Pensoft blog - Part 70

New light on the controversial question of species abundance and population density

Inspired by the negative results in the recently published largest-scale analysis of the relation between population density and positions in geographic ranges and environmental niches, Drs Jorge Soberon and Andrew Townsend Peterson of the University of Kansas, USA, teamed up with Luis Osorio-Olvera, National University of Mexico (UNAM), and identified several issues in the methodology used, able to turn the tables in the ongoing debate. Their findings are published in the innovative open access journal Rethinking Ecology.

Both empirical work and theoretical arguments published and cited over the last several years suggest that if someone was to take the distributional range of a species – be it animal or plant – and draw lines starting at the edges of the space inwards, they would find the species’ populations densest at the intersection of those lines. However, when the team of Tad Dallas, University of Helsinki, Finland, analysed a large dataset of 118,000 populations, equating to over 1,400 species of birds, mammals, and trees, they found no such relationship.

Having analysed the analysis, the American-Mexican team concluded that despite being based on an unprecedented volume of data, the earlier study was missing out some important points.

Firstly, the largest dataset used by Tad and his team comprises observational data which had not required a certain sampling protocol or a plan. Without any standard in use, it is easy to imagine that the observations would be predominantly coming from people around and near cities, hence strongly biased.

Additionally, the scientists note that the analysis largely disregards parts of species’ geographic distributions for which there were no abundant data. As a result, the range of a species could be narrowed down significantly and its centroid – misplaced. Meanwhile, the population would appear denser on what appears to be the periphery of the area.

Similar issue is identified in the localisation of populations in the environmental space, where once again their range turned out to have been represented as significantly smaller, when compared to data available from the International Union for Conservation of Nature (IUCN) and the Global Biodiversity Information Facility (GBIF).

Further, a closer look into the supplementary materials provided revealed that the precision of the population-density data was not scalable with the climate data. As a result, it is likely that multiple abundance data falls within a single climate pixel.

In conclusion, the authors note that in order to comprehensively study the abundance of a species’ populations, one needs to take into consideration a number of factors lying beyond the scope of either of the papers, including human impact.

“We suggest that this important question remains far from settled,” they say.

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Original source:

Soberón J, Peterson TA, Osorio-Olvera L (2018) A comment on “Species are not most abundant in the centre of their geographic range or climatic niche”. Rethinking Ecology 3: 13-18. https://doi.org/10.3897/rethinkingecology.3.24827

Tiny moth from Asia spreading fast on Siberian elms in eastern North America

In 2010, moth collector James Vargo began finding numerous specimens of a hitherto unknown pygmy moth in his light traps on his property in Indiana, USA. When handed to Erik van Nieukerken, researcher at Naturalis Biodiversity Center (Leiden, the Netherlands) and specialist in pygmy moths (family Nepticulidae), the scientist failed to identify it as a previously known species.

*These are male specimens of the studied leaf mining moth Stigmella multispicata collected from Iowa, USA.*

Then, Erik found a striking similarity of the DNA barcodes with those of a larva he had recently collected on Siberian elm in Beijing’s botanical garden. At the time, the Chinese specimen could not be identified either.

In October 2015, Daniel Owen Gilrein, entomologist at Cornell Cooperative Extension of Suffolk County (New York, USA), received samples of green caterpillars seen to descend en masse from Siberian elm trees in Sagaponack, New York. He also received leafmines from the same trees.

Once they joined forces, the researchers did not take long to find out that the specimens from James Vargo and the caterpillars from New York belonged to one and the same species. The only thing left was its name.

Following further investigation, the scientists identified the moth as Stigmella multispicata – a pygmy moth described in 2014 from Primorye, Russia, by the Lithuanian specialists Agne Rociene and Jonas Stonis.

“Apparently, this meant that we were dealing with a recent invasion from East Asia into North America,” explains Erik.

Once the researchers had figured out how to identify the leafminer, they were quick to spot its existence in plenty of collections and occurrence reports from websites, such as BugGuide and iNaturalist.

