The prey and predators of Homalopsine snakes

The diets of all South-East Asian water snakes of the subfamily Homalopsinae are reviewed. New diet observations for 10 species of homalopsine snakes are presented. The data on four of these, Cantoria violacea, Enhydris doriea, E. longicauda and Gerarda prevostina represent the first published diet records for these species. The observations for Fordonia leucobalia, Myron richardsonii andEnhydris enhydris represent the first taxonomically detailed diet records for these three species. The records provided for Cerberus rynchops, Enhydris plumbea and Homalopsis buccata add new taxonomic categories to previous records. The records provided for Cerberus rynchops, E. plumbea and Homalopsis buccata add new taxonomic categories to previous records. Four generalities emerge from our findings: (1) freshwater homalopsines feed primarily on fish and the adults and larvae of amphibians; (2) at least four of the eight estuarial species specialize on crustaceans while two primarily prey on fish; (3) feeding on crustaceans appears to have evolved independently at least twice; (4) prey are usually less than 10% of the predator's mass. The known predators of homalopsines are summarized and include both invertebrates and vertebrates. The microhabitats of the estuarial species are discussed and related to prey and habitat preferences.     

Diverse plant taxa used by arboreal succineid snails as microhabitats

Arboreal species of the family Succineidae (Gastropoda: Pulmonata) eat fungi, algae and diatoms and use plants as microhabitats. However, the specific plant taxa that arboreal succineids use have not been thoroughly examined. In this study, plant species used as microhabitats by two succineid species, Boninosuccinea ogasawarae (Pilsbry) and Boninosuccinea punctulispira (Pilsbry), were examined on the oceanic Ogasawara (Bonin) Islands in the western Pacific Ocean. Boninosuccinea ogasawarae and B. punctulispira were recorded on 23 (four introduced and 19 native) and 37 (four introduced and 33 native) plant species, respectively. More individuals of B. ogasawarae and B. punctulispira were found on abundant plant species than on rare plant species. No significant difference in snail density was found between the introduced (Bischofia javanica) and native (Ardisia sieboldii) tree species. Therefore B. ogasawarae and B. punctulispira may use introduced plants as well as native plants as microhabitats.     

Life history of the spider Selenops occultus Mello‐Leitão (Araneae,Selenopidae) from Brazil with notes on the natural history of the genus

Selenopids are extremely fast‐moving, dorsoventrally flattened spiders and are among the most secretive of animals. However, they can be locally abundant, providing an opportunity to examine their life and natural histories. Here we report life history data from Selenops occultus which were studied and collected monthly for over a year at an experimental farm of São Paulo State University in Botucatu, Brazil. We compare these data with what we have found in other Selenops species in the Caribbean region. Overall, S. occultus showed considerable seasonality. Males were most common in January and March, whereas females were more common in June and November. Significant differences between the numbers of males collected during the wet and dry seasons indicate that mating may be limited to the wet season. The Caribbean species share similar natural histories to S. occultus, such as little conflict in small areas and overlapping generations throughout the year.     

Arboreality predicts Batrachochytrium dendrobatidis infection level in tropical direct-developing frogs

Pathogen-mediated changes in host behaviour can result from hosts altering their habitat preferences. Although infection risk with pathogenic fungus Batrachochytrium dendrobatidis in amphibians is associated with environments favouring its growth, the relationship with microhabitat use has not been examined. Here, we aim to determine if microhabitats used by frogs during their nocturnal activity predict B. dendrobatidis prevalence and infection intensity. Our focal host, Eleutherodactylus coqui, is a habitat generalist that uses multiple habitats from the forest floor to the canopy. We analysed data on B. dendrobatidis occurrence in 157 adults and 122 juveniles at El Yunque National forest in Puerto Rico. We categorized each individual’s nocturnal microhabitat as forest floor, curled palm fronds in the floor, arboreal bromeliads and foliage or tree trunks 50 cm to 2.5 m above ground. We found that frogs on the forest floor had the greatest B. dendrobatidis prevalence (73%), compared with those active in vegetation above ground (55%). Overall, the probability of B. dendrobatidis infection in frogs using microhabitats on the forest floor was twice as great as for those on arboreal substrates. Differences in B. dendrobatidis prevalence and intensity in E. coqui may be explained by specific abiotic conditions of microenvironments (temperature and humidity) affecting both pathogen and host, and by the age-specific ecological requirements of hosts. Adults were found to be most active in microhabitats where individuals had lower infection burdens, suggesting pathogen-modulated habitat choice. This work has important implications for the evolutionary dynamics of enzootic diseases and provides data that may inform potential mitigation strategies against a generalist amphibian pathogen.     

