title: A new type of brachyuran seminal receptacle in the masked crab Ethusa mascarone (Brachyura, Ethusidae).
abstract: The reproductive system of the female Ethusa mascarone was studied with a combination of histological and MRI-techniques. The study reveals a completely new type of eubrachyuran seminal receptacle. This receptacle consists of two largely separate chambers that engage with each other in a manner similar to shaking hands. One chamber facing the medial axis is lined by cuticle while the second chamber consists of a thick holocrine epithelium. Both chambers are connected by two openings of a unique structure. First, the glandular chamber opens ventro-laterally to the cuticle chamber via a laterally flattened connective duct that is lined by a highly folded cuticle. A second opening connects both chambers dorsally with the oviduct orifice. A distinct character is the cuticular hook-like projection that is situated in between the connection of oviduct opening, the glandular chamber and the cuticle chamber of the seminal receptacle. The complete seminal receptacle exhibits a combination of plesiomorphic and apomorphic characters. The arrangement of the receptacles featured in two separate chambers, including the ventro-lateral connection of the glandular chamber to the cuticle chamber, presumably reflects an early evolutionary stage of an eubrachyuran receptacle. In contrast, the dorso-lateral opening between both chambers, including the hook-like projection, appears to be an apomorphic character of at least E. mascarone. J. Morphol. 277:1497-1508, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Zoologisches Museum, Christian-Albrechts-Universität zu Kiel, Hegewischstr. 3, Kiel, 24105, Germany. shayer@zoolmuseum.uni-kiel.de.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hayer
authors.affiliation: Zoologisches Museum, Christian-Albrechts-Universität zu Kiel, Hegewischstr. 3, Kiel, 24105, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Köhnk
authors.affiliation: Functional imaging department, German Primate Center, Leibnitz Institute of Primate Research, Kellnerweg 4, Göttingen, Germany.
authors.forename: Susann
authors.initials: S
authors.lastname: Boretius
authors.affiliation: Zoologisches Museum, Christian-Albrechts-Universität zu Kiel, Hegewischstr. 3, Kiel, 24105, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Brandis
mesh_terms: D000818:Animals; D003386:Brachyura / Q000033:anatomy & histology*; D005260:Female; D005836:Genitalia, Female / Q000033:anatomy & histology*; D021621:Imaging, Three-Dimensional; D008297:Male; D010053:Ovary / Q000033:anatomy & histology; D010057:Oviducts / Q000033:anatomy & histology; D012098:Reproduction; D014621:Vagina / Q000033:anatomy & histology; D014844:Vulva / Q000033:anatomy & histology
keywords: Ethusa mascarone; histology; magnetic resonance imaging; reproductive system; seminal receptacle