Nylanderia vividula

Nests are found in a wide variety of habitats across the Nearctic, ranging from under stones in forests to urban environments. Substrates can include everything from fine sandy clay to damp potting soil. The adaptive nature of this species translates into its distribution across much of the Nearctic region of the United States and Mexico. Reproductives may fly year round, given it is sufficiently warm and humid, and males are usually present in the nest (Trager, 1984) (Kallal & LaPolla, 2012).

Identification
Kallal & LaPolla (2012) - Usually brown and bicolored with head and gaster darker than mesosoma, and lighter mesosoma and legs; sparse pubescence on head; head square in shape.

Compare with: Nylanderia austroccidua, Nylanderia concinna, Nylanderia flavipes, and Nylanderia terricola.

Nylanderia vividula is one of the few species that is found in both the eastern and western United States and Mexico. The species varies in overall coloration from brownish yellow to dark brown, and its mesocoxae and metacoxae color range from being the same color as the mesosoma to being pale and contrasting with its body. This makes the species easily confused with multiple other species with which it occurs sympatrically. In particular, the workers of N. vividula and N. terricola are nearly indistinguishable from each other. The only possible way to morphologically distinguish them is by head shape and relative eye size, but even these features are not always reliable. N. vividula has a squarer head with close to parallel lateral margins in full face view while N. terricola has more convex lateral margins, resulting in a slightly oval appearance. Regarding eye size, the length of the eye relative to the head length (ocular index) in N. vividula is usually more than that of N. terricola, with the latter infrequently exceeding 24 (Trager, 1984). But in both of these morphological features there is broad overlap.

In California, N. terricola is paler than N. vividula, and is often found in natural, arid habitations rather than disturbed ones (P. Ward, pers. comm.). Additionally, an index of eye length divided by scape length is often lower in N. terricola versus N. vividula. It should be noted that while these are useful in California, they do not seem to apply elsewhere where the two species’ ranges overlap.

Ultimately, males are best used to separate the species. N. vividula parameres curve inward, especially evident when viewed dorsally, and lack distally digitiform structure found in N. terricola. Additionally, the digiti and aedeagal valves do not taper then expand into broad tips, as they do in N. terricola. The ninth sternites are also very different. In N. vividula, it is triangular, growing wider proximally, whereas the ninth sternite is short and broad in N. terricola.

In the eastern United States, N. vividula may be confused with N. concinna and N. flavipes. However, both of these have dense head pubescence, which N. vividula lacks. N. concinna is not bicolored and has brown, rather than yellowish, scapes. N. flavipes is bicolored, but the presence of apparent ocelli usually indicates it is not N. vividula. In the western U.S. and Mexico, N. austroccidua may be bicolored with lighter legs and scapes, but its dense head pubescence, bluish reflections under microscopic examination, and angular pronotum are not found in N. vividula.

Distribution
Known from North America, Central America, Europe and Africa.

It is notable that this is probably the only native Nearctic species to be found outside the Nearctic region. Its type locality is in Europe, and collections have been cited in both Africa and the Neotropics (Kallal & LaPolla, 2012).

This taxon was described from Finland. It is also found in United Kingdom of Great Britain and Northern Ireland.

Biology
Hab. in caldariis temperaturae circ. + 25 C. horti botanici Helsingforsicnsis frequenter, Coccos plantarum avide investigans; agilissime cursitans, pavida. Nidificat in rimis caementi parietum et pavimentorum. Coit auctumno a fine m. Augusti ad Octobr. et Novembr.; inveniuntur tamen saltem mares usque ad initium anni sequeutis parcius. Paria copula juncta in parietibus caldariorum currentia vidi. E Rossia verisimiliter cum plautis hibernaculariis advecta est haec species, mitioris coeli primitus incola. A temperatura parum frigida cito soporatur. (Nylander 1846)

