La Digue Research Articles

Imperturbatia griffithsi n. sp. and new records for Careoradula perelegans (E. von Martens, 1898) in Seychelles (Mollusca: Gastropoda: Streptaxidae)

New records of Seychelles Streptaxidae are reported. These comprise new localities for Careoradula perelegans on Praslin and La Digue islands, and the description of a new species from Praslin island: Imperturbatia griffithsi. This brings the streptaxid fauna of the granitic Seychelles islands to 20 species (18 endemic).

Evaluation of the limiting factors affecting the Seychelles Kestrel Falco araeus on Praslin Island (Seychelles) and considerations regarding a possible reintroduction of the species

Summary The Seychelles Kestrel Falco araeus is an endemic species confined to the larger granitic islands in the Seychelles archipelago. It is classified as “Vulnerable” and became extinct on Praslin and La Digue islands in the 1970s, leading to an attempt of reintroduction in 1977. This reintroduction was not a success, with the last census reporting only four breeding pairs on Praslin Island. Studies on the Seychelles Kestrel are very limited and dated, and a lack of data on the biology and ecology of the species has made it difficult to make a thorough assessment of the cause of the current decline of the Praslin population. In order to determine the limiting factors on Praslin we investigated the following ecological parameters: nest-site availability, trophic availability, predatory pressure, and interspecific competition. Data were collected on Mahé and Praslin islands in three habitats (i.e. urban, suburban, and forest areas) and compared to determine if limiting factors differed among islands, habitats, and islands*habitat. We only found a significant difference in nest-site availability, with Praslin showing a marked lack of nesting cavities. Breeding pairs on Praslin are probably forced to nest in suboptimal sites. Indeed, the breeding success rate on Praslin is very low, and most of the nests there fail. The Seychelles Kestrel population on Praslin is in decline and cannot be sustained without human intervention. Such an intervention must take into account the ecological parameters highlighted in the present study.

The Phalangopsidae crickets (Orthoptera, Grylloidea) of the Seychelles Archipelago: Taxonomy of an ecological radiation.

The Phalangopsidae crickets (Grylloidea) of the Seychelles are examined following extensive field sampling on several main islands of the archipelago (Mah, Silhouette, Praslin, La Digue). Despite the small area of these islands, six genera (12 species) are documented, including one new genus and five new species. The type species of the genus Seychellesia Bolivar, 1912 is transferred to the genus Paragryllodes Karny, 1909 as Paragryllodes nitidula (Bolivar, 1912) n. comb. The other species described in Seychellesia are transferred to the genus Seselia Hugel Desutter-Grandcolas, n. gen., as Seselia longicercata (Bolivar, 1912) n. comb. and Seselia patellifera (Bolivar, 1912) n. comb. Two new species are also described in the genus Seselia Hugel Desutter-Grandcolas, n. gen., Seselia coccofessei Hugel Desutter-Grandcolas, n. gen., n. sp. (type species of the genus) and Seselia matyoti Hugel Desutter-Grandcolas, n. gen., n. sp. The genera Phaeogryllus Bolivar, 1912 and Phalangacris Bolivar, 1895 are redescribed, including Phalangacris ferlegro Hugel Desutter-Grandcolas, n. sp. and Phalangacris sotsote Hugel Desutter-Grandcolas, n. sp. that are new to science. The genus Gryllapterus Bolivar, 1912 is redescribed and transferred from the Landrevinae (Gryllidae) to the Cachoplistinae (Phalangopsidae). New tribes are defined for the genus Paragryllodes (Paragryllodini Hugel Desutter-Grandcolas, n. tribe) on the one hand, and for Seselia Hugel Desutter-Grandcolas, n. gen., Phalangacris, Phaeogryllus and Gryllapterus (Seselini Hugel Desutter-Grandcolas, n. tribe) on the other, using morphological characters and the results of molecular phylogenetic studies (Warren et al. 2019). Phaloria (Papuloria) insularis (Bolivar, 1912) (Phaloriinae) is redescribed and restricted to Mah, and its calling song is documented for the first time, while Phaloria (Papuloria) bolivari Hugel Desutter-Grandcolas, n. sp. is newly described from Silhouette. Identification keys are proposed for the genera of Seselini Hugel Desutter-Grandcolas, n. tribe, and for the species of Seselia Hugel Desutter-Grandcolas, n. gen. and Phalangacris. The confusion between the Mogoplistidae Ornebius succineus Bolivar, 1912 and the Phalangopsidae Heterotrypus succineus Bolivar, 1910 is discussed, and the name Subtiloria succineus (Bolivar, 1912) considered a nomen nudum.

