Metzgeria

Back in mid December I collected some Metzgeria specimens from a partially shaded, fairly dry to slightly moist granite boulder along Lake Superior in Marquette County, Michigan where I live. The forest was dominated by stunted conifers with a Quercus component. The boulder was near the edge of the woody plant dominated community. I keyed them out with only some certainty to M. furcata. The photo of the thallus at 100x is as follows:



Note this is the underside of the thallus, and the margins and midvein are pretty densely covered in trichomes, with (reproductive structures?) along the midvein. A few days later I found a dense, dark green Metzgeria mat covering the base of a densely shaded erratic boulder in a valley dominated by old-growth Tsuga/hardwoods, further down the coast from the first site and a bit further away from the lake, though the forest was particularly moist from the influence from the lake. Following is the thallus at 100x:



Note the gemmae along the margin, and the substantially smaller size of the plant overall. Also the thallus is practically devoid of hairs. This is still the underside. Here's a comparison of the two specimens at much lower magnification:



I'm still fairly new to liverwort identification, and this was my first attempt to identify Metzgeria. Does everyone agree with my ID? Are we looking at male specimens on the left and female on the right? According to Frye/Clark in Hepaticae of North America, female plants are larger and more hairy. I wasn't expecting such extreme sexual dimorphism. Also interesting is that I couldn't find any Metzgeria on tree trunks in the immediate area. Thanks for any input you can give me. -Daniel McConnell