Species Description: This is another member of the group formerly included in the section Fusiformes of the genus Navicula (Hustedt 1931-66) and transferred to Haslea by Simonsen (1974). The original description for this species is: “Valves lanceolate with acute to somewhat rounded ends, 150-200µm long, 19.5-22µm wide”. Raphe straight with extremely approximate central pores. Central and axial areas lacking. Structure very delicate; transapical striae parallel, 18-19 in 10µm; longitudinal striae hardly visible (best in interference contrast), 36-40 in 10µm.” Figure 1 (light micrograph, modified from Simonsen 1974; plate 32, Fig. 1a) represents the holotype.
Many of the species transferred into Haslea (Simonen 1974) have not been examined with electron microscopy. A single valve of a Haslea was observed at Port Canaveral, Banana River that corresponds closely to an unpublished photo of H. gretharum type material from the Indian Ocean (F. Hinz via F. Sterrenburg personal communication, 4 Sept. 2014). This valve, the only one seen, is slightly smaller than Simonsen’s description (Fig. 2, SEM external view; Fig. 3, detail of Fig. 2). It does not show the internal structure, so the identification is tentative. Other identification possibilities include H. clevei (Sterrenburg et al. 2015) and H. frauenfeldii (Grunow) Simonsen; until more material is available, this identification is tentative.
Hustedt F. 1931-1966. Die Kieselalgen Deutschlands, Österreich und der Schweiz. In: Dr. L. Rabenhorst’s Kryptogamen-Flora von Deutschlands, Österreich und der Schweiz 7(1): 1-920, 7(2): 1-845, 7(3): 1-816. J Cramer Verlag, Weinheim.
Simonsen R. 1974. The diatom plankton of the Indian Ocean expedition of R/V “Meteor” 1964-1965. “Meteor”Forschungsrgebnisse, Reihe D 19: 1-66, Pl. 1-41.
Sterrenburg FAS, Tiffany MA, Herwig WE, Hargraves PE. 2015. Seven new species expand the morphological spectrum of Haslea. A comparison with Gyrosigma and Pleurosigma (Bacillariophyta). Phytotaxa 207: 143-162.