The abstract of the paper says it best:

Comparisons of ITS and LSU rDNA sequences from ectomycorrhizal root tips and ascomata of specimens identified as Helvella lacunosa from North America, Europe and Asia revealed that the taxa from western North America and Mexico formed a well supported clade different from the eastern North American, European and Asian taxa. Within this western North American clade there are at least four taxa. Here we describe two of these western taxa as new species: Helvella vespertina and Helvella dryophila. Helvella vespertina is a bigger version of H. lacunosa, is variable in hymenial color and shape and forms ectomycorrhizae with conifers; it fruits typically Oct–Jan. Helvella dryophila is characterized by a dark almost black, squat pileus, a light stipe when young, medium size and forms ectomycorrhizae with Quercus species; it fruits Jan–Jun. Due to insufficient material, the two other Helvella taxa are discussed but not formally described here.

What about those two other undescribed North American taxa that we must continue to call Helvella lacunosa? Nguyen et al. describe one as a well-supported clade from "northern Sierra Nevada of California and Cascades of Oregon" that probably contains two species, while the other is strictly Mexican in distribution and probably contains 4 undescribed species. H. vesperina and H. dryophila seem to be restricted to the Pacific northwest, California coast ranges, and Sierra foothills, so mushrooms from elsewhere should probably still be called Helvella lacunosa. Coastal Californians can best separate their elfin saddles by the host tree.

So, what taxa to choose:

• If your elfin saddle was outside of the Pacific coast of North America or the Pacific Northwest region, continue using Helvella lacunosa
• Otherwise...