Abdominal serial homologues of wings in Paleozoic insects.

The Late Paleozoic acquisition of wings in insects represents one of the key steps in arthropod evolution. While the origin of wings has been a contentious matter for nearly two centuries, recent evolutionary developmental studies suggest either the participation of both tergal and pleural tissues in the formation of wings1 or wings originated from exites of the most proximal leg podite incorporated into the insect body wall.2 The so-called "dual hypothesis" for wing origins finds support from studies of embryology, evo-devo, and genomics, although the degree of the presumed contribution from tergal and pleural tissues differ.3-6 Ohde et al.,7 confirmed a major role for tergal tissue in the formation of the cricket wing and suggested that "wings evolved from the pre-existing lateral terga of a wingless insect ancestor." Additional work has focused on identifying partial serially homologous structures of wings on the prothorax8,9 and abdominal segments.10 Thus, several studies have suggested that the prothoracic horns in scarab beetles,9 gin traps of tenebrionid and scarab beetle pupae,11,12 or abdominal tracheal gills of mayfly larvae1,13 evolved from serial homologues of wings. Here, we present critical information from abdominal lateral outgrowths (flaps) of Paleozoic palaeodictyopteran larvae, which show comparable structure to thoracic wings, consisting of cordate lateral outgrowths antero-basally hinged by muscle attachments. These flaps therefore most likely represent wing serial homologues. The presence of these paired outgrowths on abdominal segments I-IX in early diverging Pterygota likely corresponds to crustacean epipods14,15 and resembles a hypothesized ancestral body plan of a "protopterygote" model.

Evolution of sexual conflict in scorpionflies.

Sexual conflict - opposite reproductive/genetic interests between sexes - can be a significant driver of insect evolution. Scorpionflies (Insecta: Mecoptera) are models in sexual conflict research due to their large variety of mating practices, including coercive behaviour and nuptial gift provisioning. However, the role of palaeontology in sexual conflict studies remains negligible, namely due to the paucity of well-preserved fossils. Here, we describe three male scorpionflies from Cretaceous and Eocene ambers. The structure of notal and postnotal organs is analysed in extant and extinct forms; a depression below the base of the notal organ in different panorpid species spatially matches the anterior fold of the female's wing. Based on disparate abdominal configurations and correlations in extant relatives, we posit that each new fossil taxon had a different mating approach along a nuptial gifting-coercive spectrum. The Eocene specimen possesses extreme female clamping abdominal armature, suggesting a degree of sexual coercion greater than in any other known scorpionfly, extinct or extant. The fossil record of abdominal modifications in male scorpionflies documents a relatively late evolution (Eocene) of long notal organs indicating oppressive behaviour toward a female during mating. Our findings reveal a wider array of mating-related morphological specialisations among extinct Panorpoidea, likely reflecting more diversified past mating strategies and behaviours in this group, and represent first steps towards gaining a deep-time perspective on the evolution of sexual conflict over mating among insects.

Fossils Shed a New Light on the Diversity and Disparity of the Family Limoniidae (Diptera, Nematocera).

A new subfamily Drinosinae (Diptera, Limoniidae) is established with two fossil genera, Drinosa and Decessia gen. nov. with one new species, Decessia podenasi gen. et sp. nov. from Cretaceous Burmese amber. Additional description of Drinosa prisca is based on new material. A new subfamily shows unique reduction of radial veins combined with complete set of medial veins.

Molecular identification of Trichocera maculipennis, an invasive fly species in the Maritime Antarctic.

Trichocera maculipennis, an invasive Diptera, was described for the first time in Antarctica in 2006 in a sewage system of one of the scientific stations on King George Island, South Shetland Islands, and started to increase its distribution within the island. To date, only taxonomical description of this species, based on morphological data has been available, as there were no molecular data recorded. In the present study, we present two methods of molecular identification of this species-based on partial cytochrome c oxidase subunit I (COI) and 16S ribosomal RNA (16S) genes. An appropriate and easy-to-use assay for proper and fast identification of invasive species is a key requirement for further management decisions, especially in such a fragile environment as found in terrestrial Antarctica.

Ecomorphological diversification of the Late Palaeozoic Palaeodictyopterida reveals different larval strategies and amphibious lifestyle in adults.

