A new and critically endangered species and genus of Onychophora (Peripatidae) from the Brazilian savannah – a vulnerable biodiversity hotspot

An ultraconserved element probe set for velvet worms (Onychophora)

Onychophora are cryptic, soil-dwelling invertebrates known for their biogeographic affinities, diversity of reproductive modes, close phylogenetic relationship to arthropods, and peculiar prey capture mechanism. The 216 valid species of Onychophora are grouped into two families - Peripatopsidae and Peripatidae - and apart from a few relationships among major lineages within these two families, a stable phylogenetic backbone for the phylum has yet to be resolved. This has hindered our understanding of onychophoran biogeographic patterns, evolutionary history, and systematics. Neopatida, the Neotropical clade of peripatids, has proved particularly difficult, with recalcitrant nodes and low resolution, potentially due to rapid radiation of the group during the Cretaceous. Previous studies have had to compromise between number of loci and number of taxa due to limitations of Sanger sequencing and phylotranscriptomics, respectively. Additionally, aspects of their genome size and structure have made molecular phylogenetics difficult and data matrices have been affected by missing data. To address these issues, we leveraged recent, published transcriptomes and the first high quality genome for the phylum and designed a high affinity ultraconserved element (UCE) probe set for Onychophora. This new probe set, consisting of ∼ 20,000 probes that target 1,465 loci across both families, has high locus recovery and phylogenetic utility. Phylogenetic analyses recovered the monophyly of major clades of Onychophora and revealed a novel lineage from the Neotropics that challenges our current understanding of onychophoran biogeographic endemicity. This new resource could drastically increase the power of molecular datasets and potentially allow access to genomic scale data from archival museum specimens to further tackle the issues exasperating onychophoran systematics.

An updated world checklist of velvet worms (Onychophora) with notes on nomenclature and status of names

More than a decade has passed since the publication of the only world checklist available for Onychophora. During this period, numerous nomenclatural acts and taxonomic changes have been suggested within the group and a wealth of novel data has been published on many taxa. Herein, the up-to-date taxonomic scenario within Onychophora is presented, with appraisal of name status. This checklist covers both extant (Peripatidae and Peripatopsidae) and fossil taxa, and each species is accompanied by information on synonyms, type designation, holotype location, type locality, and language of original description. Additional remarks include nomenclatural inconsistencies, synonymizations, name misspellings, conflicting collecting event data, availability of taxonomically informative molecular data, etc. According to the data, 237 species are currently assigned to Onychophora: 140 of Peripatopsidae, 92 of Peripatidae, and five fossil species with unclear relationship to extant taxa. Since the previous checklist, 37 species have been added to Onychophora, representing an increase of 18.5% in the diversity described for the group. Yet, taxonomic descriptions seem slow-paced, with an average of 3.6 onychophoran species being described annually. From the taxonomic standpoint, 216 species are valid, although many of them require morphological revision and molecular characterization; 21 species exhibit major taxonomic ambiguities and have been regarded as nomina dubia. Recurrent taxonomic issues identified in the literature include inaccurate collecting event data, doubtful taxonomic assignment of molecular sequences, and non-observance of nomenclatural rules. These and other taxonomic aspects are addressed herein in the light of the directives established by the International Code of Zoological Nomenclature.

Epiperipatus puri sp. nov., a new velvet worm from Atlantic Forest in Southeastern Brazil (Onychophora, Peripatidae)

Epiperipatus ohausi (Bouvier, 1900) is the first species known from Rio de Janeiro, and more than 120 years later a new species is described in the state of Rio de Janeiro (RJ). In this study, we describe the second species in the state of Rio de Janeiro, which we are naming in honor of the indigenous population called puri who resided in southeastern coastal Brazil. The species can be diagnosed mainly by large dorsal primary papillae close to the insertion of the legs drawing a light band from the anterior to the posterior region of the body, and large dorsal primary papillae alternating on the dorsal plicae. Moreover, they are recognized in vivo by the color of the diamond-shaped marks brownish orange on the dorsal portion of the body. Epiperipatus puri sp. nov. morphologically seems to be related to Epiperipatus acacioi (Marcus & Marcus, 1995) by the shape of the primary papillae apical piece and to E. ohausi by the resemblance of dorsal papillae. The phylogeny shows a close relationship between the new species and E. ohausi in a clade with a still undescribed species from Rio de Janeiro, Brazil located within the Atlantic Forest, one of the most threatened biomes in the world.

