Donato Marino

TOWARD AN ASSESSMENT ON THE TAXONOMY OF DINOFLAGELLATES THAT PRODUCE CALCAREOUS CYSTS (CALCIODINELLOIDEAE, DINOPHYCEAE): A MORPHOLOGICAL AND MOLECULAR APPROACH

In recent years an unified classification system for both fossil cysts and extant dinoflagellate species has been proposed. This classification has prompted investigations aimed at testing the phylogenetic validity of the distinctive morphological characters of both vegetative cells and cysts. We have focused on a group of dinoflagellates that produce calcareous resting cysts, which are abundant in marine neritic and oceanic waters and form wide fossil deposits. Extant species are included in the genera Scrippsiella, Ensiculifera, and “Pentapharsodinium” (subfamily Calciodinelloideae), which are distinguished by the number and/or shape of the cingular plates of their planktonic vegetative stages. On the other hand, the classification of fossil cysts is based on the morphology of the calcareous covering and on the orientation of crystals. In this study we combine the information derived from morphological traits of both motile stages and cysts with that obtained from nucleotide sequence analysis of the ribosomal DNA internal transcribed spacers (ITS). We also describe the vegetative cell produced by the calcareous cyst Calcigonellum infula and a new variety, Scrippsiella trochoidea var. aciculifera var. nov. Molecular analyses confirm the monophyletic origin of the genus Scrippsiella, whereas the “Pentapharsodinium” and Ensiculifera species are grouped together in another monophyletic cluster. The coupled morphological and molecular approach supports the taxonomic value of some of the characters of the planktonic stage, such as the cingular plate number. On the other hand, it questions the validity of other morphological characters of both vegetative and encysted stages. Our data provide a phylogenetic classification of these dinoflagellates; however, they also open a debate that would imply a redefinition of the characters to be used for the circumscription of the subfamily Calciodinelloideae.

Marine taxa of Cocconeis on leaves of Posidonia oceanica , including a new species and two new varieties

Eight Cocconeis Ehrenberg taxa (species and varieties) epiphytic on the leaves of Posidonia oceanica (L.) Delile were studied by scanning and transmission electron microscopy. Samples of Posidonia oceanica were collected throughout the year from seagrass meadows around the island of Ischia (Gulf of Naples, Italy). On the basis of some peculiar ultrastructural characteristics of the valve areolation, a new species, Cocconeis multiperforata sp. nov., and two new varieties, C. neothumensis var. marina var. nov., and C. scutellum var. posidoniae var. nov., are described. Ultrastructural analysis also revealed new morphological characteristics in C. britannica Naegeli in Ku

Calcareous dinoflagellate cysts in marine sediments of the Gulf of Naples (Mediterranean Sea)

tzing and C. maxima (Grunow) Peragallo & Peragallo, and confirmed observations of other authors for C. molesta var. crucifera Grunow, C. pellucida Grunow in Rabenhorst and C. stauroneiformis (Rabenhorst) Okuno. Our observations on the abundance of the different species provide new information on their distribution and ecology.

Morphological variability of the potentially toxic dinoflagellate Dinophysis sacculus (Dinophyceae) and its taxonomic relationships with D. pavillardii and D. acuminata

Abstract Ten different calcareous cyst morphotypes were found in surface sediments of the Gulf of Naples. For four of them [Scrippsiella trochoidea (Stein) Loeblich III, S. precaria Montresor and Zingone, S. lachrymosa Lewis and Pentapharsodinium tyrrhenicum (Balech) Montresor, Zingone and Marino] the cyst-theca relationship was confirmed by germination experiments. These cysts constituted a large fraction (27–79%) of the entire dinoflagellate cyst assemblage of the Gulf of Naples and were particularly abundant at station s close to the coast. Calcareous cyst populations were characterized by a species composition which differed from other coastal areas so far investigated. The relative abundance of cysts until now only reported from fossil records (Calcicarpinum bivalvum Versteegh, which is the paleontologic name for the cyst of Pentapharsodinium tyrrhenicum), or as rare in Recent sediments (e.g. Bicarinellum tricarinelloides Versteegh, Follisdinellum splendidum Versteegh), appears to be a peculiar character of the cyst assemblage in the Gulf of Naples.

THE CALCAREOUS RESTING CYST OF PENTAPHARSODINIUM TYRRHENICUM COMB. NOV. (DINOPHYCEAE)1

The identity of Dinophysis sacculus Stein has proved to be problematic in recent years, during which this species has been associated with diarrhoetic shellfish poisoning (DSP) events along European coasts. To complement the scarce and at times contradictory existing information, we provide details of morphological variation in D. sacculus throughout its geographical range, which includes the Mediterranean Sea and European Atlantic coasts. Our data clarify its relationship with D. pavillardii Schroder. This species differs from D. sacculus only by the presence of a concavity along the dorsal margin, but transitional morphotypes are frequent in almost all the samples examined. We therefore propose merging the two species and classifying morphotypes with a dorsal concavity as D. sacculus f. reniformis (Pavillard) comb. nov. Despite the high variability of Dinophysis sacculus, it was generally possible to separate it from D. acuminata Claparede & Lachmann. The only character distinguishing the two species is...

