Leptothoe, a new genus of marine cyanobacteria (Synechococcales) and three new species associated with sponges from the Aegean Sea

Abstract

Cyanobacterial diversity associated with sponges remains underestimated, though it is of great scientific interest in order to understand the ecology and evolutionary history of the symbiotic relationships between the two groups. Of the filamentous cyanobacteria, the genus Leptolyngbya is the most frequently found in association with sponges as well as the largest and obviously polyphyletic group. In this study, five Leptolyngbya‐like sponge‐associated isolates were investigated using a combination of molecular, chemical, and morphological approach and revealed a novel marine genus herein designated Leptothoe gen. nov. In addition, three new species of Leptothoe, Le. sithoniana, Le. kymatousa, and Le. spongobia, are described based on a suite of distinct characters compared to other marine Leptolyngbyaceae species/strains. The three new species, hosted by four sponge species, showed different degrees of host specificity. Leptothoe sithoniana and Le. kymatousa hosted by the sponges Petrosia ficiformis and Chondrilla nucula, respectively, seem to be more specialized than Le. spongobia, which was hosted by the sponges Dysidea avara and Acanthella acuta. All three species contained nitrogen‐fixing genes and may contribute to the nitrogen budget of sponges. Leptothoe spongobia TAU‐MAC 1115 isolated from Acanthella acuta was shown to produce microcystin‐RR indicating that microcystin production among marine cyanobacteria could be more widespread than previously determined.

Shifting Boundaries: Ecological and Geographical Range extension Based on Three New Species in the Cyanobacterial Genera Cyanocohniella, Oculatella, and, Aliterella

“…Stackebrandt (2006) changed the cut‐off points to higher values which was even more strictly supported by the cut‐offs proposed in Yarza et al (2014; 98.7% for species, 94.5% for genera). Many recent studies have shown that cyanobacterial species have distinct morphological features even above a similarity level of 97.5% (Osorio‐Santos et al 2014, González‐Resendiz et al, 2019, Konstantinou et al 2019) and some authors even suggest a cut‐off level for, for example, genera within the Nostocales of 98% similarity and for species of <99% (Kaštovský et al 2014). An additional and recent example for comparable cut‐off levels in pleurocapsalean cyanobacterial species is the newly described cyanobacterium Odorella benthonica that shows 99.92% similarity to Pleurocapsa minor JQ070059 and is separated by striking morphological and ecological differences (Shalygin et al 2019).…”

Photosynthetic Sponge‐associated Eukaryotes in the Aegean Sea: A Culture‐dependent Approach

“…Since metagenomics studies suggest that microeukaryotic communities in sponges are largely derived from seawater (Cleary 2019) and in combination with the worldwide distribution of A. leptochaete, we could hypothesize that Dysidea avara acquired A. leptochaete from the surrounding Aegean seawater. The photosymbiont community of the sponge D. avara in the Aegean Sea also comprises cyanobacteria such as the recently described Leptothoe spongobia (Konstantinou et al 2019). Previously, Chlorophyta belonging to the genus Desmodesmus have been isolated from the marine sponge Halichondria (Halichondria) panicea (Kravtsova et al 2013).…”

“…The Mediterranean Sea remains understudied as regards sponge-associated eukaryotic microalgae, whereas no information exists for the eastern Mediterranean and the Aegean Sea. Our recent research in the area, which revealed new diversity of photosynthetic prokaryotes associated with Aegean sponge species (Konstantinou et al 2018(Konstantinou et al , 2019(Konstantinou et al , 2020, brought to light several photosynthetic eukaryotes from the same sponges. In this paper, we aim to explore and characterize the diversity of sponge-associated photosynthetic eukaryotes based on a culture-dependent method.…”

The Marine Sponge Petrosia ficiformis Harbors Different Cyanobacteria Strains with Potential Biotechnological Application

“…Phylogenetic relationships among coccoid and filamentous cyanobacteria strains were examined separately, strictly referring to the species and sequence selection reported by Konstantinou and coll. [14,20,39] and refined by Gkelis and coll. [13]…”