Bicudoa C.E. Wetzel, Lange-Bertalot & Ector

Wetzel, Carlos E., Lange-Bertalot, Horst, Morales, Eduardo A., Bicudo, Denise De C., Hoffmann, Lucien & Ector, Luc, 2012, Bicudoa amazonica gen. nov. et sp. nov. (Bacillariophyta) - a new freshwater diatom from the Amazon basin with a complete raphe loss in the Eunotioid lineage, Phytotaxa 75 (1), pp. 1-18: 5-7

publication ID

http://doi.org/ 10.11646/phytotaxa.75.1.1

persistent identifier

http://treatment.plazi.org/id/C727879B-FF85-4C16-01DE-DE7EFC4FFD74

treatment provided by

Felipe

scientific name

Bicudoa C.E. Wetzel, Lange-Bertalot & Ector
status

gen. nov.

Bicudoa C.E. Wetzel, Lange-Bertalot & Ector   gen. nov. ( Figs 7–14 View FIGURES 7–20 , 21–32 View FIGURES 21–27 View FIGURES 28–32 , 43–45 View FIGURES 40–54 )

Frustula aspectu cinguli fere rectangulata. Valvae late ellipticae, lineari-ellipticae ad lineares apicibus cuneatis denique curte rostratis. Valvae dorsiventrales quia ad axem apicalem leviter ad levissime asymmetricae margine una semper convexa altera modice concava in mediis partibus quoad specimina media et maiora. Area axialis (id est sternum) angustissima plerumque excentrica sita. Areae angustae marginales prope limbos adsunt. Alterae areae absunt. Systema raphidea nulla. Striae transapicales, sicut in Eunotia   , subparallelae saepe plusminusve irregulariter sitae inter se, sub apices transientes distincte radiantes. Interstriae comparate latiores. Structura chromatophorum incognita. Aspectus externus: Frontes   valvarum fere planae cum foraminibus areolarum uniseriatis omnino comparate minimis circularibus. Series foraminum curte interruptae sterno angustissimo et latius interruptae ad iuncturam inter frontem et limbum valvae ubi series apicalis spinarum verrucosa num est tum series continuantes in limbis. Campi porellorum absunt. Aspectus internus: Superficies   interna perforata areolis circularibus crateriformibus apertis. Depressiones transapicales id est alveoli vacant. Systema raphidea ut in familia Eunotiaceae   sive ut in familia Bacillariaceae   nulla. Etiam rimoportulae et porelli apicales ut in familia Fragilariaceae   et alteris familiis diatomearum araphidearum vacant. Cingulum frustulorum: cingulum utraeque valvae 3–10 copulis apertis vel clausis constans. Omnes copulae preditae multis areolis uniseriatis transapicaliter (vel quodammodo pervalvariter ita ut in Eunotia nec   in familia Fragilariaceae   vel alteris familiis araphideis).

Frustules rectangular in girdle view. Cells forming band-like colonies. Valves isopolar, moderately dorsiventral, broadly linear with slightly constricted centre in large specimens; cuneate to sub-rostrate ends. Dorsal margins consistently convex. Ventral margins variable, either less concave in small valves or nearly straight to concave in medium-sized and large specimens. Axial area or sternum extremely narrow, sometimes displaced toward ventral side of valve or centrally positioned. Narrow lateral area located close to valve margins, visible in both valve and girdle view. Transapical striae sub-parallel often irregularly spaced, becoming radiate toward the ends. Costae comparatively much wider. Plastids unknown. In external view, valve face slightly curved with a shallow longitudinal depression near valve centre. Striae uniseriate situated both on valve face and mantle, interrupted by lateral area developing on junction between valve face and mantle. Areolae small and circular. Sternum narrow, sometimes displaced toward ventral side of valve. Apical pore fields absent. Cingulum composed of 3–10 open copulae, perforated by pervalvar multiporoid striae arranged in discernible rows. Raphe system, helictoglossae and rimoportulae lacking.

Type:— Bicudoa amazonica C.E. Wetzel, Lange-Bertalot & Ector