Halamphora kenderoviana Zidarova, P.Ivanov, Dzhembekova, M.de Haan & Van de Vijver, 2022

Zidarova, Ralitsa, Ivanov, Plamen, Dzhembekova, Nina, Haan, Myriam de & Vijver, Bart Van de, 2022, Two new Halamphora (Bacillariophyta) species from the marine coasts off Livingston Island, Antarctica, PhytoKeys 195, pp. 161-174 : 161

Halamphora kenderoviana Zidarova, P.Ivanov, Dzhembekova, M.de Haan & Van de Vijver sp. nov.

Fig. 2A-M

Holotype.

Slide BR-4681, Fig. 2D represents the holotype, Meise Botanic Garden, Belgium. PhycoBank (http://phycobank.org/103140).

Isotype.

Slide 401, University of Antwerp, Belgium.

Type locality.

Antarctica, Livingston Island, South Bay, Mongolian (Reserve) Port, small pool on a coastal rock during low tide, epilithon. 62°38'50"S, 60°22'26"W. Sample MO’, leg. R. Zidarova, coll. date 21 Dec. 2018.

Description.

LM description (Fig. 2A-I ). Valves semi-lanceolate to narrowly semi-elliptic, with a straight ventral and distinctly convex dorsal margin. Valve dimensions (n = 27): length 13.5-20.5 µm, width 3.5-4.5 µm. Apices slightly ventrally bent, in larger valves protracted, rostrate to almost subcapitate (Fig. 2B ), in smaller valves weakly protracted, subrostrate (Fig. 2F-I ). Raphe branches straight. Central raphe endings expanded, slightly dorsally bent (Fig. 2A, C, I ). Distal raphe fissures not discernible in LM. Axial area narrow. Central area on the dorsal side very small to usually absent, on the ventral side clearly enlarged. Dorsal striae parallel to weakly radiate in the middle, becoming more radiate towards the apices, 18-20 in 10 µm. Occasionally, one or two striae in the valve middle shortened (Fig. 2E, G ), forming a very small dorsal central area. Ventral striae discernible in LM, interrupted in the valve middle (Fig. 2C-F, I ), 27-28 in 10 µm.

SEM description (Fig. 2J-M ). Externally, valves possess a distinct raphe ledge, running along the entire length of the valve, clearly widened in the valve middle, truncated and slightly expanded at the apices (Fig. 2J, M ). Central raphe endings positioned relatively close together, slightly bent towards the dorsal side and pore-like enlarged (Fig. 2J, M ). Terminal raphe fissures hooked to the dorsal side (Fig. 2J, M ). Dorsal striae biseriate, composed of rounded poroids, the latter 60-65 in 10 µm. Striae continuing on the mantle, following a narrow dorsal ridge (Fig. 2M ), where often reduced to a single, large areola (Fig. 2J ). Striae on the ventral side short, composed of only one or two rounded areolae, often fused to form a single elongated areola (Fig. 2J ). Internally, central raphe endings terminating onto a fused central helictoglossa (Fig. 2K ). Terminal raphe endings finishing onto small helictoglossae (Fig. 2K ). Striae internally located between narrow, quite prominently raised virgae (costae). Areolae internally occluded by individual hymenes (Fig. 2L ).

Etymology.

The new species is named after our colleague Dr Lyubomir Kenderov, hydrobiologist at the Faculty of Biology, University of Sofia, with whom RZ shared two Antarctic seasons, and who was often a helping hand during field work in Antarctica.

Ecology, Antarctic distribution and associated diatom flora.

Halamphora kenderoviana was typically observed in tidal pools ( Zidarova et al. 2022, as Amphora sp.5), but only found in abundance (17.5% of the counted valves) in the type locality, a tidal pool with alkaline water and a salinity level of 33.1 PSU (Table 1 ). Other common taxa in the sample are Parlibellus rhombicus W.Greg., Tabulariopsis australis (Perag.) D.M.Williams, and several Navicula species, including N. aff. perminuta Grunow and N. glaciei Van Heurck. So far, H. kenderoviana is known to be present with certainty on the marine coasts of the South Shetland Islands (Livingston Island). Earlier, Cremer et al. (2003) reported a very similar taxon as Amphora coffeaeformis ( Cremer et al. 2003, fig. 13) from sediment cores in Windmill Island, East Antarctica. SEM observations will be needed to confirm that it is conspecific with H. kenderoviana , but it seems likely that at least some of the records of A. coffeaeformis , transferred to Halamphora by Levkov (2009) as H. coffeaeformis ( Kütz.) Levkov, from saline waters in Antarctica might represent H. kenderoviana .

Figures

Figure 2. Halamphora kenderoviana sp. nov., valves from the type population from South Bay, Livingston Island A-I valves under LM, with fig. A showing an entire frustule D represents the holotype J two valves under SEM externally with details of the central raphe endings and mantle areolae K SEM of an entire valve internally L SEM of a valve internally, showing the prominent raised costae between the striae and the internal areolar occlusions M SEM of an entire valve externally, with a view on the mantle and the dorsal ridge. Scale bars: 10 µm (A-I, M); 5 µm (J-L).