Morphology and taxonomy of Amphicocconeis gen. nov. (Achnanthales, Bacillariophyceae, Bacillariophyta) with considerations on its relationship to other monoraphid diatom genera

While investigating dinoflagellate cyst assemblages in surface sediments of the Gulfs of Naples and Salerno (Mediterranean Sea), we found a new calcareous resting cyst. This cyst has a round to oval body surrounded by a thick mineral layer, which gives it the shape of a Napoleon hat, with a flat, oval face bearing the archeopyle and a convex keel on the opposite side. The cyst shape is variable in both natural samples and clonal cultures. The organic membrane underlying the calcareous covering is resistant to acetolysis, thus demonstrating the presence of sporopolleninlike material. The cyst germinated into a motile stage having the same morphological features and thecal plate pattern as Peridinium tyrrhenicum Balech. We believe the validity of the genus Pentapharsodinium Indelicato & Loeblich should be accepted. Based on the comparative examination of the species we collected and of a similar species, Pentapharsodinium trachodium Indelicato & Loeblich, we propose Pentapharsodinium tyrrhenicum as a new combination for Peridinium tyrrhenicum.

AN ELECTRON MICROSCOPE INVESTIGATION ON CHAETOCEROS MINIMUS (LEVANDER) COMB. NOV. AND NEW OBSERVATIONS ON CHAETOCEROS THRONDSENII (MARINO, MONTRESOR AND ZINGONE) COMB. NOV.

SEM and TEM observations on the cleaned material used by Hustedt for the preparation of the type of the marine diatom Cocconeis disculoides Hustedt and on living specimens of the species scraped from Posidonia oceanica (L.) Delile leaves collected in different coastal areas of the Mediterranean Sea revealed structures that differentiate this species from the genus Cocconeis Ehrenberg. The external apical raphe endings have marked terminal fissures; valvocopulae extend over a large part, or all, of the valve surface and bear rounded perforations arranged differently in the two bands; areolae are occluded by simple hymenes with irregularly distributed, rounded perforations. Recently, C. disculoides Hustedt was transferred to Psammococconeis Garcia, a new genus found in sediment samples from Port Belo Peninsula (Brazil), as P. disculoides (Hustedt) Garcia. However, the genus Psammococconeis lacks the raphe terminal fissures, shows two types of areolae in the sternum valve mantle and an extended valvocopula with perforations only in the raphid valve. Furthermore, in P. disculoides, the areolae are occluded by fimbriate hymenes in both valves. These observations lead us to propose the new genus Amphicocconeis, which at present includes only A. disculoides (Hustedt) comb. nov. The elements of Hustedts type material examined by Garcia should be the lectotype of a new species of Psammococconeis.

MORPHOLOGY OF THE DIATOM GENUS CAMPYLONEIS (BACILLARIOPHYCEAE, BACILLARIOPHYTA), WITH A DESCRIPTION OF CAMPYLONEIS JULIAE SP. NOV. AND AN EVALUATION OF THE FUNCTION OF THE VALVOCOPULAE1

The fine structure of vegetative cells and resting spores of Rhizosolenia minima Levander from three Tyrrhenian brackish-water lagoons has been investigated by electron microscopy. The species has none of the morphological characters typical of the genus Rhizosolenia Ehrenberg and appears to be closely related to Miraltia throndsenii Marino, Montresor & Zingone which belongs to the family Chaetoceraceae (sensu Simonsen 1979) or Chaetocerataceae (sensu Round et al. 1990). In a few natural samples from the Gulf of Naples, a new variety of the latter species possessing three setae has been found, co-occurring with the already described morphotype. Therefore, both varieties are transforred to the genus Chaetoceros Ehrenberg (sub-genus Hyalochaete) as C. throndsenii var. throndsenia (Marino, Montresor & Zingone) Marino, Montresor & Zingone comb. nov. and C. throndsenii var. trisetosa Zingone var. nov. Based on the fine morphology and the occasional presence of a third seta (van Goor 1924) the inclusion of Rhiz...

Miraltia throndsenii gen. nov., sp. nov., a planktonic diatom from the Gulf of Naples

A revision of the monoraphid pennate diatom genus Campyloneis Grunow was carried out based on LM and EM observations. The material examined originated from various herbarium collections and from extant epiphytic diatom communities on leaves of Posidonia spp. We also examined the generitype C. grevillei (Smith) Grunow and the fossil material of C. gheyselinchi Reinhold from which the author extracted the type. Our results clarified the fine structure of C. grevillei and C. gheyselinchi. Of the various varieties of C. grevillei, only the variety argus (Grunow) Cleve was retained. This differs from the nominate variety in the arrangement and shape of the areolae adjacent to the sternum of the araphid valve. The newly described taxon Campyloneis juliae De Stefano differs from all Campyloneis species in areolae ultrastructure and morphology of the valvocopulae. As for the fossil species C. gheyselinchi, the sternum valve areolae are similar to those of C. grevillei, but scarcity of frustules in the type material prohibited evaluation of its variability. For this reason we provisionally maintained its rank of species. The elaborate linking systems among the valvocopulae and valves in Campyloneis species appear to provide structural reinforcement against pressure from neighboring epiphytic diatoms and scouring of seagrass leaves.

Comparison of Cocconeis pseudonotata sp. nov. with two closely related species, C. notata and C. diruptoides, from Posidonia oceanica leaves

Miraltia throndsenii gen.nov., sp.nov., a small centric diatom from Gulf of Naples coastal waters, is described. The ultrastructural features of the species are very similar to those reported for the family Chaetoceraceae. However, a new generic name is proposed due to the presence of a single seta per valve. A description of the resting spores, presumably formed within auxospores, is also given. The phylogenetic position of the new genus within the family Chaetoceraceae is discussed.