Simple thalloid II
Riccardia (photo by L. Zhang) |
Aneura pinguis (photo by L. Zhang) |
This lineage is composed of many of the taxa that are classified within the Metzgeriales (Aneuraceae, Makinoaceae, and Metzgeriaceae) and the Pleuroziaceae. It is in this clade where the majority of simple thalloid species diversity is found. A detailed phylogeny of the group is shown in Figure 7 (modified from Forrest et al., 2006).
| Figure 7. Simple thalloid clade II (based on the topology from the 5 partition Bayesian analysis of 5 loci including chloroplast, nuclear, and mitochondrial DNA). |
All members of the Simple thalloid II clade have lenticular apical cells. All of the taxa excluding Pleurozia possess nearly “neckless” archegonia, which is diagnostic of that clade. The Aneuraceae and Verdoornia are united by antheridia and archegonia which are sunken in pits and surrounded by tubular outgrowths of thallus (shoot perigynia); while the Metzgeriaceae are defined by thalli with midribs and wings, gametangia on ventral branchlets; antheridia in inrolled sacs, and archegonia under thallus flaps (“involucre”).
Pleurozia acinosa (photo by L. Zhang) |
Cryptothallus mirabilis (photo by Michael Lüth; British Bryological Society Image Gallery) |
Pleurozia, formerly classified in the leafy liverworts, was unexpected as a member of this clade, but the relationship is well supported (see Phylogeny).
Cryptothallus (Aneuraceae), a unique and strange simple thalloid liverwort, is non photosynthetic, subterranean, and completely parasitic on mycorrhizal fungi.
Haplomitriaceae and Treubiaceae
Complex Thalloids and the Blasiaceae
Simple thalloids I
Simple thalloids II plus the Pleuroziaceae
Leafy I
Leafy II
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