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PubMedDate not supplied

[New species of Ilyodon (Cyprinodontiformes: Goodeidae) from de Balsas river basin, Mexico].

A new species of the fish genus Ilyodon is described from San Juan Tacámbaro river, Michoacán, México 19 degrees 10' 42" N, 101 degrees 20' 45" W. We used 129 specimens representing I. whitei, 60 of I. furcidens and 84 of the new species for our analyses. These included samples of both sexes. The new species is distinguished from I. whitei and I. furcidens by its strongly convex cephalic profile, the size and disposition of the pores of the lateral line of the preorbital, the thinner caudal peduncle, its strongly bifid tooth and the form and size of neural prezygapophyses of caudal vertebrae.

Animals↗
PubMed2001

Impacts of Oreochromis mossambicus (Perciformes: Cichlidae) upon habitat segregation among cyprinodontids (Cyprinodontiformes) of a species flock in Mexico.

Five species of Cyprinodon in Laguna Chichancanab, Yucatan, Mexico comprise a young species flock whose ecology and evolution has not been thoroughly studied, but whose existence is threatened with extinction. Species flocks evolve in isolated areas where predators and competitors are absent. Since the description of the Chichancanab flock, Oreochromis mossambicus, a species introduced into the lake for which I examined habitat in the 1980's, has become common throughout the basin. I assessed relative abundance of flock species in the lake. examined habitat use and segregation among the three most common flock species and examined the affects of O. mossambicus upon flock species habitat use. Cyprinodon beltrani was the most abundant flock species in 1997, followed by C. maya and C. labiosus; C. verecundus and C. simus were rare. Cyprinodon beltrani was found in shallow water, nearshore, over thick beds of submerged Chara, and little emergent vegetation. Cyprinodon beltrani exhibited diurnal variation in nearshore habitat use. In the field, the habitat use of C. beltrani and O. mossambicus broadly overlapped. In aquarium experiments, three flock species exhibited habitat use segregation and C. beltrani and C. labiosus showed agonistic behaviors that strengthened segregation. Cyprinodon maya differed from C. beltrani and C. labiosus by its greater dispersion of individuals and use of areas higher in the water column. The presence of O. mossambicus caused a shift in habitat use by C. maya and C. labiosus that put these species into habitat occupied by C. beltrani. The presence of introduced species has caused a significant perturbation of the conditions that fomented speciation of the Chichancanab flock 8,000 years ago.

Agonistic Behavior↗
PubMedDate not supplied

[Ingestion of Culex quinquefasciatus larvae (Diptera: Culicidae) by Girardinus metallicus (Cyprinodontiformes: Poecilidae)].

Data on ingestion of Culex quinquefasciatus Say 1823 larvae by Girardinus metallicus, Poey 1854 under lab and field conditions were obtained and compared to those reported on the same species by other authors. It was observed that G. metallicus is not so aggressive as other species of larvivorus fish in capturing larvae. The consumption of larvae is higher in females since males prefer feeding on vegetation. Because of the bioecological characteristics of the species, resistance to management and survival in cultural conditions, G. metallicus is recommended to be used as bioregulator of mosquito larvae.

Animals↗
PubMedDate not supplied

[Embryonic development of Rivulus cylindraceus. (Cyprinodontiformes: Cyprinodontidae): biocontrol agent for mosquitoes].

A description is made of the ecomorphological development of Rivulus cylindraceus in laboratory conditions. The habitat of this larvivorous fish is the brackish waters in channels near the coast. As a peculiar characteristic, gastrulation takes place after the vitelline cover is completely closed. Approximately 120 hours later, a sharp decrease in heart rate takes place as a possible adaptation to the environmental conditions.

Animals↗
PubMedDate not supplied

[Feeding of the young of the larvivorous fish Poecilia reticulata (Cyprinodontiformes: Poeciliidae) in a natural breeding site of Culex quinquefasciatus (Say, 1823)].

The objective of this study is to determine the feeding patterns of the young of the larvivorous fish Poecilia reticulata in a natural breeding site of Culex quinquefasciatus. The experimental material were the young of this species, caught in two back water sites of Quibu river with different larval density. Dissection of the young, fixed in 4% formal, was carried out for the analysis of stomach contents. The results show that at an early age the young of Poecilia reticulata are already effective bioregulators of the larvae of these mosquitoes of medical and veterinary importance.

Animals↗
PubMed1993

CD15 in trophotaeniae of the viviparous goodeid fish Xenotoca eiseni (Cyprinodontiformes, Teleostei).

The antigen CD15, also known as 3-fucosyl-N-acetyl-lactosamine (FAL), or Stage Specific Embryonic Antigen (SSEA-1) is a cell membrane and cytoplasmic antigen, that is present in several mammalian tissues. Using immunohistochemistry the monoclonal antibodies 3B9 and B4,3 detected CD15 in whole mount preparations of trophotaeniae of embryos of the matotroph viviparous teleost Xenotoca eiseni. A specific localization is encountered in the ecto- and entodermal portion of the trophotaenial epithelium. A positive reaction in the fibrocytes of the inner mesenchymal core of trophotaeniae is doubtful since a relative high background is present in these cells. CD15 positivity has been observed in all developmental stages studied. The exact role of CD15 is unclear. An involvement in endocytic activity is postulated.

Animals↗
PubMed1998

A new species of Rhabdochona Railliet, 1916 (Nematoda: Rhabdochonidae) from endemic goodeids (Cyprinodontiformes) from two Mexican lakes.

