Nylanderia bruesii

This species is frequently found nesting under stones or otherwise shady areas near water, even in arid environments. Reproductives fly, as in the other Nearctic species, at the onset of warm, humid days (Trager, 1984).

Identification
Kallal & LaPolla (2012) - Large species (TL: 2.3–3.3); pronotum with dense pubescence; pronotum and mesonotum often lighter in color than mesopleuron and propodeum; mesosoma notum and gaster with densely distributed macrosetae.

Compare with: Nylanderia austroccidua.

In the United States, there can be little confusion in identifying N. bruesii with any other species except perhaps Nylanderia austroccidua. However, N. bruesii lacks the bluish coloration and angular pronotum of the latter, and is frequently more pubescent.

Distribution
The known range of N. bruesii extends from the desert southwest United States to Baja California Sur, Coahuila, and Sonora in Mexico (Kallal & LaPolla 2012).

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.

Habitat
Desert washes, mountainous hillsides, grassy meadows, and mesic forests populated by willow, cottonwood, oak, and juniper (Kallal & LaPolla, 2012).

Nomenclature

 *  bruesii. Prenolepis bruesii Wheeler, W.M. 1903b: 106, fig. 9 (w.q.m.) U.S.A. Wheeler, G.C. & Wheeler, J. 1968: 211 (l.). Combination in Pr. (Nylanderia): Emery, 1914f: 422; in Paratrechina (Nylanderia): Emery, 1925b: 222; in Nylanderia: LaPolla, Brady & Shattuck, 2010a: 127. See also: Trager, 1984b: 129; Kallal & LaPolla, 2012: 15.

Worker
Kallal & LaPolla (2012) - Measurements (n=15) TL: 2.37–3.23; HW: 0.59–0.72; HL: 0.65–0.85; EL: 0.16–0.21; SL: 0.73–0.95; PW: 0.39–0.55; WL: 0.78–1.01; GL: 0.86–1.46; PH: 0.22–0.28; PFL: 0.58–0.78; PFW: 0.15–0.22. SMC: 10–22; PMC: 3–10; MMC: 3–6. Indices: CI: 83–89; REL: 22–28; SI: 111–126; FI: 90–121.

Overall dark brown with mandibles, scapes, and legs lighter brown; pronotum and mesonotum sometimes lighter than mesopleuron and propodeum; mesocoxae and metacoxae sometimes lighter; cuticle smooth and shiny; cephalic pubescence moderate to dense; pronotum with dense pubescence becoming less dense on mesonotum, anteriodorsal area of propodeum with a narrow band of moderate pubescence; gastral pubescence moderate, densest along segmental margins. Head ovate; posterior margin slightly emarginated medially; scapes surpass posterior margin by length of first 3–4 funicular segments; ocelli apparent. Pronotal anterior face at approximately 45°, without distinct inflection between pronotal anterior and dorsal faces; anterior margin of mesonotum continuous with posterior pronotal margin; propodeum rounded with slightly longer declivitous face.

Queen
Kallal & LaPolla (2012) - Measurements (n=2) TL: 4.58–5.13; HW: 0.94–0.98; HL: 0.97–1.10; EL: 0.26–0.29; SL: 1.03–1.04; PW: 0.95–1.1; MW: 0.89–0.99; WL: 1.64–1.7; GL: 1.97–2.39; PH: 0.56–0.57; PFL: 0.85–0.93; PFW: 0.22–0.24. SMC: 12–15; PMC: 6–10; MMC: 1–4; MtMC: 2. Indices: CI: 94–97; REL: 27–28; SI: 99–107; FI: 82–96.

Overall dark brown in color, with darker gaster darker, scapes, mandibles, and legs lighter; cuticle smooth and shiny; body with dense pubescence; macrosetae brown. Head broad as it is long; scapes surpass posterior margin by the length of 3–4 funicular segments. Propodeum with short dorsal face and long declivitous face.

Male
Kallal & LaPolla (2012) - MALE. Measurements (n=8) TL: 2.86–3.51; HW: 0.58–0.66; HL: 0.62–0.68; EL: 0.22–0.27; SL: 0.79–0.92; PW: 0.55–0.70; MW: 0.50–0.61; WL: 0.90–1.23; GL: 1.27–1.61; PH: 0.27–0.40; PFL: 0.71–0.89; PFW: 0.14–0.19; PL: 0.21–0.37. SMC: 5–12; MMC: 5–12; MtMC: 2–4. Indices: CI: 98–106; REL: 31–41; SI: 124–134; FI: 115–132.

Overall dark brown with lighter mandibles, scapes, and leg joints; cuticle smooth and shiny; cephalic pubescence dense; mesosoma with pubescence densest on mesonotum, extending to posterior pronotum, katepisternum, mesopleuron and propodeum; gastral pubescence moderate. Head as broad as long; eyes convex, extending beyond the lateral margins of the head in full face view; scapes surpass posterior margin by first 3–4 funicular segments; inner mandibular margin long and straight; basal angle approximately 90°; masticatory margin with large apical tooth plus two smaller subapical teeth. Mesosoma enlarged to accommodate flight muscles; in lateral view, pronotal margin gently curved; propodeum relatively flat, with dorsal face longer than declivitous face; gaster distinctly long and cylindrical. Genitalia: parameres long, distinctly narrow, digitiform; digiti gently curved ventrally, broadly flattened distally; digiti and cuspides meet about midlength of digiti with rounded teeth on both lobes; aedeagal valves with nearly parallel margins for much of length, becoming triangular in shape, teeth absent; ninth sternite almost square in shape with short, thin lateral apodemes and a long, slender ventral apodeme.

Additional References

 * Kallal, R.J. & LaPolla, J.S. 2012. Monograph of Nylanderia (Hymenoptera: Formicidae) of the World, Part II: Nylanderia in the Nearctic. Zootaxa 3508, 1-64.