New light into the hormogastrid riddle: morphological and molecular description of Hormogaster joseantonioi sp. n. (Annelida, Clitellata, Hormogastridae)

Molecular analysis of five controversial Balkanic species of Allolobophora (sensu lato) Eisen, 1873 (Lumbricidae, Clitellata) with emendation of the genus Cernosvitovia Omodeo, 1956

Allolobophora (sensu lato) is one of the most controversial genera in the taxonomy of Lumbricidae. Due to its poor definition, this genus is plagued by extensive taxonomic confusion, and its generic composition and internal relationships have remained uncertain, especially in species of the Balkan Peninsula. In this study, we have combined the study of morphological data and molecular phylogenetics based on five genetic markers, regions of the nuclear 28S rRNA and mitochondrial 16S rRNA, 12S rRNA, NADH dehydrogenase (ND1) and cytochrome oxidase C subunit 1 (COI), to delimit the taxonomic status of five controversial Balkanic endemic species, Allolobophora (s.l.) dofleini, Allolobophora (s.l.) serbica, Allolobophora (s.l.) strumicae, Allolobophora (s.l.) paratuleskovi and Allolobophora (s.l.) treskavicensis, sampled in the Kopaonik Mountain. Phylogenetic analyses based on our sampling of these five species recovered a well-supported clade containing the species Allolobophora (s.l.) robusta, Allolobophora (s.l.) mehadiensis mehadiensis, Allolobophora (s.l.) sturanyi dacica, Cernosvitovia rebeli and Cernosvitovia dudichi. Based on these results and previous evidence, the aforementioned Balkanic species are transferred to a redefined Cernosvitovia. We further present a revised list of all species currently included in Cernosvitovia., which includes now 21 species and subspecies taxa, 13 of them newly combined here. Serbiona Mršić & Šapkarev, 1988 is considered a junior synonym of Cernosvitovia Omodeo, 1956.  

Sokefun, Yadav S. Disentangling earthworm taxonomic stumbling blocks using molecular markers

Taxonomic classification of earthworms based on anatomical features has created several challenges for systematics and population genetics. This study examines the application of molecular markers, in particular mitochondrial cytochrome oxidase (COI), to facilitate discrimination of closely related earthworm species. Molecular markers have also provided insights into population genetics by aiding assessment of genetic diversity, lineage sorting, and genealogical distributions of populations for several species. Phylogeography—a study that evaluates the geographical distribution of these genealogical lineages and the role of historical processes in shaping their distribution—has also provided insights into ecology and biodiversity. Such studies are also essential to understand the distribution patterns of invasive earthworm species that have been introduced in non-native ecosystems globally. The negative consequences of these invasions on native species include competition for food resources and altered ecosystems. We anticipate that molecular markers such as COI and DNA barcoding offer potential solutions to disentangling taxonomic impediments in earthworms and advancing their systematics and population genetics. 

Cryptic Clitellata: Molecular Species Delimitation of Clitellate Worms (Annelida): An Overview

Methods for species delimitation using molecular data have developed greatly and have become a staple in systematic studies of clitellate worms. Here we give a historical overview of the data and methods used to delimit clitellates from the mid-1970s to today. We also discuss the taxonomical treatment of the cryptic species, including the recommendation that cryptic species, as far as possible, should be described and named. Finally, we discuss the prospects and further development of the field.

Integrative systematic revision of a Mediterranean earthworm family: Hormogastridae (Annelida, Oligochaeta)

The problem of reconciling earthworm taxonomy and phylogeny has shown advances with the application of molecular techniques, yet they have proven insufficient. Integrative systematics could solve this by combining multiple sources of evolutionary information. Relatively low diversity, restricted range and low nomenclatural conflict make Hormogastridae Michaelsen, 1900 a desirable target for an integrative systematics approach. The main systematic conflicts within this family are the polyphyly of the species Hormogaster pretiosa Michaelsen, 1899, the widespread presence of cryptic lineages, the lack of resolution of supraspecific relationships and the paraphyly of the genus Hormogaster Rosa, 1877 (found to be composed of four well-supported genus-level clades by molecular phylogenetic inference). This work integrates all the existing information by performing phylogenetic inference based on morphological, molecular and total evidence datasets, comparing their performance with the topology obtained by phylogenomic analyses. It also includes a comparative study of representatives of the main clades based on microcomputed tomography (µCT) reconstructions. The addition of morphological characters improved the resolution of the Hormogastridae tree; ancestral state reconstruction displayed the evolution of character states and provided morphological diagnoses for the genera within a new system, which incorporates information about ecological niches and biogeography.

