Lasius latipes

Nests under stones or logs and in the soil, occasionally with a small mound, in clay soils or fine, sandy loam, with scattered rocks. Lasius latipes is a temporary social parasite of Lasius alienus, Lasius crypticus, Lasius interjectus and Lasius neoniger. It has also been found nesting together with Formica occulta, Lasius sitiens and Myrmica hamulata (Mackay & Mackay, 2002).

Identification
The hairs on the ventral surface of the head of workers are relatively short (0.20 mm or less) and distributed over the entire surface. The hairs on the gaster are also short (0.22 mm or less) and are also scattered over the entire dorsal surface. The apex of the petiole is blunt (when viewed in profile) and convex or straight as seen from the front (rarely slightly concave). (Mackay and Mackay 2002)

Distribution
Coast to coast in southern Canada and the northern half of the continental United States, with southern extensions to Arizona and New Mexico and to South Carolina and Tennessee.

Distribution based on Regional Taxon Lists
Nearctic Region: Canada, United States. Neotropical Region: Mexico.



Biology
Wing (1968) – Of the 259 samples, 44 had data in some form relating to nest structure and location. Nests in the open numbered 25, those in woods and openings in woods 11, while the status of 8 samples was uncertain. With respect to immediate nest-cover, 19 were under stones, 3 associated with wood, 15 without immediate cover, and 7 of uncertain status. Cole (1954) listed 4 New Mexico records of Lasius latipes as A. coloradensis. The data associated with these nests indicated that they were under stones in open grassy areas with scrub oak, pine, and cedar at 7000 to 7200 feet. He listed 9 records under latipes. Of the 7 samples I have seen, 6 were latipes, and 1 coloradensis. The data associated with these samples that seem to apply to latipes is "Nests for the most part beneath stones on dry and moist, grassy, pine slopes. . . . " M. Talbot kindly sent me the 2 or 3 dozen samples that she collected in southern Michigan. The notes relating to these samples are set forth in her paper of 1963. Most nests were on the margins of fields with scattered oak trees. In many cases there was no externally visible evidence of the nest except at flight time. Some nests had immediate cover in the form of stones, wood, or mounds, the latter occurring in thick growths of grass. Kannowski (1956) discussed the structure of several nests in North Dakota; I have seen 6 of his samples. Most of the nests were in the open, under stones. In my own collecting, most nests have been found under stones either in the open, or clearings in woods, or on the borders of woods. This species is often found in sandy areas.

Annual sexual cycle The seasonal cycle of this species is typical of the other species of the genus except Lasius claviger and Lasius interjectus. It rarely nests near human buildings. The dealate queens disappear soon after nuptial flights cease. The cycle covers a relatively short, well-defined portion of the year.

During June and part of July, many of the nest records of sexual forms are based on immatures. Adult alates appear in nests from mid-July on into September. Most nuptial flights begin in late August and continue in September, with a few taking place in October.

Talbot (1963) cited August 2 as the first date for finding adult alates in nests. During a 10-year period, she observed 11 flights. They occurred in the late afternoon, often following rains. Before flights, workers opened up nests by excavation, but the time of digging out varied greatly from nest to nest. It ranged from a few days to several weeks before flight time. One colony was observed digging out on August 1, 1953, but had no real flight before September 8. However, a small number of males flew from this nest on 6 different occasions in abortive flight attempts. An estimate of the number of alates leaving a nest during a regular flight was made on September 4, 1961: the total was 2500 males and 4500 females.

Mackay and Mackay (2002), in New Mexico: Meadows and sagebrush communities, pinyon-juniper, ranging up to deciduous forests and ponderosa pine-riparian and fir forests. Nests together with Myrmica hamulata. One nest also contained Formica occulta, Lasius sitiens and Myrmica hamulata.

Nomenclature

 *  latipes. Formica latipes Walsh, 1863: 311 (w.q.m.) U.S.A. Combination in Lasius: Mayr, 1866b: 889; in Lasius (Acanthomyops): Emery, 1893i: 642; in Acanthomyops: Creighton, 1950a: 431; in Lasius: Ward, 2005: 13. See also: Wheeler, W.M. & McClendon, 1903: 149; Wing, 1968: 98; Smith, D.R. 1979: 1441.

