ABSTRACT
Systematic of the fish Petenia splendida (Perciformes: Cichlidae) of Lake Petén Itzá, Guatemala. The Lake Petén Itzá is located in the multiple use zone of the Maya Biosphere Reserve. It belongs to the subtropical moist forest (warm) life zone, and has very important flora and fauna diversities. Among the fish species, the white fish (Petenia splendida) is of high commercial value. The main goal of the present work was to clarify the taxonomic position of the two forms of the white fish in Petén (Guatemala), and to compare it with the Usumacinta (Mexico) form, based on the collected material from 1978 and 2006 (Usumacinta), and collections made during 2008 and 2009 in the Lake Petén Itzá. Samples were obtained from 10 different locations in the lake. From the total of 57 fish specimens collected, 50 fish were selected (25 yellow form and 25 silver form); besides, 21 specimens from 10 locations of the Usumacinta river in Mexico, from the Fish Collection, FCB, UANL. A total of 36 morphometric and 16 meristic characteristics, were analyzed, and also coloration, habitat and fishing method. This study reports the P. splendida of the Lake Petén Itzá with the following characteristics: the yellow form at a depth of 0.5-1.5m with dorsal fin XIV-(Xv)-XVI/11-(12)-13, the silver form at a depth of 2-3m with dorsal fin XIV-(XV)-XVI/10-(12)-13, and the Usumacinta form with a dorsal fin XIV-(XV)-XV/12-(13)-13. The discrimination analysis demonstrates a differentiation among the three analyzed populations. Some of the characteristics are the ocular diameter, the anal source-pelvic source distance and the dorsal source-anal source distance. The geographic area studied has a high diversity of fish fauna along the watershed, and it is possible to observe the anthropogenic damage, due to the overexploitation based the unapplicability of the existent regulation and the urbanization. If this situation continues it could jeopardize the survival of this emblematic specie. Rev. Biol. Trop. 59 (3): 1205-1216. Epub 2011 September 01.
El Lago Petén Itzá se ubica en la zona de usos múltiples de la Reserva de la Biosfera Maya, entre sus especies ícticas encontramos al pez blanco (Petenia splendida) de alto valor comercial. El propósito del presente trabajo es aclarar la posición taxonómica de las dos formas de pez blanco de Petén y compararlas con la forma del Usumacinta. Entre 2008 y 2009 se recolectaron 25 ejemplares de la forma amarilla y 25 de la plateada en 10 localidades del lago Petén Itzá y 21 en la cuenca del Usumacinta durante 1978 y 2006; se revisaron 36 características morfométricas y 16 merísticas, así como coloración, hábitat y forma de pesca. La P. splendida del Lago presenta las siguientes características: la forma amarilla se encuentra a una profundidad entre 0.5 y 1.5m, tiene aleta dorsal XIV-(XV)-XVI/11-(12)-13; la plateada esta a profundidades entre 2-3m, presenta aleta dorsal XIV-(XV)-XVI/10-(12)-13, mientras que la forma del Usumacinta posee aleta dorsal XIV-(XV)-XV/12-(13)-13. El análisis discriminante muestra una diferenciación entre las tres poblaciones analizadas aunque no es determinante. La fauna de peces de la cuenca del área de estudio presenta alta diversidad, se observa daño antropogénico producto de la sobreexplotación, por la falta de aplicación de la reglamentación existente y la urbanización.
Subject(s)
Animals , Cichlids/classification , Biodiversity , Guatemala , LakesABSTRACT
The mitotic and meiotic chromosomes of the tropical fish Petenia splendida (Cichlidae). The karyotype of bay snook, Petenia splendida, is described based on mitotic and meiotic stages of sixty larvae and twelve juveniles from Tabasco, Mexico. Standard cytological procedures with minor modifications were followed to obtain mitotic and meiotic chromosome spreads. One hundred chromosome slides were analyzed and 290 chromosome spreads were counted. High-quality spreads in mitosis and meiosis were used for karyotype analysis. Mitotic chromosome spreads showed 76.7 % of such cells with 2n=48 chromosomes, while meiotic spreads revealed 55.2 % with 24 chromosomes in haploid stage. Photographic documentation of eight highquality pictures showed that the karyotype consists of three pairs of bi-armed metacentric-submetacentric chromosomes (msm) and 21 pairs with uni-armed subtelocentric-acrocentric chromosomes (sta), with a fundamental number (FN) of 54 arms. Karyotype chromosomes were verified by analysis of haploid and diploid metaphases at meiotic stage I. Abundant chromosome spreads were observed more frequently on slides from larvae. No evidence of heteromorphism to discriminate sexual chromosomes was detected. There were "dot-like" chromatic bodies in both sexes and they were classified as "B" chromosomes. The karyotype of P. splendida is type "A", i.e. primitive in the Cichlid family, similar to other species of Cichlasoma. The occurrence of supernumerary chromosomes is still unknown: studies on the effects of pollution and hybridization might be important to understand that phenomenon. Rev. Biol. Trop. 56 (2): 895-907. Epub 2008 June 30.
Para describir los cromosomas del cariotipo en mitosis y meiosis de la mojarra tenguayaca P. splendida, se procesaron 60 larvas y doce jóvenes (seis hembras y seis machos) procedentes de Tabasco, México. Se emplearon los procedimientos citológicos clásicos para peces pequeños y grandes, con algunas modificaciones que permitieron obtener campos cromosómicos en meiosis y mitosis. Analizamos al microscopio 100 laminillas, contando 290 dispersiones cromosómicas. En mitosis, 76.7 % de los conteos dieron número modal diploide de 2N=48 cromosomas, mientras en meiosis el 55.2 % mostró 24 cromosomas en condición haploide. Se analizaron ocho de las mejores fotografías para establecer el cariotipo y se identificaron tres pares de cromosomas birrámeos metacéntricos-submetacéntricos (msm) y 21 pares de cromosomas monorrámeos subtelocéntricos-acrocéntricos (sta) con número fundamental (N.F) de 54 brazos. Se corroboró el cariotipo mediante el análisis de campos cromosómicos en estadio haploide y diploide de la meiosis I. Las dispersiones cromosómicas tuvieron un número mayor en larvas que en jóvenes. No hubo diferencias heteromórficas para distinguir cromosomas sexuales. Sin embargo, se observó la presencia de cuerpos cromáticos en forma de puntos, como una característica propia de los microcromosomas "B". Para esta familia, el cariotipo de P. splendida es primitivo o tipo "A"; y es estrechamente parecido al del género Cichlasoma. El origen de los cromosomas supernumerarios es un fenómeno aun desconocido en los cíclidos por lo que faltan estudios relacionados con el daño causado por la contaminación y la hibridación.