Lasius speculiventris

Identification
Closely related to Lasius umbratus, but differing by its very sparse gastric pubescence and tendency toward denser cephalic and appendage pilosity.

Key to Lasius workers, queens, males

Distribution
Widespread in the eastern United States and seems to be most common in the Great Lakes district.

Distribution based on Regional Taxon Lists
Nearctic Region: United States.



Biology
This species nests under a variety of conditions. At Volo it was taken in natural hummock in marshy ground near a larch-sphagnum bog. At New Lenox two colonies were found in a pasture, deep in the sod under rocks set in a dry ditch bank. At the E. S. George Reserve a huge colony was found beneath a layer of red woody soil under a dead standing tree in oak-hickory woods; the ants had galleried the roots of the dead trees into thin partitions. (Wilson 1955)

Nomenclature

 *  speculiventris. Lasius speculiventris Emery, 1893i: 641 (w.m.) U.S.A. Wilson, 1955a: 172 (q.). Combination in L. (Chthonolasius): Emery, 1925b: 235. Subspecies of umbratus: Wheeler, W.M. 1910e: 237; Wheeler, W.M. 1917h: 167. Revived status as species: Creighton, 1950a: 423.

Worker
Wilson (1955) - (1) Central area of exposed second gastric tergite, exclusive of the posterior strip, almost completely devoid of pubescence of any kind and with only a few widely scattered erect hairs, its cuticular surface extremely smooth and shining. The third and posterior tergites are usually very similar in this respect to the second, but the first tergite may have the bare area limited to a median longitudinal strip as narrow as one-fourth the width of the gaster (E. S. George Reserve, Mich.). Series at the opposite extreme (Caldwell, N. J.; Volo, Ill.; Chicago, Ill.) have no pubescence whatsoever on the gastric tergites except for thin zones along the posterior tergital margins.

(2) Standing appendage and cephalic pilosity ranging from extremely dense (scapes and legs covered with abundant, predominantly subdecumbent to erect hairs, and the margin of the head seen in full face from the mandibular insertions to the anterior borders of the eyes with more than 20 erect hairs) to less dense than the extreme hirsute form of Lasius umbratus (hairs on the scapes and legs mostly appressed-decumbent and seldom standing, and only one or two erect hairs along the genal contour). The type series exhibits the first extreme, and the Urbana, Ill., series, the second. There is no evident correlation between the density of the cephalic and anterior appendage pilosity and the density of the gastric pubescence.

Queen
(1) Gastric pubescence as in worker. Dorsal surfaces of second, third, and fourth tergites exclusive of the posterior strips almost completely devoid of pubescence. Dorsal surface of first tergite covered with appressed pubescence except for a thin, longitudinal, median strip about 0.15 mm. in width.

(2) Scapes and legs hairier than in all North American umbratus seen but still within range of variation of Eurasian series, Scape densely covered with short, predominantly decumbent hairs. Femora and tibiae with dense appressed pilosity and scattered short but outstanding decumbent hairs.

(3) In all other aspects. apparently identical to umbratus. Extreme HW rang.e 1.53-1.62 mm.

Male
(1) At least the median longitudinal fourth of the second and posterior gastric tergites devoid of pubescence, its cuticular surface smooth and shining; in the type series the entire dorsal gastric surface is devoid of hairs and strongly shining.

(2) Standing hairs more abundant on the head and alitrunk than in North American umbratus. In the type series, but not in another series from Ramsey Co., Minn., erect hairs are abundant along the genal contour viewed in full face.

(3) Extreme HW range 1.00-1.21 mm.

Type Material
Wilson (1955) - LECTOTYPE. By present selection, a worker in the Museum of Comparative Zoology labeled "Caldwell, N. J., Sept. 11 '88." Synnidotypes are in the Museum of Comparative Zoology, Emery Collection, American Museum of Natural History, and United States National Museum.