Crematogaster browni, BUREN, 1968

CREMATOGASTER BROWNI BUREN, 1968 View in CoL , STAT. REV.

( FIGS 10A View Figures 3–12 , 29 View Figures 25–30 )

Crematogaster browni Buren, 1968: 100 View in CoL .

Holotype worker, Garden Canyon , Huachuca Mts., Arizona (W. S. Creighton) ( LACM) (examined) .

Junior synonym of C. cerasi: Morgan & Mackay, 2017: 91 ; here overturned.

Worker measurements (N = 16): HW 0.69–1.01, HL

0.67–0.94, SL 0.57–0.75, WL 0.74–1.08, MtFL 0.60– 0.84, MSC 2–9, A4SC 14–30, PP-SL /HW 0.19–0.25, CI 0.98–1.09, OI 0.22–0.25, SI 0.75–0.85, MtFL /HW 0.84–0.89, SPL/HW 0.18–0.24, SPTD/HW 0.44–0.53.

Discussion: Neither morphological nor molecular evidence supports the synonymy of C. browni under C. cerasi . The phylogenomic UCE results show that these two species are not sister-taxa; C. browni is more closely related to C. emeryana , C. lineolata and C. punctulata , while C. cerasi is the sister-species of C. hespera ( Fig. 1 View Figure 1 ). Crematogaster browni and C. cerasi can be readily distinguished by differences in sculpture and pilosity. In workers of C. browni , the upper-third of the head is predominantly smooth and shiny, with relatively coarse punctures (greater than 0.01 mm in diameter), while in workers of C. cerasi , this region tends to have a greater incursion of reticulate sculpture and finer punctures (<0.01 mm in diameter). As Buren (1968) observed, the standing hairs on workers of C. browni are unusually long. Measurement of the postpetiolar seta affords a simple way to separate the two species: in C. browni the length of this seta is about two-thirds of the width of the postpetiole (0.59–0.75× postpetiole width) ( Fig. 10A View Figures 3–12 ), whereas in C. cerasi , the same hairs are about one-half the width (0.42–0.54× postpetiole width) ( Fig. 10B View Figures 3–12 ). A plot of postpetiole setal length against head width clearly distinguishes the two taxa ( Fig. 40 View Figures 40–47 ). In addition, the first gastric (fourth abdominal) tergite has greater amounts of standing pilosity in C. browni (A4SC 14–30) compared to C. cerasi (A4SC 4–14). Buren (1968) distinguished workers of C. browni from those of C. cerasi by their shorter, stouter and less divergent propodeal spines, and a narrow petiole that was said to be only slightly wider than the postpetiole. Metric measurements reveal average differences in these directions, but also indicate broad overlap in both propodeal spine length (SPL/HW 0.18–0.24 in C. browni and 0.22–0.25 in C. cerasi ) and the postpetiolar/petiolar width ratio ( PPW / PTW 0.83–0.96 in C. browni and 0.81–0.91 in C. cerasi ). Crematogaster browni can be distinguished from C. emeryana , the only closely related congener with an overlapping geographic range, by the coarser cephalic punctures, longer postpetiolar seta, greater contrast between abundant pilosity on the gaster and relatively sparse standing pilosity on the mesososma (A4SC >> MSC) and somewhat smaller eyes (worker ED/ MtFL 0.25–0.28, vs. 0.28–0.32 in C. emeryana ).

Distribution and biology: Crematogaster browni is found in mountainous regions of west Texas, New Mexico, Arizona and adjacent northern Mexico. Colonies are found in the ground, under stones, in high-elevation desert, oak savanna, juniper woodland and open oak-pine-juniper woodland. Buren (1968) provides additional details on habitat preferences and co-occurrence with other species of Crematogaster .