Nomenclature

 *  vividula. Formica vividula Nylander, 1846a: 900, pl. 18, figs. 2, 10-14 (w.q.m.) FINLAND. Combination in Prenolepis: Mayr, 1861: 52; in Pr. (Nylanderia): Emery, 1906b: 134; in Paratrechina (Nylanderia): Emery, 1925b: 223; in Nylanderia: Kempf, 1972a: 168; in Paratrechina: Trager, 1984b: 131; in Nylanderia: LaPolla, Brady & Shattuck, 2010a: 127. Senior synonym of picea: Mayr, 1876: 78; Mayr, 1886d: 431; of kincaidi Trager, 1984b: 75; of mjobergi: Kallal & LaPolla, 2012: 38. Current subspecies: nominal plus australis. See also: Emery, 1910a: 131; Radchenko, 2007: 33.
 * picea. Formica picea Buckley, 1866: 163 (w.) U.S.A. Junior synonym of vividula: Mayr, 1876: 78; Mayr, 1886d: 431. See also: Smith, D.R. 1979: 1444.
 * kincaidi. Prenolepis kincaidi Wheeler, W.M. 1906e: 350, fig. 1 (w.q.m.) BERMUDA. Combination in Paratrechina (Nylanderia): Emery, 1925b: 222; in Nylanderia: Kempf, 1972a: 167. Junior synonym of vividula: Trager, 1984b: 75.
 * mjobergi. Prenolepis (Nylanderia) vividula var. mjobergi Forel, 1908b: 64 (w.) SWEDEN. Combination in Paratrechina (Nylanderia): Emery, 1925b: 223; in Nylanderia: LaPolla, Brady & Shattuck, 2010a: 127. Junior synonym of vividula: Kallal & LaPolla, 2012: 38.

Type Material


Kallal & LaPolla (2012) - Syntypes of N. vividula antillana were examined (4 specimens from and found to match the syntype material available for N. guatemalensis, hence our decision to consider it a synonym of the latter species (see synoptic list of species). Syntypes of N. vividula australis Santschi (1929) examined (6 specimens from ) revealed a species that is certainly not N. vividula, but its status is difficult to assess until completion of on-going revisionary work of the Neotropical Nylanderia fauna.

Worker
Long. ¾ - 1 lin. nitida, ore cum mandibulis, capite infra, thorace subtus et pedibus sordide testaceis; capite supra lateribusque et abdomine fuscis; thorace quoque supra fusco, sed dilutiori h. e. colore testaceo magis interlucente. Setae fuscae sat validae in capite, pro- et mesonoto (pulvinar eommune efficientibus) atque in abdomine conspersae, in abdomine tamen crebriores quam in cetero corpore. Autennae graciles long. fere ¾ lin. Laminal frontalis inter antennas vestigia solum obsoleta, marginibus scilicet nullis, fronteque aequaliter convexiuscula inter radice antennarum pauxillum tentum tumidiuscula. Ocelli nulli. Abdomen setosum magnitudinem capitis vix superans, ovatum.

Kallal & LaPolla (2012) - Measurements (n=25) TL: 1.92–2.82; HW: 0.47–0.65; HL: 0.56–0.66; EL: 0.13–0.19; SL: 0.62–0.74; PW: 0.34–0.50; WL: 0.63–0.98; GL: 0.71–1.18; PH: 0.16–0.29; PFL: 0.49–0.74; PFW: 0.14–0.19. SMC: 4–14; PMC: 2–8; MMC: 1–4. Indices: CI: 79–93; REL: 21–30; SI: 92–122; FI: 86–110.

Overall the worker description for N. vividula matches the description of Nylanderia terricola. The difference between workers of these two species is slight and not always morphologically consistent. The main difference is that N. vividula possesses a head with lateral margins that are subparellel, giving the head a slightly squarer appearance in comparison to N. terricola.

