Comparison of traditional and DNA metabarcoding samples for monitoring tropical soil arthropods (Formicidae, Collembola and Isoptera).

The soil fauna of the tropics remains one of the least known components of the biosphere. Long-term monitoring of this fauna is hampered by the lack of taxonomic expertise and funding. These obstacles may potentially be lifted with DNA metabarcoding. To validate this approach, we studied the ants, springtails and termites of 100 paired soil samples from Barro Colorado Island, Panama. The fauna was extracted with Berlese-Tullgren funnels and then either sorted with traditional taxonomy and known, individual DNA barcodes ("traditional samples") or processed with metabarcoding ("metabarcoding samples"). We detected 49 ant, 37 springtail and 34 termite species with 3.46 million reads of the COI gene, at a mean sequence length of 233 bp. Traditional identification yielded 80, 111 and 15 species of ants, springtails and termites, respectively; 98%, 37% and 100% of these species had a Barcode Index Number (BIN) allowing for direct comparison with metabarcoding. Ants were best surveyed through traditional methods, termites were better detected by metabarcoding, and springtails were equally well detected by both techniques. Species richness was underestimated, and faunal composition was different in metabarcoding samples, mostly because 37% of ant species were not detected. The prevalence of species in metabarcoding samples increased with their abundance in traditional samples, and seasonal shifts in species prevalence and faunal composition were similar between traditional and metabarcoding samples. Probable false positive and negative species records were reasonably low (13-18% of common species). We conclude that metabarcoding of samples extracted with Berlese-Tullgren funnels appear suitable for the long-term monitoring of termites and springtails in tropical rainforests. For ants, metabarcoding schemes should be complemented by additional samples of alates from Malaise or light traps.

The family Opilioacaridae (Parasitiformes: Opilioacarida) in Mexico, description of two new species, new records, and geographical distribution.

Two new species of Neocarus (Opilioacarida: Opilioacaridae), N. haicolous n. sp. and N. queretanus n. sp., are described from mesophyll and pine-oak forests in the state of Querétaro, central Mexico. One species was described from adults and tritonymphs. Distribution and habitat preferences of all known collections of Opilioacarida are reviewed. In Mexico, they have been collected in all habitats, from semideserts areas to tropical forest and from to sea level in dunes to high temperate and cloud forest.

Mexico ants: incidence and abundance along the Nearctic-Neotropical interface.

Mexico is one of the most biodiverse countries in the world, with an important proportion of endemism mainly because of the convergence of the Nearctic and Neotropical biogeographic regions, which generate great diversity and species turnover at different spatial scales. However, most of our knowledge of the Mexican ant biota is limited to a few well-studied taxa, and we lack a comprehensive synthesis of ant biodiversity information. For instance, most of the knowledge available in the literature on Mexican ant fauna refers only to species lists by states, or is focused on only a few regions of the country, which prevents the study of several basic and applied aspects of ants, from diversity and distribution to conservation. Our aims in this data paper are therefore (1) to compile all the information available regarding ants across the Mexican territory, and (2) to identify major patterns in the gathered data set and geographic gaps in order to direct future sampling efforts. All records were obtained from raw data, including both unpublished and published information. After exhaustive filtering and updating information and synonyms, we compiled a total of 21,731 records for 887 ant species distributed throughout Mexico from 1894 to 2018. These records were concentrated mainly in the states of Chiapas (n = 6,902, 32.76%) and Veracruz de Ignacio de la Llave (n = 4,329, 19.92%), which together comprise half the records. The subfamily with the highest number of records was Myrmicinae (n = 10,458 records, 48.12%), followed by Formicinae (n = 3,284, 15.11%) and Ponerinae (n = 1,914, 8.8%). Most ant records were collected in the Neotropical region of the country (n = 12,646, 58.19%), followed by the Mexican transition zone (n = 5,237, 24.09%) and the Nearctic region (n = 3,848, 17.72%). Native species comprised 95.46% of the records (n = 20,745). To the best of our knowledge, this is the most complete data set available to date in the literature for the country. We hope that this compilation will encourage researchers to explore different aspects of the population and community research of ants at different spatial scales, and to aid in the establishment of conservation policies and actions. There are no copyright restrictions. Please cite this data paper when using its data for publications or teaching events.

New Species of the Genus Periglischrus (Acari: Spinturnicidae) from Monophyllus Bats (Chiroptera: Phyllostomidae) in the West Indies, Including a Morphometric Analysis of Its Intraspecific Variation.

