Crematogaster opuntiae, BUREN, 1968

Ward, Philip S. & Blaimer, Bonnie B., 2022, Taxonomy in the phylogenomic era: species boundaries and phylogenetic relationships among North American ants of the Crematogaster scutellaris group (Formicidae: Hymenoptera), Zoological Journal of the Linnean Society 194, pp. 893-937 : 919

CREMATOGASTER OPUNTIAE BUREN, 1968 , STAT. REV.

( FIG. 25 )

Crematogaster opuntiae Buren, 1968: 120 . Holotype worker, Santa Rita Experimental Range , Arizona (Buren) (LACM) (examined).

Junior synonym of C. vermiculata: Morgan & Mackay, 2017: 396 ; here overturned.

Worker measurements (N = 10): HW 0.86–1.21, HL 0.80–1.11, SL 0.72–0.94, WL 0.89–1.27, MtFL 0.74– 1.05, MSC 1–3, A4SC 5–16, PP-SL/HW 0.14–0.19, CI 1.05–1.11, OI 0.26–0.29, SI 0.75–0.84, MtFL/HW 0.85– 0.89, SPL/HW 0.19–0.25, SPTD/HW 0.50–0.59.

Discussion: Crematogaster opuntiae bears little similarity or close phylogenetic relationship ( Fig. 1 ) to the eastern, swamp-inhabiting species C. vermiculata , under which it was synonymized by Morgan & Mackay (2017). Among obvious differences, it has longer scapes and legs (SL/HL 0.83–0.90 and MtFL/HL 0.91–0.95 compared to SL/HL 0.75–0.82 and MtFL/HL 0.84–0.89 in C. vermiculata ), predominantly reticulate-foveolate sculpture on the promesonotum, more divergent propodeal spines (SPTD/ PPW 1.71–1.96 compared to 1.15–1.48 in C. vermiculata ) and lesser amounts of standing pilosity (MSC 1–3 and A4SC 5–16, compared to MSC 3–9 and A4SC 9–20 in C. vermiculata ). As noted by Buren (1968), C. opuntiae is similar to C. californica , differing primarily by the shinier head and by the more appressed pubescence on the scapes and head. The relationship of C. opuntiae to C. californica remains to be clarified – they may well prove to be conspecific. Crematogaster opuntiae has similar eye, scape, leg ( Fig. 42 ) and propodeal spine dimensions as C. californica , and in our phylogenomic analyses the two are sister-taxa ( Fig. 1 ).

Distribution and biology: Buren (1968) recorded C. opuntiae from desert and semi-desert regions of Arizona and considered C. californica to be restricted to California and Baja California. Both taxa are ground-nesting.

Figures

Figure 1. Phylogeny of the North American Crematogaster scutellaris group. Maximum likelihood phylogenetic tree estimated from the 90% taxon completeness matrix after application of spruceup trimming with a 0.98 cut-off (90%-0.98-spruceup), using a combined best tree and ultrafast bootstrap (N = 1000) search in IQ-TREE v.1.6.12 and implementing 746 partitions. The analysis was rooted using the most distantly related outgroup taxon C. cf.rogenhoferi; the long branch leading to this taxon has been shortened for space-saving purposes. All nodes have bootstrap support = 100% unless labelled otherwise. Species images courtesy of AntWeb (www.antweb.org).

Figures 25–30. Crematogaster workers, showing lateral view of body (A), full-face view of head (B) and dorsal view of body (C). 25, C. opuntiae (CASENT0922738); 26, C. marioni (CASENT0922734); 27, C. coarctata (CASENT0005667); 28, C. hespera holotype (USNMENT00529501); 29, C. browni (CASENT0922722); 30, C. emeryana (CASENT0922729). Images courtesy of AntWeb (www.antweb.org); photographers Wade Lee (25, 26, 29, 30), April Nobile (27), Michele Esposito (28).

Figures 40–47. Bivariate plots of selected worker measurements in the Crematogaster scutellaris group. 40, PP-SL (postpetiole seta length) by HW (head width) in C. browni (N = 16) and C. cerasi (N = 17); 41, ED (eye diameter) by MtFL (metafemur length) in C. californica (N = 22) and C. coarctata (N = 21); 42, MtFL (metafemur length) by HW (head width) in C. californica (N = 22), C. colei (N = 12) and C. opuntiae (N = 10); 43, MtFL (metafemur length) by HW (head width) in C. depilis (N = 15), C. detecta (N = 11) and C. larreae (N = 5); 44, MtTL (metatibia length) by HW (head width) in C. depilis (N = 15), C. detecta (N = 11) and C. larreae (N = 5); 45, SPL (propodeal spine length) by HW (head width) in workers of C. hespera (N = 18), C. laeviuscula (N = 25) and C. parapilosa (N = 15); 46, SL (scape length) by HW (head width) in C. emeryana (N = 12) and C. marioni (N = 18); 47, SPTD (propodeal spine tip distance) by HW (head width) in C. lineolata (N = 26) and C. punctulata (N = 15).