With the help of Charley Eiseman, a naturalist from Massachusetts specializing in North American leafminers, the authors managed to conclude the moth’s existence in ten US states and two Canadian provinces. In most cases, the species was found on or near Siberian elm – another species transferred from Asia to North America.

Their study is published in the open access journal ZooKeys.

Despite the oldest records dating from 2010, it turned out that the species had already been well established at the time. The authors suspect that the spread has been assisted by transport of plants across nurseries.

“Even though Stigmella multispicata does not seem to be a real problem, it would be a good idea to follow its invasion over North America, and to monitor whether the species may also attack native elm species,” the researchers point out.

Interestingly, in addition to the newly identified moth, the Siberian elms in North America have been struggling with another, even more common, invasive leafminer from Asia: the weevil species Orchestes steppensis. The beetle had been previously misnamed as the European elm flea weevil.

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Original source:

van Nieukerken EJ, Gilrein DO, Eiseman CS (2018) Stigmella multispicata Rociene & Stonis, an Asian leafminer on Siberian elm, now widespread in eastern North America (Lepidoptera, Nepticulidae). ZooKeys 784: 95-125. https://doi.org/10.3897/zookeys.784.27296

Total of 21 new parasitoid wasps following the first ever revision of their genus

As many as twenty-one species of parasitoid wasps are described as new to science, following the first ever revision of their genus since its establishment back in 1893.

The study simultaneously updates the count of species within the genus (Chromoteleia) to 27 in total, produces a systematic revision of the world’s representatives of this group of wasps, expands their biogeographic knowledge, and clarifies their generic concept.

The monograph is published in the open access journal ZooKeys by a team of US and Canadian scientists, led by Hua-yan Chen, graduate student at the Ohio State University.

The wasps in the genus Chromoteleia are easily distinguished thanks to their large size in combination with their vivid colouration. Compared to other species in the family of platygastrid wasps, which normally measure merely 1 – 2 mm in length, the species in the studied genus range between 3 and 9 mm. Their uncommonly large, robust and elongated bodies is why the scientists assume that these wasps likely parasitise the eggs of orthopterans, such as grasshoppers, crickets and katydids.

A focal point in the study is the intriguing distribution of the wasps. While the genus is widespread throughout continental Mesoamerica, Central America and South America, and its distribution ranges from the Mexican state of Jalisco in the north all the way to Itapúa Department in Paraguay and Paraná in southern Brazil, the species C. congoana is a lone representative of the genus in Africa.

*The ‘lone’ African representative of the genus, Chromoteleia congoana.*

While dispersal from South America to Africa has been observed in the past in another genus of parasitoid wasps (Kapala), the scientists are not willing to reject the possibility of Chromoteleia wasps having been widely distributed across the Old World during a previous geological epoch. Such phenomenon, also known as a relict population, would not mean that the wasp group has subsequently ‘conquered’ the Neotropics and current species inhabiting the New World are rather remainders of once widespread insects.

To conclude their findings, the scientists examined specimens hosted in collections at twenty natural history institutions from around the globe, including the American Entomological Institute; American Museum of Natural History; Bernice P. Bishop Museum; California Academy of Sciences; Canadian National Collection of Insects; California State Collection of Arthropods; Florida State Collection of Arthropods; Instituto Alexander von Humboldt; Illinois Natural History Survey; Kansas University’s Natural History Museum; Museo del Instituto de Museo del Instituto de Zoologia Agricola; Museum National d’Histoire Naturelle; Museu Paraense Emílio Goeldi; Lund Museum of Zoology at Lund University; Triplehorn Insect Collection at the Ohio State University; South African Museum; Texas A&M University’s Insect Collection; Bohart Museum of Entomology; University of Colorado; and Smithsonian National Museum of Natural History.

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Original source:

Chen H-y, Talamas EJ, Valerio AA, Masner L, Johnson NF (2018) Revision of the World species of the genus Chromoteleia Ashmead (Hymenoptera, Platygastridae, Scelioninae). ZooKeys 778: 1-95. https://doi.org/10.3897/zookeys.778.25775

Towards untangling the ‘antennal grabbing’ phenomenon in mating cuckoo bees

Scientists report this behavior for the first time in the genus Nomada, following both lab and field observations in Germany

One can seldom spot a cuckoo bee, whose peculiar kleptoparasitic behaviour includes laying eggs in the nests of a certain host bee species, let alone a couple mating.

