Straightening the striped chaos: systematics and evolution of Trypanosyllis and the case of its pseudocryptic type species Trypanosyllis krohnii (Annelida, Syllidae)

Integrative taxonomy in Syllis prolifera (Annelida, Syllidae): from a unique cosmopolitan species to a complex of pseudocryptic species

Syllis prolifera (Syllidae, Syllinae) is an abundant species of marine annelids commonly found in warm to temperate waters worldwide. Although morphological variability occurs among populations, S. prolifera has long been considered a cosmopolitan species, widely distributed in coastal environments, including acidified and polluted areas. However, the increasing number of cases of cryptic and pseudocryptic speciation in several polychaete families in recent years has led us to question whether S. prolifera represents a single globally distributed taxon or is a species complex. To address this question, we conducted an integrative study, combining morphological, ecological and molecular data of 52 S. prolifera specimens collected in different localities across the western Mediterranean Sea and the Gulf of Cadiz. Our phylogenetic and species delimitation analyses that included two mitochondrial DNA markers (COI and 16S rRNA ) were congruent in not considering S. prolifera a unique entity. Five distinct lineages that can also be recognised by certain morphological and ecological traits were identified from these analyses instead. Overall, our study does not support the homogeneity of S. prolifera across the Mediterranean Sea, providing a new example of pseudocrypticism in marine invertebrates.

Spineless and overlooked: DNA metabarcoding of autonomous reef monitoring structures reveals intra- and interspecific genetic diversity in Mediterranean invertebrates

The ability to gather genetic information using DNA metabarcoding of bulk samples obtained directly from the environment is crucial to determine biodiversity baselines and understand population dynamics in the marine realm. While DNA metabarcoding is effective in evaluating biodiversity at community level, genetic patterns within species are often concealed in metabarcoding studies and overlooked for marine invertebrates. In the present study, we implement recently developed bioinformatics tools to investigate intraspecific genetic variability for invertebrate taxa in the Mediterranean Sea. Using metabarcoding samples from Autonomous Reef Monitoring Structures (ARMS) deployed in three locations, we present haplotypes and diversity estimates for 145 unique species. While overall genetic diversity was low, we identified several species with high diversity records and potential cryptic lineages. Further, we emphasize the spatial scale of genetic variability, which was observed from locations to individual sampling units (ARMS). We carried out a population genetic analysis of several important yet understudied species, which highlights the current knowledge gap concerning intraspecific genetic patterns for the target taxa in the Mediterranean basin. Our approach considerably enhances biodiversity monitoring of charismatic and understudied Mediterranean species, which can be incorporated into ARMS surveys.

Morphological and molecular study of Syllinae (Annelida, Syllidae) from Bermuda, with the description of five new species

Although polychaetes from the Bermuda Archipelago have been studied since the beginning of the twentieth century, syllids have been particularly neglected in this area, which is surprising considering this family is usually a dominant group in marine benthic ecosystems. To fill this knowledge gap, we have carried out an extensive analysis of Bermudan Syllidae, combining morphological and molecular data including four nuclear and mitochondrial markers (cytochrome c oxidase subunit I, 18S rRNA, 16S rRNA and 28S rRNA). We have identified and established the phylogenetic position of five new species, Haplosyllis anitae n. sp., Haplosyllis guillei n. sp., Haplosyllis larsi n. sp., Haplosyllis vassiae n. sp. and Syllis laiae n. sp., together with Haplosyllis cf. cephalata. Overall, our results extend the knowledge on the diversity of Syllidae in Bermuda, increasing the number of species present in the area to 25. Our results also recover Opisthosyllis and Syllis as non-monophyletic genera, for which traditional diagnostic morphological features do not accurately reflect their evolutionary histories, and thus we propose that these groups should be reorganized based on molecular characters.

A synopsis of Salvatoria McIntosh, 1885 (Annelida: Syllidae: Exogoninae) from Brazilian coastal and oceanic waters

We compiled the records for the genus Salvatoria from Brazilian coastal and oceanic habitats, collected by several projects along the years. Here we present 12 species, eight of which already reported-S. breviarticulata comb. nov., S. clavata, S. euritmica, S. heterocirra, S. limbata, S. longiarticulata comb. nov., S. neapolitana and S. cf. nitidula-with comments regarding the confidence of some of these records. We also describe three new species, S. marielleae n. sp. and Salvatoria nitiduloides n. sp., based on material from Fernando de Noronha and Trindade islands, off the Northeastern Brazilian coast, and S. ypsiloides n. sp., from Fernando de Noronha and also, Campos Basin, off Southeastern Brazilian coast, in depths down to 970 m. Finally, we report a probably undescribed species, Salvatoria sp., represented by only one specimen lacking median antenna, preventing us to proceed with further identification properly. A dichotomous identification key and a comparative table with morphological data of specimens belonging to these species are also provided.

