''Colobopsis saundersi'', synonym ''Camponotus saundersi'', is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of ant found in

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

and

Brunei Brunei ( , ), formally Brunei Darussalam ( ms, Negara Brunei Darussalam, Jawi alphabet, Jawi: , ), is a country located on the north coast of the island of Borneo in Southeast Asia. Apart from its South China Sea coast, it is completely sur ...

, belonging to the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

Colobopsis ''Colobopsis'' is a genus of ant in the subfamily Formicinae. This genus was first described in 1861 by Mayr and contains 95 species. The type species is '' Colobopsis truncata''. Description As part of Camponotini, ''Colobopsis'' workers ha ...

''. A worker can explode suicidally and aggressively as an ultimate act of defense, an ability it has in common with several other species in this genus and a few other

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...

. The ant has an enormously enlarged mandibular (jaw) gland, many times the size of a normal ant, which produces defense adhesive secretions. According to a 2018 study, this species forms a

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

and is probably related to '' C. explodens'', which is part of the '' C. cylindrica'' group.

Defenses

Its defensive behaviours include self-destruction by

autothysis Autothysis (from the Greek roots ''autos-'' "self" and ''thysia'' "sacrifice") or suicidal altruism is the process where an animal destroys itself via an internal rupturing or explosion of an organ which ruptures the skin. The term was proposed by ...

, a term coined by Maschwitz and Maschwitz (1974). Two oversized, poison-filled mandibular glands run the entire length of the ant's body. When combat takes a turn for the worse, the worker ant violently contracts its abdominal muscles to rupture its gaster at the intersegmental fold, which also bursts the mandibular glands, thereby spraying a sticky secretion in all directions from the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

region of its head. The glue, which also has corrosive properties and functions as a chemical irritant, can entangle and immobilize all nearby victims. Direct observation by Jones (2004) found that ''C. saundersi'' adhesive secretions range from bright white at the end of the wet season to cream or pale yellow in the dry season and start of the wet season. These variations in coloration represent a shift in internal pH, likely due to seasonal changes in diet.

Territorial defense

Autothysis Autothysis (from the Greek roots ''autos-'' "self" and ''thysia'' "sacrifice") or suicidal altruism is the process where an animal destroys itself via an internal rupturing or explosion of an organ which ruptures the skin. The term was proposed by ...

in ''C. saundersi'' is common during territorial battles with other ant species or groups. Territorial weaver ants (''Oecophylla smaragdina'') are known to stalk and attack ''C. saundersi'' for territory as well as for predation. Self-sacrifice of ''C. saundersi'' workers is likely to help the colony as a whole by ensuring that the colony retains its foraging territory. Therefore, such behavior would continue within a population given that the behavior was already genetically present within the majority of workers.

Defense against predation

''C. saundersi'' uses autothysis to defend against predation by other

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose num ...

arthropods ( weaver ants, spiders), which are believed to be the main predatory threat to ''C. saundersi'' for two reasons: * Jones (2004) noted through direct observation that ''C. saundersi'' is "remarkably sensitive" to even slight leaf vibration. * The inherent adhesive qualities of ''C. saundersi''s secretion are more effective in immobilizing the appendages of arthropods as opposed to those of vertebrates. ''C. saundersi'' also uses autothysis to defend against vertebrate predators because the chemicals involved are inedible, which could deter certain predators from engaging this species of ant in the future.

Chemicals

The "toxic glue" of ''C. saundersi'' is predominately composed of polyacetates, aliphatic hydrocarbons, and alcohols. Branched-skeleton lactones and methylated isocoumarins produced in the hindgut function as trail pheromones, while straight-chain hydrocarbons and esters produced in the Dufour's glands act as alarm pheromones in ''C. saundersi'' and related species. Jones, et al. (2004) identified the following chemicals within the secretion:

Phenols In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (— O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds ...

* m-cresol (traces found), a corrosive compound * 2,4-Dihydroxyacetophenone * 2-Methyl-5,7-dihydroxychromone * Orcinol (traces found) Aliphatics *

Undecane Undecane (also known as hendecane) is a liquid alkane hydrocarbon with the chemical formula CH3(CH2)9CH3. It is used as a mild sex attractant for various types of moths and cockroaches, and an alert signal for a variety of ants.Hölldobler B, Wils ...

* 2-Heptanone (traces found)

Terpenoid The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes ...

s *

Citronellal Citronellal or rhodinal ( C10 H18 O) is a mono terpenoid aldehyde, the main component in the mixture of terpenoid chemical compounds that give citronella oil its distinctive lemon scent. Citronellal is a main isolate in distilled oils from the ...

* Citronellol * Citronellic acid * Isopulegol * (6R)-(E)-2,6-Dimethyl-2-octen-1,8-dioic acid Both 2,4-Dihydroxyacetophenone and 2-Methyl-5,7-dihydroxychromone are phenolic ketones which cause the pH-dependent color changes of the secretion. (6R)-(E)-2,6-Dimethyl-2-octen-1,8-dioic acid is an acyclic monoterpene previously undocumented in insects. However, the chemical is well known to be a urinary

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, ...

in mammals, with overproduction resulting in toxic

acidosis Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma. The term ''acidemia'' describes ...

in various species.

Gallery

References

External links

* Photos of the ant. {{Taxonbar, from=Q1940969 Colobopsis Hymenoptera of Asia Endemic fauna of Borneo Insects of Brunei Insects of Malaysia Ant Insects described in 1889 Taxa named by Carlo Emery