Worker
Wing (1968) – Crest of petiolar scale blunt to very blunt, convex or straight, not emarginate. Standing body' hairs numerous, more or less evenly distributed, most of moderate length. Entire surface of gula covered with 20 to 40 standing hairs, the longest of which measure 1.12 mm or more; those on dorsum of gaster measuring 0.13 mm or more. Fore femur with 12 or more standing hairs.

Standing body hairs simple to finely barbulate, usually fairly numerous on middle and hind femora. Pubescence on head and dorsum of gaster moderate, that on antennal scapes often decumbent to suberect. Body and appendages yellow to brownish yellow, surface of body at least moderately shining.

Queen
Wing (1968) – Head deformed. Scapes and funiculi extremely clavate ; antepenultimate segment of funiculus at least 2.30 times wider than long. Gula with standing hairs covering its entire surface, usually numbering 40 to 80, their maximum length 0.3 5 to 0.80 mm, usually at least 0.40 mm. FW 0.80 to 1.02 mm, FI 58 to 70, genual plates of fore femora large and conspicuous. Petiolar scale large, with crest very blunt, not emarginate. Standing hairs numerous and more or less evenly distributed over head, alitrunk, legs, and petiolar scale, which is covered by 65 to 180 hairs. Pilosity on gaster variable, .ranging from fairly sparse to dense. Pubescence on gaster dense to very dense. Body size large, AL ranging from 3.12 to 3.85 mm, with most specimens measuring at least 3.20 mm.

Standing body hairs simple to finely barbulate, usually fairly numerous on basal segment of gaster, varying on dorsum of other segments from sparse to numerous, and either (1) covering entire surface, or (2) confined to rows on posterior edges of tergites, or (3) with an intermediate pattern. Standing hairs present on hind surface of fore femora, both surfaces of middle femora, and front surface of hind femora. Pubescence on head and pronotum dilute to moderate, that on scutum and scutellum dilute, surface shining. Body color varying from blond to reddish or castaneous brown, with a few specimens fairly dark.

Male
Wing (1968) – Antennal scapes stout, somewhat thickened apically, SL 0.70 mm or less, SI less than 70. Crest of petiolar scale blunt to moderately blunt, usually convex. Paramere with its apex usually truncate. Body size large, AL usually 1.70 mm or greater. Standing body hairs numerous. Entire surface of gula covered with 20 or more standing hairs. All femora quite pilose. Pubescence dense to moderately dense on dorsum of gaster, often suberect on antennal scapes.

Standing body hairs mostly simple, those on dorsum of gaster more or less evenly distributed. Pubescence on head, gaster, and legs moderate to dense, that on antennal scapes usually suberect. Color brown, head darker, appendages lighter.

Hybrids
Wing (1968) described a number of hybrid forms of this species.

Lasius murphyi × latipes hybrid
Five samples from three states: Colorado, Idaho, Iowa.

Worker
Bears a close resemblance to latipes, from which it is not now separable.

Body pilosity more dense than that of most latipes workers, otherwise no consistent differences have been noted.

Queen
Similar to latipes, but differing as follows: Standing body hairs unevenly distributed, bent, tangled, and twisted, but not matted to surface. Crest of petiolar scale more pilose. Gula with most hairs appressed. Antennal scapes and funiculi less clavate. Genual plates of fore femora less pronounced. Fore femora with hairs suberect to erect and mostly flexed, those on other femora fewer in number, mostly appressed to decumbent, and straight. SI over 70. FI 51 or less.

Pubescence on dorsum of gaster dense to moderately dense, elsewhere on body and appendages dilute to moderate. Color brown to yellowish brown.

Male
A typical murphyi male associated with the Idaho collection indicates that this hybrid was produced by the cross, murphyi female × latipes male.

latipes × Lasius claviger hybrid
This sporadic form is recorded in a band from Minnesota and Central Illinois east to New England and New Jersey. It is by far the most common of all known hybrid taxa, most of which are known from only one or two collections.

Worker
Intermediate between latipes and claviger, but having the general appearance of latipes, from which it is not now reliably separable.

