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PROCEEDINGS OF THE DESERT FISHES COUNCIL
<br />WINSBOROUGH, B.M. Winsbomugh Consulting, Austin, TX
<br />1993 - VOLUME XXV
<br />Ecological aspects of stromatolites and related biogenic structures
<br />in lakes and streams of the Cuatro Cienegas basin, Coahuila, Mexico
<br />Aspectos ecolbgicos de estromatolitos y estructuras biogenicas relacionadas,
<br />en Lagos y arroyos de la Cuenca Cuatro Cienegas, Coahuila, Mexico
<br />KEYWORDS: Cuatro Cienegas; Coahuila; Mexico; stromatolites; algae; diatoms; cyanobacteria; microbial mats; travertines
<br />CLAVES: Cuatro Cienegas; Coahuila; Mexico; Estromatolitos; Algas; Diatomeas; cyanobacterias; caps microbiana
<br />ABSTRACT
<br />Within the lakes and streams of the Cuatro Cienegas Basin, four types of fresh-water stromatolites and
<br />associated carbonate structures are distinguished: 1) laminated stromatolites and oncoids produced by Homoeothrix
<br />balearica and Schizothrix lacustris, with a surface pattern of small, horizontal lobate ledges or micro-terraces; 2)
<br />stony, intricate stromatolites and oncoids constructed by Gongrosira calcifera, cyanobacteria and diatoms; 3) laree,
<br />globose non-laminated stromatolites with a sinuously-incised surface pattern resulting from the growth of Dihhothrix
<br />bonetiana, Schizothrix lacustris, Cvanostylon sp., and diatoms; and 4) laminated, domed stromatolites built by the
<br />sequential growth of Scytonema mirabile, Schizothrix afftnis, and diatoms. These stromatolites and related microbial
<br />deposits associated with them such as microbial mats and travertines, are the principal substrates and sources of
<br />benthic productivity in these four habitats, which include a stream, a shallow lake, a deep lake, and a seasonal lake.
<br />The ecology of these habitats, including physico-chemical aspects, is described.
<br />RESUMEN
<br />En los lagos y rfos de la cuenca de Cuatro Cienegas, se distinguen cuatro tipos de estromatolitos dulceacuicolas
<br />y estructuras carbonatadas asociadas: 1) Estromatolitos laminados y oncoidos producidos por Homoeothrix balearica
<br />y Schyzothrix lacustris con un patron superficial de pequenos bordes lobulados horizontales o microterrazas; 2)
<br />Duros, estromatolitos intrincados y oncoidos construidos por Gongrosira calcifera, cyanobacterias y diatomeas; 3)
<br />Grandes estromatolitos globosos no laminados con un patron superficial sinuosarnente corntgado, resultando del
<br />crecimiento de Dihhothrix bonetiana, Schyzothrix lacustris, Cyanostylon sp., y diatomeas; 4) Laminados
<br />estromatolitos cupulados construidos por el crecimiento secuential de Scytonema mirabile, Schyzothrix cffinis, y
<br />diatomeas. Estos estromatolitos y deptisitos microbianos relacionados, tales Como capas microbianas y travertines
<br />asociados con ellos, son los principales sustratos y fuentes de productividad bentica en cuatro habitats, que inchryen
<br />un arroyo, tin lago somero, un lago profundo y un lago estacional. En el trabajo se describe la ecologfa de estos
<br />habitats, incluyendo los aspectos fisicoquimicos.
<br />UNNIGAN, B.; MCELROY, D.M.; DOUGLAS, M.E. Dept. Zoology ad Museum, Arizona State University, Tempe, AZ
<br />Sexual dimorphism and morphological variation in Cichlasonta ntinckleyi
<br />from the Cuatro Ci6negas basin, Mexico
<br />Dimorfismo sexual y variacion morfolGgica en Cichlasonta ntinckleyi
<br />de la cuenca Cuatro Cienegas, Mexico
<br />KEYWORDS: trophic morph; detritivore; molluscivore; piscivore; Cichlasoma ntinckleyi; Cichlasorna beani; Cichlasonta cyanogttuatunt;
<br />multivariate morphometrics
<br />CLAVES: detritfvoro; malacofago; piscfvoro; Cichlasoma minckleyi; Cichlasonta beani; Cichlasoma cyanoguitatunt-, morfomeufa muhivariada
<br />ABSTRACT
<br />Cichlasoma (Parapetenia) minckleyi, an endemic species from Cuatro Cienegas, Coahuila, Mexico, has at least
<br />three distinct morphotypes: a detritivore, a molluscivore, and a piscivore. Phenotypic differences between these
<br />forms are so great that they have been treated as distinct species. An alternative hypothesis is that the morphs
<br />comprise one polymorphic species. In this project, we compared morphological variation by sex and age (= size)
<br />within and between papilliform and molariform morphs. This variation was then contrasted against that found in
<br />two other neotropical cichlid species: Cichlasoma (Parapetenia) beani and Cichlasorna (Herichthys) cyanoguttatum.
<br />Ten adult specimens of each sex were evaluated for 35 measurements collected with calipers. Data were tested for
<br />normality and within-group homogeneity, then subjected to PCA, CVA, UPGMA cluster analysis, and strict
<br />consensus of all trees. Probability values were adjusted for multiple comparisons via the Bonferroni technique. For
<br />C. beani and C. cyanoguttatum, males and females of each species clustered together, indicating that
<br />species-differences accounted for a significantly greater portion of morphological variation than did sexual
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