East Madagascar Research Articles

Two new species of Diastatotropis Lacordaire from protected areas in central and east Madagascar (Coleoptera: Anthribidae).

Two new species, Diastatotropis lusti Trýzna, Blažej & Rakotonirina sp. nov. and Diastatotropis petulae Trýzna, Blažej & Rakotonirina sp. nov. (Anthribidae: Anthribinae: incertae sedis), from Madagascar are described, including colour habitus photographs, drawings of male and female genitalia, ecological notes and photographs of the habitat.

A new miniaturized species of leaf chameleon, genus Brookesia, from a littoral forest fragment in eastern Madagascar.

The number of species of miniaturized chameleons of the genus Brookesia, subgenus Evoluticauda, known to science has witnessed a dramatic increase over the past 15 years, due to the discovery of multiple microendemic species of very strong genetic divergence. So far, no described Evoluticauda species are known from the littoral forest of Madagascar's east coast, one of the most threatened habitat types of the island. Here, we report on the discovery of a new species of Evoluticauda occurring in the littoral forest at Ankanin'ny Nofy, a touristic site at about sea level and close to Vohibola forest where probably the same species occurs. The new species, Brookesia nofy sp. nov., is sister to B. ramanantsoai which occurs in mid-altitude and highland forests (800-1300 m a.s.l.) at a similar latitude of eastern Madagascar, but differs from this species by an enormous genetic divergence in both mitochondrial and nuclear genes (8.1-9.4% uncorrected pairwise distance in the 16S rRNA gene, 1.8-2.5% in c-mos), a relatively shorter tail, a different arrangement of cephalic ridges, and probably smaller body size and relatively larger head. The discovery of B. nofy sp. nov. emphasizes the importance of conserving Madagascar's last remaining fragments of littoral forest.

Intra-species variability in migratory movement of hawksbill turtles in the southwest Indian Ocean

Implementing effective conservation measures to manage migratory populations is challenging, especially in a relatively inaccessible dynamic environment such as the ocean. With limited financial and human resources, efforts must be intelligently prioritized to achieve conservation success and reduce uncertainties of conservation efforts. The southwest Indian Ocean (SWIO) hosts some of the world’s most important breeding grounds for the Critically Endangered hawksbill turtle Eretmochelys imbricata. However, knowledge gaps remain about the movement patterns of this species. Between 2007 and 2022, we deployed 17 satellite tags onto hawksbill turtles from scattered locations in the SWIO: 16 nesting females—Granitic Islands, Seychelles (n = 9); north Madagascar (n = 5); Moheli, Comoros (n = 1); Juan de Nova, Terres australes et antarctiques françaises (n = 1)—and 1 female bycaught in fisheries (east Madagascar). We found strong variability in migratory movements amongst individuals, particularly in terms of distance and movement persistence. Detailed analysis of movement persistence reveals that these individuals behave differently in neritic and oceanic habitats, with a lower movement persistence in neritic habitats. We identified a total of 12 foraging areas scattered throughout the SWIO, both in coastal and open-sea neritic habitats. These results reinforce the need to consider the importance of neritic habitats, for both migration and foraging, in conservation policies. The quantification of the degree of migratory variability is particularly important to developing conservation plans and strategies at both the national and international level, including the delineation of regional management units (RMUs) in the Indian Ocean.

Chlorophyll bloom triggered by tropical storm chedza at the southern tip of madagascar island

Abstract A phytoplankton bloom during the passage of Tropical Storm (TS) Chedza was observed at the southern tip of Madagascar on January 28, 2015. The mechanisms of the chlorophyll bloom were researched with satellite remote sensing data, reanalysis data and Argo buoy data. The results show that there was horizontal transport of chlorophyll-a (Chl-a) with the western coastal current of Madagascar and the South East Madagascar Current (SEMC). At the southern tip of Madagascar, there was a tilted anticyclonic eddy moving westward, which promoted the flow of nitrate at depths from 60 m to 100 m northward into Box A for a month. Simultaneously, the SEMC formed another anticyclonic eddy entering Box C. Following the passage of TS Chedza, cyclone vorticity in Box A increased continuously, and the upwelling became stronger with Ekman pumping. At the same time, the barrier layer weakened, the mixed layer deepened, and the thermocline decreased, which can uplift the nitrate to the upper ocean. After the passage of TS Chedza, sufficient photosynthetically active radiation (PAR) facilitated the Chl-a bloom in Box A. This study contributes to the assessment of the ecological impact of ocean eddies at the southern tip of Madagascar.

