Sirodotia amazonica Necchi, N.L.Rossignolo & M.O.Paiano, 2021

Rossignolo, Natalia L., Vis, Morgan L., Paiano, Monica O., Eloranta, Pertti, West, John A., Ganesan, E. K., Yasmin, Farishta, Lim, Phaik-Eem & Necchi, Orlando Jr, 2021, Revision of the genus Sirodotia Kylin (Batrachospermales, Rhodophyta) with description of four new species, Cryptogamie, Algologie 20 (8), pp. 93-127 : 101

Sirodotia amazonica Necchi, N.L.Rossignolo & M.O.Paiano , sp. nov.

( Fig. 3 A-E)

TYPE. — O. Necchi Jr., 27.IX.2010, (holo-, SJRP [ SJRP 31924 ]).

TYPE LOCALITY. — Brazil, Mato Grosso, River Rosana, Route BR- 163 , between Sinop and Sorriso; 11°57’26”S, 55°31’01”W.

ADDITIONAL SPECIMENS EXAMINED. — SJRP 32139, SJRP 32140, SJRP 32576, SJRP 32577, and SJRP 32578 ( Appendix 1).

ETYMOLOGY. — The species epithet indicates that the alga occurs in the Amazonian region in Brazil.

DISTRIBUTION. — South America: Brazil (mid-western and northern Brazil).

REPRESENTATIVE DNA SEQUENCES. — COI-5P ( KF010489 , KF010490 , MW053464 ), rbc L ( KC951866 , KC951867 , MW053480 ) and LSU (BR14, BR15, MW053499 ).

Description

Plants monoecious or dioecious; whorls 249-491 µm in diameter; primary fascicles, 4-8 cells; proximal cells cylindrical or ellipsoidal; distal cells spherical, subspherical, obovoidal or ellipsoidal; secondary fascicles abundant, covering the entire internode; spermatangia spherical or obovoidal, 1-3 in a group, few or abundant on primary or secondary fascicles, 6-9 µm in diameter; carpogonial branches composed of 1-4 disc- or barrel shaped cells, arising from periaxial or proximal cells of primary fascicles, rarely on the secondary fascicles or cortical filaments, short, 8.5-25 µm in length; carpogonia with sessile, elongate cylindrical (with wave margins) or fusiform trichogynes, 35-58(-62) µm in length, 8-14(-15) µm in diameter; gonimoblast initial developing from the protuberant side of the carpogonium; gonimoblast filaments prostrate with erect branches of 1-4 cells; carposporangia obovoidal or subspherical, 10-18(-19) µm in length, (7-)8-13 µm in diameter.

Remarks

The phylogeography study by Paiano & Necchi (2013) showed the existence of two cryptic species in Brazil. No morphological characteristics were observed to distinguish them, but a high interspecific divergence (2.3-3.0% for rbc L and 4.4-6.2% COI-5P). We conclude they are distinct. Sirodotia amazonica Necchi, N.L.Rossignolo & M.O.Paiano, sp. nov. is very similar to two species found in Brazil, S. delicatuliformis Necchi, N.L.Rossignolo & M.O.Paiano , sp. nov. and S. cryptica Necchi, N.L.Rossignolo & M.O.Paiano , sp. nov., overlapping for most morphometric and morphological characters. However, S. amazonica Necchi, N.L.Rossignolo & M.O.Paiano , sp. nov. is distinguishable from S. delicatuliformis sp. nov. based on the wider carposporangia (8-13 versus 6-8.5(-9.5) µm in diameter).

Figures

FIG. 3. – Morphological features of Sirodotia species: A-E, Sirodotia amazonica Necchi, N.L.Rossignolo & M.O.Paiano, sp. nov. (all figures taken from sample SJRP 31924 - holotype): A, pear-shaped whorls; B, primary fascicle with spermatangia (arrow); C, carpogonium with a mature trichogyne (arrowhead) showing the basal hemispherical protuberance (double arrow) and attached spermatia (arrow); D, fertilized carpogonium with a cylindrical trichogyne (arrowhead), attached spermatia (arrow) and gonimoblast initial developing from the protuberant side of the carpogonial base (double arrow); E, carposporangia (arrow) and erect (arrowhead) gonimoblast filaments. F-J. Sirodotia aquiloamericana: F, pear-shaped whorls; G, primary fascicle with spermatangia (arrow); H, carpo- gonium with a mature trichogyne (arrow) showing the basal hemispherical protuberance (arrowhead); I, fertilized carpogonium with a cylindrical trichogyne (arrowhead), attached spermatia (arrow) and gonimoblast initial developing from the protuberant side of the carpogonial base (double arrow); J, carposporangia (arrow) and erect (arrowhead) gonimoblast filaments. K, Sirodotia assamica Necchi, N.L.Rossignolo, F.Yasmin, J.A.West & Ganesan (photo taken from sample SJRP 32583): pear-shaped whorls showing densely arranged spermatangia (arrows). Scale bars: A, F, K, 200 μm; B, G, J, 20 μm; C-E, H, I, 10 μm. H-I, redrawn from Necchi et al. (1993).