Abstract Species delimitation is critical to our understanding of evolution, biodiversity, and conservation. However, delimiting species boundaries can be challenging, especially when intraspecific divergence is high (and interspecific divergence is low), and gene flow and incomplete lineage sorting are present. Mygalomorph spiders have become models for examining a variety of evolutionary and biogeographical questions. However, their extreme morphological homogeneity and high genetic structuring make delimiting mygalomorph species especially challenging. Integrative approaches to species delimitation, which combine multiple lines of evidence, have been used to infer the limits of many mygalomorph groups in an independent and reproducible way. Yet molecular species delimitation and phylogenetic relationships of the purseweb spider family Atypidae remain scarce. In this study, we explored the phylogeny and species delimitation of Calommata spiders from southern China using data sets including three mitochondrial (COI, 16S, and 12S) and two nuclear (28S, H3) markers. Our phylogenetic analyses yielded a well‐supported clade containing all southern Chinese Calommata and a sister relationship between C. signata and three new species within it. Based on the single‐locus and multilocus species delimitation analyses, we delimited four Calommata species from southern China: one known species (C. signata) and three new species (C. yuanjiangica sp. n., C. hangzhica sp. n. and C. jinggangica sp. n.). This study thus provides a framework for determining the limits of C. signata sensu lato species and calls for further study of systematics and evolutionary relationships within Calommata and other atypid lineages.

Abstract Evolutionary analysis of Prodiamesinae has long been impeded by lack of information, and its phylogenetic relationship with Orthocladiinae remains questionable. Here, ten complete mitochondrial genomes (mitogenomes) of Orthocladiinae sensu lato were newly sequenced, including three Prodiamesinae species and seven Orthocladiinae species. Coupled with published mitogenomes, a total of 12 mitogenomes of Orthocladiinae sensu lato were selected for a comparative mitogenomic analysis and phylogenetic reconstruction. Mitogenomes of Orthocladiinae sensu lato are conserved in structure, and all genes arrange the same gene order as the ancestral insect mitogenome. Nucleotide composition is highly biased, and the control region displayed the highest A + T content. All protein‐coding genes are under purifying selection, and the ATP8 evolves at the fastest rate. In addition, the mitogenomes of Orthocladiinae sensu lato are highly conserved, and they are practically useful for phylogenetic inference, suggesting a re‐classification of Orthocladiinae by sinking Prodiamesinae as a subgroup of Orthocladiinae.

Abstract Many nominal species of microscopic animals traditionally fitting the ‘everything is everywhere’ paradigm have been revealed to be complexes of cryptic species. Here, we explore species diversity within the micrometazoan flatworm Gyratrix hermaphroditus—unique among meiofauna because of its global occurrence in a wide variety of brackish, freshwater and marine environments. With maximum likelihood and Bayesian approaches, we analysed 18S, 28S, 5.8S and ITS2 rDNA sequences from 401 specimens across the global distribution of G. hermaphroditus. Generalized Mixed Yule Coalescent (GMYC) and Automatic Barcode Gap Discovery (ABGD) methods delineated 78 and 62 putative species, respectively. This renders G. hermaphroditus one of the most species‐rich complexes known to date. Based on shape variations of the male copulatory organ, 14 morphotypes corresponding with molecular clades were identified within the species complex. Within morphotypes, morphometric measurements were able to further discriminate between GMYC species using discriminant analyses. While most putative species occur on local or regional scales, over 10% are distributed over vast distances (>500 km apart) and two GMYC and six ABGD species have colonised multiple continents. This suggests that the cosmopolitanism of the G. hermaphroditus species complex is not just caused by mixing cryptic species with a more limited geographic distribution, but is due to the presence of previously unrecognised cosmopolitan taxa. The wide variation in distribution patterns between putative species indicates that meiofaunal biogeography should not be simplified into ‘everything is everywhere’, but rather entails every ecological state, extending from local endemism to true cosmopolitanism.

Abstract The Atya genus classification is mostly stabilized, comprising 13 species in the Americas and West Africa. However, nearly 40 years have passed since its last revision. Some taxonomic questions remained due to morphological uncertainty, and new ones have been raised with molecular Atyidae phylogenies. The aim of this study was to conduct the first Atya molecular systematic assessment, verifying the taxonomic status of A. gabonensis, A. innocous, A. margaritacea and A. scabra. Gene fragments (16S, COI and H3) were obtained by DNA sequencing and used for genetic distance, phylogeny and species delimitation analyses (ABGD, PTP and GMYC). Our data corroborate A. gabonensis as a species with amphi‐Atlantic distribution and suggest the use of A. innocous for specimens of the Caribbean Sea. We revalidated A. tenella Smith, 1871 for specimens from Pacific. Atya margaritacea, distributed along the Pacific coast of the Americas, was considered a valid and distinct species from A. scabra, which is distributed in the Atlantic and Pacific coasts of the Americas and West Africa; moreover, maybe this wide distribution belongs to a distinct species, being A. scabra restricted to "Gulf of Mexico lineage". We corroborated the genus as monophyletic and highlighted remaining systematic issues. Overall, our multigene‐based phylogeny and species delimitation analyses suggest that Atya comprises 14 species. This study provides data for future studies on the biodiversity, evolution and conservation of freshwater Atyidae shrimps and Neotropical fauna.

