Stilbonematinae are a subfamily of conspicuous marine nematodes, distinguished by a coat of sulphur‐oxidizing bacterial ectosymbionts on their cuticle. As most nematodes, the worm hosts have a relatively simple anatomy and few taxonomically informative characters, and this has resulted in numerous taxonomic reassignments and synonymizations. Recent studies using a combination of morphological and molecular traits have helped to improve the taxonomy of Stilbonematinae but also raised questions on the validity of several genera. Here, we describe a new circumtropically distributed genus Paralaxus (Stilbonematinae) with three species: Paralaxus cocos sp. nov., P. bermudensis sp. nov. and P. columbae sp. nov. We used single worm metagenomes to generate host 18S rRNA and cytochrome c oxidase I (COI) as well as symbiont 16S rRNA gene sequences. Intriguingly, COI alignments and primer matching analyses suggest that the COI is not suitable for PCR‐based barcoding approaches in Stilbonematinae as the genera have a highly diverse base composition and no conserved primer sites. The phylogenetic analyses of all three gene sets, however, confirm the morphological assignments and support the erection of the new genus Paralaxus as well as corroborate the status of the other stilbonematine genera. Paralaxus most closely resembles the stilbonematine genus Laxus in overlapping sets of diagnostic features but can be distinguished from Laxus by the morphology of the genus‐specific symbiont coat. Our re‐analyses of key parameters of the symbiont coat morphology as character for all Stilbonematinae genera show that with amended descriptions, including the coat, highly reliable genus assignments can be obtained.

Abstract Spiders of the genus Micaria are ground‐living mimics of ants. Species delineation in these spiders is challenging, mainly because of exceptional high levels of intraspecific variation masking species boundaries. As implied by preliminary DNA barcode data from Central Europe, the Holarctic and very widely distributed glossy ant‐spider M. pulicaria shows cryptic diversity. Here, we disentangle the hidden diversity by means of an integrative taxonomy approach, using mitochondrial DNA, morphometrics, traditional genitalic characters and ecology. Our data suggest the clear delineation of two distinct species, which supports the conception of 19th century taxonomists. These early naturalists distinguished M. pulicaria and a second closely related species based on morphology and natural history, which were synonymized in subsequent taxonomic studies. Therefore, we re‐circumscribe M. pulicaria and revalidate the long forgotten M. micans. These two Micaria species co‐occur sympatrically in vast areas of the western Palearctic, while the Nearctic region is populated by M. pulicaria alone. Male genitalic traits are more dissimilar in the area of sympatry than in allopatry, suggesting a decisive role of reproductive character displacement in species diversification. Our study emphasizes the value of the early taxonomic literature in integrative taxonomic studies, as it may contain crucial information on natural history that are not regularly recorded by modern taxonomists.

Abstract The latest progress of the taxonomy is the use of integrative approach for species delimitation based on a multisource dataset. However, the taxonomic decision that should be made when convergence between the different lines of evidence is not observed remains debated. Here, we investigate the consequences of the application of an ‘integration by cumulation’ approach on the taxonomic statuses within the Bombus lapidarius complex when using an integrative taxonomic framework (i.e. nuclear and mitochondrial markers along with reproductive traits) compared with a strict ‘integration by congruence’ method. Our results show similar taxonomic conclusions whatever the decision‐making approach used except for one taxon. According to the differentiation observed in our integrative taxonomic framework, recent divergence time and other field observations for this taxon, we assume that a too strict decision‐making method could fail to detect recently diverged species. This is exemplified by the new species Bombus bisiculus sp. n. occurring in South Italy and Sicily.

