Molecular analyses reveal the presence of Corynecladia J. Agardh (Rhodophyta, Rhodomelaceae) in the Mediterranean Sea with two new species, C. millarii sp. nov. and C. mediterranea sp. nov. Author Metti, Yola Australian Institute of Botanical Science, Botanic Gardens of Sydney, 362 Narellan Rd, Mount Annan NSW 2567 (Australia) (corresponding author) yola.metti@botanicgardens.nsw.gov.au Author Furnari, Giovanni Department of Biological, Geological and Environmental Sciences, University of Catania, Via Empedocle, 58 - 95128 Catania (Italy) Author Serio, Donatella Department of Biological, Geological and Environmental Sciences, University of Catania, Via Empedocle, 58 - 95128 Catania (Italy) text Cryptogamie, Algologie 2024 2024-02-21 20 2 11 30 https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/algologie2024v45a2.pdf journal article 10.5252/cryptogamie-algologie2024v45a2 1776-0984 10698178 Corynecladia mediterranea sp. nov. ( Figs 6-8 ) Plants red-yellowish in colour, soft in texture, forming tufts up to 8 cm high; thalli terete up to 2 mm in diameter, arising from a discoid holdfast with secondary stoloniferous branches; branching irregularly alternate, usually with 2(3) orders of branches; ultimate branchlets are cylindrical-clavate; four periaxial cells per vegetative axial segment. Secondary pit-connections between cortical cells localized in middle to inner part of the cells. Cortical cells with one corps en cerise. No lenticular thickenings. Tetrasporangia in parallel arrangement cut-off abaxially from the third and fourth periaxial cells. It differs from other species of Corynecladia in showing neither secondary cortication nor starch grains in medullary cells and from genera Laurencia and Laurenciella in the occurrence of deep secondary pit connections between cortical cells. It differs from the related C. millarii mainly in different molecular sequences. FIG . 5. — Corynecladia millarii sp.nov. ,holotype CAT 2721: A , longitudinal section of a tetrasporic branch showing a tetrasporangium cut off abaxially from a fertile pericentral cell; B , transverse section of a tetrasporic branch near the apex showing the axial cell ( a ) with two sterile ( p ) and two elongate fertile ( fp ) pericentral cells; C , tetrasporangial branchlet showing parallel arrangement of tetrasporangia. Scale bars: A, B, 50 µm; C, 200 µm. TYPE MATERIAL . — Italy • Sicily , Trapani , San Vito Lo Capo , Golfo di Monte Cofano ; 38°06’21”N , 12°41’36”E ; epilithic; 0.5 m depth ; 9.VII.2017 ; D. Serio ; holotype (tetrasporophyte): CAT [ CAT 2724 ]; GenBank: OQ738971 • ibid. ; Porto Palo di Capo Passero ; 36°39’03.8”N , 15°04’37.4”E ; epilithic; 0.2 m depth ; 8.V.2021 ; D. Serio ; paratype (tetrasporophyte): CAT [ CAT 2726 ]; GenBank: OQ738950 , OQ738951 . TYPE LOCALITY . — Italy, Sicily, Trapani, San Vito Lo Capo, Golfo di Monte Cofano. ETYMOLOGY . — The specific epithet indicates the Sea in which the species was found. DISTRIBUTION . — Type locality, Golfo di Monte Cofano (Trapani, Sicily); Porto Palo di Capo Passero (Syracuse, Sicily); and probably more widely distributed. HABITAT . — Plants epilithic in upper subtidal up to 1 m depth. DESCRIPTION Plants epilithic, soft, red yellowish, up to 8 cm high, terete throughout, attached to substrate by a discoid holdfast with stolon-like branches and smaller discoid holdfasts ( Fig. 6A, B ). Erect axes, 1-2 mm in diameter in the middle portion of the thallus, irregularly alternate, usually with 2(-3) orders of branches. Epidermal cells with slight projection near the apex ( Fig. 7A ). One corp en cerise per cortical cells ( Fig. 7B ). Cortical cells showing thin secondary pit-connections. In longitudinal section they appeared localized in the middle to inner part of the cells ( Fig. 8A ). In transverse section, cortical cells quadratic to rectangular, neither radially elongated nor arranged as a palisade, measuring 25-30 ×30-35 µm in the middle portions of the plant ( Fig. 8B ). Medullary cells rounded, 40-50×35-45 µm in the middle portions of the plant, larger toward the center of the axes. Walls of medullary cells without lenticular thickenings ( Fig. 8B ). Each vegetative axial segment cuts off four periaxial cells ( Fig. 8D ). Tetrasporangial initials cut off abaxially from the third and fourth periaxial cells ( Fig. 8D ). No additional tetrasporangial periaxial cells produced. Mature tetrasporangia tetrahedrally divided, 90-100 µm in diameter. Tetrasporangia forming a parallel arrangement along the axis of the stichidium ( Fig. 8C ). Gametangia unknown.