Gomphonema curatorum E.Reichardt, 2015

Reichardt, Erwin, 2015, Two new species of the genus Gomphonema (Bacillariophyceae) from Guayabo Waterfall, Cuba, Phytotaxa 203 (2), pp. 185-191 : 189

Gomphonema curatorum E.Reichardt , sp. nov. ( Figs. 15–34 )

Cells in girdle view barely clavate, nearly rectangular, mantles without additional structures except for the endings of the transapical striae. Valves only slightly gomphonemoid-cuneate, lanceolate with obtusely rounded ends. Larger valves somewhat inflated at mid-valve. Length 31–72 μm, width 6–9 μm (initial valves up to 13 μm). Raphe lateral, external fissures weakly arched to nearly straight, internal fissures slightly more arched. External and internal central raphe endings clearly distinguishable, the latter wider apart and deflected to the same side. Axial and central area combined to form a broad lanceolate hyaline field. No stigmoid present in central area. Striae slightly radiate to nearly parallel, 9–12 (mostly 10–12) in 10 μm, more densely spaced near the foot pole. Areolae in striae difficult to distinguish.

In SEM most ultrastructural details correspond to G. guayabense ( Figs. 28–34 ) but G. curatorum lacks the granula present at the edge of the valve face/mantle junction in G. guayabense ( Figs. 29–30, 32–34 ) and the pore field at the foot pole is clearly smaller ( Fig. 30 ). The foramina in the axial area are often more clearly C-shaped ( Figs. 32, 34 ) and roundish to kidney-shaped depressions can be present around the external central raphe endings ( Fig. 32 ). Helictoglossa at the internal distal raphe endings only slightly or inconspicuously shifted to the secondary side ( Fig. 28 ).

Type:— CUBA. Salto del Guayabo. From mosses, Andreas Müller, 6 September 2003. Coll. Reichardt sample S2450 (holotype slide S2450- T02 Coll. Reichardt, Botanical Museum Berlin (B), holotype represented by Fig. 18 ; isotype slide Zu 9/99, Hustedt Collection, Bremerhaven ( BRM)) .

Etymology:— This taxon is dedicated to all curators of diatom collections, especially to Friedel Hinz, curator of the Friedrich Hustedt-collection at Bremerhaven (BRM) for many years.

Distribution and Ecology:— Gomphonema guayabense and G. curatorum are only known from the type locality so far. The diatom flora of the type material is dominated by species of the genera Achnanthidium, Encyonema and Encyonopsis which often occur with strong appearance in semi aquatic habitats like trickled mosses ( Reichardt 2011). However, there is a remarkable occurrence of Brachysira australofollis Lange-Bertalot & Moser (1994: 17) in this sample, constituting about 6% of the diatom population. Brachysira australofollis is only known from New Caledonia and was found there associated with diatoms like e.g. Brachysira spp. and Frustulia spp. indicating acidic water. Diatoms of these genera are also present in the sample from Salto del Guayabo, Cuba. Therefore similar ecological conditions can be postulated.

Figures

FIGURES 15–34. Gomphonema curatorum sp. nov. LM and SEM images from the type population. 15–27. LM images. 15. Initial valve. 18. Holotype specimen. 27. Girdle view. 28–34. SEM images. 28. Internal view of an entire valve. 29. External view of an entire frustule, tilted 40°. 30. External view of footpole with pore field. 31. Internal view of valve centre showing alveoli without stubs or struts and curved proximal raphe fissures. 32. External view of the central part of a valve tilted 40° showing foramina and depressions near the central raphe endings. 33. External view of the central part of a valve lacking depressions in the central area. 34. External view of headpole, foramina at the border of the axial area strongly C-shaped. Scale bar (SEM) = 2 μm, except Figs. 28 & 29, scale bar = 10 μm.