Micrasterias levergerensis W.F.O.Duarte-dos-Santos & C.E.M.Bicudo

Santos, Waléria Finícia De Oliveira Duarte Dos & Bicudo, Carlos Eduardo De Mattos, 2023, Micrasterias levergerensis sp. nov. (Desmidiaceae, Zygnematophyceae), a new species from the Pantanal of Mato Grosso State, Brazil, Phytotaxa 626 (3), pp. 219-222 : 220-221

Micrasterias levergerensis W.F.O.Duarte-dos-Santos & C.E.M.Bicudo sp. nov. ( Figs. 1–2 )

Description: Cell approximately circular, semicell 5-lobed, polar lobe broadly cuneate, lateral margins straight, apex slightly retuse at the middle, apical margin with small irregularly disposed spines, lateral and basal lobes equal size, 2-furcate, incision little deep between 1 st order lobules, incision shallow between 2 nd order lobules, 2 nd order lobules ending in small spines, the external usually a little longer than the internal ones, chloroplast with prominent lamellae along the between lobes incisions, pyrenoids various chaotically distributed along the plastid, cell wall colorless to light brown. Cell measurements: length 80–92 µm, maximum breadth 79.8–85 µm, breadth of polar lobe 28.5–33.4 µm, breadth of isthmus 17–20.1 µm.

Type: BRAZIL. Mato Grosso: Município de Santo Antônio do Leverger, Pantanal , pond, 56°06’27.0” W, 15°48’14.8” S, 02 October 2017, N.D. da Silva Paes s.n. (holotype: Algae collection sample UFMT 651 ) .

Etymology: The epithet is an adjective related to Santo Antônio do Leverger, the locality from which the type-material was collected.

Habitat: metaphyton.

Population studied was very homogeneous, with almost no form variation detected. The polar lobe broadly cuneate with straight lateral margins and a slightly retuse apex in the middle, with irregularly distributed small spines are diagnostic for this species. Micrasterias levergerensis morphologically resembles M. tetraptera West & G.S. West (1898: 296) and M. papillifera Brébisson ex Ralfs (1848: 72) var. papillifera f. papillifera , but differs mainly in its straight polar lobe lateral margins. Furthermore, M. tetraptera representative specimens are larger, and the cell length to breadth ratio as well as the polar lobe breadth of M. papillifera var. papillifera f. papillifera are greater.

Present M. levergerensis must also be compared with Micrasterias papillifera Brébisson ex Ralfs var. verrucosa Schmidle (1896: 23) (today a synonym for the typical Micrasterias papillifera ), from which differ by having slightly larger cells, but mostly in its cell wall smooth, not granulate with a series of c. 5 supra isthmial larger granules.

Figures

FIGURES 1–2. Micrasterias levergerensis W.F.O.Duarte-dos-Santos & C.E.M.Bicudo, sp. nov. (Fig. 1, photomicrograph by W.F.O. Duarte-dos-Santos). Scale bars = 10 µm.