Nevertheless, German scientists – Dr. Matthias Schindler, University of Bonn, Michaela Hofmann and Dr. Susanne S. Renner of the University of Munich, and Dr. Dieter Wittmann, recently managed to record copulation in three different cuckoo bee species in the genus Nomada.

Intriguingly, in field and lab settings alike, the observed couples demonstrated the phenomenon the researchers called “antennal grabbing” where the male cuckoo bee winds his antennae around

*Insertion phase of copulation in a couple of the species Nomada flavoguttata. Note the male’s antennae spirally entangling the female’s.*

the female’s during copulation, thus transferring pheromones. Even though such behaviour is relatively common in Hymenoptera, this is the first known record for the genus Nomada.

While the particular biological reason for the “antennal grabbing” in different species remains unsettled, the scientists discuss the phenomenon in view of both previous hypotheses and their own observations in a new paper published in the open access Journal of Hymenoptera Research.

The courtship in Nomada cuckoo bee starts with the ‘swarming’ of males at willow shrubs and gooseberry or their patrolling in groups with males of the Andrena or Melitta species that will “foster” their offspring.

*Two males of the species Nomada flavoguttata patrolling at a blossom of a common dandelion.*

There is no aggression among the males. They were observed to rub their bellies and heads against the grass, in order to leave sexual pheromones, thus marking the “dating spot” for potential mates.

Earlier chemical studies of Nomada bees noted that the mandibular glands of males produce chemical compounds identical with those of their Andrena or Melitta hosts, leading to the suggestion that the males transfer pheromones that help the females mimic the odor of the host bee, and later enter its nest unnoticed to lay its eggs. An alternative explanation for the “antennal grabbing” is that males are spraying a substance onto the females to make them unattractive to other potential mates.

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Original source:

Schindler M, Hofmann MM, Wittmann D, Renner SS (2018) Courtship behaviour in the genus Nomada – antennal grabbing and possible transfer of male secretions. Journal of Hymenoptera Research 65: 47-59. https://doi.org/10.3897/jhr.65.24947

A new earless pygmy toad discovered on one of Angola’s most underexplored mountains

A new species of African pygmy toad was discovered during an expedition in 2016 to Angola’s second highest peak, the Serra da Neve Inselberg.

This small toad is distinct among its close relatives in lacking ears, though other more distantly related toads also lack ears. The new species is named Poyntonophrynus pachnodes, with the species name “pachnodes” being Greek for “frosty” in reference to both the name of the mountain (“Mountain of Snow” in Portuguese) and the cool temperatures at the higher elevations where it is found (nearly 1,500 m or 5000 ft above sea level).

The new species was discovered and described by an international team of scientists from the Instituto Nacional da Biodiversidade e Áreas de Conservação (Angola), Villanova University (USA), Florida Museum of Natural History (USA), University of Michigan-Dearborn (USA), Museu Nacional de Historia Natural e da Ciência (Portugal), and CIBIO – Centro de Estudos em Biodiversidade e Recursos Genéticos (Portugal), and published in the open access journal ZooKeys.

After spending three weeks in the field, the scientists returned from Angola to study the collected amphibians and reptiles through a combination of genetic and anatomical techniques.

The team used DNA sequences to determine the relationship of the new earless species to other African toad species. They also used high-resolution computed tomography scanning (CT scanning) to look at the skeletons of these frogs and determine the extent of ear loss.

While closely related to other pygmy toads, the new species from Serra da Neve was found to lack both external and internal parts of the ear related to hearing in other frogs and toads. The combination of genetic and anatomical information shows that this new pygmy toad recently evolved from an ancestor that had a completely formed ear.

The discovery and description of a new species of toad found only in the mountains of Angola is surprising. Most frogs and toads prefer moist environments such as lowland tropical rainforests or cool montane forests and grasslands.

