Northwestern Madagascar Research Articles

Three new species of plexippine jumping spiders (Salticidae, Salticinae, Plexippini) from dry forest in Boeny region, north-western Madagascar

Despite being the most diverse family of spiders, Salticidae (jumping spiders) are poorly studied in Madagascar with only 47 of the total 105 species recorded in the last 100 years. Here, we describe three new species of Plexippini Simon, 1901 from dry forests in North-western Madagascar as part of an ongoing biomonitoring programme. This paper increases the number of species in the genus Evarcha Simon, 1902 from 93 to 95 and Thyene Simon, 1885 from 55 to 56. Additionally, we publish specimen records of Plexippus petersi (Karsch, 1878) from Madagascar for the first time. All new species are diagnosed and illustrated through photographs and drawings.

Impatiens alboarenicola, a new species of Balsaminaceae from north-western Madagascar

A new species of Impatiens, I. alboarenicola (Balsaminaceae), is described and illustrated from Ankarafantsika National Park, north-western Madagascar. This species is similar to I. barthlottii and I. tsingycola in leaf and flower shape, but clearly distinguished from the former by its shorter stature, absence of a tuber at the stem base, solitary (rarely 2) flowers in the axils of leaves, and smaller flowers, and from the latter by its smaller leaf blades with fewer pairs of teeth on the dentate leaf margin, solitary (rarely 2) flowers in the axils of leaves, and saccate spur-like projection located at ca. 5 mm below the apex of the lower petal lobe of the lateral united petals (vs. at the apex of the lower petal lobe).

Simulation training on respectful emergency obstetric and neonatal care in north-western Madagascar: a mixed-methods evaluation of an innovative training program

BackgroundThe rates of maternal and neonatal deaths in Madagascar are among the highest in the world. In response to a request for additional training from obstetrical care providers at the Ambanja district hospital in north-eastern Madagascar, a partnership of institutions in Switzerland and Madagascar conducted innovative training on respectful emergency obstetric and newborn care using e-learning and simulation methodologies. The training focused on six topics: pre-eclampsia, physiological childbirth, obstetric maneuvers, postpartum hemorrhage, maternal sepsis, and newborn resuscitation. Cross-cutting themes were interprofessional communication and respectful patient care. Ten experienced trainers participated in an e-training-of-trainers course conducted by the Swiss partners. The newly-trained trainers and Swiss partners then jointly conducted the hybrid remote/in-person training for 11 obstetrical care providers in Ambanja.MethodsA mixed methods evaluation was conducted of the impact of the training on participants’ knowledge and practices. Trainees’ knowledge was tested before, immediately after, and 6 months after the training. Focus group discussions were conducted to elicit participants’ opinions about the training, including the content and pedagogical methods.ResultsTrainees’ knowledge of the six topics was higher at 6 months (with an average of 71% correct answers) compared to before the training (62%), although it was even higher (83%) immediately after the training. During the focus group discussions, participants highlighted their positive impressions of the training, including its impact on their sense of professional effectiveness. They reported that their interprofessional relationships and focus on respectful care had improved. Simulation, which was a new methodology for the participants native to Madagascar, was appreciated for its engaging and active format, and they enjoyed the hybrid delivery of the training. Participants (including the trainers) expressed a desire for follow-up engagement, including additional training, and improved access to more equipment.ConclusionThe evaluation showed improvements in trainees’ knowledge and capacity to provide respectful emergency care to pregnant women and newborns across all training topics. The hybrid simulation-based training method elicited strong enthusiasm. Significant opportunity exists to expand the use of hybrid onsite/remote simulation-based training to improve obstetrical care and health outcomes for women and newborns in Madagascar and elsewhere.

