Islandinium pacificum sp. nov., a new dinoflagellate cyst from the upper Quaternary of the northeast Pacific

Round brown process-bearing cysts (RBPC) produced by dinoflagellates (Dinophyceae) occur as an important part of assemblage diversities in seafloor sediments worldwide. Here a new species, Islandinium pacificum, is described from surface sediment samples from coastal waters of British Columbia (Canada). Additional observations are made on material from the Holocene of Kyuquot Sound (Vancouver Island, Canada) and the Eemian of the Voring Plateau (North Atlantic). The cysts have a smooth wall and bear acuminate processes with barbs. Incubation experiments reveal an affinity with the motile stage Protoperidinium mutsuense. The ecology of the new species is specified

Hiddenocysta matsuokae gen. nov. et sp. nov. from the Holocene of Vancouver Island, British Columbia, Canada

A new dinoflagellate cyst genus and species are described here as Hiddenocysta gen. nov. and Hiddenocysta matsuokae sp. nov. from Holocene sediments in a core from the west coast of Vancouver Island (British Columbia, Canada). The genus Hiddenocysta encompasses spherical to ovoid skolochorate cysts, characterized by a gonyaulacoid plate pattern and a 2P precingular archeopyle. The species H. matsuokae is characterized by a granular wall and slender trifurcate processes with heavily perforated process bases. Two end members are described here based on process morphology and number of processes (formas 1 and 2). Cyst wall chemistry is analyzed using micro-Fourier transform infrared (FTIR) spectroscopy and reveals a unique dinosporin composition consistent with a gonyaulacoid autotrophic feeding strategy

Adaptive divergence in shell morphology in an ongoing gastropod radiation from Lake Malawi

Background Ecological speciation is a prominent mechanism of diversification but in many evolutionary radiations, particularly in invertebrates, it remains unclear whether supposedly critical ecological traits drove or facilitated diversification. As a result, we lack accurate knowledge on the drivers of diversification for most evolutionary radiations along the tree of life. Freshwater mollusks present an enigmatic example: Putatively adaptive radiations are being described in various families, typically from long-lived lakes, whereas other taxa represent celebrated model systems in the study of ecophenotypic plasticity. Here we examine determinants of shell-shape variation in three nominal species of an ongoing ampullariid radiation in the Malawi Basin (Lanistes nyassanus, L. solidus and Lanistes sp. (ovum-like)) with a common garden experiment and semi-landmark morphometrics. Results We found significant differences in survival and fecundity among these species in contrasting habitats. Morphological differences observed in the wild persisted in our experiments for L. nyassanus versus L. solidus and L. sp. (ovum-like), but differences between L. solidus and L. sp. (ovum-like) disappeared and re-emerged in the F-1 and F-2 generations, respectively. These results indicate that plasticity occurred, but that it is not solely responsible for the observed differences. Our experiments provide the first unambiguous evidence for genetic divergence in shell morphology in an ongoing freshwater gastropod radiation in association with marked fitness differences among species under controlled habitat conditions. Conclusions Our results indicate that differences in shell morphology among Lanistes species occupying different habitats have an adaptive value. These results also facilitate an accurate reinterpretation of morphological variation in fossil Lanistes radiations, and thus macroevolutionary dynamics. Finally, our work testifies that the shells of freshwater gastropods may retain signatures of adaptation at low taxonomic levels, beyond representing an evolutionary novelty responsible for much of the diversity and disparity in mollusks altogether

Taxonomic re-examination of the toxic armored dinoflagellate Pyrodinium bahamense Plate 1906: Can morphology or LSU sequencing separate P. bahamense var. compressum from var. bahamense?

Pyrodinium bahamense Plate 1906 is a tropical to subtropical dinoflagellate that can cause paralytic shellfish poisoning (PSP). Based on differences in the morphology of the motile stage, as well as geographic distribution, this species was separated into two varieties, the toxic var. compressum and the non-toxic var. bahamense by Steidinger et al. (1980). Thereafter, Balech (1985) carefully reinvestigated the two varieties and concluded there were no significant morphological differences between them. We re-examined the motile cell and cyst morphology of these two varieties, concurring with the arrangement of the sulcal plates, but demonstrating the plate overlap for the first time. The observed size-frequency spectra of cell body diameter, cyst body diameter and cyst process length were unimodal. Overall, we agree with Balech (1985) that there is no consistent criterion to unequivocally separate both varieties based on morphology. We therefore recommend ceasing the use of these varieties (and forma). In addition, we suggest that observations of both varieties in a single plankton sample should be interpreted as the occurrence of different life stages at the sampling time. However, the phylogenetic analysis using partial LSU rDNA sequence data revealed two clearly separated ribotypes within the Pyrodinium clade, an Indo-Pacific and Atlantic-Caribbean ribotype, suggesting that Pyrodinium bahamense is a species complex. The genetic distance between these ribotypes is short, which suggests a late Quaternary separation. Geochemical analyses of the cyst walls also show differences between specimens from both geographical regions.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/harmful-algae/,The publisher has made available a Corrigendum for Figure 3. It can be found in Harmful Algae, Vol. 42, February 2015, Pages 71-72. doi:10.1016/j.hal.2014.12.002. It may also be viewed here as a secondary "Corrigendum" file.Keywords: Saxitoxins, LSU, Biometry, Theca, Thermophile, Cys

The dinoflagellate cyst genera Achomosphaera Evitt 1963 and Spiniferites Mantell 1850 in Pliocene to modern sediments: a summary of round table discussions

Source at https://doi.org/10.1080/01916122.2018.1465739. We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al.1973) Londeix et al. 2009, Spiniferites? rubinus (Rossignol 1962 ex Rossignol 1964) Sarjeant 1970, and Thalassiphora balcanica Baltes ̧ 1971. This summary forms the basis for a set of papers that follows, where points raised during the workshops are explored in greater detail