The discovery of a new species, Periglischrus empheresotrichus, was determined through a review of museum collections, as well as a field survey of ectoparasites of island bats. This new species parasitizes on two bat species of the genus Monophyllus Leach, the Greater Antillean Long-tongued bat Monophyllus redmani Leach and the Lesser Antillean Long-tongued bat Monophyllus plethodon Miller. The female, male, deuthonymphs, and protonymph are described and illustrated. P. empheresotrichus n. sp. has an insular distribution, we evaluated the morphological variation of the adult populations, and concluded that intra-specific variation is correlated both with host species and locality (island) in the West Indies.

The Guild Concept: From Feudalism to Community Ecology / El concepto de gremio: del feudalismo a la ecología de comunidades

RESUMEN Se analiza el origen y evolución del término gremio, así como su aplicación en ecología, considerando las múltiples connotaciones que se le ha dado y la confusión que se ha generado por utilizarlo de forma indebida. De igual forma, se discute la importancia de homogenizar los términos y definir de manera clara a los gremios, a fin de tener un leguaje que permita entender los alcances del término sin ambigüedades. El uso del término, así como su persistencia en estudios ecológicos, sugiere que el mismo tiene relevancia considerable dependiendo de la forma y el modo en que es empleado. El uso inadecuado o derivado de este término es arriesgado y peligroso, dado que tiende a reducir el término a una palabra vacía con múltiples significados. Más que nada, esta trivialización constituye una amenaza al uso y significado adecuado del concepto de gremio en ecología.

ABSTRACT The origin and evolution of the term guild are analyzed, as well as its application in ecology, considering the multiple connotations that have been given and the confusion that has been generated by using it improperly. Likewise, the importance of homogenizing the terms and clearly defining the guilds is discussed, to have a language that allows understanding the scope of the term without ambiguities. The use of the term, as well as its persistence in ecological studies, suggests that it has considerable relevance depending on the form and the way it is used. The inappropriate or derivative use of this term is risky and dangerous since it tends to reduce the term to an empty word with multiple meanings. Also, this trivialization constitutes a threat to the proper use of the guild concept in ecology and its meaning as a whole.

First Mexican species of the genus Cosberella (Collembola, Hypogastruridae).

A new species of Cosberella is described and illustrated from a temperate forest of Citlaltépetl formation, Veracruz State. It is characterized by the following combination of characters: Th I with 2 + 2 dorsal setae; 2 + 2 axial setae on Th II-III; two capitate tenent hairs on each leg; unguiculus half the length of unguis; unguis with tooth; six dental setae and Abd VI without anal spines. A key for the species of the genus is included.

The surrounding landscape influences the diversity of leaf-litter ants in riparian cloud forest remnants.

Riparian vegetation is a distinctive and ecologically important element of landscapes worldwide. However, the relative influence of the surrounding landscape on the conservation of the biodiversity of riparian remnants in human-modified tropical landscapes is poorly understood. We studied the surrounding landscape to evaluate its influence on leaf-litter-ant alpha and beta diversity in riparian remnants in the tropical montane cloud forest region of central Veracruz, Mexico. Sampling was carried out in 12 sites with riparian vegetation during both rainy (2011) and dry (2012) seasons. Ten leaf-litter samples were collected along a 100-m transect per site and processed with Berlese-Tullgren funnels and Winkler sacks. Using remotely-sensed and ground-collected data, we characterized the landscape around each site according to nine land cover types and computed metrics of landscape composition and configuration. We collected a total of 8,684 ant individuals belonging to 53 species, 22 genera, 11 tribes, and 7 subfamilies. Species richness and the diversity of Shannon and Simpson increased significantly in remnants immersed in landscapes with a high percentage of riparian land cover and a low percentage of land covers with areas reforested with Pinus, cattle pastures, and human settlements and infrastructure. The composition of ant assemblages was a function of the percentage of riparian land cover in the landscape. This study found evidence that leaf-litter ants, a highly specialized guild of arthropods, are mainly impacted by landscape composition and the configuration of the focal remnant. Maintaining or improving the surrounding landscape quality of riparian vegetation remnants can stimulate the movement of biodiversity among forest and riparian remnants and foster the provision of ecosystem services by these ecosystems. Effective outcomes may be achieved by considering scientific knowledge during the early stages of riparian policy formulation, in addition to integrating riparian management strategies with broader environmental planning instruments.

Floral Visitors of Three Asteraceae Species in a Xeric Environment in Central Mexico.

