Melanothamnus macaronesicus Rodríguez-Buján & Díaz-Tapia, 2021

Rodríguez-Buján, Iván, Pimentel, Manuel & Díaz-Tapia, Pilar, 2021, Melanothamnus macaronesicus Rodríguez-Buján & Díaz-Tapia, sp. nov. (Rhodomelaceae, Rhodophyta): a new turf-forming species from the Azores and the Canary Islands, Cryptogamie, Algologie 20 (7), pp. 77-91 : 81

Melanothamnus macaronesicus Rodríguez-Buján & Díaz-Tapia , sp. nov.

( Figs 3; 4)

DIAGNOSIS. — Thalli up to 2.5 cm in height, forming dense turfs composed of decumbent axes that produce extensive prostrate systems. Axes with four pericentral cells, ecorticate. Erect axes 130-200 µm in basal parts, with exogenous branches that replace trichoblasts, alternately or pseudodichotomously branched. Trichoblasts short, simple or once branched, formed on every segment. Spermatangial branches growing on the first dichotomy of fertile trichoblasts, with 1-2 apical sterile cells at maturity. Cystocarps globose. Fertile parts of tetrasporangial branches bifurcated or bearing alternate branches, with tetrasporangia forming markedly spiral series. rbc L sequence of the holotype: MW567802.

HOLOTYPE. — SANT 33663 (male and female gametophytes, tetrasporophytes).

ADDITIONAL STUDIED SPECIMENS. — PD 4116 (sterile), PD 4121 (tetrasporophytes), PD 4129 (sterile), PD 4130 (tetrasporophytes),

Puerto del Carmen, Lanzarote, Canary Islands, Spain; PD3692 (sterile), Praia do Populo , São Miguel, Azores, Portugal ; PD3843 (sterile) , PD3847 (sterile), Praia San Roque , São Miguel, Azores, Portugal .

TYPE LOCALITY. — Puerto del Carmen, Lanzarote, Spain.

ETYMOLOGY. — “ macaronesicus ” refers to the name of the region where the species was found.

HABITAT AND DISTRIBUTION. — Melanothamnus macaronesicus Rodríguez-Buján & Díaz-Tapia , sp. nov. was collected from turfs mixed with other small species in intertidal sand-covered rocks from the Azores and the Canary Islands.