Crematogaster pilosa, Emery, 1895

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 : 922-923

CREMATOGASTER PILOSA EMERY, 1895

( FIG. 36 )

Crematogaster lineolata subsp. pilosa Emery, 1895: 285 . Syntype workers, District of Columbia and New Jersey (Pergande) (MHNG, NHMB). Syntype worker from New Jersey examined as image on AntWeb (CASENT0919707).

Status as species: Wheeler, 1919: 111; Creighton, 1950: 216; Buren, 1968: 92; Johnson, 1988: 321.

Crematogaster atkinsoni Wheeler, 1919: 108 . Six syntype workers, Fort Myers , Florida (J. W. Youngs) (LACM, MCZC) (examined). One worker in LACM (LACMENT182007) here designated as lectotype. Syn. nov.

Crematogaster atkinsoni var. helveola Wheeler, 1919: 109 . Three syntype workers, five males, one dealate queen, Okefenokee Swamp, Georgia (J. C. Bradley) (MCZC). One syntype worker (MCZENT00020823) here designated as lectotype. Syn. nov.

Crematogaster atkinsoni var. helveola as junior synonym of C. atkinsoni: Creighton, 1950: 207 .

Crematogaster atkinsoni as junior synonym of C. laeviuscula: Morgan & Mackay, 2017: 197 ; here overturned.

Crematogaster atkinsoni helveola (misspelled as ‘ haeveola ’) as junior synonym of C. laeviuscula: Morgan & Mackay, 2017: 197 ; here overturned.

Crematogaster (Acrocoelia) creightoni Wheeler, 1933: 86 . Syntype alate queens, Roanoke , Virginia, 10 September 1932 (W. S. Creighton) ( FMNH, MCZC, NHMB, USNM) . Syntype queens examined as images on AntWeb: FMNHINS0000062697, FMNHINS0000062698, CASENT0912712 and CASENT0105566. Synonymy by Buren in Smith, 1958: 127.

Worker measurements (N = 11). HW 0.85–1.04, HL 0.75–0.96, SL 0.69–0.84, WL 0.89–1.16, MtFL 0.71– 0.88, MSC 10–30, A4SC 20–60, PP-SL/HW 0.17–0.23, CI 1.05–1.17, OI 0.22–0.25, SI 0.78–0.83, MtFL/HW 0.82–0.88, SPL/HW 0.22–0.29, SPTD/HW 0.55–0.68.

Discussion: As the name implies, this species is characterized by its conspicuous standing pilosity. In particular, the pubescence on the head, mesosoma and gaster of the worker has a tendency to become uplifted (suberect or subdecumbent) and grade into the longer erect hairs, increasing the total amount of standing pilosity (MSC 10–30, A4SC 20–60). The length of the longest postpetiolar seta is half or more the width of the postpetiole (PP-SL/PPW 0.49–0.60). The propodeal spines are usually long (SPL/HW 0.22–0.29) and divergent (SPTD/HW 0.55–0.68). As noted by others ( Johnson 1988), this species is variable and specimens from the northern part of the range, including the C. pilosa syntypes, tend to be more pilose than those from farther south. Examination of type specimens and other material indicates that C. atkinsoni and C. atkinsoni helveola, described from Florida and Georgia, respectively, are junior synonyms of C. pilosa , not C. laeviuscula (cf. Morgan & Mackay, 2017). If the southern pilosa -like populations prove to be specifically distinct from the more setose northern populations of C. pilosa , then the name C. atkinsoni is available for them. For the moment we are treating them as conspecific. Phylogenomic data show that C. pilosa and C. laeviuscula are closely related – they are sister-species in our UCE tree ( Fig. 1 ). Some samples of putative C. laeviuscula from eastern Texas have workers that are atypically dark and hairy, suggesting the possibility of gene flow between these taxa.

Type notes: The syntype workers of C. atkinsoni are in poor condition: over-glued, greasy and abraded. The least degraded specimen is one of the LACM workers and it has been been selected as lectotype. It shows the uplifted pubescence on the head that characterizes C. pilosa , although it is on the less pilose end of the spectrum (MSC ~10, A4SC ~25) for this species. Creighton (1950) found that the type series of C. atkinsoni var. helveola was mixed, with the males, dealate queen and some workers being C. ashmeadi, while the remaining workers were a second species that Creighton (1950) considered to be C. atkinsoni . We examined three worker syntypes of Crematogaster atkinsoni helveola in the MCZC from Okefenokee Swamp. All of these have long propodeal spines and conspicuous standing pilosity that grades into subdecumbent pubescence, making them conspecific with C. atkinsoni and hence also C. pilosa . We have selected as lectotype the worker imaged on MCZbase (https://mczbase.mcz.harvard.edu/guid/ MCZ:Ent:20823). A label on this specimen indicates that it had been chosen as a lectotype of C. helveola by Buren in 1982, but this action was never published. The Okefenokee series also includes a small, headless dealate queen (WL ~2.10, MtFL 1.04) with short propodeal spines, and five small males (HW, including eyes, 0.67–0.73 mm); the queen and males appear to be C. ashmeadi (non-conspecific paralectotypes). Also labelled as ‘co-types’ of C. helveola are three workers, on a single pin, from Pinnacle, Georgia, collected by Bradley; two of these are C. ashmeadi and one is C. atkinsoni (= C. pilosa ). Because Okefenokee Swamp was explicitly cited as the type locality in the original description ( Wheeler, 1919: 110), we do not consider these Pinnacle specimens to be paralectotypes.

Distribution and biology: Crematogaster pilosa occurs along the east coast of the United States from New Jersey to Florida, west to at least Mississippi and Louisiana. The species is predominantly arboreal, nesting in logs, branches, dead stems and grass clumps, and it has been recorded from a variety of habitats, including marshes, coastal dunes, old fields and forested sites ( Johnson, 1988; Deyrup, 2017).

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 31–36. Crematogaster workers, showing lateral view of body (A), full-face view of head (B) and dorsal view of body (C). 31, C. cerasi lectotype (USNMENT00529078); 32, C. vermiculata (CASENT0914534); 33, C. rifelna holotype (LACMENT164556);34, C.ashmeadi (CASENT0922720); 35, C.pinicola (CASENT0172943); 36,C.pilosa(CASENT0914530). Images courtesy of AntWeb (www.antweb.org); photographers Michele Esposito (31, 33), Zach (Ziv) Lieberman (32, 36), Wade Lee (34), April Nobile (35).