Giffenia koreana S.D. Lee & M. Park, 2023

Lee, Sang Deuk, Park, Mirye, Lee, Jin-Young, Lee, Hoil & Choi, Jung-Min, 2023, Giffenia koreana sp. nov. (Bacillariophyta): A newly identified epipelic diatom in the tidal flat sediments of Suncheonman Bay, extant for over 1,400 Years, Phytotaxa 629 (3), pp. 187-196 : 189-193

Giffenia koreana S.D. Lee & M. Park sp. nov. ( Figs 3–23 )

Light Microscopy Observations ( Figs 3–8 )

Cells are solitary. Valves have an oval to lanceolate outline, measuring 67.7–80.6 µm in length and 37.5–40.6 µm in width. The valve face is slightly undulated. Around the apical axis, one side is slightly concave while the other side is slightly convex. Valves are symmetric along the apical plane. The sternum appears straight on the side without a raphe, and curved on the side with a raphe. The thin lip-shaped sternum is located nearly at the valve’s center and has a slightly rough surface. Numerous alveoli, situated at a density of 7 per 10 µm, are found on the valve face. The alveoli are almost straight near the center of the valve and become slightly curved closer to the apex.

Scanning Electron Microscopy Observations ( Figs 9–23 )

Valves are oval to lanceolate in valve view ( Figs 9, 10, 12 , 15 ). In girdle view, cells appear rectangular ( Figs 9, 11 , 15 ). The mantle is more or less vertical. The valve face is transapically slightly undulated ( Figs 9 , 15 ). Around the apical axis, the valve surface is slightly concave on one side and slightly convex on the other ( Figs 9 , 15, 17 ). The edges of the valve are slightly rounded ( Figs 9, 13 , 15 ). The lip-shaped sternum is located on the central valve face, which has a slightly rough surface and numerous irregular fine pores ( Figs 9, 10 , 15 , arrow). On one side (raphe-less side), the sternum is straight, and on the other side (raphe side), it is slightly curved outward ( Figs 9, 10, 13 ). The internal valve face features slightly circular openings for the alveoli ( Fig. 12 ). These internal alveolar openings are located through slightly large circular foramina (7 per 10 µm) situated at the junction between the valve face and the mantle ( Fig. 12 ).

An elongated transapical chamber, or alveolus, is located on the outer valve surface ( Figs 13, 14 ). The alveoli are positioned at a density of 7 per 10 µm on the valve surface. The shape of the alveolus is asymmetric relative to the apical axis and consists of conspicuously multiseriate striae (4–5 striae per alveolus). The alveoli are almost straight closer to the center of the valve ( Fig. 16 , arrow) and slightly curved nearer to the apex ( Figs 18, 19 , arrow). The raphe is positioned on one side of each valve, along the mantle ( Figs 11 , 15, 16 ). The two raphes are located on opposite sides of the two valves. On the valve face at the raphe side, rows of striae cease at the valve face’s ends ( Figs 15, 16 ), but on the other side (raphe-less side), rows of striae continue downward onto the mantle ( Figs 14 , 22 ). On the mantle at the raphe-less side, the number of pores increases and their size decreases, leading to irregularly increased pores density within the striae. A hyaline area appears between the raphe slit and the alveoli on the valve ( Figs 16, 18, 19 ). The rows of striae are located at a density of 11 per 10 µm on the valve face. The striae are almost parallel to the transapical axis, except at the apices, where they curve slightly closer to the valve apex. The size of pores near the raphe slit on the valve are larger ( Figs 16, 18, 19 , arrowheads) than those elsewhere on the valve face. The raphe ends are downturned, resembling either a J-shape ( Figs 18, 19 ) or a square root symbol shape (√) at the valve apex ( Figs 17 , 22 ). On the mantle at the raphe side, nail-shaped clusters of areaole are positioned below the raphe slit (7 per 10 µm) ( Fig. 23 , arrows). The girdle consists of three cupulae, first valvocopulae is wide ( Figs 22, 23 ).

