Justin Gerlach

• MA DPhil (Zoology)
• Fellow at University of Cambridge

The story of the tree snails of the Pacific Islands spans 250 years of the history of biology as a science. This runs from Captain Cook's first voyage of exploration, through the start of evolutionary theory and the development of the science of genetics. 'Snailing round the South Seas' traces this history through the surprisingly central role play...

The IUCN Red List of threatened species is biased towards vertebrate animals, a major limitation on its utility for overall biodiversity assessment. There is a need to increase the representation of invertebrates (currently 21 % of species assessed on the List; \1 % of all inver-tebrates). A prioritisation system of terrestrial and fresh-water grou...

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).

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...

Tortoises (land turtles) are familiar animals and are generally assumed to be strict herbivores. Their ecological roles are most obvious in giant tortoise species which, due to their size and local abundance, play major roles as keystone species and ecosystem engineers1, 2, 3. In the Galápagos and Seychelles islands these species are known to play...

Since 1955 snails of the Euglandina rosea species complex and Platydemus manokwari flatworms were widely introduced in attempted biological control of giant African snails (Lissachatina fulica) but have been implicated in the mass extinction of Pacific island snails. We review the histories of the 60 introductions and their impacts on L. fulica and...

Since 1955 snails of the Euglandina rosea species complex and Platydemus manokwari flat-worms were widely introduced in attempted biological control of giant African snails (Lissachatina fulica) but have been implicated in the mass extinction of Pacific island snails. We review the histories of the 60 introductions and their impacts on L.

Since 1955 snails of the Euglandina rosea species complex and Platydemus manokwari flat-worms were widely introduced in attempted biological control of giant African snails (Lissachatina fulica) but have been implicated in the mass extinction of Pacific island snails. We review the histories of the 60 introductions and their impacts on L.fulica and...

Measuring progress toward international biodiversity targets requires robust information on the conservation status of species, which the International Union for Conservation of Nature (IUCN) Red List of Threatened Species provides. However, data and capacity are lacking for most hyperdiverse groups, such as invertebrates, plants, and fungi, partic...

Platydemus manokwari de Beauchamp, 1963 is an invasive flatworm found on islands in the tropics, especially in the Pacific Ocean. It has been implicated in the decline of several snail populations, including the extinction of some Partula species. Its predatory behaviour was investigated to quantify predation rates and elucidate climatic influences...

We report the presence of the land planarian Endeavouria septemlineata from Tahiti, French Polynesia, on the basis of a single specimen collected in 2017. Identification of the species was ascertained by external and internal morphology and DNA COI sequence. The finding is of importance for conservation, since this species is a predator of soil ani...

The partulid tree-snails of the Pacific Islands are today best known for their tragic recent history. Following the introduction of predatory snails a third of partulid species are now extinct and almost all others threatened with extinction. As most of these extinctions took place in a 20 year period this is one of the most dramatic rates of extin...

Report on a visit to the Bishop Museum, Hawaii to examine their amazing collection of Partula snails. Partula taxonomy now almost completely worked out. http://islandbidoversity.com/pnews.htm

The islands of the Western Indian Ocean (Madagascar and the small island groups of the Seychelles, Mascarenes and Comoros) are home to a remarkable diversity of animals and plants. Among the most notable are the tortoises, including some of the world’s largest, smallest and rarest species. Historically, at least ten species were present in the i...

A brief summary of research on the collections of the Academy of Natural Sciences, Philadelphia

During the dissection of 342 specimens of Moorean Partula for taxonomic research a study was made of the diet of these wild collected specimens. Gut contents were dissected out of 58 specimens, representing each species from several different valleys. The results of the dietary analysis are summarised here.

Significance Gardiner's Seychelle frog, one of the smallest terrestrial tetrapods, resolves an apparent paradox as these seemingly deaf frogs communicate effectively without a middle ear. Acoustic playback experiments conducted using conspecific calls in the natural habitat of the frogs provoked vocalizations of several males, suggesting that these...

