Friday, July 1, 2011

Identification and Distribution of Amblyoponinae Subfamily


These three genera represent the subfamily Amblyoponinae in North America. All of the members have a poorly defined postpetiole that connects to the gaster with a large surface area. They tend to be specialized predators and, as that implies, are equipped with with a stinger and well defined mandibles.

Prionopelta antillana (2) SE (Florida)

Stigmatomma degeneratum Mexico, Costa Rico
Stigmatomma oregonensis SW, NW
Stigmatomma orizabanum SW, Mexico
Stigmatomma pallipes (2) SW, SC, SE, NC, NE
Stigmatomma trigonignathum SE
Stigmatomma zwaluwenburgi HA


Key
These are rarely encountered by the general public. Encountering these ants can perhaps be a mark of achievement for ant enthusiasts. Stigmatomma pallipes is by far the most common and widely distributed member of this family. Reproductives have not been found for most species but it's likely queens are similar looking to the workers in appearance. Males are perhaps more often encountered but to which species they belong to can be puzzling.

Stigmatomma pallipes (2) SW, SC, SE, NC, NE
The most common and wide spread species in Temperate and subtropical parts of North America. Nests have been found in rotting wood and stumps. Morphologically a good sign of this species is the mandibles widen in the middle with a curve on the inside along the teeth.


Stigmatomma oregonensis SW, NW
Eyes... though incredibly hard to make out on all Amblopone species, are distinctly larger, especially on queens. Mandibles are even in thickness with 9 or 10 teeth.

Stigmatomma zwaluwenburgi HA
The only member of this genus found in Hawaii. How it got there and where it's really from are still unknown as far as I can tell. This ant is small at around 2mm long and paler than most other species.


Stigmatomma trigonignathum SE
Thinner than A. pallipes. Mandibles are wide in the middle too, but more exaggerated and fleshed out. The curves follow the lower head margins more before curving back to the tips of the mandibles.


Stigmatomma orizabanum SW, Mexico
Nest have been found undertones in fields or forests, typically at elevations around 2700 and 2800 feet. Local flora comprises mostly of temperate tree species, especially Carpinus (Hornbeam) and Pines. (It's likely Hornbeam distribution continues down into Mexico where this ant is found.) Morphologically this ant is said to be smaller and paler than most other Amblyopone. However A. degenerata is even paler. Both species are around 2mm long or less.

Stigmatomma degeneratum Mexico, Costa Rico
A ghostly white color and relatively few teeth identify this species.


Prionopelta antillana (2) SE (Florida)
This species is only found in Florida. Unlike Amblyopone this genus is only represented by one species in the US. They differ from that genus by having smaller mandibles with only 3 teeth while the former has lots of teeth. The scape and antenna proportions differ as well; they're clubbed. There's probably differ in other ways too but most of the scientific work about them is written in Spanish. They are normally from South America and it is strange they haven't been reported on various islands such as Costa Rico or Jamaica. These are specialized predators that nest in both soil and in dead wood. Colonies are small, fewer than 1000 ants. 


Sources

Brown, W. L. 1949. A new American Amblyopone, with notes on the genus (Hymenoptera: Formicidae). Psyche 56: 81-88.

Brown, W. L. 1960. Contributions towards a reclassification of the Formicidae. III. Tribe Amblyoponini (Hymenoptera). Bulletin of the Museum of Comparative Zoology of Harvard College 122: 145-230.

Haldeman, S. S. 1844. Descriptions of insects, presumed to be undescribed. Proceedings of the Academy of Natural Sciences of Philadelphia 2: 53-55.

Williams, F. X. 1946. Stigmatomma (Fulakora) zwaluwenburgi, a new species of ponerine ant from Hawaii. Proceedings of the Hawaiian Entomological Society 12: 639-640.

No comments:

Post a Comment