Christopher S. Lobban

A comparison of the physiological ecology of the seagrasses Halophila decipiens ostenfeld and H. Johnsonii eiseman from Florida

Abstract The allocation of proximate constituents in the two small seagrasses, Halophila decipiens Ostenfeld and H. johnsonii Eiseman, is similar to that reported for other seagrasses, including the concentration of soluble carbohydrate in the rhizome and roots. The photosynthesis-irradiance curves indicate that the deep water populations of H. decipiens are intolerant of irradiances above 1000 μE m−2s−1 and salinities below 35 ppt. Halophila johnsonii, an intertidal to shallow subtidal species, shows broad tolerances to higher irradiances, and to variations in salinity and temperature. The two species are compared with the larger, more widely distributed H. engelmannii Aschers.

Porpostoma guamensis n. sp., a Philasterine Scuticociliate Associated With Brown-Band Disease of Corals

ABSTRACT. Brown band disease of coral is caused by a ciliate that consumes the tissue of the corals in the genus Acropora. We describe the ciliate associated with this disease on Guam, based on: general morphology, division stages, and ciliature observed on live and protargol‐stained specimens; modification of the oral structures between divisional stages, observed on protargol‐stained specimens; and some aspects of behavior in field and laboratory studies. Porpostoma guamensis n. sp. is elongate and has ciliature typical for the genus; live cells are 70–500 × 20–75 μm; the macronucleus is sausage‐like, elongate but often bent, positioned centrally along the main cell axis; the oral ciliature follows a basic pattern, being composed of three adoral polykinetidal regions, as described for other species in the genus, although there is variability in the organization, especially in large cells where the three regions are not easily distinguished. Ciliates fed on coral with their oral region adjacent to the tissue, which they engulfed, leaving the coral a bare skeleton. Both zooxanthellae and nematocysts from coral occurred in the ciliates. Zooxanthellae appeared to be ingested alive but deteriorated within 2–3 days. Ciliates formed thin‐walled division cysts on the coral and divided up to 3 times. Cysts formed around daughter cells within cysts. We provide some observations on the complex division pattern of the ciliate (i.e. tomont–trophont–cyst) and propose a possible complete pattern that requires further validation.

A revision of the genus Cyclophora and description of Astrosyne gen. nov. (Bacillariophyta), two genera with the pyrenoids contained within pseudosepta

Ashworth M.P., Ruck E.C., Lobban C.S., Romanovicz D.K., and Theriot E.C. 2012. A revision of the genus Cyclophora and description of Astrosyne gen. nov. (Bacillariophyta), two genera with the pyrenoids contained within pseudosepta. Phycologia 51: 684–699. DOI: 10.2216/12-004.1 The araphid pennate diatom genus Cyclophora is characterized by an elliptical to circular pseudoseptum at the centre of one valve; C. tenuis is the only commonly reported species. New species have included some with pseudosepta on both valves, and we emended the generic description to accommodate these. Three species of Cyclophora were described from light and scanning electron microscopy: C. castracanei sp. nov., C. tabellariformis sp. nov. and C. minor sp. nov. Of these, C. castracanei was isovalvar with a pseudoseptum on both valves; C. tabellariformis was heterovalvar but differed in shape from the type species; and C. minor was very small and had both iso- and heterovalvar frustules. Other differences included stria density and arrangement of slits in the apical fields. Developmentally, the areolae within the boundary of the pseudoseptum filled in as the pseudoseptum grew. Also described was Astrosyne radiata gen. nov., sp. nov., which possessed a pseudoseptum in both valves but was radially symmetrical in valve outline. Transmission electron microscopy (TEM) observations of cytoplasmic ultrastructural organization and three-gene sequencing (nuclear-encoded small subunit rRNA, rbcL and psbC) of cultured cells was carried out on all except C. minor. TEM showed that pyrenoids were localized within the pseudoseptum in both Cyclophora and Astrosyne. Phylogenetic analysis of the DNA sequences also supported the close relationship between these genera. While A. radiata was not the first radially symmetrical diatom suggested to be derived from an araphid pennate lineage, the localization of pyrenoids within a central pseudoseptum in the valve may be the most distinctive synaopomorphy amongst diatoms with such different valve outlines.