New and recent records of hawk moths (Lepidoptera: Sphingidae) from Seychelles, with a description of a new insular subspecies

In this study, we examine a recent sample containing two hawk moth species (Lepidoptera: Sphingidae) from Praslin and Mahé, Seychelles. It was widely accepted that the hawk moth species Temnora peckoveri (Butler, 1876) has a disjunctive range covering Madagascar and the Inner Seychelles. However, the Seychelles population of what was thought to be Temnora peckoveri shares a set of diagnostic morphological differences from both this species and T. fumosa (Walker, 1856) in the male genitalia structure. In particular, it remotely resembles Temnora fumosa based on the structure of aedeagus but differs from T. fumosa and T. peckoveri with respect to the harpe shape. Based on this evidence, we describe Temnora fumosa seychellensis Bolotov & Spitsyn ssp. nov. as a subspecies with restricted range, being endemic to the Inner Seychelles. The range of this subspecies covers Praslin (first record), Mahé, Silhouette, La Digue, Cousine, and Denis. Additionally, we report on recent occurrences of Agrius convolvuli (Linnaeus, 1758) from Praslin (second record) and Mahé. The adult moths were recorded feeding on inflorescences of Dracaena reflexa var. angustifolia Baker (Asparagaceae) for the first time. Finally, we present a complete list of Temnora fumosa seychellensis ssp. nov. and Agrius convolvuli occurrences from Seychelles.

Myxomycete biodiversity on five islands of the Seychelles.

A survey of myxomycete diversity on five islands of the Seychelles yielded 105 species and 10 infra-specific taxa, which included 89 species on La Digue, 66 on Praslin, 63 on Mahé, 31 on Curieuse and 4 on Félicité. Among these records, 64 species are new for the Seychelles and together with data from the literature, 143 species of myxomycetes are now known for all of the Seychelles. Most collecting on all five islands was carried out in low elevation areas. Forty-four species (73% of all specimens of myxomycetes) were found in low-elevation localities, and among these were Arcyria helvetica, Dictydiaethalium dictyosporum, Echinostelium paucifilum, Physarum aeneum, Ph. echinosporum, Reticularia olivacea, and Stemonaria longa. From 54 species of plants used by myxomycetes as substrates, eight species provided 63% of the specimens of myxomycetes, with most samples recorded from Calophyllum inophyllum. On the basis of substrate type, myxomycetes were distributed as follows: 37% of specimens were collected on dead wood and decaying palm stems, 16% on the bark and stems of living plants, 25% on ground litter, and 22% on aerial litter. A comparison of the assemblages of myxomycetes found in zones with different levels of human impact indicated that 84 species were found in forests, 74 in anthropogenic areas, and 62 in recreational coastal areas. The Seychelles provide a good background for a high level of myxomycete diversity, as a consequence of favorable climatic conditions and their location between Asia and Africa.

How to organise limited space: Micro-regionalisation of La Digue island (Seychelles)

Abstract Islands, especially small ones, are commonly studied as microcosms of natural and social processes. In this article, La Digue island (10 km2) in the Seychelles archipelago was treated as such. An attempt was made to analyse the significance of the natural environment for the features of spatial development under conditions of intense globalisation. For this purpose, functional micro-regions were determined, along with their genesis and evolution. Spatial dynamics and individual features of space are presented as chorème (Brunet 1986). The analysis was based on data from a library query and field observation and field studies in July 2018. Twelve functional regions were determined. Analysis of the distribution and evolution of their functions reveals a high dependence on natural environmental features, especially topography, and thus confirms (at the scale in question) a geographical determinism.

