Martha S. Calderon1,2,3,4, Fernanda Maria Marques Soares5, Danilo E. Bustamante1,3,4, Marina Sissini5, Paulo Horta5, Andrés Mansilla2,4
1Instituto de Investigación en Ingeniería Ambiental (IIIA), Facultad de Ingeniería Civil y Ambiental, Universidad Nacional Toribio Rodríguez de Mendoza, Amazonas 01001, Peru
2Laboratorio de Ecosistemas Marinos Antárticos y Sub-antárticos (LEMAS), Universidad de Magallanes, Punta Arenas, Chile
3Instituto de Investigación para el Desarrollo Sustentable de Ceja de Selva, INDES-CES, Universidad Nacional Toribio Rodríguez de Mendoza, Amazonas 01001, Peru
4Cape Horn International Center (CHIC), Puerto Williams, Chile
5Laboratory of Phycology (LAFIC), Department of Botany, Federal University of Santa Catarina, Florianópolis, Brazil
The crustose coralline algae Carlskottsbergia antarctica was proposed to encompass Melobesia verrucata var. antarctica and other specimens subsumed in the broad concept of Synarthrophyton patena from southern hemisphere (i.e. southern Chile, southern Argentina, the Falklands, and Aucklands). However, the taxonomy of the monotypic Carlskottsbergia has been based solely on morphological features, while the circumscription of S. patena have not been properly assessed in the southern hemisphere yet. Here, we studied the genus Carlskottsbergia from southern Chile, including topotype material from Cape Horn, and specimens traditionally identified as S. patena from Antarctica using anatomical observations and multilocus data (COI, psbA and rbcL). Our results indicate that C. antarctica is a species complex of multiple evolving populations. Additionality, we recognized a new lineage from Antarctic peninsula sister to C. antarctica complex containing specimens previously identified as S. patena. Our analysis strongly supported it as a distinct genus by the multilocus phylogeny and anatomical observations. This new lineage differed from C. antarctica complex by 13.1-16.7% (COI), 4.2- 6.1 % (psbA), and 7.1-8.9 % (rbcL), whereas COI, psbA, and rbcL divergences from S. patena were 12.3-13.1%, 6.9-7.1 %, and 9.8-10.3 %, respectively. Morphologically, this candidate to new genus differed from Carlskottsbergia and Synarthrophyton in the chamber size of male conceptacle, the roof thickness, and the canal diameter in the apex.