Crematogaster scutellaris

An extremely common, arboreal species reported from the Maghreb to western Russia (Rigato & Toni, 2011).

Identification
A member of the Crematogaster scutellaris group.

Head shining yellowish red contrasting with the brown alitrunk and dark gaster. Antennae 11 segmented. Length: 3.5-5.0 mm (Collingwood 1979).

Distribution
Karaman (2010) - Crematogaster scutellaris is distributed in Italy, Austria, France, Iberian Peninsula and south Germany (Hölzel, 1966; Collingwood & Yarrow, 1969; Collingwood, 1978; Poldi et al., 1995; Seifert, 1996; Heller, 2004). The species is also found in Croatia on the island of Korčula (Bračko, 2006), and in the southeast Bosnia and Herzegovina on Baba Mtn (Fahringer, 1922). Cobelli (1906) cites Crematogaster scutellaris for Slovenia based on his collection of workers. However, the color pattern of the workers, reddish-brown head, thorax and petiole, and black abdomen, matches the description of C. schmidti. Petrov (2008) cite C. scutellaris for Montenegro, providing no locality data.

Crematogaster schmidti and C. scutellaris are allopatric species. The transgression zone between the two species is the region from Slovenia (east slopes of Julian Alpes) to the Adriatic coast of Croatia (Dalmatia), and the southeast Bosnia and Herzegovina. The two species do not hybridize because no intermediate forms have been found in the transgression zone [the territory of former Yugoslavia] (Atanassov & Dlusskij, 1992). Based on the current distribution of C. schmidti and C. scutellaris, we are expecting C. scutellaris to be found in Slovenia, and rejecting the possibility of the same species being present in Montenegro.

Distribution based on Regional Taxon Lists
Palaearctic Region: Andorra, Austria, Balearic Islands, Bulgaria, Croatia, Denmark, France, Georgia, Germany, Gibraltar, Greece, Hungary, Iberian Peninsula, Israel, Italy, Malta, Montenegro, Portugal, Republic of Macedonia, Romania, Slovenia, Spain, Switzerland, Tunisia, Turkey, United Kingdom of Great Britain and Northern Ireland.

Biology
Collingwood (1979) - This arboricolous species is frequently introduced with cork from South Europe or North Africa and has on occasion established itself temporarily in and around warehouses and cork factories in England.

Frizzi et al. (2015) - Crematogaster scutellaris is commonly found in both natural and human-managed ecosystems across the Mediterranean Basin. Nests are excavated in tree trunks or logs and can host up to several thousand workers. This is a dominant species that influences ant community dynamics and arthropod communities. Previous studies suggested C. scutellaris is monogynous, has polydomous nests and exhibits inter-nest aggressiveness which varies with distance. This study examined nestmate recognition in a large olive orchard near Florence, Italy, from March 2009 to September 2010. Nests were located by banging on the trunk of trees. Resident colonies would respond with a defensive swarm of ants that would emerge from their nest holes. Genetic, chemical (CHCs) and spatial characteristics (from 5 to 175 m distances) were examined and behavioral experiments (5 x 5 battles) performed for a range of within and between colony analyses. Polydomy was confirmed by genetic analysis. Many nests were spread across more than a single tree. Genetic analysis supported there being a single queen per colony, with a core nest containing the queen and a network of satellite nests. Genetic differences between nests were strong but were not correlated with distance. This implies a long distance spatial dispersal strategy during mating and/or prior to colony foundation. Cuticular chemical profiles varied significantly among both nests and colonies. This appeared to be explained by a combination of genetic and environmental factors. Aggression between colonies was uneven, occurring in ~50% of the staged tests. Aggressiveness increased with both spatial proximity and similarity in cuticular hydrocarbon profiles among colonies, suggesting a “nasty neighbor” effect.

Bordoni et al. (2018) experimentally showed how Crematogaster scutellaris workers exposed to the same pathogen as their mother exhibited increased survival compared to control workers. These results suggest social immunity, passed on from one generation to the next, can be important for social organisms. "They "found, for the first time in ants, that founding queens exposed to a non-lethal dose of an entomopathogenic fungus produce offspring with an increased resistance to the same pathogen. This phenomenon did not reveal apparent costs to foundresses and workers, at least with respect to their survival and reproductive output."

Guiliani et al. (2019) observed this species foraging on extrafloral nectaries of the invasive Reynoutria x bohemica (Polygonaceae) in Tuscany. The habitats examined were river banks and disturbed habitats.

Nomenclature

 *  scutellaris. Formica scutellaris Olivier, 1792: 497 (w.) FRANCE. Mayr, 1855: 469 (q.m.). Combination in Crematogaster: Mayr, 1855: 469; in C. (Acrocoelia): Emery, 1922e: 143; in C. (Crematogaster): Bolton, 1995b: 166. Senior synonym of rediana, rubriceps, ruficeps: Mayr, 1855: 469; of haematocephala: Roger, 1863b: 36; of grouvellei, lichtensteini: Bernard, 1967: 164; of corsica, degener: Casevitz-Weulersse, 1990a: 137. Material of the unavailable name hybrida referred here by Baroni Urbani, 1964a: 4. See also: Emery, 1912e: 652; Stitz, 1939: 128; Baroni Urbani, 1971c: 79; Kutter, 1977c: 88; Radchenko, 2007: 33. Current subspecies: nominal plus alii, nigra (unresolved junior homonym), tenuispina.
 * haematocephala. Formica haematocephala Leach, 1825: 291 (w.q.m.) FRANCE. Junior synonym of scutellaris: Roger, 1863b: 36.
 * rediana. Myrmica rediana Gené, 1841: 399 (w.) ITALY. Junior synonym of scutellaris: Mayr, 1855: 469.
 * rubriceps. Myrmica rubriceps Nylander, 1849: 44 (w.) ITALY (Sicily). Junior synonym of scutellaris: Mayr, 1855: 469; Radchenko, 2007: 33.
 * ruficeps. Acrocoelia ruficeps Mayr, 1853a: 147 (w.) AUSTRIA. Junior synonym of scutellaris: Mayr, 1855: 469.
 * grouvellei. Crematogaster scutellaris var. grouvellei Bondroit, 1918: 115 (w.q.) FRANCE. Junior synonym of scutellaris: Bernard, 1967: 164.
 * lichtensteini. Crtematogaster scutellaris var. lichtensteini Bondroit, 1918: 114 (w.) FRANCE. Junior synonym of scutellaris: Bernard, 1967: 164.
 * corsica. Crematogaster scutellaris var. corsica Santschi, 1921b: 435 (w.) FRANCE (Corsica). Junior synonym of scutellaris: Casevitz-Weulersse, 1990a: 137.
 * degener. Crematogaster scutellaris var. degener Santschi, 1937e: 310 (w.) TUNISIA. Junior synonym of scutellaris: Casevitz-Weulersse, 1990a: 137.