We describe the spatial variation in the structure and composition of the communities of insects visiting the inflorescences of Flaveria ramosissima Klatt, Florestina pedata (Cav.) Cass., and Parthenium bipinnatifidum (Ort.) Rollins (Asteraceae) in a xeric environment in Central Mexico. Inflorescences of the three Asteraceae were visited by a total of 96 species of Hymenoptera, Diptera, Lepidoptera, Coleoptera, and Hemiptera. Total species richness of floral visitors to the three Asteraceae and total abundance of insects of Fl. pedata and P. bipinnatifidum did not differ between low and high vegetation cover sites. Total abundance of insects visiting the inflorescences of F. ramosissima and abundance of Hymenoptera in all three Asteraceae were higher at the low vegetation coverage (LVC) site than at the high vegetation coverage (HVC) one. Diversity of insects of Fl. pedata and P. bipinnatifidum was higher at the HVC site. However, in F. ramosissima diversity was higher at the LVC site. The communities of insects of each Asteraceae were dissimilar between sites. These differences can be attributed to variation in the abundance of Lepidophora (Diptera: Bombyliidae), Miridae (Hemiptera), Melyridae (Coleoptera), Tiphiidae (Hymenoptera), Myrmecocystus mexicanus Wesmael, and Dorymyrmex grandulus (Forel) (Hymenoptera: Formicidae). The first three insect groups were sensitive to LVC, high temperature, and low humidity, whereas the last three tolerated those same environmental conditions. Changes in temperature, humidity, and resources associated with vegetation coverage seem to differentially affect each species of floral visitors of the three Asteraceae species studied.

The diversity of ant communities (Hymenoptera: Formicidae) and their connections with other arthropods from three temperate forests of Central Mexico / Diversidad de comunidades de hormigas (Hymenoptera: Formicidae) y sus conexiones con otros artrópodos en tres bosques templados del centro de México

AbstractAnts have been considered useful for bioindication because of their ecological characteristics. Nonetheless, among the characteristics of a bioindicator group, there must be a consistent and replicable response to disturbance. In this sense, divergent reactions have been found, even between taxons narrowly related. The objective of this work was to compare the diversity of the ant communities in three different temperate forests with different levels of disturbance, and to correlate their abundance and diversity of species, with that found in other arthropod communities of the same forests. The work was carried out in three municipalities in the North of the State of Mexico, where three types of different forests were identified by their degree of disturbance. These types include: 1) primary forest (PF), with typical species of a conserved forest; 2) mixed forest (MF), with species of a conserved forest and a reforestation effort; and 3) reforested forest (RF), with species used in reforestation efforts and indicative of disturbance. In each sample, an area of 2 500 m2 was selected. Each area had 16 pitfalls apiece and they were placed 10 m away from each other. Samples were collected twice; one from February through March 2009 (dry season) and another from August through September 2010 (rainy season), which produced a total of 192 traps. Obtained specimens were identified at the most taxonomically specific level. All data captured was transformed to √n + 0.5 and diversity index levels of Shannon and Simpson were calculated, as well as richness of species for ants, beetles, grasshoppers, true bugs, and spiders. The values of richness, diversity, and abundance were correlated with the Pearson coefficient, and to evaluate possible causal relationships between these, a path analysis was performed. Results suggested an important influence of the site over ant communities, and values of richness, abundance and diversity were correlated with the communities of spiders, beetles, grasshoppers and true bugs, but not for all the sites studied. Responses to environmental changes are not only on the numeric proportions of abundance, richness and diversity, but also in the indirect and casual ecological interactions. Finally, the data seems to indicate that the responses of the ants to the environmental changes are not necessarily reflected on other organisms’ communities, so the ants’ role as bioindicators can be limited. Rev. Biol. Trop. 64 (2): 571-585. Epub 2016 June 01.

ResumenPor sus características ecológicas las hormigas se han considerado útiles para la bioindicación. Sin embargo, entre los rasgos de un grupo bioindicador, debe haber una respuesta consistente y repetible a la perturbación. En este sentido, se han encontrado respuestas divergentes, incluso entre taxones estrechamente relacionados. El objetivo de este trabajo fue comparar la diversidad de las comunidades de hormigas en tres tipos de bosque templado con diferente nivel de perturbación y correlacionar su abundancia, riqueza de especies y la diversidad con aquella que se encuentra en otras comunidades de artrópodos en los mismos bosques. El trabajo se realizó en tres localidades del norte del Estado de México donde fueron identificados tres tipos de bosque diferenciados por grado de disturbio: 1) bosque primario (PF), con especies típicas de un bosque conservado; 2) bosque mixto (MF) con especies de bosque conservado y propias de reforestación y 3) bosque reforestado (RF) con especies utilizadas en reforestación e indicadoras de pertubación. En cada tipo de bosque se seleccionó un área de 2 500 m2 donde fueron colocadas 16 trampas de caída con una separación de 10 m. Fueron realizadas dos recolectas una de febrero a marzo 2009 (estación seca) y otra de agosto a septiembre 2010 (estación lluviosa), lo que dio un total de 192 trampas. Los especímenes obtenidos fueron identificados al nivel taxonómico más específico posible. Todos los datos de las capturas fueron transformados a √n+0.5 y fueron calculados los índices de diversidad de Shannon y Simpson y riqueza de especies tanto para hormigas como para escarabajos, chapulines, chiches y arañas. Los valores de riqueza, diversidad y abundancia fueron correlacionados con el coeficiente de Pearson y para evaluar posibles relaciones causales entre estos se realizó un análisis de sendero. Los resultados sugieren una influencia importante del sitio sobre las comunidades de hormigas y sus valores de riqueza, abundancia y diversidad están correlacionadas con las comunidades de arañas, escarabajos, chapulines y chinches, pero no para todos los sitios estudiados. Las respuestas a los cambios ambientales no sólo están en las proporciones numéricas de la abundancia, riqueza y diversidad sino también en las interacciones ecológicas indirectas y causales. Los resultados sugieren que las respuestas de las hormigas a los cambios ambientales no necesariamente se reflejan sobre comunidades de otros organismos por lo que su papel como bioindicadores puede ser limitado.

