RESUMO
BACKGROUND: Phylogenetic relationships among the myriapod subgroups Chilopoda, Diplopoda, Symphyla and Pauropoda are still not robustly resolved. The first phylogenomic study covering all subgroups resolved phylogenetic relationships congruently to morphological evidence but is in conflict with most previously published phylogenetic trees based on diverse molecular data. Outgroup choice and long-branch attraction effects were stated as possible explanations for these incongruencies. In this study, we addressed these issues by extending the myriapod and outgroup taxon sampling using transcriptome data. RESULTS: We generated new transcriptome data of 42 panarthropod species, including all four myriapod subgroups and additional outgroup taxa. Our taxon sampling was complemented by published transcriptome and genome data resulting in a supermatrix covering 59 species. We compiled two data sets, the first with a full coverage of genes per species (292 single-copy protein-coding genes), the second with a less stringent coverage (988 genes). We inferred phylogenetic relationships among myriapods using different data types, tree inference, and quartet computation approaches. Our results unambiguously support monophyletic Mandibulata and Myriapoda. Our analyses clearly showed that there is strong signal for a single unrooted topology, but a sensitivity of the position of the internal root on the choice of outgroups. However, we observe strong evidence for a clade Pauropoda+Symphyla, as well as for a clade Chilopoda+Diplopoda. CONCLUSIONS: Our best quartet topology is incongruent with current morphological phylogenies which were supported in another phylogenomic study. AU tests and quartet mapping reject the quartet topology congruent to trees inferred with morphological characters. Moreover, quartet mapping shows that confounding signal present in the data set is sufficient to explain the weak signal for the quartet topology derived from morphological characters. Although outgroup choice affects results, our study could narrow possible trees to derivatives of a single quartet topology. For highly disputed relationships, we propose to apply a series of tests (AU and quartet mapping), since results of such tests allow to narrow down possible relationships and to rule out confounding signal.
Assuntos
Artrópodes , Filogenia , Animais , Artrópodes/classificação , Artrópodes/genética , TranscriptomaRESUMO
The Austrian endemic land snail species Noricella oreinos (formerly Trochulus oreinos) occurs in the Northeastern Calcareous Alps at high elevations. Two morphologically highly similar subspecies N. o. oreinos and N. o. scheerpeltzi have been described. First analyses of mitochondrial and nuclear marker sequences indicated a high genetic divergence between them. In the present study, we aimed to assess gene flow between the two subspecies which should help to re-evaluate their taxonomic status. Sequence data and amplified fragment length polymorphism (AFLP) markers of 255 Noricella specimens covering the whole distribution range were analyzed. A clear geographic separation was found within the potential contact zone, the Haller Mauern mountain range. Samples of all western sites were part of the clade representing N. o. scheerpeltzi and almost all samples from the eastern sites clustered with N. o. oreinos. However, within two sampling sites of the eastern Haller Mauern, a few individuals possessed a COI sequence matching the N. o. oreinos clade whereas at the ITS2 locus they were heterozygous possessing the alleles of both taxa. Contrary to the ITS2 results indicating historical and/or ongoing hybridization, AFLP analyses of 202 individuals confirmed a clear separation of the two taxa congruent with the mitochondrial data. Although they occur on the same mountain range without any physical barrier, no indication of ongoing gene flow between the two taxa was found. Thus, we conclude that the two taxa are separate species N. oreinos and N. scheerpeltzi.
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The taxonomy of the family Paracortinidae Wang & Zhang, 1993 is revised based on literature, old and recently collected material. A new genus Crassipetalum Akkari & Stoev, gen. nov. is described, to accommodate a new species Crassipetalummagnum Akkari & Stoev, gen. nov. et sp. nov. and a recently described species Crassipetaluminflatum (Chen, Zheng & Jian, 2023), comb. nov. The genus Scotopetalum Shear, 2000 hitherto described for the Vietnamese species S.warreni Shear, 2000 and subsequently synonymised with the genus Paracortina Wang & Zhang, 1993 is here resurrected and supplemented with another species, S.chinensis (Stoev & Geoffroy, 2004), comb. nov., ex Paracortinachinensis Stoev & Geoffroy, 2004. The status of the fourth genus in the family, Angulifemur Zhang, 1997, is reconfirmed. Based on recently collected specimens from China, two new species of the genus Paracortina are described: P.asciformis Akkari & Stoev, sp. nov. (Sichuan Prov., Lixian County) and P.kabaki Akkari & Stoev, sp. nov. (Yunnan, Shangrila County). The Vietnamese species Paracortinamultisegmentata Stoev & Geoffroy, 2004 and Paracortinakyrang Nguyen, Stoev, Nguyen & Vu, 2023 are considered of uncertain taxonomic position within Paracortinidae. Differential diagnoses for the proposed genera as well as for all the species are presented, and descriptions or descriptive notes for all the species are provided, using a standardised terminology, and when possible, accompanied by micrographs of the habitus and gonopod structures. An identification key based on gonopod structures is proposed for all the members of the family. A discussion on species affinities, secondary sexual characters, troglomorphic characters, geographical distribution, and habitat preferences are also provided together with a distribution map for all members of the family.
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The glomerid genus Trachysphaera Heller, 1858 in Serbia is revised, based on recently collected specimens and historical material. Six species are presently recorded from Serbia, viz., Trachysphaera corcyraea (Verhoeff, 1900), T. cristangula (Attems, 1943), T. schmidtii Heller, 1858, and T. similicostata (Radu Ceuca, 1951), all new to the fauna of the country, as well as T. costata (Waga, 1857a) and T. lobotarsus (Attems, 1943). All of these species are richly illustrated and mapped. To verify the identity of some species, historical material from the Natural History Museum in Vienna, including syntypes, is also studied, and two lectotypes have been designated. Some misidentifications from the literature have been corrected. Trachysphaera acutula (Latzel, 1884) syn. n., T. cultrifera (Verhoeff, 1906) syn. n. and T. multiclavigera (Verhoeff, 1898) syn. n. are all considered as junior subjective synonyms of T. schmidtii. Trachysphaera attemsi Golovatch, 1976 syn. n. is transferred from the list of synonyms of T. costata to the list of synonyms of T. corcyraea. One species, T. similicostata, is resurrected from synonymy. Relationships between some congeners and the taxonomic problems within the genus are briefly discussed.