The Epidemiology and Impact of Chronic Rhinosinusitis upon Populations in Seychelles: An analysis of data from primary health facilities across Mahé, Praslin and La Digue

The Epidemiology and Impact of Chronic Rhinosinusitis upon Populations in Seychelles: An analysis of data from primary health facilities across Mahé, Praslin and La Digue

An annotated checklist of myxomycetes from the Seychelles Islands, Indian Ocean

The checklist provided herein contains 143 species and infra-specific taxa of myxomycetes representing six orders, 12 families and 29 genera known from the Seychelles Islands. These records are the result of 878 field collections and 468 samples processed with the use of the moist chamber techinque. The overall study involved expeditions to the granitic group of islands Mahé, Praslin, La Digue, Curieuse, Félicité, and data from the literature for the coral Aldabra atoll. The taxonomic structure of the myxomycete biota for the islands studied indicates a predominance of members of the order Physarales (74 taxa). Th e main genera are <em>Physarum</em> (38 species and two varieties), <em>Didymium</em> (17 species), <em>Cribraria</em> (11 species), <em>Arcyria</em> (eight species) and <em>Stemonitis</em> (six species and two varieties). For all six islands only a single species of myxomycete (<em>Physarum crateriforme</em>) was shared in common. For the total assemblage of species recorded from all of the islands, 4% species were abundant, 12% species were common, 29% were found occasionally, 42% were rare, and 13% species had only a single record. The most abundant species were <em>Arcyria cinerea</em>, <em>A. denudata</em>, <em>Diderma effusum</em>, <em>Hemitrichia calyculata</em>, <em>Physarum compressum</em>, and <em>P. melleum</em>. Based on data from 50 different localities with 90 collecting plots, 32% of all specimens were associated with coastal vegetation, 30% with lowland localities, 19% with intermediate forests, 9% with riverine forests, 8% with mountain forests, and only 2% with mangrove swamps. In general, this annotated checklist clearly shows that isolated tropical islands can support a diverse assemblage of myxomycetes.

Large-scale mitochondrial DNA analysis of native honey bee Apis mellifera populations reveals a new African subgroup private to the South West Indian Ocean islands

BackgroundThe South West Indian Ocean (SWIO) archipelagos and Madagascar constitute a hotspot of biodiversity with a high rate of endemism. In this area, the endemic subspecies A. m. unicolor has been described in Madagascar. It belongs to the African lineage, one of the four described evolutionary lineages in honey bees. Despite a long beekeeping tradition and several recorded European introductions, few studies have been carried out on the diversity and proportion of honey bee subspecies.In order to identify and define which evolutionary lineages and potential sub-lineages are present in the SWIO, the COI-COII intergenic region and the ND2 gene of the mtDNA were sequenced in honey bee colonies from three archipelagos. An extensive sampling (n = 1184 colonies) was done in the Mascarene (La Réunion, Mauritius, Rodrigues), Seychelles (Mahé, Praslin, La Digue) and Comoros (Grande Comore, Mohéli, Anjouan, Mayotte) archipelagos. Islands genetic diversity was compared to newly sampled populations from Madagascar, continental African and European populations.ResultsAfrican lineage haplotypes were found in all islands (except for Rodrigues). Madagascar, Comoros and Seychelles had 100% of A lineage, 95.5% in La Réunion and 56.1% in Mauritius. Among all African colonies detected in the SWIO, 98.1% (n = 633) of COI-COII haplotypes described the presence of the subspecies A. M. unicolor. Both genetic markers revealed i) a new private AI mitochondrial group shared by the SWIO archipelagos and Madagascar distant from continental populations; ii) the private African haplotypes for each island suggested diversity radiation in the archipelagos; iii) the detection of the Comoros archipelago as a possible contact area between insular and continental African populations.The exotic European C and M lineages were only detected in the Mascarene archipelago, but striking differences of proportion were observed among islands. Merely 4.6% of European colonies were found in La Réunion whereas Mauritius cumulated 44%. Here, among the 84 observed COI-COII haplotypes, 50 were newly described including 13 which were private to the SWIO archipelagos and Madagascar. Similarly, 24 of the 34 found ND2 haplotypes were novel which included six haplotypes particular to the SWIO populations.ConclusionA new African subgroup was described in the SWIO region with mitochondrial genetic evidence that A. m. unicolor is the indigenous subspecies of the archipelagos surrounding Madagascar.