Cryptic and non-cryptic diversity in New Guinea ground snakes of the genus Stegonotus Duméril,Bibron and Duméril, 1854: a description of four new species (Squamata: Colubridae)

ABSTRACT

The island of New Guinea has been identified as biologically megadiverse but many taxa are still poorly known. This is especially the case for many of the island’s snakes, which by their very nature can be difficult to collect and study. Here we examine the phylogenetic and phylogeographic structure of a poorly studied snake genus, Stegonotus, focusing on the species of New Guinea; until now, Stegonotus has never been examined using modern phylogenetic methods. Using molecular data from 49 individuals representing eight of the ten described species, and including all New Guinea taxa, we estimate a multilocus phylogeny and examine population structure to help identify undescribed taxa. We use morphological data from the corresponding museum vouchered specimens (where available) and also examine additional specimens for taxa not included in the molecular data set to determine morphological differences among putative taxa. We find molecular evidence for four new species of Stegonotus, both morphologically obvious and cryptic, and describe them herein. The recognition of these four species indicates that Stegonotus diversity has been previously underestimated and also suggests that there are likely additional undescribed taxa within the genus. These four taxa increase the number of described species by 40% and further confirm New Guinea as the centre of diversity for the genus.

www.zoobank.org/urn:lsid:zoobank.org:pub:9E21390E-3FD4-40EB-9442-31BC92A76B4F     

Aspects of natural history in a sand boa,Eryx muelleri (Erycidae) from arid savannahs in Burkina Faso,Togo, and Nigeria (West Africa)

The ecology of West African arid savannah snakes is still poorly known, especially in regard to the fossorial species. Here, field data on distribution, morphometrics, habitat use and diet are reported for the sand boa Eryx muelleri (Erycidae) from three different countries, i.e. Burkina Faso, Togo and Nigeria. This snake was observed in 21 distinct localities, and a total of 39 individuals was recorded. The species is likely fairly common and locally abundant. Mean body length of snakes was similar among countries and between sexes, but males had proportionately longer tails than females. Body length was significantly positively correlated with both tail length and head length. Adult sex ratio was close to parity. Most of the specimens were found in well-vegetated spots with low percentage of bare soil. There were apparently both ontogenetic and intersexual dietary variations: (1) a single analysed juvenile fed upon a small-sized lizard, whereas adults fed considerably upon young rodents; and (2) females fed exclusively upon young rodents and males upon both lizards and young rodents. In conservation terms, the species is actively exported from Togo for the pet trade, and additional individuals may also be illegally collected in other countries.     

Food niche of Exomalopsis (Exomalopsis) fulvofasciata Smith (Hymenoptera: Apidae) in Brazilian savannah: the importance of oil-producing plant species as pollen sources

Exomalopsis are ground-nesting species, and their food-niche breadth is little known due the difficulty in locating the nests and finding efficient bait plants to attract these bees. Some species of Exomalopsis were recorded as tomato, hot pepper and eggplant pollinators. Information about the food niche could be useful to increase Exomalopsis populations, providing consistent and comparable data for the enrichment of natural and crop areas with adequate plant sources. This study aimed to determine the food niche and the role of pollen size in the diet of E. fulvofasciata. We analysed pollen loads of 28 individuals of E. fulvofasciata collected from bait plants, in two natural areas of the Brazilian savannah. Only five pollen types belonging to the families Malpighiaceae, Solanaceae, Leguminosae, Myrtaceae and Lythraceae were important for this species. This result indicates that E. fulvofasciata is probably a polylectic species. However, we noticed that the Byrsonima used as bait plants contribute significantly for its larval provision, indicating that small pollen grains were more frequently collected.     

