High-Throughput Sequencing for Life-History Sorting and for Bridging Reference Sequences in Marine Gerromorpha (Insecta: Heteroptera)

Accurate identification and association of larval specimens with adults is a major challenge in insect taxonomy. Fortunately, it is now possible for nonexperts to sort collections of bulk samples with DNA barcodes rapidly and cost-effectively. We demonstrate this process using nanopore barcoding of 757 marine insects (Insecta: Gerromorpha), of which 81% were nymphs and many samples did not have co-occurring adult males for specific identification. We successfully associated 738 specimens (97%) to nine gerromorphan species, which would have been impossible to identify using morphological characters alone. This improved ability to incorporate information from all life-history stages has led to greater precision of species distributional ranges—knowledge that will be crucial for a more complete understanding of marine insects. We also highlighted two distinct, nonoverlapping Gerromorpha COI sequence databases on GenBank—a consequence of using two different primer sets to amplify different regions of COI. This issue inevitably hinders species identification with DNA-based methods, particularly for poorly represented groups such as marine insects. We bridged these databases by analyzing full-length COI sequences. We believe this will inspire future studies to incorporate DNA-based methods for more adult–larval association studies and for enhancing existing genetic resources, especially in understudied groups.

Host phylogeny drives the structure and diversity of insect microbiota

Microorganisms have an enormous impact on most of the life that inhabits our planet. Insects are an excellent example, as research showed that several microbial species are essential for insect nutrition, reproduction, fitness, defence and many other functions. More recently, we assisted to an exponential growth of studies describing the taxonomical composition of bacterial communities across insects' phylogeny. However, there is still an outstanding question that needs to be answered: which factors contribute most in shaping insects' microbiomes? This study tries to find an answer to this question by taking advantage of publicly available sequencing data and reanalysing over 4,000 samples of insect-associated bacterial communities under a common framework. Results suggest that insect taxonomy has a wider impact on the structure and diversity of their associated microbial communities than the other factors considered (diet, sex, life stage, sample origin and treatment). Also, a survey of the literature highlights several methodological limitations that needs to be considered in future research endeavours. This study proofs the amount of collective effort that lead to the current understanding of insect-microbiota interactions and their influence on insect biology, ecology and evolution with potential impact on insect conservation and management practices.

Insect taxonomy can be difficult: a noctuid moth (Agaristinae: Aletopus imperialis) and a geometrid moth (Sterrhinae: Cartaletis dargei) combined into a cryptic species complex in eastern Africa (Lepidoptera)

The systematic position of a large and strikingly coloured reddish-black moth, Cartaletis dargei Herbulot, 2003 (Geometridae: Sterrhinae) from Tanzania, has remained questionable since its description. Here we present molecular and morphological evidence showing that Cartaletis dargei only superficially resembles true Cartaletis Warren, 1894 (the relative name currently considered a junior synonym of Aletis Hübner, 1820), which are unpalatable diurnal moths superficially resembling butterflies, and that it is misplaced in the family Geometridae. We transfer it to Noctuidae: Agaristinae, and combine it with the genus Aletopus Jordan, 1926, from Tanzania, as Aletopus dargei (Herbulot, 2003) (new combination). We revise the genus Aletopus to contain three species, but find that it is a cryptic species complex that needs to be revised with more extensive taxon sampling. Our results demonstrate the difficulties in interpreting and classifying biological diversity. We discuss the problems in species delimitation and the potential drivers of evolution in eastern Africa that led to phenotypic similarity in unrelated lepidopteran lineages.

The Prevalence of Single-Specimen/Locality Species in Insect Taxonomy: An Empirical Analysis

Although about two million species have been named, our knowledge about the biodiversity of many taxonomic groups remains inadequate and incomplete. There has been increased taxonomic effort for the discovery of more species and their geographical distribution information. During this process, species collected only from a single specimen/locality often appear. However, there are very few empirical data available to understand the current situation of single specimen/locality species in insect taxonomy. In this paper, we collected 1261 articles containing 4811 insect species from ZooKeys between 2009 and 2017, and we extracted data, including the publication date, number of specimens/locality, and DNA usage. Our analyses demonstrated that 21.53% and 21.74% of new species were described from only one specimen and one locality, respectively, and approximately half of all new species were published based on fewer than five specimens. Meanwhile, the rate of single-specimen species in papers with or without DNA data was 15.06% and 23.43%, respectively, which indicates that incorporating DNA data in species descriptions might effectively decrease the occurrence of single-specimen species. We suggest that taxonomists should adopt more beneficial practices, such as increasing specimen diversity, incorporating DNA data, and improving international collaboration, in the description of new species.

Publishing trends and productivity in insect taxonomy from 1946 through 2012 based on an analysis of the Zoological Record for four species-rich families

Insect taxonomy is fundamental to global biodiversity research, but few studies have been conducted to track progress in this field using objective criteria. This study reports publishing trends in the taxonomy of four diverse, globally-distributed insect families from 1946 to 2012 to elucidate recent progress and the current status of insect taxonomy. Publications included in the Zoological Record online literature database were analyzed for Cicadellidae (leafhoppers), Miridae (plant bugs), Pyralidae (moths) and Staphylinidae (rove beetles). Data on numbers of new species, article length, species description length, authorship and collaborations, and taxonomic journals were extracted and compiled for each year. The results showed that (1) the number of taxonomic papers increased before 1980, followed by a steep decline with subsequent partial recovery; (2) the number of papers describing new species generally mirrored the trend in numbers of new species, suggesting no overall change in the proportion of larger, synthetic works (monographs) and more such work is encouraged; (3) the average number of new species described per publication decreased over the time period investigated, but with an increase in the average description pages per new species; (4) researchers from Europe and North America continue to produce the most taxonomic research on three of the four families, but the main center for Cicadellidae taxonomy has recently shifted to Asia; (5) collaboration among authors within and across continents has increased as indicated by increases in coauthored papers; and (6) journal prevalence differed for the four families and the top 10 most utilized journals for each family were given out for reference. Based on the analysis of the publication trend of the four families, we found that the overall trend toward increasing rates of species discovery is encouraging. But more human resources training and financial support on taxonomic work are required in order to complete a global faunistic inventory in a reasonable timeframe. Future study that conducts more in-depth and comprehensive analysis based on more families is required to reflect the overall trend of the insect taxonomy.

Insect taxonomy, biodiversity research and the new taxonomic impediments

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