Leaf litter decomposition and macroinvertebrate assemblages in a tropical Andean stream (Ibagué, Colombia) / Descomposición de hojas y ensamblaje de macroinvertebrados en una quebrada tropical andina (ibagué, colombia)

RESUMEN El funcionamiento ecosistémico de quebradas o arroyos altoandinos de Colombia aún es poco conocido. El objetivo de este estudio fue evaluar la descomposición de hojas de aliso (Alnusacuminata), sietecueros (Andesanthuslepidotus) y una mezcla 1:1 de estas especies (Mixto), utilizando bolsas de hojarasca de poro amplio y fino, de 5 y 0,5 mm respectivamente, en la quebrada Las Perlas (2390 m.s.n.m.). Se recolectaron cuatro réplicas por tratamiento a los 3, 7, 15, 20 y 30 días, y se analizó la descomposición y la colonización por invertebrados (densidad, grupos funcionales de alimentación-GFA). Las tasas de descomposición (k) fueron significativamente distintas entre tratamientos y durante el experimento: A. acuminata (62 % de pérdida de masa seca) > Mixto (53 %) > A. lepidotus (31 %), principalmente en la primera semana y hacia el final del estudio. El mayor valor de k se registró en A. acuminata (- 0,019 días1) y el menor en A. lepidotus (- 0,004 días1). La densidad de macroinvertebrados colonizadores mostró una tendencia a aumentar durante el experimento, fue mayor en el día 20, y estuvo dominada principalmente por Diptera (Chironomidae, Simuliidae), Trichoptera (Hydroptilidae), Coleoptera (Elmidae) y Ephemeroptera (Leptohyphidae), mientras que en los GFA predominaron los recolectores, con los valores más altos en Mixto que en las especies por separado. En general, nuestros resultados sugieren que la colonización y la función de los invertebrados están relacionadas con la diversidad de hojas y sus mezclas, las cuales pueden definir la dinámica de la descomposición y de nutrientes en sistemas acuáticos tropicales altoandinos.

ABSTRACT The ecosystem functioning in headwater Colombian Andean streams is still poorly understood. The objective of this study was to evaluate the leaf decomposition of alder (Alnusacuminata), sietecueros (Andesanthus lepidotus) and a 1:1 mixture of the two species using coarse- (5 mm) and fine-mesh litter bags (0.5 mm) in the Las Perlas stream, a high-altitude tropical Andean aquatic system (2390 m.a.s.l.). A subset of 4-litterbags of each treatment was retrieved at 3, 7, 15, 20, and 30 days and analyzed for litter decomposition and invertebrate colonization (density, functional feeding groups-FFG). Decomposition rates (k) were significantly distinct between treatments and over the experiment: A. acuminata (62 % leaf dry mass loss) > Mixture (53 %) > A. lepidotus (31 %), mainly during the first week and toward the final phase of the study. The highest k-value was registered in A. acuminata (- 0.019 days1) and was lower in A. lepidotus (- 0.004 days1). Macroinvertebrate density tended to increase over the incubation period, was higher in the day 20, and was primarily dominated by Diptera (Chironomidae, Simuliidae), Trichoptera (Hydroptilidae), Coleoptera (Elmidae), and Ephemeroptera (Leptohyphidae), whereas the collectors predominated, attaining higher values in the Mixture than in the species alone. Overall, our results slightly suggest that invertebrate colonization and their function are related to the leaflitter diversity and mixing, which can define the dynamics of the decomposition and nutrients in tropical high-Andean aquatic systems.

Species richness under a vertebral stripe: integrative taxonomy uncovers three additional species of Pholidobolus lizards (Sauria, Squamata, Gymnophthalmidae) from the north-western Colombian Andes.

The systematic study of biodiversity underlies appropriate inference in most other fields of biological research, yet it remains hampered by disagreements on both theoretical and empirical issues such as the species concept and the operational diagnosis of a species. Both become particularly challenging in those lineages where morphological traits are evolutionarily constrained by their adaptive value. For instance, cryptic organisms often conserve or converge in their external appearance, which hinders the recognition of species boundaries. An integrative approach has been adopted to study microgeographic variation in the leaf-litter lizard Pholidobolusvertebralis and test three predictions derived from the evolutionary species concept. Molecular data provided unambiguous evidence of divergence among the three recovered new clades and a common evolutionary history for each of them. The broadly sympatric clades were indeed diagnosable from externally visible traits, such as head scales, adult size, and sexually dimorphic ventral colouration. Also, they barely overlapped on the phenotypic space that summarised 39 morphometric and meristic traits. These clades are described as three species and an available name is suggested for a recovered fourth clade. The geographic distribution of the new and proximate species suggests a role for elevation on evolutionary divergence; it also raises interesting questions on the speciation pattern of an otherwise underestimated cryptic lineage.