Phylogenomic Analysis of Velvet Worms (Onychophora) Uncovers an Evolutionary Radiation in the Neotropics

Onychophora ("velvet worms") are charismatic soil invertebrates known for their status as a "living fossil," their phylogenetic affiliation to arthropods, and their distinctive biogeographic patterns. However, several aspects of their internal phylogenetic relationships remain unresolved, limiting our understanding of the group's evolutionary history, particularly with regard to changes in reproductive mode and dispersal ability. To address these gaps, we used RNA sequencing and phylogenomic analysis of transcriptomes to reconstruct the evolutionary relationships and infer divergence times within the phylum. We recovered a fully resolved and well-supported phylogeny for the circum-Antarctic family Peripatopsidae, which retains signals of Gondwanan vicariance and showcases the evolutionary lability of reproductive mode in the family. Within the Neotropical clade of Peripatidae, though, we found that amino acid-translated sequence data masked nearly all phylogenetic signal, resulting in highly unstable and poorly supported relationships. Analyses using nucleotide sequence data were able to resolve many more relationships, though we still saw discordant phylogenetic signal between genes, probably indicative of a rapid, mid-Cretaceous radiation in the group. Finally, we hypothesize that the unique reproductive mode of placentotrophic viviparity found in all Neotropical peripatids may have facilitated the multiple inferred instances of over-water dispersal and establishment on oceanic islands.

Morphological and molecular phylogeny of Epiperipatus (Onychophora: Peripatidae): a combined approach

Onychophora, or velvet worms, are a key group for understanding ecdysozoan evolution. It comprises two families: Peripatopsidae, largely of Austral distribution, and Peripatidae, which is circumtropical. The interrelationships between the members of Peripatidae present many taxonomic issues exacerbated in the radiation of the Neotropical species or Neopatida. To understand the phylogeny of Neopatida, and to test the information of such morphological characters, we gathered novel molecular and morphological datasets focusing on Neotropical specimens. Our data were analysed using a combination of parsimony and maximum likelihood for the individual and combined molecular and morphological datasets. An analysis of morphology alone was inconclusive, supporting the notion that morphological characters used in peripatid taxonomy have little power to resolve phylogenetic relationships among higher taxa in Neopatida. However, the analyses of molecular or combined data show a split of the Neotropical species into two clades, which we use to reassign genera. Epiperipatus, as currently understood, is non-monophyletic, because it includes species of monotypic genera. To avoid paraphyly of Epiperipatus, the following new combinations are proposed: Epiperipatus bouvieri (Fuhrmann, 1913), Epiperipatus hitoyensis (Oliveira et al., 2012a), Epiperipatus solorzanoi (Morera-Brenes & Monge-Nájera, 2010) and Epiperipatus sucuriuensis (Oliveira et al., 2015).

Redescription of Epiperipatus edwardsii, and descriptions of five new species of Epiperipatus from Brazil (Onychophora: Peripatidae)

Epiperipatusedwardsii(Blanchard, 1847) is redescribed based on fresh material collected near the type locality. Additionally, five new species of velvet worms of the genusEpiperipatusClark, 1913 from Brazil are described:Epiperipatushyperbolicussp. nov.,Epiperipatuslucernasp. nov.,Epiperipatustitanicussp. nov. (Holotypes deposited in MNRJ: Murici, Alagoas State),Epiperipatusbeckerisp. nov. (Holotype female deposited in MNRJ: Camacan, Bahia State) andEpiperipatusmarajoarasp. nov. (Holotype male deposited in MZUSP: Breves, Marajó island, Pará State). The peculiar shape of the primary papillae (artichoke-like) ofE.titanicussp. nov. andE.beckerisp. nov. is documented for the first time.Epiperipatustitanicussp. nov. has the largest number of pairs of oncopods (38 for males and 39 for females) among the Brazilian Onychophora. We also provide an identification key for Brazilian species ofEpiperipatus.

