Diatoms are single celled algae related to Kelp and Water Moulds. They are encased in silica shells with two valves. During reproduction the cells divide in two, each of which retains one valve of the shell, growing a new opposing valve, which is slightly smaller and fits flush within the older valve. This means that the Diatoms grow smaller with each new generation, until they reach a minimum size, when they undergo a phase of sexual reproduction, giving rise to a new generation of full-sized cells. The genus Halamphora was first described in 1895 as a subgenus of Amphora, but was elevated to a genus in its own right in 2009. It currently contains 154 species, with a global distribution, predominantly in marine and brackish water environments. Fifteen of these species have been recorded from Korea to date.
In a paper published in the journal Phytotaxa on 8 November 2022, Sung Min An of the Department of Microbial Resources at the National Marine Biodiversity Institute of Korea, Jihoon Kim of the Department of Biodiversity, also at National Marine Biodiversity Institute of Korea, and Nam Seon Kang, Kichul Cho, Jung Lee, and Fun Song Kim, also of the Department of Microbial Resources at the National Marine Biodiversity Institute of Korea, describe a new species of Halamphora from Hampyeong Bay, on the west coast of South Korea.
Samples were collected from an intertidal mudflat in Hampyeong Bay in July 2018, and cultured at the National Marine Biodiversity Institute of Korea. The recovered cells were then examined under light and scanning electron microscopes, with DNA being extracted to determine whether these Diatoms were a new species, and how they were related to other species within the group. The new species is named Halamphora minima, in reference to its small size in comparison to other members of the genus.
Map of sampling localities in Hampyeong Bay, the west coast of Korea. Type locality of Halamphora minima (35º03’41.94’’
N, 126º24’40.06’’ E). An et al. (2022).
The valves are only 5.9-7.4 μm in length and 2.4-3-3 μm in width, whereas most members of the genus exceed 15 μm in length, and the largest can exceed 80 μm. The tests of Halamphora minima have a deeply convex dorsal margin and a nearly straight ventral margin. The ventral side is expanded, and the valves on this size sealed by a series of striae. The raphe (a slit in the ventral edge of the shell) is straight on the and well developed. There is no axial longitudinal line on the dorsal edge. The surfaces of the shell are covered by a series of striae (lines) single on the ventral surface and double on the dorsal surface.
SEM micrographs of Halamphora minima. (11) External whole valve view, with central area (asterisk), and
dorsal raphe ledge (arrow). (12) Internal whole valve view. (13) Detail of external valve apex,with dorsal raphe ledge (arrow). (14) Detail of internal valve apex showing tongue-like proximal helictoglossae (double asterisk), poorly developed distal helictoglossae
(arrowhead), and internal longitudinal rib (arrow). (15) Detail of internal dorsal areolae occluded by hymens (arrows). (16) Dorsal
girdle bands with two rows of poroids. (17) frustules showing the ventral girdle bands with dorsal raphe ledge (arrow). Scale bars: (11)-(14), (16), (17) 1 μm, (15) 0.5 μm. An et al. (2022).
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