Giuseppina Alongi

Changes in the benthic algal flora of Linosa Island (Straits of Sicily, Mediterranean Sea)

Abstract A study of the benthic algal macroflora of Linosa Island (Straits of Sicily, Mediterranean Sea) is presented, aiming to verify possible floristic changes that have occurred in the area, last studied in 1973. We found noticeable changes in the benthic flora, which is now poorer in species than that recorded in the literature (233 species against 305), with a minor decrease in Phaeophyceae and Chlorophyta, and a more significant decrease in the number of Rhodophyta. Only 178 species in the present flora were reported previously, while 127 previously reported were not found during the present study. Conversely, 55 species were newly found. Several species of Fucales, like Cystoseira brachycarpa, C. sauvageauana, C. spinosa, C. zosteroides, Sargassum acinarium and S. trichocarpum, which are characteristic of the Mediterranean Sea photophilic communities on hard substrata and sensitive to any environmental changes, have disappeared.

On the occurrence in Sicily of three Florideophyceae new to the Mediterranean Sea

The authors report on the occurrence in Sicily of three Florideophyceae newly recorded for the Mediterranean Sea: Botryocladia madagascariensis G. Feldmann, Ceramium strobiliforme Lawson et John and Chondria pygmaea Garbary et Vandermeulen. A brief description as well as ecological and phytogeographic data are provided for each species

Lithophyllum frondosum (Dufour) comb. nov. (Corallinaceae, Rhodophyta): the species to which Mediterranean ‘Pseudolithophyllum expansum’ should be referred

A study of Mediterranean specimens identified as Pseudolithophyllum expansum, Lithophyllum expansum sensu Lemoine and Pseudolithophyllum cabiochiae have shown that the taxa represent the same species and the names (except P. expansum, which is a heterotypic synonym of Mesophyllum lichenoides) represent heterotypic synonyms of Melobesia frondosa, previously treated as a synonym of Lithophyllum grandiusculum, and here considered as a distinct species, Lithophyllum frondosum. All specimens have tetrasporangial conceptacles with a diameter greater than 300 μm, and pore canals that narrow towards the top, with the cells adjacent to them oriented more or less obliquely to the roof surface and projecting into, but not completely occluding, the canal. The above characters are shown also by L. bermudense, which is here considered as a further heterotypic synonym of L. frondosum.

Spring Marine Vegetation on Rocky Substrata of the Tremiti Islands (Adriatic Sea, Italy)

Spring aspect of the benthic marine communities on rocky substrata from midlittoral to circalittoral zones of the Tremiti Islands (Adriatic Sea) is described. From a comparison with literature data the disappearance of species characterising well structured infralittoral photophilic communities on rocky substrata like Cystoseira spp. and Sargassum spp., resulted. This finding led us to suppose that a considerable structural deterioration of phytobenthic communities has occurred during the last three decades, probably because of an increase of water turbidity.

The Corallinaceae (Rhodophyta) from the Ross Sea (Antarctica): a taxonomic revision rejects all records except Phymatolithon foecundum

Abstract A study was carried out to determine the status and disposition of Corallinaceae recorded from the Ross Sea (Antarctica), viz. Clathromorphum lemoineanum, Leptophytum coulmanicum, L. laeve and L. foecundum. A re-examination of the type of Lithothamnion coulmanicum (basionym of Leptophytum coulmanicum) showed that it is referable to the genus Phymatolithon because it possesses epithallial cells whose outermost walls are rounded to flattened and meristem cells that are as short as or shorter than their immediate inward derivatives. Such characters were also evident in specimens from McMurdo Sound. Moreover, because all the specimens studied had a conceptacle chamber roof c. 300 μm in diameter, a thallus thickness of up to 1 mm, and buried old conceptacles, they are conspecific with P. foecundum. Studies of specimens from Terra Nova Bay identified as C. lemoineanum and of specimens from Franklin Island identified as L. laeve showed that they should all be referred to P. foecundum. Furthermore, judging by the description and illustrations given by Zaneveld & Sanford [Blumea 26: 205–23 1 (1980)], records of P. foecundum (as L. foecundum) from Cape Hallett and Moubray Bay can be confirmed. Therefore, P. foecundum is the only member of Corallinaceae confirmed to occur in the Ross Sea (Antarctica).

