Meloneis Gen. Nov., a New Epipsammic Genus of Rhaphoneidaceae (Bacillariophyceae)

The diatom family Rhaphoneidaceae is characterized by high generic diversity and low species diversity with most genera known to have long stratigraphic ranges. The genera within this family are neritic marine, and mostly epipsammic. A new modern and epipsammic genus, Meloneis gen. nov., is described herein and is compared to all genera within Rhaphoneidaceae and especially to Rhaphoneis Ehrenberg s.l. Within Meloneis three new species and one variety are distinguished and described herein: M. mimallis sp. nov., M. mimallis var. zephyria var. nov., M. akytos sp. nov., and M. gorgis sp. nov

Periphyton and its colonization in marine hydrothermal regions of island Milos (Greece)

[…] Objective of this thesis is the study - from a systematic point of view - of both periphytic diatoms and endoliths (cyanobacteria, chlorophytes) in island Milos, i.e. at its coastal areas with marine hydrothermal fields or in adjacency with them. Also, all essential data and a bibliographic review of ecology and phytogeography of these organisms are given, as a necessary element for their taxonomy. Material was studied from Palaeochori, i.e. a gulf of island Milos presenting intense hydrothermal activity, and in particular from its supralittoral zone up to depth of 115m. Additionally, the lagoon Ahivadolimni was studied, as a biotope that abuts with the gulf Milos (another gulf of island Milos also presenting hydrothermal activity), as well as Pleistocene marine sediments by Sarakiniko. Specifically, from the gulf Palaeochori, collections of epipsammic diatoms were made from the characteristic zonation (green, yellow, white) of vents as well as epipsammic diatoms in bigger distance than the vents centre, epilithic diatoms from rocky regions of the littoral and supralittoral zones, epizoic and epiphytic diatoms of the littoral zone, as well as endolithic growths from calcareous material of biotic origin. In the lagoon Ahivadolimni, collections of mollusks, microbial mats and chlorophytes were made to study epizoic diatoms, diatoms in microbial mats, epiphytic diatoms, as well as euendolithic cyanobacteria and chlorophytes. By Sarakiniko, fossil material (diatomites) of Pleistocene was studied. Treatment and observation of diatoms and euendoliths were made in accordance with the classic techniques. […][…] Αντικείμενο και στόχος αυτής της διατριβής είναι η μελέτη από συστηματική άποψη των περιφυτικών διατόμων και της ευενδολιθικής μικροχλωρίδας (κυανοβακτήρια, χλωροφύκη) σε παράκτιους βιοτόπους της νήσου Μήλου με θαλάσσια υδροθερμικά πεδία ή σε γειτνίαση με αυτά. Δίνονται επίσης όλα τα απαραίτητα στοιχεία και μία βιβλιογραφική επισκόπηση της οικολογίας και φυκο-γεωγραφίας των οργανισμών αυτών, απαραίτητη για την ταξινομιική τους. Μελετήθηκε υλικό από τον κόλπο Παλαιοχωρίου, ο οποίος παρουσιάζει έντονη υδροθερμική δραστηριότητα, από την υπερπαράλια ζώνη μέχρι βάθους 115m. Συμπληρωματικά μελετήθηκε η λιμνοθάλασσα της Αχιβαδολίμνης ως βιότοπος που γειτνιάζει με τον κόλπο της Μήλου που παρουσιάζει επίσης υδροθερμιικά φαινόμενα, καθώς και η περιοχή Σαρακίνικο με αποθέσεις θαλασσίων απολιθωμένων ιζημάτων από το Πλειστόκαινο. Συγκεκριμένα από τον κόλπο του Παλαιοχωρίου, έγιναν συλλογές επιψαμμικών διατόμων από τη χαρακτηριστική ζώνωση μεμονωμένων αναβλύσεων καθώς και επιψαμμικών διατόμων σε μεγαλύτερη απόσταση από το κέντρο της ανάβλυσης, επιλιθικών διατόμων από βραχώδεις περιοχές της παράλιας και υπερπαράλιας ζώνης, επιζωικών και επιφυτικών διατόμων της παράλιας ζώνης, καθώς και ευενδολιθικών αναπτύξεων σε οργανικής προέλευσης ασβεστιτικό υλικό. Από την Αχιβαδολίμνη έγιναν συλλογές μαλακίων, μικροβιακού τάπητα και χλωροφυκών και μελετήθηκαν τα επιζωικά διάτομα, τα διάτομα του μικροβιακού τάπητα, τα επιφυτικά διάτομα και οι ευενδολιθικοί μικροοργανισμοί. Από το Σαρακίνικο μελετήθηκαν διατομίτες του Πλειστοκαίνου. Οι μέθοδοι επεξεργασίας και παρατήρησης των διατόμων και των ευενδολιθικών μιικροοργανισμών έγιναν σύμφωνα με τις κλασικές τεχνικές. […

