New findings of Nudipleura (Mollusca: Gastropoda) along the central-eastern coast of Sicily (Ionian Sea)

The present short note reports the finding of five Nudipleura species: one (Taringa cf. telopia) new for the Mediterranean, two (Doto maculata and Okenia longiductis) new for Sicily, one (Berthella stellata) new for the central-eastern coast of Sicily and, finally, a new record of Taringa tritorquis for the same area. For each species, information on date and site of finding, external morphology, taxonomic history, previous reports and remarks, are discussed. The finding of these species could depend on two different reasons: 1) the examined areas are transit zones for several ships which could transport the veligers or/and juvenile stages through fouling or ballast water; 2) since in these areas the marine Heterobranchia fauna has been poorly studied, many of the found species could have been overlooked until now. This work highlights the importance of a continuous monitoring to expand and deepen the knowledge of marine Heterobranchia fauna

Tapetal Ultrastructural Changes During Pollen Development. II. Studies on Pelargonium Zonale and Kalanchoë Obtusa

SUMMARYThe ultrastructure of the tapetal cells was studied in Kalanchoe obtusa and Pelargonium zonale. In an early stage of development the most characteristic feature was the presence of many spherical bodies bounded by a single membrane and containing cytoplasmic material. These bodies were localized in dilations of the ER and in the perinuclear space. In later stages, when the pollen was mature, the tapetal cells of Pelargonium contained many « grey » bodies and their plasmalemma was in close connection with the sculptures of the pollen grains

Observations on the ghost fishing in two species of marine heterobranchs (Mollusca Gastropoda): Aplysia depilans Gmelin, 1791 (Aplysidae) and Umbraculum umbraculum ([Lightfoot], 1786) (Umbraculidae)

The present note reports for the first time the finding of two species of marine Heterobranchia within a ghost net. The stretch of the net was repeatedly wrapped in itself and formed a large tangle of spherical shape. This created several "layers" of meshes wrapped in each other, where the following species of marine heterobranchs were found: Aplysia depilans and Umbraculum umbraculum. In particular, of the former, an alive specimen was found tied to the wire of the net, and a dead specimen floating within the ghost net. Of the second species, only the shell was found

Assessment of grazing impact on deep canopy-forming species in the western Ionian Sea, Central Mediterranean

Marine forests are experiencing a severe decline in many Mediterranean areas. One of the major causes of the loss of the canopy-forming species is the overgrazing by herbivorous fishes. In the present study, the status of Treptacantha ballesterosii and Carpodesmia zosteroides populations was checked in two areas located along the central-eastern sector of Sicily. In addition, impact of herbivorous fishes, native or alien, on canopy-forming species was realized during monitoring of fish communities. It was observed that T. ballesterosii and C. zosteroides populations are in regression, particularly T. ballesterosii. Probably, the growth of this latter species may be limited by a strong herbivores' pressure. During the monitoring period, the highest number of fish species has been observed at the depths where there are T. ballesterosii thalli. Moreover, an expansion of Sparisoma cretense populations has been observed that seems to be more competitive than the other herbivorous fish Sarpa salpa. Furthermore, the parrotfish has been observed several times in the bathymetric range where there is T. ballesterosii. Therefore, it may be hypothesized that in these areas the herbivorous fish which mostly hinder the development and growth of T. ballesterosii is S. cretense

Tapetal Ultrastructural Changes During Pollen Development. I. Studies on Antirrhinum Maius

SUMMARYAnther sections of Antirrhinum maius in various stages of development have been examined with the electron microscope and the ultrastructural modifications of the tapetal cells have been followed during the development of the pollen grains. Characteristic of the early stages of development is the presence of a great number of intensely proliferating Golgi bodies and of spherical bodies, located in the perinuclear space in proximity of the plasmalemma and in the endoplasmic reticulum. They are bounded by a single membrane on which ribosomes are regularly ranged facing the body cavity. Probably the bodies located in the perinuclear space play a role in the nuclear-cytoplasmic information exchanges, while those in connection with the endoplasmic reticulum seem to be simply related to an enhanced endoplasmic reticulum activity. In the late tetrad stage a second body population appears. These bodies are spherical, electrondense and without bounding membrane. They are located at the cell periphery toward..

Stylar peroxidases and heteromorphic incompatibility reactions in Primula acaulis Hill («thrum» morph)

SUMMARYIn non-, self- and cross-pollinated styles of Primula acaulis «thrum» morph, the distribution of apoplastic peroxidase activity has been investigated, by means of the cytochemical treatment with diaminobenzidine. Apoplastic peroxidase activity was detected throughout the transmitting tract (at the «neck» region level) in non- and self-pollinated styles. The enzyme has been related to the predisposition of incompatible pollen tube rejection, no appreciable differences in enzyme distribution having been found between non- and self-pollinated styles since, in this morph, incompatible pollen tubes hardly ever reach the stylar neck. Compatible intermorph pollination caused the disappearance of apoplastic peroxidase activity in the central portion of the transmitting tract, where pollen tubes elongated, utilizing the reserves of the stylar cells, which appeared highly degenerate. Stylar apoplastic peroxidases seem then to play a role in heteromorphic incompatibility responses

Ultrastructure of pollen of Vitis vinifera L. cv. "Picolit giallo" and its behaviour in experiments of self- and cross-pollination

