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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.
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Rare yet everywhere: phylogenetic position of the enigmatic deep-sea shrimp Physetocaris microphthalma Chace, 1940 (Decapoda, Caridea)
The mysterious deep-sea shrimp Physetocaris microphthalma Chace, 1940 remains a challenge for the understanding of caridean shrimp systematics. Upon first description in 1940, the unique morphology in combination with lack of material made the allocation of P. microphthalma to any family or superfamily difficult, therefore the monotypic superfamily Physetocaridoidea and family Physetocarididae were described. The rarity of the species, only documented a few times in scientific literature, in combination with a circumglobal distribution, makes the advancement of the systematics and biology of this shrimp challenging. Current literature places Physetocaridoidea as a superfamily with a sister relationship to Pandaloidea but this relationship has never been tested using molecular data. Recent expeditions to the northern Gulf of Mexico and north-eastern Pacific Ocean provided fresh material for inclusion in phylogenetic analyses. Here, we used a molecular systematics approach to investigate the phylogenetic placement of this species within the infraorder Caridea and test for cryptic diversity across oceanic basins. We sequenced five genes (12S rRNA, 16S rRNA, H3, NaK and PEPCK) and built phylogenetic trees including specimens across Pandaloidea and other carideans (n = 75) using maximum-likelihood and Bayesian approaches. Our results strongly support the inclusion of P. microphthalma within the family Pandalidae and superfamily Pandaloidea, indicating that the superfamily Physetocaridoidea and family Physetocaridae are not valid. In addition, the inclusion of specimens from the Atlantic and Pacific Oceans does not support evidence of cryptic diversity, suggesting the global distribution of P. microphthalma. This is the first study to provide genetic data for this species, resulting in an updated classification for the infraorder Caridea and highlighting that deep-pelagic species can be rare yet still widely distributed.
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- Award ID(s):
- 1829812
- PAR ID:
- 10485153
- Editor(s):
- Ahyong, Shane
- Publisher / Repository:
- CSIRO Publishing
- Date Published:
- Journal Name:
- Invertebrate Systematics
- Volume:
- 37
- Issue:
- 8
- ISSN:
- 1445-5226
- Page Range / eLocation ID:
- 529-537
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1071/IS23024