Integrated taxonomy reveals multiple species in the Dendrobaena byblica (Rosa, 1893) complex (Oligochaeta: Lumbricidae)

Dendrobaena byblica (Rosa, 1893) is a Circum-Mediterranean species complex composed of at least 17 nominal taxa. Regarding the most important species characters (clitellum and tubercles) the worms belonging to the genus Fitzingeria Zicsi, 1978 seem to be very close to the D. byblica species group. Here we provide the first molecular phylogenetic analysis of the byblica species group and the Fitzingeria species, and show that the genus Fitzingeria is polyphyletic and groups together with the Carpathian and Balkanic deeply pigmented byblica forms. The other main clade consists of the ‘classical’ byblica species. The morphological characteristics also support these results. On the basis of the molecular and morphological characters the species of the former Fitzingeria were relegated to Dendrobaena and four new species were described together with a new replacement name Dendrobaena carpathomontana nom. nov. for F. platyura montana (Černosvitov, 1932).

Pinpointing cryptic borders: Fine-scale phylogeography and genetic landscape analysis of the Hormogaster elisae complex (Oligochaeta, Hormogastridae)

Spatial and temporal aspects of the evolution of cryptic species complexes have received less attention than species delimitation within them. The phylogeography of the cryptic complex Hormogaster elisae (Oligochaeta, Hormogastridae) lacks knowledge on several aspects, including the small-scale distribution of its lineages or the palaeogeographic context of their diversification. To shed light on these topics, a dense specimen collection was performed in the center of the Iberian Peninsula - resulting in 28 new H. elisae collecting points, some of them as close as 760m from each other- for a higher resolution of the distribution of the cryptic lineages and the relationships between the populations. Seven molecular regions were amplified: mitochondrial subunit 1 of cytochrome c oxidase (COI), 16S rRNA and tRNA Leu, Ala, and Ser (16S t-RNAs), one nuclear ribosomal gene (a fragment of 28S rRNA) and one nuclear protein-encoding gene (histone H3) in order to infer their phylogenetic relationships. Different representation methods of the pairwise divergence in the cytochrome oxidase I sequence (heatmap and genetic landscape graphs) were used to visualize the genetic structure of H. elisae. A nested approach sensu Mairal et al. (2015) (connecting the evolutionary rates of two datasets of different taxonomic coverage) was used to obtain one approximation to a time-calibrated phylogenetic tree based on external Clitellata fossils and a wide molecular dataset. Our results indicate that limited active dispersal ability and ecological or biotic barriers could explain the isolation of the different cryptic lineages, which never co-occur. Rare events of long distance dispersal through hydrochory appear as one of the possible causes of range expansion.

Hybridization relics complicate barcode-based identification of species in earthworms

Introgressive hybridization results in mito-nuclear discordance which could obscure the delimitation of closely related taxa. Although such events are increasingly reported, they have been poorly studied in earthworms. Here, we propose a method for investigating the degree of introgressive hybridization between three taxa of the Allolobophora chlorotica aggregate within two field populations (N = 67 and N = 105) using a reference data set including published DNA barcoding and microsatellite data of all known A. chlorotica lineages (N = 85). For this, we used both molecular phylogenetic and population genetic approaches. The test of correspondence between mitochondrial cytochrome c oxidase I (COI) lineages and clusters of nuclear microsatellite genotypes allowed individuals to be sorted in three categories (matching, admixed and nonmatching) and additional markers (mitochondrial NADH dehydrogenase subunit 1, nuclear Histone 3 and Internal transcribed Spacer Region 2) were used for phylogenetic reconstructions in order to check assignments. Although 15 admixed individuals were observed, no early-generation hybrids were detected within the two populations. Interestingly, 14 nonmatching individuals (i.e. with a mtDNA haplotype that did not correspond to their nuclear cluster) were detected, a pattern that would result after multiple generations of unidirectional hybridization of female from one taxon to male of the other taxon. Because earthworms are simultaneous hermaphrodites, these events of unidirectional hybridization suggest sterility of the male function in several crosses and highlight that some individuals can be misidentified if reliance is placed on COI barcodes alone. These findings could improve the use of these barcodes in earthworms for species delineation.

Fauna Europaea: Annelida - Terrestrial Oligochaeta (Enchytraeidae and Megadrili), Aphanoneura and Polychaeta

Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. This paper provides updated information on the taxonomic composition and distribution of the Annelida - terrestrial Oligochaeta (Megadrili and Enchytraeidae), Aphanoneura and Polychaeta, recorded in Europe. Data on 18 families, 11 autochthonous and 7 allochthonous, represented in our continent by a total of 800 species, are reviewed, beginning from their distinctness, phylogenetic status, diversity and global distribution, and following with major recent developments in taxonomic and faunistic research in Europe. A rich list of relevant references is appended. The Fauna Europaea Annelida - terrestrial Oligochaeta data-set, as completed in 2004, will be updated accordingly.