Life in marine driftwood: The case of driftwood specialist talitrids

Driftwood in the sea – either floating or stranded on beaches – is a common feature particularly in temperate regions. Large quantities of driftwood, termed driftwood depositories, may collect at the mouth of small streams associated with marshes and have been present for some 120 millennia – since the origin of flowering plants.

Once marine driftwood begins to decay, it undergoes a specific succession. Firstly, it is colonized by salt tolerant, wood degrading fungi and bacteria, along with a few invertebrates able to digest wood by producing native wood degrading enzymes. The latter include gribbles (isopods) and chelurid amphipods.

Driftwood hoppers (talitrids), as well as isopods, chilopods, insect larvae, some ants and termites, comprize the secondary colonizers. They are all characterized by their inability to utilize driftwood directly. Instead, they rely on symbiotic microflora for digestive purposes.

Within all talitrids, the driftwood hoppers count as few as seven species, most likely because they are extremely difficult to locate and, therefore, discover and describe. Apart from living in tiny burrows, they measure between 13 and <6 mm, which makes the latter the smallest known talitrid.

Having reviewed the driftwood specialized talitrids, Dr. David Wildish of the St. Andrews Biological Station, Canada, concludes that all seven known species demonstrate dwarfism based on slow metabolism and growth. Their sexual development begins earlier compared to faster growing related species. All of them are also characterized with reduced eye size and absence of dorsal pigment patterns.

In his review article published in the open access journal Zoosystematics and Evolution, the scientist confirms that dwarfism in driftwood hoppers has evolved due to poor diet, in turn resulting in slowed metabolism and growth. A further adaptive challenge is the empty gribble burrow size occupied by talitrids (burrow diameter between 0.6 to 5 mm) with the smaller ones being more widespread. Larger talitrids can only complete their life cycle in the larger burrows.

“The size gradient in gribble burrow diameter provides a satisfactory explanation for serial dwarfism within the driftwood talitrids and is why each species becomes successively smaller,” explains the researcher.

Responsibility for first establishing the driftwood talitrid ecological grouping was made during graduate studies by David Wildish, London University, U.K., and Laura Pavesi, University of Rome, Italy. The two criteria for inclusion of a talitrid in the driftwood grouping was: behavioral fidelity to the occupied driftwood and that the food source was solely rotting driftwood (see references).

The larger talitrid family are small/medium in body length (< 30 mm) crustaceans with more than 400 species described in the world list. Ecological groupings within the family include marine/estuarine supralittoral wrack generalists, sand-burrowing, marsh-living and driftwood specialists. A few freshwater and many terrestrial species are also known.

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Original source:

Wildish DJ (2017) Evolutionary ecology of driftwood talitrids: a review. Zoosystematics and Evolution 93(2): 353-361. https://doi.org/10.3897/zse.93.12582

Origins of an enigmatic genus of Asian butterflies carrying mythological names decoded

A group of rare Asian butterflies which have once inspired an association with Hindu mythological creatures have been quite a chaos for the experts. In fact, their systematics turned out so confusing that in order to decode their taxonomic placement, scientists had to dig up their roots some 43 million years back.

Now, having shed new light on their ancestors, a team of researchers from the Biodiversity Institute of Ontario at University of Guelph, Agriculture and Agri-Food Canada and University of Vienna, published their findings in the open access journal Zoosystematics and Evolution.

CalinagaTogether, Drs. Valentina Todisco, Vazrick Nazari and Paul Hebert arrived at the conclusion that the enigmatic genus (Calinaga) originated in southeast Tibet in the Eocene as a result of the immense geological and environmental impact caused by the collision between the Indian and Asian subcontinents. However, the diversification within the lineage was far from over at that point. In the following epochs, the butterflies had to adapt to major changes when Indochina drifted away, leading to the isolation of numerous populations; and then again, when the Pleistocene climatic changes took their own toll.