Breeding preferences in the treefrogs Dryophytes japonicus (Hylidae) in Mongolia

ABSTRACT

When a species occurs over a broad range of climates and landscapes, the breeding ecology of that species is expected to vary locally. Additionally, a basic knowledge of breeding ecology is required before other types of studies may be conducted, such as physiology or conservation. In North East Asia, Dryophytes japonicus is distributed from Japan to Mongolia, where its breeding ecology is unknown. The objectives of this study were to understand the breeding requirements of D. japonicus in this part of its range. We collected data for Dryophytes japonicus at 56 sites located within 23 independent localities in Northern Mongolia during the breeding season 2017. The data collected included habitat type and co-occurring amphibian, fishes and bird species. Our results show that the species prefers circa 70 m long oxbow lakes for breeding, while habitat characteristics, water quality and co-occurring species were not significantly associated with the occurrence of the species. We therefore conclude that D. japonicus is behaviourally plastic in Mongolia, as it is in other portions of its range, and that the species can use several types of environments and co-occur with different species at its breeding sites. Corvus dauuricus was the only bird species significant predicting the occurrence of D. japonicus, likely because of overlapping ecological preferences.     

Specialist and generalist species in habitat use: implications for conservation assessment in snakes

Habitat specialization is recorded as one of the central factors that make species vulnerable to extinction. Among snakes, there is considerable variation in this trait, as some species are specialists and others are generalists in habitat use. We have quantified habitat specialization in the snakes of the southern Iberian Peninsula, and compared it with their abundance and IUCN categories. All data were combined for a principal components analysis that discriminated two main groups: three generalist species that live in all types of habitat, and five specialist species that ranged from rather scarce to extremely rare and are found only in unaltered habitats. The three generalist snakes are not threatened and their IUCN category is Least Concern. Three out of the five specialist species are categorized as Near Threatened, Vulnerable, and Endangered at regional or national levels. The other two species are currently considered Not Threatened and we discuss whether they are incorrectly classified. The conservation status of snakes is difficult to evaluate because of their secretive habits and low population densities. We suggest that quantifying habitat specialization may be a useful tool for assessing the conservation status of secretive organisms such as snakes.     

Spatial niche variation in two sympatric species of Bokermannohyla (Anura: Hylidae) in southeastern Brazil

We studied patterns of microhabitat use by adults of two sympatric Bokermannohyla species at the Reserva Particular do Patrimônio Natural Santuário do Caraça, southeastern Brazil. We selected three streams, one where both species occurred in syntopy and the other two where each one occurred alone. We sampled 150-m transects in each stream throughout 1 year, recording microhabitat features for each frog located (substrate type, height and distance from water). Microhabitat availability varied between dry and wet seasons in all streams, and overall microhabitat diversity changed in two streams. Bokermannohyla nanuzae seemed to have a niche contraction in the presence of Bokermannohyla martinsi, but this only happened during the dry season. Microhabitat requirements during the wet season may be closely linked to similar reproductive needs that probably represent a strong selective pressure, forcing niche overlap.     

The social wasps (Hymenoptera: Vespidae: Polistinae) of a fragment of Atlantic Forest in southern Bahia,Brazil

The Atlantic Forest is one of the most threatened ecosystems in Brazil, with only 22% of its original coverage remaining. Despite around 900 species of Polistinae being described worldwide and their being widely distributed in the Neotropical region, they are still poorly known in northeastern Brazil, especially in Atlantic Forest. The aim of this work was a survey of social wasps in three fragments of Atlantic Forest with differences in the level of regeneration and in the physiognomy, performed at Michelin Ecological Reserve (located in Igrapiúna, southern Bahia State, Brazil) and employing three methodologies – attractive solution, Malaise trap and light trap ‘Luiz de Queiroz’ – for 12 months in transects. A total of 1066 specimens, belonging to 29 species from nine genera, were collected in the reserve. Epiponini was the richest tribe (23 species) followed by Mischocyttarini (five species) and Polistini (one species). The Malaise trap was not efficient during the night, having a deficit of 5110 hours; the only nocturnal genus, Apoica, was collected with a light trap – an attractive solution that was more efficient. Once it was left for 12 discontinuous days (72 hours), showing that more than one methodology is desirable for wasp surveys. Latitudinal analysis comparing the study area with other areas grouped the Michelin Ecological Reserve with areas in southeastern Brazil, which may be related to a lack of standardization in collecting methods. This study presented the highest richness in this region.     

