Gomphonema guayabense E.Reichardt, 2015

Reichardt, Erwin, 2015, Two new species of the genus Gomphonema (Bacillariophyceae) from Guayabo Waterfall, Cuba, Phytotaxa 203 (2), pp. 185-191 : 186-187

Gomphonema guayabense E.Reichardt , sp. nov. ( Figs. 1–14 )

Cells nearly rectangular in girdle view, mantles without additional structures except for the endings of the transapical striae. Valves rhombic-lanceolate, only slightly gomphonemoid-cuneate with obtusely rounded headpole and broadly rounded or subcapitate rounded foot pole. Length 55–95 μm, width 10–15 μm. Raphe lateral, external fissures nearly straight, internal fissures weakly arched. External and internal central raphe endings conspicuously different, the latter about four times wider apart and abruptly deflected to the same side. Axial and central area combined to form a broad rhombic-lanceolate hyaline field. No isolated pore (stigmoid) present in central area. Striae short, slightly radiate, 8–10 in 10 μm, more densely spaced near the ends and clearly elongated near the foot pole. Areolae in striae 24–28, mainly circa 28 in 10 μm.

In SEM external views show irregularly C- to 3-shaped areolar foramina situated in depressions clearly visible in oblique view ( Figs. 9, 12 ). On the mantle the foramina are less arched and more broadly slit-like ( Fig. 10 ), near the footpole the last 2–3 striae consist of small round foramina only ( Fig. 13 ). At the edge of the valve face/mantle junction the interstriae are studded with small granula ( Figs. 9–10, 12 ). Central raphe fissures approximate, straight and slightly expanded to form elongate , slightly drop-shaped central raphe endings ( Fig. 9 ). At the foot pole a large nearly round pore field is present, bisected by the terminal raphe fissure on the valve face, but with poroids running continuously around the lower part of the polar mantle as the raphe fissure terminates within the pore field ( Fig. 13 ). Internally the central raphe fissures are situated in an apically elongated central nodule, deflected to the same side and recurved at their ends ( Fig. 14 ). Helictoglossa at the distal raphe endings shifted to the secondary side especially at the foot pole ( Fig. 11 ). Alveoli with straight margins, stubs or struts are lacking ( Fig. 14 ). Well-developed pseudosepta are present at both poles ( Fig. 11 ).

Type:— CUBA. Salto del Guayabo. From mosses, Andreas Müller, 6 September 2003. Coll. Reichardt sample S2450 (holotype slide S2450- T01 Coll. Reichardt, Botanical Museum Berlin (B) holotype represented by Fig. 1 ; isotype slide Zu 9/99, Hustedt Collection, Bremerhaven ( BRM)) .

Etymology:— This taxon is named after the type locality Salto del Guayabo.

Figures

FIGURES 1–8. Gomphonema guayabense sp. nov. LM images from the type population. 1. Holotype specimen. 8. Girdle view.

FIGURES 9–14. Gomphonema guayabense sp. nov. SEM images from the type population. 9. External view of the central part of a valve with the central raphe endings. 10. External view showing foramina on valve mantle, small granula on the interstriae at the junction of valve mantle/face and the otherwise unornamented mantle.11. Internal view of an entire valve with pseudosepta at both poles.12. External view of foramina on valve face and granula at the junction of valve face/mantle. 13. External view of footpole with pore field, tilted 40°. 14. Internal view of valve centre showing alveoli, central nodule and proximal raphe fissures. Scale bar = 2 μm, except Figs. 9 & 11, scale bar = 10 μm.