Chemistry Matters: High Leaf Litter Consumption Does Not Represent a Direct Increase in Shredders' Biomass.

Changes in riparian vegetation can alter the input and quality of leaf litter in aquatic ecosystems, but the effects of these changes on litter fragmentation by invertebrate shredder communities in tropical streams remain poorly studied. The caddisfly genus Phylloicus Müller, 1880 (Trichoptera: Calamoceratidae) is highly abundant in Neotropical streams, representing a great part of shredder biomass, which uses the allochthonous litter as a food resource and for case-building. We investigated leaf consumption by Phylloicus sp. under different leaf conditioning (leached and unleached) and plant species (Eucalyptus grandis, Erythrina falcata, and Inga uruguensis). The effects of leaf conditioning and plant species were measured using microcosm treatments, with one free Phylloicus sp. larva per 2-l microcosm, and a decomposition control to correct for microbial decomposition. Our study suggests that phosphorus and caloric values of leaf litter are more important than leaf hardness and nitrogen in driving leaf consumption by Phylloicus sp. On the one hand, higher consumption was observed in treatment with unleached leaves than in leached leaf treatment due to higher nutrient concentration and caloric values on unleached leaves. On the other hand, Phylloicus sp. larvae preferred leached leaves for case building over unleached leaves, as leached leaves are less prone to the activity of the decomposing community, thus lowering the need for constant case renewal. Finally, high litter consumption is not necessarily converted into biomass by Phylloicus sp. larvae. In this sense, Phylloicus sp. larvae showed selectivity for resources with high caloric content for consumption and low caloric content for case-building.

Tropical stream microcosms of isolated fungal species suggest nutrient enrichment does not accelerate decomposition but might inhibit fungal biomass production.

Terrestrial leaf litter is an essential energy source in forest streams and in many tropical streams, including Cerrado, litter undergoes biological decomposition mainly by fungi. However, there is a limited understanding of the contribution of isolated fungal species to in-stream litter decomposition in the tropics. Here we set a full factorial microcosms experiment using four fungal species (Aquanectria penicillioides, Lunulospora curvula, Pestalotiopsis submerses, and Pestalotiopsis sp.) incubated in isolation, two litter types (rapid and slow decomposing litter) and two nutrient levels (natural and enriched), all characteristics of Cerrado streams, to elucidate the role of isolated fungal species on litter decomposition. We found that all fungal species promoted litter mass loss but with contributions that varied from 1% to 8% of the initial mass. The fungal species decomposed 1.5 times more the slow decomposing litter and water nutrient enrichment had no effect on their contribution to mass loss. In contrast, fungal biomass was reduced by nutrient enrichment and was different among fungal species. We showed fungal contribution to decomposition depends on fungal identity and litter type, but not on water nutrients. These findings suggest that the identity of fungal species and litter types may have more important repercussions to in-stream decomposition than moderate nutrient enrichment in the tropics.

Soil phosphorus fractions and their relation to leaf litterfall in a central Amazonian terra firme rainforest / Frações de fósforo no solo e sua relação com a serrapilheira em uma floresta de terra firme na Amazônia central

Phosphorus (P) cycling is an important yet poorly studied aspect of the macronutrient balance in tropical rainforest ecosystems. As soil P occurs in different organic and inorganic forms (fractions) with varying degrees of lability, we hypothesized that these fractions will vary between soil types, and temporally within soil types. Additionally, we hypothesized a direct influence of leaf litterfall P input on soil total P and soil P fractions. We collected soil and leaf litter samples from three soil types in a central Amazonian lowland rainforest in Brazil over five months, and used a modified Hedleys fractionation method to determine six organic and inorganic soil P fractions, and also total, labile and residual P. Leaf litterfall P concentrations were determined colorimetrically. Soil inorganic and organic P fractions varied between soil types and across months, but soil type and month interactions were mostly non-significant. Some inorganic P fractions (Pi -NaOH) peaked while the organic fractions (Po -NaOH) fell and vice versa. Leaf litterfall production and leaf litterfall P input peaked around two months following the wettest month. Leaf litterfall P input was a significant predictor of Po -NaHCO3 , a bioavailable P fraction. Future studies on P cycling in terrestrial ecosystems should examine the roles played by individual soil P fractions as they cycle asynchronistically and differently across soil types.(AU)