In contrast, most African pygmy toad species can be found in the arid region of southwestern Africa, encompassed by Angola and Namibia. With the addition of this new species, there are now five pygmy toad species present exclusively in this region. Other species are found across other dry regions in southern and eastern Africa.

While most groups of African frogs are not rich in species in this region, the affinity for arid environments in African pygmy toads is more similar to groups of lizards, many of which have a number of species present only in this area.

Namibe Province is among the better-explored regions of Angola, but little is known of the species found on its isolated mountains, or inselbergs. The Serra da Neve Inselberg is of special interest because of its isolation from other mountains, which allows for the evolution of unique species, such as the new pygmy toad. The recent field research at Serra da Neve and the discovery of this new species of toad contribute to this mountain being considered a priority for conservation in the near future.

The new species is small (less than 31 mm in length) and coppery brown in colour. It lives among the rocks and leaves in dry open forests on Serra da Neve. While otherwise similar to other pygmy toads, the lack of ears makes this species distinct among its near relatives. It is unknown whether this species has a mating call and how it might hear. Many other frogs, including many species of toads, have also lost their ears over evolutionary time.

The discovery of this new species highlights the Serra da Neve as a potentially important center for Angolan biodiversity, but also suggests that African pygmy toads warrant further attention from scientists interested in the evolutionary loss of ears.

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Original source:

Ceríaco LMP, Marques MP, Bandeira S, Agarwal I, Stanley EL, Bauer AM, Heinicke MP, Blackburn DC (2018) A new earless species of Poyntonophrynus (Anura, Bufonidae) from the Serra da Neve Inselberg, Namibe Province, Angola. ZooKeys 780: 109-136. https://doi.org/10.3897/zookeys.780.25859

Right under our noses: A novel lichen-patterned spider found on oaks in central Spain

It happened again, a previously unknown spider species, whose home is a strongly humanised European country, appears to have been quietly and patiently waiting to get noticed until very recently.

Living on the trunks of oaks in Spain, the new species would have probably been spotted decades ago, had it not been for its sophisticated camouflage, which allows the small arachnid to perfectly blend with the lichens naturally growing on the tree.

Going by the name Araneus bonali, the new species was discovered on isolated trees at the borders of cereal fields by the scientists Eduardo Morano, University of Castilla-La Mancha, and Dr Raul Bonal, University of Extremadura. Their study is published in the open access journal ZooKeys.

Curiously enough, this is the same habitat, where the team found another new spider in 2016.

“How many new species remain unknown in these isolated oaks that once formed vast forests now becomes one even more intriguing question,” say the researchers.

“Anyone going for a walk around any village or park in central Spain would have been close to the new species. However, noticing it requires not only curiosity, but also a good sight, as its lichen-like colours make up an excellent mimicry.”

*Lichens growing on an oak trunk at the study site in central Spain.*

The similarity between the adults and the lichens that cover the oak trunks they inhabit is remarkable. Meanwhile, the greenish juveniles live amongst the green new shoots in the oak canopy until they reach maturity.

Whether the spider uses its mimicry to avoid predators or rather surprise its prey remains open for further investigation.

The description of this new species that belongs to the popular group of orb-weavers once again stresses the need of working harder on completing the list of spiders living in the Old World, such as the countries in the Mediterranean basin – a region that certainly keeps more taxonomic surprises up his sleeve.

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Original source:

Morano E, Bonal R (2018) Araneus bonali sp. n., a novel lichen-patterned species found on oak trunks (Araneae, Araneidae). ZooKeys 779: 119-145. https://doi.org/10.3897/zookeys.779.26944

Mosquito populations give a new insight into the role of Caucasus in evolution

We know that the Caucasus is a relatively large mountainous region, situated between Black and the Caspian seas. In its turn, it is divided into three subregions: Ciscaucasia, Greater Caucasus and Transcaucasia, also known as South Caucasus.

A closer look into the chromosome structure of mosquito larvae of a curious group of species (Chironomus “annularius” sensu Strenzke (1959)), collected from the three localities, has allowed Dr Mukhamed Karmokov of the Tembotov Institute of Ecology of Mountain territories at the Russian Academy of Science to figure out how the specificity of the Caucasian region has simultaneously unified its fauna geographically, yet has divided it evolutionarily. His paper is published in the open access journal Comparative Cytogenetics.

