Odontonia plurellicola sp. n. and Odontonia bagginsi sp. n., two new ascidian-associated shrimp from Ternate and Tidore, Indonesia, with a phylogenetic reconstruction of the genus (Crustacea, Decapoda, Palaemonidae)

Abstract

Two new species of palaemonid shrimp associated with ascidian hosts, Odontonia bagginsi sp. n. from Tidore and Odontonia plurellicola sp. n., from Ternate, Indonesia are described and figured. Through phylogenetic analyses based on both morphological and molecular datasets (mitochondrial Cytochrome c oxidase subunit I gene and the 16S mitochondrial ribosomal gene) of the genus Odontonia, the phylogenetic positions of the new species have been reconstructed. Scanning Electron Microscopy has been used to observe additional characters on dactyli of the ambulatory pereiopods. Odontonia plurellicola sp. n. appears to be more closely related to O. simplicipes and O. seychellensis, but it differs most notably in the morphology of the rostrum and mouthparts. Odontonia plurellicola sp. n. appears to be the only Odontonia species living inside a phlebobranch ascidian Plurella sp. Odontonia bagginsi sp. n. is closely related to O. sibogae, but differs markedly in the abundance of setae on the propodi of the ambulatory pereiopods. In the present paper, O. maldivensis Fransen, 2006 is regarded as a junior synonym of O. rufopunctata Fransen, 2002 based on both morphological and molecular aspects.

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

“…The basal placement of O. kerangcaris is as expected, since the species' host and morphological features were found by Fransen et al (2021) coming out of your shell or crawling back in | 10.1163/18759866-bja10030 to resemble that of related, bivalve-associated genera such as Conchodytes. The placement of O. rufopunctata is less expected, but the placement away from the other species within the genus was also recovered in a previous study based on dna and morphological features (De Gier & Fransen, 2018). As mentioned above, the other species seem to be grouping in two separate lineages in the concatenated analysis: one lineage including O. katoi, O. seychellensis and O. kerangcaris (and one specimen of Dactylonia holthuisi); and one lineage including O. bagginsi and O. sibogae.…”

“…The potential explanation for this can be found in the only successfully sequenced marker of O. katoi, 16S. Odontonia katoi can therefore only be compared to other 16S sequences, in this case being limited to only O. sibogae and O. rufopunctata (see De Gier & Fransen, 2018). Due to O. simplicipes and O. compacta being only represented by morphological data, and O. katoi, O. kerangcaris, O. plurellicola, O. bagginsi, and O. seychellensis only being represented by one molecular marker, the relation between these species and the other species in Odontonia is far from resolved.…”

“…3, upper branch of clade iiic). Previous phylogenetic analyses by Fransen & Reijnen (2012), Kou et al (2015), Horká et al (2016), and Chow et al (2021) did not comprise the entire generic and species diversity of these two clades known at that time and new species have been discovered since (e.g., De Gier & Fransen, 2018;Anker & De Grave, 2021;Fransen et al, 2021). It is hypothesized that the number of host switches is underestimated due to the limited number of taxa included in previous analyses.…”

“…In this study, we extended the molecular alignment and included a morphological dataset, similar to those of Fransen (2002) and De Gier & Fransen (2018), to include all species that are hypothesized to be part of the aforementioned clade 6 from Horká et al (2016) (table 1). Our assemblage of genera thus consisted of Anchiopontonia Bruce, 1992, Bruceonia Fransen, 2002, Cainonia Bruce, 2005, Conchodytes Peters, 1852, Pinnotherotonia Marin & Paulay, 2010, Platypontonia Bruce, 1968, and Pseudopontonia Bruce, 1992, which are associated with bivalve molluscs, and the genera Ascidonia Fransen, 2002, Colemonia Bruce, 2005, Dactylonia Fransen, 2002, Notopontonia Bruce, 1991, and Rostronia Fransen, 2002, of which all species are associated with solitary ascidians.…”

A Review of the Ecomorphology of Pinnotherine Pea Crabs (Brachyura: Pinnotheridae), with an Updated List of Symbiont-Host Associations

“…The denticles, however, resemble those on the chelipeds' cutting edges mentioned above (see Section 3.3), and may be used to scrape or groom their host, or even their own bodies for gathering mucus: some species are illustrated with their last pair of ambulatory legs being folded up against the dorsal side of their carapace (e.g., A. borradailei (Nobili, 1906) [121]). In addition, the denticles might be used for chemoreception, by 'tasting' food with its ambulatory legs, as oberved in Zaops ostreum [109], or for providing grip inside the host: similar rows of scales can be found on the dactyli of the ambulatory legs of some palaemonid shrimp species, also living in bivalves and ascidians [57,58,124]. Furthermore, all members of the gastropod-associated Calypraeotheres, except C. garthi, also possess sword-like, setose dactyli on their last ambulatory legs [89,[125][126][127][128].…”