Diana Sarno - Academia.edu (original) (raw)

Papers by Diana Sarno

Chaetoceros wighamii Brightwell is a planktonic diatom species originally described from brackish... more Chaetoceros wighamii Brightwell is a planktonic diatom species originally described from brackish waters. Since its original description, the species has been reported in a wide variety of habitats, ranging from freshwater to marine. Varying descriptions exist in the taxonomic literature and several taxa have been considered as synonyms, including freshwater species Chaetoceros amanita. In this study we provide morphological and ultrastructural information on a cultured strain isolated from freshwater sample collected in the Lake Vrana (Vransko jezero) in Croatia, in April 2011. The cells form short and robust chains with very narrow apertures, often partially occluded by silica membranes. Other distinctive features observable in light microscopy are the shape and orientation of the setae which are very long, straight and robust, diverging in various directions from the chain axis and the single parietal chloroplast extending from valve to valve. Distinct ultrastructural characteristics are the absence of processes either in intercalary or terminal valves and the ornamentation of the valve face with densely distributed ribs spreading from an irregular eccentric hyaline area without a clearly defi ned annulus. The outer surface of the terminal valve is ornamented with small spines and setae are composed of
fl at longitudinal fi laments interconnected with short bars and ornamented with small spines tightly arranged around the setae. Our description agrees well with that reported for the freshwater morphotypes of C. wighamii (syn. C. amanita) and contributes for a reliable distinction of this intriguing taxon from similar morphotypes. This finding supports the interpretation of Chaetoceros wighamii as a freshwater/brackish species and represents the first report of a Chaetoceros species in lacustrine environment in Croatia and possibly in any Central European habitats.

Journal of Phycology, 2007

Skeletonema costatum (Grev.) Cleve emend. Zingone et Sarno and S. grevillei Sarno et Zingone were... more Skeletonema costatum (Grev.) Cleve emend. Zingone et Sarno and S. grevillei Sarno et Zingone were known only from the type material collected from Hong Kong waters more than a century ago. Both species have now been collected as live material, and their morphology and phylogenetic position are investigated in this study. Eight Skeletonema strains isolated from Florida, USA; Uruguay; and Brazil are attributed to S. costatum, while one strain from Oman is ascribed to S. grevillei based on morphological similarity to the type material of these species. In addition, a new Skeletonema species, S. ardens Sarno et Zingone, is described for a strain from Singapore and two from northern Australian waters. Skeletonema ardens has terminal fultoportula processes ending in a tapered, undulate protrusion and long intercalary fultoportulae with 1:1 junctions. The rimoportula of terminal valves is located at the margin of the valve face. No major morphological variations were observed within S. grevillei and S. ardens along a salinity gradient, whereas in S. costatum, the processes shortened and the valves came into close contact at low salinities, as already described for S. subsalsum (Cleve) Bethge. Consistent with their morphology, Skeletonema costatum and Skeletonema subsalsum also had similar rDNA sequences. Skeletonema grevillei and S. ardens were distinct in the large subunit (LSU) phylogeny. Skeletonema ardens exhibited consistent intraspecific genetic differences in both the LSU and small subunit (SSU) rDNA.

Deep-sea Research Part Ii-topical Studies in Oceanography, 2010

Sex is an obligatory event in the life cycle of many diatoms, being the means of restoration of m... more Sex is an obligatory event in the life cycle of many diatoms, being the means of restoration of maximum cell size that counteracts the progressive miniaturization induced by asexual divisions. Nonetheless, sexual stages and evidence for sexual reproduction in diatoms have rarely been directly reported from the marine environment. On September 20, 2006, different stages of the sexual cycle of two species, Pseudo-nitzschia cf. delicatissima and P. cf. calliantha, were detected in surface waters of the Gulf of Naples, at the Long Term Ecological Research Station MareChiara. The sampling date corresponded with a seasonal peak of abundance of the two species, which reached maximum concentrations of 9.1×106 and 7.0×105 cells L−1, respectively. Gametangia, auxospores of different size, and initial cells within and outside the perizonium were observed. Up to 9.2% of P. cf. delicatissima and 14.3% of P. cf. calliantha cells were undergoing sexual reproduction. The sexual event was mainly concentrated in surface waters and no sexual stages were observed a week before or after the date. The low percentage of sexual stages and the short duration of such events are probably the reasons for the scarcity of sexual stage observations in nature.