The ultrastructure of the pollen and stigma of Vitis vinifera L. cv. "Picolit giallo" was studied by scanning and transmission electron microscopy, with the aim of finding out if they presented abnormalities which could account far the low procluctivity of this vine variety. The pollen protoplast has a normai aspect, but its wall is continuous and does not present furrows and germinative pores as pollen grains generally do. The stigma appeared normai. The presence of an uninterrupted wall most probably constitutes an obstacle to pollen germination and is likely to be one of the causes of the low fertilization incidence of "Picolit giallo". This hypothesis is supported also by the results of the experiments of self- and cross-pollination, because Picolit pollen always failed to germinate, even if put on stigmas of other vine varieties, while the pollen of these varieties germinated regularly when put on Picolit stigmas.Die Feinstruktur der Pollenkörner von Vitis vinifera L. cv. Picolit giallo und ihrVerhalten bei Versuchen zur Selbst- und FremdbestäubungDie Vitis-vinifera-Sorte Pìcolit giallo liefert nur geringe Erträge. Um hierfür verantwortliche Abnormitäten aufzufinden, wurde die Feinstruktur von Pollenkörnern und Narbe mit Hilfe der Raster- und Transmissionselektronenmikroskopie untersucht. Der Protoplast der Pollenkörner wirkt normal, aber die Pollenwand ist von kontinuierlicher Beschaffenheit und zeigt keine Furchen oder Keimporen wie bei typischen Pollenkörnern. Die Narbe macht einen normalen Eindruck. Sehr wahrscheinlich verhindert die nicht unterbrochene Pollenwand die Pollenkeimung und ist somit eine mögliche Ursache der geringen Fertilität von Picolit giallo. Diese Vermutung wird durch Versuche zur Selbst- und Fremdbestäubung gestützt, wobei Picolit-Pollen nie keimte, auch dann nicht, wenn er auf Narben anderer Rebensorten gebracht wurde; umgekehrt keimte der Pollen solcher Sorten regelmäßig, wenn er auf Picolit-Narben übertragen wurde

The Fucales (Ochrophyta, Phaeophyceae) of the Island of Pantelleria (Sicily Channel, Mediterranean Sea): a new contribution

In the past, only a few studies were carried out on the marine vegetation of the Island of Pantelleria, reporting a high level of biodiversity in this island. However, the most recent study, performed about 20 years ago, documented a total loss of Fucales below ca. 12 m of depth and their substitution with morphologically simpler species. In the present study, the current presence and distribution of Cystoseira s.l. and Sargassum around the Island of Pantelleria were assessed, comparing the current data with the previous studies on the marine vegetation of this island. Through monitoring activities (both snorkelling and scuba diving), 19 taxa were recorded: seven belonging to Cystoseira, six to Ericaria, four to Gongolaria, and two to Sargassum. Comparing these data with the previous studies, it was highlighted that most of the species previously reported are still present on the island. Moreover, approximately 20 years after their documented disappearance, deep-water species such as C. foeniculacea f. latiramosa, G. elegans, G. montagnei, G. montagnei v. compressa and Sargassum cf. acinarium were recorded during this study, suggesting a natural recovery for these Fucales. We recommend that, in order to guarantee a long-term conservation of these fucalean populations, it would be useful to establish a marine protected area in the Island of Pantelleria

Population dynamics of Ericaria zosteroides (Ochrophyta, Fucales) in the central Mediterranean

Ericaria zosteroides is a canopy-forming macroalga belonging to the order Fucales, which dominates Mediterranean deep-water stands. In the present research, populations of E. zosteroides from three locations (Santa Maria La Scala, Scalo Pennisi and Acque Fredde) along the central-eastern coast of Sicily (Italy, central Mediterranean) were monitored for five years (from 2017 to 2021). E. zosteroides from all locations in this area share a common phenology: recruits start to appear between January-February; then during spring the frond grows and becomes fertile; in summer it begins to thin out until the autumn when almost all branches have been lost; and finally at the beginning of winter, new primary branches start to grow from the tophules. Nonetheless, we detected a difference in the most frequent size class among the studied populations, being 9 cm at Santa Maria La Scala, 6 cm at Scalo Pennisi and 4 cm at Acque Fredde. This difference could be due to the current regime, related to the tidal currents of the Strait of Messina and upwelling currents of the Ionian Sea, and the coastal morphology which determines local variations in this regime, with multiple eddies characterised by marked directional instability. The low growth rate and dynamics of these stands make them very susceptible to recovery from anthropogenic impacts. Considering that E. zosteroides is a threatened species according to the Barcelona Convention, it would be crucial to ameliorate the conservation status of the investigated populations, which currently do not present any level of protection, in order to promote their future viability

No longer so common: findings of <em>Calliopaea bellula</em> d’Orbigny 1837 (Gastropoda: Sacoglossa) and <em>Tayuva lilacina</em> (A. Gould 1852) (Gastropoda: Nudibranchia) along the central-eastern coast of Sicily (Ionian Sea)

The present note documents the finding of two species of marine heterobranch seaslugs along the central-eastern coast of Sicily (Italy, central Mediterranean): the sacoglossan Calliopaea bellula and the nudibranch Tayuva lilacina. These two species show a wide geographical range (C. bellula is present from Norway to the Black Sea, while T. lilacina is a cosmopolitan species) and in the literature were considered common species. However, in the last years, the number of findings of these species is decreasing, at least in the Western Ionian Sea, an area where these species seem to be currently rare. As documented for other Mediterranean areas, the reason for this decline in the number of marine heterobranch species might be attributable to a change in the current regime or to an increase in anthropogenic impacts around the coastal areas