The diversity of ant communities (Hymenoptera: Formicidae) and their connections with other arthropods from three temperate forests of Central Mexico.

Ants have been considered useful for bioindication because of their ecological characteristics. Nonetheless, among the characteristics of a bioindicator group, there must be a consistent and replicable response to disturbance. In this sense, divergent reactions have been found, even between taxons narrowly related. The objective of this work was to compare the diversity of the ant communities in three different temperate forests with different levels of disturbance, and to correlate their abundance and diversity of species, with that found in other arthropod communities of the same forests. The work was carried out in three municipalities in the North of the State of Mexico, where three types of different forests were identified by their degree of disturbance. These types include: 1) primary forest (PF), with typical species of a conserved forest; 2) mixed forest (MF), with species of a conserved forest and a reforestation effort; and 3) reforested forest (RF), with species used in reforestation efforts and indicative of disturbance. In each sample, an area of 2 500 m2 was selected. Each area had 16 pitfalls apiece and they were placed 10 m away from each other. Samples were collected twice; one from February through March 2009 (dry season) and another from August through September 2010 (rainy season), which produced a total of 192 traps. Obtained specimens were identified at the most taxonomically specific level. All data captured was transformed to √n + 0.5 and diversity index levels of Shannon and Simpson were calculated, as well as richness of species for ants, beetles, grasshoppers, true bugs, and spiders. The values of richness, diversity, and abundance were correlated with the Pearson coefficient, and to evaluate possible causal relationships between these, a path analysis was performed. Results suggested an important influence of the site over ant communities, and values of richness, abundance and diversity were correlated with the communities of spiders, beetles, grasshoppers and true bugs, but not for all the sites studied. Responses to environmental changes are not only on the numeric proportions of abundance, richness and diversity, but also in the indirect and casual ecological interactions. Finally, the data seems to indicate that the responses of the ants to the environmental changes are not necessarily reflected on other organisms' communities, so the ants' role as bioindicators can be limited.

Arthropod Distribution in a Tropical Rainforest: Tackling a Four Dimensional Puzzle.

Quantifying the spatio-temporal distribution of arthropods in tropical rainforests represents a first step towards scrutinizing the global distribution of biodiversity on Earth. To date most studies have focused on narrow taxonomic groups or lack a design that allows partitioning of the components of diversity. Here, we consider an exceptionally large dataset (113,952 individuals representing 5,858 species), obtained from the San Lorenzo forest in Panama, where the phylogenetic breadth of arthropod taxa was surveyed using 14 protocols targeting the soil, litter, understory, lower and upper canopy habitats, replicated across seasons in 2003 and 2004. This dataset is used to explore the relative influence of horizontal, vertical and seasonal drivers of arthropod distribution in this forest. We considered arthropod abundance, observed and estimated species richness, additive decomposition of species richness, multiplicative partitioning of species diversity, variation in species composition, species turnover and guild structure as components of diversity. At the scale of our study (2 km of distance, 40 m in height and 400 days), the effects related to the vertical and seasonal dimensions were most important. Most adult arthropods were collected from the soil/litter or the upper canopy and species richness was highest in the canopy. We compared the distribution of arthropods and trees within our study system. Effects related to the seasonal dimension were stronger for arthropods than for trees. We conclude that: (1) models of beta diversity developed for tropical trees are unlikely to be applicable to tropical arthropods; (2) it is imperative that estimates of global biodiversity derived from mass collecting of arthropods in tropical rainforests embrace the strong vertical and seasonal partitioning observed here; and (3) given the high species turnover observed between seasons, global climate change may have severe consequences for rainforest arthropods.

Value of Riparian Vegetation Remnants for Leaf-Litter Ants (Hymenoptera: Formicidae) in a Human-Dominated Landscape in Central Veracruz, Mexico.

