Revision of the genus Sirodotia Kylin (Batrachospermales, Rhodophyta) with description of four new species Author Rossignolo, Natalia L. São Paulo State University, Zoology and Botany Department, Cristóvão Colombo, 2265, 15054 - 000 São José Rio Preto, São Paulo (Brazil) Author Vis, Morgan L. Ohio University, Department of Environmental and Plant Biology, OH (United States) Author Paiano, Monica O. University of Hawaï, School of Life Sciences, Honolulu, HI (United States) Author Eloranta, Pertti Sinkilätie 13, Jyväskylä FI- 40530 (Finland) Author West, John A. School of Biosciences 2, University of Melbourne, Parkville VIC 3010 (Australia) Author Ganesan, E. K. Oceanographic Institute, Universidad de Oriente, Cumaná (Venezuela) Author Yasmin, Farishta Nowgong College, Botany Department, Nagaon, 782001, Assam (India) Author Lim, Phaik-Eem Institute of Ocean and Earth Sciences (IOES), University of Malaya (Malaysia) Author Necchi, Orlando Jr São Paulo State University, Zoology and Botany Department, Cristóvão Colombo, 2265, 15054 - 000 São José Rio Preto, São Paulo (Brazil) o. necchi @ unesp. br (corresponding author) necchi@unesp.br text Cryptogamie, Algologie 2021 2021-06-04 20 8 93 127 http://dx.doi.org/10.5252/cryptogamie-algologie2021v42a8 journal article 247073 10.5252/cryptogamie-algologie2021v42a8 12297c54-d5a9-4834-8ffd-96de1009b1b1 1776-0992 7828571 Sirodotia assamica Necchi, N.L.Rossignolo, F.Yasmin, J.A.West & Ganesan ( Fig. 4 A-E) Phytotaxa 437: 125 (2020) . TYPE . — F . Yasmin, 25.II.2019 (holo-, SJRP [ SJRP 32584]). TYPE LOCALITY . — India , Assam , Nagaon District, Chapanalla; 26°19’13.7”N , 92°10’16.5”E . ADDITIONAL SPECIMENS EXAMINED. — SJRP 32583, SJRP 32585 ( Appendix 1 ). DISTRIBUTION. — Asia, India (northeastern). REPRESENTATIVE DNA SEQUENCES. — COI-5P ( MN508239 , MN508240 ) and rbc L ( MN496129 , MN496130 ). Description Plants dioecious or monoecious; whorls 400-665 µm in diameter; primary fascicles, 6-11(-12) cells; proximal cells cylindrical or ellipsoidal; distal cells obovoidal or ellipsoidal; secondary fascicles abundant, covering the entire internode; spermatangia spherical, arranged in clusters on primary or secondary fascicles, 6-8 µm in diameter; carpogonial branches straight or slightly curved, short, composed of 1-5(-6) discor barrel shaped cells; arising from periaxial cells of primary fascicles, 7-23 µm in length; carpogonia with sessile, elongate cylindrical, ellipsoidal or lageniform trichogynes, 37-64 µm in length, 10-14(-16) µm in diameter; gonimoblast initial developing from the protuberant side of the carpogonium; gonimoblast filaments with erect branches of 1-4 cells; carposporangia obovoidal, 11-14 µm in length, 6-8 µm in diameter. Remarks A distinguishing feature of Sirodotia assamica is the occurrence of spermatangia arranged in clusters, thus far not confirmed for any other species of Sirodotia . It is most closely comparable to S. delicatula based on other vegetative and reproductive characteristics and its occurrence in or near India ( Appendix 6 ). Sirodotia assamica differs from S. delicatula in having spermatangia in clusters, larger whorls (400-665 µm versus 137-433 µm in diameter), distal fascicles cells ellipsoidal or obovoid (L/D 1.3-2.1) in S. assamica and subspherical or obovoid (L/D 1.1-1.7) in S. delicatula and the known geographic distribution restricted to northeastern India .