Formica obscuriventris Mayr, 1870

Shattuck, Steve & Cover, Stefan, 2016, Taxonomy of some little-understood North American ants (Hymenoptera: Formicidae), Zootaxa 4175 (1), pp. 10-22 : 16-17

Formica obscuriventris Mayr, 1870

Formica truncicola obscuriventris Mayr, 1870: 951 . Syntype workers, Connecticut (specific locality not given) (Norton) (Naturhistorisches Museum Wien, Vienna; Berlin Museum für Naturkunde der Humboldt- Universität) [https://www.antweb.org/specimen/ CASENT0915637, https://www.antweb.org/specimen/ FOCOL 2745 ].

Formica rufa clivia Creighton, 1940: 8 . Holotype and paratype workers, Fish Creek Ranger Station, Glacier National Park [48°33′N 113°59′W], Montana, 8-12 July 1934 (W.S. Creighton) (American Museum of Natural History, Field Museum of Natural History) [https://www.antweb.org/specimen/FMNHINS0000062712].

To say that North American ants of the Formica rufa species group have had a troubled taxonomic history is to indulge in a talent for understatement. In the late 19th and early 20th century, numerous names were generated by early taxonomists, with little reference to ecology, distributional data, comparative context, or sense. To be fair, most of these early workers were dealing with very limited material. Creighton (1940, 1950) was the first to attempt to make sense of the resulting hodgepodge of names. Since then, some infraspecfiic taxa have proven to be valid species, others have been synonymized, but a few problematic names remain.

Formica clivia was described as a subspecies of F. r u f a ( Creighton, 1940) and transferred to F. obscuriventris by Creighton (1950). Creighton delimited the subspecies based on color and pilosity and claimed distributional support: F. obscuriventris being primarily eastern, with a few high altitude populations in the southern Rockies; F. clivia being primarily western and being present at lower altitudes in the Rockies. An examination of material from over the entire enormous range of F. obscuriventris provides little support for Creighton’s scheme. Eastern populations vary in color, but do not show the deep infuscation present in some western populations. Colonies with heavily infuscated workers occur throughout much of the American west, but the infuscation is variable and colonies with little or no infuscation are not infrequently encountered. Pilosity in this species is notably variable, but it doesn’t seem to co-vary with color as Creighton thought. As such, there is little evidence to justify the maintenance of F. clivia as separate from F. obscuriventris . For these reasons, F. clivia is here synonymized with F. obscuriventris .

Formica obscuriventris is known from Canada (all southern provinces) and the United States (north from Oregon, Nevada, Utah, Colorado, South Dakota, Tennessee and Georgia) .