To make their conclusions, the scientists studied 51 specimens collected from a wide range of localities spanning across India, South China, Laos, Vietnam, Myanmar and Thailand. For the first time for the genus, the authors conducted molecular data and combined it with an examination of both genitalia and wing patterns – distinct morphological characters in butterflies. While previous estimates had reported existence of anywhere between one and eleven species in the genus, the present study identified only four, while confirming how easy it is to mislabel samples based on earlier descriptions.

However, the researchers note that they have not sampled specimens from all species listed throughout the years under the name of the genus, so they need additional data to confirm the actual number of valid Calinaga species. The authors are to enrich this preliminary study in the near future, analysing both a larger dataset and type specimens in collaboration with the Natural History Museum of London that holds the largest Calinaga collection.

Despite being beautiful butterflies, the examined species belong to a genus whose name derives from the Hindu mythical reptilian creatures Nāga and a particular one of them – Kaliya, which is believed to live in Yamuna river, Uttar Pradesh, and is notorious for its poison. According to the Hindu myths, no sooner than Kaliya was confronted by the major deity Krishna, did it surrender.

“It seems that the modern taxonomy of Calinaga is in need of a Krishna to conquer these superfluous names and cleanse its taxonomy albeit after careful examination of the types and sequencing of additional material,” comment the authors.

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Original source:

Todisco V, Nazari V, Hebert PDN (2017) Preliminary molecular phylogeny and biogeography of the monobasic subfamily Calinaginae (Lepidoptera, Nymphalidae). Zoosystematics and Evolution 93(2): 255-264. https://doi.org/10.3897/zse.93.10744

New species of Brazilian copepod suggests ancient species diversification and distribution

A new species of groundwater copepod has been discovered in the rocky savannas of Brazil – an ecosystem suffering from heavy anthropogenic impact. Upon description, the tiny crustacean turned out to also represent a previously unknown genus. It is described by Dr. Paulo H. C. Corgosinho, Montes Claros State University, Brazil, and his team in the open access journal Zoosystematics and Evolution.

Prior to the discovery of the new species, named Eirinicaris antonioi, only one genus of its subfamily (Parastenocaridinae) had been recorded in the Neotropical region, which comes to show that related species had already spread across a huge range when the ancient supercontinent Gondwana split apart.

The new copepod measures about 0,300 mm and can be told apart by its morphological characteristics, including unusual sensorial structures at the rear part of the body, as well as unique sexual dimorphism.

The copepods of the family Parastenocarididae are adapted to life in groundwater, where they thrive between sand grains. These tiny creatures measure less than 1 mm, ranging between 0,200 and 0,400 mm in length. They can be found in various microbiotopes along rivers, lakes and human-made structures, such as dug or artesian wells. Alternatively, these copepods might be associated with mosses and other semi-terrestrial environments.

“This is the first species described from Goiás state, Central Brazil,” explain the authors. “With the discovery of this new species our knowledge about the geographical distribution of the copepod family Parastenocarididae is increased. Our project highlights the vast amounts of undiscovered biodiversity of the Brazilian rocky savannas, which are under high anthropogenic threat.”

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Original source:

Corgosinho PHC, Schizas NV, Previattelli D, Falavigna da Rocha CE, Santos-Silva EN (2017) A new genus of Parastenocarididae (Copepoda, Harpacticoida) from the Tocantins River basin (Goiás, Brazil), and a phylogenetic analysis of the Parastenocaridinae. Zoosystematics and Evolution 93(1): 167-187. https://doi.org/10.3897/zse.93.11602

Species new to science named after a ‘Dungeons & Dragons’ character

Focused on terrestrial gastropods, more commonly known as land snails, a joint team of biologists from the Natural History Museum of Stuttgart, Germany and the Zoology Museum of São Paulo, Brazil, have been researching the Brazilian caves. In their latest paper, published in the journal Zoosystematics and Evolution, the scientists describe the fauna from several caves in central Brazil, including a new tiny species named after a character from the popular fantasy tabletop role-playing game Dungeons & Dragons.