A new species of Xylodes Waterhouse from Madagascar, with a key to the genera of the tribe Ptinini from Madagascar, Mascarenes and adjacent regions, and a key to species of Xylodes, subgenus Diegous (Coleoptera: Ptinidae).

A new species, Xylodes (Diegous) korinae Zahradnk & Trzna sp. nov. (Bostrichoidea: Ptinidae, Ptininae, Ptinini), from east Madagascar is described, illustrated and compared with other species from the subgenus Diegous Pic, 1896. Male and female genitalia are studied and illustrated. Keys to morphologically similar genera from Madagascar and adjacent areas, to both subgenera of the genus Xylodes Waterhouse, 1876, and to all species of the subgenus Diegous are presented. Ecological notes, including photographs of habitats of the new species are also provided.

Life History Traits and Longevity of the Invasive Asian Common Toad Duttaphrynus melanostictus (Schneider, 1799) in Madagascar

We analyzed the body length, age structure, and age at sexual maturity of the invasive Asian common toad Duttaphrynus melanostictus from different sites in Toamasina, east Madagascar. We used skeletochronology as a proxy for age estimation, while gonads were histologically analyzed to determine the age of sexual maturity. The analysis of pooled age data from three sites investigated in 2016 showed that both sexes were larger, although not older, than those of native populations. For the individuals from Madagascar, the males were significantly smaller and younger (mean ± SD, SVL: 71.4 ± 1.6 mm; age: 1.8 ± 0.7 years) than the females (SVL: 78.42 ± 1.9 mm; age: 2.7 ± 1.3 years), when the data were pooled, but when the data were analyzed separately for each of the three sites, similar results were obtained only for one site. The oldest recorded male and female were 3 and 6 years old, respectively. Gonadal histology showed that the males and females reach sexual maturity after the first and second years of age, respectively. Further studies are needed to understand if the larger size and faster growth rates observed in the invasive population of D. melanostictus in Madagascar are a consequence of more favorable environmental conditions with respect to the native range (e.g., the availability of larger trophic niches, a lack of competitors, and lower predatory pressure), and we suggest to extend the monitoring of these life history traits to understand how they might influence the invasion.

Ecological niche model transferability of the white star apple (Chrysophyllum albidum G. Don) in the context of climate and global changes

Chrysophyllum albidum is a forest food tree species of the Sapotaceae family bearing large berries of nutrition, sanitary, and commercial value in many African countries. Because of its socioeconomic importance, C. albidum is threatened at least by human pressure. However, we do not know to what extent climate change can impact its distribution or whether it is possible to introduce the species in other tropical regions. To resolve our concerns, we decided to model the spatial distribution of the species. We then used the SDM package for data modeling in R to compare the predictive performances of algorithms among the most commonly used: three machine learning algorithms (MaxEnt, boosted regression trees, and random forests) and three regression algorithms (generalized linear model, generalized additive models, and multivariate adaptive regression spline). We performed model transfers in tropical Asia and Latin America. At the scale of Africa, predictions with respect to Maxent under Africlim (scenarios RCP 4.5 and RCP 8.5, horizon 2055) and MIROCES2L (scenarios SSP245 and SSP585, horizon 2060) showed that the suitable areas of C. albidum, within threshold values of the most contributing variables to the models, will extend mostly in West, East, Central, and Southern Africa as well as in East Madagascar. As opposed to Maxent, in Africa, the predictions for the future of BRT and RF were unrealistic with respect to the known ecology of C. albidum. All the algorithms except Maxent (for tropical Asia only), were consistent in predicting a successful introduction of C. albidum in Latin America and tropical Asia, both at present and in the future. We therefore recommend the introduction and cultivation of Chrysophyllum albidum in the predicted suitable areas of Latin America and tropical Asia, along with vegetation inventories in order to discover likely, sister or vicarious species of Chrysophyllum albidum that can be new to Science. Africlim is more successful than MIROCES2L in predicting realistic suitable areas of Chrysophyllum albidum in Africa. We therefore recommend to the authors of Africlim an update of Africlim models to comply with the sixth Assessment Report (AR6) of IPCC.