The status of the tree Pisonia sechellarum F. Friedmann (Nyctaginaceae) endemic to the western Indian Ocean is reviewed. Five populations have been located: four in the Seychelles Islands (three on Silhouette Island and one on Mahe) and one on Mayotte. The species is associated with montane forest and ravine habitats and the genetic identity of dif...

Bioindicators, as taxa or functional groups, are widely used as indicators of environmental change, specific ecological factors or taxonomic diversity. The use of ecological, environmental and biodiversity indicators, is reviewed here. Although indicator taxa are considered to be generally unreliable as broad indicators of biodiversity, they may se...

The giant tortoises (Aldabrachelys or Dipsochelys) of the Indian Ocean Islands have been in decline since the first human settlement of the islands. They retain only a single natural population on Aldabra Atoll (and possibly Ile aux Cerfs, where tortoises are descendants of a mixture of indigenous and imported animals). Several additional wild popu...

Effective and targeted conservation action requires detailed information about species, their distribution, systematics and ecology as well as the distribution of threat processes which affect them. Knowledge of reptilian diversity remains surprisingly disparate, and innovative means of gaining rapid insight into the status of reptiles are needed i...

Molecular phylogenetic studies suggest that the genus Emballonura, a member of the Old World tribe Emballonurini (Family Emballonuridae), is paraphyletic. This genus has a broad distribution across islands in the Indo-Pacific, southern Asia, and Madagascar. The paraphyly is the result of the genus Coleura, known from sub-Saharan Africa, portions of...

The skeletal development of captive bred Seychelles-Aldabra giant tortoises (Dipsochelys/Aldabrachelys) was studied from late embryos to adults based on 93 specimens (45 embyronic). The pattern of ossification is described and the developments of the characters used to distinguish different morphotypes are investigated. The timing of ossification o...

Turtles, tortoises and terrapins are familiar animals, often kept as pets. Despite this familiarity it has only been in the last few years that their evolutionary origins have started to be revealed. Answers are starting to emerge to some of the most puzzling questions in vertebrate evolution, such as how did the turtle shell evolve and how have tu...

The status of the Seychelles frogs of the family Sooglossidae was investigated, using monitoring data from 1993-2010, climate data from 1998-2010 and studies of populations and local climate effects. Climate monitoring at each plot covered rainfall and temperature, with leaf wetness and soil moisture being monitored additionally at one site. Analys...

Growth patterns of captive-bred Seychelles–Aldabra giant tortoises (Aldabrachelys/Dipsochelys) were studied. This enabled the comparison of the development of 3 distinct morphotypes variously ascribed by different authors to 3 distinct species or a single, variable species (A./D. dussumieri/gigantea, arnoldi, and hololissa). Geometric morphometric...

Barychelidae is a pantropical mygalomorph family with 44 genera and 303 species (Platnick 2010). Sason Simon, 1887 is a genus of average-sized spiders with nine species distributed from Seychelles to Ponape, Palau Islands and eastern Australia (Raven 1986; Platnick 2010). Five species of this genus are known from two sexes, two species are known on...

Hypoxidia (Hypoxidaceae) is endemic to the Seychelles islands. The two species H. rhizophylla and H. maheensis have rarely been studied. The first studies of floral ecology are described based on 19 years of observations of cultivated (1992–1994) and wild (1998–2011) plants of H. rhizophylla and a single flowering event of cultivated H. maheensis....

The endemic plant Impatiens gordonii (Balsaminaceae) is one of the most threatened plants in the Seychelles; it is known from a small number of localities on the islands of Mahé and Silhouette. There have been a number of attempts to establish a new population on Silhouette. Between 2001 and 2005, five seedlings and 54 rooting stems were planted at...

Two terrapin subspecies are currently considered Seychelles endemisms and Critically Endangered according to IUCN criteria, with several conservation measures having been proposed and actively initiated in the recent years. We use molecular data to examine their population diversity and structure across the archipelago and find a complete lack of v...

