University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Center for Systematic Entomology, Gainesville, Insecta Mundi Florida 3-1-1989 Identification and Nesting Sites of North American Species of Dolichoderus Lund (Hymenoptera: Formicidae) Clifford Johnson University of Florida, Gainesville, Florida Follow this and additional works at: http://digitalcommons.unl.edu/insectamundi Part of the Entomology Commons Johnson, Clifford, "Identification and Nesting Sites of North American Species of Dolichoderus Lund (Hymenoptera: Formicidae)" (1989). Insecta Mundi. Paper 464. http://digitalcommons.unl.edu/insectamundi/464 This Article is brought to you for free and open access by the Center for Systematic Entomology, Gainesville, Florida at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Insecta Mundi by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Vol. 3, No. 1, March 1989 1 Identification and Nesting Sites of North American Species of Dolichoderus Lund (Hymenoptera: Formicidae) Clifford Johnson Department of Zoology University of Florida Gainesville, Florida 3261 1 Abstract pretation remained intact for 43 years. Creighton (1950) synonymized Wheeler's subspecific forms The identification of North American Dolichod- into the four above species and again recognized D. erus species by-way-of existing keys is unnecessarily pustulatus as distinct. The taxonomic scenario arbitrary and misdeterminations are likely between returned to the 1886 position and, for the above D. mariae and D. pustulatus, the latter species taxa, remains unmodified. The need for further showing most morphological variation over its literature on the identity of these species requires a range. Diagnoses for the four described species and brief explanation. an undescribed form with a revised key and figures Wheeler's studies had accompanying descrip- are given to aid entomologists working without tions and figures but are now largely unavailable identified voucher specimens. Nest data for species and he employed a taxonomy no longer in use. other than D. pustulatus in the Coastal Plain re- Smith (1918) and Gregg (1944) gave non-illustrated vealed below-ground nests or structures immediate- keys and essentially followed Wheeler's work. ly at the ground sui-face. Colonies of D. pustulatus in Wheeler and Creighton in addition to having differ- Florida and southern Georgia have arboreal nests in ent taxonomic views used different diagnostic char- the cavities of smaller limbs of hardwoods about acters in large part. Creighton's key had no accom- swamps and marshes. No ground nests have been panying descriptions or figures and no later key found and the species may occur in compound nests exists. The Creighton key requires discrimination with another arboreal ant, Camponotus (Colobop- between degrees of sculptural development and, if sis) impressus. These observations identify several unaccompanied by properly determined voucher questions for further study. specimens, is especially unclear in separating D. mariae and D. pustulatus. For sculpture of the Introduction propodeum and mesonotum, couplet three of the key uses "... coarse, deep, close-set foveolae" and "... This paper provides a revised key to the known foveolae, when present, shallow and obscure..." to species of Dolichoderus Lund 1831 occurring in depict D. pustulatus and D. mariae respectively. North America, and summarizes the data on both Actual differences between the species in sculpture distributions and nest sites. An undescribed, north- of the propodeum or epinotum as named by Creigh- eastern species known by limited material is also ton, are less distinct than the couplet suggests. briefly characterized and included in the key but not Further, the key appears to have been written using named. Four species have been described; namely, only northern specimens of D. pustulatus and D. mariae Fore1 1884, D. plagiatus Mayr 1870, D. southern specimens are somewhat different as noted pustulatus Mayr 1886 and D. taschenbergi Mayr below. The author earlier misidentified Florida 1866. These species were thus described by 1886 specimens of D. pustulatus (Johnson, 1986), and and 31 years later Wheeler (1905a, b, 1915, 1916, other specimens in the Florida State Collection of 1917) had revised the group, described several Arthropods are similarly misnamed. The authority subspecific varieties and discussed their natural for those determinations is not given but doubtlessly history. His principle change was to place D. pustu- arose from a similar confusion. latus as a subspecies of D. plagiatus and his inter- Insecta Mundi Since properly identified specimens are restrict- A diagnostic worker description and geographic ed to only a few institutions, a