A molecular phylogeny of Bopyroidea and Cryptoniscoidea (Crustacea: Isopoda)

Abstract

Epicaridean isopods are parasitic on other crustaceans. They represent a diverse group of highly derived taxa in two superfamilies and 10 families. Little work has been done on the phylogeny of these parasites because of the difficulty in defining homologous characters for adults above the genus level. The females exhibit morphological reduction of characters and the males have few distinguishing characters. Moreover, epicarideans have only rarely been included in past studies of isopod phylogeny. Our objective was to derive a phylogeny of epicaridean taxa based on 18S rDNA, then use that phylogeny to examine the relationships of the bopyrid subfamilies, bopyroid families and epicarideans to cymothoid isopods. We tested the monophyly of the Epicaridea, evaluated hypotheses on relationships among epicaridean families and subfamilies, examined the evolution of the abdominal mode of infestation on caridean, gebiidean, axiidean and anomuran hosts and examined coevolution between epicarideans and their crustacean hosts. The molecular phylogeny indicated that Epicaridea were monophyletic with respect to Cymothooidea. Bopyroidea formed a monophyletic group without Dajidae and Entophilinae (now as Entophilidae). Both latter taxa grouped with Cryptoniscoidea, and this group was the sister taxon to the redefined Bopyroidea in all trees. The bopyrid subfamily Ioninae is the sister taxon to the other bopyrid subfamilies (except Entophilidae). Ioninae was elevated to family status but found not to be monophyletic; a new subfamily, Keponinae, was erected for all genera formerly placed in Ioninae except the type genus. The abdominal mode of parasitism appears to have evolved independently among the subfamilies. Coevolution between host and parasite phylogenies showed extensive incongruence, indicating frequent host-switching as a general pattern in Epicaridea.http://www.zoobank.org/urn:lsid:zoobank.

Fossil Crustaceans as Parasites and Hosts

“…Dreyer and W€ agele, 2001;Boyko et al, 2013). Dreyer and W€ agele (2001, Figure 12) speculated that cirolanid-like cymothoids feeding on fish evolved to become parasitic on/in fish (Cymothoidae), and also gave rise to the Bopyridae infesting crustacean hosts, resulting in the radiation of bopyrids.…”

Supplemental Material for 'A review of bopyrids (Crustacea, Isopoda, Bopyridae) parasitic on caridean shrimps (Crustacea, Decapoda, Caridea) from China. (Bulletin of the American Museum of Natural History, no. 399)'

“…As a consequence, the monophyly of this subfamily has been questioned by earlier authors (e.g., Adkison et al, 1982;Bourdon and Bruce, 1983). Adkison et al (1982) considered Parargeia Hansen, 1897, to be closer to Pseudioninae and the other genera nearer to Bopyrinae, but the molecular phylogeny of Boyko et al (2013) Stebbing, 1893: 336, 337;Calman, 1898: 281;Richardson, 1899a: 868;Richardson, 1899b: 336-337;Bonnier, 1900: 48, 61, 171, 221, 327-328, fig. 55;Richardson, 1900: 308;Gerstaecker, 1901: 185;Richardson, 1904a: 45, 60-64, figs.…”

“…sp., is seen with Metaphrixus intutus Bruce, 1966, which is positioned over the host branchial chamber and is attached underneath a raised flange derived from the first abdominal pleuron of the host. The branchial mode of parasitism is considered to be the ancestral condition for bopyrids (see Boyko et al, 2013) and Sigyn branchialis, n. gen., n. sp., with its branchial position and full complement of pereopods on both sides of the female body may represent the most primitive hemiarthrine known to date.…”

“…Subsequently, Bopyrophryxinae Condreanu, 1965, was synonymized with Pseudioninae Codreanu, 1967 (Bourdon andBoyko, 2005). Boyko et al (2013) used 18S rDNA to explore the phylogeny of epicarideans and their results showed that Ioninae H. Milne Edwards, 1840, should be restricted to the type genus and removed from Bopyridae; the remaining species formerly in Ioninae were placed into a newly described Keponinae Boyko et al, 2013. Additionally Boyko et al (2013 showed that Entophilinae Richardson, 1903, did not belong to Bopyridae but rather was a family within Cryptoniscoidea.…”

150 million years old isopods on fishes: a possible case of palaeo-parasitism

“…Most parasitic isopods that are ectoparasites occur within five major groups: Cymothoidae, Aegidae, Bopyroidea, Cryptoniscoidea and Gnathiidae (Williams & Boyko 2012, Boyko et al 2013, which are all ingroups of Cymothoida. Representatives of Cymothoidae and Gnathiidae prefer fishes as hosts, while species of Bopyridea and Cryptoniscoidea are generally found on decapod crustaceans.…”