Aphaenogaster umphreyi

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Aphaenogaster umphreyi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Stenammini
Genus: Aphaenogaster
Species: A. umphreyi
Binomial name
Aphaenogaster umphreyi
Deyrup & Davis, 1998

Aphaenogaster umphreyi casent0103612 profile 1.jpg

Aphaenogaster umphreyi casent0103612 dorsal 1.jpg

Specimen Label

This is a subterranean species that lives in sandy areas. It probably emerges only at night. On two occasions in Florida, Deyrup (2016) collected it below rotten stumps, and it is possible that this species preys on subterranean termites, which move freely through the soil of the Florida scrub and sandhill areas where umphreyi lives. There is no known way to collect umphreyi except by digging and sifting, and no nests have been discovered. A specimen was collected in a sunken bowl trap, so pitfall traps may be useful for collecting this species. It remains the least known species of Aphaenogaster in eastern North America. (Deyrup, 2016)

Identification

Deyrup and Davis (1998) - Similar to Aphaenogaster fulva, but differs in having much smaller eyes, shorter propodeal spines, coarser and more extensive sculpture on the head and mesosoma, more convex vertex in frontal view, and reduced hind tibial spurs.

The evidence that we use to establish the species-level distinctness of umphreyi is as follows: 1. A. umphreyi is sympatric with fulva, at least in Putnam and Marion Counties, and probably farther north as well, so umphreyi is not likely to be a geographic subspecies of fulva. 2. There is no overlap in the following structural character states used to distinguish the new species: relatively small eyes; relatively small propodeal spines; heavy zigzag carinae on the sides of the pronotum and on the propodeum; reduced spurs on the middle and hind tibiae. 3. The occurrence of umphreyi in xeric habitats, while fulva (at least in the southeast) is in mesic, often wet sites. 4. The kinds of morphological differences between the two species go far beyond the kinds of intraspecific variation that seem to be directly influenced by environmental conditions in different habitats (e.g.: in xeric habitats Pheidole dentata seems paler, Odontomachus brunneus paler and smaller).

The evidence available suggests that umphreyi and fulva are a closely related species pair. They share exclusively the following character states: coarse sculpture on the head and mesosoma; upward-pointing propodeal spines; strongly elevated, notched anterior edge of the mesonotum. This combination of features brings umphreyi out to couplet 18 in Creighton's key (1950) to Aphaenogaster, but the short propodeal spines produce an impasse.

Color is not a very reliable character in fulva; it is generally dark brown, but we have seen reddish specimens, particularly from its western range. It would still be useful to check reddish brown individuals assigned to fulva in collections to see whether they have smaller eyes and the other characteristics of umphreyi. We have provisionally identified as umphreyi a pair of pale specimens with small eyes collected in Decatur County, Georgia, but have not included them among the paratypes because they are small specimens with much less conspicuous rugae than normal in umphreyi; these specimens are in the Museum of Comparative Zoology, Harvard University.

The reduced hind and middle tibial spurs of umphreyi are quite variable. In some specimens they are absent, in others they are present, but short. The hind tibial spurs, when present, are shorter than the middle tibial spurs. The hind tibial spurs in Aphaenogaster as a whole are remarkably expressive, compared with most ant genera. In Aphaenogaster floridana they are broad and abruptly acuminate. In Aphaenogaster pallida, which also has very small eyes, they are extremely reduced. In Aphaenogaster flemingi Smith, the hind tibial spurs are somewhat reduced, shorter than the middle tibial spurs. In Aphaenogaster tennesseensis, they are much reduced, thick, and sometimes curved. In Aphaenogaster sardoa, and Aphaenogaster senilis, the basal third is noticeably swollen. In Aphaenogaster campana, they are bristle-like. In Aphaenogaster cockerelli (=Novomessor cockerelli), they have apparently been lost, and replaced by enlarged lateral bristles. Aphaenogaster fulva and several other species have evenly tapering spurs. Nobody knows, of course, what ecological and evolutionary factors are affecting tibial spur morphology, but a study of the habits of umphreyi and other species that have unusual spurs might help us understand the function of tibial spurs in ants.

DeMarco (2015) - Aphaenogaster umphreyi is diagnosed by the spines pointing upward from propodeum and the anterior edge of pronotum above mesonotum. They are similar to Aphaenogaster fulva, but have smaller eyes and smaller hind tibial spurs. The last four antennal segments are not lighter in color.

Deyrup (2016) - This species is distinguished from all other species of eastern North America by its tiny eyes, which are about the same width as the last segment of the antenna. This is a reddish brown, subterranean species that seems most closely related to Aphaenogaster fulva, but the resemblance could be superficial (Deyrup and Davis 1998).

Keys including this Species

Distribution

Florida

Deyrup (2016) - This species is known only from Florida and Georgia, but might have a wider range, as it is difficult to collect. In Florida, umphreyi is known from Highlands, Marion, Alachua, Putnam, Liberty, and Okaloosa counties. It has been collected in Emanual County in Georgia.

Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).


Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Deyrup and Davis (1998) - Aphaenogaster umphreyi may be almost entirely subterranean in habits, and if it does emerge, it may do so at night. All the specimens were collected underground, either in sand under a thick layer of dead leaves and roots, or under piles of litter and trash. The senior author has spent hundreds of hours over the last 14 years prowling scrub habitat at the Archbold Biological Station, without seeing a single specimen of umphreyi in the open. The small eyes and pale color of umphreyi are consistent with a subterranean life. There are no sexuals associated with workers of umphreyi, but we believe that we may have collected an unassociated queen. Carroll (1975) states that queens of fulva are easily distinguished by the "heavily rugose mesothoracic epistemite and stemite." The worker-associated queens we have seen from Florida, South Carolina, Maryland, and Arkansas seem to agree with this description, the rugosity consisting of long, gently undulating longitudinal rugae on a granulate background. We have one dealate queen from Archbold Biological Station (where fulva is unknown) that has zigzag rugae on the mesothoracic episternite and reduced spurs on the hind and middle tibiae. The eyes and propodeal spines arc not reduced. The specimen was collected in a window trap in Florida scrub habitat in November, 1987.

Nothing is known about umphreyi other than it is a subterranean inhabitant of sandy uplands of the southeast, it is difficult to collect, and it appears to be closely related to fulva. We have no long series showing intraspecific variation, no associated sexuals, no details of its geographic range, and no information on diet or behavior. Until myrmecologists develop an effective method for finding colonies, this will remain one of our most obscure species of Aphaenogaster.

Castes

The males of this species have yet to be collected.

Nomenclature

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

  • umphreyi. Aphaenogaster umphreyi Deyrup & Davis, 1998: 88, fig. 1 (w.) U.S.A.

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

Description

Worker

Holotype: head length (anterior edge of clypeus to occiput) 1.15; head width (above eyes): 0.95; malar space (-distance from lower edge of eye to mandible in lateral view): 0.38; length of eye: 0.15; distance from propodeal spiracle to tip of propodeal spine: 0.31.

In frontal view. head with convex vertex; coarse reticulate rugae covering dorsum and sides of head, including occiput; venter of head with prominent carinae diverging from midline. Mandible, antenna, and clypeal area resembling those of fulva.

Mesosoma with strongly raised rugae on the pronotum, mesonotum, and propodeum, these rugae zigzagging, not smoothly undulating, except less elevated and more undulating on pronotal di sc. Propodeal spine short, compared to that of fulva, strongly upturned, approaching a right angle with long axis of propodeum. Legs generally similar to fulva, including transverse ridges on front coxae, except hind and middle tibial spurs reduced, shorter than width of basitarsus on respective legs.

Petiole and gaster similar to fulva, except petiole with more conspicuous rugae.

Color reddish brown, legs and gaster yellowish brown.

Type Material

Holotype worker: Florida, Putnam Co . 3 miles east of Melrose. 20 Aug. 1995 (Lloyd R. Davis), Ordway Preserve. sandhill habitat, nest in ground, at base of small oak; deposited in Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts.

Paratypes: Florida: 22 workers from nest series of holotype; same site and collector as holotype: 1 worker: 1 Oct. 1995; 1 worker: 24 Feb. 1995; 1 worker: 27 Aug. 1995; 1 worker: 6 Sept. 1996; 2 workers: 14 Sept. 1996; 2 workers: 3 Mar. 1995. One worker. Highlands Co., Archbold Biological Station, 16 May 1988 (M. Deyrup), sifted from sand, Florida scrub habitat; I worker: Highlands Co. Sebring. 11 Mar. 1987 (M. Deyrup). Red Water Lake, Florida scrub habitat; 2 workers: Highlands Co .• Sebring 17 Sep. 1990 (M. Deyrup), Flamingo Villas development. Florida scrub habitat; 10 workers (callows, nest series): Marion Co., 16 Oct. 1990 (M. Deyrup). Ocala Waterway development, Florida scrub habitat; 3 workers: Alachua Co., 5.5 miles west of Gainesville (L. Davis). in soil beside rotten pine log, open oak woodland. 22 Mar. 1992; 6 workers: Highlands Co., Placid Lakes Development (M. Deyrup), I Jan. 1997, Florida scrub habitat, collector's yard, root mat below Quercus inopina.

Deposition of paratypes: 4: Museum of Comparative Zoology. Harvard University; 5: National Museum of Natural History. Smithsonian Ins titution. Washington, D.C.; 5: Florida State Collection of Arthropods. Gainesville; 5: The Natural History Museum. London; 4: Los Angeles County Museum of Natural History; 3: collection of Gary Umphrey. London. Ontario; 2 paratypes: collection of Mark Dubois. Washington, Illinois; 2: collection of Kye Hedlin. Raleigh. North Carolina; 2: collection of William MacKay, El Paso, Texas; 5: collection of Lloyd Davis. Gainesville. Florida; 17: Arthropod Collection, Archbold Biological Station.

Etymology

This species is named in honor of Dr. Gary Umphrey, in recognition of his long labors working to elucidate the taxonomy and phylogeny of the intractable Aphaenogaster rudis group.

References