Seaweed Ecology and Physiology: Light and photosynthesis

Seaweeds grow in circumstances that feature exceptionally diverse and dynamic lighting climates. The water clarity and the continual ebb and flood of tides have profound effects on the quantity and quality of the light that reaches seaweeds, adding greatly to the variation already present in the irradiance at the earths surface. The primary importance of light to seaweeds is in providing the energy for photosynthesis, energy that ultimately is passed on to other organisms. Light also has many photoperiodic and photomorphogenetic effects, as we saw in Chapter 1. Thus light is the most important abiotic factor affecting plants, and also one of the most complex. The principles of photosynthesis are similar in algae and higher plants, and indeed some principles (e.g., the Calvin cycle) were worked out using algae. Most of the catalytic proteins involved in the thylakoid reactions of red algae, for instance, are homologous with those in all other photosynthetic plants, but some are analogous (Raven et al. 1990). There are, moreover, several important features of seaweeds and their habitats that stand in sharp contrast to those in higher plants, the land plants, and it is on these that we shall focus. Such features include the diversity of pigmentation among marine algae and the diversity of the light climate in the oceans, the nature of the carbon supply in the sea, and the diversity of photosynthetic products in different algal classes.

The Giant Zooxanthellae‐Bearing Ciliate Maristentor dinoferus (Heterotrichea) is Closely Related to Folliculinidae

Abstract. The small subunit rDNA sequence of Maristentor dinoferus (Lobban, Schefter, Simpson, Pochon, Pawlowski, and Foissner, 2002) was determined and compared with sequences from other Heterotrichea and Karyorelictea. Maristentor resembles Stentor in basic morphology and had been provisionally assigned to Stentoridae. However, our phylogenetic analyses show that Maristentor is more closely related to Folliculinidae. Our results support the creation of a separate family for Maristentor, Maristentoridae n. fam., and also confirm the phylogenetic grouping of Folliculindae, Stentoridae, Blepharismidae, and Maristentoridae, which we informally call ‘stentorids’. Maristentor, rather than Stentor itself, appears to be most significant in understanding the origins of folliculinids from their aloricate ancestors. Our analyses suggest continued uncertainty in the exact placement of the root of heterotrichs with this phylogenetic marker.

Photophysics and Multifunctionality of Hypericin‐Like Pigments in Heterotrich Ciliates: A Phylogenetic Perspective

In this paper, we review the literature and present some new data to examine the occurrence and photophysics of the diverse hypericin‐like chromophores in heterotrichs, the photoresponses of the cells, the various roles of the pigments and the taxa that might be studied to advance our understanding of these pigments. Hypericin‐like chromophores are known chemically and spectrally so far only from the stentorids and Fabrea, the latter now seen to be sister to stentorids in the phylogenetic tree. For three hypericin‐like pigments, the structures are known but these probably do not account for all the colors seen in stentorids. At least eight physiological groups of Stentor exist depending on pigment color and presence/absence of zoochlorellae, and some species can be bleached, leading to many opportunities for comparison of pigment chemistry and cell behavior. Several different responses to light are exhibited among heterotrichs, sometimes by the same cell; in particular, cells with algal symbionts are photophilic in contrast to the well‐studied sciaphilous (shade‐loving) species. Hypericin‐like pigments are involved in some well‐known photophobic reactions but other pigments (rhodopsin and flavins) are also involved in photoresponses in heterotrichs and other protists. The best characterized role of hypericin‐like pigments in heterotrichs is in photoresponses and they have at least twice evolved a role as photoreceptors. However, hypericin and hypericin‐like pigments in diverse organisms more commonly serve as predator defense and the pigments are multifunctional in heterotrichs. A direct role for the pigments in UV protection is possible but evidence is equivocal. New observations are presented on a folliculinid from deep water, including physical characterization of its hypericin‐like pigment and its phylogenetic position based on SSU rRNA sequences. The photophysics of hypericin and hypericin‐like pigments is reviewed. Particular attention is given to how their excited‐state properties are modified by the environment. Dramatic changes in excited‐state behavior are observed as hypericin is moved from the homogeneous environment of organic solvents to the much more structured surroundings provided by the complexes it forms with proteins. Among these complexes, it is useful to consider the differences between environments where hypericin is not found naturally and those where it is, notably, for example, in heterotrichs. It is clear that interaction with a protein modifies the photophysics of hypericin and understanding the molecular basis of this interaction is one of the outstanding problems in elucidating the function of hypericin and hypericin‐like chromophores.

