Will H. Blackwell

Is It Kingdoms or Domains? Confusion & Solutions

Even if no other source is consulted, one may ascertain from the pages of The American Biology Teacher (ABT) that there is no universal agreement on these questions. Consider the appearance in ABT of the presentation (Margulis, 1981) of the popular five-kingdom concept, and a recent discussion favoring a system of three domains over the five-kingdom concept (Offner, 2001). Such papers have fostered additional discussion in ABT (e.g., Biermann, 2001). Also, papers in ABT have been thrown into the mix suggesting the efficacy of more than five kingdoms (Blackwell & Powell, 1995, 2001). The American Biology Teacher has thus been a significant forum for discussion of kingdom and suprakingdom concepts. Much additional debate is, of course, found in other sources as well (cf. Blackwell & Powell, 1999). The purposes of the present paper do not include repetition of a voluminous literature on the details of putative kingdom categories, but are:

THE IDENTITY AND REPRODUCTIVE STRUCTURES OF A MISPLACED SOLENOPORA (RHODOPHYCOPHYTA) FROM THE ORDOVICIAN OF SOUTHWESTERN OHIO AND EASTERN INDIANA1

A study of certain fossil, limestone‐forming algae in upper Ordovician beds (Elkhorn and Whitewater Formations of the Richmond Subseries of the Cincinnati Series) in southwestern Ohio and adjacent eastern Indiana culminated with the conclusion that an organism originally described as a sponge, and later placed in the genus Girvanella Nicholson and Etheridge (Cyanochloronta), should in fact be transferred to the genus Solenopora Dybowski (Rhodophycophyta), A calcified reproductive layer was discovered in one of the specimens sectioned. These structures are interpreted as either sporangia or as sporangial chambers, and occur in a sorus rather than a conceptacle type of arrangement. This find has an important bearing on the phylogenetic history of the Solenoporaceae.