The taxonomic identity of the monocle bream Scolopsis vosmeri species complex (Perciformes: Nemipteridae), with comments on molecular phylogenetic relationships within the genus Scolopsis.

The monocle bream Scolopsis vosmeri species complex is revised. Three species in the complex are recognized: Scolopsis vosmeri (Bloch, 1792), widespread in the Indo-West Pacific, from the northern Indian Ocean (Pakistan, western India, Sri Lanka, Bay of Bengal, and the Andaman Sea, but not recorded from the Red Sea or Arabian Gulf, east African coast or Madagascar) to western Indonesia and Borneo; S. japonica (Bloch, 1793), restricted to the western Pacific Ocean from western Indonesia and north-western Australia east to the Philippines and north to southern Japan; and S. curite Cuvier, 1815, widespread from the western to the eastern Indian Ocean, including the Red Sea and Arabian Gulf. All three species are similar morphologically, and have been confused taxonomically, but phylogenetic analysis of the COI barcoding region shows they are evolutionarily divergent. The three species are redescribed in detail and characters found to distinguish them. Scolopsis vosmeri is easily distinguished from S. japonica and S. curite in having a white band along the side of the body; having a black spot on most body scales (versus greenish yellow spot in S. japonica and S. curite); in lacking a distinct black spot (sometimes a small and faint spot present) on the upper pectoral-fin base (versus small black wedge-shaped spot present in S. japonica and S. curite); caudal peduncle whitish in live individuals (versus caudal peduncle usually yellowish in S. japonica and S. curite); and pelvic and anal fins crimson to orange-red (versus yellow in S. japonica and S. curite). Scolopsis japonica and S. curite are indistinguishable by color pattern but differ in the degree of spination on the preopercular margin. Neotypes are designated for Scolopsis japonica and S. curite. Nomenclatural problems, including validity of the genus Scolopsis, are discussed. We regard Scolopsis curite Cuvier, 1815 as a valid binomial name and thus the type species of Scolopsis Cuvier, 1814 by subsequent monotypy.

Stingless bees (Hymenoptera: Apidae) in Holocene copal and Defaunation resin from Eastern Africa indicate Recent biodiversity change

Although specimens in fossil to Recent resins are remarkable for their fidelity of preservation, amber is well known and studied, unlike the younger resins as Pleistocene copal (2.58–0.0117 Ma) and Holocene copal (0.0117 Ma–1760 AD), or Defaunation resin, which is resin produced after 1760 AD. However, the scientific relevance of these younger resins preserving arthropods that lived in pre-Anthropocene time is often underestimated. Here, we present specimens of workers of stingless bees included in copal and Defaunation resin, from the coastal vichaka forests in Tanzania, and from northwest Madagascar, ranging in age from almost 3000 BP years to only 80 ± 30 BP years and from 2015, respectively. Three known species Hypotrigona gribodoi, Liotrigona bouyssoui, and Liotrigona nilssoni and two new species Axestotrigona kitingae sp. nov. and Hypotrigona kleineri sp. nov. have been discovered from 36 studied specimens. We also noted that the holotype of Trigona richardsi is a junior subjective synonym of Axestotrigona ferruginea ferruginea. The coastal forests in the East Africa region and in East Madagascar are now highly fragmented so that we can expect that the new species are already extinct. Here we demonstrate that the study of inclusions in copal and Defaunation resin can document losses of local biodiversity resulting, for example, from deforestation and they also bring proof of this potential anthropic defaunation.