The team of Dr. Rodrigo Salvador, Daniel Cavallari and Dr. Luiz Simone encountered a rich assembly of species, several of which measured as much as a few millimetres. However, apart from filling important gaps in the knowledge of these tropical animals, they went even further, having discovered a land snail new to science. While it is not uncommon for studies dealing with the invertebrate fauna to end up describing new species, this minute mollusc (nearly 2 mm in length) attracted extra attention. The team which discovered the mollusc has named it Gastrocopta sharae, after Shar, the goddess of darkness, caverns and secrets in Dungeons & Dragons.

“It’s a fitting name for a tiny snail that lives hidden in the dark recesses of a cavern,” explain the authors. “If your knowledge of mythological beings seems to have failed you, do not fret. Usually biologists tend to honour Greek and Roman deities when naming species, but the goddess Shar has a more colourful background. She is from Dungeons & Dragons, the most famous role-playing game in the world, currently in its 5th edition and a staple of geek culture.”

Nevertheless, this is not the first time that Dungeons & Dragons has been immortalised in a species’ scientific name. In 2014, the very same team described another tiny snail, this time, one with a taste for deep waters, specifically those of the Atlantic Ocean. The scientists named it Halystina umberlee, after another Dungeons & Dragons goddess – Umberlee, who commands the harshness and perils of the sea.

The tropical snails are still poorly understood, although they are one of the most threatened animal groups – both by human activities and environmental changes. Moreover, since cave-dwelling invertebrates, in general, receive scarce attention from researchers, it should come as no surprise that cave-dwelling snails are even less known.

“Getting to know the fauna inhabiting each cavern is a demanding task, but a much-needed one,” note the researchers. “Caverns are known to have very fragile ecosystems and several lack proper protection, so works like ours are an important step for conservation efforts.”

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Original source:

Salvador RB, Cavallari DC, Simone LRL (2017) Taxonomical study on a sample of land and freshwater snails from caves in central Brazil, with description of a new species. Zoosystematics and Evolution 93(1): 135-141. https://doi.org/10.3897/zse.93.10995

Exceptional reproductive biology in extremely restricted critically endangered Nimba toad

The critically endangered Nimba toad is long known for its exceptional reproductive biology. The females of this unique species give live birth to fully developed juveniles, having for nine months continuously provided nutrition to the foetuses in the womb (matrotrophy). While live birth (viviparity) among frogs and toads is rather an exception than a common characteristic, matrotrophy, in place of alternatives such as the foetus being fed with yolk, unfertilized eggs, or smaller siblings, is what makes the Nimba toad one of a kind.

However, more than 40 years of research had not been comprehensively, accessibly and completely summarised. The gap has recently been filled with a new paper, published in the open access journal Zoosystematics and Evolution by German scientists Drs. Laura Sandberger-Loua and Mark-Oliver Rödel, both affiliated with Museum für Naturkunde, Berlin, and Dr. Hendrik Müller, Friedrich-Schiller-Universität Jena.

Studying the phenomenon, the scientists went through the literature published over four decades to gather the scattered details. They have also discussed the relationship between the toad’s reproductive biology and its specific habitat of merely 4 km² of high altitude grasslands located at a minimum of 1,200 m in the Nimba mountains, West Africa.

The climate of the area is characterised by a rainy season lasting from April to October and a dry season from November to February/March. These seasons are found to determine the activity of the Nimba toads. The amphibians are only active during the rainy season, when they give birth to their young, mate, and then find shelter underground, where they stay dormant during the dry season.

10489_ZSE_blogVisibly females can be distinguished from male Nimba toads by their differing cloaca and often larger size, compared to the males. Also, males show darker backs and, during most of their adult life, nuptial pads on their thumbs, which look like spiky swellings. This secondary sex characteristic, in its seasonal change linked to spermatogenesis, is used by the males to grasp tightly the female while mating.

