Myrmecina

Shattuck (2009) - The myrmicine ant genus Myrmecina contains valid species. These are uncommon ants that are most often encountered in leaf litter samples, generally in forested areas. Colonies are small and occur in soil with or without coverings, between rocks, in twigs on the ground or in rotten wood. While little is known about their biology, some are thought to be predacious on oribatid mites, and it has been suggested that the exceptionally small heads of larval Myrmecina are an adaptation to feeding on the partially opened bodies of these mites (Masuko, 2008). A rare, social parasitic species occurs in nests of Myrmecina americana in North America (S. Cover, pers. comm.).

Identification
Shattuck (2009) - The sides of the head behind the eyes with an elongate ridge or groove on each side which starts at the mandibles, runs the length of the head and ends near the upper corners. In side view, the petiole is low, rounded and barrel-shaped and lacks a distinct node. The propodeum is armed with long spines near the angle as well as short spines or angles near the metanotal groove. The distinctive ridge on the sides of the head behind the eyes combined with the low, rounded petiole will separate these ants from all others in Australia.

Distribution
Ants in this genus are found from southern Canada south to southern Mexico, in Europe and northern Africa, and from India east to Korea and Japan and south into Fiji, the Solomon Islands and Australia. It is apparently absent from Central and South America, sub-Saharan Africa and the Middle East (Guenard, 2009). While relatively common and well represented in Papua New Guinea, this fauna is distinct from that of Australia.

Biology
Okido et al. (2020) - Members of the genus Myrmecina live in rotten wood (Wilson, 1959), soil and litter, or under stones (Ogata & Terayama, 1992). The ants are relatively rare. The biology of species of Myrmecina has been studied in only a few species. Masuko (1994) reported the predatory habits of Myrmecina nipponica and Myrmecina flava, and showed that the ants are specialized predators on oribatid mites. He concluded that the peculiarly elongate head of the larvae is associated with a feeding habit in which they insert the head into the hard oribatid body to consume the contents. The association of oribatid mites with Myrmecina was also observed in tropical Asia (Ito & Takaku, 1994; Aoki & Ito, 1997) where they show symbiosis. The colony size of the ants has been recorded in the limited number of species. Wilson (1959) noted 50 adults in a colony of Myrmecina transversa. Ohkawara et al. (1993) counted 27.4±SD 16.1 adults per colony from 108 samples of M. nipponica. Ito (1996) recorded 66±SD 24 workers and 8±SD 8.4 ergatogynes per colony from 41 samples of Myrmecina species of Java. Ergatogynes are found in some species. Emery (1916), Ohkawara et al. (1993) and Ito (1996) reported that Myrmecina graminicola, M. nipponica and undescribed species of Java have ergatogynes.

Deyrup (2015) - The diet of 2 species of Myrmecina has been studied by Masuko (1994) in Japan. These species are general predators of soil microinvertebrates that have specializations for attacking a particular type of prey, hard-bodied mites of the family Oribatidae. These specializations include serrate and scoop-shaped jaws of the worker, used for peeling open oribatid mites, and the elongate head of the larva, used for reaching into the interior of partially shelled mites. The worker mandibles of North American Myrmecina are similar to those of the Japanese species illustrated by Masuko (1994), and it is probable that North American species, also feed on oribatid mites.

Nomenclature

 *  MYRMECINA [Myrmicinae: Myrmecinini]
 * Myrmecina Curtis, 1829: 265. Type-species: Myrmecina latreillii (junior synonym of Formica graminicola), by monotypy.
 * Myrmecina senior synonym of Archaeomyrmex: Brown, 1971a: 1.
 * ARCHAEOMYRMEX [junior synonym of Myrmecina]
 * Archaeomyrmex Mann, 1921: 448. Type-species: Archaeomyrmex cacabau, by original designation.
 * Archaeomyrmex junior synonym of Myrmecina: Brown, 1971a: 1.

Deyrup (2015) - Most of the described species live in Southeast Asia (Brown 1967) and the Australian region (Shattuck 2009), but there are several northern species that might represent a limited evolutionary radiation associated with temperate Arcto-Tertiary forests. The number of North American species is small but uncertain, in spite of analyses by Smith (1948), Brown (1949, 1951, 1967), Creighton (1950), and Snelling (1965). Brown (1967) recognized 2 species, 1 from Mexico and 1 widespread Nearctic species. A 3rd, apparently parasitic species remains undescribed (Fisher & Cover 2007), and further analysis may support reinstatement of a western species, M. californica Smith. In Nearctic Myrmecina, the chief impediment to taxonomic clarity is intraspecific variability in the widespread species M. americana Emery (Brown 1967).

Worker
Eguchi, Bui and Yamane (2011) - Workers of Vietnamese species have the following features. Worker monomorphic; head in full-face view rectangular, with rounded posterior corners; preoccipital carina extending to ventral surface of head and then forming a longitudinal carina which runs anteriad; frontal carina inconspicuous; antennal scrobe absent; frontal lobe large, covering antennal insertion; median margin of clypeus raised above dorsal surface of mandibular bases, with truncate anterior margin, laterally with a submedian carina from anterior end of frontal lobe to anterior margin of clypeus; carina often forming a submedian tooth; median clypeal tooth often present but not accompanied by an isolated median seta; posteromedian portion of clypeus very broadly inserted between frontal lobes; lateral portion of clypeus often (but not always) modified into a narrow and low ridge or wall in front of antennal insertion; mandible triangular; masticatory margin with 2 distinct apical teeth followed by several teeth or denticles; antennae 11- or 12-segmented, with 3-segmented club; eye small to medium in size; mesosoma short, stout with slightly convex promesonotal dome; promesonotal suture absent dorsally; humeral angle distinct; anterior part of mesopleuron with a well developed flange projecting over base of fore coxa; metanotal groove weak or absent; propodeal spine more or less developed; an additional process or tooth sometimes present in front of each propodeal spine; propodeal lobe present only as a low carina; petiole sessile and lacking distinct node, in lateral view usually (but not always) dorsally with a triangular point or angles at or behind midlength of petiole; postpetiole in dorsal view rectangular; gastral shoulder distinct.