Herichthys as monophyletic. The COI barcoding as currently implemented is thus insufficient to distinguish clearly distinct species in the genus Herichthys that are supported by other molecular markers and by morphological characters. Based on our results, Herichthys is composed of 11 species and includes two main clades (the H. labridens and H. cyanoguttatus species groups). Herichthys bartoni is in many respects the most plesiomorphic species in the genus and has a conflicting phylogenetic position between mtDNA and nDNA markers, where the robust nDNA ddRAD data place it as a rather distant basal member of the H. labridens species group. The mtDNA of H. bartoni is on the other hand only slightly divergent from the sympatric and syntopic H. labridens, and the species thus probably have hybridized in the relatively recent past. The sympatric and syntopic Herichthys steindachneri and H. pame are supported as sister species. The Herichthys cyanoguttatus species group shows two well‐separated basal species (the northernmost H. minckleyi and the southernmost H. deppii) followed by the closely related and centrally distributed species H. cyanoguttatus, H. tepehua, H. carpintis, and H. tamasopoensis whose relationships differ between analyses and show likely hybridizations between themselves and the two basal species as suggested by conflicts between DNA analyses. Several instances of introgressions/hybridizations have also been found between the two main clades of Herichthys.     

Molecular phylogeny and biogeography of the Neotropical cichlid fish tribe Cichlasomatini (Teleostei: Cichlidae: Cichlasomatinae)

We have conducted the first comprehensive molecular phylogeny of the tribe Cichlasomatini including all valid genera as well as important species of questionable generic status. To recover the relationships among cichlasomatine genera and to test their monophyly we analyzed sequences from two mitochondrial (16S rRNA, cytochrome b) and one nuclear marker (first intron of S7 ribosomal gene) totalling 2236 bp. Our data suggest that all genera except Aequidens are monophyletic, but we found important disagreements between the traditional morphological relationships and the phylogeny based on our molecular data. Our analyses support the following conclusions: (a) Aequidens sensu stricto is paraphyletic, including also Cichlasoma (CA clade); (b) Krobia is not closely related to Bujurquina and includes also the Guyanan Aequidens species A. potaroensis and probably A. paloemeuensis (KA clade). (c) Bujurquina and Tahuantinsuyoa are sister groups, closely related to an undescribed genus formed by the 'Aequidens'pulcher-'Aequidens'rivulatus groups (BTA clade). (d) Nannacara (plus Ivanacara) and Cleithracara are found as sister groups (NIC clade). Acaronia is most probably the sister group of the BTA clade, and Laetacara may be the sister group of this clade. Estimation of divergence times suggests that the divergence of Cichlasomatini started around 44Mya with the vicariance between coastal rivers of the Guyanas (KA and NIC clades) and remaining cis-andean South America, followed by evolution of the Acaronia-Laetacara-BTA clade in Western Amazon, and the CA clade in the Eastern Amazon. Vicariant divergence has played importantly in evolution of cichlasomatine genera, with dispersal limited to later range extension of species within genera.     

Structure and development of first-generation teeth in the cichlid Hemichromis bimaculatus (Teleostei, Cichlidae)

In order to build a reference system to assess results of ongoing in vitro experiments on the study of epithelial-mesenchymal interactions during odontogenesis in actinopterygians, we have chosen to study the first-generation teeth of the cichlid Hemichromis bimaculatus from initiation until attachment both at the light and transmission electron microscopical level. Although their development follows the general pattern of teleost tooth formation, first-generation teeth show peculiarities compared with later tooth generations, including their size, bare emergence from the epithelium, absence of dentinal tubules and of nerves and capillaries in the pulp cavity, and organization of the outer dental epithelium. Four developmental stages (a to d) prior to attachment (stage e) have been distinguished. The oral epithelium invaginates into the underlying mesenchyme (stage a) and is later folded to form a bell-shaped dental organ (stage b) without any primordial thickening, or any other morphological indication of imminent invagination. Then, the collagenous enameloid matrix is laid down, most probably by the odontoblasts (early stage c), soon followed by predentine deposition and the beginning of enameloid mineralization (late stage c). With ongoing dentinogenesis, the enameloid matrix matures (stage d), i.e. the organic constituents are removed and the matrix further mineralizes. Finally (stage e), an annular collar of attachment bone is deposited to fix the tooth onto the underlying bone.     