The benthic algal flora on rocky substrata of the Tremiti Islands (Adriatic Sea)

ABSTRACT The results of a floristic study of benthic marine macroalgae on rocky substrata from the Tremiti Islands (Adriatic Sea) are presented. The list of taxa at specific and infraspecific level consists of 226 Rhodophyceae, 59 Fucophyceae and 36 Chlorophyceae. Of these 321 taxa, 147 are newly reported from the Tremiti Islands. Data on the reproductive phenology of each species, and comments on some species of particular interest are also given.

Summer biomass of a population of Phyllophora antarctica (Phyllophoraceae, Rhodophyta) from Antarctica

Results of a study on summer biomass in aninfralittoral population of Phyllophora antarctica A.et E. S. Gepp from Terra Nova Bay (Ross Sea,Antarctica) are reported. The population studied grewat depths of 5 to 12 m. The highest value of biomass(1548 wet g m−2) was found at the end of January at6 m depth. Data showed that biomass depended mainly onthe presence or absence of large heavy specimens, eventhough these were always few in number. Moreover, thevery high number of specimens in weight classes 1 (upto 0.03 wet g) and 2 (> 0.03 to 0.06 wet g) recordedfrom December to January showed a relevant productionof new thalli in that period; the decrease of thetotal number of thalli from 8832 counted on 30December to 4384 counted on 10 February, showed someself-thinning in the population; the occurrence ofnumerous thalli belonging to weight classes 3 (>0.06 to 0.125 wet g), 4 (> 0.125 to 0.25 wet g) and5 (> 0.25 to 0.5 wet g) just at the end of December,allows to conclude that P. antarctica continues togrow, although at low rate, during the period ofwinter darkness. Finally, both the low number ofthalli of weight classes 6 (> 0.5 to 1 wet g) and 7(> 1 to 2 wet g) and the absence of thalli of theweight class 8 (> 2 wet g), recorded at the end ofDecember, indicate that most of specimens reachingduring the winter such weight classes (due to theirability to dark growth), died before summer.

Summer biomass of a population of Iridaea cordata (Gigartinaceae, Rhodophyta) from Antarctica

Results of a seasonal study on biomass in an infralittoral population of Iridaea cordata from Terra Nova Bay (Ross Sea, Antarctica) are reported. Thalli were collected during the IX Italian Antarctic Expedition (austral summer 1993–94). The population studied is that living at depths of 4 to 6 m, where the highest density of plants occurred. The highest value of biomass (wet weight 3440 g m−2) was found at the beginning of summer. In that period 72.5% of biomass was from 128 specimens belonging to weight classes 8 (>16 to 32 g) to 10 (>64 g), corresponding to 13.4% of the population in numbers. Small ( 8 to 16 g) to 9 (>32 to 64 g), which numerically represented 18.5% of the population. Data showed that biomass depended mainly on the presence of large heavy specimens, even though they were always few in number. Moreover, the occurrence of such large thalli at the beginning of summer suggests that Iridaea cordata continues to grow during the long antarctic winter.

On three interesting marine red algae (Ceramiales, Rhodophyta) from the Mediterranean Sea

Abstract Observations on three interesting Ceramiales from the Mediterranean Sea are reported; Ceramium incospicuum Zanardini, Polysiphonia setacea Hollenberg and Rodriguezella pinnata (Kutzing) Schmitz ex Falkenberg. The male reproductive structures on the genus Rodriguezella are described for the first time.

Observations on Cystoseira squarrosa De Notaris (Fucophyceae, Fucales), a Rare and Little Known Mediterranean Species, and Its Typification

Abstract A study of the morphology of the brown alga Cystoseira squarrosa De Notaris, a rare and little known species, was carried out on numerous thalli collected at Torre del Serpe near Otranto (Apulia, Italy). Because the original material of this species, held in the Herbarium of the University of Genova (GE), was destroyed during the Second World War, a neotype is designed here. The species is well characterized by the combination of the following characters: not caespitose, bush-like habit; short primary axis bearing 1–2 secondary axes inserted at right angle; oblong and warty tophules; slightly prominent and smooth apex of the axes; robust, rigid, flattened, not spaced spinose appendages with bifid, trifid or multifid apices and conceptacles grouped at the base of the spinose appendages.