Assessing Biodiversity Declines Understanding human impact on biodiversity depends on sound quantitative projection. Pereira et al. (p. 1496 , published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradati...

One species of Margarodidae (Coccoidea; Hemiptera; Insecta) has been recorded from the Seychelles islands: Icerya seychellarum. This is a widely introduced species and its original distribution is not known. The earliest records of the species are reviewed and it is concluded that this is probably a Western Indian Ocean species native to Seychelles...

Nyctaginaceae includes species that are predominantly non-mycorrhizal or form arbuscular or ectomycorrhiza. Root-associated fungi were studied from P. grandis and P. sechellarum roots collected respectively on the islands of Cousin and Silhouette in Seychelles. In addition fungal sporocarps were collected from the sampling area. Fungal symbionts we...

Only five lithobiomorph species are currently known from Seychelles, of which four belong to Australobius, which is one of the few genera in the Southern Hemisphere from the predominantly Northern Hemisphere Lithobiidae. The other family, Henicopidae, is known in the archipelago from only one species.

The granitic Seychelles are the only mid-oceanic islands of continental origin. Botanists have long focused on taxonomy, and plant communities were described in a qualitative way, based on simple observation. Therefore the altitudinal belts, their floristic characteristics and distribution are still poorly understood and conservation efforts focus...

This article was submitted without an abstract, please refer to the full-text PDF file.

This article was submitted without an abstract, please refer to the full-text PDF file.

We report a modeling study on habitat suitability and predicted distribution shifts of two species of Seychelles's freshwater turtles (Pelusios castanoides and Pelusios subniger) under a climate change scenario. We utilized data from the entire species distribution for modeling habitat suitability of the two species under current and future climate...

The granitic Seychelles are the only mid-oceanic islands of continental origin. Botanists have long focused on taxonomy, and plant communities were described in a qualitative way, based on simple observation. Therefore the altitudinal belts, their floristic characteristics and distribution are still poorly understood and conservation efforts focus...

The only known skull of the extinct Madagacan giant tortoise Dipsochelys abrupta is redescribed. It is similar to the other extinct Madagascar tortoise, Dipsochelys grandidieri, differing in the width of the vomer, in having a ridge on the occipital condyle, and in lacking diverging articular condyles of the quadrates.

The critically endangered Seychelles sheath-tailed bat Coleura seychellensis on Silhouette Island has been studied since 1997. The species occupies small caves in boulder fields in lowland woodland. Lepidoptera and Coleoptera dominate the diet, with a strong preference for the latter before and during the breeding season (November to April). Foragi...

Due to their permeable skin few amphibians are able to tolerate dry or salty conditions, a characteristic that has prevented most species from colonising oceanic islands. The most diverse oceanic island amphibian fauna is found in the Seychelles, an archipelago of about 115 granitic and coralline islands in the Indian Ocean, some 1,600km east of ma...

The Seychelles islands are notable for the high proportion of land area designated as National Parks (43%). These sites were designated with the aim of protecting water catchments and threatened species, mostly in the 1960s and 1970s. Their location does not take into consideration the likely impacts of climate change. It is anticipated that change...

The shores of the small coral cay on Desroches Atoll (Amirante Islands, Seychelles) span a range of conditions from relatively sheltered (along the atoll lagoonal coast) to very exposed (facing the Indian Ocean). This appears in no way to affect the occurrence of Scaevola, which dominates the entire coastline, but the frequencies of the other chara...

Key Biodiversity Areas (KBAs) are areas identified as being important for the conservation of biodiversity due to the presence of threatened species or habitats, or particularly high levels of biodiversity. They are a useful concept for setting site conservation priorities, combining other categories such as biodiversity hotspots, Important Bird Ar...

The population sizes of most Seychelles reptiles was assessed through transects and focal counts for squamates and literature reviews for chelonians. Population density estimation tested several different sampling methods: transects, focal counts, leaf-litter quadrats and drift fences. Transects were suitable for estimating populations of skinks an...

