Caste Terminology

General
The term “caste” is often used to mean either the physical or behavioural and physiological phenotype of a eusocial individual, or both (Hölldobler & Wilson 1990: Glossary). Some authors, e.g., Buschinger & Winter (1976, 1978), define castes according to function alone, whereas others (e.g., Peeters & Crewe 1984, Peeters & Crozier 1988) prefer a merely morphological definition. CROZIER & BUSCHINGER (1987) have suggested that each author might clearly state what meaning the terms would have in his or her paper. Polymorphism of female reproductives in ants has been revised by Heinze (1998).


 * BUSCHINGER, A. & CROZIER, R.H. 1987: Towards a unified reproductive biology of the Hymenoptera. In: EDER, J. & REMBOLD, H. (Editors): Chemistry and biology of social insects.- J. Peperny, München, pp. 251-252.


 * BUSCHINGER, A., WINTER, U. 1976: Funktionelle Monogynie bei der Gastameise Formicoxenus nitidulus (NYL.) ( Hym., Form.). Insectes Sociaux 23, 549-558.


 * BUSCHINGER, A. & WINTER, U. (1978): Echte Arbeiterinnen, fertile Arbeiterinnen und sterile Wirtsweibchen in Völkern der dulotischen Ameise Harpagoxenus sublaevis (NYL.)  (Hym., Form.). Insectes Sociaux 25, 63-78.


 * HEINZE, J. 1998: Intercastes, intermorphs, and ergatoid queens: who is who in ant reproduction? Insectes Sociaux 45, 113-124.


 * HÖLLDOBLER, B. & WILSON, E.O. 1990: The Ants. – The Belknap Press of Harvard University Press, Cambridge, MA, 732 pp.


 * PEETERS, C. & CREWE, R. 1984: Insemination controls the reproductive division of labour in a ponerine ant. Naturwissenschaften 71, 50-51.


 * PEETERS, C. & CROZIER, R.H. 1988: Caste and reproduction in ants: not all mated egg-layers are “queens”. Psyche 95, 283-288.

Dichthadiiform
The special form of ergatoid queen peculiar to army ants, always wingless and with very large gaster to accommodate massive egg production.

Gamergate
In many ponerine ants, fertilized, ovipositing worker that assumes the reproductive function of the queen caste.

Intercast
Morphologically somewhere between the fully developed alate gynomorph and the ordinary ergatomorph (worker). Reproductive organs usually not well developed, spermatheca often lacking, infrequently reared in colonies with ordinary gynomorphic queens and ergatomorphic workers. With a functional caste definition the term makes little sense.

Intermorph
Morphologically somewhere between the fully developed alate gynomorph and the ordinary ergatomorph (worker). Usually the reproductive organs are well developed and the specimens are able to assume queen function. Sometimes co-occurring with gynomorphs in species with queen polymorphism.

Major worker
The largest subcaste of worker ants; sometimes also referred to as a "soldier" because often specialized for defense, but may also be specialized to crush seeds, as in species of Pheidole.

Minor worker
A member of the smallest of the worker subcaste.

Monomorphic
The worker caste occurring in only a single morphological form or size class.

Polymorphic
Refers to the coexistence of two or more subcastes within the same caste, often serving different functions, and connected through a gradual series of intermediates in a nonisometric growth curve; individuals of distinctly different proportions occur at the extreme ends of the variation range.

Queen
Any mated and egg-laying female of a eusocial insect colony (according to a functional definition of castes). – Any alate (or, in ants after mating) dealate female of a eusocial insect species with fully developed pterothorax, notwithstanding its reproductive status or function (according to a morphological definition of castes).

Queen polymorphism
Both gynomorphic and intermorphic queens co-occur within one species though not necessarily within one nest. In a couple of species queen polymorphism has a genetic basis (e.g., Harpagoxenus sublaevis, Myrmecina graminicola)

Replete
A worker ant whose crop is greatly distended with liquid food and functioning as a living reservoir; this food is made available to other colony members by regurgitation.

Soldier
A worker subcaste specialized for colony defense, often with enlarged head and/or mandibles. May also be specialized for crushing seeds.