Abstract The pan‐Antarctic distributions of several collembolan species have been supported by morphology for over 120 years. However, for most species where molecular data are available, these are now known to belong instead to several species, and most classified as short‐range endemics. One such species, Friesea grisea, had a pan‐Antarctic distribution that has been in question, but until recently, specimens of F. grisea from the type locality on South Georgia have not been included in any molecular appraisal. Here, we compare the molecular identity of specimens of F. grisea, from South Georgia, with other Antarctic and sub‐Antarctic species using the mitochondrial COI gene. A Bayesian phylogenetic analysis for 14 species of Friesea from southern regions, including F. grisea sensu stricto with species previously identified as ‘F. grisea’ (F. antarctica, F. gretae and F. propria) confirms the distinctness of the South Georgian specimens based on molecular data, and these results are confirmed morphologically. The genus Friesea is one of the most speciose genera of Collembola known in the Antarctic region, and we provide an annotated key (dichotomous and interactive versions) to all Friesea species in the sub‐Antarctic and Antarctica. We compare the biogeography of Friesea to other Collembola from the region to highlight our current understanding of species boundaries and island linkages.

Abstract Pacific island land snails exhibit exceptionally high species diversity, morphological diversity, and endemism. Species within superfamily Punctoidea, which contains the Charopidae and Pacific‐endemic family Endodontidae, are among the most morphologically spectacular Pacific endemic land snails. The evolution of Pacific island punctoids remains poorly known, due in part to rampant human‐induced extinction within this group of minute ground‐dwellers. The Belau archipelago (Republic of Palau) with its relatively intact lowland rainforest and limestone karst Rock Islands, is home to many endemic punctoids and presents a unique opportunity to better understand the diversification of one of the most diverse but also imperiled land snail lineages on Pacific islands. For the first time, the diversification of the endemic Pacific punctoid fauna of Belau was studied using Bayesian Inference (BI) and Maximum Likelihood (ML) methods applied to sequences from mitochondrial (COI) and nuclear (ITS2) gene regions. Evolutionary relationships, molecular divergence, disjunct or complex geographic ranges, and ecological similarity among Belau punctoid species, likely reflect species’ long evolutionary history and diversification through geographic isolation. We find no evidence for adaptation in species‐level shifts in spire height within Aaadonta endodontids. We also find preliminary evidence for the evolution of premating reproductive isolation in Semperdon species in sympatry, through the study of apertural teeth. In addition, we report the first new endodontid species from living individuals as well the first new genus record from the Belau archipelago in nearly half a century.

Abstract The leaf‐eared mouse, Phyllotis xanthopygus (Waterhouse 1837) is a widely distributed sigmodontine rodent in South America, with populations ranging from central Peru to southern Argentina and Chile. Previous morphological and molecular contributions have suggested that P. xanthopygus represents a species complex. In order to characterize and disclose this cryptic species complex, we perform a molecular genetic/phylogenetic analysis of representative samples across its geographical distribution. Phylogenetic analyses were based on sequences of cytochrome‐b gene (801 base pairs; n = 114 specimens) and analysed by maximum likelihood and Bayesian approaches. We also employed a Bayesian implementation of the Poisson tree processes (bPTP) as a unilocus species delimitation method. Results from our phylogenetic analyses retrieve eight well‐supported clades. Five of these clades belong to populations known as P. xanthopygus s.l., which were paraphyletic to the closely related species P. bonariensis, P. caprinus, and P. limatus, displaying strong genetic divergences (>8%). The (bPTP) analyses recovered ten species within P. xanthopygus s.l. plus related forms (i.e. P. bonariensis, P. caprinus, and P. limatus). Our results, coupled with chromosomal and morphological evidences, support the recognition of these clades at the species level and provide a new framework to characterize the leaf‐eared mice complex. Our study highlights the importance of integrative approaches in disentangling the biodiversity of Neotropical rodents.

Abstract The study of phenotypic evolution in island birds following colonization is a classic topic in island biogeography. However, few studies explicitly test for the role of selection in shaping trait evolution in these taxa. Here, we studied the Azores woodpigeon (Columba palumbus azorica) to investigate differences between island and mainland populations, between females and males, and interactions between geographical origin and sex, by using spectrophotometry to quantify plumage colour and linear measurements to examine external and skeletal morphology. We further tested if selection explains the observed patterns by comparing phenotypic differentiation to genome‐wide neutral differentiation. Our findings are consistent with several predictions of morphological evolution in island birds, namely differences in bill, flight and leg morphology and coloration differences between island and mainland birds. Interestingly, some plumage and morphological traits that differ between females and males respond differently according to geographical origin. Sexual dimorphism in colour saturation is more pronounced in the mainland, but this is driven by selection on female plumage coloration. Differences in flight morphology between females and males are also more pronounced in the mainland, possibly to accommodate contrasting pressures between migration and flight displays. Overall, our results suggest that phenotypic differentiation between mainland and island populations leading to divergent sexual dimorphism patterns can arise from selection acting on both females and males on traits that are likely under the influence of natural and sexual selection.

Abstract Crambidae is a group of moths with more than 10,000 species occurring worldwide that evolved diverse morphological and ecological habits. They can be best recognized by morphological characters of the adult tympanal organ and larval chaetotaxy. We present the first molecular phylogeny of Crambidae including all subfamilies and most tribes. We use available molecular data from two previous studies, and published transcriptomes and genomes, compiling ten genes totalling 11,247 bp. Up to eight genes are sequenced for thirty‐nine additional taxa, with Cathariinae, Cybalomiinae and Linostinae sampled for the first time. Maximum‐likelihood and Bayesian analyses recover topologies mostly agreeing with those of previous studies, with several groupings showing better support. Cathariinaesyn. n.and Cybalomiinaesyn. n.are recovered as ingroup of Glaphyriinae and are consequently synonymized with the latter. Linostinae are either sister to Glaphyriinae or sister to the ‘CAMMSS clade’. Lathrotelinae are recovered monophyletic and as sister to Musotiminae in the Bayesian analysis. Hoploscopinaestat. n.are recovered as sister to ((Crambinae + Erupinaestat. n.) + (Scopariinae + Heliothelinae s. str.)). Evolution of host‐plant preferences is discussed.