Topographical gradient of the structure and diversity of a woody plant community in a seasonally dry tropical forest in northwestern Madagascar

AbstractFew studies have evaluated the structure and dynamics of forests in Madagascar with high levels of endemism. Ankarafantsika National Park holds the largest of the remaining primary dry forests in northwestern Madagascar, where most of the forests have been lost or degraded by fire and other human activities. In this primary forest, we established a 15‐ha forest dynamics monitoring plot and mapped and identified all woody stems with a diameter at breast height (DBH) ≥5 cm. The forest stand was characterized by small‐sized individuals (75% of stems with DBH <10 cm, with 99% of trees with height <15 m), encompassing 35,758 tree and 513 liana individuals belonging to 160 species in 53 families (including 20 species of lianas accounting for 1.4% of the stems). Most species‐rich families were Rubiaceae, Fabaceae, Lamiaceae, and Malvaceae, which together encompassed 43 tree species and 23% of all tree individuals. The plot was located on a hill consisting of white sand at elevations from 150 to 200 m, with a gentle slope down from southwest to northeast. Over this elevation gradient, stem density and species diversity increased with elevation, while tree height and diameter decreased. The most abundant two species, Drypetes perrieri (Putranjivaceae) and Noronhia alleizettei (Oleaceae) are evergreen, suggesting the importance of a nutrient conservation strategy. These results provide the foundational knowledge necessary for the conservation and restoration of natural semi‐deciduous dry forests that used to cover large areas in northwestern Madagascar until recently.

Where the small things are: Modelling edge effects on mouse lemur population density and distribution in northwestern Madagascar.

Edge effects result from the penetration to varying depths and intensities, of abiotic and biotic conditions from the surrounding non-forest matrix into the forest interior. Although 70% of the world's forests are within 1 km of a forest edge, making edge effects a dominant feature of most forest habitats, there are few empirical data on inter-site differences in edge responses in primates. We used spatially explicit capture-recapture (SECR) models to determine spatial patterns of density for two species of mouse lemurs (Microcebus murinus and Microcebus ravelobensis) in two forest landscapes in northwestern Madagascar. The goal of our study was to determine if mouse lemurs displayed spatially variable responses to edge effects. We trapped animals using Sherman live traps in the Mariarano Classified Forest (MCF) and in the Ambanjabe Forest Fragment Site (AFFS) site within Ankarafantsika National Park. We trapped 126 M. murinus and 79 M. ravelobensis at MCF and 78 M. murinus and 308 M. ravelobensis at AFFS. For M. murinus, our top model predicted a positive edge response, where density increased towards edge habitats. In M. ravelobensis, our top model predicted a negative edge response, where density was lower near the forest edges and increased towards the forest interior. At regional and landscape-specific scales, SECR models estimated different density patterns between M. murinus and M. ravelobensis as a result of variation in edge distance. The spatial variability of our results using SECR models indicate the importance of studying the population ecology of primates at varying scales that are appropriate to the processes of interest. Our results lend further support to the theory that some lemurs exhibit a form of ecological flexibility in their responses to forest loss, forest fragmentation, and associated edge effects.

Zonal control on Holocene precipitation in northwestern Madagascar based on a stalagmite from Anjohibe

The Malagasy Summer Monsoon is an important part of the larger Indian Ocean and tropical monsoon region. As the effects of global warming play out, changes to precipitation in Madagascar will have important ramifications for the Malagasy people. To help understand how precipitation responds to climate changes we present a long-term Holocene speleothem record from Anjohibe, part of the Andranoboka cave system in northwestern Madagascar. To date, it is the most complete Holocene record from this region and sheds light on the nature of millennial and centennial precipitation changes in this region. We find that over the Holocene, precipitation in northwestern Madagascar is actually in phase with the Northern Hemisphere Asian monsoon on multi-millennial scales, but that during some shorter centennial-scale events such as the 8.2 ka event, Anjohibe exhibits an antiphase precipitation signal to the Northern Hemisphere. The ultimate driver of precipitation changes across the Holocene does not appear to be the meridional migration of the monsoon. Instead, zonal sea surface temperature gradients in the Indian Ocean seem to play a primary role in precipitation changes in northwestern Madagascar.

Non fire-adapted dry forest of Northwestern Madagascar: Escalating and devastating trends revealed by Landsat timeseries and GEDI lidar data.

