Aggregata bathytherma sp. nov. (Apicomplexa:Aggregatidae), a new coccidian parasite associated with a deep-sea hydrothermal vent octopus.

Aggregata bathytherma sp. nov. is described from the digestive tract of Vulcanoctopus hydrothermalis, a deep-sea octopus recently discovered associated with hydrothermal vents in the northeast Pacific Ocean. Oocysts typically are spherical in shape, sometimes irregular, 163 to 356 microm in length, and 219 to 313 microm in width. Each oocyst contains from 50 to over 200 sporocysts. Sporocysts measure 27 to 32 microm in longest diameter. The cyst wall is smooth and 1 microm thick. Each sporocyst typically contains 14 to 17 sporozoites, 49 microm in length. Histological lesions associated with the presence of A. bathytherma include rupture of the basal membrane and detachment of the epithelial cells. In heavily infected areas, most of the tissue of the host digestive tract is replaced by parasites. A. bathytherma is the first Aggregata species described from a host that lives in association with hydrothermal vents, and the third species of Aggregata from eastern North Pacific waters.

Cell number and cellular composition in infusoriform larvae of dicyemid mesozoans (Phylum Dicyemida).

Cell numbers and cellular composition were examined in infusoriform larvae of 44 species of dicyemid mesozoans belonging to 6 genera; Conocyema, Dicyema, Dicyemennea, Dicyemodeca, Microcyema, and Pseudicyema. In addition, literature on infusoriform larvae of another 20 species was reviewed. Infusoriform larvae consist of a constant cell number which is species-specific. Small interspecific variations are found in total cell numbers, 35, 37, 39, 41 and 42. The most frequent cell number encountered in infusoriform larvae studied is either 37 or 39. Infusoriform larvae with 35 cells are found in three genera. Infusoriform larvae with 37 cells are found in four genera. Infusoriform larvae with 39 cells are found in four genera. Most differences in total cell numbers are due to the absence or presence of particular ventral cells. In all infusoriform larvae, the lateral, dorsal and caudal areas are cell constant, whereas in the apical and ventral areas a distinct and variable configuration of cells are present. In cellular composition, a total of 29 cells (15 cell types) were recognized in all infusoriform larvae examined. Additional cell types are characteristic of a relatively few species. Even in infusoriform larvae with the same total cell numbers, cellular composition varies by species. Thus, there are 7 variations of cellular composition in infusoriform larvae with 37 cells. Differences in larval cell numbers and types do not warrant traditional generic separation of dicyemids.

Developmental patterns and cell lineages of vermiform embryos in dicyemid mesozoans.

Patterns of cell division and cell lineages of the vermiform embryos of dicyemid mesozoans were studied in four species belonging to four genera: Conocyema polymorpha, Dicyema apalachiensis, Microcyema vespa, and Pseudicyema nakaoi. During early development, the following common features were apparent: (1) the first cell division produces prospective cells that generate the anterior peripheral region of the embryo; (2) the second cell division produces prospective cells that generate the posterior peripheral region plus the internal cells of the embryo; (3) in the lineage of prospective internal cells, several divisions ultimately result in cell death of one of the daughter cells. Early developmental processes are almost identical in the vermiform embryos of all four dicyemid genera. The cell lineages appear to be invariant among embryos and are highly conserved among species. Species-specific differences appear during later stages of embryogenesis. The number of terminal divisions determines variations in peripheral cell numbers among genera and species. Thus, the numbers of peripheral cells are fixed and hence species-specific.

New species of Dicyemennea (phylum: Dicyemida) in deep-water Graneledone (Mollusca: Cephalopoda: Octopoda) from the Antarctic.

Two new species of dicyemids are described from 2 species of deep benthic cephalopods, Graneledone antarctica and G. macrotyla, collected in the Southern Ocean south of the Antarctic Convergence. Dicyemennea bathybenthum n. sp. was found in G. antarctica. It is a medium-sized dicyemid whose length does not exceed 1,000 microm. The calotte is bluntly rounded or conical in small individuals, but the shape becomes discoidal in large individuals. Nematogens and vermiform embryos have 23 peripheral cells. An anterior abortive axial cell is present in vermiform embryos. Other stages in the life cycle were not observed. Dicyemennea dorycephalum n. sp. was found in G. macrotyla. It is a medium to large dicyemid that rarely exceeds 4,000 microm. The calotte is distinctly pointed, similar in shape to a spearhead. Vermiform stages typically have either 25 or 27 peripheral cells. An anterior abortive axial cell is present in vermiform embryos. Infusoriform embryos have 37 cells, the refringent bodies are solid in composition, and 2 nuclei are present in each urn cell.

Dicyemennea canadensis n. sp. (phylum Dicyemida) from Bathypolypus arcticus (Mollusca: Cephalopoda: Octopoda).

Dicyemennea canadensis n. sp. is described from a bathyal octopus collected off Canada in the Bay of Fundy. The dicyemid is a small species that rarely exceeds 600 microm in length. The vermiform stages are further characterized as having 17-23 peripheral cells, a conical-shaped calotte, an axial cell that extends to the base of the propoplar cells, and no abortive axial cells. Infusoriform embryos consist of 37 cells. There is 1 nucleus in each urn cell, and refringent bodies are absent. This is the first dicyemid to be described from the cephalopod Bathypolypus arcticus (Prosch. 1847), and the first dicyemid reported from Canada. In addition, it is the first species of Dicyemennea from the northwestern Atlantic Ocean to be described.

