Population status of the American crocodile, Crocodylus acutus (Reptilia: Crocodylidae) and the spectacled caiman, Caiman crocodilus (Reptilia: Alligatoridae) in the Costa Rican North Caribbean

Along the Costa Rican Caribbean shoreline, it is possible to find two species of crocodilians, the American crocodile (Crocodylus acutus) and the spectacled caiman (Caiman crocodilus). This region can be divided geographically into three subregions: North, Central, and South Caribbean. We conducted this research in the North Caribbean, between October 6, 2018 and August 31, 2019. Specifically, we worked in the area lying between the Jalova Station of the Tortugero National Park (TNP) and Agua Dulce Lake situated in the northern tip of Machuca Island, at the mouth of the Colorado River inside the Barra del Colorado National Wildlife Refuge (BACORE), which includes other connecting wetlands as well (Sierpe River, Samay Lake). Overall, this study area had an approximate extension of 408 km2 characterized by large, wide and deep canals, as well as wetlands, meanders, and adjacent lakes. The sampling was performed along 10 segments that varied in length from 7.5 km up to 29.49 km, located in the nearby zones of TNP and BACORE. In these zones, nightly counts were carried out using dazzling lamps. Individuals of C. acutus and C. crocodilus were classified into eight and six body size classes, respectively (both with 50 cm intervals). A relative abundance of 0.55 crocodiles and 1.37 caimans per linear kilometer was estimated during these spotlight surveys. The capture of 39 caimans let us to estimate a ratio of 30 males to 9 females (3.3:1 M:F). In stark contrast, only 1 male and 1 female crocodile were captured. A total of 85 C. acutus and 205 C. crocodilus were observed. Regarding the number of caiman sightings in the TNP, a statistically significant difference was found (Χ2=5.62, p≤0.05) for the distribution by sizes between the zones of BACORE and TNP, whereas no such difference was found for C. crocodilus sightings (Z=–1.22, p≥0.222). Some segments had a higher probability of caiman occurrence than did others in the surveys performed during the monitoring period (X2=8.36, p≤0.05), especially the Jalova-Sierpe River, Caño Negro-Tortuguero, and Tortuguero-Samay Lake (Tortuguero subarea) segments. Ninety percent of the sightings occurred in the BACORE zone, and this was significantly different (Χ2=7.34, p≤0.026) from the studied subareas. The number of crocodile sightings in the Colorado River segment was significantly different and higher than the other segments (X2=7.28, p≤0.05). There was a significant statistical difference among the sizes in all areas of study (X2=5.529, p≤0.026). The abundance of C. acutus and C. crocodilus in the north Caribbean part is lower than in the central Caribbean part of Costa Rica, where this species could use the resources available in more urbanized areas.

Small mammal assemblages and their ectoparasite prevalence (Acarina) in mangrove forests of Peninsular Malaysia

The mangrove forest is located in the coastal intertidal zone and plays a vital role in buffering against erosion from storm surges, currents, waves, and tides. This ecosystem also serves for ecotourism due to its heterogeneous habitats, which supported a high diversity of plants and animals. Small mammals are among the abundant but poorly recognised inhabitants in mangrove forests. Apart from their role as primary consumer and prey, they are host to various ectoparasites, which potentially become the primary vector for tick-borne diseases among visitors. Therefore, this study aims to determine the small mammal assemblages and their ectoparasite prevalence in mangroves forests of Peninsular Malaysia. The capture-release method was applied for small mammal sampling, and each captured individual was screened and collected for ectoparasites before released. DNA barcoding using CO1 genes was performed for small mammal species verification, whereby ectoparasite identification was based on morphological identification and molecular verification using 16S rDNA genes. A total of 94 small mammals from 6 species were captured across sites, dominated by Rattus tiomanicus (n=74). From this number, 15 individuals (16% prevalence) were infested by ticks, 22 individuals (23%) were infested by mites, whereas 4 individuals (4%) were infested by both ticks and mites. Five species of ticks and one mite species were identified; Amblyomma cordiferum, Ixodes granulatus, Haemaphysalis hystricis, Dermacentor auratus, Dermacentor atrosignatus, and Laelaps echidninus. This study reveals a relatively poor diversity of small mammals in the mangroves forest, of which highly infested with a diversity of ectoparasites, elucidating the relationship of hostectoparasite associations in the riparian zone. This information is crucial to inform visitors to these areas, ultimately safeguard against ectoparasite-borne disease.

