A review of Palaemonella (Decapoda: Caridea: Palaemonidae), with clarification of the taxonomic status of Cuapetes americanus, Eupontonia and Vir.

The pantropical genus Palaemonella Dana, 1852 (Caridea: Palaemonidae) currently includes 27 species of free-living and symbiotic marine shrimps. The monophyly of Palaemonella with respect to several closely related genera, however, has been questioned by recent analyses. We tested the monophyly of Palaemonella based on multigene phylogenetic analysis and the genus was revealed to be a paraphyletic assemblage by inclusion of species of the genera Eupontonia Bruce, 1971 and Vir Holthuis, 1952, and two genetic lineages of the western Atlantic Cuapetes americanus (Kingsley, 1878). We recognise one of the latter lineages as the previously described Periclimenes rhizophorae Lebour, 1949. Eupontonia and Vir are synonymised with Palaemonella . We also transfer Cuapetes americanus and Periclimenes rhizophorae to Palaemonella . Species previously assigned to Vir were revised; V. colemani Bruce, 2003, V. orientalis (Dana, 1852), V. philippinensis Bruce & Svoboda, 1984 and V. smiti Fransen & Holthuis, 2007 are regarded as valid species of Palaemonella ; Vir longidactylus Marin, 2008 is synonymised with P. smiti ; and the status of V. euphyllius Marin & Anker, 2005 remains unresolved. Palaemonella is currently regarded as a taxon with variable states of two main diagnostic characters, i.e. the plesiomorphic mandibular palp (fully reduced in P. americana ) and the hepatic tooth (fully reduced in former species of Vir and Eupontonia - evidently due to symbiotic modes of life). ZooBank: urn:lsid:zoobank.org:pub:7EEBC655-7EDE-4E46-BCB2-2A3BA16ED7DD.

Molecular phylogeny and historical biogeography of marine palaemonid shrimps (Palaemonidae: Palaemonella-Cuapetes group).

Palaemonidae is the most speciose shrimp family within the infraorder Caridea, composed predominately of freshwater species and marine symbiotic species. The subject of this study is a clade of mainly free-living marine taxa representing a basally separated lineage from most of the symbiotic marine palaemonid genera. Phylogenetic and biogeographic relationships were explored by analysing sequence data from two mitochondrial and four nuclear markers. Maximum likelihood and Bayesian analyses, based on sequences from 52 species of 11 genera, provided similar tree topologies revealing the genera Palaemonella, Cuapetes and Eupontonia as non-monophyletic groups. Divergence time and S-DIVA analyses reveals that the focal clade originated during the Late Cretaceous in the Paleotethys region respective to the present Indo-West Pacific area, a minor part of which spread out to the eastern Pacific during the Paleocene, followed by further migration into the Atlantic (before the closure of the Panama Isthmus). The ancestral state reconstruction of host associations revealed eight independent symbiotic lineages originating from free-living ancestors, entering primary symbioses. The first associations with Cnidaria are estimated to have evolved in the Eocene. This study points to the need of taxonomic revisions of the non-monophyletic genera concerned.

A new species of scleractinian associated shrimp of the genus Palaemonella (Crustacea, Decapoda, Palaemonidae) with a redescription of Palaemonella orientalis Dana, 1852.

A new species of Palaemonella, P. rubrolineata sp. nov., is described on the basis of material collected from pocilloporid corals in Indonesia and Vanuatu. The new species is most closely related to P. orientalis, another tropical Indo-West Pacific species usually found in association with pocilloporid and acroporid corals. The new species can be distinguished from P. orientalis based on the presence of a hepatic spine, the more slender rostrum, body and longer appendages, the pleura of the fifth abdominal segment having a posteroventral tooth, the absence of distal rows of long serrate setae on the fingers of the first pereiopods, and in having the cutting edges of the second chela as well as the joints of the pereiopods dark red colored.

Madangella koumacensis, a new species of palaemonid shrimps (Decapoda: Palaemonidae) from New Caledonia.

A second species of the recently established genus Madangella Frolová Duris is described from New Caledonia. Although the single available specimen lacks both second pereiopods, the new species distinctly differs from the only other representative of the genus, M. altirostris Frolová Duris, 2018 from Papua New Guinea, and can be easily distinguished from the latter by the more elongate and distally tapering rostrum, two subterminal ventral rostral teeth, the carpus of the first pereiopod being subequal to the merus length, and the sixth pleomere being short and stout, distinctly less than 2 times longer than deep. The examined specimen was confirmed as representative of a species separate from M. altirostris also by molecular comparisons of the 16S rRNA and COI mtDNA gene markers. The genus Madangella thus currently consists of two southwestern Pacific species.

Madangella altirostris, a new genus and species of palaemonid shrimps (Crustacea: Decapoda: Palaemonidae) from Papua New Guinea.

A single ovigerous female specimen of marine shrimp of the family Palaemonidae collected from Madang Province, N.E. Papua New Guinea, was recognized as a representative of a new genus and species. Due to the presence of a sternal thoracic process, 3 pairs of posterior telson cuspidate setae, and the simple ambulatory dactyli, as well as the lack of branchiae on the two posterior maxillipeds, the new species clearly belongs to the assemblage of primarily free-living palaemonid taxa surrounding the speciose genera Cuapetes and Palaemonella. As the specimen possesses a short leaf-like rostrum, slender second pereiopods with small chelae similar to and not noticeably longer than the first pereiopods and very slender simple ambulatory dactyli, the specimen is without parallel within this assemblage and clearly represents a new genus. Its position within the Cuapetes/Palaemonella lineage of genera is also confirmed by a molecular comparison. The specimen is described and illustrated as a new genus and species.