A ciclagem de fósforo (P), mesmo sendo pouco estudada, é importante para o equilíbrio de macronutrientes em ecossistemas de floresta tropical úmida. Como P no solo ocorre em diferentes formas orgânicas e inorgânicas (frações), com diferentes graus de labilidade, supomos que essas frações variam temporalmente entre os diferentes tipos de solo. Além disso, hipotetizamos uma influência direta da serrapilheira no aporte de P no solo. Coletamos amostras de solo e folhas em três tipos de solo em uma floresta tropical na Amazônia central no Brasil durante cinco meses e usamos o método de fracionamento modificado de Hedley para determinar seis frações orgânicas e inorgânicas de P no solo, bem como P total, lábil e residual. As concentrações de P na serrapilheira foram determinadas pelo método de colorimetria. As frações de P inorgânico e orgânico do solo variaram entre os tipos de solo e ao longo dos meses, mas as interações entre tipo de solo e meses foram majoritariamente não significativas. Algumas frações de P inorgânicas (Pi -NaOH) atingiram o pico enquanto as frações orgânicas (Po -NaOH) caíram e vice-versa. A produção de serrapilheira e a entrada de P atingiram o pico por volta de dois meses após o mês mais chuvoso. A entrada de P da serrapilheira foi um preditor significativo de Po -NaHCO3, uma fração de P biodisponível. Futuros estudos sobre a ciclagem de P nos ecossistemas devem examinar o papel desempenhado pelas frações individuais de P no solo, à medida que circulam de forma assíncrona e diferente entre tipos de solo.(AU)

Amphibians of Serra das Torres Natural Monument: a reservoir of biodiversity in the Atlantic Forest of southeastern Brazil / Anfíbios do Monumento Natural Serra das Torres: um reservatório da biodiversidade da Mata Atlântica no sudeste do Brasil

Abstract The Brazilian Atlantic Forest holds a major part of the country's amphibian species richness and high rates of endemism. In this study, we conducted surveys using the Rapid Assessment (RA) method to sample the amphibian fauna of the Serra das Torres Natural Monument (MONAST), an Atlantic Forest remnant in southeastern Brazil. We sampled actively with a 6-10-person team to collect standard samples from 09:00 to 12:00 hours for the daytime period, and from 18:00 to 22:00 hours for the crepuscular/nighttime period, with a total of approximately 1,320 hours of sampling effort. We supplemented these data with 720 hours of passive sampling, using pitfall traps with drift fences (30 bucket-days). We recorded 54 amphibian species (two gymnophionans and 52 anurans), and the species richness estimated by the Bootstrap method indicates that a slightly larger number of species (n = 60) may occur in the study area. The most speciose family was Hylidae (n = 21), followed by Brachycephalidae (n = 8). Overall, 25% of the species (n = 13) were recorded only once (singletons) and 15% (n = 8) only twice (doubletons). Most amphibians recorded in this study (71%, n = 37 species) were restricted to the Atlantic Forest biome, two species (Euparkerella robusta and Luetkenotyphlus fredi) are endemic to the Espírito Santo state, and one of them, the leaf litter species E. robusta, is endemic to the MONAST. Euparkerella robusta is currently listed as Vulnerable by the IUCN and is classified as Critically Endangered in the Espírito Santo State red list, while L. fredi has yet to be evaluated due to its recent description. Thoropa lutzi is currently listed as Endangered (EN) by both the IUCN and in the State list. Nine species are listed as Data Deficient (DD) and populations of 13 species are considered to be declining by the IUCN. We extend the geographical distribution of two anuran species (Hylodes babax and Phasmahyla lisbella) and fill an important gap in the distribution of Siphonops hardyi. Amphibians associated with the forest floor represented 42% of the species richness from MONAST, and 43% of these species inhabit the leaf litter exclusively. Our study revealed that Serra das Torres preserves a considerable diversity of Atlantic Forest amphibians, which reinforces the need for the conservation of this forest remnant.

