Differentiation of three common deep-water hermit crabs (Crustacea, Decapoda, Anomura, Parapaguridae) from the South African demersal abundance surveys, including the description of a new species of Paragiopagurus Lemaitre, 1996

Abstract

Deep-water hermit crabs of the family Parapaguridae can be abundant (up to 20 kg or 1000 hermit crab individuals per haul) in the trawl bycatch collected during South African demersal abundance research surveys. Until recently, only two parapagurid species had been recognized in the bycatch; Parapagurus bouvieri Stebbing, 1910, and Sympagurus dimorphus (Studer, 1883). Detailed examination of numerous samples of parapagurid specimens from research surveys revealed the existence of a third, undescribed species previously confounded with S. dimorphus, but in fact belonging to a different genus. This new species, Paragiopagurus atkinsonae sp. n. is the 25th in the genus Paragiopagurus Lemaitre, 1996, and has been found only in a small region on the West Coast shelf of South Africa, at depths of 199–277 m. The species is herein fully described and illustrated, including colour images, µCT scans of selected body parts, and CO1 barcode data. The new species is morphologically most similar to P. ventilatus Lemaitre, 2004, a species associated with hydrothermal vents, but differs in armature of the fourth antennal segment (armed with a spine on the dorsolateral distal angle vs. unarmed in P. ventilatus); setation of the antennal flagella (nearly naked vs. with dense setae in P. ventilatus); plumose setation on the third maxillipeds and basal segments of chelipeds (absent vs. present in P. ventilatus); number of rows of scales on the propodal rasp of pereopod 4 (two or three rows vs. one row in P. ventilatus); and degree of telson asymmetry (weakly asymmetrical vs. strongly asymmetrical in P. ventilatus). Paragiopagurus atkinsonae sp. n. is superficially similar to S. dimorphus, with males of the two species showing the same extreme degree of sexual dimorphism on the right cheliped, general light orange colouration, and frequent use of colonial zoanthid carcinoecia for pleonal protection. To aid in future identifications and to facilitate data gathering during surveys, a comparison of P. atkinsonae sp. n. with S. dimorphus is provided, along with descriptions of colouration and photographs of live specimens of all three parapagurid species. Information on taxonomy of the species is summarized, as well as knowledge of their distribution in the demersal research survey regions of South Africa.

A micro X-ray computed tomography dataset of South African hermit crabs (Crustacea: Decapoda: Anomura: Paguroidea) containing scans of two rare specimens and three recently described species

“…The dataset presented in this study was primarily created to visually support descriptive taxonomic studies of hermit crabs [ 5 , 6 ]. However, the 3D raw data that are publicly made available here can also be used for morphological comparisons, including species validations, without having to examine the physical specimen.…”

MicroCT imaging applied to description of a new species of Pagurus Fabricius, 1775 (Crustacea: Decapoda: Anomura: Paguridae), with selection of three-dimensional type data

“…Genetic barcodes of the mitochondrial cytochrome c oxidase subunit I (COI) fragment were generated at the Aquatic Genomics Research Platform of the National Research Foundation—South African Institute for Aquatic Biodiversity, Grahamstown, using a methodology described previously [27]. Tissue was either taken from eggs of ovigerous females or the chelae and carpus of the right cheliped, and, for small specimens, from the coxae and ischia of different pereopods.…”

“…Tissue was either taken from eggs of ovigerous females or the chelae and carpus of the right cheliped, and, for small specimens, from the coxae and ischia of different pereopods. DNA extraction, PCR amplification of the COI mitochondrial DNA fragment, purification of amplicons, fluorescently-labelled terminator cycle sequencing and sequence analysis proceeded as documented by Landschoff & Lemaitre [27]. One specimen each of P .…”

“…The latter, for example, brought new insights into the evolution of the hermit crab-derived king crabs. Nevertheless, μCT has not seen many applications in taxonomy of higher crustaceans, although Landschoff & Lemaitre [27] and Landschoff & Rahayu [28] included single μCT images or videos of calcified characters to inform the species description of paguroids, commonly known as hermit crabs. In this study, the discovery of a new hermit crab from South Africa is utilized to apply and test the technique of μCT for the description of a new decapod crustacean species.…”

Population structure and morphology of South African deep‐water parapagurid hermit crabs

“…Two of these species, Sympagurus dimorphus (Studer, 1883) and Parapagurus bouvieri (Stebbing, ), are abundant on the continental shelf and slope around South Africa (Atkinson & Sink, ; Lange & Griffiths, ), although several other parapagurid species have also been reported to occur in the region at lower densities (Landschoff & Lemaitre, ). Colloquially referred by fishermen as “monkey nuts,” South African populations of S. dimorphus and P. bouvieri associate with the zoanthid species Epizoanthus paguricolai (Carlgren, ) and E. carcinophilus (Carlgren, ), respectively.…”