Abstract Previous studies have indicated the occurrence of nine species of Palaemon in Brazil. However, the extensive variability in their diagnostic characters and the geographic distribution of some species raises doubts about the validity of some taxa, potentially indicating the occurrence of species not yet reported from Brazil or even not described. To solve taxonomic issues with Palaemon species in Brazil, we carried out a multigene analysis by using partial fragments of 16S and COI mitochondrial genes and the nuclear H3. Phylogenetic relationships were inferred by maximum likelihood and Bayesian inference. The external morphology corresponding to the terminal clades obtained in the molecular phylogram was analysed to identify diagnostic characters that allow the recognition of the groups and the correct taxa assignment. The combined analysis of molecular and morphological data confirms the existence of nine species of Palaemon in Brazil, five from the “Palaemon” lineage (P. mercedae and four Palaemon stensu stricto—P. argentinus, P. octaviae—first record in Brazil, P. northropi and P. paivai) and four of the “Alaocaris” lineage (P. carteri, P. ivonicus, P. pandaliformis and P. yuna). The possibility of further cryptic speciation is also pointed out. In addition to confirming the validity of the nine species, the results indicate the need for taxonomic adjustments and corresponding changes in the geographic distribution of Palaemon species occurring in Brazil.

Abstract The Masoninae (type genus Masona van Achterberg) is a widespread but seldom collected group of morphologically aberrant tiny (body length 2 mm or less) wasps that have always been considered as a subfamily of Braconidae, albeit on little supporting evidence. Discovery of a fully winged female of Masona from remote Australia has enabled a reassessment of its relationships. This specimen yielded sequence data for the nuclear 28S and 18S rDNA genes, the barcoding fragment of mitochondrial cytochrome oxidase subunit 1 and the mitochondrial 16S rDNA gene. These were analysed separately and together, along with representatives of Braconidae and Ichneumonidae. Maximum likelihood analyses of all four genes separately and combined concur that Masona is nested within the Ichneumonidae and, therefore, is not a member of Braconidae. This is also supported by the position of the sternaulus low on mesopleuron, absence of fore wing vein (RS + M)a (though the great reduction in wing venation makes further interpretation problematic) and the articulated junction of metasomal tergites 2 and 3. On balance, molecular analyses place Masona basally among the ophioniformes lineage of Ichneumonidae. Formal description of the Australian species as Masona timpaynei Quicke sp. n. and a revised diagnosis of Masoninae are provided in S1 together with illustration of the holotype.

Abstract The 24 members of the Euro‐Asiatic genusThymogethesare highly specialized pollen beetles associated as larvae with flowers of Lamiaceae Nepetoideae. All members of the genus were analysed in within the framework of an integrative taxonomy approach, which was aimed to reconstruct the phylogenetic relationships, as well as the possible pattern of evolution of their larval‐host‐plant association. Evidence from multiple molecular markers [COI; 16S; H3], combined with an estimation of divergence times using an average rate of 0.0177 substitutions/site/My among branches, placed the origin of the genus at a minimum of 9–10 Mya. This date of origin approximates the known evolution of the host plants in Euro‐Mediterranean areas. Evidence from combined molecular and cladistic morphological analyses resulted in suitable agreement with the previously established morphology‐based systematics of the genus, although members of theexilisspecies‐group were split into three clades. The only disagreement between results of this new combined phylogeny and previous classification is in the exclusion of “Thymogethes”grenieri. This species is herein positioned outside the genus, based on molecular evidence. Our analysis depicts severalThymogethesspecies differentiating in the last few Mys, specifically those included in theT. lugubrisspecies‐group. Combined evidence from DNA, morphology and ancestral state parsimony reconstruction of larval‐host‐plant associations suggests that subtribe Menthinae likely represents the ancestral host plants, with a series of independent host shifts during the radiation of the clade, in association first with Menthinae and subsequently with Lavandulinae and Nepetinae. Steno‐oligophagy is the most frequent (86%) condition, while strictly monophagous species are less numerous (14%).