Riparian remnants are linear strips of vegetation immediately adjacent to rivers that may act as refuges for biodiversity, depending on their habitat quality. In this study, we evaluated the role of riparian remnants in contributing to the diversity of leaf-litter ants by determining the relationship between ant diversity and several riparian habitat characteristics within a human-dominated landscape in Veracruz, Mexico. Sampling was carried out in 2012 during both dry and rainy seasons at 12 transects 100 m in length, where 10 leaf-litter samples were collected along each transect and processed with Berlese-Tullgren funnels and Winkler sacks. A total of 8,684 individuals belonging to 53 species, 22 genera, and seven subfamilies were collected. The observed mean alpha diversity accounted for 34.4% of the total species recorded and beta diversity for 65.6%. Species richness and composition were significantly related to litter-layer depth and soil compaction, which could limit the distribution of ant species depending on their nesting, feeding, and foraging habits. Riparian remnants can contribute toward the conservation of ant assemblages and likely other invertebrate communities that are threatened by anthropogenic pressures. In human-dominated landscapes where remnants of riparian vegetation give refuge to a diverse array of myrmecofauna, the protection of the few remaining and well-preserved riparian sites is essential for the long-term maintenance of biodiversity.

Soil microarthropods and their relationship to higher trophic levels in the Pedregal de San Angel Ecological Reserve, Mexico.

Soil fauna is essential for ecosystem dynamics as it is involved in biogeochemical processes, promotes nutrient availability, and affects the animal communities associated with plants. In this study, we examine the possible relationship between the soil microarthropod community on foliage production and quality of the shrub Pittocaulon praecox. We also examine the arthropods associated to its foliage, particularly the size of the main herbivores and of their natural enemies, at two sites with contrasting vegetation cover and productivity. The diversity of soil microarthropods was assessed from soil samples collected monthly under P. praecox individuals over 13 mo. Specimens collected were identified to species or morphospecies. Shrub foliage productivity was evaluated through the amount of litter produced. Resource quality was assessed by the mean content (percentage by weight) of N, C, S, and P of 30 leaves from each shrub. The mean size of herbivores and their natural enemies were determined by measuring 20 adult specimens of each of the most abundant species. We found a higher species richness of soil microarthropods and foliar arthropods in the open site, although the diversity of foliage arthropods was lower in the closed site. Shrubs growing in the closed site tend to produce more, larger, and nutritionally poorer (lower nitrogen content) leaves than open site. Herbivores and their natural enemies were also larger in the closed site. We found a significant positive relationship between the diversity and species richness of foliar arthropods and the nitrogen content of leaves. In general, species richness and diversity of both the foliar and soil fauna, as well as the size of organisms belonging to higher trophic levels, were affected by vegetation cover and primary productivity at each site. These findings highlight the need to simultaneously consider at least four trophic levels (soil organisms, plants, herbivores, and natural enemies) to better understand the functioning of these systems and their responses to environmental changes.

Arthropod diversity in a tropical forest.

Most eukaryotic organisms are arthropods. Yet, their diversity in rich terrestrial ecosystems is still unknown. Here we produce tangible estimates of the total species richness of arthropods in a tropical rainforest. Using a comprehensive range of structured protocols, we sampled the phylogenetic breadth of arthropod taxa from the soil to the forest canopy in the San Lorenzo forest, Panama. We collected 6144 arthropod species from 0.48 hectare and extrapolated total species richness to larger areas on the basis of competing models. The whole 6000-hectare forest reserve most likely sustains 25,000 arthropod species. Notably, just 1 hectare of rainforest yields >60% of the arthropod biodiversity held in the wider landscape. Models based on plant diversity fitted the accumulated species richness of both herbivore and nonherbivore taxa exceptionally well. This lends credence to global estimates of arthropod biodiversity developed from plant models.

[Distribution and diversity of springtails (Hexapoda: Collembola) on the altitudinal gradient of a temperate forest in Mexico]. / Distribución y diversidad de colémbolos (Hexapoda: Collembola) en el gradiente altitudinal de un bosque templado en México.

