Tag: entomology

The first long-haired ones: New wasp group proposed for 5 new species from India

Long accustomed to parasitising spider eggs, a large worldwide genus of wasps has as few as 24 known representatives in India. However, Dr. Veenakumari, ICAR-National Bureau of Agricultural Insect Resources, and her team have recently discovered five new species of these interesting wasps from different parts of the country. Because of their uniqueness and their strong resemblance to each other, as well to aid taxonomic studies they have been considered as constituting a group of their own. The discoveries and the suggestion of ‘the first long-haired ones’ species group are available in the open-access journal Deutsche Entomologische Zeitschrift.

Among the unique features that bring together the new five species, discovered by Drs. Veenakumari Kamalanathan, Prashanth Mohanraj and F. R. Khan, are the long hair-like structures along the margins of both of their wings. This is also the reason behind the authors’ choice of naming the proposed group adikeshavus, meaning ‘first one to have long hairs’ in Sanskrit.

Within this parasitic superfamily of wasps each group has been long accustomed to a specific host. The tribe to which the new five wasp species belong, for instance, is characterised by its exclusive preference for spider eggs. Parallel evolution accounts for the tiny wings of these wasps which allows them to slip through the silk strands of the egg sacs which are deposited in leaf litter by the spiders. Furthermore, all these species have a uniform length of 1 to 2 mm as a result of their getting used to parasitising relatively medium-sized spider eggs.

With over a thousand species supposed to exist in this genus the scientists suggest that their clustering into groups is a necessity to facilitate future studies.

The authors conclude that it is highly likely that this group of wasps will yield a much larger number of species of parasitoids attacking spider eggs in India.

###

Original source:

Kamalanathan V, Mohanraj P, Khan FR (2015) ‘The adikeshavus-group’: A new species group of Idris Förster (Hymenoptera, Platygastridae) from India, with descriptions of five new species. Deutsche Entomologische Zeitschrift 62(2): 247-260. doi: 10.3897/dez.62.6219

How did the stonefly cross the lake? The mystery of stoneflies recolonising a US island

Massive glaciers once covered an island in one of the Great Lakes, USA, leaving it largely devoid of life. Its subsequent recolonisation by insects triggered the curiosity of entomologist R. Edward DeWalt and graduate student Eric J. South of the Illinois Natural History Survey and Department of Entomology. Not only did they prove there were significantly fewer species, compared to the mainland, but also that smaller stonefly species appeared to be more capable of recolonizing the island. This study was published in the open-access journal ZooKeys .

Isle Royale is a large island and national park in the middle of Lake Superior, isolated from the mainland by 22 — 70 km distance. As recently as 8,000 — 10,000 years ago, glaciers completely covered the island making it almost uninhabitable.

Over the last 10 millennia mammals as large as moose and wolves, swam, floated, flew, or walked on ice bridges to the island. Therefore, it seemed logical that it was the larger size that allowed some species to cross the water. However, as far as stoneflies are concerned, the results turned out quite different.

“We sampled stoneflies (Plecoptera), mayflies (Ephemeroptera), and caddisflies (Trichoptera), because they are important water quality indicators. Our laboratory has expertise in the taxonomy and ecology of these important species and we know that national parks potentially provide us with wilderness quality conditions,” says DeWalt.

Being much better fliers, the mayflies and caddisflies did not show a particular relation between a species’ body size and their ability to recolonise the island. Conversely, stoneflies on the island were considerably smaller than their mainland counterparts.

“Stoneflies are clumsy fliers, especially the larger species. Large ones are not very aerodynamic and because of this they don’t have the energy reserves to cover the distance to the island. Few species of stoneflies can actually live in the lake, so most could not swim to the island,” explains DeWalt. “Mayflies and caddisflies, on the other hand, are known to be better fliers and tolerant of lake conditions, which would allow for more of the mainland species and similarly sized species to reach Isle Royale.

“Smaller stoneflies have probably used updrafts from the mainland and prevailing winds to get to the island,” the scientist suggests. “The wind just held them up until they reached the island.”

Future research is to use molecular techniques to identify the possible mainland origin for several species inhabiting Isle Royale National Park.

