Myrmeciites

M. herculeanus was described from a single side of a compression fossil found at the Middle Ypresian McAbee Fossil Beds, Kamloops Group, near Cache Creek, British Columbia. The incomplete specimen numbered UCCIPR L-18 F-974, is currently preserved in the paleontology collections housed at the Thompson Rivers University, Kamloops, British Columbia. Archibald, Cover, and Moreau coined the specific epithet "herculeanus" from the Latin name "Hercules" in reference to the notably sturdy and large morphology of the type specimen, and after the divine hero Heracles in Greek mythology, who was the son of Zeus and Alcmene.[8] The species is discernible from the other species of Myrmeciinae by its notably larger size, the worker caste ant is estimated at over 20 millimetres (0.79 in) in life. Its size is comparable to ants in the genus Ypresiomyrma. The shape of the petiole, a narrow waist that is located between the mesosoma and gaster is distinct from other species and is similar in structure to the genus Prionomyrmex though the shape and size of the mandibles are distinct. Overall, M. herculeanus was assigned to Myrmeciinae due to its mandible length, despite them being poorly preserved, and due to the appearance of its petiole and propodeum. The legs are long in comparison to its body length, and the gaster is robust. It is unknown if the species had a sting, due to the preservation of the specimen. The size of the single known worker is larger than any of the studied queens; as Myrmeciinae queens are slightly larger than the other castes in a species, this indicates M. herculeanus is most likely a distinct species. Due to the incomplete nature of the type specimen, the species was placed in Myrmeciites.[8]

The second species described from the McAbee Fossil Beds is M.(?) goliath and as with M. herculeanus, it is known from one specimen, though both the part and counterpart are known for M.(?) goliath. The holotype is housed in the Thompson Rivers University, Kamloops, collections as UCCIPR L-18 F-999 and UCCIPRL-18 F-1000 for each side respectively.[9] The species name "goliath" was chosen by Archibald, Cover and Moreau in reference to the mythological Goliath, due to the notable size of the ant.[9] The holotype specimen is a partial worker or queen which is incomplete, with a notable portion of the gaster missing. The species can be separated from other ants by the large size, the holotype approaching 3 centimetres (1.2 in). The only other Eocene ants in this size range are members of the genus Titanomyrma, that were formerly placed in Formicium.[9][10] M.(?) goliath is distinguishable from Titanomyrma by the shape and structure of the antennae and length of the legs, which are notably shorter in Titanomyrma. The head is very round and flattened, compound eyes are present and the mandibles are small, less than half the length of the head. The head is also small in proportion to the mesosoma. The legs are large and long, and a poorly preserved petiole is known.[9] Most of the specimen is preserved in fine detail, but some characters are so poorly preserved that the exact placement of M.(?) goliath within Myrmeciinae cannot be confirmed. Only future fossils that are better preserved can clarify the position of M.(?) goliath.[11]

Unlike the other described Myrmeciites species, M.(?) tabanifluviensis is the only species not from the McAbee Fossil Beds. The holotype, currently deposited in the Courtenay and District Museum paleontology collections as 2003.2.10 CDM 034 was recovered from the "Horsefly shale", part of an unnamed formation, outcropping near the town of Horsefly, British Columbia. The specimen is incomplete with both the head and portions of the mesosoma and gaster missing. The adult had an estimated length in life of over 1.5 centimetres (0.59 in).[12] The right portions of the legs are well preserved while the left legs are missing with two metatibia spurs, one of which is long and the other is short and narrow. Due to the incomplete nature of the specimen and position of the preserved portions, the gender is not identifiable, though the presence of wings indicates it to be a reproductive adult. The small size of the specimen, with a fore-wing length of approximately 12 millimetres (0.47 in), separates this species from other members of the British Columbia Myrmeciinae. The type locality for the species, near the Horsefly River, was the basis for Archibald, Cover and Moreau choosing the specific epithet tabanifluviensis, combined with the horsefly genus name Tabanus, the Latin word fluvius meaning "river" and the sufix -ensis meaning "origin" or "place".[12] The justification of placing this ant in Myrmeciites is due to incomplete preservation.[13]

Two additional specimens were placed within the form genus but not into a specific species. The Courtenay and District Museum specimen 2003.2.9 CDM 03 a&b is a 2 centimetres (20 mm) long partial male recovered from the Falkland site, near Falkland, British Columbia. The generally robust nature of the specimen excludes it from the genus Avitomyrmex, but the details needed for placement between the genera Ypresiomyrma and Macabeemyrma are not present. The Stonerose Interpretive Center specimen "SR 05-03-01" is a possible queen or worker which would have been an estimated 1.5 centimetres (15 mm) long in life. Due to the lateral preservation of the specimen, most characters for placing the specimen into one of the defined species are obscured or absent. The specimen was recovered from outcrops of the Klondike Mountain Formation north west of Republic, Washington.[14]

Archibald, S.B.; Cover, S. P.; Moreau, C. S. (2006). "Bulldog Ants of the Eocene Okanagan Highlands and History of the Subfamily (Hymenoptera: Formicidae: Myrmeciinae)" (PDF). Annals of the Entomological Society of America. 99 (3): 487–523. doi:10.1603/0013-8746(2006)99[487:BAOTEO]2.0.CO;2.