Resumo A Mata Atlântica brasileira guarda importante porção da riqueza de anfíbios e altas taxas de endemismos. Neste estudo, nós realizamos pesquisas usando o Método de Avaliação Rápida (RA) com o objetivo de inventariar a fauna de anfíbios de um remanescente da Mata Atlântica no sudeste do Brasil, o Monumento Natural Serra das Torres (MONAST). Amostramos ativamente com uma equipe de 6 a 10 pessoas para coletar amostras padronizadas entre 09:00 e 12:00 horas durante o peíodo diurno e entre 18:00 e 22:00 duranto período crepuscular/noturno, totalizando aproximadamente 1320 horas de esforço amostral. Complementamos estes dados com 720 horas de amostragem passiva usando armadilhas de queda com cercas-guia (30 dias de balde). Registramos 54 espécies de anfíbios (dois gimnofionos e 52 anuros) e a riqueza de espécies estimada pelo Bootstrap indicou um número relativamente maior de espécies (n = 60). A família mais especiosa foi Hylidae (n = 21), seguida por Brachycephalidae (n = 8). No geral, 25% das espécies (n = 13) foram registradas apenas uma vez - singletons e 15% (n = 8) apenas duas vezes (doubletons). A maioria dos anfíbios registrados neste estudo (71%, n = 37 espécies) esteve restrita ao bioma Mata Atlântica, duas espécies (Euparkerella robusta e Luetkenotyphlus fredi) são endêmicas do estado do Espírito Santo, sendo uma delas, a espécie de serapilheira E. robusta, endêmica do MONAST. Euparkerella robusta está atualmente listada como Vulnerável pela IUCN e classificada como Criticamente Ameaçada na lista vermelha do estado do Espírito Santo, enquanto L. fredi ainda não foi avaliada devido a sua descrição ser muito recente. Thoropa lutzi está atualmente listada como Ameaçada (EN) pela IUCN e na lista estadual. Nove espécies estão listadas como Deficiente de Dados (DD) e as populações de 13 espécies são consideradas em declínio pela IUCN. Estendemos a distribuição geográfica de duas espécies de anuros (Hylodes babax e Phasmahyla lisbella) e preenchemos uma importante lacuna na distribuição de Siphonops hardyi. Os anfíbios associados ao chão da floresta representaram 42% das espécies do MONAST e 43% destas espécies habitavam exclusivamente a serapilheira. Nosso estudo revelou que a Serra das Torres preserva diversidade considerável de anfíbios da Mata Atlântica, o que reforça a necessidade de conservação desse remanescente florestal.

Taxonomy of the weevil genus Plumolepilius Barrios-Izás amp; Anderson (Coleoptera: Curculionidae: Molytinae: Conotrachelini): new species from Central America.

Seventeen new species of the genus Plumolepilius Barrios-Izás Anderson 2016, are described. Images of habitus and genitalia of both sexes are presented, as well as a dichotomous key for the identification of males and females of the known species of the genus. The species included here are P. andersoni Barrios-Izás, new species (Costa Rica and Panamá), P. antonioi Barrios-Izás, new species (Honduras), P. camuna Barrios-Izás, new species (Nicaragua), P. genieri Barrios-Izás, new species (Honduras), P. guaimacaensis Barrios-Izás, new species (Honduras), P. hectori Barrios-Izás, new species (Costa Rica), P. linaresi Barrios-Izás, new species (Honduras), P. maesi Barrios-Izás, new species (Nicaragua), P. molinai Barrios-Izás, new species (Honduras), P. monzoni Barrios-Izás, new species (Guatemala), P. morronei Barrios-Izás, new species (Honduras), P. nelsoni Barrios-Izás, new species (Honduras), P. nicaraguensis Barrios-Izás, new species (Nicaragua), P. obrienorum Barrios-Izás, new species (Costa Rica), P. solisi Barrios-Izás, new species (Costa Rica), P. velizi Barrios-Izás, new species (Honduras) and P. zarazagai Barrios-Izás, new species (Honduras).

Can differences between continental and insular habitats influence the parasites communities associated with the endemic frog Haddadus binotatus?

Habitats characterized by geographic isolation such as islands have been studied using different organisms as models for understanding the dynamic and insular patterns of biodiversity. Determinants of parasite richness in insular host populations have been conducted mainly with mammals and birds, showing that parasite richness decreases in insular areas. In the present study, we predicted that the type of environment (insular or continental) can influence the richness, diversity and abundance of parasites associated with the endemic frog Haddadus binotatus (Spix, 1824). We sampled frogs in two insular and two mainland fragments to survey their helminth parasites. The total richness was composed of 15 taxa of Nematoda and two of Acanthocephala, and the community composition of the two islands had more similarities between them than the two mainland localities. The insular effect was positive for richness and abundance of helminths, and no significant effect was observed on helminth diversity - even the mean diversity presented high numbers for the islands. We presumed that insular hosts could have lost some parasites in the colonization process when these continental islands were separated from the mainland, approximately 11,000 years ago. However, the high richness and abundance on islands can be explained by an epidemiological argument, which considers high population density due to insularity and other features of the host as factors that increase parasite transmission success among individuals.

Revision of Pseudastenus Bernhauer, synonym with Xenasterides Newton and six new species (Coleoptera, Staphylinidae, Paederinae).

The genus Xenasterides Newton, 2017 is considered here as a junior synonym of Pseudastenus Bernhauer, 1933, both monotypic and Neotropical genera of Paederinae (Staphylinidae). A thorough description of the genus is provided. The species Pseudastenus barretoi Bernhauer, 1933 and P. plaumanni (Bierig, 1939) are redescribed and illustrated, six new species are described, and a dichotomous key is available for species. These new species are: P. amazonicus, P. ferrugineus, P. latus, P. oculatus, P, ribeirocostae, and P. schubarti.