Mountain ecosystems have shown slow mineralization activity due to weather conditions, and to some groups with arthropods with special roles. The Collembola is an important group for litter fragmentation, showing different distribution patterns. The objective of the present study was to determine the diversity of Collembola along a volcano altitudinal gradient. For this, four sampling expeditions evaluated four altitudinal levels (I = 2 753, II = 3 015, III = 3 250 and IV = 3 687 masl) in Iztaccihuatl Volcano, from November 2003, and March, June and August 2004. Shannon diversity (H'), Pielou evenness (J') and Simpson dominance (1/lambda) indices were calculated. The similarity between the associations of springtails between the sampling sites was evaluated by a cluster analysis using the Pearson correlation coefficient, as distance and the unpaired arithmetic averages (UPGMA) as amalgamation method. A total of 24 075 springtails, distributed in 12 families, 46 genera and 86 species was collected. The higher species abundance was found at the altitudinal area II. The lowest diversity value was recorded in IV, while the higher diversity values were found in III. Significant differences between Shannon indices were found between zones II-III (t(0.01, 187) = 4.11, p < 0.05) and between III-IV (t(0.01, 187) = 3.8, p < 0.05) according to modified t-test. When considering sampling dates, no significant differences were found. The dendrogram showed that in composition the level I is more homogeneous throughout the year. In conclusion, a statistically significant seasonal variation in springtail abundances was not found, but it was observed that, the lower altitude (I) resulted more homogeneous along the studied period, followed by level II and III. There is a particular assemblage of springtails community in each altitudinal area studied; in general, the sites with low slope resulted more diverse in Collembola communities. These results show that there are important factors such as altitude, vegetation type and microhabitat heterogeneity that may affect the distribution of springtails communities along an altitudinal gradient.

Distribución y diversidad de colémbolos (Hexapoda: Collembola) en el gradiente altitudinal de un bosque templado en México

Distribution and diversity of springtails (Hexapoda: Collembola) on the altitudinal gradient of a temperate forest in Mexico. Mountain ecosystems have shown slow mineralization activity due to weather conditions, and to some groups with arthropods with special roles. The Collembola is an important group for litter fragmentation, showing different distribution patterns. The objective of the present study was to determine the diversity of Collembola along a volcano altitudinal gradient. For this, four sampling expeditions evaluated four altitudinal levels (I=2 753, II=3 015, III=3 250 and IV=3 687 masl) in Iztaccihuatl Volcano, from November 2003, and March, June and August 2004. Shannon diversity (H’), Pielou evenness (J’) and Simpson dominance (1/λ) indices were calculated. The similarity between the associations of springtails between the sampling sites was evaluated by a cluster analysis using the Pearson correlation coefficient, as distance and the unpaired arithmetic averages (UPGMA) as amalgamation method. A total of 24 075 springtails, distributed in 12 families, 46 genera and 86 species was collected. The higher species abundance was found at the altitudinal area II. The lowest diversity value was recorded in IV, while the higher diversity values were found in III. Significant differences between Shannon indices were found between zones II-III (t0.01, 187=4.11, p<0.05) and between III-IV (t0.01, 187=3.8, p<0.05) according to modified t-test. When considering sampling dates, no significant differences were found. The dendrogram showed that in composition the level I is more homogeneous throughout the year. In conclusion, a statistically significant seasonal variation in springtail abundances was not found, but it was observed that, the lower altitude (I) resulted more homogeneous along the studied period, followed by level II and III. There is a particular assemblage of springtails community in each altitudinal area studied; in general, the sites with low slope resulted more diverse in Collembola communities. These results show that there are important factors such as altitude, vegetation type and microhabitat heterogeneity that may affect the distribution of springtails communities along an altitudinal gradient. Rev. Biol. Trop. 59 (1): 315-327. Epub 2011 March 01.

Los colémbolos son fragmentadores importantes de la hojarasca, presentan diferentes patrones de distribución a lo largo de un gradiente altitudinal. El objetivo del presente trabajo es determinar la diversidad y distribución de Collembola en el volcán Iztaccíhuatl. Para ello, se realizaron cuatro muestreos, a lo largo de un año en cuatro pisos altitudinales (I=2 753, II=3 015, III=3 250 y IV=3 687m.s.n.m.) y se calcularon los índices de diversidad de Shannon, equitatividad de Pielou y dominancia de Simpson, para compararlos mediante una prueba de t modificada. Los resultados muestran al piso III como el más diverso, y la mayor equitatividad se encuentra en el II. Además, se hallaron diferencias significativas entre los pisos II-III (t0.01, 187=4.11, p<0.05) y entre III-IV (t0.01, 187=3.8, p<0.05). Para las fechas de recolección no obtuvimos diferencias significativas (t0.01, 187=2.71, p<0.05). Al final encontramos que la temporalidad no incrementa la diversidad (estadísticamente), por consiguiente, condiciones como la altitud, vegetación y heterogeneidad geográfica crean microambientes, para protegerse de inclemencias ambientales. El piso I es el más homogéneo, seguida por el II y el III, además hallamos que los sitios más diversos son aquellos de pendientes menos pronunciadas.

