Lasius minutus

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Lasius minutus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Lasiini
Genus: Lasius
Species: L. minutus
Binomial name
Lasius minutus
Emery, 1893

Lasius minutus casent0104880 profile 1.jpg

Lasius minutus casent0104880 dorsal 1.jpg

Specimen labels

Lasius minutus nests in bogs and fens. Its nests can be fairly large mounds approaching half a meter in height. It is a thought to be a temporary social parasite of Lasius americanus and Lasius pallitarsis as well as the host of the temporary social hyperparasite (i.e., a parasite of a parasite), Lasius speculiventris. Despite its scientific name, the workers are not unusually small, but the queens are. (Ellison et al., 2012)

At a Glance • Temporary parasite  
 

Identification

Wilson (1955) - A distinctive North American species most easily recognized by the small size and unusual pilosity of the queen. (See Lasius bicornis for a more detailed comparison with that species.)

Ellison et al., (2012) - In New England, Lasius minutus is most easily confused with the similarly hairy Lasius subumbratus. But the hairs on the gaster of L. minutus are very long – longer than the hind tibia is wide – whereas the hairs on the gaster of L. subumbratus are much shorter. (Ellison et al., 2012)

Keys including this Species

Distribution

This is an eastern species that lives throughout eastern North America, south to Virginia, and west to Indiana. It has been collected only a few times throughout New England. (Ellison et al., 2012)

Distribution based on Regional Taxon Lists

Nearctic Region: Canada, United States (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Notes accompanying specimens records indicate that Lasius minutus prefers to nest in sphagnum bogs and swampy meadows but will also move into open, dry forest. It has been taken most often in mounds or masonry domes in open areas, and only once (Steuben Co., Ind.) in a log. Brown (pers. commun.) has supplied me with complete notes on his Pennsylvania collections. South of Oxford, near the Pennsylvania-Maryland border, he found a population of this species nesting in masonry domes on the open grassy floor of a tongue of pitch pine woods. These domes measured between about 8 and 18 inches in height and about 2 feet in base diameter, had peculiar bulging sides, and were overgrown with short grass. Similar domes were found in a population at Ottsville along the border of an old pasture and oak-hickory woods. At both localities workers were rather scarce in the nests, and at Ottsville some of the domes were inhabited by Formica fusca instead.

A clue to the host species of minutus is supplied by the following note accompanying a series in the United States National Museum: "N. J./Aug. 15 '85/in hickory stem with Lasius americanus." The nesting site is one typical for americanus, and the determination in this case was probably correct. (Wilson 1955)

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • minutus. Lasius umbratus subsp. minutus Emery, 1893i: 641 (w.q.m.) U.S.A.
    • Combination in L. (Chthonolasius): Ruzsky, 1914a: 61.
    • Subspecies of umbratus: Wheeler, W.M. 1906b: 13; Wheeler, W.M. 1910e: 241 (redescription); Wheeler, W.M. 1916k: 172.
    • Subspecies of bicornis: Emery, 1925b: 233; Creighton, 1950a: 421.
    • Status as species: Wilson, 1955a: 180 (redescription); Smith, D.R. 1979: 1438; Bolton, 1995b: 224; Coovert, 2005: 126; Ellison, et al. 2012: 194.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Wilson (1955) - Similar to Lasius umbratus in habitus, but smaller and with distinctive pilosity and petiole shape.

(1) Apparently averaging and ranging smaller than umbratus; extreme PW range 0.52-0.69 mm.

(2) Entire body covered with long, coarse standing hairs, the longest on the alitrunk and gastric tergites at least 0.6 X as long as the maximum width of the hind tibia midpoint and usually much longer. At the same time, the scapes and tibiae completely bare except for a few decumbent hairs along the flexor margins of the tibiae. Pubescence abundant and strongly appressed.

(3) The petiole, measured in frontal view from the level of the dorsal border of the posterior foramen to the level of the dorsolateral corners, longer than its maximum width in frontal view, and usually with a distinctive shape: tapering from the broadest level (just above the foramina) to the dorsal crest and often expanding again just at the level of the crest; the dorsal margin distinctly but shallowly emarginate (Pl. 2, Fig. 4).

(4) The scape rounded in cross-section.

Queen

Wilson (1955) - (1) Smaller than umbratus and Lasius bicornis. HW of all available series ranging 1.02-1.17 mm,

(2) Entire body covered with long, coarse hairs, the longest on the first two gastric tergites longer than the greatest width of the hind tibia at its midlength. Scapes completely bare of standing hairs; tibiae bare except for a few decumbent hairs along the flexor margins of the hind tibiae.

(3) Petiole in frontal view shallowly and angularly emarginate, with very broadly rounded dorsolateral corners.

(4) The scape rounded in cross-section.

Male

(1) Smaller than umbratus and other umbratus complex members. HW range of limited sample measured 0.80-0.92 mm.

(2) Long, coarse standing hairs abundant over body surface, the longest on the clypeus exceeding 0.15 mm., or greater than one-sixth the head width; the longest on the first gastric tergite 0.15 mm., or 1.6 X the maximum width of the hind tibia at its midlength.

Type Material

Wilson (1955) - SYNTYPES. Three nidotopotype workers in the Museum of Comparative Zoology ("N. J./Aug. 25 '85/Pergande") correspond well to syntype workers borrowed from the Emery Collection ("Kittery Point, Me./Aug. '91/no. 285"). I have declined to designate a lectotype because of the good possibility that this former series was not in Emery's hands at the time of original description, but there can be no doubt that the name has been correctly placed.

References

  • Ellison, A.M., Gotelli, N.J., Farnsworht, E.J., Alpert, G.D. 2012. A Field Guide to the Ants of New England. Yale University Press, 256 pp.
  • Emery, C. 1893k. Beiträge zur Kenntniss der nordamerikanischen Ameisenfauna. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 7: 633-682 (page 641, worker, queen, male described)
  • Emery, C. 1925d. Hymenoptera. Fam. Formicidae. Subfam. Formicinae. Genera Insectorum 183: 1-302 (page 233, Subspecies of bicornis)
  • Ruzsky, M. 1914a [1913]. Myrmekologische Notizen. Arch. Naturgesch. (A)79(9 9: 58-63 (page 61, Combination in L. (Chthonolasius))
  • Smith, D. R. 1979. Superfamily Formicoidea. Pp. 1323-1467 in: Krombein, K. V., Hurd, P. D., Smith, D. R., Burks, B. D. (eds.) Catalog of Hymenoptera in America north of Mexico. Volume 2. Apocrita (Aculeata). Washington, D.C.: Smithsonian Institution Press, pp. i-xvi, 1199-2209. (page 1483, see also)
  • Wheeler, W. M. 1910h. The North American forms of Lasius umbratus Nylander. Psyche (Camb.) 17: 235-243 (page 241, see also)
  • Wilson, E. O. 1955a. A monographic revision of the ant genus Lasius. Bull. Mus. Comp. Zool. 113: 1-201 (page 180, raised to species)