Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera) Author Ward, Philip S. Author Blaimer, Bonnie B. text Zoological Journal of the Linnean Society 2022 194 893 937 journal article 10.1093/zoolinnean/zlab047 0024-4082 10115063 6144DD31-0F7B-4589-86A3-F40994452C9 CREMATOGASTER ROSSI BUREN, 1968 , STAT. REV. Crematogaster rossi Buren, 1968: 111 . Holotype worker, San Jose del Cabo , Baja California Sur , Mexico (USNM) ( USNMENT00531965 ) (examined). Junior synonym of C. vermiculata : Morgan & Mackay, 2017: 396 ; here overturned. Worker measurements ( N = 6): HW 0.90–1.1, HL 0.83– 1.04, SL 0.76–0.86, WL 0.95–1.25, MtFL 0.80–0.99, MSC 0–8, A4SC 25–34, PP-SL/HW 0.15–0.19, CI 1.06– 1.13, OI 0.25–0.27, SI 0.78–0.85, MtFL/HW 0.87–0.92, SPL/HW 0.24–0.26, SPTD/HW 0.53–0.60. Discussion: Phylogenomic (UCE) data reveal a close relationship of C. rossi to C.californica and C. opuntiae ; it has no close affinity to C. vermiculata ( Fig. 1 ). Crematogaster rossi is recognizable by the combination of a predominantly shiny head, conspicuously rugulose promesonotum on a reticulate-foveolate background and abundant standing pilosity on the gaster. The mesosomal sculpture is superficially similar to that of C. vermiculata , but the two species differ in numerous ways. Crematogaster rossi is larger (HW 0.90–1.10, WL 0.95–1.25), with disproportionately longer scapes (SI 0.78–0.85) and legs (MtFL/HW 0.87–0.92) and with propodeal spines that are straight, longer and more divergent posteriorly (SPL/WL 0.22–0.24, SPTD/HW 0.53–0.60) (compare with equivalent measurements for C. vermiculata below). There are up to two isolated standing hairs on each pronotal humerus and usually a few short standing hairs on the mesonotal declivity (MSC 0–7), but the pilosity on the gaster is particularly well-developed (A4SC 25–34, compared with A4SC 9–20 in C. vermiculata ). From the closely related species, C. californica and C. opuntiae , C. rossi can be distinguished primarily by its promesonotal sculpture and abundant standing pilosity on the gaster. Distribution and biology: Crematogaster rossi is known from the Mexican states of Baja California Sur and Baja California , and (more doubtfully) Nayarit . Specimens with habitat information come from ‘oak woodland’ and ‘dry wash next to oak woodland’ but others have been collected from sites in more xeric locations. The species is apparently a ground-nester.