Richard N. Pienaar

The taxonomy of the order Isochrysidales (Prymnesiophyceae) with special reference to the genera Isochrysis Parke, Dicrateria Parke and Imantonia Reynolds

The order Isochrysidales was erected by Pascher in 1910 to accommodate chrysomonads with two equal flagella. It was based on the family Hymenomonadaceae (Senn, 1900) and included such genera as Synura Ehrenberg (later shown to be heterokont and therefore incorrectly placed here; Hovasse, 1949; Manton, 1955), Wyssotzkia Lemmermann and Hymenomonas Stein. Papenfuss (1955) used the name in a similar sense but encompassing also the coccolithophorids, while those genera with two equal flagella and a ‘short third flagellum’ ( (Prymnesium Massart, Platychrysis N. Carter, Chrysochromulina Lackey) were placed in the order Prymnesiales. Subsequently it was demonstrated that members of the Isochrysidales and Prymnesiales differ from other chrysomonads in that the two true flag-ella are smooth with no coarse hairs (‘mastigonemes’) and that the third appendage found in genera of the latter order is a unique structure, termed the ‘haptonema’ by Parke, Manton & Clarke (1955). On the basis of these observations, Christensen (1962) erected a new class, the Haptophyceae (now referred to by the typified name Prymnesiophyceae; Hibberd, 1976 a), to contain the two orders although Bourrelly (1968) preferred to retain them within the Chrysophyceae whilst recognizing their unique status by the erection of a sub-class, the Isochrysophycidae.

Ultrastructure of a new marine sand-dwelling dinoflagellate, Gymnodinium quadrilobatum sp. nov. (Dinophyceae) with special reference to its endosymbiotic alga

A new sand-dwelling dinoflagellate, Gymnodium quadrilobatum sp. nov., is described from the south coast of Natal, South Africa. The organism contains 20–30 chloroplasts, which are peripherally arranged, and a conspicuous eyespot. The motile cell is directly transformed into a non-motile cell and cell division is restricted to the non-motile phase. The motile cell has a typical gymnodinioid organisation, while the non-motile cell possesses a thick cell wall and develops the characteristic cell shape, which is reminiscent of a four-leaved clover. The chloroplasts of G. quadrilobatum belong to an endosymbiotic alga the cytoplasm of which is separated from the host (dinoflagellate) cytoplasm by a single unit membrane. Other organelles contained in the endosymbiont cytoplasm are the nucleus, ribosomes and mitochondria. The endosymbiont is thought to be a chromophyte alga. The eyespot is bounded by a triple membrane and is situated in the host cytoplasm. On the basis of the similarities in the ultrastructure of...

Brown tides and mariculture in Saldanha Bay, South Africa.

In 1997, the brown tide organism, Aureococcus anophageffens, was detected for the first time in Saldanha Bay, South Africa. Its presence was limited to an isolated, tidal dam that was similarly impacted during the late summer of the following two years but not in 2000. Bloom concentrations are typically of the order of 10(-9) cells l-1. This is one of the few reported occurrences of these nuisance blooms outside the north-eastern United States. A small oyster grow-out facility based in the dam has been severely affected by the reduced growth of oysters during these blooms. Reduced flushing of this culture site is a possible explanation for bloom initiation and persistence. However, Aureococcus blooms can be considerably more extensive as was evident during 1998 when the whole of the bay system, including Langebaan Lagoon, was affected for 6-8 weeks during late summer.

