Coleópteros necrófilos (Scarabaeidae, Silphidae y Trogidae) de Malinalco, Estado de México, México / Necrophilous coleoptera (Scarabaeidae, Silphidae y Trogidae) of Malinalco, State of Mexico, Mexico

Collections were made during one year, between August 2005 and July 2006, in Malinalco, State of Mexico, in three sites of tropical deciduous forest, a pasture and a induced forest of pine-oak, established in a altitudinal gradient ranging from 1,253 m to 2,300 m. The total of 7,680 specimens Scarabaeidae, Silphidae and Trogidae were captured through NTP-80, representing 18 genera and 38 species. Onthophagus and Canthon contained 46 percent of the richness of Scarabaeidae. The more distant sites were complementary in their species composition. The lowest complementarity occurred between sites with tropical deciduous forest. It revises the material collected through pitffal traps and light traps funnel type, increasing the list of 38 to 50 species in the study area. Between 40 percent and 50 percent of the species in Malinalco are distributed in localities of the province of the basin Balsas and localities of the province of the Sierra Madre del Sur, and 30 percent in the localities of the province of Pacifica coast. For the first time 17 species of Scarabaeidae and three Trogidae were reported for the State of Mexico.

Insectos acuáticos asociados a los lagos interdunarios de la región central del Estado de Veracruz, México / Aquatic insects in dune lakes of the central region of the Gulf of Mexico

El objetivo de este trabajo fue registrar la presencia de insectos acuáticos durante la estación de lluvias y durante las secas en 15 lagos interdunarios localizados en la zona costera del Golfo de México. Estos sistemas albergan una riqueza de 62 familias en general, registrándose en época de lluvias un total de 60 familias y en secas 46. En ambas épocas Coleoptera es el orden con mayor número de familias seguido de Diptera. A pesar que la primera es la más diversa no es la más abundante, ya que la familia Chironomidae (Diptera) engloba un 40 por ciento de la abundancia total de individuos capturados. La utilización de taxa de alto rango para cuantificar la biodiversidad se basa en el principio de que un número elevado de géneros y/o familias se supone que alberga un mayor número de especies. No se encontraron diferencias significativas en la riqueza de familias entre la época de secas y la de lluvias para cada lago. La estructura trófica encontrada está dominada por familias de detritófagos (57 por ciento), seguido de los depredadores (38 por ciento) y el resto son herbívoros. Ello es un indicador de que estos cuerpos de agua presentan gran cantidad de materia orgánica. Con los resultados que se obtuvieron nuestra hipótesis de trabajo se rechazó, ya que no se encontraron diferencias en la riqueza, diversidad y estructura trófica de los lagos entre las épocas de secas y las de lluvias.

The aim of this study is to register the presence of aquatic insects during the rainy and dry seasons, in 15 dune lakes of the Gulf of Mexico's coastal zone. These ecosystems lodge a wealth of 62 families, 60 of them present during the rainy season and 46 during the dry period. At both times Coleoptera is the order with a greater number of families, followed by Diptera. The first one is the most diverse, but Chironomidae (Diptera) is the most abundant, representing 40 percent of the total number of individuals. We used high rank taxa to quantify the biodiversity based on the principle that a high number of families or genus is supposed to include a greater number of species. There were not significant differences in the alpha diversity within the same lake during the two climatic seasons. The trophic structure is dominated by the detritivorous groups (57 percent of scrapers, collectors, gatherers, shredders), followed by predators (38 percent) and herbivores (5 percent). These numbers indicate that dune lakes have a great amount of organic matter. The results obtained contradict our working hypothesis, thus it was rejected, in summary, because there were no important differences in family composition, abundance of individuals and trophic structure of the lakes between the rainy and dry seasons.