Pubescence on gaster dilute to dense. Petiolar scale variable, but usually quite similar to that of latipes. Standing hairs on gula almost invariably cover the entire surface. Length of standing body hairs and body size average and range a little greater than in latipes. Body color yellow to brownish yellow.

Queen
Intermediate between latipes and claviger. Head not or only slightly deformed. Antennal scapes and funiculi decidedly clavate; antepenultimate segment of funiculus greater than 1.55 and less than 2.30 times wider than long. Entire surface of gula covered with from 24 to 40 standing hairs, with maximum length usually less than 0.30 mm. FW 0.50 to 0.75 mm, usually at least 0.55 mm; genual plates of fore femora moderate, not conspicuous. FI 43-54. Crest of petiolar scale usually blunt to very blunt, not emarginate, rarely sharper and feebly emarginate. Scale covered with 50-75 standing hairs. Most standing femoral hairs confined to fore femora.

Pubescence on gaster from very dilute to very dense, that on rest of body usually much less dense, most of body usually shining. Pilosity on gaster variable, but most specimens have standing hairs largely confined to the posterior edges of tergites beyond first. Body color variable, most frequently a medium-dark castaneous brown. Some specimens are lighter yellowish brown, others are a dark grayish brown.

Male
Typical of the males of latipes in all known respects.

latipes × Lasius coloradensis hybrid
When the manuscript of the present revision was nearing completion, I noted that Weber (1935) had reported collecting alpha-latipes queens on September 2, 1931 from Towner, McHenry Co., North Dakota. In this paper on Formica obscuripes, he reported on their collection as follows: "Live workers, males and dealate alpha and beta females of Lasius latipes Walsh were found in digging up an obscuripes nest at a depth of about two feet (61 cm.). They did not seem to be captive and were possibly an independent colony." Upon my request, Dr. Weber sent me a beta queen and 3 "alpha" queens, 1 lacking a head. He was unable to locate the workers and males. The study of these specimens was of particular interest, because I knew of no other alpha queens collected so far outside the known range of claviger. Claviger and coloradensis are so closely related that the previous absence of records of latipes × coloradensis seemed odd, especially since latipes × claviger is our most frequently collected hybrid taxon.

A study of these specimens showed the beta female to be a perfectly typical latipes queen. The three "alpha" females resembled latipes × claviger queens closely enough to pass for small variants of this hybrid. Assignment of these queens to latipes × coloradensis was based both on structural characters, largely metric, and the known ranges of claviger and coloradensis.

Queen
Bears a close resemblance to latipes × claviger, from which it cannot readily be separated.

Ranging and averaging smaller for most metric characters, but with AL, CI, and FI about the same, and SI higher than in latipes × claviger. Minor differences from latipes × claviger in conventional characters are: antennal scapes slightly less clavate, petiolar scale crest a little less blunt, and slight color differences. The head and appendages are light yellowish brown; the rest of the body a darker brown. Only a small proportion of the latipes × claviger queens appear bicolorous; they range and average somewhat darker than latipes × coloradensis.

Type Material
Wing (1968) – Type locality: None stated. Dalla Torre (1893) cited Illinois in addition to Wisconsin (a defective queen described by Mayr, 1866) and New Jersey. Wheeler and McClendon (1903), perhaps in part because of the data in the von Dalla Torre catalogue, stated that Rock Island, Illinois was probably the type locality.

Location of types: None are known to exist despite efforts made to locate the Walsh specimens by the late William Morton Wheeler and others since the turn of the century. For this reason, I am designating a neotype queen. The neotype specimen bears 2 printed labels (Livingston Co., MICH., VIII-25-58, M . Talbot and Edwin S. George Reserve), a written code-label (238Ac-N), and a printed identification label with an added handprinted "NEOTYPE" in red. I wish to thank Dr. Mary Talbot, the collector, for giving me this typical series of latipes; it contains all 3 castes which are consistent with Walsh's descriptions. It is virtually certain that Walsh's specimens came from one of the midwestern states, although the exact locality remains in doubt. Dr. Talbot's collection made in southern Michigan almost certainly originates from the general area where the Walsh types were taken. I am depositing the neotype in the along with another queen, 2 males and 4 workers from the nest series.