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Fifty years ago, it was reported that individuals of the Pacific boreal limpet Problacmaea (= Erginus) bear a penis for copulation and brood their young in the pallial cavity. These observations were based on light microscopy, but now we reveal new details of the reproductive biology of Erginus (Problacmaea) puniceus with electron microscopy. Gametogenesis is fundamentally similar to other Patellogastropoda, but there are some key differences. Oocytes develop in the ovary, dorsal to the foot in the posterior half of the body, before passing through the oviduct to the pallial cavity, where they are fertilized and brooded. Development is direct with embryos being brooded to the crawl-away juvenile stage. However, sometimes fertilization occurs internally with embryos beginning development in or near the gonad. Free sperm, which were likely autosperm (self) but could have been allosperm (cross), were found near developing oocytes in the gonad. Spermiogenesis results in the formation of an enta-quasperm with a cap-like acrosome, a bullet-shaped nucleus and spherical mitochondria in the midpiece. Copulation was not observed, but we confirm the presence of a penis with a dorsal penial groove that lies below the right cephalic tentacle in males, which is typical of functional penises of some molluscs. Males were always smaller, but intermediate-sized individuals were hermaphroditic to different extents. The largest individuals were entirely female, and their penises were smaller and often lacked the penial groove. Thus, E. (Problacmaea) puniceus appears to be a protandrous hermaphrodite, passing from male to female phase. Remnants of the testis persist into the female phase, suggesting that they are protandrous hermaphrodites with overlap, possibly allowing for self-fertilization to occur on occasion. However, the largest females lacked any testis remnants, suggesting instead that the species may be protandrous sequential hermaphrodites. [ABSTRACT FROM AUTHOR]

An extensive community of organisms inhabits the common periwinkle, Littorina littorea (L., 1758), along the waveswept rocky shores of Canada's East coast. This community, which includes both facultative and obligate endosymbionts, comprises a diverse array of species from seven animal phyla, including Annelida, Arthropoda, Gnathostomulida, Nematoda, Nemertea, and Platyhelminthes, as well as ciliates and algae. The presence of larger numbers of endosymbionts was found to correlate with specific shell characteristics of the snail host, including a wider aperture and columella, suggesting that these individuals have a larger mantle cavity relative to snails housing a small community of endosymbionts. Snails with large communities of endosymbionts were usually encrusted with coralline algae and often had trematode infections. Although L. littorea has been extensively studied since the last century, the existence of this community of organisms has passed unnoticed. The large diversity of organisms in this community suggests that these snails may provide refugia for a wide range of smaller taxa. Key words: endosymbiosis, parasitism, commensalism, Mollusca, Littorinidae. Resume : Une vaste communaute d'organismes vit dans le bigorneau Littorina littorea (L., 1758) le long des cotes balayees par les vagues de la cote est du Canada. Cette communaute, qui compte des endosymbiotes facultatifs et obligatoires, comprend un eventail varie d'especes appartenant a sept phylums animaux, dont des annelides, des arthropodes, des gnathostomulides, des nematodes, des nemertes et des plathelminthes, en plus de cilies et d'algues. La presence d'un grand nombre d'endosymbiotes est correlee a certaines caracteristiques de la coquille des mollusques hotes, dont une ouverture et une columelle relativement larges, indiquant possiblement de plus grandes cavites du manteau que celles d'individus abritant de plus petites communautes d'endosymbiotes. Les bigorneaux contenant d'importantes communautes d'endosymbiotes etaient generalement incrustes d'algues corallines et presentaient des infections a trematodes. Bien que L. littorea ait fait l'objet de nombreuses etudes depuis le siecle dernier, l'existence de cette communaute d'organismes n'avait pas ete decelee auparavant. La grande diversite des organismes qui la constituent suggere que ces bigorneaux pourraient servir de refuge a un vaste eventail de petits taxons. [Traduit par la Redaction] Mots-cles: endosymbiose, parasitisme, commensalisme, mollusques, littorinides., Introduction The term symbiosis, first coined by De Bary in 1879 (cited in Vega et al. 2006) to include parasitism, as well as commensalism and mutualism, also includes epibiosis and [...]

Eusperm and parasperm ultrastructure have been studied for the first time in the neogastropod Plicopurpura patula. Eusperm structure is typical of many Neogastropoda, in which an apical bleb characterizes the conical acrosome with subacrosomal granule; the nucleus is tubular and penetrated to its tip by basal body and axoneme; the mid-piece comprises spiral mitochondria that ensheath the axoneme but terminate at the annulus, defining the junction with the end-piece. In the proximal portion of the end-piece dense tracts of glycogen match the axoneme but these disappear distally. The parasperm is unusual in having no axonemes and no motility was observed. Eusperm do not attach to parasperm, as occurs in the similar nurse cells of Littorinimorpha, thus potential functions may be limited to some form of paternity assurance as occurs in some insects. The nucleus of the parasperm is eliminated during paraspermiogenesis, but there is considerable post-transcriptional secretion activity resulting in the production of a variety of granules, some rich in glycoproteins. A prominent paracrystalline rod accumulates in the centre of the parasperm also from Golgi-derived secretions. Preliminary evidence from proteomics suggests that this parasperm carries the heat shock protein HSP70 that could play a role in fertilization inside the female. [ABSTRACT FROM AUTHOR]

Abstract: The dinoflagellate Haidadinium ichthyophilum Buckland‐Nicks, Reimchen and Garbary 1997 is an ectoparasite of the spine‐deficient, three‐spine stickleback Gasterosteus aculeatus L. Reimchen 1984, a fish endemic to Rouge Lake, Haida Gwaii. Haidadinium ichthyophilum proved difficult to assign taxonomically because its morphology and complex life cycle exhibited defining characteristics of both autotrophic and heterotrophic dinoflagellates, and was tentatively assigned to the Phytodiniales. Here, we characterized a 492 bp fragment of the small subunit ribosomal RNA (SSU rRNA) from preserved H. ichthyophilum cysts. In SSU phylogeny, H. ichthyophilum branches with the fish parasites, Piscinoodinium sp., strongly supporting the inclusion of H. ichthyophilum within the Suessiales. [ABSTRACT FROM AUTHOR]

The functional morphology of the mammiliform penial glands of Littorina saxatilis has been investigated with both light and electron microscopy. These penial glands line the ventral edge of the penis and orient with the female mantle during copulation. Secretions are released from the penial glands to this interface where they probably function in adhesion. The penial gland secretions comprise heterogeneous granules as well as apocrine and mucous secretions. The heterogeneous granules are produced in separate multicellular glands arranged in a series of lobes that lie outside a thick smooth muscle layer enclosing the lumen. Each glandular lobe is surrounded by a thin layer of smooth muscle. Secretions are transported in individual cellular processes that pass through the thick smooth muscle layer and empty into the lumen. Surrounding the lumen is an epithelium containing apocrine secretory cells as well as occasional goblet-type, mucous cells. The combined action of the muscles forces secretions out of the lumen through the penial papilla, onto the external surface of the mammiliform penial gland. Longitudinal muscles extend into the penial papilla enabling its protrusion or retraction. Retraction of the penial papilla following secretion release is thought to create negative pressure beneath the penial gland producing suction adhesion. The visco-elastic properties of the penial gland secretion are qualitatively different from foot mucus and may represent specialization to an adhesive function. [ABSTRACT FROM AUTHOR]