<i>Craspedostauros alatus</i> sp. nov., a new diatom (Bacillariophyta) species found on museum sea turtle specimens

Several populations of a new Craspedostauros species were observed on museum specimens of juvenile green turtle and Kemp’s ridleys collected from Long Island Beach, New York, USA. The new taxon, Craspedostauros alatus Majewska & Ashworth sp. nov., exhibits a distinctive set of morphological features typical of the genus, including cribrate areolae, a stauros narrower than the fascia, multiple doubly perforated girdle bands, and two fore and aft chloroplasts, but clearly differs from all known Craspedostauros species in possessing partially fused proximal helictoglossae forming an internal thickening with a shallow central cavity, distinctive external wing-like silica flaps near the apices, and a combination of valve dimensions and stria density not observed in other taxa. The same taxon was identified in the NCMA culture collection (strain CCMP120), isolated in 1967 from a sample collected from the equatorial upwelling zone in the Pacific Ocean. Nine samples from three sea turtle species were collected from the same location (Long Island Beach). Statistical analyses suggested that the epizoic diatom flora composition was not affected by the collection season but differed among sea turtle species. The most significant difference was observed between the samples with and without C. alatus. Samples with C. alatus were always dominated by Achnanthes elongata and Berkeleya cf. rutilans, while those lacking the new taxon were characterized by remarkably higher contributions of epizoic Poulinea species. This observation suggests that the microhabitat provided by each sea turtle differs among specimens, which may be related to the different stages of biofilm development on the host sea turtle. Additionally, the value of zoological museum collections for epizoic diatom surveys is briefly discussed.</p

Six new epibiotic <i>Proschkinia</i> (Bacillariophyta) species and new insights into the genus phylogeny

The diatom genus Proschkinia is a common element of biofilms covering diverse substrata in saline inland or shallow coastal environments. It can be distinguished from other naviculoid taxa by its lanceolate valves with a fistula located within the central area and numerous open girdle bands with a U-shaped cross-section and a single row of perforations on the internal side of the fold. Despite this distinct morphology, frustules of Proschkinia are typically weakly silicified and often overlooked when cleaned diatom material is analysed. The current paper describes six new species of Proschkinia: P. browderiana sp. nov., P. lacrimula sp. nov., P. maluszekiana sp. nov., P. sulcata sp. nov., P. torquata sp. nov. and P. vergostriata sp. nov., found in numerous samples of marine organisms, such as sea turtles (including sea turtle museum specimens), sea turtle-associated barnacles and seagrass from across the three oceans. Some of the newly described taxa were found on multiple individuals belonging to different sea turtle species, whereas others were in samples collected from different continents. Molecular phylogenetic analysis indicated that examined Proschkinia strains formed a monophyletic clade, sister to Fistulifera.</p

Visualization of Chemical Databases Using the Singular Value Decomposition and Truncated-Newton Minimization

We describe a rapid algorithm for visualizing large chemical databases in a low-dimensional space (2D or 3D) as a rst step in chemical database analyses and drug design applications. The compounds in the database are described as vectors in the high-dimensional space of chemical descriptors. The algorithm is based on the singular value decomposition (SVD) combined with a minimization procedure implemented with the e cient truncated-Newton program package (TNPACK). Numerical experiments show that the algorithm achieves an accuracy in 2D for scaled datasets of around 30 to 46%, re ecting the percentage of pairwise distance segments that lie within 10 % of the original distance values. The low percentages can be made close to 100 % with projections onto a ten-dimensional space. The 2D and 3D projections, in particular, can be e ciently generated and easily visualized and analyzed with respect to clustering patterns of the compounds