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Dan Janzen proposed in a paper in 1977 (loc. cit.), that a clone of aphids and for that matter dandelions consists, respectively, of one large ‘super-organism’. In effect a single evolutionary individual able to exploit resources over an expanded geographical range, and sometimes with aphids also, a wider range of resources (different kinds of host plants), much more than if the organism concerned were a single individual. Such a view is of course based on the notion that an asexual lineage (clone) has strict genetic fidelity, that is to say, is genetically identical over its entire genome between clone mates. This seems a highly unlikely scenario and indeed, modern molecular markers have revealed a plethora of mutational events within such so-called clones. Here in this talk I provide evidence from aphids that they are not ‘perfect forms’ but rather show a range of variations, including evidence of hybridization events, and that they can and do adapt to environmental circumstances, sometimes swiftly. Hence that even as asexual lineages, aphids are able to exploit new ecological circumstances and flourish, e.g. host adapted forms, whilst some species, notably the highly polyphagous peach-potato aphid (Myzus persicae), have also evolved resistance to a range of pesticides, and by so doing, have managed to survive in the face of these poisons. However, there are fitness costs associated with such adaptation, more especially in the highly resistant aphids. Because of the variation and adaptation shown by particular aphid species and asexual lineages, they cannot be described as a single evolutionary unit in a ‘Janzenian’ sense. What they show is ecological plasticity and an ability to adapt quickly, in large part enhanced by their incredible rate of reproduction and population expansion. Some migrating winged aphids are constrained in their exploitation of new habitats by environmental factors – geographical, climatic and ecological, especially lack of suitable hosts. In contrast, some other aphid species have seemingly colonized large areas of the world (probably aided by human agency) so that deciding what a population is exactly is a difficult task. It may even be that certain ‘super clones’ detected using molecular markers have indeed spread far and wide, clones which appear to fit the description of being ‘general purpose genotypes’ in that they can feed on a range of plant hosts under a range of different geographical-climatic conditions. As such, they are nearest to Dan Janzen’s views, although here again, strict genetic fidelity is not necessarily proven, only accepted from the application of a limited number of markers, e.g. multilocus genotypes in the case of microsatellite markers.
The taxonomy of the Palaearctic ant genus Proformica Ruzsky, 1902 is confused and in need of revision. The type specimen for P. nasuta (Nylander, 1856), the type species of the genus, was from Beaucaire, southern France, and is presumably lost. Based on extensive sampling of Proformica nests in southern France, including the type locality, we show that the concept of P. nasuta has been erroneous for more than a century. We integrate information from the morphology of workers and sexual castes, DNA markers, and cuticular hydrocarbons to re-define species in southern France. This allowed us to provide a new, accurate description of P. nasuta and designate a neotype, as well as reference individuals for all castes. In addition, we propose a name, P. longipilosa sp. nov., for a species that since the end of the 19th century has mistakenly been included in P. nasuta.
Based on an integrative taxonomic approach, a new species of the genus Loxosceles Heineken & Lowe, 1832, is described from the state of Hidalgo, Mexico. Loxosceles tolantongo sp. nov. is described based on DNA barcoding using cytochrome c oxidase subunit 1 (CO1) and internal transcribed spacer 2 (ITS2), and morphology. For species delimitation, four molecular methods were implemented: 1) corrected p-distances under neighbor joining (NJ); 2) automatic barcode gap discovery (ABGD); 3) general mixed yule coalescent model (GMYC) and 4) Bayesian Poisson tree processes (bPTP). The new species morphologically resembles L. jaca, another species from Hidalgo, but there are morphological differences mainly in the tibiae of the male palp, the seminal receptacles of the females and also the high genetic p-distances. CO1 was more informative than ITS2 for the genetic separation; however, both concatenated genes (CO1 + ITS2) present robust evidence for species delimitation. Loxosceles tolantongo sp. nov. is considered a unique species for four reasons: 1) it can be diagnosed and distinguished by morphological characters (of the male palps mainly, but also of the seminal receptacles of the females); 2) the genetic p-distances with CO1 were high (>10%); 3) the molecular species delimitation methods were congruent under CO1 and CO1 + ITS2; and 4) under CO1 and CO1 + ITS2, the new species is a putative sister group of L. jaca + L. tenango.
A new species of epigean ricinuleid of the genus Pseudocellus Platnick, 1980 from El Triunfo Biosphere Reserve, Chiapas, Mexico is described. DNA barcoding utilizing mitochondrial cytochrome c oxidase subunit 1 (CO1) and morphology were used for species delimitation. Molecular analyses and species delimitation included four methods: 1) General Mixed Yule Coalescent model (GMYC), 2) Automatic Barcode Gap Discovery (ABGD), 3) Bayesian Poisson Tree Process (bPTP), and 4) Assemble Species by Automatic Partitioning (ASAP). All molecular methods and morphology were consistent in delimiting and recognizing the new species described herein. The average interspecific genetic distance (p-distance) among analyzed species of Pseudocellus was 11.6%. The species is described based on adult males and females: Pseudocellus giribeti sp. nov. This is the seventh species described from Chiapas, which holds the highest number of ricinuleids species for the country. The total number of described species of Pseudocellus from Mexico increases to 21, having the highest species diversity of known ricinuleids worldwide.