Halamphora lombokensis P. B. Hamilton, E. P. Pane, Y. Risjani & C. N. Solak 2024, sp. nov.

Halamphora lombokensis P. B. Hamilton, E. P. Pane, Y. Risjani & C. N. Solak sp. nov. Description (LM). Valves semi-lanceolate to narrowly semi-elliptic with straight ventral and distinctively convex dorsal margins. Valve length 11.0–13.0 μm, breadth 2.0–3.0 μm. Valve ends slightly ventrally bent, rostrate to almost subcapitate. Raphe branches straight. Proximal raphe endings linear, distal raphe fissures not discernible in LM. The axial area narrow and the central area is almost absent. Striae is only visible under SEM. Dorsal striae density 28–32 in 10 µm (Fig. 4 A – J). SEM. Externally, valves are dorsiventral with narrowly convex dorsal margin and straight concave ventral margin. Central area absents on dorsal side and semi-lanceolate on ventral side. Raphe ledge extends from end to end, moderate, more or less equal width and weakly expanded towards the ends. Raphe branches weakly arched. Proximal raphe endings slightly expanded into straight central depressions. Distal raphe endings are hook-shaped. Dorsal striae are composed of uniseriate areolae; areolae elongated to become rounded towards margin. Areolae are composed of two elongated forms. Ventral striae with slit-like areola. Internally, areolae are round to elongate and divided into two pieces. Distal raphe endings terminating with poorly developed helictoglossae. Proximal raphe fissures fused into central helictoglossae. A distinct longitudinal band of silica runs from end to end near the dorsal axial area (Fig. 5 A – H). Material examined. Holotype: slide number CANA 131860 (microscope slide designed as a holotype) in the collection of Nature Museum of Canada. Isotype: Slide No. UB 04 KUTA PSAL stored at the Center of Algae and Environment (ALGAEN Center) at the Faculty of Fisheries and Marine Science, University of Brawijaya, Malang, East Java, Indonesia • Slide no: INDO_Lombok Kuta_B2_(E. Pane)_ Nov 2023 observed at Kütahya Dumlupınar University Herbarium (DUP), Türkiye. Type material. Type material stored at the Center of Algae and Environment (ALGAEN Center), at Faculty of Fisheries and Marine Science, University of Brawijaya, Malang, East Java, Indonesia; subsample CANA 131860, analyzed at the Canadian Museum of Nature. Type locality. Indonesia, Kuta Beach, Lombok Island (GPS 8°53'41.132"S, 116°17'0.042"E), collector: Elya Putri PANE 11.11.2023. Etymology. Named for the Island of Lombok, where the species was found. Distribution and ecology. Observed from the type locality (Temperature 33.3 ° C, pH 7.0, salinity 32 ppt. and dissolved oxygen 18.5 mg. L - 1). Differential diagnosis. The species is similar to Halamphora angustiformis Stepanek and Kociolek (2018: 68), H. attenuata Stepanek and Kociolek (2015: 32), H. borealis (Kützing) Levkov (2009: 175), H. pellicula Stepanek and Kociolek (2018: 50), H. salinicola Levkov & Díaz (Levkov 2009: 220), H. tenuis Stepanek and Kociolek (2018: 45) and H. valdeminutissima Zidarova et al. (2023: 202). Regarding striae density, Halamphora pellicula, H. tenuis and H. valdeminutissima have higher stria densities while the other comparable taxa have lower stria densities. Moreover, H. angustiformis, H. attenuata and H. borealis are larger while H. pellucula and H. valdeminutissima have smaller dimensions and typical long areolae. Halamphora tenuis is distinguished by biseriate areolae. Associated diatom flora. Unidentified species of another Halamphora, Tabularia, and Navicula were other frequent taxa in the sample.