Two new species of the armored spider genus Tetrablemma O. P.-Cambridge, 1873 from northern South America (Araneae: Synspermiata: Tetrablemmidae)

Two new species of the armored spider genus Tetrablemma O. P.-Cambridge, 1873 from Colombia and Venezuela are herein described and illustrated: Tetrablemma tatacoa sp. nov. from Huila department, Colombia and T. mochima sp. nov. from Sucre state, Venezuela. These species represent the second record of the genus in the New World. Specimens of these new species were collected in pristine ecosystems, which suggests a natural Gondwanan distribution of the genus. Additionally, a distribution map of the Tetrablemma species in America is herein included.

A new species of the armored spider genus Caraimatta Lehtinen, 1981 from Colombia (Araneae: Synspermiata: Tetrablemmidae).

A new species of the armored spider genus Caraimatta Lehtinen, 1981 from Colombian Tropical dry forest fragments is described and illustrated: Caraimatta brescoviti sp. nov. (based on male and female) from Bolivar and Sucre departments, representing the first record of the genus from Colombia. Additionally, photographs of Monoblemma muchmorei Shear, 1978 (other tetrablemmid species previously recorded from the country) are given. A map with the known distribution and an identification key for males and females of the Caraimatta species are also included.

Noblella thiuni sp. n., a new (singleton) species of minute terrestrial-breeding frog (Amphibia, Anura, Strabomantidae) from the montane forest of the Amazonian Andes of Puno, Peru.

We describe a new species of minute, terrestrial-breeding frog in the genus Noblella. We collected a single specimen in the leaf litter of primary montane forest (2,225 m a.s.l.) near Thiuni, in the Provice of Carabaya, Department of Puno, in the upper watershed of a tributary of the Inambari River of southern Peru, the same locality where we found the types of Psychrophrynella glauca Catenazzi & Ttito 2018. We placed the new species within Noblella on the basis of molecular data, minute size, and overall morphological resemblance with the type species N. peruviana and other species of Noblella, including having three phalanges on finger IV (as in N. coloma, N. heyeri, N. lynchi, N. madreselva, N. peruviana, and N. pygmaea), and terminal phalanges T-shaped and pointed. Noblella thiuni sp. n. is distinguished from all other species of Noblella by having ventral surfaces of legs bright red, and chest and belly copper reddish with a profusion of silvery spots. The new species further differs from known Peruvian species of Noblella by the combination of the following characters: tympanic membrane absent, eyelids lacking tubercles, dorsal skin finely shagreen, tarsal tubercles or folds absent, three phalanges on Finger IV, tips of digits not expanded, no circumferential grooves on digits, inguinal spots present. The new species has a snout-vent length of 11.0 mm in one adult or subadult male. Our new finding confirms the high levels of endemism and beta diversity of small, terrestrial-breeding frogs inhabiting the moss layers and leaf litter in the montane forests of the Amazonian slopes of the Andes and adjacent moist puna grasslands, and suggests much work remains to be done to properly document this diversity.

Shredder Chironomid Diets Are Influenced by Decomposition Rates of Different Leaf Litter Species.

The diet of shredder chironomid larvae depends on the local and temporal conditions of the food resources. We analysed the gut content of shredder chironomid larvae that colonised the leaf litter of three riparian species: Hedychium coronarium, Pteridium arachnoideum and Magnolia ovata. We hypothesised that the differences in the decomposition rates of leaf litter species influence the consumption of plant tissue by shredder chironomid taxa over time. We incubated perforated bottles with each leaf species within four low-order streams during 1st, 3rd, 7th, 22nd, 36th, 55th and 85th day of exposure. We used an analysis of covariance (ANCOVA) to compare differences in the percentage of AFDM (ash-free dry mass) and AOM (amorphous organic matter) among leaf litter species. To verify differences in the larvae abundance, we used a general linear model, and to test if there were feeding preferences for AFDM and AOM, we used the adapted Paloheimo selectivity index. Magnolia ovata presented a higher quantity of AOM followed by H. coronarium and P. arachnoideum. Pteridium arachnoideum showed a higher AFDM followed by H. coronarium and M. ovata. The larvae abundance was different among plant species and varied significantly with AFDM and AOM quantities. The consumption of plant tissue by shredder chironomid differed temporarily and among riparian species, where facultative or strict shredders showed strong association with different leaf litter species. The amount of AFDM and AOM in plant tissues explained these differences. We highlighted that shredder chironomids displayed an important role as co-participants in the decomposition process.