Spatial and temporal organization in three syntopic species of the Scinax ruber group (Anura: Hylidae) in the Atlantic rainforest,southeastern Brazil

Coexistence of anuran species might lead to acoustic interference among communications, especially where species are closely related. This problem might be minimized through resource partitioning. To test this idea, we analysed calling with respect to temporal and physical space usage in three syntopic, closely related species (Scinax cuspidatus, Scinax aff. hayii and Scinax aff. x-signatus) in a temporary pond in the Atlantic rainforest. The chorus attendance of each species resulted from a different combination of factors in the rainy season. Although there was some temporal overlap of daily activity among species, peak activity time differed, particularly between the two species whose calls were most similar. Although all three species tend to aggregate in open microhabitats, their coexistence is apparently facilitated by differential use of vertical strata and organization of calling sites near the sites of conspecifics. Together, these factors apparently reduce acoustic interference among heterospecific calls.     

Reproductive patterns of Trachycephalus venulosus (Laurenti, 1768) and Scinax fuscovarius (Lutz, 1925) from the Cerrado,Central Brazil

Animal mating systems are moulded by ecological factors, mainly the temporal patterns of reproduction. We report the reproductive period, use of microhabitats, clutch and egg sizes, reproductive efforts, occurrence of sexual size dimorphism, and the relation between body size and fecundity in the gravid females of Trachycephalus venulosus and Scinax fuscovarius at Serra da Bodoquena, Central Brazil. The reproduction of both species was correlated with the rainy season. Females of T. venulosus produced more eggs and their eggs were larger than those of S. fuscovarius. The females of both species were larger and heavier than males. The reproductive effort was measured as the ratio of gonad mass in relation to body mass. Females of both species presented similar reproductive efforts, but males of S. fuscovarius invested more in gonads compared to males of T. venulosus. Trachycephalus venulosus presented significant correlation between snout–vent length versus number of mature eggs and body mass versus number of mature eggs and ovarian mass. Scinax fuscovarius showed significant correlation between body mass versus ovarian mass. Trachycephalus venulosus is an explosive breeder, whereas S. fuscovarius has prolonged reproduction. These species are able to adapt to several types of habitat, due to behavioural and physiological plasticity.     

Orb‐web spiders (Araneae: Araneomorphae; Orbiculariae) captured by hunting‐wasps (Hymenoptera: Sphecidae) in an area of Atlantic Forest in south‐eastern Brazil

Members of two hunting‐wasp families, Pompilidae and Sphecidae, are among the major predators of orb‐web spiders. In this study, we collected paralysed spiders from natural nests and trap‐nests provisioned by sphecids in an area of Brazilian Atlantic Forest, and compared these data with the composition of species collected by visual searching during one year. Prey preferences were analysed based on the relative abundance of spider species, their size and web characteristics. We also compiled a list of orb‐weavers captured by four sphecid genera reported in 40 other studies. A large number of prey was obtained from natural nests of Trypoxylon (Trypargilum) albonigrum in Parque Estadual Intervales, especially species of Eustala, Parawixia, and Araneus (Araneidae). Other prey, stored in trap‐nests by T. lactitarse and unidentified hunting‐wasp species, included Nephila (Tetragnathidae), Parawixia, Ocrepeira, Mecynogea, Acacesia (Araneidae), and other spider species that were less abundant. All the species that were heavily preyed upon had a relatively lower abundance in our samples of prey availability. The range of body sizes of spiders captured by Trypoxylon in our study area include the size of some abundant orb‐weavers always absent in their nests. These results indicate that factors other than abundance in the field and the spider's size influence prey selection or susceptibility to attack.     

A herpetological survey of the Kathmandu Valley,Nepal, and phylogenetic identification of Megophrys (Xenophrys) zhangi

ABSTRACT

The herpetofauna of Nepal have been historically understudied, and although previous studies have reported on bioinventory surveys of the Kathmandu Valley, few have surveyed widely during the peak monsoon season. In addition, past studies largely neglected to survey intact forest habitats. Here we conduct a comprehensive field survey of the herpetofauna of the Kathmandu Valley, Nepal, with an emphasis on the surrounding foothills containing intact forest habitat. We record natural history and distribution data for seven species of amphibians and four species of reptiles. We also use mitochondrial sequence data to confirm the phylogenetic placement of two frog species, Megophrys (Xenophrys) parva and Duttaphrynus melanostictus. Using phylogenetic and morphological data we assign Megophrys parva from the Kathmandu Valley to Megophrys zhangi. We find that while this species shares a haplotype with its sister species, Megophrys monticola, morphological data align the individuals from the Kathmandu Valley with M. zhangi from Tibet. We find that M. zhangi exhibits no phylogenetic structure within the Kathmandu Valley, and wider sampling is needed throughout the Himalayas to determine its full range. These findings support the hypothesis that molecular sequence data will lead to the discovery of cryptic species in Nepal and facilitate the revision of species taxonomy.     

