Sirenicapillaria rigida D.E. Berthold, Lefler & Laughinghouse sp. nov.

Figs 7–15

DESCRIPTION: Thallus dark brown, tangled, web-like. Filaments straight and rigid, 5 cm long, 28–83(–94) µm wide with thick, lamellate hyaline sheath. Trichomes cylindrical, 22.8–63.3 µm wide, thicker in the middle and gradually attenuated towards apices. Cells slightly constricted at cross walls. Cells discoid, wider than long, 1.8–3.9 µm long. Cell content light to dark brown, with pigmentless cells towards apices. Apical cell rounded, at times conical, with occasional calyptra. Reproduction by release of individual cells, straight or diagonal trichome fragmentation, necridia, hormogonia.

COMMENT: Individual filaments observed with naked eye and reminiscent of the freshwater Microseira wollei . Hormogonia form attached clumps on individual filaments.

TYPE LOCALITY: USA. Florida: Duck Key (24°46.635 ʹ N, 80°54.527 ʹ W).

HABITAT: Benthic, wrapped around seagrasses in marine coasts.

ETYMOLOGY: Latin adjective rigidus, -a, -um, in reference to the physical rigidity of the filaments.

HOLOTYPE: US 227691 (dried material in a metabolically inactive state of reference strain BLCC-M116), deposited in US National Herbarium, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.

REFERENCE STRAIN: BLCC-M 116.

MATERIALS ANALYSED: BLCC-M 116 (US 227691), BLCC-M 134 (US 227777).