Craspedostauros nazmii E. Yilmaz , Witkowski, Solak, 2023

Yilmaz, Elif, Witkowski, Andrzej, Oezdelice, Neslihan, Solak, Cueneyt Nadir, Gastineau, Romain & Durmus, Turgay, 2023, Craspedostauros nazmii sp. nov., a new diatom species (Bacillariophyta) from the Turkish Coast of the Black Sea, PhytoKeys 232, pp. 77-88 : 77

Craspedostauros nazmii E. Yilmaz, Witkowski, Solak sp. nov.

Figs 2 , 3

Type material.

Holotype: Slide Number SZCZ 28843, collection of Andrzej Witkowski at the University of Szczecin. Valves representing the holotype population illustrated in Fig. 2F .

Isotype: Slide number TR_Kastamonu_Doganyurt_EPL_Tem2017 deposited in Kütahya Dumlupınar University (Turkey).

Registration.

http://phycobank.org/103900.

Type locality.

Turkey, Kastamonu Province, seashore in Doğanyurt District, (42°0'29.24"N, 33°27'34.19"E), collected by: Cüneyt Nadir Solak, July 18, 2017.

Description.

LM (Fig. 2A-M ) valves lanceolate to narrow lanceolate, slightly constricted in the middle and with rostrate to subcapitate apices, 29-42 µm in length, 4.5-5.5 µm in width (n = 50). Valves with a slight constriction in the middle, tapering towards narrowly rostrate to subcapitate apices. Axial area very narrow, but distinct, in the valve middle expanding into a central area in a form of stauros encompassing the whole valve width. Raphe branches in LM resolvable, slightly undulate, external proximal raphe endings distinct, tear-like shaped, external distal raphe endings strongly bent in same direction. Transapical striae well resolvable in LM, parallel in the middle, becoming slightly radiate and finally divergent close to apices, 20-21 in 10 µm (Figs 2A-M , 3A-D ).

SEM (Fig. 3A-H ). Valve external view (Fig. 3A-D ), valve face flat composed of one to two rows of areolae. The valve face margin marked by a distinct, continuous apically oriented siliceous rib (transformed vimineae). The transition from the valve face to valve mantle gradual in the valve middle, becoming abrupt at the apices. Hyaline area becoming larger towards to the margins in the centre. Transapical striae uniseriate, composed of 1-3 areolae on the valve face and 4-6 on the mantle in central area, and decreasing to 4 towards the apical mantle (Fig. 3B-D ). The striae of the valve face in the apical part composed of a solitary areola, and increasing towards the valve middle to 2 and finally 3 near the stauros. Areolae variable in size, larger near the raphe with more pores (up to 17) in the cribrate occlusions (Fig. 3B ). Raphe branches slightly undulate with external proximal ends expanded, distant from each other. External apical raphe endings strongly hook-shaped. Prominent wing-like silica flaps partially covering the first row of areolae bordering the raphe sternum present near the apices at valve secondary side (Fig. 3C-D ). Valve centre with hyaline area of the stauros and symmetric with regular areolae. On one side three and on the other one to two rows of areolae at the beginning. Then, two rows of areolae on both sides and finally one row of areola towards the ends (Fig. 3A-D ).

SEM (Fig. 3E-H ). Valve surface internally flat, narrow pore-free longitudinal lines running from apex to apex abruptly marking the face-mantle junction (Fig. 3E ). Raised stauros distinctly narrower than the fascia (Fig. 3F ), broadening and decreasing in thickness close to the valve margins (Fig. 3E-F ). Central internal raphe fissures terminate at slight knob of silica onto rectelevatum (Fig. 3F ). A flatly ended cylindrical knob present at the central nodule. Apical raphe endings terminating within prominent helictoglossae within a relatively expanded pore-free area (Fig. 3G-H ). Areolae externally occluded by cribra, appearing sunken, especially close to the raphe-sternum (Fig. 3F-H ).

Etymology.

This species is dedicated to Nazmi Yilmaz, father of the first author Elif Yilmaz in appreciation for his dedication to support and encourage her.

Distribution and ecology.

The species was observed in Doğanyurt District, Kastamonu Province, Black Sea. The conductivity values at the sampling station were 18.69 mS cm-1, DO values were 8.86 mg L-1, TEMP values were 15.4 °C.

Figures

Figure 2. A-M Craspedostauros nazmii sp. nov., LM micrographs. Scale bar: 10 µm.

Figure 3. SEM micrographs of Craspedostauros nazmii sp. nov. A external view of entire valve B external view of central area C, D external view of valve apex showing wing-like silica flap E internal view of entire valve F internal view of central area showing raphe terminate G-H internal view of valve apex. Scale bars: 10 μm (A, E); 2 μm (B-D, F-H).