Tree stem bases are sources of CH4 and N2 O in a tropical forest on upland soil during the dry to wet season transition.

Tropical forests on upland soils are assumed to be a methane (CH4 ) sink and a weak source of nitrous oxide (N2 O), but studies of wetland forests have demonstrated that tree stems can be a substantial source of CH4 , and recent evidence from temperate woodlands suggests that tree stems can also emit N2 O. Here, we measured CH4 and N2 O fluxes from the soil and from tree stems in a semi-evergreen tropical forest on upland soil. To examine the influence of seasonality, soil abiotic conditions and substrate availability (litter inputs) on trace greenhouse gas (GHG) fluxes, we conducted our study during the transition from the dry to the wet season in a long-term litter manipulation experiment in Panama, Central America. Trace GHG fluxes were measured from individual stem bases of two common tree species and from soils beneath the same trees. Soil CH4 fluxes varied from uptake in the dry season to minor emissions in the wet season. Soil N2 O fluxes were negligible during the dry season but increased markedly after the start of the wet season. By contrast, tree stem bases emitted CH4 and N2 O throughout the study. Although we observed no clear effect of litter manipulation on trace GHG fluxes, tree species and litter treatments interacted to influence CH4 fluxes from stems and N2 O fluxes from stems and soil, indicating complex relationships between tree species traits and decomposition processes that can influence trace GHG dynamics. Collectively, our results show that tropical trees can act as conduits for trace GHGs that most likely originate from deeper soil horizons, even when they are growing on upland soils. Coupled with the finding that the soils may be a weaker sink for CH4 than previously thought, our research highlights the need to reappraise trace gas budgets in tropical forests.

Organization of fish assemblages in blackwater Atlantic Forest streams

This study aimed to determine whether fish species occupy different mesohabitats, as defined by specific criteria of substrate types in Atlantic Forest blackwater streams. We sampled fourteen coastal blackwater rivers along the coast of São Paulo State, Brazil, during the low-flow season (June-September/2016). For each stream, we selected three mesohabitat types (sand, leaf-litter and trunks) in a 100 m river stretch. We sampled 41 mesohabitats, 31 of which contained fish, resulting in 15 species. When multivariate analysis of variance (MANOVA) was applied to the mesohabitat abiotic variables, no significant differences were indicated between them. ANOSIM for species density and biomass and Redundancy Analyses (RDAs) for species density, biomass and fish community indexes showed similar patterns of community structure among mesohabitats. Nevertheless, fish biomass, diversity and richness were associated with such unique environmental features as low shading and shallow habitats. The observed dispersion among mesohabitats suggests that these communities are subject to some level of disturbance, which may affect the value of patches as refugia. Thus, the sharing of these mesohabitat patches among species may represent an opportunistic strategy to maximize the use of available resources for these low density populations living in these unique environments.(AU)

O objetivo do estudo foi testar se espécies de peixes ocupam diferentes mesohabitats definidos por critérios específicos de tipos de substrato em riachos de águas pretas de Mata Atlântica. Durante a estação de baixa vazão (junho-setembro/2016), foram amostrados quatorze riachos costeiros de águas pretas no litoral de São Paulo, Brasil. Para cada riacho, selecionamos três tipos de mesohabitats (areia, folhiço e troncos) em um trecho de rio de 100 m. Amostramos 41 mesohabitats, dos quais 31 com peixes, resultando em 15 espécies. A análise de variância multivariada (MANOVA) aplicada às variáveis abióticas dos mesohabitats, não indicou diferenças significativas entre estes. A ANOSIM para densidade de espécies e biomassa e as Análises de Redundância (RDAs) para densidade de espécies, biomassa e índices da comunidade indicaram padrões semelhantes da estrutura da comunidade entre mesohabitats. No entanto, a biomassa, a diversidade e a riqueza de peixes estiveram associadas a características ambientais específicas tais como habitats rasos e sombreados. Os resultados sugerem que estas comunidades estejam sujeitas a certo nível de perturbação, o que afeta o valor dos mesohabitats como refúgios. Assim, a utilização dos diferentes mesohabitats entre as espécies pode representar uma estratégia oportunista para maximizar o uso de recursos por essas populações de baixa densidade que vivem nestes ambientes peculiares.(AU)