A new species of Rhabdochona from 2 species of freshwater fishes, Alloophorus robustus and Goodea atripinnis, is described from 2 lakes of the Mesa Central of Mexico. Rhabdochona lichtenfelsi n. sp. belongs to a group of species possessing inconspicuous bifurcated deirids and a prostom armed with 10 large teeth. It is distinguished from them because the left spicule is shorter, the tip is bifurcate, and both spicules lack a reflected dorsal barb. The new species most closely resembles Rhabdochona catostomi and Rhabdochona milleri but differs from them because the former possesses a left spicule tip with ventral barb, right spicule with reflected distal barb, and 5 pairs of postanal papillae, whereas R. milleri has 14 prostomal teeth, eggs rounded, and left spicule with slightly outlined bifurcation and right with a dorsal barb. Previous records of R. milleri in Mexico must be referred to R. lichtenfelsi.

Animals↗
PubMed2003

Regional variations in the outer retina of atherinomorpha (Beloniformes, Atheriniformes, Cyprinodontiformes: Teleostei): photoreceptors, cone patterns, and cone densities.

The outer retinae of adults of 13 atherinomorph species, representing nine different families, were examined by both light and electron microscopy. The retinae were investigated with respect to photoreceptor types, cone densities, and cone patterns. All data were composed to eye maps. This procedure allows an interspecific comparison of the regional differences within the outer retina among these shallow-water fish. Furthermore, for a more detailed pattern analysis nitro-blue tetrazolium chloride- (NBT)-stainings in the retina of Melanotaenia maccullochi are presented. Apart from rods, eight morphologically different cone types could be identified: short, intermediate, and long single cones, double cones (equal and unequal), triple cones (triangular and linear), and in Ameca splendens one quadruple cone. Dimensions and occurrence of photoreceptors vary among the respective species and within the retinal regions. In the light-adapted state, the cones are arranged in highly ordered mosaics. Five different cone tessellation types were found: row patterns, twisted row patterns, square patterns, pentagonal patterns, and, exclusively in Belone belone, a hexagonal pattern. In Melanotaenia maccullochi the different spectral photoreceptor classes correspond well with the distribution of morphological photoreceptor classes within the mosaic. Double cone density maxima together with a highly ordered cone arrangement usually occur in the nasal and/or ventral to ventrotemporal retina. In most of the species that were examined these high-density regions are presumed to process visual stimuli from the assumed main directions of vision, which mainly depend on feeding behavior and predator pressure. Our findings are discussed with respect to the variable behavioral and visual ecology and phylogeny of the respective species.

Animals↗
PubMed1999

Molecular phylogeny of the live-bearing fish genus Poecilia (Cyprinodontiformes: Poeciliidae).

Members of the genus Poecilia exhibit extensive morphological, behavioral, and life history variation within and between species. This natural variation, coupled with short generation times and the ease with which members of this genus can be cultured in the lab, have made several species model systems for studying the effects of sexual and natural selection on the evolution of natural populations. Given that there is no clear understanding of the phylogenetic relationships within the genus, these studies have not been put into a historical context, and between-species comparisons have been limited. We sequenced the complete NADH Dehydrogenase Subunit 2 (ND2) mitochondrial gene (1047 bp) in representatives of the major divisions of the genus in order to examine these relationships. The subgeneric groups of Rosen and Bailey (1963) are, for the most part, supported, with some adjustment within the subgenera Poecilia and Pamphorichthys. The morphological distinctness of the groups within Poecilia suggest that the original generic designations be reinstated, but this awaits a more thorough analysis. Two implications from the phylogeny are particularly relevant to sexual selection studies: within the North and Central American mollies, the three species of sailfin mollies form a monophyletic group, and within the subgenus Lebistes, the sister taxon to the guppy, P. reticulata, is most likely the group of species previously designated as Micropoecilia.

Animals↗
PubMed1999

Phylogeny of the Neotropical killifish family Rivulidae (Cyprinodontiformes, Aplocheiloidei) inferred from mitochondrial DNA sequences.

Phylogenetic relationships of 70 taxa representing 68 species of the Neotropical killifish family Rivulidae were derived from analysis of 1516 nucleotides sampled from four different segments of the mitochondrial genome: 12S rRNA, 16S rRNA, cytochrome oxidase I, and cytochrome b. The basal bifurcation of Cynolebiatinae and Rivulinae (Costa, 1990a,b) is supported; however, Terranatos, Maratecoara, and Plesiolebias are rivulins, not cynolebiatins. These three genera, along with the other recognized annual rivulin genera, form a monophyletic clade. Austrofundulus, Rachovia, Renova, Terranatos, and 3 species of the genus Pterolebias, all from northeastern South America, form a monophyletic clade excluding other species of Pterolebias. Pterolebias as presently understood is clearly polyphyletic. Trigonectes and Moema are supported as sister groups but do not form a monophyletic group with the genera Neofundulus and Renova as previously proposed. The suite of adaptations necessary for an annual life history has clearly been lost several times in the course of rivulid evolution. Also revealed is a considerable increase in substitution rate in most annual lineages relative to the nonannual Rivulus species. The widespread and speciose genus Rivulus is paraphyletic, representing both basal and terminal clades within the Rivulidae. Previous hypotheses regarding the vicariant origin of Greater Antillean Rivulus species are supported. Most rivulid clades show considerable endemism; thus, detailed analysis of rivulid phylogeny and distribution will contribute robust hypotheses to the clarification of Neotropical biogeography.

Amino Acid Sequence↗