Monomorium ellenarium

The type locality of Monomorium ellenarium is a wild arid steppe located near a sandy beach between the areas of Shuvelyan and Dubendi. It was collected from several locations within the area including near the shore within litter around nests of Cataglyphis nodus and Messor laboriosus and from a nest within a pile of dry grass directly near the entrance to a large M. laboriosus nest. Most curiously, workers were sighted entering and exiting nests of C. nodus, with the much larger, aggressively territorial Cataglyphis ants showing no aggression. When the upper chambers of a Cataglyphis nest were excavated, groups of Monomorium ellenarium workers were also sighted evacuating from food chambers, along with the larger Cataglyphis. This strongly suggests M. ellenarium may cohabitate with Cataglyphis nodus as inquilines, perhaps feeding on food scraps or even consuming the brood of their hosts.

A nest was collected in dry grass, however due to its immediate vicinity of a M. laboriosus colony, we are unable to confidently say whether the species can live independently, or prefers to act as inquilines of the larger ants. Observation of the dry grass nest within captivity over approximately 3 months (contained within a 16x150mm test tube, half-full of water blocked off with cotton, fed raw honey and 1:4 sugar-to-water mix) has currently shown that, despite no individual within the colony showing typical dealate gyne traits, new brood is reared, which suggests the presence of one or several ergatoid gynes. Scarcity of surface plants and lack of sugar-producing mutualistic insects on the surface and stems of plants suggests M. ellenarium may tend to root aphids underground.

Identification
Monomorium ellenarium, a member of the Monomorium monomorium group, only bears some resemblance to Monomorium ruzskyi, described from Kazakhstan and also found in Azerbaijan. It may be easily distinguished from M. ruzskyi by the following:
 * Metanotal crossribs more distinct in M. ellenarium, feebly defined in M. ruzskyi
 * Posterior margin of head possessing several long hairs in M. ellenarium
 * Anterior pronotal margin with pair of longer hairs, pronotum with many shorter hairs
 * Propodeal lobes more distinctly developed
 * Gaster fully covered with long semi-erect to erect hairs
 * Overall body coloration much darker in M. ellenarium than M. ruzskyi

Distribution based on Regional Taxon Lists
Palaearctic Region: Azerbaijan.

Nomenclature

 * . Monomorium ellenarium Shigayev & Snegovaya, 2022: 1198, figs. 1, 2 (w.) AZERBAIJAN.

Type Material

 * Holotype worker. Azerbaijan, Absheron, 40.46541 50.24801, 6.VII.2021 (C. Shigayev); Baku Institute of Zoology, National Academy of Science of Azerbaijan.
 * Paratypes 14 workers, same locality and data as holotype; deposited same as holotype.