Investigating the human—environment relationship of early intensive salt production: A case study from the Upper Seille Valley, Lorraine, northeast France

This paper presents the latest findings of multi-disciplinary research into the human—environment relationship of intensive Iron Age salt production in the Upper Seille Valley, Lorraine, northeast France. Investigations focus on the early Iron Age workshop “La Digue” (~625–500calBCE; Hallstatt D1–2), where high-resolution borehole sampling has been coupled with conventional excavation and geophysical surveying to establish direct linkages between intensive occupation and the alluvial environment of this site. Detailed insights into human—river interactions have been identified, enhancing current understanding of the environmental context and impact of this important early industry. The workshop's palaeogeographic setting has been reconstructed and new evidence for briquetage disposal practices has been identified, confirming that a close relationship existed between salt-making and the local hydrological regime. A large volume of briquetage waste (broken clay-fired salt-making equipment, ash and charcoal) was dumped into the river at La Digue, causing rapid and deliberate channel blockage, increasing the distance between the workshop and the river. This probably contributed to a localised increase in channel mobility and/or flooding whilst the workshop was active, producing challenging conditions for salt production. The workshop was abandoned following an intense flood event in ~500calBCE, coinciding with a major hydrological shift towards wetter floodplain conditions, likely arising from a combination of natural and anthropogenic factors. This study demonstrates the importance of understanding the environmental context of salt production and the roles of water management and briquetage disposal practices, which have been largely overlooked at other intensive salt making sites that employed the “briquetage technique”.

Hydraena Kugelann, 1794 (Coleoptera, Hydraenidae) from the Seychelles, Indian Ocean, with description of a new species.

Hydraena matyoti sp. n. (Coleoptera, Hydraenidae) is described from the Seychelles, Indian Ocean. Hydraena mahensis Scott, 1913 is redescribed. The latter is here recorded from La Digue for the first time. A key to the species of the genus Hydraena Kugelann, 1794 of the Seychelles is presented.

Genetic diversity of the honeybee (Apis mellifera L.) populations in the Seychelles archipelago

Abstract In the South‐West Indian Ocean, the honeybee Apis mellifera is found on several islands including the Seychelles archipelago. This archipelago is located 1120 km North of Madagascar, where the endemic African subspecies A. m. unicolor occurs. The genetic diversity of the honeybee populations in the Seychelles islands has never been studied, yet this species interacts with highly endemic and indigenous flora. A total of 186 honeybee colonies from the three main islands: Mahé, Praslin and La Digue were collected. In addition, 107 individuals from Madagascar (A. m. unicolor) and 49 from Italy (A. m. ligustica) were analysed as reference populations. The maternal lineages were assessed using PCR‐RFLP (n = 342) and sequencing (n = 121) of the mtDNA COI–COII intergenic region. Intra‐Seychelles nuclear genetic diversity and structure were analysed using 15 microsatellites while comparison with reference populations was done using 14 loci. All Seychellian colonies had mtDNA sequences characteristic of the African evolutionary lineage. Two sub‐lineages were detected: AI sub‐lineage (A1) was dominant (96.7%) on all islands and mostly represented by the subspecies A. m. unicolor, while Z sub‐lineage was observed in six colonies from two islands. No mtDNA characteristic of imported European lineages was detected. Nuclear genetic diversity was high and structured, suggesting restricted gene flow between islands of the archipelago. High nuclear similarities were found among the Seychellian and A. m. unicolor populations, yet significant genetic differentiation was observed. The A. m. ligustica reference population was highly differentiated from the Seychellian honeybee populations.