A new Aequidens species from the Rio Trombetas, Brasil, and redescription of Aequidens pallidus (Teleostei, Cichlidae)

Aequidens pallidus (Heckel) reaches c. 140 mm standard length and occurs in the drainages of the blackwater rivers Negro, Puraquequara, Preto da Eva and Uatumã in Brasil. Aequidens duopunctata Haseman is a junior synonym. Aequidens tubicen sp.n., was collected in the Trombelas and Mapuera rivers a little upstream of Cachoeira Porteira. The largest specimen is 116 mm standard length. It differs from all other Aequidens species in the possession of a dark spot at the inner angle of the preopercle and adjacent cheek. Aequidens pallidus and A. tubicen form a group diagnosed by a high number of vertebrae (14 + 13 = 27) and three colour pattern synapomorphies: lateral band positioned more dorsally and the midlateral spot positioned more posteriorly than in other Aequidens species, and caudal spot preceded by a large light spot at the dorsal margin of the caudal peduncle.     

Description of a new Acaronia species (Teleostei, Cichlidae) from the Rio Orinoco and Rio Negro drainages

Acaronia vultuosa sp.n. occurs in the Rio Orinoco and upper Rio Negro drainages. In the Rio Negro it overlaps slightly the range of its only congener, A. nassa (Heckel), from which it can be distinguished by (1) the lack of microbranchiospines on the first gill arch, (2) thc separate instead of coalesced anterior gill rakers on the first gill arch, and (3) the colour pattern, which includes a much larger midlateral blotch and a different pattern of dark markings on the head.     

Cytological and morphological ontogenesis and involution of the thymus in cichlid fishes (Cichlidae,Teleostei)

The ontogenesis and involution of thymus in cichlid fishes was studied with the aim of comparing development in the bottom-spawning species Tilapia zillii and T. tholloni, and in the mouth-brooding species Oreochromis auratus, O. niloticus, O. mossambicus, and Sarotherodon galilaeus. For comparison, data are also given on bottom-spawning Cichlasoma spp. from America and mouth-brooding Pseudotropheus auratus and Aulonocara nyassae from Africa. Developmental changes were followed histologically by means of light and electron microscopy of sections, beginning with embryos 24 h after fertilization, up to 14-year-old specimens of O. auratus. In all these fish, the anlagen of the thymus glands begins from the third and fourth gill pouches, and their development shows a high correlation with the pace of general organogenesis, which differs greatly in the bottom-spawning and mouth-brooding cichlids. In juveniles of bottom-spawners of 20–40 mm total length and in mouth-brooders of 40–60 mm total length, three cell types are present in the thymus: thymocytes, with large, dense nuclei; epitheliocytes, with long cell extensions containing bundles of tonofibrils; and reticulocytes, with short, granulated cell extensions. Hassall's corpuscles start to develop in larvae of T. zillii at 20–35 mm total length, and in specimens of 40 mm and more total length the corpuscles are typical, formed by inner and outer rings of epitheliocytes. At 30–45 mm total length, cell debris starts to accumulate in the interior of the corpuscles as an early sign of regression. As involution continues, macrophages accummulate within and around the Hassall's corpuscles. The epitheliocyte rings are eventually completely broken down. Isles of thymocytes persist in tilapias from the age of 1–14 years, but most of the thymus volume is occupied by blood lacunae and pigmented macrophage aggregations. The morphology is similar in the mouth-brooding species Pseudotropheus beginning at 1.5 years of age. © 1995 Wiley-Liss, Inc.     

A new species of Petrochromis (Perciformes: Cichlidae) from Lake Tanganyika

Based on morphological and molecular analyses of a Petrochromis fish (Cichlidae) from the southern end of Lake Tanganyika, this fish is considered a taxonomic species distinct from the six known congeners. A new scientific name is proposed for this fish. A key to the seven Petrochromis species is included.     

Microdontochromis rotundiventralis, a new cichlid fish (perciformes: Cichlidae) from Lake Tanganyika

Microdontochromis rotundiventralis, a new species of cichlid fish, is described on the basis of 13 specimens from Nkumbula Island, Lake Tanganyika (Zambia). It is distinct from its only congener,M. tenuidentatus, in having two (rarely one) rows of teeth on both jaws, a rounded distal margin on the pelvic fin, the outermost pelvic fin soft ray length 1.23–1.43 times the innermost ray, a deeper body (depth 26.8–29.1% standard length) and the anal fin with 9 (rarely 8 or 10) soft rays.     

A revision of the genus Labidochromis (Teleostei: Cichlidae) from Lake Malawi

The diagnosis of the genus Labidochromis is revised to include species with bicuspid outer teeth. Sixteen species, of which 13 are new, are described and illustrated and the validity of five others is discussed. The interrelationships between members of the genus and the relationship of the genus to other genera are discussed. No clearly defined sister group to the genus has been found either within or outside the Lake Malawi cichlid species flock. A key based on the coloration of known species is included.