Sirodotia Kylin, 1912

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 : 100-101

Sirodotia Kylin

Nova acta Regiae Societatis Scientiarum Upsaliensis, ser. IV, 3: 38 ( Kylin 1912).

Section Sirodotia (Kylin) Necchi & Entwisle, Phycologia 29, 4: 485 (Necchi & Entwisle 1990).

TYPE SPECIES. — Sirodotia suecica Kylin , Nova acta Regiae Societatis Scientiarum Upsaliensis Ser. IV, 3: 38 (1912).

DISTRIBUTION. — The genus has been collected in temperate, tropical, subtropical and sub-polar regions of North and South America, Africa, Asia, Australasia and Europe.

Revised description

Plants monoecious, dioecious or polyoecious, bluish green to yellowish green; branching irregular; whorls well-developed or reduced, contiguous or separated, obconical or pear-shaped; cortical filaments of the main axis well-developed, one or two layers; primary fascicles with cells variable in shape, cylindrical, ellipsoidal, obovoid, subspherical or spherical; secondary fascicles abundant, covering the entire or two-thirds of internode, equal to or less than the length of the primary fascicles; spermatangia spherical, subspherical or obovoid on primary or secondary fascicles; carpogonial branches well-differentiated from the fascicles, straight, rarely curved, developing from the periaxial, proximal, median and distal cells of primary fascicles or cortical filaments, rarely on the secondary fascicles, short, composed of disc- or barrel-shaped cells; involucral filaments few and short, composed 1-4 cylindrical or ellipsoidal cells; carpogonia asymmetrical, with a hemispherical protuberance in the basal portion; trichogynes sessile and cylindrical, cylindrical-elongated, conical-elongated, clavate, fusiform, lageniform or ellipsoidal, with or without wavy margins; carposporophyte diffuse extending along the internode; gonimoblast filaments develop on the same side or opposite side of the basal protuberance of the carpogonium; gonimoblast filaments prostrate and indeterminate, composed of 1-5 cylindrical cells, producing short, erect branches, formed by cylindrical or ellipsoidal cells, with terminal or sub-terminal carposporangia; carposporangia large or small, obovoidal, ellipsoidal or subspherical.

Diagnostic characters

The genus is characterized by diffuse carposporophytes composed of prostrate gonimoblast filaments producing short, erect filaments with terminal carposporangia; and asymmetric carpogonium, with a semi-spherical basal protuberance; the shape of the whorls (obconical or pear-shaped) can be used as a complementary character; however, it is not exclusive to the genus and can be observed in species of Kumanoa (Necchi & Vis 2012) , Paludicola ( Vis et al. 2020) and to varying degrees in other genera of Batrachospermales .

KEY TO THE SPECIES OF THE GENUS SiRodoTia KYLIN

1. Carposporangia small, 5-10 µm in length..................................................................................................... 2

— Carposporangia large, 10-21 µm in length ................................................................................................... 3

2. Primary fascicle 3-5 cells; erect gonimoblast filaments with 1 cell .................................................................... ................................................................................................ S. kennedyi A.L.Szinte, J.C.Taylor & M.L.Vis

— Primary fascicle (5-)6-10 cells; erect gonimoblast filaments with 2-4 cells........................................................ ....................................................................................... S. huillensis (Welwitsch ex West & G.S.West) Skuja

3. Spermatangia arranged in clusters........... S. assamica Necchi, N.L.Rossignolo, F.Yasmin, J.A.West & Ganesan

— Spermatangia isolated or in groups of 2-3..................................................................................................... 4

4. Gonimoblast initial developing from the non-protuberant side of the carpogonium................ S. suecica Kylin

— Gonimoblast initial developing from the protuberant side of the carpogonium ............................................ 5

5. Known distribution restricted to Asia ( Indonesia, Japan and Malaysia) ............................... S. delicatula Skuja

— Known distribution in the Americas............................................................................................................. 6

6. Carposporangia wide, 8-13 µm in diameter..................................................................................................... ................................................................................................... S. amazonica sp. nov. and S. cryptica sp. nov

— Carposporangia narrow, 6-8.5 (-9.5) µm in diameter ................................................................................... 7

7. Known distribution in southern North America ( Costa Rica) and South America ( Brazil) .............................. ................................................................................................................................ S. delicatuliformis sp. nov.

— Known distribution in arid regions of North America ( United States, Mexico) ............................................... ............................................................................................................................. S. aquiloamericana sp. nov.