Light and electron microscope observations of the type species of Syracosphaera, s. pulchra (Prymnesiophyceae)

Syracosphaera pulchra, the type species of the genus was isolated into unialgal culture and studied with both the light and electron microscope. A conspicuous coiling haptonema is present containing seven microtubules in the shaft and eight in the basal region; features shared with many taxa in the order Prymnesiales. The proximal and distal coccoliths differ in shape but resemble each other structurally: the outer elements alternate to make the rim. The proximal coccoliths possess an organic base-plate scale which is absent in the distal coccoliths. The uncalcified organic scales are ornamented by a radial, more or less concentric, fibrillar pattern and are arranged in several layers between the proximal coccoliths and the plasmalemma. The ultrastructure of the cell is typical of prymnesiophycean algae. The flagellar apparatus is characterized by the absence of secondary microtubular bundles which are usually well developed in other coccolithophorids with two microtubular roots. This feature is also rath...

Description of a new dinoflagellate with a diatom endosymbiont, Durinskia capensis sp. nov. (Peridiniales, Dinophyceae) from South Africa

A new dinoflagellate Durinskia capensis Pienaar, Sakai et Horiguchi sp. nov. (Peridiniales, Dinophyceae), from tidal pools along the west coast of the Cape Peninsula, Republic of South Africa, is described. The dinoflagellate produces characteristic dense orange–red colored blooms in tidal pools. The organism is characterized by having a eukaryotic endosymbiotic alga. Ultrastructure study revealed the organism has a cellular construction similar to that of other diatom-harboring dinoflagellates. The cell is thecate and the plate formula is: Po, x, 4′, 2a, 6″, 5c, 4s, 5″′, 2″″, which is the same as that of Durinskia baltica, the type species of the genus Durinskia.D. capensis can, however, be distinguished from D. baltica by overall cell shape, the relative size of the 1a and 2a plates, the degree of cingular displacement, and the shape of the eyespot. Our molecular analysis based on SSU rDNA revealed that D. capensis is closely allied to D. baltica, thus supporting the assignment of this new species to this genus. This Durinskia clade takes a sister position to another diatom-harboring dinoflagellate clade, which includes Kryptoperidinium foliaceum and Galeidinium rugatum. Molecular analysis based on the rbcL gene sequence and ultrastructure study revealed that the endosymbiont of D. capensis is a diatom. The SSU rDNA gene trees indicated that four species with a diatom endosymbiont formed a clade, suggesting a single endosymbiotic origin.

Ultrastructure of a new sand-dwelling dinoflagellate, Scrippsiella arenicola sp. nov.

A new dinoflagellate, Scrippsiella arenicola Horiguchi et Pienaar sp. nov., is described from tidal pools with sandy substrates along the east coast of South Africa. S. arenicola exhibits a vertical migratory rhythm which is in synchrony with the tidal cycle. It is a medium‐sized armoured dinoflagellate with many rod‐shaped chloroplasts. Thecal plate arrangement is pp, x, 4′, 3a, 7′, 6c, 5′, 2″ and 4s. The 2a and 3a plates are separated from each other. S. arenicola has several unique ultrastructural features. Electron‐dense fibres are found on the protruded part of the thecal plates, such as on the ornamental projections or extremities of the lists. In addition to the 9 + 2 axoneme, additional fibres are found in the free moving part of the longitudinal flagellum. The portion of the transverse flagellum covered by the left sulcal list possesses a dense array of mastigonemes which connect the flagellum and the cell. The flagellar pore platelets differ from ordinary thecal plates in their thickness and fibrous nature. The ultrastructure of the apical stalk and its associated structures is described. The vertical migration and mode of cell division is also described.

The microanatomy of Hymenomonas lacuna sp.nov. (Haptophyceae)

A new species of Hymenomonas Stein, Hymenomonas lacuna sp.nov. from San Juan Island, Washington, U.S.A. is described using light and electron microscope techniques. The cells normally occur in non-motile clumps growing on the sides of the culture vessel. Each cell has a body covering composed of a single layer of coccoliths of unusual construction and several layers of circular unmineralized rimless scales. Occasional small elliptical scales are sometimes found. The general cytology of the cells is discussed with special attention paid to the unusual pyrenoid and the role of the Golgi body in scale and coccolith production. The relationship of this species to H. roseola Stein is discussed.

