Myrmica incompleta Provancher, 1881

Shattuck, Steve & Cover, Stefan, 2016, Taxonomy of some little-understood North American ants (Hymenoptera: Formicidae), Zootaxa 4175 (1), pp. 10-22 : 18-19

Myrmica incompleta Provancher, 1881

Myrmica incompleta Provancher, 1881: 359 . Syntype worker, Cap-Rouge [46°46′N 71°21′W], Quebec (probably, specific details lacking) (Provancher) (Museo Civico di Storia Naturale, Genoa) [https:// www.antweb.org/specimen/CASENT0905772].

Myrmica brevinodis var. frigida Wheeler, 1917: 502 . Syntype workers, Ice River Valley , British Columbia, 5000ft. (Whymper) (Musee d'Histoire Naturelle Genève; Museo Civico di Storia Naturale, Genoa) [https:// www.antweb.org/specimen/CASENT0904082, https://www.antweb.org/specimen/CASENT0907634]. New synonym.

Myrmica brevinodis whymperi Forel, 1913: 215 . Syntype workers, Vermillion Pass [51°14′N 116°03′W], Alberta ; near Field [51°24′N 116°29′W], British Columbia ; near Lake Louise , British Columbia [51°26′N 116°11′W] (Whymper) (Musee d'Histoire Naturelle Genève; Museo Civico di Storia Naturale, Genoa) [https:// www.antweb.org/specimen/CASENT0907635; https://www.antweb.org/specimen/CASENT0904080]. New synonym.

Myrmica brevinodis var. sulcinodoides Wheeler, 1917: 502 . Syntype workers, South Dakota, Utah, Maine (no specific localities given) (Museo Civico di Storia Naturale, Genoa) [https://www.antweb.org/specimen/ CASENT0904081 from Park City, Utah possible type specimen]. New synonym.

The taxonomic history of the forms centering on what is presently called Myrmica incompleta Provancher is a saga calculated to make the wicked laugh and the judicious weep. While contemplating this tangle, keep in mind that M. incompleta is a common ant in cold climates across Canada and the northern United States, from the Maritime Provinces west to Alaska, south to New England and the Great Lakes region, and with an enormous southern extension in the Rocky Mountains , Washington , Oregon, and the Sierra Nevada in California. Over this vast expanse its ecology and colony structure seem to be pretty consistent. It is an ant of moist, open or semi-open habitats, often forming dense populations at the edges of bogs, fens, and wet depressions in meadows. Colonies can be very large, are usually highly polygynous, and appear at times to form large, unicolonial populations. The workers vary in size more than in most Myrmica both within and between colonies, and show variation in sculpturing, propodeal spine length, and color.

Because the ant is commonly collected, its variability attracted the attention of early ant taxonomists who, following the conventions of their times, named whatever variants they came across. The result was a jumble of taxon names based on small variations in color or sculpture. After much work by Creighton (1950) and Francoeur and Beique (1966), the complex is presently arranged as follows:

Myrmica incompleta Provancher, 1881

= Myrmica rubra brevinodis Emery, 1895 = Myrmica rubra canadensis Wheeler, 1916 = Myrmica rubra subalpina Wheeler, 1917

Myrmica whymperi Forel, 1913

= Myrmica brevinodis sulcinodoides Wheeler, 1917 = Myrmica rubra frigida Wheeler, 1917

Our concern here is with the name Myrmica whymperi Forel , which is still valid. The name was established as a variety of M. brevinodis by Forel (1913) but only a few years later Wheeler (1917) synonymized it with M. sulcinodoides . Creighton (1950) considered this complex and found that “… it is necessary to synonymize the varieties canadensis, frigida , subalpina, sulcinodoides and whymperi with brevinodis …” as the material he examined had shown “…the impossibility of satisfactory separation on either a structural or a distributional basis. In every case the structural distinctions involved consist of exceedingly slight differences in sculpture, pilosity or color.” Thus M. whymperi fell into synonymy with M. brevinodis . Unfortunately, Creighton’s perspicacity in this matter was not emulated by his successors. The next year Smith (1951), without comment, removed M. sulcinodoides from synonymy and placed it as a subspecies of M. brevinodis . He also transferred M. frigida and M. whymperi from synonymy with M. brevinodis to synonymy with M. brevinodis sulcinodoides . Francoeur & Beique (1966), while examining the type material of Provancher, realized that what Creighton (1950) had thought was M. brevinodis was actually Provancher’s M. incompleta . As a result M. brevinodis fell into synonymy with M. incompleta and M. frigida and M. whymperi became synonyms of M. incompleta sulcinodoides rather than M. brevinodis sulcinodoides . Mackay, Lowrie et al. (1988) treat M. sulcinodoides as a full species in their identification key although no discussion is given and no mention was made of how its synonyms should be treated. M. incompleta and M. whymperi (as M. sulcinodoides ) are separated based on sculpture and color. Finally, Bolton (1995) recognized that while the name sulcinodoides had been used as the valid name for this taxon, in fact whymperi was the older name and had priority. Thus we arrived at the arrangement listed above.

After examining numerous specimens from throughout the range of M. incompleta , and a syntype of M. whymperi present in the MCZC, we are certain that Creighton (1950) was correct. All of the taxa listed above are best regarded as variants of a single geographically widespread species. This includes M. whymperi . The syntype worker has slightly stronger sculpturing and longer propodeal spines than most examples of M. incompleta , but specimens with similar attributes are occasionally found in populations far from the M. whymperi type locality. In the absence of additional support for the significance of such differences, there is no reason at present to maintain M. whymperi as a distinct species in its own right.

Myrmica incompleta is known from southern Canada and the United States from Alaska and from California and Arizona north and east through Colorado, South Dakota and Illinois to Maine. It is the host for the xenobiotic social parasite Formicoxenus provancheri .