Where and How the East Madagascar Current Retroflection Originates?

AbstractThe East Madagascar Current (EMC) is one of the western boundary currents of the South Indian Ocean. As such, it plays an important role in the climate system by transporting water and heat toward the pole and recirculating to the large‐scale Indian Ocean through retroflection modes of its southern extension. Five cruise data sets and remote sensing data from different sensors are used to identify three states of the southern extension of the EMC: early retroflection, canonical retroflection, and no retroflection. Retroflections occur 47% of the time. EMC strength regulates the retroflection state, although impinged mesoscale eddies also contribute to retroflection formation. Early retroflection is linked with EMC volume transport. Anticyclonic eddies drifting from the central Indian Ocean to the coast favor early retroflection formation, anticyclonic eddies near the southern tip of Madagascar promote the generation of canonical retroflection, and no retroflection appears to be associated with a lower eddy kinetic energy (EKE). Knowledge of the EMC retroflection state could help predict (a) coastal upwelling south of Madagascar, (b) the southeastern Madagascar phytoplankton bloom, and (c) the formation of the South Indian Ocean Counter Current (SICC).

Global Dialysis Perspective: Mauritius.

The Republic of Mauritius consists of several groups of small islands, spread over a large area of the south-west Indian Ocean. The largest two islands are Mauritius, 800 km east of Madagascar, and Rodrigues, a further 600 km east of Mauritius (Figure 1). Mauritius is well served by shipping routes and numerous daily international flights. Rodrigues is linked to Mauritius by several daily flights, and less frequently by cargo ships. It is geographically linked to the African continent, but most inhabitants are descended from immigrants from Asia. The main ethnicities are Indian, Creole, Chinese, and European. The population of Mauritius as of December 31,2019 was 1,265,475 people, and there is an ageing population structure compared with most African countries (1). Figure 1. The islands of Mauritius in the south-west Indian Ocean off the coast of East Africa, with details of the hemodialysis centers on the two larger islands. 1, Sir Seewoosagur Ramgoolam National Hospital; 2, Dr AG Jeetoo Hospital; 3, Dr Bruno Cheong Hospital; 4, Victoria Hospital; 5, Jawaharlal Nehru Hospital; 6, Queen Elizabeth Hospital; 7, Long Mountain Hospital; and 8, Souillac Hospital. Mauritius, an upper-middle–income country for many years, was classified as a high income country (2) for the first time in July 2020, just as the devastating coronavirus disease 2019 pandemic struck. In 2017, the Mauritius Gini coefficient was 36.8 (3) and the health expenditure was 6% of GDP (4). The Mauritius welfare system provides a network of community and area health centers, mediclinics, district and specialized hospitals, administered from five larger regional hospitals. Although all aspects of health care are free of charge, a sizeable proportion of the population prefer to pay for the services of general practitioners, specialists, and clinics in the private sector. The burden of noncommunicable disease is considerable. Mauritius has ranked in the top …

Sustained Decadal Warming Phase in the Southwestern Indian Ocean since the Mid-1990s

Regardless of the slowdown in global warming during the hiatus period, sea surface temperatures (SSTs) in the southwestern Indian Ocean (SWIO) have experienced sustained decadal warming for more than two decades since the mid-1990s. The SWIO SSTs warmed steadily during 1996–2016, causing a warming hot spot of 0.4 K decade−1 in a large region east of Madagascar. An upper-layer heat budget analysis indicated that heat advection by ocean currents was the greatest contributor to the warming of the SWIO SSTs. The existence of an anticyclonic geostrophic current along the western boundary of the SWIO tended to maintain such warming by transporting warmer water from the west into the SWIO region. In addition, net positive heat transport by ocean currents also occurred at the southern boundary of the SWIO as the climatological northward transport of cold water from the Southern Ocean weakened. This reduction in northward ocean currents at the surface was caused by local wind stress changes, leading to a southward Ekman current. Below the surface, an anticyclonic geostrophic current pattern existed around the warming center near the southeastern SWIO, which reduced the transport of cold waters from the Southern Ocean and warmed the SWIO. These processes near the two boundaries formed a self-sustaining positive feedback mechanism and favored the maintenance of sustained warming in the SWIO. More attention is needed to analyze the sustained long-lasting warming in the SWIO, as it is a unique phenomenon occurring under the background of the ongoing global warming.