On the Diversity of Phyllodocida (Annelida: Errantia), with a Focus on Glyceridae, Goniadidae, Nephtyidae, Polynoidae, Sphaerodoridae, Syllidae, and the Holoplanktonic Families

Phyllodocida is a clade of errantiate annelids characterized by having ventral sensory palps, anterior enlarged cirri, axial muscular proboscis, compound chaetae (if present) with a single ligament, and of lacking dorsolateral folds. Members of most families date back to the Carboniferous, although the earliest fossil was dated from the Devonian. Phyllodocida holds 27 well-established and morphologically homogenous clades ranked as families, gathering more than 4600 currently accepted nominal species. Among them, Syllidae and Polynoidae are the most specious polychaete groups. Species of Phyllodocida are mainly found in the marine benthos, although a few inhabit freshwater, terrestrial and planktonic environments, and occur from intertidal to deep waters in all oceans. In this review, we (1) explore the current knowledge on species diversity trends (based on traditional species concept and molecular data), phylogeny, ecology, and geographic distribution for the whole group, (2) try to identify the main knowledge gaps, and (3) focus on selected families: Alciopidae, Goniadidae, Glyceridae, Iospilidae, Lopadorrhynchidae, Polynoidae, Pontodoridae, Nephtyidae, Sphaerodoridae, Syllidae, Tomopteridae, Typhloscolecidae, and Yndolaciidae. The highest species richness is concentrated in European, North American, and Australian continental shelves (reflecting a strong sampling bias). While most data come from shallow coastal and surface environments most world oceans are clearly under-studied. The overall trends indicate that new descriptions are constantly added through time and that less than 10% of the known species have molecular barcode information available.

New symbiotic association in marine annelids: ectoparasites of comb jellies

A new genus of ectoparasitic marine annelids living on ctenophores, Ctenophoricola gen. nov., is described and its feeding behaviour, reproduction and developmental stages are discussed. Its unusual morphology challenged its placement within the known marine families. However, analyses of mitochondrial and nuclear sequence data showed the new genus as member of the Alciopini, a group of holopelagic annelids included within the Phyllodocidae. Ctenophoricola masanorii sp. nov. from Japan and Ctenophoricola rousei sp. nov. from the Canary Islands (Spain) are described. A third species from the Gulf of California is not formally described because the specimens are in poor condition. The new genus is characterized by having: 1) two distinctive body regions, the anterior with reduced parapodia lacking chaetae, and the posterior with long parapodia and chaetae and 2) a pair of large, elongate lensed eyes. These eyes are here described using histology and 3D reconstruction based on a Californian specimen. The two new species mainly differ in colour pattern, shape of parapodia, number of chaetae and body ciliation.

Hidden diversity within the Diopatra cuprea complex (Annelida: Onuphidae): morphological and genetics analyses reveal four new species in the south-west Atlantic

Diopatra is the most species-rich genus of Onuphidae with about 60 species. Although 14 species have been reported for Brazil, the cosmopolitan D. cuprea is the most commonly reported from the area, including populations with a large morphological diversity. To better elucidate this species complex, we use morphological and molecular data, and reveal a hidden diversity. Thus, we describe four new species (D. hannelorae sp. nov., D. marinae sp. nov., D. pectiniconicum sp. nov. and D. victoriae sp. nov.) and discuss their geographical and bathymetrical distributions. None of the analysed specimens could be identified as D. cuprea based on available sequences. New taxonomic characters were highlighted, including jaw morphology, which was the determinant factor to differentiate D. marinae from D. victoriae. Phylogenetic analysis indicates three (COI and ND4) or four (concatenated) lineages, because D. marinae was not always reciprocally monophyletic. Sequence-based species delimitation also indicates three to five species, depending on the method used. Inter- and intragroup genetic divergence and haplotype network analysis supported four species. The divergence time among species indicates that Pleistocene sea-level fluctuations and the Vitória–Trindade chain limited the gene flow between northern and southern populations and contributed to the emergence of species, mainly in the case of D. marinae and D. victoriae.

Multilocus data reveal cryptic species in the Atlantic seabob shrimp Xiphopenaeus kroyeri (Crustacea: Decapoda)

The recognition of cryptic biodiversity provides valuable insights for the management of exploited species. The Atlantic seabob shrimp (Xiphopenaeus kroyeri) is a commercially important fishery resource in the Guianan ecoregion, South America. Previous research in Brazil suggested the presence of cryptic species within the genus. Here, we confirm this presence and delimit the species by applying a multilocus approach based on two mitochondrial (COI and cytb) and two nuclear (PEPCK and NaK) genes. Species boundaries were tested using BPP, GMYC and bPTP delimitation algorithms. These analyses provided strong support for three clades within the genus Xiphopenaeus, including one undescribed clade, which occurs sympatrically with X. kroyeri in the Western Atlantic. Unexpectedly, this undescribed clade is more closely related to the Pacific Xiphopenaeus riveti than to their Atlantic congener. Our DNA-based species delimitation was further supported by new ecological information on habitat and morphology (colour). We also expand the known distribution range of the cryptic species, currently restricted to Brazil, to include French Guiana, Suriname and Colombia. Our findings have important consequences for the management of the species, in terms of both biodiversity management and fisheries management.