Evolutionary origins and genetic variation of the Seychelles treefrog, Tachycnemis seychellensis (Duméril and Bibron, 1841) (Amphibia: Anura: Hyperoliidae)

The hyperoliid frog Tachycnemis seychellensis, the only species of its genus, is endemic to the four largest granitic islands of the Seychelles archipelago and is reliant on freshwater bodies for reproduction. Its presence in the Seychelles is thought to be the product of a transoceanic dispersal, diverging from the genus Heterixalus, its closest living relative (currently endemic to Madagascar), between approximately 10–35Ma. A previous study documented substantial intraspecific morphological variation among island populations and also among populations within the largest island (Mahé). To assess intraspecific genetic variation and to infer the closest living relative(s) of T. seychellensis, DNA sequence data were generated for three mitochondrial and four nuclear markers. These data support a sister-group relationship between T. seychellensis and Heterixalus, with the divergence between the two occurring between approximately 11–19Ma based on cytb p-distances. Low levels of genetic variation were found among major mitochondrial haplotype clades of T. seychellensis (maximum 0.7% p-distance concatenated mtDNA), and samples from each of the islands (except La Digue) comprised multiple mitochondrial haplotype clades. Two nuclear genes (rag1 and tyr) showed no variation, and the other two (rho and pomc) lacked any notable geographic structuring, counter to patterns observed within presumably more vagile Seychelles taxa such as lizards. The low levels of genetic variation and phylogeographic structure support an interpretation that there is a single but morphologically highly variable species of Seychelles treefrog. The contrasting genetic and morphological intraspecific variation may be attributable to relatively recent admixture during low sea-level stands, ecophenotypic plasticity, local adaptation to different environmental conditions, and/or current and previously small population sizes. Low genetic phylogeographic structure but substantial morphological variation is unusual within anurans.

Recognition of two new species of freshwater crabs from the Seychelles based on molecular evidence (Potamoidea : Potamonautidae)

The Afrotropical freshwater crab genus Seychellum is endemic to the granitic Seychelles in the Indian Ocean (Mahé, Silhouette, Praslin, La Digue and Frégate). Here we describe two new cryptic species of Seychellum that represent two evolutionarily separate lineages of a previously monotypic genus. This raises to three the number of species of freshwater crabs known from Seychelles. Each species is endemic to either one island (Silhouette) or to a pair of islands (Mahé and Frégate, or Praslin and La Digue). The three species can be clearly distinguished as separate lineages by DNA analysis, haplotyping and examination of gonopod characters. The recognition of S. silhouette, sp. nov. (endemic to Silhouette) and S. mahefregate, sp. nov. (endemic to Mahé and Frégate) reduces the range of the type species, S. alluaudi (A. Milne-Edwards & Bouvier, 1893) to La Digue and Praslin. Both dispersal and vicariance may have played a role in shaping the present distribution patterns of the Seychellois freshwater crabs.