Ankarafantsika National Park (ANP), the last significant remnant of Northwestern Madagascar's tropical dry forests, is facing rapid degradation due to increased incidences of fire. This poses severe threats to biodiversity, local livelihoods, and vital ecosystem services. Our study, conducted on 3,052-ha of ANP's pristine forests, employed advanced remote-sensing techniques to assess fire impacts during the past 37 years. Our aims were to understand historical fire patterns and evaluate forest recovery and susceptibility to repeated fires following initial burns. Using data from multiple Landsat satellite sensors, we constructed a time series of fire events since 1985, which revealed no fire activity before 2014. The Global Ecosystem Dynamics Investigation (GEDI) lidar sensor data were used to observe forest structure in both post-fire areas and undisturbed zones for comparison. We recorded six fire incidents from 2014-2021, during which the fire-affected area exponentially grew. A significant fire incident in October 2021 impacted 1,052 hectares, 59% of which had experienced at least one fire in two-to-four years prior, with 60% experiencing two preceding incidents: one in 2017 and another in 2019. The initial fire drastically reduced plant cover and tree height, with subsequent fires causing minor additional loss. Post-fire recovery was negligible within the initial four years, even in patches without recurrent fires. The likelihood for an initial burn to trigger subsequent fires within a few years was high, leading to larger, more severe fires. We conclude that ANP's dry forests exhibit high vulnerability and low resilience to anthropogenic fires. Prompt preventive measures are essential to halt further fire spread and conserve the park's unique and invaluable biodiversity.

A speleothem record of hydroclimate variability in northwestern Madagascar during the mid-late Holocene

We present a continuous high-resolution precisely dated multiproxy record of hydroclimate variability at Anjohibe cave in northwestern Madagascar using speleothem AB13. The record spans from ~4484 y BP to ~2863 y BP. Stalagmite δ18O, δ13C and Sr/Ca ratios show very similar changes in hydroclimate. The mechanism controlling Sr/Ca changes, however, from prior calcite precipitation to degree of dolomite dissolution at about 4 ky BP. Our record is also in good agreement with previously published speleothem records from the same area. This agreement and multiproxy consensus indicate that AB13 provides a robust record of hydroclimate variability, including a continuous record of hydroclimate variability across the 4.2 ka event. This 4.2 ka event in Madagascar is marked by two distinct periods of drying between ~3900 y BP to 4300 y BP. A dry 4.2 ka event at this Southern Hemisphere site helps limit possible mechanisms for the event, indicating that a meridional shift to the south in the ITCZ is not responsible for the 4.2 ka event. In addition, the 4.2 ka event does not stand out as a unique dry period in our record. The longest and driest period of the record lasted ~300 years with peak dryness at ~3000 y BP. Our record differs significantly from a speleothem record from Rodrigues Island, located ~1800 km to the east of our study area in Madagascar suggesting different climatological controls on northwest Madagascar and more oceanic sites to the east.

Integrative revision of the Blommersia wittei complex, with description of a new species of frog from western and north-western Madagascar.

Frogs of the Blommersia wittei complex are widespread in western and northern Madagascar, and are one of two clades of the family Mantellidae that have colonized the Comoran island of Mayotte. Based on a comprehensive set of DNA sequences of the mitochondrial 16S rRNA gene and the nuclear-encoded RAG1 and SACS genes, integrated with morphological and bioacoustic data, we here analyze the genetic differentiation of populations of this complex across Madagascar. We confirm that a candidate species named B. sp. Ca5 in previous studies represents a genetically well-defined evolutionary lineage distributed over much of western Madagascar, which we describe herein as Blommeria bara sp. nov. based on its molecular and bioacoustic differentiation. Blommersia wittei occurs across northern Madagascar but its type locality Ambanja, at the lower Sambirano river, is very close to the range of another, newly discovered microendemic lineage that was only found at two sites along the upper Sambirano river (here named as candidate species B. sp. Ca12). The B. wittei complex thus provides an example of a clade of closely related Malagasy frogs that contains species widespread over hundreds of kilometers, as well as extreme microendemics. For a full resolution of this species complex, more data need to be collected on the geographical contact among these two lineages, on the morphology and bioacoustics of B. sp. Ca12, and on the north-eastern populations of B. wittei at Sambava, which are weakly differentiated in mitochondrial genes but differ in bioacoustics and possibly in the extent of foot webbing.

Effects of Forest Fragmentation on Connectivity and Genetic Diversity in an Endemic and an Invasive Rodent in Northwestern Madagascar.

