Myrmica sabuleti

A host to the Large Blue butterfly (Phengaris arion).

Identification
Radchenko and Elmes (2010) - A member of the sabuleti complex of the scabrinodis species group. This complex contains all species with males having a relatively long scape (equal to total length of 4-4.5 basal funicular segments). The workers may be confused with several species, but generally they are characterized by a quite narrow frons (mean FI 0.33) and a well-developed lobe at the scape base. Males are distinguished from the socially parasitic members of this group, Myrmica hirsuta, Myrmica vandeli and Myrmica bibikoffi, by the absence of long erect to suberect hairs on the head margins.

Collingwood (1979) - Reddish brown. Antennal scapes are sharply angulate with a longitudinal keel running forward from the bend and a more or less massive lateral extension, which in Scandinavian samples is frequently curved up to appear as a large semiupright tooth seen from behind. The petiole node is more rounded and usually less truncate than in Myrmica scabrinodis Nyl. and the epinotal spines are relatively longer but these features are too variable for certain discrimination between the species in all cases. Head Index: 85.6; Frons Index: 36.8; Frontal Lamina Index: 66.5. Length: 4.0-5.0 mm.

Distribution
Europe (to the north until southern Sweden, Finland and Norway), Caucasus; all previous records of this species east of Ural Mts. belong to M. lonae (or any other species in older papers).

Distribution based on Regional Taxon Lists
Palaearctic Region: Albania, Andorra, Austria, Balearic Islands, Belarus, Belgium, Bulgaria, Channel Islands, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iberian Peninsula, Iran, Jersey, Latvia, Liechtenstein, Lithuania, Luxembourg, Montenegro, Netherlands, Norway, Poland, Portugal, Republic of Macedonia, Republic of Moldova, Romania, Russian Federation, Slovakia, Slovenia, Spain, Sweden, Switzerland, Ukraine, United Kingdom of Great Britain and Northern Ireland.

Biology
Radchenko and Elmes (2010) - The ecology of M. sabuleti has been relatively well studied during the last 20 years mainly because of its importance as the primary ant host of Phengaris arion, which figures in Red Data Books throughout Europe (Settele et al. 2005). The average size of nest is important in determining the suitability of a site to support a population of P. arion because Thomas and Wardlaw (1992) showed that it took the entire annual production of a nest of about 350 workers to rear one caterpillar. Also M. sabuleti has evolved interesing mutualisms with other grassland Lycaenid butterflies (e.g. Thomas 1983). It is also the host for several host-specific parasitic Myrmica species: Myrmica hirsuta, Myrmica bibikoffi, Myrmica lemasnei and possibly Myrmica laurae as well as the more generalist Myrmica karavajevi. At this time it is not known why M. sabuleti should be such a good host for various social parasites. Perhaps it is related to the species’ habitat preferences or maybe to social factors, for example compared to other European Myrmica species, M. sabuleti workers generally lay far fewer eggs (Wardlaw and Elmes 1998); also it is somewhat easier to introduce foreign queens into existing cultures (personal observations) and it seems to have symbioses with aphids (see below).

For anyone who has studied their ecology it is hard to see how the female castes of M. sabuleti were ever confused with Myrmica scabrinodis: apart from the obvious morphological differences, they are adapted to living in warmer habitats than M. scabrinodis (e.g. Brian 1964; Brian et al. 1976; Doncaster 1983), both adults and larvae having a lower basal metabolism and larvae grow and develop more slowly than those of M. scabrinodis when reared at the same temperature (Elmes and Wardlaw 1983a) and workers have a longer foraging period (Elmes 1982). Habitats are usually grasslands, where M. sabuleti favour short-turf in northern latitudes and live under quite long grass in southern Europe (Thomas et a!. 1998). In Northwest Europe it could be considered a relict species of the post-glacial optimum that has persisted because of anthropogenic modifications of the natural environment (Thomas 1993). M. sabuleti is not normally considered a woodland species though it can live in open woodland glades, especially in eastern Europe, where summer temperatures are higher. It is often found in mature sand-dune systems, particularly those that have become grassed and are grazed by animals, the types were probably found in such a sandy place, hence its name.

Workers appear to be generalist predator scavengers, like most of the other Myrmica species. There is circumstantial evidence that it might eat the eliasome of Viola seeds. M. sabuleti do not often forage on obvious aphid colonies, more usually it maintains small cultures of aphids, particularly those species that live on the base of the stems at ground level; one can often find these colonies enclosed with soil and a few workers inside guarding and tending the aphids (personal observations). Workers were observed tending colonies of aphids on the underside of leaves of low-growing Clinopodium vulgare (Wood-Baker 1977) and we suspect that M. sabuleti may be more dependent upon such less-obvious associations than previously appreciated. Collingwood (1979) - This is a robust species usually nesting in sun exposed sheltered sites, often in groups of small nests each containing up to a 1000 or more workers with a few queens. It is characteristically larger and more brightly coloured than the similar Myrmica scabrinodis and easy to distinguish in Scandinavia where the scape development is relatively massive equivalent to the form described as var. lonae Finzi. Nests are usually located under stones but unlike M. scabrinodis seldom or never in tree stumps or in boggy land.

