Crematogaster

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 : 914

CREMATOGASTER DEPILIS WHEELER, 1919

( FIGS 4B , 23 )

Crematogaster lineolata opaca var. depilis Wheeler, 1908: 478 (unavailable name).

Crematogaster opaca var. depilis Wheeler, W.M. 1919: 111 (first available use of name). Lectotype worker, Cerro Carrizal , Chihuahua, Mexico (Townsend) (MCZC) (MCZENT00303629) (examined).

Crematogaster (Acrocoelia) lineolata subsp. opaca var. depilis Wheeler ; Emery, 1922: 141.

Crematogaster (Acrocoelia) punctulata var. depilis Wheeler ; Enzmann, 1946: 93.

Crematogaster (Acrocoelia) depilis Wheeler ; Creighton, 1950: 209.

Crematogaster (Crematogaster) depilis Wheeler ; Buren, 1968: 93.

Senior synonym of C. larreae Buren : Morgan & Mackay, 2017: 155; here overturned (see below).

Worker measurements (N = 15): HW 0.85–1.18, HL 0.79–1.12, SL 0.69–0.89, WL 0.88–1.27, MtFL 0.74–1, MSC 0, A4SC 0–3, PP-SL/HW 0.07–0.12, CI 1.02–1.15, OI 0.27–0.30, SI 0.72–0.81, MtFL/HW 0.80–0.87, SPL/ HW 0.16–0.24, SPTD/HW 0.42–0.56.

Discussion: Our phylogenomic results indicate that C. depilis is sister to ( C. larreae + C. mutans) ( Fig. 1 ), but further study of this complex is needed. Workers of C. depilis can be characterized as follows: mesosoma, petiole and postpetiole densely reticulate-foveolate and opaque, with overlying irregular rugulae on the promesonotum and dorsal face of propodeum; standing pilosity sparse: absent from mesosoma dorsum and usually lacking on fourth abdominal tergite (if present on the latter then restricted to 1–3 short hairs on the posterior margin); legs relatively short and eye relatively large (MtFL/HW 0.80–0.87, ED/MtFL 0.32– 0.37); head and mesosoma light yellowish- to reddishbrown (head may be darker than mesosoma), gaster medium to dark brown.

Type notes: From a series of 11 syntype workers in the MCZC, attached to two cards on a single pin, Morgan & Mackay (2017: 160) chose a lectotype worker, identifying it as ‘worker on far right of top card designated by red dot and labeled as lectotype’. Upon examining this pin, we found that no lectotype label had been affixed to it, but there is a red dot on the card, so we have printed and attached a label that confirms the lectotype designation. Despite their labelling oversight, Morgan & Mackay’s (2017) published statement would appear to meet the requirements for lectotype designation, under Article 74.7.3. of the International Code of Zoological Nomenclature. The lectotype worker and ten paralectotype workers are part of a nest series collected by Townsend in beetlebored branches of mesquite in which the ants were observed tending coccids ( Wheeler, 1908: 479).

Distribution and biology: Material corresponding to the above description comes from a wide variety of arid locations, from Texas to California and south to northern Mexico. Nevertheless, there is some uncertainty about whether all such populations are conspecific, and there are closely similar taxa that are difficult to distinguish from C. depilis (see C. detecta and C. larreae , below). Most collections are from desert habitats, with foragers frequently collected on cacti, and colonies located under stones, directly in the soil and in buried wood and roots.

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 3–12. Crematogaster worker features useful for identification. 3, petiole shape, dorsal view, C. lineolata (CASENT0863235) (3A) and C. torosa (CASENT0795540) (3B); 4, sculpture on declivitous face of propodeum, C. dentinodis (CASENT0863070) (4A) and C. depilis (CASENT0863478) (4B); 5, mesosomal pilosity, C. punctulata (CASENT0863277) (5A) and C.emeryana (CASENT0863099) (5B); 6, position and shape of propodeal spines, dorsal view, C.isolata (CASENT0863072) (6A) and C.pinicola (CASENT0882129) (6B); 7, petiole shape, dorsal view, C.mutans (CASENT0862488); 8, subpetiolar tooth, lateral view, C.mutans (CASENT0862488); 9, promesonotal sculpture, C.californica (CASENT0221085)(9A) and C.coarctata (CASENT0221962) (9B); 10, postpetiolar seta, C. browni (CASENT0863144) (10A) and C. cerasi (CASENT0795541) (10B); 11, cephalic pilosity, C. torosa (CASENT0795540) (11A) and C. missouriensis (CASENT0221041) (11B); 12, mesosomal profile, C. crinosa (CASENT0795543) (12A) and C. torosa (CASENT0863226) (12B).

Figures 19–24. Crematogaster workers, showing lateral view of body (A), full-face view of head (B) and dorsal view of body (C). 19, C. mutans worker (CASENT0922736); 20, C. colei (CASENT0922726); 21, C. detecta holotype (CASENT0863461); 22, C. larreae paratype (CASENT0005943); 23, C. depilis (CASENT0005668); 24, C. californica lectotype (CASENT0923319). Images courtesy of AntWeb (www.antweb.org); photographers Wade Lee (19, 20), Zachary Griebenow (21), April Nobile (22, 23), Michele Esposito (24).