Organization of fish assemblages in blackwater Atlantic Forest streams

This study aimed to determine whether fish species occupy different mesohabitats, as defined by specific criteria of substrate types in Atlantic Forest blackwater streams. We sampled fourteen coastal blackwater rivers along the coast of São Paulo State, Brazil, during the low-flow season (June-September/2016). For each stream, we selected three mesohabitat types (sand, leaf-litter and trunks) in a 100 m river stretch. We sampled 41 mesohabitats, 31 of which contained fish, resulting in 15 species. When multivariate analysis of variance (MANOVA) was applied to the mesohabitat abiotic variables, no significant differences were indicated between them. ANOSIM for species density and biomass and Redundancy Analyses (RDAs) for species density, biomass and fish community indexes showed similar patterns of community structure among mesohabitats. Nevertheless, fish biomass, diversity and richness were associated with such unique environmental features as low shading and shallow habitats. The observed dispersion among mesohabitats suggests that these communities are subject to some level of disturbance, which may affect the value of patches as refugia. Thus, the sharing of these mesohabitat patches among species may represent an opportunistic strategy to maximize the use of available resources for these low density populations living in these unique environments.(AU)

O objetivo do estudo foi testar se espécies de peixes ocupam diferentes mesohabitats definidos por critérios específicos de tipos de substrato em riachos de águas pretas de Mata Atlântica. Durante a estação de baixa vazão (junho-setembro/2016), foram amostrados quatorze riachos costeiros de águas pretas no litoral de São Paulo, Brasil. Para cada riacho, selecionamos três tipos de mesohabitats (areia, folhiço e troncos) em um trecho de rio de 100 m. Amostramos 41 mesohabitats, dos quais 31 com peixes, resultando em 15 espécies. A análise de variância multivariada (MANOVA) aplicada às variáveis abióticas dos mesohabitats, não indicou diferenças significativas entre estes. A ANOSIM para densidade de espécies e biomassa e as Análises de Redundância (RDAs) para densidade de espécies, biomassa e índices da comunidade indicaram padrões semelhantes da estrutura da comunidade entre mesohabitats. No entanto, a biomassa, a diversidade e a riqueza de peixes estiveram associadas a características ambientais específicas tais como habitats rasos e sombreados. Os resultados sugerem que estas comunidades estejam sujeitas a certo nível de perturbação, o que afeta o valor dos mesohabitats como refúgios. Assim, a utilização dos diferentes mesohabitats entre as espécies pode representar uma estratégia oportunista para maximizar o uso de recursos por essas populações de baixa densidade que vivem nestes ambientes peculiares.(AU)

Winged ants (Hymenoptera: Formicidae) presence in twigs on the leaf litter of Atlantic Forest / Colônias de formigas (Hymenoptera: Formicidae) com alados em galhos na serapilheira de Floresta Atlântica

Abstract: In the leaf litter, ants have various nesting resources available, such as live or dead trunks, twigs, leaves, fruits and seeds. On the twigs, there are adults and immature individuals, but also the queen and winged. The production of wings requires time and energy from the colony. The objective of this study was to investigate the presence of winged in ant colonies in twigs on the leaf litter. Our prediction is that the richness and abundance of winged in twigs are the greatest in rainy months. We collected all twigs with ants in 552 plots with 16 m2, totaling 8,832 m2 of leaf litter, in areas located in the Brazilian Atlantic Domain. We compared the species richness and the number of colonies with and without winged, as well as the number of winged over a year. In total, we collected 1,521 twigs with colonies belonging to 92 species of ants. The rate of twigs with winged was low, about 12%. In colonies with winged, the total number of twigs, species and amount of winged does not differ between the months considered dry and rainy. The majority of winged species are leaf litter dwellers, such as Linepithema neotropicum, recorded with the highest amount of winged irrespective of the period. Arboreal species colonized 15% of the twigs and, in 1/3 of these species, winged were recorded as part of the composition of the colony. Although winged represent a small percentage of the colony in twigs, our results indicate that this feature is important for the life cycle of 44% of the species that occupy twigs, considering that winged are fundamental for the dispersion of the colony.

Resumo: Na serapilheira as formigas têm disponíveis diversos recursos de nidificação, como troncos e galhos vivos ou mortos, folhas, frutos e sementes. Nos galhos são encontrados indivíduos adultos e imaturos, mas também rainha e alados. A produção de alados exige tempo e energia por parte da colônia. O objetivo deste estudo foi investigar a presença de alados em colônias de formigas em galhos na serapilheira. Nossa hipótese é que a riqueza e abundância de alados em galhos são maiores nos meses chuvosos. Nós coletamos todos os galhos com formigas em 552 parcelas de 16 m2, totalizando 8.832 m2 de serapilheira em áreas localizadas no Domínio Atlântico brasileiro. Comparamos a riqueza de espécies e o número de galhos com e sem alados, bem como o número de alados ao longo de um ano. No total coletamos 1.521 galhos com colônias, pertencentes a 92 espécies de formigas; a taxa de galhos com alados foi baixa, cerca de 12%. Nas colônias com alados, o número total de galhos, espécies e quantidade de alados não diferem entre os meses secos ou chuvosos. A maioria das espécies com alados é habitante da serapilheira, como Linepithema neotropicum, registrada com a maior quantidade de alados, independente do período. Espécies arborícolas colonizaram 15% dos galhos e, em 1/3 dessas espécies, alados foram registrados fazendo parte da composição da colônia. Apesar de os alados representarem uma pequena porcentagem da colônia em galhos, nossos resultados indicam que este recurso é importante para o ciclo de vida de 50% das espécies que os ocupam, considerando que alados são fundamentais para a dispersão da colônia.