Deep-water Photinae (Gastropoda: Nassariidae) from eastern Africa, with descriptions of five new species

Deep-water species from the western Indian Ocean off the East African coast and Madagascar, belonging to the subfamily Photinae, are discussed and compared with species from the West Pacific. Phos elegantissimus Hayashi & Habe, 1965, P. hirasei Sowerby, 1913 and P. laevis Kuroda & Habe in Habe, 1961 are recorded from Mozambique and/or from Madagascar, hereby extending their known range considerably into the western Indian Ocean. The East African specimens formerly assigned to Phos roseatus Hinds, 1844 are found to differ from this West Pacific species. In total, five species are described as new: Phos ganii sp. nov., P. geminus sp. nov., P. ladoboides sp. nov., P. pulchritudus sp. nov. and P. testaceus sp. nov.

Connectivity and population structure of albacore tuna across southeast Atlantic and southwest Indian Oceans inferred from multidisciplinary methodology

Albacore tuna (Thunnus alalunga) is an important target of tuna fisheries in the Atlantic and Indian Oceans. The commercial catch of albacore is the highest globally among all temperate tuna species, contributing around 6% in weight to global tuna catches over the last decade. The accurate assessment and management of this heavily exploited resource requires a robust understanding of the species’ biology and of the pattern of connectivity among oceanic regions, yet Indian Ocean albacore population dynamics remain poorly understood and its level of connectivity with the Atlantic Ocean population is uncertain. We analysed morphometrics and genetics of albacore (n = 1,874) in the southwest Indian (SWIO) and southeast Atlantic (SEAO) Oceans to investigate the connectivity and population structure. Furthermore, we examined the species’ dispersal potential by modelling particle drift through major oceanographic features. Males appear larger than females, except in South African waters, yet the length–weight relationship only showed significant male–female difference in one region (east of Madagascar and Reunion waters). The present study produced a genetic differentiation between the southeast Atlantic and southwest Indian Oceans, supporting their demographic independence. The particle drift models suggested dispersal potential of early life stages from SWIO to SEAO and adult or sub-adult migration from SEAO to SWIO.

959. BREXIA MADAGASCARIENSIS

SummaryBrexia madagascariensis (Lam.) Ker Gawl is native in East Madagascar. There are at least 25 known subpopulations growing mostly in humid forest (IUCN 2020), particularly in remnant patches of coastal forest. It was listed as ‘Least Concern’ on the IUCN Red Lists in 2007; however, continuing pressure on forests and potential taxonomic changes may require this to be reviewed. Madagascar has very high deforestation rates, primarily caused by logging and widespread shifting cultivation. Germination and cultivation for in‐situ and ex‐situ conservation are easily achievable and this small tree is ideal for education and display in botanic gardens. The leaves of juvenile plants are long and spiny, while the adult leaves tend to be more rounded and lack the spines.

