Charles J. O'Kelly

OBSERVATIONS ON MARINE CHAETOPHORACEAE (CHLOROPHYTA). I. SPORANGIAL ONTOGENY IN THE TYPE SPECIES OF ENTOCLADIA AND PHAEOPHILA1

A light‐ and electron‐microscope study of sporangial ontogeny in synchronized, mitospore‐producing cultures of Entocladia viridis Reinke, and Phaeophila dendroides (Crouan frat.) Ratters demonstrates that each species has its own characteristic pattern of sporangial development. E. viridis undergoes a sequential cleavage of sporangial mother cell contents with cytokinesis always promptly following mitosis, thus no multinucleate cells are produced. No vesicle surrounds the mature spores, which are released by abrupt rupture of the exit papilla. In P. dendroides a simultaneous cleavage of the sporangial mother cell occurs after a series of synchronous mitoses that result in the production of a multinucleate cell. No vesicle surrounds the mature spores, but a membranous inclusion derived from the central vacuole of the sporangial mother cell lines the sporangial neck at maturity. The inclusion is extruded as a hyaline “plug” through the apex of the sporangial neck some time before release of the spores. This information argues for the retention of the two genera Entocladia and Phaeophila, and suggests another means of deducing higher taxonomic relationships among the marine Chaetophoraceae.

Molecular and morphological diversity of Narragansett Bay (RI, USA) Ulva (Ulvales, Chlorophyta) populations

Macroalgal bloom‐forming species occur in coastal systems worldwide. However, due to overlapping morphologies in some taxa, accurate taxonomic assessment and classification of these species can be quite challenging. We investigated the molecular and morphological characteristics of 153 specimens of bloom‐forming Ulva located in and around Narragansett Bay, RI, USA. We analyzed sequences of the nuclear internal transcribed spacer 1 region (ITS1) and the chloroplast‐encoded rbcL; based on the ITS1 data, we grouped the specimens into nine operational taxonomic units (OTUs). Eight of these OTUs have been previously reported to exist, while one is novel. Of the eight OTUs, all shared sequence identity with previously published sequences or differed by less than 1.5% sequence divergence for two molecular markers. Previously, 10 species names were reported for Ulva in Rhode Island (one blade and nine tube‐forming species) based upon morphological classification alone. Of our nine OTUs, three contained blade‐forming specimens (U. lactuca, U. compressa, U. rigida), one OTU had a blade with a tubular stipe, and six contained unbranched and/or branched tubular morphologies (one of these six, U. compressa, had both a blade and a tube morphology). While the three blade‐forming OTUs in Narragansett Bay can frequently be distinguished by careful observations of morphological characteristics, and spatial/temporal distribution, it is much more difficult to distinguish among the tube‐forming specimens based upon morphology or distribution alone. Our data support the molecular species concept for Ulva, and indicate that molecular‐based classifications of Ulva species are critical for proper species identification, and subsequent ecological assessment or mitigation of Ulva blooms.

Small doses, big troubles: Modeling growth dynamics of organisms affecting microalgal production cultures in closed photobioreactors

The destruction of mass cultures of microalgae by biological contamination of culture medium is a pervasive and expensive problem, in industry and research. A mathematical model has been formulated that attempts to explain contaminant growth dynamics in closed photobioreactors (PBRs). The model simulates an initial growth phase without PBR dilution, followed by a production phase in which culture is intermittently removed. Contaminants can be introduced at any of these stages. The model shows how exponential growth from low initial inocula can lead to explosive growth in the population of contaminants, appearing days to weeks after inoculation. Principal influences are contaminant growth rate, PBR dilution rate, and the size of initial contaminant inoculum. Predictions corresponded closely with observed behavior of two contaminants, Uronema sp. and Neoparamoeba sp., found in operating PBRs. A simple, cheap and effective protocol was developed for short-term prediction of contamination in PBRs, using microscopy and archived samples.

THE GREEN ALGAL GENUS CLONIOPHORA REPRESENTS A NOVEL LINEAGE IN THE ULVALES: A PROPOSAL FOR CLONIOPHORACEAE FAM. NOV.1

The green algal genus Cloniophora has been classified in the Chaetophorales (Chlorophyceae) based on morphological characters. This study uses DNA sequence data from the nucleus (SSU) and the chloroplast (tufA) from collections in the Hawaiian Islands and a culture originating from Portugal to test this classification. Taxonomic identities of contemporary collections were confirmed by sequencing small fragments of DNA (rbcL and SSU) from type specimens, including the generitype, Cloniophora willei L. H. Tiffany. These molecular data show that Cloniophora does not have close affinities to the Chaetophorales and belongs instead to the Ulvales (Ulvophyceae). The morphological features of eight or more reproductive products per cell and a pyrenoid with a traversing thylakoid membrane support the molecular data and confirm the placement of this group in the Ulvales. As this genus does not belong to any recognized family in the Ulvales, the family Cloniophoraceae, containing the single genus Cloniophora, is proposed.