External valve views of <i>Meloneis mimallis</i> sp. nov. under SEM.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank"><b>Figure 2A</b></a><b>. </b><i>M. mimallis</i> with two pseudocelli consisting of 5 pores (lower valve apex) & 6 pores (upper valve apex); note the two sizes of edge papillae, the larger ones usually in groups of 3–4 between the areolae rows. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank"><b>Figure 2B</b></a><b>.</b> Detail of the valve apex showing the circular pattern of pseudocellus consisting of 6 pores (black arrow); grey arrow indicates the external opening of the rimoportula; black arrow with white outline points to the extra incomplete row of small papillae (see also the complete rows in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank">Fig. 2C</a>). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank"><b>Figure 2C</b></a><b>.</b> Note the presence of an extra short continuous row of fine papillae at each pole (arrows) (cf. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank">Fig. 2B</a>). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank"><b>Figure 2D</b></a><b>.</b> A specimen with two pseudocelli, consisting of 3 pores (black arrow) & 4 pores (white arrow). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank"><b>Figure 2E</b></a><b>.</b> Detail of the valve end showing the round to ovate rota-type areolae with central pits. [Scale bars: <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank">Figures 2A, C, D</a> = 10 µm, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank">Figure 2B</a> = 1 µm, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g002" target="_blank">Figure 2E</a> = 2 µm].</p

Internal valve views of <i>Meloneis mimallis</i> sp. nov. and <i>Meloneis akytos</i> sp. nov. under SEM.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g003" target="_blank"><b>Figure 3A</b></a><b>.. </b><i>M. mimallis</i> with diagonally positioned rimoportulae in relation to the apical axis. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g003" target="_blank"><b>Figure 3B</b></a><b>.</b> Detail of the apex showing the elongated slit-like internal opening of the rimoportula (black arrow), and the pseudocellus consisting of 4 fine pores (black arrow with white outline). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g003" target="_blank"><b>Figure 3C</b></a><b>.</b> A specimen of <i>M. akytos</i> with distant striae and diagonally positioned rimoportulae in relation to the apical axis. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g003" target="_blank"><b>Figure 3D</b></a><b>.. </b><i>M. akytos</i> showing the elongated slit-like internal opening of the rimoportula (white arrow), and the pseudocellus with 2 fine pores (black arrow). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g003" target="_blank"><b>Figure 3E</b></a><b>.</b> Tilted specimen of <i>M. akytos</i>; note the two (white arrow) or three (black arrowhead) struts of the rotae in the areolae. [Scale bars: <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g003" target="_blank">Figures 3A, C</a> = 10 µm, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g003" target="_blank">Figure 3B</a> = 1 µm, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0032198#pone-0032198-g003" target="_blank">Figures 3D, E</a> = 2 µm].</p

Valve morphology - according to the available literature and photodocumentation cited in this paper - differentiating <i>Meloneis</i> from the related genera of the family Rhaphoneidaceae (for the genus <i>Rhaphoneis s.s.</i> characters of the type species <i>Rhaphoneis amphiceros</i> were considered).