Evaluation of the reproductive parameters of female neotropical migratory fish from a lotic and lentic environment of a dammed river

The fragmentation of watercourses caused by dams is considered to be one of the main threats to aquatic biodiversity worldwide, especially for ichthyofauna. Several studies have shown that the environmental modifications caused by dammed water bodies can change the various reproductive parameters of freshwater fish. Therefore, the present study aims to comparatively analyze the reproductive potential of female Megaleporinus reinhardti, a migratory species, sampled in the lentic environment of the Três Marias Reservoir and the lotic environment of the São Francisco River. Biometric data were obtained from 79 females and the biological indices were subsequently calculated. Additionally, the microscopic analysis of the gonads was performed, and the follicular atresia index was compared. The results of the study show that fish from the lotic environment presented higher gonadal volume, fecundity, and oocyte diameter, and a lower follicular atresia index when compared to fish from the lentic environment. In summary, the data suggest that environmental changes, i.e. from a lotic to lentic environment, caused by river damming, may negatively affect the reproductive process of migratory fish, such as M. reinhardti, and impair the maintenance of the population of this species in lentic environments

Ecological characterization of mosquitoes (Diptera: Culicidae) in areas of the Mato Grosso Pantanal, Mato Grosso State, Brazil

Bimonthly diurnal and nocturnal captures were conducted in four different sampling sites of the Mato Grosso Pantanal region over 24 consecutive months between March 2009 and January 2011. The goal of performing these collections was to elucidate aspects of the biology and ecology of mosquitoes in this region since little to nothing is known about these aspects for many species. A total of 17,532 specimens were captured, comprising two subfamilies, nine genera, and 44 species. The main species of culicids found in the Mato Grosso Pantanal had strong ecological compatibility with well-preserved environments and with some of the specific habitats found in at least one of the four selected collection sampling sites. Anopheles darlingi, An. albitarsis, and An. triannulatus are well-suited to environments with large water bodies and greater anthropic activity. Culex nigripalpus and Cx. quinquefasciatus prefer environments with bush fragments and pronounced human action and movement. Culex declarator and Psorophora albigenu, the most eclectic, prefer wild areas and with some anthropic activity. Mansonia titillans is associated with environments offering a wide variety of natural breeding areas that enable its development, in particular natural swamp areas covered with macrophytes, which is one of the natural components of the Pantanal biome. The effect of the flooding season on the population density of anophelines is especially advantageous, with an explosion in the number of individuals in periods of widespread flooding. The region’s environmental dynamics are regulated by flooding cycles with alternating periods of flooding and drought, which are the main factors governing the ecology of the local fauna and flora. Flooding periods contribute to raising culicid species’ richness and diversity, while the droughts result in a more even distribution of specimens within species. The flooding season of the Pantanal occurs between November and May and coincides with the greatest abundance of culicid species. During this period, the human population of the region has greater contact with mosquito vectors carrying pathogens, including arboviruses, which previous studies have confirmed via seropositivity in the region’s equines and birds.

New species and records of Exalloniscus Stebbing, 1911 from southern Asia (Malacostraca, Isopoda, Oniscidea)

The genus Exalloniscus is widely distributed in southern and eastern Asia. In this contribution, eight species are described as new: Exalloniscus schmalfussi from Nepal; E. siamensis from Thailand; E. kampucheaensis from Cambodia; E. tortilis and E. deharvengi from Vietnam; E. stilifer from southern China; E. burmaensis from Myanmar; and E. convexus from Laos. Ten more species are recorded: E. nepalensis from Nepal; E. coecus, E. brincki, E. bicoloratus, E. caudatus and E. maschwitzi from West Malaysia; E. sumatranus from Sumatra, Indonesia, and Singapore; E. papillosus from West Malaysia and Vietnam; and E. thailandensis from Laos. Exalloniscus bessoni Dalens, 1992 and E. yinae Nunomura & Xie, 2000 are considered to be junior synonyms of E. thailandensis Dalens, 1987. A map with the recorded distributions of all the 28 species of Exalloniscus is provided and their habitat is discussed.

Blessing the rains down in Africa: spatiotemporal behaviour of the crested porcupine Hystrix cristata (Mammalia: Rodentia) in the rainy and dry seasons, in the African savannah

The assessment of habitat selection and temporal patterns of activity rhythms is paramount for wildlife conservation. Studies on behavioural ecology of wild mammals are particularly challenging in tropical areas, mostly when involving rare or elusive species. Despite being a common species in Italy, the crested porcupine Hystrix cristata is threatened of extinction throughout most of its sub-Saharan range. All available information on the ecology of this species has been collected in Italy, whereas no data is present in the scientific literature on spatiotemporal behaviour of this large rodent in Africa. In this work, we attempted to determine habitat selection and temporal patterns of activity rhythms of the crested porcupine in northern Benin and neighbouring countries, through intensive camera-trapping. We collected a total of 146 records of crested porcupine, 91 in the dry season (October-March) and 55 in the rainy season (April-September). Porcupines used most habitats in proportion to their local availability, while selecting rock outcrop formations (possibly used as shelter sites) and avoiding open areas, wetlands and gallery forests. A mostly nocturnal behaviour was confirmed throughout the year, with some diurnal activity at the start and at the end of the rainy season. The importance of rains in determining birth peak has been also showed, with juvenile individuals always observed at the start and at the end of the rainy season. Full moon always inhibited activity of this large rodent, most likely evolved as an antipredatory behaviour to limit encounters with potential predators (common leopard Panthera pardus, spotted hyaena Crocuta crocuta and honey badger Mellivora capensis) and humans. Poaching pressure towards porcupines in West Africa is strong. Porcupines are killed for the traditional medicine, for their meat and because they are widely considered as a crop pest. This assessment should therefore be used as a basic tool to design conservation plans to preserve this rodent species in its native range.

