Novomessor albisetosus

(Mayr, 1886)

desert harvester ant

Novomessor albisetosus, commonly known as the desert harvester ant, is a medium-sized native to the southwestern United States and northern Mexico. First described by Gustav Mayr in 1886 as Aphaenogaster albisetosa, it was transferred to the revived Novomessor in 2015 following phylogenetic evidence of its distinctness from Aphaenogaster. measure 6–8.5 mm and display ferruginous body coloration with distinctive morphological features including a shorter and subparallel compared to . The species exhibits age-related task allocation among workers and cooperative foraging , with colonies nesting underground or beneath stones in arid and semi-arid .

Novomessor albisetosus by (c) Jake Nitta, some rights reserved (CC BY), uploaded by Jake Nitta. Used under a CC-BY license.

Pronunciation

How to pronounce Novomessor albisetosus: //noʊ.voʊˈmɛs.ɔr æl.bɪˈsɛ.tə.səs//

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Identification

Distinguished from Novomessor cockerelli by shorter (queens: head slightly longer than broad versus decidedly longer than broad in N. cockerelli); subparallel position versus more elongated head shape in N. cockerelli; spines more bent and curved downward versus bent inward in N. cockerelli; epinotal spines as long as basal of epinotum versus shorter spines in N. cockerelli; heavier body sculpturing with greater opacity and nearly opaque petiole versus shinier epinotum and head in N. cockerelli; hairier with coarse whitish-yellow hairs. shorter and higher than in N. cockerelli. Nests with smaller gravel discs than N. cockerelli, sometimes absent when nest under stones. From N. ensifer by larval characteristics: N. albisetosus larvae with sparse, short body hairs versus abundant long stout hairs in N. ensifer.

Images

Appearance

Medium-sized measuring 6–8.5 mm in length with a moderately short, stout body. Body color ferruginous (rust-colored); legs reddish brown; petiole and brownish black, with first abdominal segment brownish yellow. noticeably long, longer than wide, with subparallel sides to and convex sides to eyes. longer than wide, positioned medially with two vertical stripes. Eyes subparallel. with three comparatively large teeth; form triangular isosceles shape. Tibiae bear fine, clear bristles. Body covered with coarse whitish-yellow hairs that taper from base to blunt tip; abdomen with numerous hairs shorter than those on pronotum. Petiole nearly opaque with heavier sculpturing. Spines more bent and curved downward compared to N. cockerelli. Queens with head slightly longer than broad; shorter and higher than in N. cockerelli.

Habitat

Desert , juniper woodland, pine-oak woodland, and riparian woodland/desert scrub. Nests constructed underground or beneath stones at elevations of 654–1,780 m (2,146–5,840 ft). Nest entrances irregular, roughly 7.6–10.2 cm (3–4 in) across, descending steeply; entrance surrounded by disc of coarse gravel and excavated soil, smaller than those of N. cockerelli and sometimes absent in stone-nesting colonies. Northern distribution limited by inability to survive in highland areas.

Distribution

Southwestern United States (Texas, New Mexico, Arizona) and northern Mexico (Chihuahua, Durango, Sonora). Easternmost record near Cernas Ranch in Chisos Mountains, Texas; likely occurs in adjacent northern Coahuila, Mexico. Range extends south along eastern Sierra Madre Occidental to northwestern Chihuahua, then west to Sonoran coastal plain. Less widespread than N. cockerelli; does not extend as far north and occurs much further south. Absent from Mogollon Mesa and highland areas of central Arizona and New Mexico.

Seasonality

begin in June. active during morning and evening hours, avoiding midday heat and middle of night; foraging activity occurs when air temperatures between 20–40°C (68–104°F).

Diet

Insect pieces, seeds, plant tissues, and fruit pieces. Seeds not strongly preferred; insect pieces comprise approximately 6% of collected items, likely scavenged from already deceased insects rather than actively preyed upon due to slow locomotion.

Life Cycle

Complete with , larva, pupa, and stages. Larvae measure 6.6 mm, moderately stout with slight constriction at first and second abdominal somites; small, without spinules, body hairs short and sparse. begin June. exhibit age : young workers perform intranidal tasks ( and care), transitioning to extranidal activities (foraging) with age; maturity defined as spending more than half of time outside nest. Mature workers can revert to intranidal tasks when colony age structure disrupted. Ovarian development in queens correlates with presence of workers; ovarian resorption occurs when worker care ceases.

Behavior

Foraging primarily individual but recruits nestmates cooperatively for large food items. stridulate when encountering food too large to carry alone; vibrations perceived only by nearby workers or those in direct contact. Trail-following: can follow trails of N. cockerelli, but N. cockerelli cannot follow N. albisetosus trails. Aggressive toward intruders, especially non-resident conspecifics and N. cockerelli; eliminated Pogonomyrmex badius when introduced to nest area. Activity pattern , avoiding extreme temperatures; water availability limits foraging duration, with extended foraging periods when seed supplements provided.

Ecological Role

Prey for army ants (Neivamyrmex). Seed through foraging activities, though seeds not preferred food item.

Similar Taxa

Novomessor cockerelliOverlapping range and ; distinguished by longer , shinier sculpturing, shorter epinotal spines, and inability to follow N. albisetosus trails. Constructs larger nest entrance discs.
Novomessor ensiferLarval similar; distinguished by larval hair abundance and length.
Aphaenogaster speciesFormerly classified in same ; distinguished by absence of exocrine gastral glandular system and different promesonotal and postpetiole structure.