1<p>Fo = fossil, R = recent.</p>2<p>Mu = multipolar, La = lanceolate, Rh = rhomboid, Ell = elliptic, Li = linear, Elo = elongate.</p>3<p>So = solid, Pe = perforate, Co = concentric.</p>4<p>SRa = presence of a single row of areolae even around the apices, SRna = presence of a single row of areolae but not around the apices.</p>5<p>Ps = pseudocellus, RP₁ = apical pore field reduced to 1 pore.</p>6<p>x = number, M = many, F = few.</p>7<p>Ci = rather circular, Di = rather disorganised, Rd = rather radiating.</p>8<p>Rimoportula (R) and Apical Pore Field (Ps, RP₁) in relation to vE = valve edge, and in relation to Lr = last transverse row of areolae. For instance: (R-Lr) = rimoportula positioned between the areolae of the last transverse row, vE→ Ps = pseudocellus positioned next to the valve edge. The question marks indicate unclear position of the rimoportula in relation to pseudocellus and to the last transverse row.</p>9<p>P = presence, A = absence.</p>10<p>Sp = spines, Pa = papillae, A = absence of protrusions.</p

Characters of valve morphology differentiating the four taxa of <i>Meloneis</i>.

<p>Characters of valve morphology differentiating the four taxa of <i>Meloneis</i>.</p

Photosynthetic epibionts and endobionts of Pacific oyster shells from oyster reefs in rocky versus mudflat shores.

The Pacific oyster, Crassostrea gigas (Thunberg), is the main bivalve species cultivated in the world. With global warming enabling its reproduction and larval survival at higher latitudes, this species is now recognized as invasive and creates wild oyster reefs globally. In this study, the spatial distribution of photosynthetic assemblages colonizing the shells of wild C. gigas was investigated on both a large scale (two contrasting types of reefs found in mudflats and rocky areas) and a small scale (within individual shells) using a hyperspectral imager. The microspatial distribution of all phototrophs was obtained by mapping the Normalized Difference Vegetation Index (NDVI). Second derivative (δδ) analyses of hyperspectral images at 462, 524, 571 and 647 nm were subsequently applied to map diatoms, cyanobacteria, rhodophytes and chlorophytes, respectively. A concomitant pigment analysis was carried out by high performance liquid chromatography and completed by taxonomic observations. This study showed that there was high microalgal diversity associated with wild oyster shells and that there were differences in the structure of the phototropic assemblages depending on the type of reef. Namely, vertically-growing oysters in mudflat areas had a higher biomass of epizoic diatoms (hyperspectral proxy at δδ462 nm) and were mainly colonized by species of the genera Navicula, Nitzschia and Hippodonta, which are epipelic or motile epipsammic. The assemblages on the horizontal oysters contained more tychoplanktonic diatoms (e.g. Thalassiosira pseudonana, T. proschkinae and Plagiogrammopsis vanheurckii). Three species of boring cyanobacteria were observed for both types of reef: Mastigocoleus testarum, Leptolyngbya terrebrans, and Hyella caespistosa, but the second derivative analysis at 524 nm showed a significantly higher biomass for the horizontally-growing oysters. There was no biomass difference for the boring chlorophyte assemblages (δδ647 nm), with two species: Eugomontia testarum and Ostreobium quekettii observed for both types of reef. This study shows that oyster shells are an idiosyncratic but ubiquitous habitat for phototrophic assemblages. The contribution of these assemblages in terms of biomass and production to the functioning of coastal areas, and particularly to shellfish ecosystems, remains to be evaluated

RGB composite color images (left) and corresponding NDVI spatial distribution images (right) of Pacific oyster shells sampled in two contrasting oyster reefs.

<p>Arrows indicate low NDVI areas close to the shell umbo.</p

List of the diatom genus found in vertical and horizontal oysters, including details of their relative abundance (%), and their life-forms.

<p>List of the diatom genus found in vertical and horizontal oysters, including details of their relative abundance (%), and their life-forms.</p