Journal of Phycology, 2005

The type material of Skeletonema costatum (Greville) Cleve was reexamined with the aims of provid... more The type material of Skeletonema costatum (Greville) Cleve was reexamined with the aims of providing an EM description of the species and clarifying which of the recently recognized Skeletonema Greville species, if any, deserves the epithet costatum. Two permanent mounts and two loose samples from the same collections from Hong Kong Bay were examined. Two distinct Skeletonema species were found in all materials. Based on the original description and on the observation of the lectotype, it was concluded that the most abundant morph in the type material is S. costatum. Cells were heavily silicified and 5–16 μm in diameter. The external processes of the fultoportulae in the terminal valves were open tubules with claw-shaped tips. The intercalary fultoportulae processes were closed flattened tubules with a pore at their base, each attached to two processes of the sibling valve (1:2 junction). The rimoportula had a long process and was located marginally in all valves. The second morph in the type material was described as Skeletonema grevillei Sarno et Zingone sp. nov. Cells were delicate, 4–7.5 μm in diameter, and formed short colonies. The fultoportulae processes in the terminal valves were open tubes having narrow tips with truncated or spiny margins. In the intercalary valves, they formed knuckle-like generally 1:1 junctions. A scallop-work of silica bridges joined the bases of the processes. The rimoportula was marginal in all valves. Neither S. costatum nor S. grevillei match any Skeletonema species that have been recently analyzed by combined morphological and molecular approaches.

Plant Biosystems, 1996

... REFERENCES CRA\VFORD RM, GARDNER C. & MEDLIN LK, 1994 - The genus Attheya. I. A desui... more ... REFERENCES CRA\VFORD RM, GARDNER C. & MEDLIN LK, 1994 - The genus Attheya. I. A desuiption offoirr new taxa, and the transfer ofGonioceros septentrionalis and G. armatus. Diatom Res. 9 27-51. ... (Ed. by CR Tomas),,pp. 5-385. Academic Press, S. Diego. ...

Aquatic Microbial Ecology, 2007

Protist, 2008

Recent studies have shown that the cosmopolitan diatom Skeletonema costatum sensu lato is compose... more Recent studies have shown that the cosmopolitan diatom Skeletonema costatum sensu lato is composed of several morphologically and genetically distinct species. To assess whether the separate species have a cosmopolitan distribution, we analysed 184 strains from marine and estuarine sites worldwide. We identified the strains using light and electron microscopy, and we sequenced the hyper-variable region of nuclear LSU rDNA. All recently described species were genetically distinct, and all but two were morphologically distinct. Variability was found for the only ultrastructural character used to distinguish Skeletonema dohrnii and S. marinoi, which cannot be identified based on morphology alone. Furthermore, multiple genetically distinct taxa, which may represent cryptic species, were found within the S. menzelii and S. tropicum clades. We found that all currently recognized species of Skeletonema are widespread, however, gaps seem to occur in their geographical ranges. For example, some species are found in both the northern and southern temperate latitudes whereas other species appear to have only subtropical to tropical ranges. Skeletonema pseudocostatum and S. grethae seem to have more restricted geographical ranges because the former was not found along American coasts and the latter was encountered only in US waters. A taxonomic update is provided for Skeletonema strains currently available in several culture collections, which could aid reinterpretation of results obtained in comparative studies using these strains.