Satellite observations of phytoplankton enrichments around seamounts in the South West Indian Ocean with a special focus on the Walters Shoal

Spatial anomalies associated with seamounts and islands have been detected in the South West Indian Ocean using a new surface chlorophyll-a based enrichment index (EI). Calculated from daily L3 4-km MODIS chl-a data from 2003 to 2018, the EI was used to quantify recurrent (seasonal) surface enrichment associated with these features. Most notable were the shallow Walters Shoal (18 m) and nearby deeper WS-2 seamount (480 m), both located on the southern Madagascar Ridge, which showed high EI values of 40% and 15% local enhancement. Tromelin Island, east of Madagascar, exhibited more moderate values of 15% local increase. Other shallower seamounts including La Pérouse (60 m) and MAD-Ridge (240 m) exhibited sporadic or no measurable surface maxima. Regions of strong mesoscale activity such as south of Madagascar where the South East Madagascar Current detaches from the continent also revealed high EI values. A marked seasonality of the EI was observed over the Walters Shoal, with higher values during the oligotrophic season than in the austral winter. The seasonal variability of the MLD in combination with the seamount bathymetry appears to induce the thermal and biological anomalies observed there, possibly favoured by the presence of a Taylor cap at the summit. Ship-collected in situ measurements showed the satellite observed enrichment to be associated with shallowing of the deep chlorophyll maximum, as well as a shift of phytoplankton groups towards diatoms and small flagellates. No net increase of integrated chl-a was measured but a potential doubling in primary productivity is expected. The EI developed in this study, designed to reveal sporadic, small localised chl-a maxima, is likely applicable to other areas in the ocean where there is local enrichments.

The MADRidge project: Bio-physical coupling around three shallow seamounts in the South West Indian Ocean

Compared with other ocean basins, little is known scientifically about the seamounts in the Indian Ocean. Nonetheless, fishers have plundered these fragile ecosystems for decades, and now mining is becoming a reality. We introduce a multidisciplinary project referred to as MADRidge that recently focused on three shallow seamounts in the South West Indian Ocean between 19°S and 34°S. The larger Walters Shoal (summit at 18 m) discovered in 1963 occupies the southern part of the Madagascar Ridge and has long received attention from the fishing industry, and only recently by scientists. In contrast, nothing is known of the northern region of the ridge, which is characterised by a prominent, steep-sided seamount that has a flat circular summit at 240 m and width of ~20 km. This seamount is some 200 km south of Madagascar and unnamed; it is referred to here as the MAD-Ridge seamount. MAD-Ridge is the shallowest of a constellation of five deeper (>1200 m) seamounts on that part of the ridge, all within the EEZ of Madagascar. It lies in a highly dynamic region at the end of the East Madagascar Current, where mesoscale eddies are produced continuously, typically as dipoles. The Madagascar Ridge appears to be an area of great productivity, as suggested by the foraging behaviour of some tropical seabirds during chick-rearing and a longline fishery that operates there. The third seamount, La Pérouse, is located between Réunion Island and Madagascar. With a summit 60 m below the sea surface, La Pérouse is distinct from MAD-Ridge and Walters Shoal; it is a solitary pinnacle surrounded by deep abyssal plains and positioned in an oligotrophic region with low mesoscale activities. The overall aim of the MADRidge project was to examine the flow structures induced by the abrupt topographies, and to evaluate whether biological responses could be detected that better explain the observed increased in fish and top predator biomasses. The MADRidge project comprised a multidisciplinary team of senior and early career scientists, along with postgraduate students from France, South Africa, Mauritius and Madagascar. The investigation was based around three cruises using the French vessels RV Antea (35 m) and RV Marion Dufresne (120 m) in September 2016 (La Pérouse), November-December 2016 (MAD-Ridge) and May 2017 (Walters Shoal). This manuscript presents the rationale for the MADRidge project, the background, a description of the research approach including the cruises, and a synopsis of the results gathered in the papers published in this Special Issue.