Abstract Similar morphological characters and little molecular data ofAmphioctopus rex,A. neglectusandA. cf. ovulumresulted in their unknown phylogenetic statuses and equivocal relationships. In this study, the complete mitochondrial genomes of these three species collected in Chinese waters were sequenced and compared with each other to clarify the relationships among them. The lengths of the mitochondrial genomes varied from 15,646 bp to 15,814 bp, and the A + T content and GC skew for protein‐coding genes showed little variation. In contrast, both a dendrogram based on codon usage and the gene arrangements of the three octopuses showed thatA. rexwas more closely related toA. neglectusthan toA. cf. ovulum. Five data sets and two methods (maximum likelihood and Bayesian inference) were utilized for the first time to explore the phylogenetic relationships among these three species in Octopodidae. The results indicated that a data set combining protein‐coding genes and RNA genes (PR) was optimal for analysing the relationships among 43 cephalopods. All of the phylogenetic trees divided the cephalopods into 10 taxa and supported the monophyly of Oegopsida, Myopsida, Sepiidae and Octopodidae. In this study, Idiosepiidae was classified as sister to Sepiolidae. Trees constructed using all data sets robustly supported the monophyly of the genusAmphioctopus. Notably,A. rexwas more closely related toA. neglectusthan toA. cf. ovulum, although these three species share the characteristic of violet rings on dark ocelli.

Abstract Hydrozoans of the genus Zanclea have been acknowledged only recently as a fundamental component of the highly diverse fauna associated with reef‐building scleractinian corals. Although widely distributed in coral reefs and demonstrated to be important in protecting corals from predation and diseases, the biodiversity of these hydrozoans remains enigmatic due to the paucity of available morphological characters, incomplete morphological characterisations and the possible existence of cryptic species. Recently, molecular techniques have revealed the existence of multiple hidden genetic lineages not yet supported by diagnostic morphological characters. In this work, we further explore the morpho‐diversity of three genetic lineages, namely Zanclea associated with the coral genera Goniastrea (clade I), Porites (clade II) and Pavona (clade VI). Aside from providing a complete classical characterisation of the polyp and medusa stage of each clade, we searched for new potential taxonomic indicators either on symbiotic hydroids or on host corals. On the hydroids, statistical analyses on almost 7,000 nematocyst capsules revealed a significant difference in terms of nematocyst size among the three Zanclea clades investigated. On each host coral genus, we identified peculiar skeletal modifications related to the presence of Zanclea symbionts. Lastly, we discussed the potential diagnostic value of these footprints in the characterisation of Zanclea–scleractinian associations.

Abstract Freshwater mussels (Bivalvia, Unionidae) have suffered strong declines over the last century. High morphological plasticity of Unionidae causes disturbances in their systematics and taxonomy, hampering conservation efforts. Species that have historically been placed under the North American genus Quadrula have suffered from numerous taxonomic and species delineation problems since its inception. Four genera are presently recognized within Quadrula sensu lato, that is, Cyclonaias, Quadrula, Theliderma and Tritogonia, but their phylogenetic basis remains incompletely tested. In the present study, we reconstructed several two‐marker (mtDNA cytochrome c oxidase subunit I—COI and NADH dehydrogenase subunit 1—ND1) phylogenies with newly collected specimens and all previously available sequences covering most species within this group. We then delineated the species within the group using an integrative approach with the application of molecular statistical methods, morphometric (Fourier Shape) analyses and geographic distribution data. Four clades corresponding to these genera were consistently recovered in all phylogenies. To validate the generic status of these clades, molecular analyses were complemented with morphological, anatomical and ecological data compiled from the literature. Several revisions are here proposed to the current systematics and taxonomy of these genera, including the synonymization of Cyclonaias asperata under Cyclonaias kieneriana; the inclusion of Quadrula apiculata and Quadrula rumphiana under Quadrula quadrula; the placement of Quadrula nobilis under Tritogonia; and finally the separation of the Mobile River basin populations of Theliderma metanevra as a new species, that is, Theliderma johnsoni n. sp. The conservation implications of the proposed changes are then discussed.