Beyond the “Code”: A Guide to the Description and Documentation of Biodiversity in Ciliated Protists (Alveolata, Ciliophora)

Recent advances in molecular technology have revolutionized research on all aspects of the biology of organisms, including ciliates, and created unprecedented opportunities for pursuing a more integrative approach to investigations of biodiversity. However, this goal is complicated by large gaps and inconsistencies that still exist in the foundation of basic information about biodiversity of ciliates. The present paper reviews issues relating to the taxonomy of ciliates and presents specific recommendations for best practice in the observation and documentation of their biodiversity. This effort stems from a workshop that explored ways to implement six Grand Challenges proposed by the International Research Coordination Network for Biodiversity of Ciliates (IRCN‐BC). As part of its commitment to strengthening the knowledge base that supports research on biodiversity of ciliates, the IRCN‐BC proposes to populate The Ciliate Guide, an online database, with biodiversity‐related data and metadata to create a resource that will facilitate accurate taxonomic identifications and promote sharing of data.

Marine necklace-chain Fragilariaceae (Bacillariophyceae) from Guam, including descriptions of Koernerella and Perideraion, genera nova

Light microscopy (LM) and scanning electron microscopy (SEM) studies of necklace‐chain forming colonial diatoms from benthic habitats in Guam revealed five species. Bleakeleya notata (Grunow in Van Heurck) Round is widespread and well‐known. Asterionella notata var. recticostata Körner has been reported only twice before; we describe the plastids for the first time. On phylogenetic grounds we assign A. notata var. recticostata to a new genus, Koernerella, and emend the description of Bleakeleya. Three new species belonging in a new genus, Perideraion, are described as P. montgomeryi, P. decipiens and P. elongatum. Cultures from single‐cell isolates yielded four gene sequences for three of these taxa. The genera are easy to identify in the LM and SEM. Perideraion differs from Bleakeleya and Koernerella in having two large H‐shaped plastids, as reported for Asterionellopsis and Asteroplanus, and is further distinguished from all these genera by the following character set: a distinct rim around the basal field of circular pores, an apical rimoportula laterally on the valve mantle, pores in the valves that are unlike those in the basal pore field, and absence of apical slits. Although the basal pole attachment and colony morphology seem synapomorphic, molecular evidence suggests that the Bleakeleya‐Koernerella‐Perideraion clade is separate from the Asterionellopsis‐Asteroplanus clade and these five genera do not form one monophyletic group. It remains to be seen whether they are part of a somewhat larger group at the base of the araphid grade or if the genera we studied are truly separate.

Licmophora flucticulata sp. nov. (Licmophoraceae, Bacillariophyceae), an unusual flabellate species from Guam and Palau

Lobban C.S., Schefter M. and Ruck E.C. 2011. Licmophora flucticulata sp. nov. (Licmophoraceae, Bacillariophyceae), an unusual new flabellate species from Guam and Palau. Phycologia 50: 11–22. DOI: 10.2216/09-85.1 A new species of Licmophora, L. flucticulata sp. nov., forms distinctive, rippled, fan-shaped colonies on coral reef seaweeds on Western Pacific islands. It is readily observed underwater with the naked eye but is very weakly silicified, and its frustule does not survive normal acid cleaning. Its identity as a Licmophora species was demonstrated with scanning electron microscopy and small-subunit rDNA sequencing. Licmophora flucticulata has exceptionally long, narrow cells cemented into fascicles that attach to the substratum by short, multistranded mucilage stalks. Its valve and colony morphology are compared to that of L. remulus, L. flabellata and L. aurivillii.

Morphological, Ultrastructural, and Molecular Characterization of Euplotidium rosati n. sp. (Ciliophora, Euplotida) from Guam

We combined morphological (i.e. live, stained, scanning, and transmission electron microscopy) with morphometric and molecular analysis to describe a ciliate species collected from shallow reefs in Guam, grown, and maintained in our laboratory. The species was recognized as a member of Euplotidium, and compared with established species of the genus: Euplotidium itoi Ito 1958; Euplotidium psammophilus (Vacelet 1961) Borror 1972; Euplotidium arenarium Magagnini and Nobili 1964; Euplotidium helgae Hartwig 1980; Euplotidium prosaltans Tuffrau 1985, and Euplotidium smalli Lei, Choi and Xu, 2002. To obtain more elements to compare the species, new morphometric data and additional SSU rRNA gene sequences of E. itoi and of E. arenarium are reported. On the basis of this comparison, we established the new species Euplotidium rosati that has a cirral pattern composed of 12 frontoventral and six transverse cirri, and lacks the left marginal cirrus. Euplotidium rosati harbors on its dorsal surface epixenosomes, the peculiar extrusive symbionts described in other Euplotidium species. The whole body of our observations together with the analysis of the data available in the literature leads us to propose a redefinition of the genus. The results may also be useful to clarify the tangled relationship between Euplotidium and Gastrocirrhus.