Nylanderia ants are small to medium-sized (generally between 1 and 4 mm in total length) and range in color from pale yellow to black.
Workers Workers are generally monomorphic, although some species are variable in size, with a possible example of worker polymorphism observed in
N. amblyops from Madagascar.
Nylanderia workers can generally be easily distinguished from other formicines based on the presence of six
mandibular teeth, erect macrosetae on the scapes and legs, and paired erect macrosetae on the
pronotum and
mesonotum. These
morphological features are considered
synapomorphies for the genus, and will effectively separate this genus from other genera. Overall, the body shape for most
Nylanderia workers is compact and robust in that the mesosomal regions are generally short (as measured against the long axis of the body) and relatively high when compared to a species such as
Paratrechina longicornis. There are, however, several species where the mesosoma is more elongated, superficially resembling
Paratrechina longicornis. Long erect macrosetae are almost never found on the dorsal face of the propodeum, with one known exception. However, species with an elongated mesosoma or short propodeal macrosetae do possess six mandibular teeth, erect macrosetae on the scapes and legs, and paired erect macrosetae on the pronotum and mesonotum which support their placement within
Nylanderia based on the definition of the genus proposed above. Additionally, when macrosetae are present on the propodeum, they show a pattern generally similar to that found on the pronotum and mesonotum of
Nylanderia, with the macrosetae being numerous and of varying lengths. This is in contrast to related genera, for example
Paraparatrechina, where the macrosetae are limited to a single, distinct pair. Given the differences in the patterns of these macrosetae among these genera, and when considering additional characters as outlined above, LaPolla, Brady & Shattuck 2011 (2011) interpreted the presence of macrosetae on the propodeum within
Nylanderia as having
arisen independently from those observed in other closely related genera.
Queens The main features used to distinguish
Nylanderia queens from other
Prenolepis genus-group genera come primarily from the mandibles and scapes. Like workers,
Nylanderia queens have erect macrosetae on their scapes. However, the macrosetae are often not as distinct as in workers because the macrosetae are often shorter and usually surrounded by a thick layer of decumbent pubescence. When considering genera such as
Euprenolepis and
Pseudolasius in which queens also possess macrosetae on the scapes, differences in mandibular tooth count will distinguish
Nylanderia queens. Five teeth are present in
Euprenolepis queens and five or fewer in
Pseudolasius, while
Nylanderia possesses six (or rarely seven) teeth. In other genera such as
Paratrechina and
Paraparatrechina, the queens have no erect macrosetae on their scapes. For
Prenolepis, if erect macrosetae are present on the scapes, the more posterior placement of the eyes distinguishes them from
Nylanderia.
Males Males of
Nylanderia can be more difficult to distinguish from other
Prenolepis genus-group genera because considerable variation occurs in the genitalic structures at the species level for all genera, and features such as mandibular dentition are not useful since dentition is always reduced in males from that observed in workers and queens (usually to one or two teeth). The scapes can be useful in separating male
Nylanderia from some
Prenolepis genus-group genera since they possess macrosetae similar to those found in workers and queens, but at reduced numbers.
Paratrechina and
Paraparatrechina males, like workers and queens of these genera, never have macrosetae on their scapes. In general,
Nylanderia males have subtriangular
parameres, but similar-shaped parameres are also seen in some species of
Euprenolepis,
Prenolepis, and
Pseudolasius. Both
Euprenolepis and
Pseudolasius have reduced labial and maxillary palp numbers from the more typical six maxillary and four labial
palps observed in other
Prenolepis genus-group genera. For
Prenolepis the separation of males from
Nylanderia is unclear, largely because for the vast majority of
Prenolepis species the males are unknown. Separation of the widespread North American
Prenolepis imparis from
Nylanderia is based on the extremely short scapes (not much longer than the head) that lack macrosetae. ==Species==