Genus Leptothorax Mayr

Most species formerly placed in this genus have been reassigned to Nesomyrmex and Temnothorax, leaving Leptothorax much more narrowly and precisely circumscribed (Bolton 2003). Nevertheless, the species­level taxonomy of the North American Leptothorax remains in a state of chaos. There are at least two species in California: one can be easily identified as L. calderoni (see “Taxonomic Changes” above), while the remaining collec­tions—here assigned the code name Leptothorax sp. CA­01—cannot be identified with certainty. They belong to the muscorum ­complex, which is widespread in temperate North America and Eurasia, and within which species limits are ill­defined. References: Bolton (2003), Brown (1955a), Buschinger and Heinze (1993), Cole (1954d), Creighton (1950a), Douwes and Stille (1987), Francoeur (1986b), Francoeur et al. (1985), Heinze (1989b, 1991, 1998), Heinze et al. (1996), Loiselle et al. (1990), Möglich (1979).