ABSTRACT Abyssal environments (3000–6000 m ocean depth) are often presumed to promote broad genetic connectivity across ocean basins due to their vast spatial extent, apparent environmental homogeneity and few barriers to gene flow. While some deep‐sea taxa conform to this expectation, growing evidence shows that marked genetic structure can persist even in widely distributed species. Here, we reassess lineage structure within two widespread abyssal amphipods, Paralicella tenuipes Chevreux, 1908 and Paralicella caperesca Schulenberger & Barnard, 1976, using multilocus data (COI, 16S rRNA, 28S rRNA) from expanded global abyssal sampling. Species delimitation analyses recovered recurrent mitochondrial lineage structure within P. tenuipes and stronger multilocus divergence within P. caperesca , consistent with interpretation of the latter as a species complex. TCS haplotype networks showed no consistent geographic or depth‐associated separation, with recovered lineages and major haplotypes distributed across multiple ocean basins. Demographic and neutrality tests indicated moderate to high mitochondrial diversity in P. tenuipes but no consistent species‐wide signal of recent demographic change, whereas P. caperesca showed higher mitochondrial diversity and stronger, marker‐dependent demographic signals. Together, these results indicate genetic structure that is not strongly associated with geography or depth. The geographic extent of sampling demonstrates that Paralicella ranks among the most widely distributed deep‐sea amphipod genera to date. This combination of broad abyssal distribution and non‐geographically associated lineage structure indicates that the processes generating genetic diversity in these amphipods do not align neatly with the geographic units commonly used to infer diversification in abyssal ecosystems.
ABSTRACT Cephalaspidea is a key group within the Heterobranchia characterized by high species diversity and broad ecological disparity, and it is widely studied in marine ecology and systematics. Previous studies have proposed a preliminary phylogenetic framework for Cephalaspidea using few sanger sequenced phylogenetic markers and transcriptome‐scale datasets. However, relationships among several lineages remain contentious, which may partly reflect sparse sampling of key taxa and differences in topological signal among markers, datasets and analytical assumptions. To clarify the phylogenetic backbone of Cephalaspidea, newly generated shallow‐genome data from 13 species are integrated with published mitochondrial genomes and transcriptomes. Relationships within Cephalaspidea are reconstructed and compared across multiple inference frameworks. Both mitochondrial gene matrices and phylogenomic multilocus matrices are analysed. Across datasets and analytical strategies, strong support for Cephalaspidea monophyly is consistently recovered. Several major backbone relationships are also recovered consistently. Newnesioidea is placed at the base of the Cephalaspidea tree. Philinoidea is recovered as sister to the clade comprising all Bulloidea, Cylichnoidea and Haminoeoidea. However, within the Bulloidea–Cylichnoidea–Haminoeoidea clade, topological differences are observed across data types and inference frameworks. Bullidae and Tornatinidae are not recovered as sister lineages in any analysis, leaving the monophyly of the traditional Bulloidea unsupported under the current taxon sampling. Tornatinidae is placed near Cylichnidae in phylogenomic analyses, suggesting a relationship that warrants further testing. By contrast, Mnestiidae does not cluster with Cylichnidae but is instead recovered closer to Haminoeoidea, which warrants further scrutiny of the circumscription of Cylichnoidea. Overall, a broadly consistent backbone topology is recovered through expanded taxon sampling of key lineages. New molecular evidence and analytical frameworks are provided to further test unresolved phylogenetic relationships, thereby refining our understanding of Cephalaspidea phylogeny.
ABSTRACT Heterochrony, defined as evolutionary changes in developmental timing, is a key mechanism underlying morphological diversification across taxa. Although several quantitative approaches have been developed to detect heterochronic patterns using geometric morphometric data, most are limited to pairwise comparisons among extant species and do not explicitly incorporate phylogenetic structure. Here, we present a phylogenetic extension of the peramorphosis test that enables the inference of heterochronic changes among ancestor–descendant pairs across an entire phylogeny, with ancestral shapes reconstructed by using maximum‐likelihood estimation under a Brownian‐motion model of trait evolution. This extension was implemented in an R script ( phylo.peram.test.R ) available online. The approach combines Procrustes regression to estimate ontogenetic trajectories, prediction of species‐specific offset shapes, and reconstruction of ancestral morphologies. Heterochronic events are inferred by comparing multivariate distances from an archetypic juvenile shape to ancestral and descendant shapes for a given tree branch. To evaluate the robustness of the patterns inferred, the approach implements a bootstrap resampling procedure that propagates within‐species variation through all analytical steps and records the recovery frequencies for each inferred event. We illustrate the method using two published datasets of cranial and head shape in mammals and pythons, respectively. Results are largely congruent with those obtained using PASOS, an alternative phylogenetic approach for testing heterochrony, although some discrepancies arise from differences in the reconstruction of ancestral states and in the criteria used by each method to identify heterochronic changes. Overall, the phylogenetic peramorphosis test provides a robust framework for detecting heterochronic patterns in a comparative context.
ABSTRACT This study presents the first phylogeny of the genus Minettia Robineau‐Desvoidy, reconstructed from five gene markers ( COI , Cytb , 16S , 18S and 28S ) and incorporating representatives of all five recognized subgenera. Analyses of 56 species (49 Minettia spp.+seven outgroups) support the monophyly of Minettia , but the monophyly of the subgenera Frendelia , Minettia , Minettiella and Plesiominettia is not supported; the monophyly of the subgenus Scotominettia cannot be tested as only one species was sampled. A close relationship between Minettiella and Plesiominettia was strongly supported, corroborated by the presence of facial tubercle morphology as a potential synapomorphy. The taxonomically problematic Minettia baihualingensis had an unstable phylogenetic position, consistent with its morphological intermediacy and inability to be assigned to any existing subgenus. Ancestral state reconstruction demonstrates that key diagnostic traits, such as the coloration of the wing base, arista morphology and the absence of the dorsal phallic sclerite, are highly homoplastic, having evolved independently multiple times. The first Chinese record of the subgenus Scotominettia ( M. ( Scotominettia ) austriaca ) is also reported. Overall, our results provide a phylogenetic framework that fundamentally challenges the current morphology‐based subgeneric classification and highlights the need for its integrative revision.
ABSTRACT The hypothesis of a Gondwanian origin of the family Tingidae (Insecta, Heteroptera) has been promoted and seems to be generally accepted by specialists. However, the area of emergence and diversification of the clade, South American or Australian, is still debated and cannot be solved without integrating Vianaidinae, a subfamily considered as the sister of all the other Tingidae, into phylogenetic and biogeographic analyses. This study aims to propose a molecular phylogeny integrating the three known Tingidae subfamilies for the first time, to date the emergence of the great clades using fossil calibrations and to test the origin of Tingidae. We tested the effect of different a priori parameters and sets of fossil calibrations. The uniform probability distribution gives older ages of the emergence of the main clades than the exponential and lognormal probability distributions. The emergence dates of the main clades differ slightly according to the number of calibrations with the exponential probability distribution, but significantly with the uniform probability distribution. We tested the hypothesis of the Gondwanian origin of Tingidae using DEC and DIVALIKE analysis. Tingidae may originate between the Neotropical and Afrotropical regions and spread out in Eastern and Northern regions mainly by long distance dispersal.
