Key to Iberian Peninsula Messor species

This key is based on specimens

In the Iberian Messor species exists a continuus degree of polimorphism. A group of species (Messor celiae, Messor hispanicus, Messor lobicornis) can be named as monomorphic, as the size of the workers is quite similar to the variation know in Messor. Another group (Messor barbarus, Messor bouvieri, Messor capitatus, Messor marocanus, Messor structor, Messor timidus) is clearly polimorphic. But, as usually happens in Nature when we're trying to dicotomyze reality, there's one species (Messor lusitanicus) with a polmorphism in the middle of these two groups. The degree of polimorphism is a valid characteristic in species diferentiation for some pair of species.

In order to achieve a reliable identification it is advisable to use workers of all sizes, specially majors.

1
''Escapo fuertemente expandido en su base, formando un lóbulo redondeado a lo largo del tramo final del escapo. Color negro. Cuerpo submate debido a una reticulación en toda la superficie corporal. Propodeo anguloso llegando a formar una pequeña espina. Monomórfica''
 * Scape strongly swollen at its base, forming a rounded lobe at the proximal zone of the scape. Colour black. Whole body dull due a reticulation in the whole body surface. Propodeum angulose, sometimes forming spines. Monomorphic ..... Messor lobicornis

''Escapo afinándose uniformemente hasta la base. En caso de presentar un ensanchamiento (Grupo structor), éste es poco conspicuo y comienza en la base del escapo continuando el perfil del mismo en una prolongación más o menos triangular. Monomórficas o polimórficas. Propodeo de varias formas''
 * Scape cylindrical, getting thinner to the base. If a lobe exists (Group structor), this is conspicuous and starts at the base of the scape, continuing the scape profile in a more or less triangular lobe. Monomorphic or polimorphic. Propodeum with various shapes..........2

2
return to couplet .....1 Psamoforo (Pelos largos y en forma de "J" formando una especie de cesta) presente en la gula
 * Psammophorus (long "J" shaped hairs forming a basket) present on the gula.....5

''Gula y mandíbulas con numerosas quetas desiguales y no dispuestos en forma de cesta. Todo el cuerpo con abundante pilosidad de erecta a decumbente''
 * Gula and mandibles with numerous uneven quetae, and not forming a basket. The whole body covered with erect to decumbent pilosity.....3

3
return to couplet .....2

''Clípeo emarginado (excepto en las obreras más pequeñas, cuyo clípeo es muy similar a las del grupo barbarus). En vista frontal, la cabeza presenta quetas erectas, sobre todo el perímetro. Escultura rugosa bien desarrollada''
 * Clypeus emarginated (except in the minor workers, which clypeus is very similar to barbarus group). Head with small erect quetae in frontal view, all over its perimeter. Rugose sculpture well developed .....Messor structor

''Clípeo denticulado en su borde anterior. En vista frontal, la cabeza puede presentar quetas erectas en la parte superior de la cabeza, pero está desprovista de ellas en las genas. Escultura más débil, en particular en la cabeza que puede ser en gran parte lisa''
 * Clypeus denticulated in its anterior margin. The head in frontal view can have erect quetae in the occipital border of the head, but without them on the genae. Sculpture weakler, specially on the head, which can be smooth in its majority .....4

4
return to couplet .....3

Propodeo redondeado en vista de perfil; las obreras mayores alcanzan los 11 mm. y tienen la cabeza de un color rojizo, con el resto del cuerpo negro; las minor presentan el cuerpo completamente negro
 * Propodeum rounded in profile view; major workers reaching 11 mm. and have the head with a reddish tinge, and rest of the body black. Minor workers with the whole body black .....Messor barbarus

''Propodeo de anguloso a bituberculado en vista de perfil; color completamente negro en todas las castas. Ciertos ejemplares major llegan a presentar pequeñas espinas en el propodeo''
 * Propodeum from angulose to bituberculated in profile view; colour black in all of the castes. Some major workers can present small spines on the propodeum .....Messor capitatus

5
return to couplet .....2


 * Propodeum rounded to angulose without clearly shaped spines .....6


 * Propodeum with clearly shaped spines .....Messor lusitanicus

6
return to couplet .....5


 * Unicoloured, brown to black .....7
 * Bicoloured head and gaster brown to black and mesosoma reddish .....Messor marocanus

7
return to couplet .....6


 * First gastral segment without hairs, or, exceptionally in some majors with a maximum of six hairs. Postpetiole profile semispheric .....Messor bouvieri


 * First gastral segment with hairs. Exceptionally in some minima workers of M. timidus can have a bald appeareance. Postpetiole profile otherwise .....8

8
return to couplet .....7


 * Scape with semierect to erect quetae.....Messor celiae


 * Quetae running parallel to the scape .....9

9
return to couplet .....8

.....Messor hispanicus
 * Petiole and postpetiole high, with more or less rounded profile, with a smooth transition between anterior and posterior faces. Monomorphic


 * Petiolar and pospetiolar nodes in triangular shape, not elevated, with a clearly demarcated angle between anterior and posterior faces. Polimorphic .....Messor timidus