New Ulvaceae (Ulvophyceae, Chlorophyta) from mesophotic ecosystems across the Hawaiian Archipelago

Ulvalean algae (Chlorophyta) are most commonly described from intertidal and shallow subtidal marine environments worldwide, but are less well known from mesophotic environments. Their morphological simplicity and phenotypic plasticity make accurate species determinations difficult, even at the generic level. Here, we describe the mesophotic Ulvales species composition from 13 locations across 2,300 km of the Hawaiian Archipelago. Twenty‐eight representative Ulvales specimens from 64 to 125 m depths were collected using technical diving, submersibles, and remotely operated vehicles. Morphological and molecular characters suggest that mesophotic Ulvales in Hawaiian waters form unique communities comprising four species within the genera Ulva and Umbraulva, each with discrete geographic and/or depth‐related distributional patterns. Three genetically distinct taxa are supported by both plastid (rbcL and tufA) and nuclear (ITS1) markers, and are presented here as new species: Umbraulva kaloakulau, Ulva ohiohilulu, and Ulva iliohaha. We also propose a new Umbraulva species (Umbraulva kuaweuweu), which is closely related to subtidal records from New Zealand and Australia, but not formally described. To our knowledge, these are the first marine species descriptions from Hawai‘i resulting from the collaboration of traditional Hawaiian nomenclature specialists, cultural practitioners and scientists. The difficulty of finding reliable diagnostic morphological characters for these species reflects a common problem worldwide of achieving accurate identification of ulvalean taxa using solely morphological criteria. Mesophotic Ulvales appear to be distinct from shallow‐water populations in Hawai‘i, but their degree of similarity to mesophotic floras in other locations in the Pacific remains unknown.

Diversity and Evolution of Paramoeba spp. and their Kinetoplastid Endosymbionts

Members of the genus Paramoeba (including Neoparamoeba) (Amoebozoa) are single‐celled eukaryotes of economic and ecological importance because of their association with disease in a variety of marine animals including fish, sea urchins, and lobster. Interestingly, they harbor a eukaryotic endosymbiont of kinetoplastid ancestry, Perkinsela sp. To investigate the complex relationship between Paramoeba spp. and Perkinsela sp., as well as the relationships between different Paramoeba species, molecular data was obtained for four novel isolates. We also acquired new data from the urchin pathogen P. invadens. Comprehensive molecular phylogenetic analyses were carried out using 33 newly obtained 18S rDNA sequences from the host amoebae and 16 new 18S rDNA sequences from their corresponding Perkinsela sp., together with all publicly available 18S molecular data. Intra‐isolate 18S rDNA nucleotide diversity was found to be surprisingly high within the various species of Paramoeba, but relatively low within their Perkinsela sp. endosymbionts. 18S rDNA phylogenies and ParaFit co‐evolution analysis revealed a high degree of congruence between the Paramoeba and Perkinsela sp. tree topologies, strongly suggesting that a single endosymbiotic event occurred in the common ancestor of known Paramoeba species, and that the endosymbionts have been inherited vertically ever since.

Molecular phylogeny and taxonomic revision of the genus Wittrockiella (Pithophoraceae, Cladophorales), including the descriptions of W. australis sp. nov. and W. zosterae sp. nov.

Wittrockiella is a small genus of filamentous green algae that occurs in habitats with reduced or fluctuating salinities. Many aspects of the basic biology of these algae are still unknown and the phylogenetic relationships within the genus have not been fully explored. We provide a phylogeny based on three ribosomal markers (ITS, LSU, and SSU rDNA) of the genus, including broad intraspecific sampling for W. lyallii and W. salina, recommendations for the use of existing names are made, and highlight aspects of their physiology and life cycle. Molecular data indicate that there are five species of Wittrockiella. Two new species, W. australis and W. zosterae, are described, both are endophytes. Although W. lyallii and W. salina can be identified morphologically, there are no diagnostic morphological characters to distinguish between W. amphibia, W. australis, and W. zosterae. A range of low molecular weight carbohydrates were analyzed but proved to not be taxonomically informative. The distribution range of W. salina is extended to the Northern Hemisphere as this species has been found in brackish lakes in Japan. Furthermore, it is shown that there are no grounds to recognize W. salina var. kraftii, which was described as an endemic variety from a freshwater habitat on Lord Howe Island, Australia. Culture experiments indicate that W. australis has a preference for growth in lower salinities over full seawater. For W. amphibia and W. zosterae, sexual reproduction is documented, and the split of these species is possibly attributable to polyploidization.