Habitat use and diet of the endemic lizard Ameivula nigrigula (Squamata: Teiidae) in Caatinga domain,Northeastern Brazil

ABSTRACT

The lizard Ameivula nigrigula is endemic to Caatinga vegetation and the transition zone between the Caatinga and Cerrado domains in Brazil. It was recently described, but little is known about its biology. We analysed microhabitat use and the diet of this species in Caatinga vegetation in Santo Inácio, Bahia State. Its diet consisted mainly of arthropods and plant material, and in particular aggregate (e.g. termites) and large preys (e.g. Coleoptera, insect larvae and spiders), reflecting their nutritional and energy values and high water contents. With regard to habitat use, we found A. nigrigula using microhabitats with tall vegetation over accumulated leaf litter, which could potentially contribute to temperature regulation. Together, those characteristics contribute to the survival of lizards in environments with low water availability and high temperatures, such as the Caatinga domain.     

Microhabitat use by the white‐clawed crayfish in a Tuscan stream

Habitat modification, pollution, overfishing, poaching, competition from non‐indigenous species, and diseases have led to the extinction in Europe of many populations of indigenous crayfish. Under the rationale that any programme of reintroduction should be preceded by a thorough understanding of habitat requirements of the species of concern, we studied the microhabitat use of an Austropotamobius pallipes population in Tuscany, central Italy. Microhabitat use was assessed for water depth, current velocity, substrate, percentages of boulders, underwater tree roots, and in‐stream vegetation cover. Results show that A. pallipes' habitat use is size‐partitioned. Smaller individuals mostly occupy stream edges in shallow waters with submerged roots, whereas larger individuals use deeper waters, often associated with boulders. Crayfish spatial distribution is restricted mostly to the microhabitats characterised by extensive cover and slow current velocity. The study highlights the importance of habitat heterogeneity and cover elements for the protection of this indigenous species.     

Abundance and ecologic distribution of the shrimp Rimapenaeus constrictus (Crustacea: Penaeidae) on the northern coast of São Paulo State,Brazil

The abundance and ecologic distribution of the shrimp R. constrictus were compared among three different embayments within the northern coast of São Paulo State (23°S, 45°W); i.e. Mar Virado (MV), Ubatuba (UBA) and Ubatumirim (UBM). Key environmental factors were monitored for a better understanding of the distributional patterns of this species, namely temperature, salinity, depth, organic matter content and texture of sediments. In each bay, six transects were delimited, four parallel to the coastline and the other two in areas adjacent to rocky shores. Monthly samples were taken over a 2-year period (1998 and 1999), using a shrimp fishing boat equipped with double-rig nets. Abundance data were treated separately according to environmental characteristics. A total of 4978 specimens was obtained; 921 at MV, 1948 at UBA and 2109 at UBM. The spatial distribution of R. constrictus differed among bays. Higher abundance values were recorded at areas where silt and clay comprised less than 70% of the sediment. A more diversified sediment at UBM and UBA apparently favours the establishment of this species in the region. Its abundance also followed a seasonal trend, higher during spring and summer when intrusions of cold South Atlantic Coastal Waters (SACW) are frequent, promoting the migration of this shrimp to more sheltered areas. These results suggest that sediment type and temperature are the most important variables affecting the spatial and seasonal distribution of this species.     

Natural history and ecological niche modelling of coastal Atyphella Olliff Larvae (Lampyridae: Luciolinae) in Vanuatu

ABSTRACT

The genus Atyphella Olliff includes several coastal species with larvae that were collected on coastal rock within the intertidal zone. Recent fieldwork in Vanuatu has expanded the distribution of these insects and begun to provide insight into how they are able to survive in such a unique environment. An ecological niche model is produced using Maxent to predict additional locations of coastal Atyphella in the South Pacific. Larval instars for the two species of Atyphella in Vanuatu are estimated using protergum shield width measurements. Additionally, submersion tests were performed on larvae to determine survivability in saltwater and freshwater environments. These data provide evidence for previously unknown aspects of their natural history that strongly suggest the species are multivoltine and spend a large portion of their larval stage in the intertidal zone.