Fauna de Coleópteros Scarabaeidae Laparosticti y Trogidae (Coleoptera: Scarabaeoidea) asociados al Bosque Mesofilo de Montaña, cafetales bajo sombra y comunidades derivadas en el Centro de Veracruz, México / Fauna of Scarabaeidae-Laparosticti and Trogidae (Coleoptera: Scarabaeoidea) associated with Cloud Forest, shaded coffee plantations and transformed communities in Central Veracruz, Mexico

Durante 16 meses de colectas entre abril 2002 y julio 2003, en el centro del estado de Veracruz, en tres fragmentos de bosque mesófilo de montaña, tres cafetales bajo sombra, un cafetal sin sombra, un acahual y un pastizal, establecidos en un gradiente altitudinal (1000-1400 m), cada 200 m, se obtuvieron 9982 especimenes de Scarabaeidae y Trogidae que representan a 21 géneros y 50 especies. Los géneros Ataenius Harold, Onthophagus Latreilley Aphodius Illiger reúnen al 48 por ciento de las especies de Scarabaeidae. En el gradiente altitudinal se obtuvo que a mayor altitud menor riqueza específica, a los 1000 m coexisten 36 especies, entre los 1200-1300 m 27 especies y a 1400 m 26 especies. La abundancia general en el gradiente altitudinal sigue un patrón de pocas especies abundantes y muchas especies con pocos especimenes. La actividad de los escarabajos está relacionada con la precipitación, observándose con precipitaciones mayores a 100 mm al inicio de la época de lluvias un incremento en la riqueza específica en las nueve comunidades. Durante la época de lluvias coexisten 44 especies, en época de nortes 22 especies y en época de secas 24 especies. Los gremios tróficos están representados por el 40 por ciento de los saprófagos que se alimentan de materia orgánica en descomposición de origen vegetal, y por el 60 por ciento los saprófagos que se alimentan de materia orgánica en descomposición de origen animal (necrófagos 30 por ciento, coprófagos 26 por ciento, telio-necrófagos 4 por ciento).

Beetles were collected from April 2002 to July 2003 from the following sites in the centre of the state of Veracruz located every 200 m along an altitudinal gradient (1000 - 1400 m asl): three fragments of cloud forest, three shaded coffee plantations, an open canopy coffee plantation, secondary forest, and a pasture. A total of 9,982 specimens were captured, belonging to the families Scarabaeidae and Trogidae, and representing 21 genera and 50 species. The genera Ataenius Harold, Onthophagus Latreille and Aphodius Illiger represented 48 percent of the species of Scarabaeidae. Species richness was found to decrease with increasing altitude; there were 36 species at 1000 m asl, 27 species between 1200 and 1300 m asl, and 26 species at 1400 m asl. Abundance along the altitudinal gradient follows a pattern of few abundant species and many species with few specimens. Beetle activity is related to precipitation. In the nine communities studied, species richness was observed to increase when precipitation was greater than 100 mm at the beginning of the rainy season. On the landscape scale, there were 44 species during the rainy season, 22 during the windy nortes season, and 24 during the dry season. In terms of trophic guild, 40 percent of the beetles captured were saprophagous that feed on decomposing organic material from plants and 60 percent were saprophagous that feed on decomposing organic material from animals (30 percent necrophagous, 26 percent coprophagous, 4 percent telio-necrophagous).

Una nueva especie Mexicana de Dichotomius Hope (Coleoptera: Scarabaeidae) y clave para la identificación de las especies del grupo carolinus / A new Mexican species of Dichotomius Hope (Coleoptera: Scarabaeidae) and a key to species of the carolinus group

Se describe una nueva especie de Dichotomius Hope, con material proveniente de los estados de Yucatán y Quintana Roo, México. Dichotomius maya sp. nov. es incluida en una nueva clave para la identificación de las especies del grupo carolinus el cual posee una distribución en América del norte y Centroamérica y comprende además las siguientes especies: D. carolinus L., D. colonicus (Say), D. annae Kohlmann & Solís y D. amicitiae Kohlmann & Solís.

A new species of Dichotomius Hope is described based on specimens from states of Yucatan and Quintana Roo, Mexico. Dichotomius maya n. sp. is included in a new key to species of the carolinus group, which comprises besides new species described herein, the following species with North American and Central American distribution: D. carolinus L., D. colonicus (Say), D. annae Kohlmann & Solís and D. amicitiae Kohlmann & Solís.