Synedropsis abuflosensis Al-Handal, Al-Shaheen, Al-Saedy & Wulff, 2022

Al-Handal, Adil Y., Al-Shaheen, Maitham A., Al-Saedy, Rehab N. & Wulff, Angela, 2022, Synedropsis abuflosensis sp. nov., a new araphid diatom (Bacillariophyceae) from the Shatt Al-Arab River, Southern Iraq, Cryptogamie, Algologie 20 (2), pp. 31-39 : 34

Synedropsis abuflosensis Al-Handal, Al-Shaheen, Al-Saedy & Wulff , sp. nov.

( Figs 1-3)

HOLOTYPE. — Permanent slide deposited in the Botanischer Garten und Botanischer Museum ( BGBM), Berlin, Germany under accession number B 40 0045147. Collectors of specimens are Maitham A. Al-Shaheen and Rehab N. Al-Saedy. Fig. 1 illustrates the holotype. PhycoBank registration number: http://phycobank.org/102683

TYPE LOCALITY. — Abu Flos region , eastern side of the Shatt Al-Arab River, Southern Iraq, 30°27’08”N, 48°01’59”E .

ETYMOLOGY. — The epithet refers to the locality where the species was found.

ECOLOGY. — S. abuflosensis sp. nov. appeared in moderate numbers in the Abu Flos samples. Water conductivity at time of collection was 7.1 µS cm-1 (salinity = 3.3 psu) and water temperature 33 °C. The new species did not appear in any of the other samples collected from several places along the river course, both up and downstream. It was found associated with a cyanobacterial mat, mainly formed by Oscillatoria Vaucher & Gomont spp. Other common diatom taxa present in the samples were Nitzschia obtusa W. Smith , Nitzschia palea (Kützing) W. Smith , Nitzschia elegantula Grunow , Fragilaria koensabbei Al-Handal & Al-Shaheen and F. iraqiensis (Al-Handal & Kociolek) Rioual.

DESCRIPTION

Light microscope observations (LM) ( Fig. 1): Cells solitary, rarely in pairs, with two elongated plastids lying on both sides of the central area ( Fig. 1F, G). Frustules linear in girdle view ( Fig. 1D). Valves linear to weakly linear-lanceolate with rounded apices, slightly inflated in the middle, 32-38 µm long and 1.5-3.5 µm wide (n = 50). Striae resolvable in LM, appearing as very small dots on valve margin.

Scanning electron microscope observations (SEM) ( Figs2; 3): Sternum wide in the middle, becoming narrower towards the apices. Central part of sternum reaches valve margins which are either devoid of striae or with delicate vestigial striae ( Fig. 2A, B). In some specimens the hyaline central part of the sternum is asymmetric, being wider along one valve margin ( Fig. 2A, D). Striae parallel, uniseriate, composed of rounded poroid areolae, one row is near the valve margin and the other on the mantle, 20-26 in 10 µm ( Figs 2C, D, E; 3D). Each areola is occluded by a velum ( Fig. 3E, black arrows). A rimoportula is present at only one apex of the valve with its internal opening oriented apically, positioned mostly opposite to the second row of areolae ( Fig. 3B, arrow). The rimoportula opens externally as a small and irregular slit ( Fig. 3A). The apical slit field is composed of parallel longitudinal slits, 4 at the valve pole with a rimoportula ( Fig. 3B) and 5 at the opposite pole ( Fig. 3C). The cingulum is composed of 3-4 delicate, open and non-porous copulae ( Fig. 3D).