Journal of Plankton Research, 1998

Journal of Phycology, 2005

Journal of Phycology, 2007

Chaetoceros wighamii Brightwell is a planktonic diatom species originally described from brackish... more Chaetoceros wighamii Brightwell is a planktonic diatom species originally described from brackish waters. Since its original description, the species has been reported in a wide variety of habitats, ranging from freshwater to marine. Varying descriptions exist in the taxonomic literature and several taxa have been considered as synonyms, including freshwater species Chaetoceros amanita. In this study we provide morphological and ultrastructural information on a cultured strain isolated from freshwater sample collected in the Lake Vrana (Vransko jezero) in Croatia, in April 2011. The cells form short and robust chains with very narrow apertures, often partially occluded by silica membranes. Other distinctive features observable in light microscopy are the shape and orientation of the setae which are very long, straight and robust, diverging in various directions from the chain axis and the single parietal chloroplast extending from valve to valve. Distinct ultrastructural characteristics are the absence of processes either in intercalary or terminal valves and the ornamentation of the valve face with densely distributed ribs spreading from an irregular eccentric hyaline area without a clearly defi ned annulus. The outer surface of the terminal valve is ornamented with small spines and setae are composed of
fl at longitudinal fi laments interconnected with short bars and ornamented with small spines tightly arranged around the setae. Our description agrees well with that reported for the freshwater morphotypes of C. wighamii (syn. C. amanita) and contributes for a reliable distinction of this intriguing taxon from similar morphotypes. This finding supports the interpretation of Chaetoceros wighamii as a freshwater/brackish species and represents the first report of a Chaetoceros species in lacustrine environment in Croatia and possibly in any Central European habitats.

Journal of Phycology, 2007

Skeletonema costatum (Grev.) Cleve emend. Zingone et Sarno and S. grevillei Sarno et Zingone were... more Skeletonema costatum (Grev.) Cleve emend. Zingone et Sarno and S. grevillei Sarno et Zingone were known only from the type material collected from Hong Kong waters more than a century ago. Both species have now been collected as live material, and their morphology and phylogenetic position are investigated in this study. Eight Skeletonema strains isolated from Florida, USA; Uruguay; and Brazil are attributed to S. costatum, while one strain from Oman is ascribed to S. grevillei based on morphological similarity to the type material of these species. In addition, a new Skeletonema species, S. ardens Sarno et Zingone, is described for a strain from Singapore and two from northern Australian waters. Skeletonema ardens has terminal fultoportula processes ending in a tapered, undulate protrusion and long intercalary fultoportulae with 1:1 junctions. The rimoportula of terminal valves is located at the margin of the valve face. No major morphological variations were observed within S. grevillei and S. ardens along a salinity gradient, whereas in S. costatum, the processes shortened and the valves came into close contact at low salinities, as already described for S. subsalsum (Cleve) Bethge. Consistent with their morphology, Skeletonema costatum and Skeletonema subsalsum also had similar rDNA sequences. Skeletonema grevillei and S. ardens were distinct in the large subunit (LSU) phylogeny. Skeletonema ardens exhibited consistent intraspecific genetic differences in both the LSU and small subunit (SSU) rDNA.

Deep-sea Research Part Ii-topical Studies in Oceanography, 2010

Sex is an obligatory event in the life cycle of many diatoms, being the means of restoration of m... more Sex is an obligatory event in the life cycle of many diatoms, being the means of restoration of maximum cell size that counteracts the progressive miniaturization induced by asexual divisions. Nonetheless, sexual stages and evidence for sexual reproduction in diatoms have rarely been directly reported from the marine environment. On September 20, 2006, different stages of the sexual cycle of two species, Pseudo-nitzschia cf. delicatissima and P. cf. calliantha, were detected in surface waters of the Gulf of Naples, at the Long Term Ecological Research Station MareChiara. The sampling date corresponded with a seasonal peak of abundance of the two species, which reached maximum concentrations of 9.1×106 and 7.0×105 cells L−1, respectively. Gametangia, auxospores of different size, and initial cells within and outside the perizonium were observed. Up to 9.2% of P. cf. delicatissima and 14.3% of P. cf. calliantha cells were undergoing sexual reproduction. The sexual event was mainly concentrated in surface waters and no sexual stages were observed a week before or after the date. The low percentage of sexual stages and the short duration of such events are probably the reasons for the scarcity of sexual stage observations in nature.