The sensory equipment of a sandokanid: An extreme case of tarsal reduction in harvestmen (Arachnida, Opiliones, Laniatores).

The study of sensory structures has the potential to provide insights into the natural history and evolution of animals. The sensory structures of arachnids are usually concentrated on the pedipalps (the tritocerebral appendages) or on the distal podomere (tarsus) of the anterior walking legs, the latter being the case for armored harvestmen (Opiliones, Laniatores). Therefore, modifications of the tarsus could have direct impacts on the sensory equipment of these animals. Using scanning electron microscopy, we investigated the sensory equipment in an extreme case of reduction in tarsal articles in the harvestman Sandokan truncatus (Sandokanidae), which bears a single tarsomere in all legs, and the potential consequences of this reduction. Additionally, we review the literature on the natural history of the family Sandokanidae. Tarsomeres of all legs are equipped with gustatory sensilla, mechanoreceptors, and a pore organ, but wall-pored olfactory sensilla are restricted to tarsi I and II. Tarsi II present a higher density of olfactory sensilla and also putative campaniform sensilla (strain detectors), which indicates a special sensory function of this pair of legs. Other podomeres are covered with shelled sensilla, a probable chemoreceptor previously unreported in Opiliones. Overall, S. truncatus has types of sensilla largely comparable to harvestmen with longer and subdivided tarsi. However, S. truncatus also exhibits extra-tarsal sensory fields of sensilla basiconica (putative thermo-/hygroreceptors) in previously undescribed sites, and the unique pore organs. Our results establish a basis for further research investigating the natural history, as well as the evolutionary correlations and mechanistic causes of the tarsal reduction in this enigmatic lineage.

Plant, fungal, bacterial, and nitrogen interactions in the litter layer of a native Patagonian forest.

Plant-microbial interactions in the litter layer represent one of the most relevant interactions for biogeochemical cycling as litter decomposition is a key first step in carbon and nitrogen turnover. However, our understanding of these interactions in the litter layer remains elusive. In an old-growth mixed Nothofagus forest in Patagonia, we studied the effects of single tree species identity and the mixture of three tree species on the fungal and bacterial composition in the litter layer. We also evaluated the effects of nitrogen (N) addition on these plant-microbial interactions. In addition, we compared the magnitude of stimulation of litter decomposition due to home field advantage (HFA, decomposition occurs more rapidly when litter is placed beneath the plant species from which it had been derived than beneath a different plant species) and N addition that we previously demonstrated in this same forest, and used microbial information to interpret these results. Tree species identity had a strong and significant effect on the composition of fungal communities but not on the bacterial community of the litter layer. The microbial composition of the litter layer under the tree species mixture show an averaged contribution of each single tree species. N addition did not erase the plant species footprint on the fungal community, and neither altered the bacterial community. N addition stimulated litter decomposition as much as HFA for certain tree species, but the mechanisms behind N and HFA stimulation may have differed. Our results suggest that stimulation of decomposition from N addition might have occurred due to increased microbial activity without large changes in microbial community composition, while HFA may have resulted principally from plant species' effects on the litter fungal community. Together, our results suggest that plant-microbial interactions can be an unconsidered driver of litter decomposition in temperate forests.

Andersonoplatus, a new, remarkable leaf litter inhabiting genus of Monoplatina (Coleoptera, Chrysomelidae, Galerucinae, Alticini).

Andersonoplatus, a new genus with 16 new species from Venezuela (A. andersoni, A. bechyneorum, A. castaneus, A. flavus, A. jolyi, A. laculata, A. lagunanegra, A. macubaji, A. merga, A. merida, A. microoculus, A. peck, A. rosalesi, A. sanare, A. saviniae) and Panama (A. baru), is described and illustrated. All the specimens were collected in leaf litter by R. Anderson and S. and J. Peck. Andersonoplatus is compared to Andersonaltica Linzmeier & Konstantinov, Apleuraltica Bechyne, Distigmoptera Blake and Ulrica Scherer.