Long-term persistence of species characterized by a reduced effective population size is still a matter of debate that would benefit from the description of new relevant biological models. The island endemic specialist Drosophila sechellia has received considerable attention in evolutionary genetic studies. On the basis of the analysis of a limited...

Pelusios seychellensis (Family Pelomedusidae) is a small species similar to P. cas-taneus, distinguishable from other Seychelles mud turtles by its black carapace and plastron. It is known from only three specimens collected in the Seychelles on Mahé Island at the end of the 19th century, probably in an inland highland marsh. The species is current...

Islands are generally reported to have much higher extinction rates and levels of threat than continental areas. This perception is based largely on studies of vertebrates. A recent assessment of the biodiversity of the Seychelles islands enables the status of a range of taxonomic groups to be compared. A high proportion of the fauna is found to be...

In the Seychelles islands, all 3 endemic freshwater turtle taxa are either extinct (Pelusios seychellensis) or critically endangered (Pelusios castanoides intergularis and Pelusios subniger parietalis). These turtles are threatened by habitat loss, and monitoring of populations since 1996 has identified significant ongoing population declines. Drai...

A large part of this work was done by the late Daniel Lachaise. The energy and knowledge of our former colleague and teacher has been a major driving force behind much of the research into Drosophilidae of islands of the western Indian Ocean and, indeed, the rest of Africa and to him we owe an enormous debt.

The only known population of the Aldabra banded snail Rhachistia aldabrae declined through the late twentieth century, leading to its extinction in the late 1990s. This occurred within a stable habitat and its extinction is attributable to decreasing rainfall on Aldabra atoll, associated with regional changes in rainfall patterns in the late twenti...

The Seychelles harbour an endemic frog family, the Sooglossidae, currently containing two genera: Sooglossus, with three species, and Nesomantis with one species. These unique frogs are generally considered to be basal neobatrachians, although their relationships to other neobatrachian taxa, except the Nasikabatrachidae, remain unresolved. Our mole...

Since 1877 it has been assumed that human exploitation led to the extinction of all Indian Ocean giant tortoises except for the Aldabran Dipsochelys dussumieri. A taxonomic review in 1998 proposed that two further species survived in captivity. Some recent molecular studies question the validity of these taxa. All available evidence is re-examined...

The distribution and population densities of the Sooglossidae are evaluated. This family of frogs is endemic to the Seychelles islands where four species are restricted to high forests on the islands of Mahé and Silhouette. New distribution data are presented and habitat preferences quantified. Previously Sooglossus thomasseti was considered to be...

In December 2004 an Aldabra giant tortoise Dipsochelys dussumieri was washed ashore on the coast of east Africa, probably having been carried off the shore of Aldabra atoll, 740 km away. Although trans‐oceanic dispersal is assumed to be the mechanism by which tortoises and many other animals became established on islands throughout the world, this...

The location of and threats to biodiversity are distributed unevenly, so prioritization is essential to minimize biodiversity loss. To address this need, biodiversity conservation organizations have proposed nine templates of global priorities over the past decade. Here, we review the concepts, methods, results, impacts, and challenges of these pri...

The taxonomy of the Cyclophoridae and Pomatiasidae of the Seychelles islands is reviewed. Two species of Cyclophoridae are recorded: Cyathopoma blandfordi Adams, 1868 and C. picardense sp. new.. Three species of Pomatiasidae are recorded: Tropidophora pulchra (Gray, 1834), T. gardineri sp. nov. and T. ligata (Müller, 1774). The last species is reco...

The first successful captive maintenance of living terrestrial Geonemertes nemertines is reported. Behavioural observations are described, including the first data on diet in this genus. The species G. pelaensis is found to be a predator of small molluscs. In 1907 the Seychelles population was described as a distinct species, G. arboricola, largely...

The Seychelles sheath-tailed bat Coleura seychellensis is a Critically Endangered species endemic to the Seychelles islands of Mahé and Silhouette, with historical records from Praslin and La Digue islands. Published descriptions exist for only one active roost containing 32 bats. The present study located the species only in coastal boulder field...