Crematogaster, Ward, Philip S. & Blaimer, Bonnie B., 2022

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 : 927-928

CREMATOGASTER VETUSTA SP. NOV.

( FIG. 14 )

Zoobank registration: urn:lsid:zoobank.org:act:E2ACD687-1F5C-4EAA-BB19-A75C215C3670 . Type material: Holotype worker, US, Arizona, Cochise Co.: 11 km NNW Portal, 1430 m, 32.00293 −109.18198 ± 3 m, 8 Aug 2011, P. S. Ward PSW16646, ground forager, Chihuahuan desert (CASENT0863254) ( USNM).

P a r a t y p e s: F i v e w o r k e r s, s a m e d a t a a s holotype (CASENT0221037, CASENT0863251, C A S E N T 0 8 6 3 2 5 2, C A S E N T 0 8 6 3 2 5 3 CASENT0863255) (CASC, MCZC, UCDC).

Non-type material: MX, Sonora, 36.6 km SE El Golfo de Santa Clara , 15 m, 31°31.6 ′ N 114°9.8 ′ W, 27 Feb 2017, T. Van Devender, two workers (CASENT0882151) ( UCDC); ten workers, same data but without specimen codes (RAJC) ; US, Arizona, Pima Co.: Brown Cañon, Baboquivari Mtns., 5000 ft., 17 Sept. 1951, W. S. Creighton, three workers (LACMENT 403634) ( LACM); Cochise Co. : Chiricahua Mtns., Cave Creek Canyon , Sunny Flat Campground , 4950 ft., 2-VII-1986, S. P. Cover #862, 18 workers (MCZENT00588704, MCZENT 00589124, MCZENT 00589125, MCZENT 00589126, MCZENT 00589127, MCZENT 00589128, MCZENT 00589129, MCZENT00589130, and CASENT0173014 with redundant specimen code MCZENT00589131) (MCZC); Cochise Co. : Chiricahua Mtns., SWRS, 8 km W Portal, 1650 m, 31°53 ′ N 109°12 ′ W, 4–14.viii.2005, Ant Course, two workers (MCZENT00589132) (MCZC) .

Worker measurements (N = 11): HW 0.96–1.27, HL 0.89–1.17, SL 0.80–1.02, WL 1.04–1.40, MtFL 0.86– 1.16, MSC 6–24, A4SC 38–70, PP-SL/HW 0.10–0.13, CI 1.06–1.12, OI 0.24–0.25, SI 0.74–0.83, MtFL/HW 0.87–0.94, SPL/HW 0.20–0.23, SPTD/HW 0.46–0.55.

Worker diagnosis: Head broader than long, with convex sides, and weakly concave posterior margin (more strongly so in larger workers); scapes moderately long, surpassing the posterior margin of head by distal scape width or more (SI 0.74–0.83, SL/HL 0.82–0.92, SL/WL 0.68–0.79); eye of moderate size (OI 0.24–0.25, ED/ HL 0.26–0.28, ED/MtFL 0.27–0.29); promesonotum lacking well-marked pronotal humeri and mesonotal declivity; propodeal spines relatively long (SPL/HW 0.20–0.23, SPL/WL 0.18–0.21) and divergent (SPTD/ HW 0.46–0.55); petiole subtrapezoidal, narrow (PTW/ HW 0.32–0.35); postpetiole relatively narrow (PPW/ HW 0.27–0.30), the hemilobes not strongly angulate in profile; legs relatively long (MtFL/HW 0.87–0.94, MtFL/HL 0.96–1.02). Mandibles striate; head reticulate to reticulate-striolate, with shiny median patch (more extensively smooth and shiny in smallest workers); mesosoma predominantly reticulate-foveolate and opaque, with overlying irregular rugulae on the promesonotum, and better developed longitudinal rugulae on the dorsal face of the propodeum; declivitous face of propodeum weakly reticulate to smooth and shiny; petiole and postpetiole reticulate to reticulate-foveolate, subopaque. Head, including scapes, and mesosoma with short but conspicuous standing pilosity, grading into (and sometimes difficult to distingush from) decumbent pubescence (MSC 6–24); postpetiolar seta short (PP-SL/ HW 0.10–0.13), and flanked by several adjacent setae of almost equal length; short standing pilosity especially common on gaster (A4SC 38–70). Dark reddish-brown, gaster and appendages lighter.

Comments: The key distinguishing features of the worker of C. vetusta are the dense reticulatefoveoleate sculpture of the mesosoma, overlain by weak rugulae; short standing pilosity of the head and mesosoma which grades into uplifted pubescence (MSC 6–24); abundant, short, standing pilosity on the gaster (A4SC 38–70); relatively long and divergent propodeal spines (SPL/HW 0.20–0.23); and narrow petiole (PTW/HW 0.32–0.35) and postpetiole (PPW/HW 0.27–0.30). Other species from the southwestern United States with similarly abundant pilosity on the gaster (A4SC> 35 in at least some workers) differ as follows: C. dentinodis is darker, with smaller eyes (ED/HL 0.24–0.26) and a broader petiole (PTW/HW 0.37–0.41) and postpetiole (PPW/ HW 0.32–0.35); C. punctulata is smaller and darker, with more conspicuous mesosomal pilosity (MSC 16–28), shorter legs (MtFL/HL 0.82–0.96) and less divergent propodeal spines (SPTD/HW 0.39–0.46); C. navajoa has a much shinier integument, much longer standing pilosity (PP-SL/HW 0.17–0.25), more abundant pilosity on the mesosoma (MSC 18–29) and a broader postpetiole (PPW/HW 0.29–0.35); and C. marioni has a shinier integument, shorter scapes and legs (SL/HL 0.73–0.81, MtFL/HL 0.83–0.90) and generally less standing pilosity on the gaster (A4SC 19–38). All of the above species, except C. navajoa, also have more appressed pubescence on the scapes than C. vetusta, although this character shows considerable variation among and within species. The UCE phylogenetic tree ( Fig. 1 ) reveals that C. vetusta is a member of the C. opaca clade and sister to C. detecta . The latter species is easily distinguished from C. vetusta by its scarcity of standing pilosity (MSC 0, A4SC 0–3).

Biology and distribution: This species is known only from southern Arizona and northern Sonora. The type series (PSW16646) consists of daytime foragers collected in the Chihuahuan desert, on a rocky quartzite hill with Vachellia, Fouquieria, Yucca, Agave and scattered Juniperus and Sapindus saponaria L.. Stefan Cover’s collection #862 was taken under a rock in an open gap, in creek floodplain forest with Quercus grisea Liebm., Q. emoryi Torr. and Platanus occidentalis L. The collection from Sonora, Mexico was taken from sand dunes in Sonoran desert-scrub .

Etymology: The name refers to the position of this species in a lineage (containing one other known species) that is sister to all other members of the C. depilis complex, from Latin vetustus, old or antiquated.

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).

Figures13–18. Crematogaster workers,showing lateral viewof body (A),full-faceview of head(B) and dorsalview ofbody (C). 13, C. dentinodis (CASENT0102830); 14. C. vetusta holotype (CASENT0863254); 15, C. navajoa worker (CASENT0064826); 16, C. punctulata lectotype (CASENT0923318); 17, C. isolata (CASENT0922731); 18, C. sp. cf. opaca (MCZENT00589113). Images courtesy of AntWeb (www.antweb.org); photographers Jen Fogarty (13), Michele Esposito (14, 16), April Nobile (15), Wade Lee (17), Zachary Griebenow (18).