Having collected a sufficient amount of mosquito larvae, the researcher managed to study the chromosome structure, rearrangements and possible peculiarities of the separate Caucasian populations, in order to compare them.

Additionally, he analysed their relations to earlier known populations from Europe, Siberia, Kazakhstan and North America.

Amongst the curious peculiarities Karmokov identified in the chromosome structure of the studied larvae were some rearrangements which appear unique to Caucasus. Furthermore, he found that despite the close geographic proximity, the genetic distance between the Caucasian populations is quite significant, even While not enough to determine them as separate species, it could prove them as separate subspecies.

In conclusion, the scientist notes that the obtained data confirm that the Caucasian populations of the studied species have complex genetic structure and provide evidence for microevolution processes in the region.

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Original source:

Karmokov MKh (2018) Karyotype characteristics and chromosomal polymorphism of Chironomus “annularius” sensu Strenzke (1959) (Diptera, Chironomidae) from the Caucasus region. Comparative Cytogenetics 12(3): 267-284. https://doi.org/10.3897/CompCytogen.v12i3.25832

Beetle named after actress & biologist Isabella Rossellini for her series about animals

A new species of beetle with remarkably long genitalia that hint at a curious evolutionary “sexual arms race” has been described from Malaysian Borneo.

The new insect was named after actress and biologist Isabella Rossellini in honour of her stage shows and Webby Award-winning series of films about animal reproduction, featured on SundanceTV.

The species is described by scientists Menno Schilthuizen and Iva Njunjic of Naturalis Biodiversity Center and Universiti Malaysia Sabah, and Michel Perreau, Sorbonne Université, Paris. Their paper is published in the open access journal ZooKeys.

The new species, Ptomaphaginus isabellarossellini, finds a place among the 30 known species of round fungus beetles (subfamily Cholevinae) recorded by the authors from the island of Borneo. Of these, there are a total of 14 which had remained unknown to science until now.

The reason why the scientists named this particular species after the famous actress is its genitalia. The beetle’s penis carries a long, whip-like thread, called flagellum, whereas the female has a similarly long tube leading up to a sperm storage organ.

Lead author Menno Schilthuizen, who himself has previously released a simultaneously educative and entertaining book about the evolution of genitals, says that such exaggerated male and female genitalia often betray an “evolutionary sexual arms race”.

On the male side, natural selection favours longer genitalia because of the ability to directly reach the female’s sperm storage organ. However, female beetles would rather retain their right to favour the DNA of a certain mate over the rest. The upshot is that, over long periods of evolution, penises get longer and vaginas get deeper. Similar evolutionary genital exaggeration is also known in rove beetles and ducks.

“This is better than winning the Oscar,” says honoured Isabella Rossellini.

The Italian-born actress, filmmaker, author, philanthropist, and model has even featured the new beetle in her new Link Link Circus stage shows. Dealing with animal behaviour, the series will be touring theaters in Europe this fall.

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Original source:

Schilthuizen M, Perreau M, Njunjic I (2018) A review of the Cholevinae from the island of Borneo (Coleoptera, Leiodidae). ZooKeys 777: 57-108. https://doi.org/10.3897/zookeys.777.23212

How many sharks, chimaeras, skates, and rays inhabit Mexico?

Worldwide, Mexico is well-known for a lot of things: its cuisine, tequila, mariachis, pyramids, and beaches, as well as being the country with the most Spanish-speaking residents (more than 120 million people).

In contrast, however, little is known for the country’s chondrichthyan fauna: a class of fishes containing the sharks, chimaeras, rays, and skates.

To fill the gap in the knowledge of the Mexican marine fauna, scientists from the Instituto Politécnico Nacional – Centro Interdisciplinario de Ciencias Marinas (IPN-CICIMAR) conducted a multidisciplinary study on the extant species of the country’s Economic Exclusive Zone (EEZ) and, as a result, reported a total of 217 extant chondrichthyan species. Their findings are published in the open access journal ZooKeys.

