A new species of Falsopodabrus Pic characterized with geometric morphometrics (Coleoptera, Cantharidae)

Description of two new species of Ectinorus (Ectinorus) (Siphonaptera, Rhopalopsyllidae) from Argentina, including a morphometric approach

Two new species of fleas of genus Ectinorus (Siphonaptera: Rhopalopsyllidae) are described from sigmodontine rodents (Rodentia: Cricetidae) collected during a survey of small mammals in northwestern Argentina.The new species belong to the subgenus Ectinorus and can be distinguished from all other species of the subgenus by the characteristics of the modified abdominal segments and by the genitalia. Moreover, the male of Ectinorus (Ectinorus) disjugis is described for the first time and the finding of this flea parasitizing the rodent Akodon spegazzinii, constitutes a new flea-host association. A phylogenetic analysis of the genus Ectinorus, using traditional morphological characters and morphogeometric data, is presented to support the erection of the new species of Ectinorus. An identification key for all species of Ectinorus is also provided. Our study increases to 38 the total number of species of the subgenus Ectinorus, and to 20 the number for Argentina. Phylogenetic analyses reveal that Ectinorus is monophyletic but the subgenera are not. This study offers a new interpretation of morphological diversity within the genus as well as an evaluation of hypotheses about their relationships.

Does the exposure of parental female adults of the invasive Trogoderma granarium Everts to pirimiphos-methyl on concrete affect the morphology of their adult progeny? A geometric morphometric approach

Insecticidal applications may result to morphological deformations upon exposed insects or their offspring production. In the present study, we tested whether pirimiphos-methyl can induce deformities to wings of progeny production of the invasive khapra beetle, Trogoderma granarium (Coleoptera: Dermestidae) when its parental female adults have been treated with this organophosphorus active ingredient. For that purpose, we analysed both elytra and hindwings of both sexes of T. granarium progeny production by using the geometric morphometrics method. Our results showed that the wings of progeny of the pirimiphos-methyl-treated T. granarium parental female adult individuals suffered certain changes in their usual shape depending on size. Deformations occurred on both pairs of wings, but changes were more noticeable on the hindwings. A longer than 5-h exposure of parental female adults to pirimiphos-methyl, resulted in progeny with more deformed wings than in those individuals emerged after the exposure of their parental female adults in shorter periods on the toxicant. Generally, wings of both sexes were sensitive to pirimiphos-methyl, distinguishing the control group from the insecticidal treatments. The existence of deformed adults could be a useful indicator of earlier insecticidal applications as surface treatments and/or grain protectants in the storage facilities.

Hind wing variation in Leptura annularis complex among European and Asiatic populations (Coleoptera, Cerambycidae)

The ability to quantify morphological variation is essential for understanding the processes of species diversification. The geometric morphometrics approach allows reliable description of variation in animals, including insects. Here, this method was used to quantify the morphological variation among European and Asiatic populations of Lepturaannularis Fabricius, 1801 and its closely related species L.mimica Bates, 1884, endemic for Japan and Sakhalin islands. Since the taxonomic status of these two taxa is differently interpreted by taxonomists, they are collectively called “Lepturaannularis complex” in this paper. The analysis was based on the measurements of hind wings of 269 specimens from six populations from Europe and Asia. The level of morphological divergence between most of continental European and Asiatic populations was relatively small and proportional to the geographic distance between them. However, distinct morphotype was detected in Sakhalin Is. and Japan. These data confirm the morphological divergence of the endemic L.mimica species. Obtained results highlight the potential of the geometric morphometric method in studying morphological variation in beetles.

A potential pitfall in studies of biological shape: Does size matter?

The number of published studies using geometric morphometrics (GM) for analysing biological shape has increased steadily since the beginning of the 1990s, covering multiple research areas such as ecology, evolution, development, taxonomy and palaeontology. Unfortunately, we have observed that many published studies using GM do not evaluate the potential allometric effects of size on shape, which normally require consideration or assessment. This might lead to misinterpretations and flawed conclusions in certain cases, especially when size effects explain a large part of the shape variation. We assessed, for the first time and in a systematic manner, how often published studies that have applied GM consider the potential effects of allometry on shape. We reviewed the 300 most recent published papers that used GM for studying biological shape. We also estimated how much of the shape variation was explained by allometric effects in the reviewed papers. More than one-third (38%) of the reviewed studies did not consider the allometric component of shape variation. In studies where the allometric component was taken into account, it was significant in 88% of the cases, explaining up to 87.3% of total shape variation. We believe that one reason that may cause the observed results is a misunderstanding of the process that superimposes landmark configurations, i.e. the Generalized Procrustes Analysis, which removes isometric effects of size on shape, but not allometric effects. Allometry can be a crucial component of shape variation. We urge authors to address, and report, size effects in studies of biological shape. However, we do not propose to always remove size effects, but rather to evaluate the research question with and without the allometric component of shape variation. This approach can certainly provide a thorough understanding of how much size contributes to the observed shaped variation.