Out of taxonomic crypsis: A new trans-arctic cryptic species pair corroborated by phylogenetics and molecular evidence.

Cryptic species are a common phenomenon in cosmopolitan marine species. The use of molecular tools has often uncovered cryptic species occupying a fraction of the geographic range of the original morphospecies. Shipworms (Teredinidae) are marine bivalves, living in drift and fixed wood, many of which have a conserved morphology across cosmopolitan distributions. Herein novel and GenBank mitochondrial (cytochrome c oxidase subunit I) and nuclear (18S rRNA) DNA sequences are employed to produce a phylogeny of the Teredinidae and delimit a cryptic species pair in the Psiloteredo megotara complex. The anatomy, biogeography, and ecology of P. megotara, Psiloteredo sp. and Nototeredo edax are compared based on private and historic museum collections and a thorough literature review. Morphological and anatomical characters of P. megotara from the North Atlantic and Psiloteredo sp. from Japan were morphologically indistinguishable, and differ in pallet architecture and soft tissue anatomy from N. edax. The two Psiloteredo species were then delimited as genetically distinct species using four molecular-based methods. Consequently, the Northwest Pacific species, Psiloteredo pentagonalis, first synonymized with N. edax and then with P. megotara, is resurrected. Nototeredo edax, P. megotara and P. pentagonalis are redescribed based upon morphological and molecular characters. Phylogenetic analysis further revealed cryptic species complexes within the cosmopolitan species Bankia carinata and possibly additional cryptic lineages within the cosmopolitan Lyrodus pedicellatus.

Mate competition during pseudocopulation in shipworms.

Shipworms are predominantly wood-eating bivalves that play fundamental roles in biodegradation, niche creation and nutrient cycling across a range of marine ecosystems. Shipworms remain confined to the wood they colonize as larvae; however, continual feeding and rapid growth to large sizes degrade both food source and habitat. This unique lifestyle has led to the evolution of a stunning diversity of reproductive strategies, from broadcast spawning to spermcasting, larval brooding and extreme sexual size dimorphism with male dwarfism. Some species also engage in pseudocopulation, a form of direct fertilization where groups of neighbouring individuals simultaneously inseminate one another via their siphons-the only part of the animal extending beyond the burrow. Among the Bivalvia, this exceptionally rare behaviour is unique to shipworms and remains infrequently observed and poorly understood. Herein, we document pseudocopulation with video footage in the giant feathery shipworm (Bankia setacea) and novel competitive behaviours, including siphon wrestling, mate guarding and the removal of a rival's spermatozoa from the siphons of a recipient. As successful sperm transfer is likely greater for larger individuals with longer siphons, we suggest that these competitive behaviours are a factor selecting for rapid growth and large size in species that engage in pseudocopulation.

A Rhizocephalan Parasite Induces Pervasive Effects on Its Shrimp Host.

AbstractRhizocephalan barnacles are parasites of crustaceans that are known for dramatic effects on hosts, including parasitic castration, feminization, molt inhibition, and the facilitation of epibiosis. Most research on rhizocephalans has focused on carcinized hosts, with relatively little research directed to shrimp hosts that may experience distinct consequences of infection. Here, we describe a high-prevalence rhizocephalan-shrimp system in which multiple host changes are associated with infection: the dock shrimp Pandalus danae infected by the rhizocephalan Sylon hippolytes. In field-collected P. danae, infection by Sylon was associated with development of female sex characters at a smaller size and greater probability of epibiosis. Standardized video observations showed that infected P. danae performed grooming activities at higher rates than uninfected shrimp, suggesting that inhibited molting rather than direct behavioral modification is a likely mechanism for higher epibiosis rates. There was no difference in the composition of grooming behavior types or in general activity between infected and uninfected shrimp. Fatty acid compositions differed with infection, but total lipid concentrations did not, suggesting that parasite-driven shifts in host resource allocation were compensated or redirected from unmeasured tissues. Our results show that Sylon alters its host's role by provisioning an epibiotic substrate and also that it influences host physiology, resulting in feminization and fatty acid shifts. This study lays the groundwork for expanding rhizocephalan-shrimp research and encourages recognition of oft-ignored roles of parasitism in ecological communities.

Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography.

The 2011 East Japan earthquake generated a massive tsunami that launched an extraordinary transoceanic biological rafting event with no known historical precedent. We document 289 living Japanese coastal marine species from 16 phyla transported over 6 years on objects that traveled thousands of kilometers across the Pacific Ocean to the shores of North America and Hawai'i. Most of this dispersal occurred on nonbiodegradable objects, resulting in the longest documented transoceanic survival and dispersal of coastal species by rafting. Expanding shoreline infrastructure has increased global sources of plastic materials available for biotic colonization and also interacts with climate change-induced storms of increasing severity to eject debris into the oceans. In turn, increased ocean rafting may intensify species invasions.