Type:— REPUBLIC OF KOREA, Suncheon-si: Collected at a depth of 2.5 m in the tidal flat of Suncheonman Bay wetland (34°52’10.1266” N, 127°29’27.5667” E) on June 11, 2018. Slide NNIBRDI24163 (holotype); Slides NNIBRDI24164 , NNIBRDI24165 , NNIBRDI24166 (isotypes). The holotype and isotypes have been deposited in the NNIBR (Nakdonggang National Institute of Biological Resources) in the Republic of Korea ( Figures 3–8 ).

Ecology and Distribution:— Giffenia koreana sp. nov. is a benthic and epipelic diatom, as the taxon is distributed from the surface to a sedimentary layer at a depth of 6.0 m in the tidal flat of Suncheonman Bay, Republic of Korea, according to this study. The sampling site, Suncheonman Bay, has brackish water conditions with a salinity of 25.87 PSU, a temperature of 20.3 ºC, slightly neutral pH (7.63), high conductivity (40,395 µS/cm), and dissolved oxygen (DO) levels of 5.06 mg /L. The previously known G. cocconeiformis is distributed in Mexico ( Torres-Ariño et al. 2019), Iraq ( Al-Saedy et al. 2020), Kuwait (Al-Kandari & Suburova 2019), India ( Gupta & Das 2020), the Philippines (Ohtsuka et al. 2009, Martinez-Goss 2021), the Republic of Korea ( Lee et al. 2012), and Chuuk Lagoon ( Park et al. 2022). Nitzschia cocconeiformis , a synonym of G. cocconeiformis , is found in South Africa ( Giffen 1967), Iraq ( Maulood et al. 2013, Al-Saboonchi & Al-Shawi 2016), the Philippines ( Martinez-Goss 2021), China ( Liu 2008), and Taiwan ( Shao 2003 –2014). Tryblionella cocconeiformis , another synonym, has been reported in Turkey ( Taskin et al. 2019), India ( Gupta & Das 2020), Singapore ( Pham et al. 2011), Taiwan ( Shao 2003 –2014), Australia ( McCarthy 2013), and Kuwait ( Al-Yamani & Saburova 2011) ( Table 2 ).

Etymology:—The specific epithet koreana refers to the type locality in the Republic of Korea.

Figures

FIGURES 3–8. LM images of the undulating external valve view of Giffenia koreana sp. nov. on the holotype (Figs 3–5) and isotype (Figs 6–8). Fig. 3, 4: The valve face focused on the slightly convex side. Fig. 5: The valve face focused on the slightly concave side, with an uneven central sternum positioned along the apical axis. Figs 6–8: The valve face observed on various focuses. Scale bar: 10 µm.

FIGURES 9–14. SEM images of Giffenia koreana sp. nov. featuring type materials. Fig. 9: A whole cell displaying the thin lip-shaped sternum (arrow), accompanied by numerous alveoli consisting of rows of pores. Fig. 10: The valve face with disrupted rows of pores and the thin lip-shaped sternum (arrow). Fig. 11: Side of the valve showing the continuous, whole raphe slit. Fig. 12: Internal valve face featuring the internal openings of the alveoli. Fig. 13: The valve face with a central thin lip-shaped sternum. Fig. 14: The alveoli with multiseriate pores on the external valve face. Scale bars: 10 µm for Figs 10–12, 14; 20 µm for Figs 9, 13.

FIGURES 15–19. SEM images of Giffenia koreana sp. nov. on the type materials. Fig. 15: A whole cell displaying the central thin lipshaped sternum (arrow), numerous alveoli, and raphe slit. Figs 16–19: A hyaline area between the raphe slit and the alveoli (arrow). Figs 17–19: Valve apex featuring a downturned raphe apex, and with curved alveoli (arrow). Scale bars: 5 µm for Figs 18, 19; 10 µm for Figs 15–17.

FIGURES 20–23. SEM images of Giffenia koreana sp. nov. using type materials. Figs 20, 21: Valve face displaying the terminal valve apex with a hyaline area. Fig. 22: The apex of the epi/hypo-valve featuring a terminal hooked raphe and numerous alveoli. Fig. 23: The mantle showing numerous nail-shaped pores clusters positioned below the raphe slit (arrow). Scale bars: 5 µm for Fig. 21; 10 µm for Figs 20, 22, 23.