Metapeyssonnelia milleporoides, a new species of coral-killing red alga (Peyssonneliaceae) from Puerto Rico, Caribbean Sea

Metapeyssonnelia milleporoides is newly described based on specimens growing epizoically on corals, primarily Millepora complanata and Porites sp., in shallow-water coral reef environments off Puerto Rico. The new species possesses light hypobasal calcification, sunken tetrasporangial nemathecia and has hypothallial cells arranged in broad flabellules. Both cystoliths and hair cells are present in the perithallus. The species grows sympatrically with M. corallipeda and also kills its host by overgrowth. Peyssonnelia dawsonii is recognized as a member of Metapeyssonnelia and is transferred to this genus.