Ultrastructure and ontogeny of a new type of eyespot in dinoflagellates

SummaryUltrastructure and ontogeny of a new type of eyespot in dinoflagellates is described. A marine tidal poolGymnodinium natalense is found to possess a highly organized eyespot whose structure is unique among dinoflagellates. The eyespot is rectangular in ventral view, C-shaped in apical view, and is located posterior to the sulcus. The eyespot is independent of the chloroplast and consists of several (typically six) layers of hemi-cylindrical walls which are concentrically arranged with narrow spacing between them. Each hemicylindrical wall is enclosed by a single unit membrane and is composed of many regularly arranged rectangular crystalline bricks. These crystalline bricks are produced in small vesicles which are formed in the invaginations of the chloroplast. The vesicles containing newly formed crystalline bricks are then transported to the sulcal area to assemble the eyespot. The crystalline bricks are arranged in a neat row within the vesicle termed “eyespot forming vesicle” (EFV), which is located near the sulcus. The hemi-cylindrical wall is constructed within the EFV. Based on the structure of the eyespot, viz. consisting of concentric multi-layered walls, the eyespot is thought to act as a quarter-wave stack antenna.

Possible introduction of alien phytoplankton via shipping ballast water: A South African perspective

Saldanha Bay is one of a few sites along the South African coast that is suitable for both shipping and mariculture. Ships visiting Saldanha Bay carry ballast water which, although essential, has been implicated in the transport of alien organisms. This study investigates the possible introduction of alien phytoplankton into Saldanha Bay by ballast water. The phytoplankton composition of Saldanha Bay was determined by collecting seasonal samples. Most of the 173 taxa encountered belonged to the Bacillariophyta (diatoms) and Dinophyta (dinoflagellates). The greatest species diversity in the water column was encountered during summer and autumn, but the greatest diversity of encysted organisms in the bottom sediment was encountered during winter. A catalogue of all organisms encountered was prepared to serve as a baseline for future investigations in the area. Ballast water samples, collected from 36 ships, were dominated by diatoms (64 species). Only 9 cosmopolitan species were found to be common to both the ballast waters and Saldanha Bay samples implying that the ballast water discharged into the area is not introducing any foreign organisms capable of establishing new populations. To obtain a more accurate assessment of this threat to South Africa, the methods of sampling ballast waters needs to be re-examined. Other ports also need to be investigated, especially Richards Bay, South Africa’s busiest port. Ballast water introductions of phytoplankton, seaweeds or animals into this species rich area could have damaging ecological and economic consequences.

Marine Cyanophytes from the Western Cape, South Africa: Oscillatoriales

The survey of the marine Oscillatoriales (Cyanophyceae) from the Western Cape, South Africa led to the identification of forty seven taxa. Thirty one of these are new records for South Africa; seven at the generic level ( Ammatoidea, Arthospira, Blennothrix, Havrela, Jaaginema, Komvophoron and Leibleiniae ), twenty three at the specific level ( Ammatoidea normannii, Arthrospira platensis var. non-constricta, Blennothrix lyngbyacea, Havrela mirabilis, Hydrocoleum coccineum, Jaaginema pseudogeminatum var. unigranulata, Komvophoron crassum, Leibleiniae polysiplzoniae, Limnothrix redekei, Lyngbya cf. margaretheana, Oscillatoria curviceps, O. cf. jenensis, Phormidium cf. cortianum, P. cf. dimorphum, P. cf. jenkelianum, P. laetevirens, P. persicinum, P. cf. subcapitatum, P cf. subuliforme Plectonema golenkinianum, P , cf. puteale, P. terebrans and Spirulina tenerrima ) and one variety ( Oscillatoria subbrevis f. maior ). A variety of substrata were collected along the coast in the study area and most of the cyanophytes studied and described here were found growing on rocks, sand and concrete walls. One endolithic species of cyanophyte is referred to the region.