Upsilococconeis dapalistriata gen. nov. & comb. nov. (Bacillariophyta) – a pantropical marine member of Cocconeidaceae

Cocconeis dapalistriata, first described as a member of the genus Cocconeis, is re-examined due to its unique ultrastructure. Both valvocopulae of this taxon show significant differences compared to those found in the genus Cocconeis. They are expanded and show some similarities with those found in Amphicocconeis. On the other hand, terminal parts of the raphe valve (RV) in C. dapalistriata are simple and the raphe valve (RV) striae are composed of small round areolae with a hymenate occlusion with radial slits, similar to those observed in Cocconeis. Campyloneis and Xenococconeis also have expanded valvocopulae but with numerous morphological differences compared to those found in C. dapalistriata. Furthermore, the areolae of the sternum valve (SV) in C. dapalistriata are occluded by a concave velum with no apparent internal slits, and externally ornamented with irregular silica crystals. Upsilococconeis Riaux-Gobin, Witkowski & Risjani gen. nov. is proposed to accommodate the latter taxon. First described from the Western Indian Ocean (Mascarenes), it was subsequently listed from the Western Pacific Ocean (Guam), the South Pacific Ocean (French Polynesia and New Caledonia) and from the Eastern Indian Ocean (Indonesia), and thus may qualify as pantropical.

References

Yonko Gorand (C2M, University of Perpignan Via Domitia) is acknowledged for assistance with SEM, and the anonymous reviewer for constructive remarks.
Brun, J., & Tempère, J. (1889). Diatomées fossiles du Japon. Espèces marines et nouvelles des calcaires argileux de Sendaï et de Yedo. Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 30(9), 1–75.
De Stefano, M., & Marino, D. (2003). Morphology and taxonomy of Amphicocconeis gen. nov. (Achnanthales, Bacillariophyceae, Bacillariophyta) with considerations on its relationship to other monoraphid diatom genera. European Journal of Phycology, 38, 361–370. https://doi.org/10.1080/09670260310001612646
De Stefano, M., & Romero, O. (2005). A survey of alveolate species of the diatom genus Cocconeis Ehr. with remarks on the new section Alveolatae. Bibliotheca Diatomologica, 52, 1–133.
De Stefano, M., Romero, O. E., & Totti, C. (2008). A comparative study of Cocconeis scutellum Ehrenberg and its varieties (Bacillariophyta). Botanica Marina, 51, 506–536. https://doi.org/10.1515/BOT.2008.058
Ehrenberg, C. G. (1838). Atlas von Vier und Sechzig Kupfertafeln ze Christian Gottfried Ehrenberg über Infusionsthierchen. Pls I-LXIV. Leipzig: Verlag von Leopold Voss.
Guiry, M. D., & Guiry, G. M. (2021). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 17 May 2021.
Holmes, R. W., Crawford, R. M., & Round, F. E. (1982). Variability in the structure of the genus Cocconeis Ehr. (Bacillariophyta) with special reference to the cingulum. Phycologia, 21, 370–381. https://doi.org/10.2216/i0031-8884-21-3-370.1
Hustedt, F., & Aleem, A. A. (1951). Littoral diatoms from the Salstone, near Plymouth. Journal of the Marine Biological Association of the United Kingdom, 30, 177–196. https://doi.org/10.1017/S0025315400012662
Jahn, R., Kusber, W.-H., & Romero, O. E. (2009). Cocconeis pediculus Ehrenberg and C. placentula Ehrenberg var. placentula (Bacillariophyta): Typification and taxonomy. Fottea, 9, 275–288. https://doi.org/10.5507/fot.2009.027
Levkov, Z., Krstic, S., Metzeltin, D., & Nakov, T. (2007). Diatoms of Lakes Prespa and Ohrid: About 500 taxa from ancient lake system. Iconographia Diatomologica, 16, 1–613.
Lobban, C.S. (2015). Benthic marine diatom flora of Guam: New records, redescription of Psammodictyon pustulatum n. comb., n. stat., and three new species (Colliculoamphora gabgabensis, Lauderia excentrica, and Rhoiconeis pagoensis. Micronesica 2015-02: 1–49.
Riaux-Gobin, C., & Compère, P. (2008). New Cocconeis taxa from coral sands off Réunion Island (Western Indian Ocean). Diatom Research, 23(1), 129–146. https://doi.org/10.1080/0269249X.2008.9705742
Riaux-Gobin, C., Compère, P., Straub, F., Ector, L., & Taxböck, L. (2017). Cocconeis voigtii F.Meister (Bacillariophyta) and other species from Meister’s and Voigt’s Nagasaki (Japan) material. Nova Hedwigia. Beiheft, 146, 43–62. https://doi.org/10.1127/1438-9134/2017/043
Riaux-Gobin, C., Coste, M., Jordan, R. W., Romero, O. E., & Le Cohu, R. (2014). Xenococconeis opunohusiensis gen. et sp. nov. and Xenococconeis neocaledonica comb. nov. (Bacillariophyta) from the tropical South Pacific. Phycological Research, 62(3), 153–169. https://doi.org/10.1111/pre.12046
Riaux-Gobin. C., Garcia, M., Witkowski, A., Saenz-Agudelo, P., Coste, M. & Daniszewska-Kowalczyk, G. (2021). New Amphicocconeis (Bacillariophyta) from Raivavae and Tahiti Islands (South Pacific) and Porto Belo (Brazil), with re-examination of Psammococconeis. Phytotaxa 513(1): 30–54. https://doi.org/10.11646/phytotaxa.513.1.2
Riaux-Gobin, C., Romero, O. E., Compère, P., & Al-Handal, A. Y. (2011). Small-sized Achnanthales (Bacillariophyta) from coral sands off Mascarenes (Western Indian Ocean). Bibliotheca Diatomologica, 57, 1–234.
Riaux-Gobin, C., Romero, O. E., Coste, M., & Galzin, R. (2013). A new Cocconeis (Bacillariophyceae) from Moorea Island, Society Archipelago, South Pacific Ocean with distinctive valvocopula morphology and linking system. Botanica Marina, 56(4), 339–356. https://doi.org/10.1515/bot-2012-0162
Riaux-Gobin, C., Saenz-Agudelo, P., Górecka, E., Witkowski, A., Daniszewska-Kowalczyk, G., & Ector, L. (2021). Cocconeis vaiamanuensis sp. nov. (Bacillariophyceae) from Raivavae (South Pacific) and allied taxa: Ultrastructural specificities and remarks about the polyphyletic genus Cocconeis Ehrenberg. Marine Biodiversity, 51(29), 1–23. https://doi.org/10.1007/s12526-020-01154-9
Risjani, Y., Witkowski, A., Kryk, A., Yunianta, Gorecka, E., Krzywda, M., Safitri, I., Sapar, A., Dąbek, P., Arsad, S., Gusev, E., Rudiyansyah, Peszek, Ł, Wrobel, R.J. (2021). Indonesian coral reef habitats reveal exceptionally high species richness and biodiversity of diatom assemblages. Estuarine, Coastal and Shelf Science 261 (2021) 107551.https://doi.org/10.1016/j.ecss.2021.107551
Round, F. E., Crawford, R. M., & Mann, D. G. (1990). The diatoms: biology and morphology of the genera. Cambridge University Press.