Estructura de la comunidad de colémbolos (Hexapoda: Collembola) en musgos corticícolas en el gradiente altitudinal de un bosque subhúmedo de México

Structure of the Collembolan community (Hexapoda: Collembola) in bark mosses along an altitudinal gradient of a subhumid forest in Mexico. The structure of the community of moss springtails on oak and fir bark in the forests at the NW slope of iztaccíhuatl Volcano, State of Mexico, is analyzed. The study included four samplings (November 2003, March-June-August 2004), carried out in three altitudes I: 2 750 m, II: 2 930 and 3 250 m a.s.l. Calculated indexes were: species richness (S), Shannon’s diversity index (H’), Pielou’s evenness index (J’) and Simpson dominance (). An ANOVA of two way test was used to evaluate the effect of altitude and sampling date on the total density of the springtails. The total number of species was 24 (altitude I=17, altitude II=14, altitude III=13). The greatest density was at altitude III and the highest species richness at altitude I. Americabrya arida and Willowsia mexicana were dominant. There is a positive significant effect of altitude on their density. The highest Sörensen similarity between communities was 59 % ( altitudes II and III). Rev. Biol. Trop. 56 (2): 739-748. Epub 2008 June 30.

Se presentan datos sobre la estructura de la comunidad de colémbolos en musgos corticícolas, de un bosque de encino y abetos en la vertiente NW del Volcán Iztaccíhuatl, Estado de México, México. El estudio comprendió cuatro muestreos (noviembre de 2003, marzo, junio y agosto de 2004), realizados en tres altitudes I: 2 750 m; II: 2 930 m y III: 3 350 m snm. En cada altitud, se calculó la riqueza de especies (S), los índices de diversidad de Shannon (H’), Equitatividad de Pielou (J’) y, dominancia de Simpson (). Se utilizó un análisis de varianza de dos vías (ANOVA) para evaluar el efecto de la altitud y fecha de muestreo, sobre la densidad total de los colémbolos. El número total de especies fue de 24, variando de 13 para la altitud mayor a 17 en la menor. La mayor densidad se encontró a mayor altitud. Americabrya arida y Willowsia mexicana fueron las especies dominantes, y se encontró un efecto positivo significativo de la altitud sobre sus densidades. La mayor similitud entre comunidades de acuerdo con el índice de Sörensen se presentó entre las altitudes II y III, con un 59%.

[Structure of the Collembolan community (Hexapoda: Collembola) in bark mosses along an altitudinal gradient of a subhumid forest in Mexico]. / Estructura de la comunidad de colémbolos (Hexapoda: Collembola) en musgos corticicolas en el gradiente altitudinal de un bosque subhúmedo de México.

The structure of the community of moss springtails on oak and fir bark in the forests at the NW slope of Iztaccihuatl Volcano, State of Mexico, is analyzed. The study included four samplings (November 2003, March-June-August 2004), carried out in three altitudes I: 2750 m, II: 2 930 and 3 250 m a.s.l. Calculated indexes were: species richness (S), Shannon's diversity index (H'), Pielou's evenness index (J') and Simpson dominance (lamda). An ANOVA of two way test was used to evaluate the effect of altitude and sampling date on the total density of the springtails. The total number of species was 24 (altitude I=17, altitude II=14, altitude III=13). The greatest density was at altitude III and the highest species richness at altitude I. Americabrya arida and Willowsia mexicana were dominant. There is a positive significant effect of altitude on their density. The highest Sörensen similarity between communities was 59% (altitudes II and III).

Estructura de la comunidad de cunáxidos (Acarina) edáficos de una selva baja caducifolia en Chamela, México

Community structure of edaphic cunaxids (Acarina) from a lowland dry forest in Chamela, México. The structure community of cunaxids mites was studied at a tropical dry forest in the Chamela Biological Station, Jalisco, Mexico. Monthly samples of litter and soil were taken during one year (July 1991-May 1992), in two small watersheds. A total of 43 species was recorded. We studied their abundance, species frequency (F), rareness and relative abundance (Ar), density (ind m-2), species richness (S), Shannon’s diversity index (H’), and Pielou’s evenness index (J’). The species richness was similar in litter and soil (38 species), but species composition was different. The higher density was found in soil, with 5 074 ind m-2; litter density was 2 199 ind m-2. The subfamilies with the highest density in both biotopes were Coleoscirinae (H=1 127 ind m-2; S=2 235 ind m-2) and Cunaxiinae (H=887 ind m-2; S = 1 936 ind m-2). The genus Pulaeus had the most species, and all were new to science. Mean and variance indicate an aggregate distribution for these cunaxids. By permanency and relative abundance, the dominant species were: Cunaxa potchensis, Coleoscirus simplex, Armascirus harrisoni, Cunaxoides sp. nov. 1, Cunaxoides sp. nov. 2, Pulaeus sp. nov. 15 and Pulaeus sp. nov. 16. An significant effect of the month and the biotope were recorded on the diversity and composition of cunaxid communities. Most of the species presented a significant effect of the month (24 spp.) and biotope (23 spp.), and five species only had a significant effect of the watersheds. The highest similarity was in litter (75 %) and soil (74 %). The highest temporal variation in density, diversity and species richness was from April through June in litter, and from September through November in soil. The evenness was constant in both biotopes. in the dry period the soil presented higher values of density, while in the litter it was in the rainy season. The species with high soil density (February-June: dry season) in both watersheds, were: C. simple, C. potchensis, Cunaxa sp. nov. 1, Cunaxa sp. nov. 2, C. veracruzana, Dactyloscirus sp. nov. 2, A. harrisoni, Cunaxoides sp. nov. 1, Cunaxoides sp. nov. 2, P. pectinatus, Pulaeus sp. nov. 14, Pulaeus sp. nov. 15 and Pulaeus sp. nov. 16. They were the most representative species in the soil and litter of Chamela communities. The most abundant dry season species were C. potchensis in the soil and A. harrisoni in the litter. Rev. Biol. Trop. 55 (3-4): 911-930. Epub 2007 December, 28.