Physical factors at salt licks influenced the frequency of wildlife visitation in the Malaysian tropical rainforest

Mineral reservoirs or salt licks are commonly used by wildlife to regulate the concentration of salt and minerals in their bodies. Salt lick utilisation is known to be influenced by the chemical composition, but information on their physical properties, particularly vegetation surrounding the salt licks is scarce. In this study, physical factors and wildlife utilisation at two natural salt licks (SPU and SPS) located in Perak, Malaysia, were determined. Wildlife visitation data were retrieved from camera traps. SPU exhibits two reservoirs represented by rocky and clay substrate, with minimally dense vegetation dominated by hardwood species and climbers. SPS encompasses muddy topsoil, open canopy cover, with highly dense forest floor vegetation. The wildlife survey shows a higher frequency of visitation in SPS, especially by ungulates, potentially due to dense understorey foliage that provides foraging sites for these animals. SPU exhibits more diverse but less frequent wildlife species, particularly primates, carnivores, and avian groups. High emergence and closed canopy cover at this lick serve as perching sites for primates and birds, while less dense understory vegetation could aid in prey detection among carnivore. Regardless of their physical assemblages, salt licks are an essential local hotspot for wildlife, therefore, elucidating the need to prioritise conservation areas by maximising the complementarities of salt licks.

Morphology, development and reproduction of Atractomorpha acutipennis (Guérin-Méneville, 1844) (Orthoptera: Pyrgomorphidae)

For a better knowledge of Atractomorpha acutipennis bio-ecology and to facilitate its identification, we studied the morphology, development and reproduction of this grasshopper on Manihot esculenta under laboratory conditions. Five hundred and fifty-one first nymphal stages obtained in the laboratory were reared in cages. Some body parts allowed a clear identification of different nymphal instars. Post-embryonic development passed through six stages (males) and seven stages (females). Mean nymphal development time was 17.14 ± 0.62, 12.91 ± 0.62, 13.45 ± 0.69, 13.80 ± 0.68, 15.23 ± 0.55 days respectively in males nymphal instars 1 to 5 and 16.18 ± 0.54, 13.13 ± 0.59, 12.49 ± 0.42, 13.19 ± 0.58, 14.58 ± 0.61, 16.57 ± 0.68 days respectively, in females nymphal instars 1 to 6. Adult females deposited an average of 3.67 ± 2 egg pods each comprising 30.77 ± 10.5 eggs. First mating was observed 18 ± 15.42 days after the last moult. Oviposition occured on average 19.33± 5.33 days after the first mating. This study provides important information about the biology of A. acutipennis, which could help in developing control methods against this grasshopper in southern Cameroon.

Unravelling taxonomic ambiguity of the Mastacembelidae in the Mekong Delta (Vietnam) through DNA barcoding and morphological approaches

Morphological-based species identification can be problematic for a comparative worldwide survey if taxonomic keys are limited and inconsistent, as illustrated in the family Mastacembelidae. This study combined DNA barcoding and morphological methods to test species identification of Mastacembelidae in the Mekong Delta with emphasis on taxonomic ambiguity of the precise identification of the fish locally known as chach bong. Fish specimens were collected from fishermen in different regions of the delta. Five presumed species within two genera were recorded. Samples were morphologically measured for morphometric and meristic traits. Representative samples of each species were sequenced at the cytochrome c oxidase subunit I (COI) gene. The number of dorsal fin spines and general morphological appearance are distinguishable among the five presumed species. However, morphometric measurements overlapped between Macrognathus semiocellatus and Macrognathus siamensis. K2P distances based on COI sequences among species were high, ranging from 12.4% to 18.7%. All individuals were separated into monophyletic groups of species, clustered into Mastacembelus and two Macrognathus lineages. Chach bong should be recognized as Mastacembelus favus and not Mastacembelus armatus as previously classified. No Mastacembelus armatus was recorded in the Mekong Delta. GenBank sequences of Mastacembelus armatus formed a sister relationship to Mastacembelus favus although both have the same range of number of dorsal fin spines and similar reticulated patterns on the body. Misidentification between these two species has been widely recorded in international databases of species taxonomy and DNA barcodes. Nonetheless, their genetic distance (12.4%) is higher than conspecific distances of samples from other regions, indicating the two species can be differentiated by DNA barcoding.

The first detection of a population of Aedes aegypti in the Atlantic Forest in the state of Rio de Janeiro, Brazil

Aedes aegypti is almost completely restricted to human-modified environments, especially urban areas, and rarely invades forests. Ovitraps were utilized in a reserve (Bom Retiro) in Rio de Janeiro state. Eggs of A. aegypti, genetically not differentiable from those of urban mosquitoes, were obtained at a location more than 700 m inside the border of the forest and 900 m away from a trail at the entrance to the forest. The presence of A. aegypti in a primary forest indicates its ability to adapt to sylvatic environments in Brazil, suggesting great potential for the transmission of several arboviruses due to the difficulty in controlling these mosquitoes.