Benchmarking global biodiversity of decapod crustaceans (Crustacea: Decapoda)

A new assessment of the global biodiversity of decapod Crustacea (to 31 December 2022) records 17,229 species in 2,550 genera and 203 families. These figures are derived from a well-curated dataset maintained on the online platform DecaNet, a subsidiary of the World Register of Marine Species (WoRMS). Distinct phases are recognised in the discovery process (as measured by species descriptions) corresponding to major historical and geopolitical time periods, with the current rate of species descriptions being more than three times higher than in the Victorian age of global exploration. Future trends are briefly explored, and it is recognised that a large number of species remain to be discovered and described

The Magnitude of Global Marine Species Diversity

Background: The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be discovered. Results: There are ∼226,000 eukaryotic marine species described. More species were described in the past decade (∼20,000) than in any previous one. The number of authors describing new species has been increasing at a faster rate than the number of new species described in the past six decades. We report that there are ∼170,000 synonyms, that 58,000–72,000 species are collected but not yet described, and that 482,000–741,000 more species have yet to be sampled. Molecular methods may add tens of thousands of cryptic species. Thus, there may be 0.7–1.0 million marine species. Past rates of description of new species indicate there may be 0.5 ± 0.2 million marine species. On average 37% (median 31%) of species in over 100 recent field studies around the world might be new to science. Conclusions: Currently, between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely. More species than ever before are being described annually by an increasing number of authors. If the current trend continues, most species will be discovered this century

Caught in speciation? A new host for Conchodytes meleagrinae Peters, 1852 (Decapoda, Caridea, Palaemonidae)

Fransen, Charles H.J.M., Reijnen, Bastian T. (2013): Caught in speciation? A new host for Conchodytes meleagrinae Peters, 1852 (Decapoda, Caridea, Palaemonidae). Zootaxa 3721 (3): 265-280, DOI: http://dx.doi.org/10.11646/zootaxa.3721.3.

Two new species of Hippolyte from the Tropical Central and East Atlantic (Crustacea, Decapoda, Caridea)

Fransen, Charles H.J.M., Grave, Sammy De (2019): Two new species of Hippolyte from the Tropical Central and East Atlantic (Crustacea, Decapoda, Caridea). Zootaxa 4550 (2): 201-220, DOI: https://doi.org/10.11646/zootaxa.4550.2.

Two new species of shrimp of the Indo-West Pacific genus Hamodactylus Holthuis, 1952 (Crustacea: Decapoda: Palaemonidae)

Two new alcyonacean-associated species, Hamodactylus paraqabai sp. nov. from Papua New Guinea and the Great Barrier Reef and H. pseudaqabai sp. nov. from Indonesia and Malaysia, are described and illustrated. To evaluate the status of the new species and their relationship within the genus Hamodactylus Holthuis, 1952, we combined morphology and phylogenetic analyses based on the cytochrome c oxidase subunit I (COI) mitochondrial gene. Both new species are closely related, with their mutual genetic divergence reaching 3-4%. They are further most related to Hamodactylus aqabai Bruce & Svoboda, 1983, originally described from the Red Sea. Both new species are distinguished from all other congeners by the presence of multiple teeth distally on the cutting edges of the fingers of the first pereiopods, and, in the case of H. paraqabai sp. nov., by a full reduction of the fixed finger on the second pereiopod chela. In H. pseudaqabai sp. nov. the finger is greatly reduced to a small but distinct stub, and the telson bears only a single pair of dorsal spines, as in H. aqabai. A key for the identification of all six currently known species is proposed

Coming out of your shell or crawling back in: Multiple interphylum host switching events within a clade of bivalve- A nd ascidian-associated shrimps (Caridea: Palaemonidae)

Marine symbiotic Palaemonidae, comprising over 600 species, live in association with marine invertebrates of different phyla, like Cnidaria, Echinodermata, Mollusca, Porifera, and Tunicata. A phylogenetic study is performed on a clade of bivalve- A nd ascidian-associated endosymbiotic shrimp species (Caridea: Palaemonidae), using morphological and molecular data. A Total Evidence approach is used in order to include all currently known ingroup species in an evolutionary framework. Ancestral state reconstruction analyses are performed to identify host-switching events and ancestral ranges. The clade, including Ascidonia, Conchodytes, Dactylonia, Odontonia, and Pontonia, and various smaller genera, is recovered as monophyletic, with an ascidian-associated ancestral host state. At least six interphylum host switches are tentatively identified, with members of Odontonia and Notopontonia switching back to an ascidian host affiliation after the ancestral host switch of the clade including Conchodytes, Odontonia and related genera, from an ascidian-to a bivalve host. The clade including Ascidonia and Pontonia was recovered to have an ancestor with an East Pacific/Atlantic distribution. The other studied genera remained in the original ancestral Indo-West Pacific range. We hypothesize that similar internal environments of shrimp hosts from different phyla will function as hot spots for interphylum host switching in various lineages of symbionts

On a collection of deep-water shrimp (Crustacea, Decapoda) from the Dutch Caribbean, with the description of a new species of Pseudocoutierea

Olthof, Gabriël, Becking, Leontine E., Fransen, Charles H.J.M. (2018): On a collection of deep-water shrimp (Crustacea, Decapoda) from the Dutch Caribbean, with the description of a new species of Pseudocoutierea. Zootaxa 4415 (3): 533-548, DOI: https://doi.org/10.11646/zootaxa.4415.3.