Article: The Devonian genus Keega (Algae) reinterpreted as a stromatoporoid basal layer

The Upper Devonian genus Keega Wray, originally described as an alga related to the crustose Corallinaceae, is reinterpreted to be the structurally modified base, here termed basal layer, of a laminar form of the stromatoporoid Stachyodes Bargatzky. Besides altering the status of Keega and its significance for the phytogeny of crustose coralline algae this conclusion also implies that Stachyodes adopted a laminar as well as the more common dendroid form and it supports the view that the primary internal structure of Stachyodes is cellular or microreticulate. 'Tubulated' or 'striated' microstructure, common in Stachyodes. is regarded as a product of diagenetic alteration. Basal layers are present in at least two other genera of laminar stromatoporoids and are interpreted to be a morphological adaptation facilitating horizontal as well as vertical growth in laminar forms. Type-material of Keega is compared with specimens from Alberta, Canada, and K. australe is emended and transferred lo Stachyodes.