Myrmicaria brunnea is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of ant

Ant

Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...

. They have a distinctive down-curved abdomen

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

 and spines on the thorax

Thorax

The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...

.

Description

The following taxonomic description is based on C. T. Bingham

Charles Thomas Bingham

Charles Thomas Bingham was an Irish military officer and entomologist.Bingham’s military career began in India where he was a soldier in the Bombay Staff Corps and later with the Bengal Staff Corps...

:

• worker: Chestnut-brown, shining ; mandibles finely and closely, head and thorax more or less widely, longitudinally striate ; the nodes of the pedicel smooth or only slightly rugulose ; abdomen polished and smooth ; pilosity long, abundant, reddish yellow, slightly oblique on the antennae and legs. For the rest the characters of the genus.
• queen: resembles the worker in colour; the mandibles are more coarsely striate, the clypeus is smooth, the front between the antennae and the cheeks longitudinally striate, the head posteriorly on the vertex and lateral angles coarsely reticulate. Thorax : the pronotum somewhat vaguely and transversely and the mesonotum posteriorly longitudinally striate ; anteriorly the latter is smooth and polished, the scutellum rugose, the metanotum irregularly striate rugose, including the basal portion of the metanotal spines. Pedicel :the nodes rugulose, opaque ; abdomen smooth, polished and shining. Wings hyaline ; nervures brownish.
• male: Light chestnut-yellow, the apical margins of the abdominal segments more or less broadly brownish black ; head and thorax somewhat densely pubescent, in places rugulose, giving them a dull subopaque look ; head on each side of the ocelli longitudinally striate. Some few striae on the mesonotum posteriorly and on the basal portion of the metanotum, traces of the same on the apical face of the latter. Pedicel obscurely rugulose, subopaque ; abdomen smooth, shining, but not highly polished. Wings flavo-hyaline ; nervures yellowish.

Var. subcarinata, Smith, is slighter, more slender and lighter in colour, often nearly smooth ; it occurs in Bengal, Burma, and Tenasserim, and extends down to Borneo. The colour and the rugosity, as well as the pilosity, vary very much ; but, so far as a very long series has enabled me to judge, the one species with
many slightly differing local races extends through India, Ceylon, and Burma.