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

Fig. 3A-M

Holotype.

Slide BR-4682, Fig. 3G represents the holotype, Meise Botanic Garden, Belgium. PhycoBank (http://phycobank.org/103141).

Isotype.

Slide 400, University of Antwerp, Belgium.

Type locality.

Antarctica, Livingston Island, Hannah Point, small pool on a coastal rock north of the penguin rookeries, epilithon. 62°38'30"S, 60°36'32"W. Sample LT10, leg. R. Zidarova, coll. date 04 Feb. 2020.

Description.

LM description (Fig. 3A-H ). Valves weakly silicified, broadly semi-elliptic, with a more or less straight ventral and distinctly convex dorsal margin. Apices protracted, subcapitate in larger valves (Fig. 3A ), becoming only weakly protracted, rostrate in smaller valves (Fig. 3F-G ). Valve dimensions (n = 23): length 16.0-27.5 µm, width 5.0-7.0 µm. Raphe straight. Central raphe endings straight, enlarged (Fig. 3A, F-H ). Terminal raphe fissures not discernible in LM. Axial area narrow, central area absent. Dorsal striae parallel to weakly radiate in the middle, becoming more radiate towards the apices, 24-27 in 10 µm, crossed by several undulating longitudinal lines (Fig. 3A-H ).

SEM description (Fig. 3I-M ). Externally, valves show a narrow, but distinct raphe ledge, slightly elevated and running on the entire length of the valve (Fig. 3I, M ). Central raphe endings relatively close together, weakly dorsally bent, indistinct (Fig. 3M ) to weakly enlarged (Fig. 3I ). Terminal raphe fissures shortly hooked to the dorsal side (Fig. 3I, M ). Dorsal striae on the valve face composed of usually 3-5 transapically elongated, sometimes almost rectangular areolae with recessed finely porous foramina (Fig. 3J ). Areolae forming longitudinal rows (Fig. 3I, M ). On the mantle, areolae get smaller (Fig. 3I ). Distinct marginal dorsal ridge lacking (Fig. 3I, M ). Internally, central raphe endings terminating onto fused helictoglossae. Terminal raphe endings finishing onto small helictoglossae (Fig. 3L ). Areolae internally rectangular, arranged in regular transverse and longitudinal rows between raised virgae and vimines, possessing finely porous recessed foramina (Fig. 3K, L ). Ventral striae only internally observed on the valve face, 33-34 in 10 µm, composed of a single elongated areola (Fig. 3L ).

Etymology.

The new species is named after Prof Dr Snejana Moncheva, phycologist and former Director of the Institute of Oceanology at the Bulgarian Academy of Sciences, to thank her for considering our (RZ, NDzh) employment and career possibilities at the Institute.

Ecology, Antarctic distribution and associated diatom flora.

Halamphora moncheviana was most abundant in the epilithon of a small coastal pool, having a relatively low salinity (6.5 PSU, sample LT10, Table 1 ), where it was found together with Craspedostauros laevissimus (W.West & G.S.West) Sabbe and several Nitzschia , Melosira and Navicula species. Roberts and McMinn (1999, Pl. 1, figs 10-11) recorded the same taxon as Amphora sp. d from the Vestfold Hills on the Antarctic Continent, although their reported valves were slightly larger (length 30-35 µm, width 5-8 µm) and with a slightly coarser striation of “approximately” 22 striae in 10 µm. Nevertheless, the SEM photo of the species, identified as Amphora sp. d in Roberts and McMinn (1999, plate 1, fig. 11), presenting a valve externally with striae, composed of a few transapically elongated areolae on the dorsal side and forming irregular longitudinal lines on the valve face, confirms the conspecificity between the species observed on the Antarctic Continent, and H. moncheviana . Roberts and McMinn (1999) reported the species from hypersaline lakes. Based on their and our findings, H. mocheviana is apparently a very tolerant species to changes in salinity. Likely the same taxon was also depicted by Priddle and Belcher (1981, fig. 3l, as Amphora sp.), which they observed in the epilithon of a large, shallow pool (Pool 7) situated near the sea, together with several species of marine origin, including Craspedostauros laevissimus (reported as Tropidoneis laevissima W.West & G.S.West).

Figures

Figure 3. Halamphora moncheviana sp. nov., valves from the type population from South Bay A-H LM views of several valves G represents the holotype I SEM of an entire valve externally, showing the dorsal striae and the raphe endings J SEM, detail of the areolae externally, showing the recessed porous foramina K SEM, detail of the striae and areolae internally, showing the porous internal areolar foramina L SEM of an entire valve internally M SEM, external view of a valve with areolae arranged in longitudinal lines, most likely in a state of development. Scale bars: 10 µm (A-H); 5 µm (I, L, M); 1 µm (J, K).