Habitat loss and fragmentation are of concern to conservation biologists worldwide. However, not all organisms are affected equally by these processes; thus, it is important to study the effects of living in fragmented habitats on species that differ in lifestyle and habitat requirements. In this study, we examined the dispersal and connectivity patterns of rodents, one endemic (Eliurus myoxinus) and one invasive (Rattus rattus), in two landscapes containing forest fragments and adjacent continuous forest patches in northwestern Madagascar. We generated genetic (RADseq) data for 66 E. myoxinus and 81 R. rattus individuals to evaluate differences in genetic diversity as well as inbreeding and connectivity in two landscapes. We found higher levels of inbreeding and lower levels of genetic diversity in E. myoxinus compared with R. rattus. We observed related dyads both within and between habitat patches and positive spatial autocorrelation at lower distance classes for both species, with a stronger pattern of spatial autocorrelation in R. rattus. Across each site, we identified contrasting migration rates for each species, but these did not correspond to habitat-matrix dichotomies. The relatively low genetic diversity in the endemic E. myoxinus suggests ecological constraints that require further investigation.

First postcranial remains of the Late Cretaceous gondwanatherian mammal Vintana sertichi

Postcranial remains of gondwanatherian mammals were previously known by only a single specimen, an essentially complete skull and postcranial skeleton constituting the holotype and only known specimen of Adalatherium hui (UA 9001), from the uppermost Cretaceous (Maastrichtian) Anembalemba Member of the Maevarano Formation, Mahajanga Basin, northwestern Madagascar. Here we report the discovery of a caudal vertebra (DMNH EPV.141354) that we provisionally refer to a much larger gondwanatherian, Vintana sertichi, also from the Maevarano Formation. V. sertichi, the largest known mammal from the Mesozoic of Gondwana, was previously represented only by a cranium from the Lac Kinkony Member, which represents a nearshore, peritidal paleoenvironment, but the caudal vertebra was recovered from the underlying Anembalemba Member, which represents an earlier, more fully terrestrial fluvial/floodplain paleoenvironment. The presence of V. sertichi in the latter rock unit therefore expands the age (making it more fully contemporaneous with A. hui) and the known paleoenvironmental range for the species. Comparing various metrics of vertebral body proportions suggests that (1) gondwanatherians are unique among Mesozoic mammals in possessing mid-caudal vertebral centra that are anteroposteriorly short; and (2) the tail of V. sertichi was relatively wider and shorter than that of A. hui.

Host-related and environmental factors influence long-term ectoparasite infestation dynamics of mouse lemurs in northwestern Madagascar.

Parasite infestations depend on multiple host-related and environmental factors. In the case of ectoparasites, which are exposed to the environment beyond the host, an impact of climate, expressed by seasonal or yearly variations, can be expected. However, long-term dynamics of ectoparasite infestations are rarely studied in nonhuman primates. We investigated the yearly variations in ectoparasite infestations of two small primates, the gray (Microcebus murinus) and the golden-brown (Microcebus ravelobensis) mouse lemur. For a more comprehensive evaluation, we also analyzed the potential effects of yearly and monthly climatic variation (temperature, rainfall) in addition to habitat, host sex, age, species, and body mass, on ectoparasite infestation. Individuals of both host species were sampled in two study sites within the Ankarafantsika National Park in northwestern Madagascar during several months (March-November) and across 4 years (2010, 2011, 2015, 2016). Our results show significant monthly and yearly variations in the infestation rates of three native ectoparasite taxa (Haemaphysalis spp. ticks, Schoutedenichia microcebi chigger mites, Lemurpediculus spp. sucking lice) and in ectoparasite species richness in both mouse lemur species. In addition, significant impacts of several host-related (species, sex, body mass) and environmental factors (habitat, temperature, rainfall) were found, but with differences in relevance for the different parasite taxa and partly deviating in their direction. Although some differences could be attributed to either permanent or temporary presence of the parasites on the host or to ecological differences between the host species, the lack of specific knowledge regarding the life cycle and microhabitat requirements of each parasite taxon precludes a complete understanding of the factors that determine their infestation dynamics. This study demonstrates the presence of yearly and monthly dynamics in lemur-parasite interactions in tropical, seasonal, dry deciduous forests in Madagascar, which call out for broad ecological long-term studies focusing both on primate hosts and their parasites.

