NEW ENDOLITHIC CYANOPHYTES FROM THE NORTH ATLANTIC OCEAN. II. HYELLA GIGAS LUKAS & GOLUBIC SP. NOV. FROM THE FLORIDA CONTINENTAL MARGIN1

A new species of endolithic cyanophyte, Hyella gigas Lukas and Golubic (Order: Pleurocapsales), differs from other species of Hyella by its larger cell and filament dimensions and its laminated, often pigmented sheath. It bores into mollusk shells and other marine carbonate substrates on the east coast of North America, the Bahama Islands and the Northern Mediterranean Sea, where it is found from near mean low water down to 25 m depth. This comparatively shallow maximum depth is probably due to the limited capacity of Hyella gigas to adapt to changing light quality and intensity. We reject the suppression of the genus Hyella as proposed by Drouet and Daily.     

NEW ENDOLITHIC CYANOPHYTES FROM THE NORTH ATLANTIC OCEAN. III. HYELLA PYXIS LUKAS & HOFFMAN SP. NOV.1

A new species of marine endolithic cyanophyte, Hyella pyxis Lukas and Hoffman (Order: Pleurocapsales), differs from other species of Hyella in its cell and filament dimensions, the manner in which its branches are initiated and the presence of gloeocapsin in the sheaths of colonies from the intertidal zone. Hyella pyxis colonies consist of a small cluster of coccoid cells located at the substrate surface and long, conspicuously branched filaments composed of cells that are longer than they are wide. Branches are initiated by the reorientation of the distal end of a filament cell or by the elongation of a filament cell, usually at one of its distal corners. Chromatic adaptation was not observed perhaps accounting for the relatively shallow depth limit of this species. Hyella pyxis was found within mollusk shells from the continental margin of eastern Florida to a depth of 50 m and carbonate rocks in the intertidal zone on Bermuda.     

NEW ENDOLITHIC CYANOPHYTES FROM THE NORTH ATLANTIC OCEAN: I. CYANOSACCUS PIRIFORMIS GEN. ET SP. NOV.1

This paper describes a new genus and species of endolithic microorganism, Cyanosaccus piriformis Lukas and Golubic (Cyanophyta, Pleurocapsales). It is characterized by 1) having one to four spherical to pear-shaped cells within a stalked, gelatinous sheath, 2) its mode of reproduction by release of a large number of baeocytes produced by the proximal daughter cell following transverse binary fission of the parent cell, and 3) its ability to bore into and dwell within carbonate substrates in the marine environment. Its habit of asymmetrical sheath production allies it with the common microboring genera Hyella and Solentia within the family Hyellaceae. Cyanosaccus is a common inhabitant of mollusk shells found in water depths ranging from +0.5 to –75 m MLW on the eastern Florida continental margin and in carbonate sands or rocks in the intertidal and subtidal zones of the Bermuda and Bahama Islands. Its distribution within and among inhabited substrates is patchy due to its mode of reproduction and growth.