more functional key distribution for each species precedes the key. Hairs is desirable. The key given here groups the charac- portrayed in the figures are drawn slightly thicker ters in a hopefully less arbitrary fashion and is than true proportions so they would not become supported by descriptions and figures. indistinct on reduction; this treatment in no way The generic placement for the North American affects the use of the key. The reader should com- forms has been questioned. Mayr (1886) established pare specimens with both the description and key in the subgenus Hypoclinea including the North reaching determinations. American forms, and the possibility of raising that Data on nests other than observations reported name to a full genus has subsequently appeared in for D. pustulatus in the South were taken from the the literature. Lattke (1986) recently recognized the cited literature. group as a distinct genus in a study concerned with neotropical ants. However, no formal revision or Species Diagnoses description of Hypoclinea as a genus exists and the species Lattke treats are quite unlike our northern Dolichoderus mariae fauna. This paper retains the genus Dolichoderus for the North American forms and, with this usage, Worker Diagnosis: The species is basically bicolored. the type species of the subgenus Hypoclinea is The mandibles, antennae, head, alitrunk, legs, and Dolichoderus quadripunctatus Linnaeus of Europe. petiole are brownish-orange and the first segment of The great majority of specimens coming to the gaster has a variable, anterior band of this light- entomologists' attention are workers. Queens are er color. The remainder of the gaster is dark brown typically taken in association with workers and the to black. Intensity of color varies from callow age to key is designed to identify the worker caste. Males maturity in ants and somewhat through time for are rarely collected and too incompletely known for museum specimens. I have seen museum specimens treatment in a key. Workers of Dolichoderus in of Dolichoderus over 50 years of age, however, with North America may be recognized by the following essentially the same color as found in recently col- characters. Total body lengths range from about 3.5 lected material. Also color interpretation varies. to 4.5 mm. or rarely less with no differences be- Wheeler (1905a) described this species as "... yellow- tween species. The gaster and alitrunk are separated ish blood-red, and gaster black", and also as by a single segment, the petiole. The orifice of the "...bright-red and blue-black bodies". cloaca is a horizontally-oriented slit, not a circular Structurally, a fine granulation sculptures the opening. The surrounding hairs do not form a dis- integument of head, pro- and mesothorax, and faint tinct fringe of rather stiff erect bristles about the depressions or foveolae also occur on the head. This opening. The posterior or declivous face of the sculpture is weak, leaving a superficially smooth, propodeum is distinctly concave in lateral view and shining surface under low to moderate magnifica- the propodeum cuticle is thick, inflexible, and tion. A more distinct granulation sculptures the strongly sculptured. These ants occur mainly in the propodeum where a network of delicate ridges East with the western-most records in North enclose shallow polygon-like depressions. This Dakota and Oklahoma. sculpture is weak leaving a shining propodeum in strong light. The integument of petiole and especial- Materials and Methods ly the gaster is smooth and reflective. No erect hairs exist on head, scapes, or body, one of the more dis- Specimens of the four known species have been tinctive attributes of this species. In dorsal view, the studied from the George C. and J. Wheeler Collec- length of the propodeum distinctly exceeds its width, tion, including material determined by well-recog- Fig. la. The lateral profile of alitrunk as in Fig. 2a. nized authorities on North American ants, namely The integument within the concavity of the decli- M.W. Wheeler, M. R. Smith and W. S. Creighton. D. vous face of propodeum with a series of fine vertical R. Smith of the U.S. National Museum kindly con- ridges or striations; some specimens have a distinct, firmed the determination of recently-collected Flori- centrally-located vertical ridge. A delicate granula- da material of D. pustulatus. The undescebed form tion within the concavity reduces reflectivity often to is known only by a small nest series taken recently a near-opaque state. by J.C. Trager in Massachusetts. Definitions of morphological terms appear in Torre-Bueno (1962) Geographic Distribution: The type locality isvineland, or most standard insect references. New Jersey.