Leptothorax acervorum

Monogynous and polygynous colonies are present in Japan, but even in polygynous colonies only one of the queens has functional ovaries and lays eggs (Ito, 1991), which is (“functional monogyny”). Three socially parasitic ant species are known to associate with L. acervorum in Europe, but none are yet known to occur in Japan. (Terayama and Onoyama 1999)

Identification
Terayama and Onoyama (1999) - Total length of workers around 3-3.5 mm. Head and gaster black; mesosoma, petiole and postpetiole reddish brown, their dorsa blackish brown; legs brown. Antennae 11-segmented; scapes short, not reaching posterior margin of head in full-face view. Pro- and mesonotal dorsa depressed in profile. Propodeal dorsum weakly convex. Propodeal spines longer than wide in side view, with acute tips. Petiolar node high, triangular; anterior margin sloping steeply forwards in profile; peduncle obscure.

Collingwood (1979) - Reddish to brownish yellow with the head, antennal club and dorsal surface of gaster darker. Dorsa of petiole nodes and femora frequently infuscated. Antennae with eleven segments. Head longitudinally striate, alitrunk rugose and gaster smooth. Propodeal spines strong. Mesopropodeal suture distinct and depressed. Tibiae and scapes with numerous erect hairs. Length: 3.8-4.5 mm.

This is a comparatively large and robust species easily recognized by the abundant suberect appendage hairs in all castes. The species tends to darken in colour from south to north varying from bright yellowish brown to nearly black, the darker samples occurring chiefly in high mountain areas, peat bogs and in the arctic north but with no clear break in colour gradation to the dark form sometimes referred to as the variety nigrescens Ruzsky (1905).

Distribution
Northernmost Scandinavia to mountains of South Europe and from Spain to Japan (Collingwood 1979).

Terayama and Onoyama (1999) - In Japan this species is distributed in the lowlands of Hokkaido and mountainous areas of Honshu, Shikoku, and Kyushu. In central Honshu L. acervorum is found at 1,350-2,590 m above sea level (Sonobe, 1979), at 1,900-1,980 m on Mt. Ishizuchi in Shikoku (Takechi, 1960a, 1960b; Sonobe, 1979), and at 1,740 m on Mt. Kujyu, Kyushu (Sonobe, 1979).

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Oriental Region: India. Palaearctic Region: Andorra, Armenia, Austria, Belarus, Belgium, Bulgaria, China, Croatia, Czech Republic, Democratic Peoples Republic of Korea, Denmark, Estonia, Finland, France , Georgia, Germany, Greece, Hungary, Iberian Peninsula, Iran, Japan, Kyrgyzstan, Latvia, Liechtenstein, Lithuania, Luxembourg, Mongolia, Netherlands, Norway, Poland, Republic of Korea, Republic of Moldova, Romania, Russian Federation, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom of Great Britain and Northern Ireland.



Biology
Collingwood (1979) -This species nests in small isolated colonies of 25 to 60 individuals with one or several queens; worker-queen intercastes are frequent. It is found nesting in open moorland in peat, rock crevices and under stones and in woodland areas on fallen tree trunks, rotten branches, stumps or under bark. The workers forage singly, predating small insects or scavenging insect corpses. It has not been observed to tend aphids, is non-aggressive and avoids combat with other ants. Alatae occur in the nests in June and July and have been observed flying and mating on high ground in July.

Nomenclature

 *  acervorum. Formica acervorum Fabricius, 1793: 358 (w.) DENMARK. Latreille, 1798: 49 (q.m.); Wheeler, G.C. & Wheeler, J. 1955b: 21 (l.). Combination in Leptothorax: Mayr, 1855: 436; in L. (Mychothorax): Ruzsky, 1904a: 288. Senior synonym of lacteipennis: Nylander, 1846a: 936; of kamtshaticus: Kupyanskaya, 1986b: 96; of orientalis: Kupyanskaya, 1990: 137; of nigrescens, superus: Radchenko, 1995a: 23. Material of the nomen nudum melanocephala referred here by Mayr, 1855: 411. Current subspecies: nominal plus vandeli. See also: Donisthorpe, 1915d: 147; Stitz, 1939: 158; Tarbinsky, 1976: 86; Kutter, 1977c: 128; Atanassov & Dlussky, 1992: 130; Terayama & Onoyama, 1999: 75.
 * lacteipennis. Myrmica lacteipennis Zetterstedt, 1838: 452 (m.) SWEDEN. Junior synonym of acervorum: Nylander, 1846a: 936.
 * nigrescens. Leptothorax acervorum var. nigrescens Ruzsky, 1905b: 614 (w.) RUSSIA. Subspecies of acervorum: Ruzsky, 1936: 94; Pisarski, 1969b: 297. Junior synonym of acervorum: Radchenko, 1995a: 23.
 * superus. Leptothorax (Mychothorax) acervorum var. superus Ruzsky, 1905b: 614 (w.m.) RUSSIA. [Later misspelled as superbus by Ruzsky, 1936: 94.] Junior synonym of acervorum: Radchenko, 1995a: 23.
 * kamtshaticus. Leptothorax (Mychothorax) acervorum subsp. kamtshaticus Ruzsky, 1920: 77 (w.) RUSSIA. Junior synonym of acervorum: Kupyanskaya, 1986b: 96.
 * orientalis. Mychothorax acervorum subsp. orientalis Kuznetsov-Ugamsky, 1928b: 31 (w.) RUSSIA. Junior synonym of acervorum: Kupyanskaya, 1990: 137.