title: Zachsia zenkewitschi (Teredinidae), a Rare and Unusual Seagrass Boring Bivalve Revisited and Redescribed.
abstract: The sea-grass borer Zachsia zenkewitschi belongs to a group of economically and ecologically important bivalves, commonly referred to as shipworms. The sole recognized representative of the genus Zachsia, this species displays an unusual life history and reproductive strategy that is now understood to include: environmental sex determination of free swimming larvae, extreme sexual and size dimorphism between males and females, internal fertilization, maintenance of often large harems of male dwarfs within a specialized cavity of the female mantle, and complex maternal care of larvae in specialized brood pouches within the gill. It is also the only shipworm species known to burrow in sea grass rhizomes rather than terrestrial wood. Although Z. zenkewitschi is rare and little studied, understanding of its biology and anatomy has evolved substantially, rendering some aspects of its original description inaccurate. Moreover, no existing type specimens are known for this species. In light of these facts, we designate a neotype from among specimens recently collected at the type location, and undertake a re-description of this species, accounting for recent reinterpretation of its life history and functional anatomy.
authors.affiliation: Ocean Genome Legacy, Marine Science Center, Northeastern University, Nahant, Massachusetts, United States of America.
authors.forename: J R
authors.initials: JR
authors.lastname: Shipway
authors.affiliation: Tufts Medical Centre, Boston, Massachusetts, United States of America.
authors.forename: R
authors.initials: R
authors.lastname: O'Connor
authors.affiliation: Ocean Genome Legacy, Marine Science Center, Northeastern University, Nahant, Massachusetts, United States of America.
authors.forename: D
authors.initials: D
authors.lastname: Stein
authors.affiliation: The Institute of Marine Sciences, School of Biological Sciences, University of Portsmouth, Portsmouth, P04 9LY, United Kingdom.
authors.forename: S M
authors.initials: SM
authors.lastname: Cragg
authors.affiliation: Koltzov Institute of Developmental Biology RAS, 26 Vavilov St, Moscow, 119334, Russia.
authors.forename: T
authors.initials: T
authors.lastname: Korshunova
authors.affiliation: Zoological Museum, Moscow State University, Bolshaya Nikitskaya St. 6, Moscow, 125009, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Martynov
authors.affiliation: Toyohashi Museum of Natural History, 1-238 Ôana, Ôiwa-chô, Toyohashi, Aichi, 441-3147, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Haga
authors.affiliation: Ocean Genome Legacy, Marine Science Center, Northeastern University, Nahant, Massachusetts, United States of America.
authors.forename: D L
authors.initials: DL
authors.lastname: Distel
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D017753:Ecosystem; D008018:Life Cycle Stages; D012098:Reproduction / Q000502:physiology; D012426:Russia; D012624:Seaweed / Q000502:physiology*; D013048:Specimen Handling