| | ||||||
| | | | | | | |
| CONVENTIONAL (all characters with equal weight) |
DEVELOPMENTAL (discrete independent characters are in bold print) |
| Evanescent wall | A layer originating as part of a spore wall (sloughing) which when intact may be either homogenous or consist of sublayers |
| Laminated wall | A single layer which originating as part of a spore wall which forms sublayers as it grows in thickness |
| Unit wall | A single layer originating as part of a spore wall (permanent) |
| Germinal wall | A thin inner layer of a spore wall only in Gigaspora which forms a warty surface prior to germination |
| Membranous wall | A single thin hyaline layer originating as part of a spore wall (one character) or as part of a separate flexible germinal wall (another character) |
| Coriaceous wall | A thicker hyaline layer originating as part of a flexible germinal wall |
| Amorphous wall | A plastic hyaline layer originating as part of a flexible germinal wall |
| Beaded wall | A thin outer layer with surface excrescences which originates as part of a flexible germinal wall |
As seen in the above table, all of the conventional characters heretofore described as discrete and independent parts of a spore are actually parts of only two independent components: (1) a spore wall and (2) one or more flexible inner walls which functioned historically or contemporarily in germination (hence the term "germinal walls"). Within each of these two components are layers, and each layer may have its own unique phenotype. The important point here is that layers and their properties are parts of a character complex and thus are interdependent rather than independent--which makes a BIG difference when attempting to interpret morphology within an evolutionary context and to define where and to what extent any of these parts can produce new variation (hence new taxa).