The Late Palaeozoic insect superorder Palaeodictyopterida exhibits a remarkable disparity of larval ecomorphotypes, enabling these animals to occupy diverse ecological niches. The widely accepted hypothesis presumed that their immature stages only occupied terrestrial habitats, although authors more than a century ago hypothesized they had specializations for amphibious or even aquatic life histories. Here, we show that different species had a disparity of semiaquatic or aquatic specializations in larvae and even the supposed retention of abdominal tracheal gills by some adults. While a majority of mature larvae in Palaeodictyoptera lack unambiguous lateral tracheal gills, some recently discovered early instars had terminal appendages with prominent lateral lamellae like in living damselflies, allowing support in locomotion along with respiratory function. These results demonstrate that some species of Palaeodictyopterida had aquatic or semiaquatic larvae during at least a brief period of their post-embryonic development. The retention of functional gills or gill sockets by adults indicates their amphibious lifestyle and habitats tightly connected with a water environment as is analogously known for some modern Ephemeroptera or Plecoptera. Our study refutes an entirely terrestrial lifestyle for all representatives of the early diverging pterygote group of Palaeodictyopterida, a greatly varied and diverse lineage which probably encompassed many different biologies and life histories.

Trichocera maculipennis (Diptera)-an invasive species in Maritime Antarctica.

Antarctica, with its severe conditions, is poor in terrestrial fauna species. However, an increase in human presence together with climate change may cause an influx of non-native species. Here we report a significant increase in colonized area of one of the few known invasive species to date in Antarctica. Non-native flies of Trichocera maculipennis have been recently observed in the Admiralty Bay area on King George Island, South Shetlands Islands, West Antarctica, 10 years after its first record in Maritime Antarctica (Maxwell Bay, King George Island). Its rapid spread across the island, despite geographic barriers such as glaciers, indicates successful adaptation to local environmental conditions and suggests this species is invasive. The mode of life of T. maculipennis, observed in natural and anthropogenous habitat and in laboratory conditions, is reported. The following adaptations enabled its invasion and existence within the sewage system in Antarctic scientific stations: the ability to survive in complete darkness, male ability to mate on the substrate surface without prior swarming in flight, and adaptation of terrestrial larvae to survive in semi-liquid food. Possible routes of introduction to Antarctica and between two bays on King George Island are discussed, as well as further research leading to the containment and eradication of this species.

Paleozoic Nymphal Wing Pads Support Dual Model of Insect Wing Origins.

The appearance of wings in insects, early in their evolution [1], has been one of the more critical innovations contributing to their extraordinary diversity. Despite the conspicuousness and importance of wings, the origin of these structures has been difficult to resolve and represented one of the "abominable mysteries" in evolutionary biology [2]. More than a century of debate has boiled the matter down to two competing alternatives-one of wings representing an extension of the thoracic notum, the other stating that they are appendicular derivations from the lateral body wall. Recently, a dual model has been supported by genomic and developmental data [3-6], representing an amalgamation of elements from both the notal and pleural hypotheses. Here, we reveal crucial information from the wing pad joints of Carboniferous palaeodictyopteran insect nymphs using classical and high-tech techniques. These nymphs had three pairs of wing pads that were medially articulated to the thorax but also broadly contiguous with the notum anteriorly and posteriorly (details unobservable in modern insects), supporting their overall origin from the thoracic notum as well as the expected medial, pleural series of axillary sclerites. Our study provides support for the formation of the insect wing from the thoracic notum as well as the already known pleural elements of the arthropodan leg. These results support the unique, dual model for insect wing origins and the convergent reduction of notal fusion in more derived clades, presumably due to wing rotation during development, and they help to bring resolution to this long-standing debate.

Genus Trichocera in Morocco: first records from Africa and a new species (Diptera: Trichoceridae).

Till now only two species of the genus Trichocera, T. annulata and T. hiemalis, were recorded from north Africa. Herewith, we document seven species from Morocco, which extend distribution of the genus and the family to most southern localities of the western Palearctics in Africa (mountain ranges: the Rif, Middle Atlas and Beni Snassen). The following species were found: one new species in the nominate subgenus Trichocera (Trichocera) marocana, n. sp., and six of the subgenus Trichocera (Saltrichocera) (saltator, sardiniensis, pappi, annulata, regelationis, rufescens). The remarkably high share of the regelationis group of species in this southern fauna is discussed in view of tolerance of these species to warm climate.

New taxa of Tanyderidae (Diptera) from Eocene Baltic amber.

Macrochile hornei sp. nov. from Baltic amber (Upper Eocene) is described and illustrated. Podemacrochile gen. nov. is described with Podemacrochile baltica (Podenas, 1997) as type species. A key to the genera and species of Tanyderidae known from Baltic amber is presented.