Journal of Phycology, 2005

The type material of Skeletonema costatum (Greville) Cleve was reexamined with the aims of provid... more The type material of Skeletonema costatum (Greville) Cleve was reexamined with the aims of providing an EM description of the species and clarifying which of the recently recognized Skeletonema Greville species, if any, deserves the epithet costatum. Two permanent mounts and two loose samples from the same collections from Hong Kong Bay were examined. Two distinct Skeletonema species were found in all materials. Based on the original description and on the observation of the lectotype, it was concluded that the most abundant morph in the type material is S. costatum. Cells were heavily silicified and 5–16 μm in diameter. The external processes of the fultoportulae in the terminal valves were open tubules with claw-shaped tips. The intercalary fultoportulae processes were closed flattened tubules with a pore at their base, each attached to two processes of the sibling valve (1:2 junction). The rimoportula had a long process and was located marginally in all valves. The second morph in the type material was described as Skeletonema grevillei Sarno et Zingone sp. nov. Cells were delicate, 4–7.5 μm in diameter, and formed short colonies. The fultoportulae processes in the terminal valves were open tubes having narrow tips with truncated or spiny margins. In the intercalary valves, they formed knuckle-like generally 1:1 junctions. A scallop-work of silica bridges joined the bases of the processes. The rimoportula was marginal in all valves. Neither S. costatum nor S. grevillei match any Skeletonema species that have been recently analyzed by combined morphological and molecular approaches.

Plant Biosystems, 1996

... REFERENCES CRA\VFORD RM, GARDNER C. & MEDLIN LK, 1994 - The genus Attheya. I. A desui... more ... REFERENCES CRA\VFORD RM, GARDNER C. & MEDLIN LK, 1994 - The genus Attheya. I. A desuiption offoirr new taxa, and the transfer ofGonioceros septentrionalis and G. armatus. Diatom Res. 9 27-51. ... (Ed. by CR Tomas),,pp. 5-385. Academic Press, S. Diego. ...

Aquatic Microbial Ecology, 2007

Protist, 2008

Recent studies have shown that the cosmopolitan diatom Skeletonema costatum sensu lato is compose... more Recent studies have shown that the cosmopolitan diatom Skeletonema costatum sensu lato is composed of several morphologically and genetically distinct species. To assess whether the separate species have a cosmopolitan distribution, we analysed 184 strains from marine and estuarine sites worldwide. We identified the strains using light and electron microscopy, and we sequenced the hyper-variable region of nuclear LSU rDNA. All recently described species were genetically distinct, and all but two were morphologically distinct. Variability was found for the only ultrastructural character used to distinguish Skeletonema dohrnii and S. marinoi, which cannot be identified based on morphology alone. Furthermore, multiple genetically distinct taxa, which may represent cryptic species, were found within the S. menzelii and S. tropicum clades. We found that all currently recognized species of Skeletonema are widespread, however, gaps seem to occur in their geographical ranges. For example, some species are found in both the northern and southern temperate latitudes whereas other species appear to have only subtropical to tropical ranges. Skeletonema pseudocostatum and S. grethae seem to have more restricted geographical ranges because the former was not found along American coasts and the latter was encountered only in US waters. A taxonomic update is provided for Skeletonema strains currently available in several culture collections, which could aid reinterpretation of results obtained in comparative studies using these strains.

Journal of Plankton Research, 1998

Journal of Phycology, 2005

Journal of Phycology, 2007