Fallacia cinariana H.Sömek, P.B.Hamilton, C.N.Solak, A.Beauger & T.O.Sevindik

Sömek, Haşim, Hamilton, Paul Brian, Solak, Cüneyt Nadir, Beauger, Aude, Yilmaz, Elif & Sevindik, Tuğba Ongun, 2025, A new diatom (Bacillariophyta) species-Fallacia cinariana sp. nov. - from Kaklık Cave in the Western Anatolian Karst Region, Republic of Türkiye, Phytotaxa 694 (2), pp. 173-183 : 176-179

Fallacia cinariana H.Sömek, P.B.Hamilton, C.N.Solak, A.Beauger & T.O.Sevindik

Description ( Figs 2–61 , 110–121 ):— Valves linear to linear-elliptic with broadly rounded, never subcapitate ends. Valve dimensions (n = 24), length 9.0–14.0 μm, width 3.5–4.0 μm. Length-to-width ratio 2.4–3.8 ( Figs 2–61 ). Valve flat and not areolae on mantle, except at the apices ( Figs 110, 112 ). Externally, raphe filiform, almost straight to weakly curved ( Figs 112, 113 ). Proximal raphe endings distinctly expanded drop-like ( Fig. 111 ), distal raphe endings considerably hooked two-point deflection on valve face. Axial area composed of narrow raphe sternum and valve face pore slits/occlusions on either side, 500–900 nm length and 230–280 nm width ( Figs 114–117 , arrows). Central area approximately circular, appearing somewhat diffuse, sometimes indistinct but separated from axial area. Axial area sometimes indistinct. Internally, raphe branches filiform and straight, with slightly dorsally curved proximal endings deflected to same side ( Fig. 119 ); distal raphe fissures end in small helictoglossae at mantle ( Figs 120, 121 ). Striae parallel to weekly radiate, becoming subparallel near the endings, 31–33 in 10 μm. Areolae not discrenable in LM. Along each end, 5–8 extended marginal pores are present ( Figs 112, 113 black arrows –117).

Type:— TÜRKİYE. Denizli, Kaklık Cave, collected from travertines (37°51'22'' N and 29°23'13'' E, 514 m a.s.l.), Cüneyt Nadir SOLAK, 18 September 2015 (holotype TR_DNZ_ Kaklık Cave _Travertine_ Sept2015 deposited at Kütahya Dumlupınar University, Türkiye). Valve representing the holotype population here illustrated in Fig. 5 ; isotype CANA 131863 , Nature Museum of Canada , Canada .

Registration: http://phycobank.org/105306

Etymology:— The species is dedicated to Çınar SÖMEK, son of colleague Dr. Haşim SÖMEK. According to art. 60.4 of the International Code of Botanical Nomenclature, the spelling of the name Çınar is changed to Cinar ( Turland et al. 2018).

Distribution:— Observed from the type locality.

Differential diagnosis:— For most Fallacia taxa, valve outline and stria density separate and distinguish species. F. subhamulata (Grunow) D.G.Mann (1990: 669) , F. lange-bertalotii Reichardt (1885: 176) , Fallacia angarae Metzeltin, Kulikovskiy & Lange-Bertalot in Kulikovskiy et al. (2012: 104), F. emmae van de Vijver & Cox (2015: 247) , F. helensis (Schulz) D.G:Mann in Round et al. (1990: 668), F. lenzii Lange-Bertalot (2004: 159) , and F. pseudohelensis Kulikovskiy, Metzeltin & Lange-Bertalot in Kulikovskiy et al. (2012: 109) are similar to F. cinariana in general morphology and outline. Falacia subhamulata is an old species which is similar to F. cinariana , but separated by the larger size, wider valves, lower striae density, larger central area and elliptic to curved-elliptic valve face terminal pores. Fallacia lange-bertalotii is also similar, however, F. cinariana has visible apical slit-occlusions and smaller round to elliptic pores around the mantle apex which occur in the same density as F. lange-bertalotii . Fallacia angarae , F. helensis and F. pseudohelensis are larger while, F. emmae is narrower than F. cinariana . Among them, F. helensis has triundulate margins and, F. lenzii and F. emmae have higher striae densities.

Ecology:— Kaklık Cave had water temperatures, pH, dissolved oxygen content, and electric conductivity at 23.5 ° C, 8.2, 8.1 mg.L- 1 and 814 µS. cm-1, respectively.

Associated diatom flora:— There was a rich flora in Kaklık Cave with many dominant potentially new species in the genera The dominant genera in densities were Craticula, Crenotia and Achnanthidium . Diploneis oblongellopsis Lange-Bertalot &A.Furhman , Fallacia lange-bertalotii (E.Reichardt) E.Reichardt and Stauroneis pseudosubobtusoides H.Germain were also frequent taxa in the sample.

Figures

FIGURES 2–109. Fallacia taxa in Kaklık Cave. 2–61. Fallacia cinariana sp. nov. LM micrographs. 62–109. F. lange-bertalotii LM micrographs. Scale bar: 10 μm.

FIGURES 110–117. Fallacia cinariana sp. nov. SEM micrographs. 110. General external valve view. 111. Detail of the central area showing proximal raphe ending. 112, 113. Detail of the apices showing distal raphe endings. Arrow highlights a valve face slits on the valve face, black arrows highlights pores on the mantla at the apex. 114–117. Detail of apical pore occlusions. Arrow highlights thicken nodules on the valve face.

FIGURES 118–121. Fallacia cinariana sp. nov. SEM micrographs. 118. General internal valve view. 119. Detail of the central area showing proximal raphe ending. 120, 121. Detail of the apices showing distal raphe endings.