A large, freshwater chanid fish (Ostariophysi: Gonorynchiformes) from the Upper Cretaceous of Madagascar

ABSTRACT Isolated fossil bones from freshwater Upper Cretaceous (Maastrichtian) deposits in the Mahajanga Basin of northwestern Madagascar are identified as belonging to a gonorynchiform fish. Multiple elements representing the same bone, including opercles, hyomandibulae, frontals, and basioccipitals, indicate that only a single gonorynchiform species is present. The most diagnostic element is here named as a new genus and species, †Vango fahiny; the other elements likely belong to the same taxon. The Madagascan gonorynchiform material shares features with members of the subfamily Chaninae and is assigned to that group. It is similar to the extant milkfish Chanos chanos but can be easily distinguished from that species by numerous features, such as the basioccipital and maxilla being relatively shorter than those of C. chanos, and the opercle being overall rounder and having a shorter auricular process. The presence of a chanid in Madagascar in the Maastrichtian most likely represents an invasion of a marine lineage into fresh waters. The previously known Cretaceous fossils of gonorynchiforms are spread throughout the Tethys Sea in mid-latitude to northern regions from the east (e.g., Lebanon, Europe) through to the southwest (e.g., Mexico, Brazil). †Vango faniny gen. et sp. nov. represents the first Mesozoic/Paleogene record of gonorynchiforms in East Gondwana, comprising primarily Antarctica, Australia, Madagascar, and the Indian subcontinent.

Non-marine Molluscs Of The Northern Narinda Karst, North-western Madagascar

The non-marine mollusc fauna of the northern part of t1he Narinda karst of north-western Madagascar, mostly from the Anjajavy Peninsula and Analalava District is enumerated based on collections made in the past 20 years. 102 species are recorded (73 terrestrial, 12 freshwater and 17 littoral). Twenty four are described as new species: Omphalotropis lavanensis n. sp., Boucardicus crassus n. sp., Boucardicus malama n. sp., Boucardicus minoratus n. sp., Cyclotopsis pectinata n. sp., Tropidophora narindana n. sp., Tropidophora tenona n. sp., Tropidophora jugia n. sp., Tropidophora neoliratoides n. sp., Tropidophora rovidrovitra n. sp., Gulella foucaultia n. sp., Gulella martiniana n. sp., Gulella anjajavyensis n. sp., Gulella volontany n. sp., Gulella antonibe n. sp., Parvedentulina lavana n. sp., Microcystis zorony n. sp., Microcystis embertoni n. sp., Sitala dickensi n. sp., Ctenophila tangolika n. sp., Kalidos unistriata n. sp., Kalidos quadrangulata n. sp., Kalidos narindana n. sp., and Kalidos mahafatifaty n. sp. A further six are new records for Madagascar. We propose two changes of genera and one new synonym. Madagascar’s dry forest continues to decline in area and much of the forest in the region is fragmentary. Three species were only recorded from old shells and may be locally extinct.

Filarial infections in lemurs:Evidence for a wide geographical distribution and low host specificity among lemur species.

The relevance of emerging infectious diseases continues to grow worldwide as human activities increasingly extend into formerly remote natural areas. This is particularly noticeable on the island of Madagascar. As closest relatives to humans on the island, lemurs are of particular relevance as a potential origin of zoonotic pathogen spillover. Knowledge of pathogens circulating in lemur populations is, however, very poor. Particularly little is known about lemur hemoparasites. To infer host range, ecological and geographic spread of the recently described hemoparasitic nematode Lemurfilaria lemuris in northwestern Madagascar, a total of 942 individuals of two mouse lemur species (Microcebus murinus [n = 207] and Microcebus ravelobensis [n = 433]) and two rodent species (the endemic Eliurus myoxinus [n = 118] and the invasive Rattus rattus [n = 184]) were captured in two fragmented forest landscapes (Ankarafantsika National Park and Mariarano Classified Forest) in northwestern Madagascar for blood sample examination. No protozoan hemoparasites were detected by microscopic blood smear screening. Microfilaria were present in 1.0% (2/207) of M. murinus and 2.1% (9/433) of M. ravelobensis blood samples but not in rodent samples. Internal transcribed spacer 1 (ITS-1) sequences were identical to an unnamed Onchocercidae species previously described to infect a larger lemur species, Propithecus verreauxi, about 650 km further south. In contrast to expectations, L. lemuris was not detected. The finding of a pathogen in a distantly related host species, at a considerable geographic distance from the location of its original detection, instead of a microfilaria species previously described for one of the studied host species in the same region, illustrates our low level of knowledge of lemur hemoparasites, their host ranges, distribution, modes of transmission, and their zoonotic potential. Our findings shall stimulate new research that will be of relevance for both conservation medicine and human epidemiology.