Tsunami in the Seychelles: Assessing mitigation mechanisms

A spatial statistical model determining the possible tsunami impact mitigation by coastal vegetation developed after the December 2004 earthquake event for Aceh, Indonesia, was adapted and tested under the conditions of the Seychelles in the western Indian Ocean to find out whether comparable protective effects of vegetation existed. The waves generated at the three main populated islands, Mahé, Praslin and La Digue averaged less than 2 m at the shoreline allowing assessment of effects of vegetation in mitigating impact of a low intensity tsunami event. Semi structured interviews with local witnesses of the event, field measurements of local features, as well as secondary data sources provided information on wave height at the shoreline, landscape characteristics as well as tsunami impacts inland, i.e. structural damage and maximum flood distance. Observation points at maximum flood distance and where damage occurred were geo-located and entered into a GIS. Vegetation density and resistance coefficients were determined on site and their spatial distribution through visual interpretation of Google Earth® pre tsunami imagery. Data was analyzed using a generalized linear mixed model, acknowledging the spatial distribution of data. As for Aceh, the results indicated that distance from the settlement to the shoreline was the most important factor to avoid adverse tsunami effects. In contrast to Aceh, a direct effect of coastal vegetation was not observed (p > 0.05). A significant protective effect, however, was apparent through sand dunes, stabilized by vegetation, reducing damage to buildings by up to 30% where initial water height at shoreline was 3 m. Maximum flood distance was not affected by sand dunes but was reduced (p = 0.013) by existing seawalls. A coastal planning that encompasses the promotion and protection of multi-use coastal vegetation, i.e. generating income through tourism, providing food products and protecting natural physical barriers is encouraged in order to enhance local resilience against natural wave events such as those of the 2004 tsunami.

The mosquitoes (Diptera: Culidae) of Seychelles: taxonomy, ecology, vectorial importance, and identification keys

BackgroundDuring recent periods, the islands of the Republic of Seychelles experienced many diseases such as dengue, chikungunya, Bancroft’s filaria and malaria. Mosquitoes transmit the agents that cause these diseases. Published information on mosquitoes in the Seychelles is notably dispersed in the literature. The maximum number of species obtained on a single field survey does not exceed 14 species.MethodsWe performed a comprehensive bibliographic review using mosquito and Seychelles as the key words, as well as conducted a mosquito field survey for larval and adult stages during the rainy season in December 2008. Sixteen sites were sampled on four granitic islands (Mahé, Praslin, La Digue and Aride) and six sites on coralline atolls in the extreme southwest of the country (Aldabra group).ResultsWe found published references to 21 mosquito species identified at least on one occasion in the Seychelles. Our collections comprised 18 species of mosquitoes, all of them from the subfamily Culicinae; no Anophelinae was found. We also confirm that Aedes seychellensis is a junior synonym of Ae. (Aedimorphus) albocephalus. The first records for Culex antennatus and Cx. sunyaniensis are presented from the country, specifically from Aldabra and Praslin, respectively. Based on a comparison of the taxa occurring on the granitic versus coralline islands, only three species, Ae. albocephalus, Cx. scottii and Cx. simpsoni are shared. Aedes albopictus appeared to exclude largely Ae. aegypti on the granitic islands; however, Ae. aegypti was common on Aldabra, where Ae. albopictus has not been recorded. The notable aggressiveness of mosquitoes towards humans on coralline islands was mainly due to two species, the females of which are difficult to distinguish: Ae. fryeri and Ae. (Aedimorphus) sp. A. The number of mosquito species collected at least once in the Seychelles is now 22, among which five species (Ae. (Adm) sp. A, Cx. stellatus, Uranotaenia browni. Ur. nepenthes and Ur. pandani) and one subspecies (Ae. vigilax vansomerenae) are considered as endemic. Two illustrated identification keys, one for adult females and the other for larval stages, are presented.ConclusionsThe knowledge of the culicidian fauna in the Seychelles has been notably updated. The number of mosquito species is relatively large with regards to land surface and distances to continental Africa, although the anophelines are totally lacking. The complex natural history of mosquitoes in the Seychelles provides examples of both vicariance- and dispersal-mediated divergences. They present superb examples for theoretical and applied island biology.