The ‘Peripatos' in Eurogondwana? — Lack of evidence that southeast Asian onychophorans walked through Europe

Onychophorans, or velvet worms, are cryptic but extremely charismatic terrestrial invertebrates that have often been the subject of interesting biogeographic debate. Despite great interest, a well resolved and complete phylogeny of the group and a reliable chronogram have been elusive due to their broad geographic distribution, paucity of samples, and challenging molecular composition. Here we present a molecular phylogenetic analysis of Onychophora that includes previously unsampled and undersampled lineages and we analyse the expanded dataset using a series of nested taxon sets designed to increase the amount of information available for particular subclades. These include a dataset with outgroups, one restricted to the ingroup taxa, and three others for Peripatopsidae, Peripatidae and Neopatida (= the Neotropical Peripatidae). To explore competing biogeographic scenarios we generate a new time tree for Onychophora using the few available reliable fossils as calibration points. Comparing our results to those of Cyphophthalmi, we reconsider the hypothesis that velvet worms reached Southeast Asia via Eurogondwana, and conclude that a more likely scenario is that they reached Southeast Asia by rafting on the Sibumasu terrane. Our phylogenetic results support the reciprocal monophyly of both families as well as an early division between East and West Gondwana, also in both families, each beginning to diversify between the Permian and the Jurassic. Peripatopsidae clearly supports paraphyly of South Africa with respect to southern South America (Chile) and a sister group relationship of the Southeast Asian/New Guinean Paraperipatus to the Australian/New Zealand taxa. The latter includes a clade that divides between Western Australia and Eastern Australia and two sister clades of trans-Tasman species (one oviparous and one viviparous). This pattern clearly shows that oviparity is secondarily derived in velvet worms. Peripatidae finds a sister group relationship between the Southeast Asian Eoperipatus and the West Gondwanan clade, which divides into the African Mesoperipatus and Neopatida. The latter shows a well supported split between the Pacific Oroperipatus (although it is unclear whether they form one or two clades) and a sister clade that includes the members of the genera Peripatus, Epiperipatus, Macroperipatus and representatives of the monotypic genera Cerradopatus, Plicatoperipatus and Principapillatus. However, Peripatus, Epiperipatus and Macroperipatus are not monophyletic, and all the species from the monotypic genera are related to geographically close species. The same goes for the type species of Macroperipatus (from Trinidad, and sister group to other Trinidad and Tobago species of Epiperipatus) and Epiperipatus (from French Guiana, and related to other Guyana shield species of Epiperipatus and Peripatus). Geographic structure within Neopatida is largely obscured by an unresolved backbone, but many well supported instances of generic non-monophyly challenge the current taxonomic framework, which has often relied on anatomical characters that are untested phylogenetically.

Revision of Tasmanian viviparous velvet worms (Onychophora : Peripatopsidae) with descriptions of two new species

The restricted distribution of viviparous onychophorans in Tasmania has long been a subject of discussion, but their evolutionary history remains unclear. We applied morphological, molecular and karyological methods to assess the taxonomy and phylogenetic relationships of the four viviparous species reported from Tasmania, including Tasmanipatus barretti, T. anophthalmus and two undescribed species previously referred to as ‘Tasmania’ sp. 1 and sp. 2. We demonstrate that all four species can be unambiguously distinguished based on independent character sets. The two ‘Tasmania’ species, which were previously thought to be cryptic, proved to exhibit a set of distinct morphological characters. Molecular phylogenetic analyses revealed that the four species belong to a major clade that includes Peripatoides from New Zealand, and that species from the two landmasses show reciprocal monophyly within this clade. Within the Tasmanian clade, T. anophthalmus is more closely related to the two ‘Tasmania’ species than to T. barretti. Based on this relationship and the lack of morphological and/or karyological characters supporting the Tasmanian viviparous clade, we erect two new genera to accommodate the two ‘Tasmania’ species (Diemenipatus, gen. nov.) and T. anophthalmus (Leucopatus, gen. nov.). An emended diagnosis followed by a redescription of T. barretti is provided and ‘Tasmania’ sp. 1 and sp. 2 are formally described as D. taiti, gen. et sp. nov. and D. mesibovi, gen. et sp. nov., respectively.