 

###

Original source:

DeWalt RE, South EJ (2015) Ephemeroptera, Plecoptera, and Trichoptera on Isle Royale National Park, USA, compared to mainland species pool and size distribution. ZooKeys 532: 137-158.doi: 10.3897/zookeys.532.6478

Saucer-like shields protect 2 new ‘door head’ ant species from Africa and their nests

Shaped like saucers, or concave shields, and covered with camouflaging layers of debris, the heads of two “door head” ant species are found to differentiate them as new taxa. They use their peculiar features to block the entrances of their nests against intruders like other predatory ants and invertebrates.

Being only the second case of such highly specialized morphologies discovered in Africa, the new representatives of the genus Carebara have been retrieved from sifted leaf-litter collected in rainforests in Western Kenya and the Ivory Coast.

Because of difficulties usually met while studying and identifying ants through dry specimens retrieved from standardised, passive collection methods, the two new species have so far been taxonomically misplaced. The new discovery was made by an international research team, led by Dr. Georg Fischer and Prof. Evan Economo, Okinawa Institute of Science and Technology Graduate University, Japan. The findings are available in the open access journal ZooKeys.

The “door head” ant individuals are a special worker subcaste that stands out among the other ant colony’s workers, who are responsible for vital tasks such as foraging and brood care. Dr. Georg Fischer and his colleagues analysed the herein described species with next-generation DNA sequencing to show that all different subcastes belong to the same species, despite their highly differing morphologies.

To assure the safety of their nestmates, the queen and the larvae, the two new species have evolved the special worker subcaste with heads covered by a layer of debris such as soil or even organic material, so that they blend in with their surroundings. While the shape of their heads allows them to perfectly fit into the nest entrance, the special armor shields their vulnerable eyes, antennae and mouthparts, as well as highly reduces the chance of enemies intruding into the nest.

The new Carebara species have been given the names C. phragmotica and C. lilith. The former is derived from the term phragmosis, in relation to the special function of their head shape, while the latter comes from the name of a female demon in Jewish mythology.

###

 

Original source:

Fischer G, Azorsa F, Hita Garcia F, Mikheyev AS, Economo EP (2015) Two new phragmotic ant species from Africa: morphology and next-generation sequencing solve a caste association problem in the genus Carebara Westwood. ZooKeys 525: 77-105. doi: 10.3897/zookeys.525.6057

Diggers from down under: 11 new wasp species discovered in Australia

After being mostly neglected for more than a hundred years, a group of digger wasps from Australia has been given a major overhaul in terms of species descriptions and identification methods. This approach has led to an almost 50% rise in the number of recognized species of these wasps on the continent. The study was published in the open access journal ZooKeys.

They call them with names like “Great Golden Digger” or “Great Black Wasp” in the US and there is a good reason behind it. However, some of these digger wasp species do not impress solely with their looks, but also with their wide range of distribution. Members of the wasp genusSphex can be found in almost every area of the world. Two researchers from the Museum für Naturkunde in Berlin, Thorleif Dörfel and Dr. Michael Ohl, have now reexamined the species diversity of Sphex in Australia.

More than a century has passed since the last revision of this group in the Down Under. Using pinned, dried individuals from museum collections all over the world, Dörfel and Ohl inspected over 900 specimens and recorded the morphological characters that they deemed most useful for species differentiation.

A very different lifestyle sets apart some species in the genus Sphex from the common idea that most people evoke on hearing the term “wasp”. Not being eusocial, each female constructs a separate, subterranean nest for their offspring, which is then filled with grasshoppers (or other insects, depending on the wasp species) that have been paralyzed by a sting as a food supply for the larvae. These wasps avoid contact with humans and generally do not show aggressive behavior toward us.

With 23 species known from Australia before this study, now the number has risen to 34. Most of these newly discovered species come from large quantities of material which had not been identified up to species level before. Dörfel and Ohl’s work also provides an up-to-date identification key, both in a regular and in an interactive form, that covers all known Australian species of the genus. Specifically designed to be easily usable and containing many helpful images, it can be utilized by anyone with even minimal prior training.

“Many insect groups are in urgent need of a revision or reclassification”, explained Thorleif Dörfel. “Our understanding of ecosystems depends on the ability to identify the species that are a part of them. The focus of this study was merely a single continent, but we are currently preparing a follow-up project in which we plan to examine representatives of this wasp genus from every major geographic area. Hopefully, this is going to help everybody who works on these animals, whether now or in another one hundred years.”

###

Original source:

Dörfel TH, Ohl M (2015) A revision of the Australian digger wasps in the genus Sphex(Hymenoptera, Sphecidae). ZooKeys 521: 1-104. doi: 10.3897/zookeys.521.5995