Nylanderia magnella

Collections have been made at multiple sites in southern California coastal sagebrush and grassland habitats. Local vegetation includes Artemisia californica, Nassella pulchra, Brassica nigra, Salvia mellifera, other native and non-native grasses, and burned Ceanothus chaparral (C. Rochester, pers. comm.). Collections of this species made in this region were primarily by pitfall traps (Mitrovich et al., 2010). This species is also found in urban areas, including sidewalk cracks and near homes (M. Martinez, pers. comm.). Arizona material is known from a single locality collected in August with only reproductive castes present. Apparently nests are polydomous and likely polygynous (M. Martinez, pers. comm.) (Kallal & LaPolla, 2012).

Identification
Kallal & LaPolla (2012) - Overall orange-brown in color and relatively large (TL: 2.3–2.6); distinct square shaped head; scapes with a dense layer of pubescence.

Compare with: Nylanderia bruesii, Nylanderia terricola, and Nylanderia vividula.

Its slight orange-brown bicolored pattern and sparse pubescence may make it difficult to distinguish from N. terricola and N. vividula, but its relatively dense scape pubescence and very square head shape make it unique. The reproductive castes make this species easily distinguishable. Males and queens are both among the largest in the Nearctic, with only N. bruesii of comparable size. Although both N. magnella and N. bruesii males share a cylindrical, elongate gaster, their genitalic structures are very different, especially given that the digiti of N. magnella possess a very unique bifurcating tip that appears in no other Nearctic Nylanderia.

Identification Keys including this Taxon

 * Key to Nearctic Nylanderia workers

Distribution
Known from three regions in the desert southwest of the United States: central Arizona, southern Nevada, and southwestern California.

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

Nomenclature

 *  magnella. Nylanderia magnella Kallal & LaPolla, 2012: 25, figs. 31-33, 68, 125-132, 195 (w.q.m.) U.S.A.

Type Material


Kallal & LaPolla (2012) - A single worker has been collected from southern California (Santa Barbara Co., Sedgwick Ranch, 34°44’ N, 120°02’ W, elev. 610 m, 2.iii.1996), with a similarly square head. However, the head, mesosoma, and gaster are all more pubescent than what we have observed on other N. magnella specimens. This may indicate that this character is more variable within N. magnella than we currently recognize or that the specimen represents a new species. It is hoped that additional collecting from this area will clarify the identity of this specimen.

Worker
Measurements (n=14) TL: 2.25–2.63; HW: 0.52–0.62; HL: 0.67–0.73; EL: 0.14–0.18; SL: 0.76–0.88; PW: 0.37–0.45; WL: 0.79–0.92; GL: 0.70–1.09; PH: 0.21–0.29; PFL: 0.57–0.78; PFW: 0.14–0.20. SMC: 1–9; PMC: 2–7; MMC: 2–3. Indices: CI: 78–88; REL: 20–25; SI: 109–123; FI: 86–113.

Overall uniform orange-brown in color, sometimes with darker brown gaster; mesocoxae and metacoxae same color as mesosoma; cuticle smooth and shiny; cephalic pubescence sparse; mesosoma pubescence sparse; gastral pubescence sparse dorsally and virtually absent laterally and ventrally. Head distinctly quadrate; posterior margin very slightly emarginated medially; scapes surpass posterior margin by first 3 funicular segments; scapes with decumbent pubescence; ocelli not apparent. Pronotal anterior face approximately 45°; pronotum inflected with shorter anterior pronotal face and longer dorsal pronotal face; anterior margin of mesonotum slightly above pronotal margin; propodeum gently rounded with dorsal and declivitous faces of approximately equal length.

Queen
Measurements (n=4) TL: 4.39–4.73; HW: 0.80–0.83; HL: 0.80–0.82; EL: 0.24–0.29; SL: 0.82–0.95; PW: 0.85–0.92; MW: 0.81–0.85; WL: 1.32–1.78; GL: 2.12–2.36; PH: 0.32–0.46 ; PFL: 0.74–0.78; PFW: 0.17–0.24. SMC: 1–5; PMC: 4–9; MMC: 6–11; MtMC: 2–3. Indices: CI: 98–102; REL: 29–35; SI: 102–111; FI: 91–96.

Orange brown in color, with head and gaster slightly darker, legs and antennae slightly lighter; cuticle smooth and shiny; body with dense pubescence; macrosetae brown. Head as broad as it is long; scapes surpass posterior margin by first 3–4 funicular segments. Propodeum with very short dorsal face and long, sloping declivitous face.

Male
Measurements (n=6) TL: 2.99–3.50; HW: 0.61–0.71; HL: 0.63–0.73; EL: 0.26–0.28; SL: 0.83–0.88; PW: 0.67–0.73; MW: 0.62–0.68; WL: 1.07–1.21; GL: 1.19–1.58; PH: 0.29–0.40; PFL: 0.76–0.82; PFW: 0.17–0.22; PL: 0.21–0.30. SMC: 1–4; MMC: 8–13; MtMC: 2–5. Indices: CI: 84–111; REL: 35–45; SI: 116–136; FI: 106–122.

Orange-brown mesosoma and slightly more brown head and gaster; cuticle smooth and shiny; cephalic pubescence sparse to moderate; mesosoma pubescence densest on mesonotum; anepisternum, katepisternum and propodeum with patches of moderate pubescence; pronotum with scattered pubescence laterally. Head usually as broad as it is long; eyes weakly convex, scarcely extending beyond 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 long apical tooth and a single subapical. Mesosoma enlarged to accommodate flight muscles; in lateral view, pronotal margin short and relatively straight; propodeum with equally long dorsal and declivitous faces. Gaster long and cylindrical. Genitalia: parameres triangular, usually angled ventrally, appearing perpendicular to the body; cuspides short and rounded apically, meeting digiti at about their midlength; both structures with rounded teeth where they meet; digiti long, curved, and digitiform, with distinct bifurcated tips terminating in pointed digitiform structures; more ventrolaterally orientated digitiform structure about twice length of more dorsally oriented structure; aedeagal valve triangular proximally, digitiform distally, teeth absent; ninth sternite with short, broad ventral apodeme and long lateral apodemes.

Etymology
The species epithet magnella is a diminutive form of magna (L.= great), as the males in particular of this species are large, but only in comparison to the other relatively smaller sympatric species.