Observation of a mesoscale eddy dipole on the northern Madagascar Ridge: Consequences for the circulation and hydrography in the vicinity of a seamount

Based on satellite and in situ data, the dynamic characteristics and vertical structure of a surface intensified mesoscale eddy dipole recently expelled from the South East Madagascar Current (SEMC) is described for the first time. The dipole was surveyed 250 nautical miles south of Madagascar between 14 and 23 November 2016, during west-east and south-north transects carried out over the northern Madagascar Ridge. The dipole consisted of two counter-rotating vortices of similar size (100 km) and intensity (0.7 f), and an intense southwestward jet (150 cm s-1) in the frontal region between the two eddies. The cyclonic eddy was lying on the western side of the anticyclonic eddy. With azimuthal velocities reaching 100 cm s-1 at the surface and decreasing slowly with depth (40 cm s-1 at -600 m), this dipole was defined as a highly non-linear (Ro ~ 0.7) isolated eddy-type structure (cβ ~ 11 cm s–1 and U/cβ ~ 0.7) capable of trapping and advecting water masses over large distances. The enhanced concentration of chlorophyll-a found in the cyclone relative to the anticyclone could be tracked back to the spin-up phase of the two eddies and attributed to eddy-pumping. The eddy cores were located above the pycnocline (1026.4 kg m-3), within the upper 600 m, and consisted of varieties of Subtropical Underwater (STUW) found within the SEMC. The STUW found in the anticyclone was more saline and oxygenated than in the cyclone, highlighting mixing with the inshore shelf waters from the southeastern coastal upwelling cell off Madagascar. Observations suggest that the dipole interacted strongly with the chaotic bathymetry of the region, characterized by a group of five seamounts lying between -240 m and -1200 m. The bathymetry blocked its westward advection, trapping it in the vicinity of one shallow seamount for more than 4 weeks, so enhancing the role of the eddy-induced velocities in stirring the surrounding water masses. Squeezed between the southern Madagascan shelf and the northern flank of the anticyclone, two filament-like dynamic features with very different water-mass properties could be observed on the south-north transect: i) one filament highly concentrated in chlorophyll-a demonstrating the capacity of the eddy to export shelf water offshore; ii) intrusions of southern-type STUW generally found south of the South Indian Counter Current (SICC) recirculating on the external flanks of the anticyclone. Although the observed circulation and hydrography were largely constrained by the presence of the mesoscale eddy dipole, unmistakable fine-scale dynamics were also observed in the vicinity of the MAD-Ridge seamount, superimposed onto the mesoscale eddy flow.

Ocean currents and gradients of surface layer properties in the vicinity of the Madagascar Ridge (including seamounts) in the South West Indian Ocean

This work is part of the MADRidge Project special issue which aims to describe pelagic ecosystems in the vicinity of three prominent shallow seamounts in the South West Indian Ocean: one here named MAD-Ridge (240 m below the surface) plus Walters Shoal (18 m) on the Madagascar Ridge, and La Pérouse (60 m) on the abyssal plain east of Madagascar. The three span latitudes 20°S and 33°S, some 1500 km. The study provides the background oceanography for the once-off, multidisciplinary snapshot cruise studies around the seamounts. As life on seamounts is determined by factors such as summit depth, proximity to the light layers of the ocean, and the ambient circulation, a first description of regional spatial-field climatologies (16–22 years) and monthly along-ridge gradients of surface wind (driving force), water column properties of sea surface temperature, mixed layer depth, chlorophyll-a and eddy kinetic energy, plus ocean currents is provided. Being relevant to many applications in the study domain, these properties in particular reveal contrasting environments along the Madagascar Ridge and between the three seamounts that should drive biological differences. Relative to the other two seamounts, MAD-Ridge is in the more extreme situation, being at the end of the East Madagascar Current, where it experiences sturdy, albeit variable, currents and the frequent passing of mesoscale eddies.

A new species of Holophloeus Jordan (Coleoptera: Anthribidae) from eastern Madagascar with ecological notes on it and H. tuberosus (Fairmaire, 1897)

A new species, Holophloeus loebli Trýzna Baňař sp. nov. (Anthribidae: Anthribinae: Discotenini), from east Madagascar is described. Male genitalia are studied and illustrated, and color photographs are provided. A comparison is provided with the other known Madagascan species of the genus, H. tuberosus (Fairmaire, 1897). Ecological notes, including color photographs of habitats, on H. loebli and H. tuberosus are provided.