Tetmemorus furcatus G.J.P.Ramos & C.W.N.Moura, 2019

Ramos, Geraldo José Peixoto, Costa, Fabiana De Matos, Santos, Maria Aparecida Dos & Moura, Carlos Wallace Do Nascimento, 2019, Taxonomic novelties, new records, and rare species of desmids from the Chapada Diamantina region, Brazil, Phytotaxa 391 (3), pp. 185-196 : 194

Tetmemorus furcatus G.J.P.Ramos & C.W.N.Moura , sp. nov. ( Figs 63–65 )

Cell distinctly longer than wide; cell outline roughly cylindrical, median constriction shallow; cell fusiform, lateral margins smooth, slightly concave, converging toward the apices, apical margin bifurcate, with an incision deep, open, V-shaped; cell wall smooth, finely punctuated; semicells circular in apical view, fusiform in lateral view. Cell dimensions: length 85–96 μm, width 26–28 μm, isthmus 23–26 μm.

Holotype: material numbered ( HUEFS 244148 !) deposited at Herbário da Universidade Estadual de Feira de Santana , population illustrated here in LM ( Figs 63–65 ).

Etymology: The epithet refers of furcate incision in the apices of semicells.

Type locality and habitat characteristics: Collected at “Vale do Capão”, Palmeiras, Bahia state, Brazil. Lat. 12º 30’ 31” S, Long. 41º 29’ 10” W. Sample collected by G. J. P.Ramos s/n ( HUEFS 244148) on 26 February 2017. Tetmemorus furcatus occurred in periphyton, with quiet and warm waters, associated to filamentous algae.

Notes: The main diagnostic feature of this new species is the presence of a bifurcate incision (V-shaped) in the apices. The morphologically closest taxon to the new species is Tetmemorus granulatus var. attenuatus West (1892: 132) , which differs by having apices with a closed mid incision, in addition to larger cell dimensions (4–4.6 times longer than wide). T. furcatus also has somewhat more turgid cells than the other Tetmemorus species.

Figures

FIGURES 51–65. Micrasterias jenneri var. semicirculare (51–54): ventral view (51–53), lateral view (54); Micrasterias torreyi var. pseudocurvata (55–57): ventral view (55), lateral view (56), semicell (57); Staurastrum serriforme (58–62): ventral view (58–60), apical view (61,62); Tetmemorus furcatus (63–65): ventral view (63, 64), lateral view (65). Scale bar 30 μm (51–57), 10 μm (58–65).