Queen
Long. 1 1/2 lin. cinereo-micans, abdomine fusco, capite supra parum fuscescente, cetero corpore sordide testaceo. Caput fere ut in regina, scil. a latere visum ovalum; oculi parum prominuli, clypeus nitidus tumidulus in medio longitrorsum elevatus; sed differt lamina frontali parum distinctiori, antennis paulo validioribus licet ejusdem longitudinis, ocellis et canitie levi, certo situ micante. Scutellum deplanatum semicirculare. Melathorax postice declivis et squama nitentes; squama latere postico multo minus inclinato quam in regina; parum concaviusculo, margine supero subtilissime (microscopice) albo-setuloso medioque leviter emarginato Alae anticae long. 1 1/2 lin. Abdomen longitudine capitis thoracisque, thorace fere duplo latius, selis (ut etiam ceterum corpus), sed minoribus quam in regina, conspersum. Venter basi saepe pallescit.

Kallal & LaPolla (2012) - Measurements (n=4) TL: 3.83–4.04; HW: 0.74–0.78; HL: 0.76–0.96; EL: 0.26–0.28; SL: 0.73–0.79; PW: 0.83–0.92; MW: 0.78–0.80; WL: 1.14–1.31; GL: 1.86–2.05; PH: 0.39–0.44; PFL: 0.69–0.74; PFW: 0.19–0.22. SMC: 4–10; PMC: 4–6; MMC: 3–10; MtMC: 2. Indices: CI: 77–96; REL: 29–33; SI: 76–99; FI: 77–94.

Brown in color, with scapes, mandibles, and leg joints yellowish; mesosoma sometimes lighter brown than head and gaster; cuticle smooth and shiny; body with dense pubescence; macrosetae brown. Head usually longer than broad; scapes surpass posterior margins by first 3–4 funicular segments. Propodeum with short dorsal face and long declivitous face.

Male
Long. 3/4 lin. nitidus fuscus; ore, articulationibus pedum, tarsis et genitalibus testaceis. Setae corporis fere ut in regina. Alae ut in diagnosi feminae; anticae long. 3/4 lin. Squama parva sursum rotundato-quadrata, postice concaviuscula. Abdomen (supra visum) circulare, longitudine vix thoracis. Appendices genitalium vaginis externis angustis distantibus intus curvatis flavido-pilosis, internis tenuibus rectis.

Kallal & LaPolla (2012) - Measurements (n=9) TL: 1.79–2.15; HW: 0.46–0.53; HL: 0.46–0.55; EL: 0.19–0.23; SL: 0.52–0.69; PW: 0.46–0.51; MW: 0.40–0.54; WL: 0.70–0.78; GL: 0.62–0.87; PH: 0.12–0.29; PFL: 0.49–0.57; PFW: 0.10–0.18; PL: 0.20–0.33. SMC: 1–5; MMC: 4–10; MTMC: 2–3. Indices: CI: 74–102; REL: 36–43; SI: 101–125; FI: 92–112.

Overall brown in color, with yellowish-brown scapes, mandibles, and leg joints; mesocoxae and metacoxae sometimes lighter; cuticle smooth and shiny; cephalic, mesosoma pubescent dorsally, except pronotum; gastral pubescence virtually absent; macrosetae brown. Head slightly longer than broad; eyes convex, extending beyond the lateral margins of the head in full face view; antennae bent around segment IV; scapes surpass posterior margin by first 3–4 funicular segments; inner mandibular margin long and straight; basal angle approximately 90°; masticatory margin with one subapical tooth and large apical tooth, sometimes with additional denticles. Mesosoma enlarged to accommodate flight muscles; in lateral view, pronotal margin short and straight; propodeum with equally long dorsal and declivitous faces. Genitalia: parameres laterally oriented, triangular, curving inward distally; digiti angled ventrally; cuspides reaching about half the length of the digiti, both with rounded teeth where they meet; aedeagal valve triangular, teeth absent; ninth sternite becoming broader into a triangular shape proximally, with thin, blunt-ended lateral apodemes and a long 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.