M. sabuleti mainly competes for living space with M. scabrinodis at the cooler end of its niche, and with Myrmica specioides and Myrmica schencki at the hotter end. The processes involved in these competitive interactions have been explored in numerical spatial-simulation models. The average numbers of workers per nest varied from 12 - > 4000 in a study of nearly 300 nests censused in southern England; average nest size on acid grassland was smaller (about 150 workers) than nests on chalk grassland (about 370 workers) but the average number of queens per nest in both types of habitat was the same (just over 1 per nest) (Elmes and Wardlaw, 1982a). A more detailed study of the chalk grassland population showed that above-nest vegetation was implicated in determining the size and productivity of the nest (Elmes and Wardlaw 1982b, c). A population living under stones on limestone grassland had much larger more polygynous colonies, averaging about 1200 workers with 15 queens per nest (Elmes 1974b), this was the population that contained the type series of the social parasite M. hirsuta (see Notes for that species above). Seppa (1996) demonstrated lowered levels of relatedness among workers commensurate with all queens actively reproducing. Brian (1972) followed the populations of several individual nests for some years and showed there to be quite a high turnover of queens and workers, one nest studied supported a population of the parasite Myrmica karavajevi. In an appendix to a paper Brian and Elmes (1974) showed that variations in the annual productivity of this population was directly related to changes in the annual insolation.

M. sabuleti has been used quite frequently in comparative studies of chemical ecology (e.g. Cammaerts et al. 1981; Evershed et. al. 1982). In a more recent study of the cuticular hydrocarbons (Elmes et al. 2002) it was shown that M. sabuleti had a rather “simpler” chemical profile than other species, in particular workers had less Dienes and less Di-methyl alcanes than M. scabrinodis, the two species can be easily discriminated by their chemical profiles. M. sabuleti has been used as a model species in studies of food competition and recruitment (De Vroey 1980a; Cammaerts and Cammaerts 1980; Debiseau and Pasteels 1994; Debiseau et al. 1997).

Nuptial flights occur from August to the end of September. Mixed swarms with other Myrmica species are common (Woyciechowski 1990c and personal observations) and where it co-exists with Myrmica lonae mixed flights are normal.

Collingwood (1979) - This is a robust species usually nesting in sun exposed sheltered sites, often in groups of small nests each containing up to a 1000 or more workers with a few queens. It is characteristically larger and more brightly coloured than the similar Myrmica scabrinodis and easy to distinguish in Scandinavia where the scape development is relatively massive equivalent to the form described as var. lonae Finzi. Nests are usually located under stones but unlike M. scabrinodis seldom or never in tree stumps or in boggy land.

Other Insects
This ant has been associated with the butterflies Phengaris arion and a species that has recently been recognized as two distinct species: Polyommatus icarus and Polyommatus celin. Presently it is unclear if this latter association is between Myrmica sabuleti and one or the other of these species, or both (Obregon et al. 2015).

Nomenclature

 *  sabuleti. Myrmica sabuleti Meinert, 1861: 327 (w.m.) DENMARK. Emery, 1908a: 176 (q.); Hauschteck, 1965: 325 (k.); Donisthorpe, 1915b: 258 (gynandromorph). Junior synonym of lobicornis: Dalla Torre, 1893: 111. Subspecies of scabrinodis: Emery, 1908a: 176; Bondroit, 1910: 495; Emery, 1916b: 120; Menozzi, 1922b: 325; Finzi, 1924a: 12; Finzi, 1926: 101; Menozzi, 1936d: 270. Status as species: Bondroit, 1918: 102; Santschi, 1931b: 345; Karavaiev, 1934: 80; Stitz, 1939: 94; Weber, 1939b: 144; Holgersen, 1940: 184; Novak & Sadil, 1941: 79; Bernard, 1967: 117; Baroni Urbani, 1971c: 31; Kutter, 1977c: 68; Arnol'di & Dlussky, 1978: 534; Collingwood, 1979: 54; Seifert, 1988b: 31; Atanassov & Dlussky, 1992: 97. Senior synonym of scabrinodolobicornis: Radchenko, 1994e: 80. See also: Emery, 1895c: 314; Radchenko & Elmes, 2010: 250.
 * scabrinodolobicornis. Myrmica rubra var. scabrinodolobicornis Forel, 1874: 77 (w.q.m.) SWITZERLAND. Subspecies of scabrinodis: Emery, 1921f: 40; of sabuleti: Weber, 1948a: 296. Junior synonym of lonae: Sadil, 1952: 249; of sabuleti: Radchenko, 1994e: 80.

Taxonomic Notes
Ebsen et al (2019) - Myrmica lonae was recently resurrected as a species separate from M. sabuleti (Seifert, 2000), but where our mtDNA data could not find any evidence to support this. No specific M. lonae haplotypes were found in the four sequenced specimens (Figs. 1 and 2), which suggests that they share the same gene pool as M. sabuleti, as most of the samples were from sympatric populations in The Netherlands and Hungary, and the remaining GenBank sequence came from Finland where only M. lonae has been recorded (Seifert, 2000). The similarity between M. lonae and M. sabuleti is remarkable, because all specimens shared the most abundant Cyt-B M. sabuleti haplotype (Fig. 3), whereas established closely related species (Myrmica hirsuta, Myrmica spinosior, Myrmica vandeli) were differentiated with good bootstrap support. The M. lonae phenotype is associated with colder and wetter habitats than typical M. sabuleti (Elmes et al., 1998; Seifert, 2000; Radchenko & Elmes, 2010; JRE, personal observation), suggesting that this may be an ecotype of M. sabuleti. This interpretation is also supported by the fact that M. lonae and M. sabuleti have identical cuticular hydrocarbon profiles, while other Myrmica species examined can be readily separated based on surface chemistry (Guillem, 2014). Given this overall pattern within the M. sabuleti complex, we hypothesise that the Spanish specimen of M. sabuleti may represent yet another cryptic species (the long branch towards the right in Fig. 2).

Etymology
Radchenko and Elmes (2010) - name derived from the Latin word sabulum = sand, sandy soil, to indicate its habitat.