Reconstructing the colonisation and diversification history of the endemic freshwater crab ( Seychellum alluaudi) in the granitic and volcanic Seychelles Archipelago

The endemic, monotypic freshwater crab species Seychellum alluaudi was used as a template to examine the initial colonisation and evolutionary history among the major islands in the Seychelles Archipelago. Five of the “inner” islands in the Seychelles Archipelago including Mahé, Praslin, Silhouette, La Digue and Frégate were sampled. Two partial mtDNA fragments, 16S rRNA and cytochrome oxidase subunit I (COI) was sequenced for 83 specimens of S. alluaudi. Evolutionary relationships between populations were inferred from the combined mtDNA dataset using maximum parsimony, maximum likelihood and Bayesian inferences. Analyses of molecular variance (AMOVA) were used to examine genetic variation among and within clades. A haplotype network was constructed using TCS while BEAST was employed to date the colonisation and divergence of lineages on the islands. Phylogenetic analyses of the combined mtDNA data set of 1103 base pairs retrieved a monophyletic S. alluaudi group comprised three statistically well-supported monophyletic clades. Clade one was exclusive to Silhouette; clade two included samples from Praslin sister to La Digue, while clade three comprised samples from Mahé sister to Frégate. The haplotype network corresponded to the three clades. Within Mahé, substantial phylogeographic substructure was evident. AMOVA results revealed limited genetic variation within localities with most variation occurring among localities. Divergence time estimations predated the Holocene sea level regressions and indicated a Pliocene/Pleistocene divergence between the three clades evident within S. alluaudi. The monophyly of each clade suggests that transoceanic dispersal is rare. The absence of shared haplotypes between the three clades, coupled with marked sequence divergence values suggests the presence of three allospecies within S. alluaudi.

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The diversity of Indian Ocean Heterotardigrada

Information about Indian Ocean tardigrades is quite scarce and in most cases refers to species in coastal coralline sediment and occasionally in abyssal mud. The present data concern species found in the intertidal sand of Coco and La Digue Islands in the Seychelles, previously unsampled for tardigrades, as well as species in subtidal sediment found at depths ranging between 1 and 60 m off the shores of the Maldive Atolls. These sediments are all very similar and consist of heterogeneous coralline sand, moderately or scarcely sorted. Sixteen species (three new to science) were found in the Seychelles, belonging to Renaudarctidae, Stygarctidae, Halechiniscidae, Batillipedidae and Echiniscoididae. Diversity and evenness data are also interesting, with maximum values of H' = 2.59 and of J = 0.97. In the Maldives 25 species were found (two new to science) belonging to Neostygarctidae, Stygarctidae, Halechiniscidae and Batillipedidae. Such a number of species, despite the low percentage of tardigrade fauna (only 0.6% of the total meiofauna), contributes to the high values of both diversity and evenness, with H' ranging between 1.5 and 2.6 and J between 0.6 and 1. The Indian Ocean tardigrade fauna currently numbers 31 species of Arthrotardigrada and 2 species of Echiniscoidida. In the present study, Arthrotardigrada are the most abundant and all the families are present except Neoarctidae. Halechiniscidae is present with all the sub-families (except Euclavartinae), thus contributing to the high diversity values. Furthermore, 18 species, representing more than 50% of the total marine tardigrade fauna, are new records for the Indian Ocean, including five species new to science.

Another Seychelles endemic close to extinction: the emballonurid bat Coleura seychellensis

The only microchiropteran endemic to the granitic Seychelles, the sheath-tailed bat Coleura seychellensis, is categorized as Critically Endangered on the IUCN Red List. Using bat detectors, the islands of Mahé, Praslin and La Digue were surveyed to establish the current distribution of this species. Although two new roosts were discovered on Mahé, no bats were observed on Praslin and La Digue, and the range of C. seychellensis appears to have further contracted in the last 2 decades. A total of 19 C. seychellensis were counted emerging from or entering three roosts in boulder caves on Mahé during 18 evenings of observations. The bats foraged in open coastal habitat, some of it anthropogenic, and their echolocation calls were also characteristic of bats feeding in open habitat. This study provides no evidence that C. seychellensis is dependent on forest or wetland for foraging. Dietary analysis indicated that C. seychellensis feeds on Coleoptera, Lepidoptera and Diptera. A public education programme to highlight the conservation status of the bat and the consequences of roost disturbance is recommended, together with the urgent need for legal protection of the bats and their roosts.