Measuring the Impact of Forest Edges on the Highly Arboreal Sahamalaza Sportive Lemur, Lepilemur Sahamalaza, in North-Western Madagascar

The progressive fragmentation of forest habitat is causing an increase in edge areas that may differ structurally and in quality from forest interiors. We investigated the impact of edge effects on habitat structure, behaviour, and ecology of the small, nocturnal, and highly arboreal Sahamalaza sportive lemur, Lepilemur sahamalaza. To understand edge effects, we established edge-to-interior gradients using temperature, humidity, and light intensity measurements along transects. From 773 h of behavioural observations on 14 individual sportive lemurs between 2015 and 2016, we compared home range sizes, activity budgets, and habitat use of animals inhabiting the edge area and those in the core forest. We found that microclimatic edge effects penetrated the forest up to 165 m, but that there was no significant edge effect on vegetation; forest vegetation was structurally variable throughout. Individual sportive lemurs living in the edge area used more trees with a diameter at breast height of less than 5 cm but showed no other behavioural differences to individuals inhabiting the core forest. The study shows that this species may not be impacted by edge effects, at least in situations in which vegetation structure is not affected, despite microclimatic differences.

Retraction: Teixeira et al. RADseq Data Suggest Occasional Hybridization between Microcebus murinus and M. ravelobensis in Northwestern Madagascar. Genes 2022, 13, 913.

The published article [...].

Multimale breeding aggregations by “many-friends” snakes: courtship behaviours by Malagasy Pseudoxyrhophiine snakes, Dromicodryas bernieri and D. quadrilineatus, and their sexual size dimorphism

When several male snakes dispute over one female in the breeding season, two major male-male rivalries are known to occur: male-male combat and multimale breeding aggregation. The roles of male body size and the degree of sexual size dimorphism are different between these rivalries. We report field observations of mating behaviour including a multimale breeding aggregation of pseudoxyrhophiins, Dromicodryas bernieri and D. quadrilineatus, in northwestern Madagascar, which have a local name, “Maro longo”, meaning “many friends”. To examine the relationships between sexual size dimorphism and mating strategies of males, we also analysed the body size of the two species of Dromicodryas and two other pseudoxyrhophiins, Leioheterodon madagascariensis and L. modestus, which are known to exhibit the male-male combat. Our data obtained during a long-term field study showed that D. bernieri and D. quadrilineatus have female-biased sexual size dimorphism, whereas L. madagascariensis and L. modestus have male-biased sexual size dimorphism. This result conforms to the general tendency of the relationship between body size and male-male rivalry in snakes.

Using satellite images to monitor burned areas in Madagascar

Mapping the extent of fire-affected areas is very important for integrated fire management, especially for stakeholder communication and mobilization, rehabilitation of burned areas, and decision making. A prerequisite to planning fire response strategies requires accurate quantitative data on when and where fires occur. This article reports on a study carried out in 2021 over an area of 1,575 ha in and around Ankarafantsika National Park in northwestern Madagascar using satellite images, drone images and ground-truth data to assess the accuracy and usefulness of mapping in quantifying burned areas. During that year, 13,073 ha were burned in the park (about 10% of its total area). Based on the successful use of satellite mapping data, the REAFMRC geoportal is being extended to cover all East African countries.

Agricultural fuelbreaks in sustainable fire-resilient landscapes in Madagascar

The first 65 km of agricultural fuelbreaks in the country were established in Boeny Region, northwestern Madagascar in 2021 and 2022. Mostly in grassy savanna, these fuelbreaks limit the spread of fires, and have also create an additional 615 ha of farmland for crop production. This should reduce the cleating in the national park and so reduce future fire ignitions. Due to the benefits seen by local smallholders and decision makers, their use has already spread to more locations. The keys to success are territorial land-use plans that make it possible to create fire-resistant mosaic landscapes that combine forest and agricultural land. The goal is to find sustainable solutions to the problem of fire, while in parallel, creating agricultural, economic and social opportunities.