Janet Leonard and John Pearse gave a presentation on banana slug biology.
Ariolimax californicus, brachyphallus and dolichophallus are all found on the San Francisco peninsula.
The cladogram based on mitochondrial 16S sequences shows short branches (speciate very quickly). There are three known clades of dolichophallus (morphologically distinct, molecularly indistinct). There strong differences in morphology and behavior between species but very similar molecularly. Evidence from the molecular work points to rapid evolution, possibly driven by sexual selection. Their ploidy is unknown but most likely the same across species.