Dicyema shorti n. sp. (phylum Dicyemida) from Octopus burryi (Mollusca: Cephalopoda: Octopodidae) in the Gulf of Mexico.

Nematogens and vermiform embryos of a new species of Dicyema are described from an octopus collected off Veracruz, Mexico. Dicyema shorti n. sp. is a small dicyemid species that rarely exceeds 500 microm in length. It is further characterized by the presence of 18 peripheral cells in the vermiform stages, a conical-shape calotte, and an axial cell that extends to the base of the propolar cells. Other stages in the life cycle of the parasite are not known. This is the first dicyemid to be described from Octopus burryi Voss. 1950, and also from both the southern Gulf of Mexico and the country of Mexico.

Primer registro del pulpo 'Octopus' selene Voss, 1971 (Cephalopoda: Octopoda) en aguas peruanas con comentarios de su distribución geográfica

En el presente trabajo se registra de primera vez 'Octopus' selene en aguas peruanas y se amplía su rango de distribución sur hasta Cabo Blanco, Piura, Perú. Cuatro ejemplares machos de 34 - 50 mm LM fueron capturados entre los 03°34'S y 04°06'S a profundidades de 109 a 150 m. Se proporciona una breve descripción, con observaciones taxonómicas y comentarios sobre su distribución geográfica de esta especie.

In this paper, 'Octopus' selene is first registered in Peruvian waters and its distribution range extends south to Cabo Blanco, Piura, Peru. Four male specimens of 34 - 50 mm ML were captured between 03°34'S and 04°06'S at depths of 109 - 150 m. A brief description is provided, with taxonomic observations and comments on its geographical distribution of this species.

A new dicyemid from Octopus hubbsorum (Mollusca:Cephalopoda:Octopoda).

A new species of dicyemid mesozoan is described from Octopus hubbsorum Berry, 1953, collected in the south of Bahia de La Paz, Baja California Sur, México. Dicyema guaycurense n. sp. is a medium-size species that reaches about 1,600 µm in length. It occurs in folds of the renal appendages. The vermiform stages are characterized as having 22 peripheral cells, a conical calotte, and an axial cell that extends to the base of the propolar cells. Infusoriform embryos consist of 39 cells; 1 nucleus is present in each urn cell and the refringent bodies are solid. This is the first of a dicyemid species from a host collected in the Gulf of California.

Aggregata andresi n. sp. (Apicomplexa: Aggregatidae) from the ommastrephid squid Martialia hyadesi in the SW Atlantic Ocean and some general remarks on Aggregata spp. in cephalopod hosts.

A new species of coccidian, Aggregata andresi, is described from the digestive tract of the flying squid Martialia hyadesi, an ommastrephid squid that lives in cold subantarctic waters in the Southwest Atlantic. Gamogonic and sporogonic stages were observed in the digestive tract of 96.5% studied hosts. Oocysts were ovoid to subspheroid in shape, 170-590 microm in length and 200-530 microm in width. Each oocyst contained approximately 45,000 sporocysts. Sporocysts measured 9.5-10 microm in length and 8-8.5 microm in width. The surface of the sporocyst wall was smooth and the cyst wall thick. Each sporocyst contained three sporozoites measuring 16-20 microm in length and 2-2.5 microm width. A. andresi is the second species of Aggregata to be reported from a nerito-oceanic cephalopod host.

Marine parasites as biological tags of cephalopod hosts.

The use of marine parasites as non-intrusive natural tags of their hosts was first broadly applied in fisheries science in the 1940s. Both micro- and macroparasites have been used to assess the status of current stocks of several commercially exploited species of marine animals. Here, Santiago Pascual and Eric Hochberg offer a brief comment on marine parasite tags as a stock assessment methodology, with special reference to cephalopod hosts.

Phylogenetic relationships among cirrate octopods (Mollusca: Cephalopoda) resolved using mitochondrial 16S ribosomal DNA sequences.

PHYLOGENETIC RELATIONSHIPS AMONG THE CIRRATE OCTOPODS (MOLLUSCA: Cephalopoda) were investigated using partial sequences of the 16S rRNA mitochondrial gene. The derived phylogeny supports the traditional separation of cirrate families based on web form. Genera with a single web (Opisthoteuthis, Grimpoteuthis, Luteuthis, and Cirroctopus) are clearly distinct from those with an intermediate or secondary web (Cirroteuthis, Cirrothauma, and Stauroteuthis). The cirrates with a single web are separated into three groups. The first group is represented by Opisthoteuthis species, the second by Grimpoteuthis and Luteuthis, and the third by members of the genus Cirroctopus. There is no support for the isolation of Luteuthis in a separate family (Luteuthidae). There is, however, evidence of two groupings within the genus Opisthoteuthis. The data suggest the following revisions in the systematic classification of the cirrates: (1) Cirrothauma, Cirroteuthis, and Stauroteuthis be united in the Cirroteuthidae; (2) Grimpoteuthis and Luteuthis be placed in the Grimpoteuthidae; (3) Opisthoteuthis in the Opisthoteuthidae, and; (4) Cirroctopus be considered sufficiently distinct from both Opisthoteuthidae and Grimpoteuthidae to warrant placement in a new family.