# Samsum ant

The samsum ant (Brachyponera sennaarensis, formerly known as Pachycondyla sennaarensis) is a species of ponerine ant widely distributed in Africa and the Middle East. A common household pest, the ant is a member of the genus Brachyponera. It was first described by Austrian entomologist Gustav Mayr in 1862. The ant is known for its powerful sting, in rare occasions leading to anaphylactic shock and death.

## Taxonomy

The samsum ant was first described by Austrian entomologist Gustav Mayr in his 1862 book Myrmecologische Studien, and was originally placed in the genus Ponera under the name Ponera sennaarensis. The type locality of the species is Sennar, Sudan. The species was categorized in the Brachyponera genus in 1901 by Italian entomologist Carlo Emery, under the name Brachyponera sennaarensis. Emery designated the ant as the type species of the genus, despite Brachyponera croceicornis being assigned as the type species by him a year prior.
In 1994, Brachyponera was syonymized with genus Pachycondyla, with the ant joining under the name Pachycondyla sennaarensis. In the mid 2010s, Brachyponera was revived to full genus status based on morphological and molecular analysis. The ant was again identified to be part of the Brachyponera genus, under the name Brachyponera sennaarensis. Samsum ants are ponerine ants.

## Distribution

Samsum ants are distributed throughout Africa, the Arabian Peninsula, and Iran. The ants are extensively distributed in Africa, and have been described as the most common ant species in Sudan by Levieux & Diomonde (1978). Originating from Northeast Africa, the species has been found in large populations in Burkina Faso, Cameroon, Democratic Republic of the Congo, Ethiopia, Gambia, Guinea, Iran, Niger, Nigeria, Saudi Arabia, Senegal, Somalia, the United Arab Emirates, and Yemen. It is an invasive species in the United Arab Emirates and Saudi Arabia, threatening endemic Arabian ant species. The species was also found in the United States in 1943. Its vast distribution around urban areas in Africa and Asia has led to its being described as a tropicopolitan and cosmopolitan species, and one of the most abundant animals in human settlements in those regions. Its widespread distribution has been attributed to it being one of the only ponerine species to be omnivorous, and having a flexible diet.

## Description

The samsum ant is 5–6 mm (3⁄16–1⁄4 inch) in length, and the body is dark brown to black-brown in colour, with the antenna, tarsi and tibia red in colour. The ant has a head broader than its mesosoma. Samsum ants are ground-dwelling species unable to climb smooth, vertical walls, as they lack adhesive pads on their tarsi and have small arolium glands. They have straight, pretarsal claws with an average claw tip angle of 56 degrees. Their ventral tarsal surface lack fine hairs. Samsum ants are polymorphic, having three castes: a male ant, a queen ant, and a worker ant. This species of ant is known for the size difference between workers and queen ants, considered rare within ponerine ant species.
The species is known under the common name "samsum ant" in the Middle East. The word "samsum" (Arabic: صمصام) means "sharp sword", likely referring to the ant's stinger, as the ant is known for its powerful stings, in rare cases leading to anaphylactic shock and death. The ants sting humans as a defensive measure, and cases of anaphylaxis caused by the ant's stings have been attributed to the ant globally. This has resulted in the species being termed as a common household pest in several regions, being one of the only ponerine ants to be considered invasive.
The samsum ant has winged male and female forms, with nuptial flights taking place shortly after rain. Large and small workers are found within the colony. In a study in Iran for the Journal of Zoology in the Middle East, researchers found colonies along irrigation ditches in damp grounds. The entrance of such nests were noted as being circular in shape and 3–5 mm (1⁄8–1⁄4 inch) in diameter. Samsum ants have large colonies, averaging at about 1,000 workers per colony. Samsum ants are omnivores and scavengers. They typically prey on small arthropods, including other species of ants, and occasionally larger arthropods such as cockroaches, using their stingers. They also feed on seeds of various plants, a unique behaviour within Ponerinae ants. The samsum ant is noted for its evolutionary transition from a carnivorous diet, like most ponerine ants, to an omnivorous one, incorporating seeds. The ants are flexible in their diet, shifting between granivorous and carnivorous diets, depending on environmental constraints.