Se estudió la variación espacial y temporal de la estructura de la comunidad de los cunáxidos edáficos de una selva baja caducifolia en Chamela, Jalisco, México. Se tomaron muestras mensuales de suelo y hojarasca durante un año (Julio 1991-Junio 1992) en dos cuencas. Registramos 43 especies, para las cuales se proporciona su abundancia, frecuencia, abundancia relativa, riqueza, densidad, diversidad, equitatividad y rareza. El número de especies fue similar en el suelo y la hojarasca, pero ambos biotopos difirieron en su composición. La mayor densidad se encontró en el suelo con 5 074 ind m-2. Pulaeus fue el género que presentó la mayor riqueza. De acuerdo a la permanencia y abundancia relativa, las especies dominantes, tanto en el suelo y como en la hojarasca, fueron: Colescirus simples, Cunaxa potchensis, Armascirus harrisoni y Pulaeus sp. nov. 16. El suelo presentó una mayor dominancia y densidad, siendo C. potchensis, C. simplex, A. harrisoni Cunaxoides sp. nov. 1 y Pulaeus sp. nov. 16 las especies más abundantes. En la hojarasca se registró una mayor variación temporal en cuanto a densidad, diversidad y riqueza entre abril a junio, y en el suelo de septiembre a noviembre.

[Community structure of edaphic cunaxids (Acarina) from a lowland dry forest in Chamela, Mexico]. / Estructura de la comunidad de cunáxidos (Acarina) edáficos de una selva baja caducifolia en Chamela, México.

The structure community of cunaxids mites was studied at a tropical dry forest in the Chamela Biological Station, Jalisco, Mexico. Monthly samples of litter and soil were taken during one year (July 1991-May 1992), in two small watersheds. A total of 43 species was recorded. We studied their abundance, species frequency (F), rareness and relative abundance (Ar), density (ind m(-2)), species richness (S), Shannon's diversity index (H'), and Pielou's evenness index (J'). The species richness was similar in litter and soil (38 species), but species composition was different. The higher density was found in soil, with 5 074 ind m(-2); litter density was 2 199 ind m(-2). The subfamilies with the highest density in both biotopes were Coleoscirinae (H=1127 ind m(-2); S=2235 ind m(-2)) and Cunaxiinae (H=887 ind m(-2); S=1936 ind m(-2)). The genus Pulaeus had the most species, and all were new to science. Mean and variance indicate an aggregate distribution for these cunaxids. By permanency and relative abundance, the dominant species were: Cunaxa potchensis, Coleoscirus simplex, Armascirus harrisoni, Cunaxoides sp. nov. 1, Cunaxoides sp. nov. 2, Pulaeus sp. nov. 15 and Pulaeus sp. nov. 16. An significant effect of the month and the biotope were recorded on the diversity and composition of cunaxid communities. Most of the species presented a significant effect of the month (24 spp.) and biotope (23 spp.), and five species only had a significant effect of the watersheds. The highest similarity was in litter (75 %) and soil (74 %). The highest temporal variation in density, diversity and species richness was from April through June in litter, and from September through November insoil. The evenness was constant in both biotopes. In the dry period the soil presented higher values of density, while in the litter it was in the rainy season. The species with high soil density (February-June: dry season) in both watersheds, were: C. simple, C. potchensis, Cunaxa sp. nov. 1, Cunaxa sp. nov. 2, C. veracruzana, Dactyloscirus sp. nov. 2, A. harrisoni, Cunaxoides sp. nov. 1, Cunaxoides sp. nov. 2, P. pectinatus, Pulaeus sp. nov. 14, Pulaeus sp. nov. 15 and Pulaeus sp. nov. 16. They were the most representative species in the soil and litter of Chamela communities. The most abundant dry season species were C. potchensis in the soil and A. harrisoni in the litter.