In this species mating occurs without a copulatory organ. Instead, the sperm is transferred through connection of the cloacae, where the male’s swells and encloses the female’s cloaca. Furthermore, Nimba toads have a unique behavioural repertoire. Males crouch on their front legs and as soon as the female moves, follow her and grab her tightly in the groin. Due to the spiky nuptial pads, the males often injure their partner.

10489_ZSE_Image 3Giving birth in Nimba toads may take over two days, depending on the number of offspring, which can be up to 12 in older females – far fewer than the hundreds of eggs in most toad species. While giving birth, a female assumes a unique “birthing posture” to compensate for the lack of enough muscle power to expel juveniles. By the time the juveniles are ready to be born, they have already taken up nearly all the space in their mother’s body. The scientists conclude that the offspring play an active role in the process, as a juvenile toad’s death midway in the oviduct leads to the mother dying of sepsis.

Living exclusively in the Nimba mountains, and being listed as Critically Endangered, according to the IUCN, the studied toad is only one of the species restricted to the high altitude grasslands, which led to the declaration of the Nimba mountains as a World Heritage Site by UNESCO. Separated from other mountains, its inhabitants are isolated from external contacts, thus presumably leading to their evolutionary separation from related species. Furthermore, the toad’s unique reproductive biology is probably the result of this isolation, argue the authors.

In conclusion, the authors suggest that “it is likely that the harsh unpredictable environment and scarcity of open water promoted viviparity in Nimba toads, or supported the survival of this unique reproductive mode in these special and isolated conditions. Considering their complex life cycle, in which reproductive and seasonal cycles are tightly linked, understanding and protecting the Nimba toad’s threatened environment is of utmost importance.”

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Original source:

Sandberger-Loua L, Müller H, Rödel M-O (2017) A review of the reproductive biology of the only known matrotrophic viviparous anuran, the West African Nimba toad, Nimbaphrynoides occidentalis. Zoosystematics and Evolution 93(1): 105-133. https://doi.org/10.3897/zse.93.10489

New species of ground beetle described from a 147-year-old specimen

While new species are most commonly described based on recent field collections, undertaken at poorly explored places, some are identified in museum collections, where they have spent decades before being recognised as new to science. Such is the case of an unusually large and likely extinct ground beetle found at the Muséum national d’Histoire naturelle, Paris, whose story began in the distant 1860s with Dr. Eduard Graeffe’s trip to Samoa. Now, a century and a half later, the beetle is finally described by Dr. James K. Liebherr, Cornell University, USA, in the open access journal Zoosystematics and Evolution.

Much like the rest of the species within the genus, the beetle now going under the name Bryanites graeffi showed vestigial flight wings and other traits associated with flight-wing loss. However, at length of 16.2 mm it is the largest for the taxonomic group it is now assigned to. Although this may seem way too obvious for taxonomists to overlook, the beetle’s relatives are just as obscure. The Bryanites genus was previously known from two species represented by two specimens only, collected in 1924 from Savai?i Island by Edwin H. Bryan, Jr., Bernice P. Bishop Museum in Honolulu, during the Bishop Museum’s Whitney South Seas Expedition.

As a result, we now have three species representing an evolutionary radiation in Samoa, all known from single specimens collected long ago. The phylogenetics of these three species link them to other groups from Fiji and New Zealand.

What is the advantage of knowledge about species that existed some 90-150 years ago, but no longer? It might actually point us to the actual level of impact mankind has on natural ecosystems. The cause of the likely extermination of Bryanites graeffi might never be known with certainty, however, the colonization of many Pacific islands by the Polynesian rat has always been followed by the diminution or elimination of native insect species. Thus, we can add another likely victim to the list of species that have been adversely impacted by mankind’s commensal voyagers.

The species bears the name of its original collector to pay tribute to Dr. Graeffe and his hard work while collecting insects in the rain forest of Samoa well over a century ago .

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Original source:

Liebherr JK (2017) Bryanites graeffii sp. n. (Coleoptera, Carabidae): museum rediscovery of a relict species from Samoa. Zoosystematics and Evolution 93(1): 1-11. https://doi.org/10.3897/zse.93.10802