Cocconeis dirupta var. dirupta Gregory

• Main Author: Joh, Gyeongje
• Format: Text
• Language: unknown
• Published: Zenodo 2021
• Subjects: Biodiversity; Taxonomy; Chromista; Bacillariophyta; Bacillariophyceae; Achnanthales; Cocconeidaceae; Cocconeis; Cocconeis dirupta; Cocconeis dirupta var. dirupta gregory; Kerguelen; Kerguelen Islands; Indian; Ashworth; Loch Fyne
• Online Access: https://dx.doi.org/10.5281/zenodo.5788110; https://zenodo.org/record/5788110

10. Cocconeis dirupta var. dirupta Gregory (Figs 27–32, 95) Basionym: Gregory 1857, p. 491(19), pl. IX(1), fig. 25. References: Hustedt 1933, p. 354, figs 809a–c; Kobayasi & Nagumo 1985, p. 99, pl. 2. figs 16–27; Witkowski et al. 2000, p. 105, pl. 39, figs 1–5; Riaux-Gobin et al. 2011, p. 26, pl. 3, figs 9–11, pl. 41, figs 1–6; Lobban et al. 2012, p. 286, pl. 40, figs 1–3; Riaux-Gobin et al. 2016, p. 11, figs 4, 35–38 Description: Valves broadly elliptical, 9–23 μm long, 5–14 μm wide. SV: sternum narrow to broadly lanceolate, fusiform, sometimes slightly retracted in the middle. Transapical striae radiate, crossed by hyaline and longitudinal rows, 15–22 in 10 μm, one median stria often shorter on one or both side of the central area. RV: raphe slightly sigmoid. Sternum narrow and straight. Central area not developed or extended as transversely narrrow fascia, not reaching to the margins. Transapical striae radiate, 24–28 in 10 μm. Remarks: The specimens described herein have valve outlines that are more elliptical rather than round-elliptical to discoid, as described for the lectotype designated by Riaux-Gobin et al. (2016). C. dirupta is distinguished from C. dirupta var. flexella by the straight axial area in the SV. In the literature, Cocconeis dirupta corresponds to two forms: one having large valves with a wide sternum (Kobayasi & Nagumo 1985, Riaux-Gobin et al. 2016) and the other having valves with a strong retraction in the middle of the sternum (Witkowski et al. 2000, Lobban et al. 2012). This species has a wide range in length and width dimensions, and both forms were found in the present study. The identifications were conducted according to the large forms designated by Hustedt (1933), and the small retracted forms by Lobban et al. (2012). The retracted forms collected in local areas have smaller dimensions, 9–17 μm long and 5–9 μm wide. In the smaller forms, transapical striae are abruptly denser at apices. This taxon was reportedly common along oceanic coasts (Witkowski et al. 2000), and in tropical coasts (Riaux-Gobin et al. 2011, Lobban et al. 2012). Here, frequent on seaweeds of the Seogwipo coast of South Korea. : Published as part of Joh, Gyeongje, 2021, Distribution of the genus Cocconeis (Bacillariophyceae) along the Seogwipo coast of Jeju Island, South Korea, pp. 149-179 in Phytotaxa 528 (3) on page 157, DOI: 10.11646/phytotaxa.528.3.1, http://zenodo.org/record/5788071 : {"references": ["Gregory, W. (1857) On new forms of marine Diatomaceae found in the Firth of Clyde and in Loch Fyne, illustrated by numerous figures drawn by K. K. Greville, LL. D., F. R. S. E. Transactions of the Royal Society of Edinburgh 21: 473 - 542, pls. 9 - 14.", "Hustedt, F. (1933) Die Kieselalgen Deutschlands, Osterreichs und der Schweiz unter Berucksichtigung der ubrigen Lander Europas sowie der angrenzenden Meeresgebiete. In: Rabenhorst, L. (Ed.) Kryptogamen Flora von Deutschland, Osterreich und der Schweiz. Akademische Verlagsgesellschaft m. b. h. Leipzig 7 (Teil 2, Lief. 3): 321 - 432, figs 781 - 880.", "Kobayasi, H. & Nagumo, T. (1985) Observations on the valve structure of marine species of the diatom genus Cocconeis Ehr. Hydrobiologia 127: 97 - 103. https: // doi. org / 10.1007 / BF 00004189", "Witkowski, A., Lange-Bertalot, H. & Metzeltin, D. (2000) Diatom flora of marine coasts I. Iconographia Diatomologica Vol. 7. A. R. G. Ganter Verlag K. G., Ruggell. 925 pp.", "Riaux-Gobin, C., Compere, P. & Al-Handal, A. Y. (2011) Species of the Cocconeis peltoides group with a marginal row of unusual processes (Mascarenes and Kerguelen Islands, Indian Ocean). Diatom Research 26: 325 - 338. https: // doi. org / 10.1080 / 0269249 X. 2011.639559", "Lobban, C. S., Schefter, M., Jordan, R. W., Arai, Y., Sasaki, A., Theriot, E. C., Ashworth, M., Ruck, E. C. & Pennesi, C. (2012) Coral-reef diatoms (Bacillariophyta) from Guam: new records and preliminary checklist, with emphasis on epiphytic species from farmer-fish territories. Micronesica 43: 237 - 479.", "Riaux-Gobin, C., Compere, P., Jordan, R. W., Coste, M. & Yesilyurt, J. C. (2016) Cocconeis molesta Kutz., C. diaphana W. Sm. and C. dirupta W. Greg. (Bacillariophyta): type material, ambiguities and possible synonymies. European Journal of Taxonomy 204: 1 - 18. https: // doi. org / 10.5852 / ejt. 2016.204"]}