In their updated taxonomic list, the team of Dr. José De La Cruz-Agüero, Dr. Jorge Guillermo Chollet-Villalpando, and Venezuelan graduate students Lorem González-González and Nicolás R. Ehemann report eight chimaeras, 111 sharks and 98 ray and skate species. These numbers equate to 18% of the world’s chondrichthyans.

Split between the Mexican coasts there are 92 species recorded from the Mexican Pacific and the Gulf of California, whereas 94 fishes are identified for the Gulf of Mexico and the Caribbean Sea. Additionally, 31 species are known from both coasts.

“The species richness will undoubtedly continue to increase, due to the current investigations in progress, as well as the exploration of deep-water fishing areas in the EEZ,” comment the scientists.

Considered to be primitive fishes, sharks, skates, chimaeras, and rays are believed to have been inhabiting the planet for the last 420-450 million years. To put it in perspective, the earliest evidence of our species – Homo sapiens – is pretty ‘young’ at 315,000 years.

Not only do these species are peculiar with their lack of a bony skeleton when compared to the more recently evolved fishes, but they also have an unusual digestive system, featuring a spiral valve, where the lower intestine is twisted like a corkscrew to increase the surface area. They don’t have a swimming bladder either. Further, there are about 650 extant species, whereas the known bony fishes are estimated to be over 35,000.

Most of the chondrichthyans are considered either ‘Critically Endangered’ (a classification a step below ‘Extinct’) or ‘Endangered’, according to the Red List of the International Union for Conservation of Nature (IUCN). The majority are also featured in the Convention on International Trade in Endangered Species.

As if to make matters worse, these fishes are also particularly susceptible to overfishing and have a low rate of growth and fecundity (females give birth to between 1 and 25 pups a year).

Original source:

Ehemann NR, González-González LV, Chollet-Villalpando JG, Cruz-Agüero JDL (2018) Updated checklist of the extant Chondrichthyes within the Exclusive Economic Zone of Mexico. ZooKeys 774: 17-39. https://doi.org/10.3897/zookeys.774.25028

New ‘scaly’ snails species group following striking discoveries from Malaysian Borneo

Six new species of unique land snails whose shells are covered with what look like scales have been described from the biodiversity hotspot of Malaysian Borneo by scientists Mohd Zacaery Khalik, Universiti Malaysia Sarawak, Kasper Hendriks, University of Groningen, Jaap Vermeulen, JK Art & Science, and Prof Menno Schilthuizen, Naturalis Biodiversity Center. Their paper is published in the open access journal ZooKeys.

Thanks to their conspicuous structures, the mollusks have been added to a brand new species group of land snails to be commonly known as the ‘scaly’ snails, so that they can be set apart from the rest in the genus Georissa. Why it is that only some of the species in the genus sport the unique ‘scales’, remains unknown.

Fascinated with the minute ‘scaly’ snail fauna of Borneo, the researchers carried out fieldwork between 2015 and 2017 to find out how these curious shells evolved. In addition, they also examined material deposited in museum and private snail collections.

Apart from DNA data, which is nowadays commonly used in species identification, the team turned to yet-to-become-popular modern tools such as 3D modelling, conducted through X-ray scanning. By doing so, the researchers managed to look at both the inner and outer surfaces of the shells of the tiny specimens from every angle and position, and examine them in great detail.

The researchers note that to identify the ‘scaly’ snails to species level, one needs a combination of both DNA and morphological data:

“Objective species delimitation based solely on molecular data will not be successful for the ‘scaly’ snails in Georissa, at least if one wishes for the taxonomy to reflect morphology as well.”

The six new species are all named after the localities they have been originally collected from, in order to create awareness for species and habitat conservation.

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Watch rotation and cross-section of the 3D models of the studied species here.

Original source:

Khalik MZ, Hendriks K, Vermeulen JJ, Schilthuizen M (2018) A molecular and conchological dissection of the “scaly” Georissa of Malaysian Borneo (Gastropoda, Neritimorpha, Hydrocenidae). ZooKeys 773: 1-55. https://doi.org/10.3897/zookeys.773.24878