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. 2023 Nov 23;12(23):3941.
doi: 10.3390/plants12233941.

Gandhia gen. nov.-A New Diatom Genus with Unusual Morphology Split Off from the Genus Navicula Bory

Maxim S Kulikovskiy  1 , Mital Thacker  2 , Anton M Glushchenko  1 , Irina V Kuznetsova  1 , Anton A Iurmanov  1 , Balasubramanian Karthick  2 , John Patrick Kociolek  3
Affiliations

Gandhia gen. nov.-A New Diatom Genus with Unusual Morphology Split Off from the Genus Navicula Bory

Maxim S Kulikovskiy et al. Plants (Basel). .

Abstract

A new naviculoid diatom genus, Gandhia gen. nov., was described based on a detailed morphological investigation using light and scanning electron microscopy. Gandhia obtecta (Jüttner and Cox) Kulikovskiy, Glushchenko, Iurmanov, M.Thacker, B.Karthick and Kociolek comb. nov. was previously described as a member of the genus Navicula Bory sensu lato. This species differs from other species in the genus Navicula s.l. by the presence of an internal siliceous lamina covering the alveoli and forming the image of longitudinal lines on either side of the axial area, visible in LM. The presence of this siliceous lamina is similar to laminae in genera such as Pinnularia and Gomphoneis. This unusual morphology is not typical for Navicula sensu stricto, as previously noted by other scientists. Additional investigation of Gandhia obtecta comb. nov. and Gandhia ramosissimoides (H.P. Gandhi) Kulikovskiy, Glushchenko, M.Thacker, B.Karthick and Kociolek comb. nov. from waterbodies of the Western Ghats and the Himalayan region was conducted. Comparison with other species with the same morphological features included two additional species in the genus, namely, Gandhia jakovljevicii (Hustedt) Kulikovskiy, Glushchenko, M.Thacker, B.Karthick, and Kociolek comb. nov. and Gandhia lucida (Pantocsek) Kulikovskiy, Glushchenko, M.Thacker, B.Karthick and Kociolek comb. nov. We discuss the biogeographic patterns of the species, including disjuncts between Europe and Asia.

Keywords: Gandhia; India; Navicula; diatoms; morphology; new genus.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
(A–K). Gandhia obtecta (Jüttner and Cox) Kulikovskiy, Glushchenko, Iurmanov, M.Thacker, B.Karthick and Kociolek comb. nov. (F,G). Valve clearly shows longitudinal lines near the margin on both sides of the axial area (white arrows). Light microscopy, differential interference contrast, size diminution series. Slide no. 33–76 and sample no. AHMA #1639. (A–K). Valve face, size diminution series. Scale bar = 10 μm. Holotype depicted in (K).
Figure 2
Figure 2
(A–F). Gandhia obtecta (Jüttner and Cox) Kulikovskiy, Glushchenko, Iurmanov, M.Thacker, B.Karthick and Kociolek comb. nov. Scanning electron microscopy, external views. (A,B). The whole valve. Note the slit-like lineolate striae, dilated central raphe ends, and hooked distal raphe ends. (C–E). Central area. Dilated central raphe ends are obvious as well as the slit-like striae. (F). Valve end. The slit-like areolae appear to be formed by elongated strips of silica. The hooked raphe end is angular and extends to the valve mantle. Scale bar (A,B) = 5 μm; (C–F) = 1 μm.
Figure 3
Figure 3
(A–F). Gandhia obtecta (Jüttner and Cox) Kulikovskiy, Glushchenko, Iurmanov, M.Thacker, B.Karthick and Kociolek comb. nov. Scanning electron microscopy, internal views. (A,B). The whole valve. The siliceous lamina dominates the valve interior, extending from the center towards the margins. (C–F). Central area. The raphe occurs on an elevated sternum. The siliceous lamina extends over the striae and interstriae. (C,D). Areolae covered with hymens. The raphe is seen as discontinuous. Scale bar (A,B) = 5 μm; (C–E) = 1 μm; (F) = 0.5 μm.
Figure 4
Figure 4
(A–F). Gandhia obtecta (Jüttner and Cox) Kulikovskiy, Glushchenko, Iurmanov, M.Thacker, B.Karthick and Kociolek comb. nov. Scanning electron microscopy, internal views. (A–D). The thickened nature of the interstriae and the alveoli are evident. (E,F). Valve ends. The helictoglossae are distinct and have additional thickenings around the raphe terminus towards the valve apex. The alveolate nature of the striae is evident. Scale bar (A,E) = 1 μm; (B–D,F) = 0.5 μm.
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References

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