Cosmopolitan polychaetes – fact or fiction? Personal and historical perspectives

In the biogeographical and taxonomical literature before the 1980s there was a wide perception that widespread, often referred to as ‘cosmopolitan’, species were very common among polychaetes. Here we discuss the origins of this perception, how it became challenged, and our current understanding of marine annelid distributions today. We comment on the presence of widely distributed species in the deep sea and on artificially extended ranges of invasive species that have been dispersed by anthropogenic means. We also suggest the measures needed to revolve the status of species with reported cosmopolitan distributions and stress the value of museum collections and vouchers to be associated with DNA sequences in resolving species distributions.

Phylogenetic relationships and evolution of reproductive modes within flattened syllids (Annelida : Syllidae) with the description of a new genus and six new species

Syllid annelids from the so-called ‘ribbon clade’ are flattened, ribbon-shaped worms of the genera Parahaplosyllis Hartmann-Schröder, 1990, Eurysyllis Ehlers, 1864, Xenosyllis Marion & Bobretzky, 1875, Trypanosyllis Claparède, 1864, Ramisyllis Glasby, Schroeder & Aguado, 2012, Trypanobia Imajima & Hartman, 1964, Plakosyllis Hartmann-Schröder, 1956, Pseudosyllis Grube, 1863 and Trypanedenta Imajima & Hartman, 1964. Some species possess a remarkable reproductive strategy using multiple stolons that has been recently suggested to be ancestral to the group. Here, to evaluate the evolution of reproductive modes in the group, we assess, for the first time, the phylogenetic relationships within the ribbon clade and related genera. We collected new material of Trypanobia and Trypanosyllis from Japan, Spain, Philippines and Indonesia and sequenced it for the nuclear markers 18S rRNA and the mitochondrial markers 16S rRNA and cytochrome c oxidase I for phylogenetic inference and also performed ancestral character reconstruction for the reproductive strategy in the entire group. Formal taxonomic descriptions of a new genus and six new species are provided. The new genus, Trypanospina, gen. nov., is characterised by the spines that cover its surface. Most genera within the ‘ribbon clade’ are monophyletic and the relationships appeared well supported in most cases. However, our phylogenetic hypotheses are not conclusive in regard to the relationships of the genera Trypanedenta and Trypanobia, nor to the status of those to genera as distinctive, since they seem to be paraphyletic and they appear in low-supported clades. In contrast, our results shed light on the evolution of the reproductive modes within the group, showing that scissiparity (development of a single stolon each time) is the ancestral character for the entire group and gemmiparity (development of more than one stolon at the same time) then appeared twice in two independent clades.

Polychaetes of Greece: an updated and annotated checklist

BACKGROUND

The last annotated checklist of marine polychaetes in Greece was published in 2001. Since then, global taxonomic progress, combined with many new species records for Greece, required a thorough review of the taxonomic, nomenclatural and biogeographic status of the national species list. This checklist revises the status of all extant polychaete species reported from the Greek Exclusive Economic Zone since 1832. The work was undertaken as part of the efforts on compiling a national species inventory (Greek Taxon Information System initiative) in the framework of the LifeWatchGreece Research Infrastructure.

NEW INFORMATION

This checklist comprises an updated and annotated inventory of polychaete species in Greek waters, compiled from literature reports, online databases, museum collections and unpublished datasets. The list provides information on 836 species-level taxa from Greece, of which 142 are considered questionable. An additional 84 species reported in the past are currently considered absent from Greece; reasons for the exclusion of each species are given. Fourteen species are reported here for the first time from Greek waters. At least 52 species in the present list constitute in fact a complex of cryptic or pseudo-cryptic species. Forty-seven species are considered non-native to the area. In addition to the species-level taxa reported in this checklist, eleven genera have been recorded from Greece with no representatives identified to species level. One replacement name is introduced. For each species, a comprehensive bibliographic list of occurrence records in Greece and the synonyms used in these publications are provided as supplementary material. Where necessary, the taxonomic, nomenclatural or biogeographic status is discussed. Finally, the findings are discussed in the wider context of Mediterranean polychaete biogeography, taxonomic practice and worldwide research progress.