Myrma

The subgenus Myrma Billberg is the most widespread of all the Polyrhachis subgenera, occurring throughout the Indo-Malayan, Oriental, Australasian and Ethiopian regions. It is also the second most speciose subgenus, comprising more than one hundred described species and subspecific forms. (Kohout 2013)

Species Groups
Currently, the Afrotropical fauna of Myrma remains divided into six species groups (alexisi, gamaii, militaris, monista, revolii and viscosa), all restricted to the region, as proposed by Bolton (1973), while the number of species-groups for the Oriental and Australasian fauna has increased to nine. Following the transfer of most of its members to the aculeata-group, the abrupta-group now comprises only a single, namebearing species, Polyrhachis abrupta from Halmahera. The parabiotica-group introduced by Kohout (2006) and the cyaniventris-group established by Sorger and Zettel (2009) each include three species, all apparently endemic to the Philippines, while the vestita-group is restricted to the Indonesian island of Sulawesi. The recently revised continua-group (Kohout 2013) comprises mostly Melanesian elements. The inermis and zopyra species-groups almost equally share the species originally included by Emery (1925) in a single zopyra-group, and both are distributed from Sri Lanka and India across Indonesia and the Philippines. Finally, the relucens-group, the largest and most widespread of the Oriental and Australasian species-groups, comprises a diverse assemblage of species that could conceivably be subdivided into several more morphologically uniform species-groups.

Afrotropical species groups
Rigato (2016) revised the Polyrachis of sub-Sahara Africa. His study retained Bolton's (1973) six species-groups for the region. There is currently a total of 61 species, all considered members of the subgenus Myrma. As for their biology "sub-Saharan Polyrhachis species have a range of nesting habits comparable to that of the whole genus: from forest species, building their nests with silk and plant debris among tree leaves, to ground inhabiting savannah ones. This life style diversity can occur in a single species-group, despite the morphological similarity of its members.


 * Key to Afrotropical Polyrhachis species-groups
 * Key to Afrotropical Polyrhachis species

alexisi
Polyrhachis alexisi species-group

gamaii
Polyrhachis gamaii species-group

militaris
Polyrhachis militaris species-group

monista
Polyrhachis monista species-group

revolii
Polyrhachis revolii species-group

viscosa
Polyrhachis viscosa species-group

abrupta
Polyrhachis abrupta from Halmahera

aculeata
Polyrhachis aculeata species-group

Key to Polyrhachis aculeata species-group workers

continua
Polyrhachis continua  species group

key to Polyrhachis continua  workers

cyaniventris
Sorger and Zettel (2009, 2010); 3 species endemic to the Philippines

Polyrhachis cyaniventris species-group

Key to Polyrhachis cyaniventris species-group workers

inermis
Sri Lanka and India across Indonesia and the Philippines

Polyrhachis inermis species-group

parabiotica
Kohout (2006); 3 species

relucens
The largest and most widespread of the Oriental and Australasian species-groups, comprises a diverse assemblage of species that could conceivably be subdivided into several more morphologically uniform species-groups.

Polyrhachis relucens species-group

vestita
restricted to the Indonesian island of Sulawesi

Polyrhachis vestita species-group

zopyra
Sri Lanka and India across Indonesia and the Philippines

Polyrhachis zopyra species-group

Nomenclature

 *  MYRMA [subgenus of Polyrhachis]
 * Myrma Billberg, 1820: 104. Type-species: Formica militaris, by subsequent designation of Wheeler, W.M. 1911c: 859.
 * Myrma subgenus of Polyrhachis: Forel, 1915b: 106; Forel, 1917: 251; Wheeler, W.M. 1922a: 702, 993; Emery, 1925b: 198.
 * Myrma senior synonym of Hoplomyrmus: Wheeler, W.M. 1922a: 993.
 * Myrma senior synonym of Pseudocyrtomyrma: Bolton, 1973b: 288.
 * Myrma senior synonym of Anoplomyrma: Dorow, 1995: 30.
 * [Although Myrma antedates Polyrhachis, the former has been treated as a subgenus of the latter since Forel, 1917: 251 (see Hung, 1967b: 396 for history). Dorow, Kohout & Taylor, 1997: 236 proposed the precedence of Polyrhachis over Myrma and that precedence was established by the ICZN (Opinion 1919) 1999: 92.]
 * ANOPLOMYRMA [junior synonym of Myrma]
 * Anoplomyrma Chapman, 1963: 258 [as subgenus of Polyrhachis]. Type-species: Polyrhachis (Anoplomyrma) parabiotica, by monotypy.
 * Anoplomyrma junior synonym of Myrma: Dorow, 1995: 30.
 * HOPLOMYRMUS [junior synonym of Myrma]
 * Hoplomyrmus Gerstäcker, 1859: 262. Type-species: Hoplomyrmus schistaceus, by monotypy.
 * [Hoplomyrmus also described as new by Gerstäcker, 1862: 508.]
 * Hoplomyrmus junior synonym of Polyrhachis: Roger, 1861b: 174; Roger, 1863b: 6; Mayr, 1863: 446; Dalla Torre, 1893: 257.
 * Hoplomyrmus junior synonym of Myrma: Wheeler, W.M. 1922a: 993; Emery, 1925b: 198; Bolton, 1973b: 288.
 * PSEUDOCYRTOMYRMA [junior synonym of Myrma]
 * Pseudocyrtomyrma Emery, 1921e: 18 [as subgenus of Polyrhachis]. Type-species: Polyrhachis revoili, by original designation.
 * Pseudocyrtomyrma junior synonym of Myrma: Bolton, 1973b: 288.

Description
Kohout (1989) – The subgenus Myrma Billberg can be characterised by the following combination of characters:

1. Dorsum of mesosoma convex in profile; lateral margins distinct, with margination interrupted only at the sutures.

2. Pronotum armed with a pair of relatively long, straight, more or less anteriorly-directed spines.

3. Propodeum either unarmed or with tubercles or small teeth.

4. Promesonotal suture and propodeal groove distinct.

5. Petiole scale-like, usually armed with a pair of dorsal spines or denticles, each with a laterally oriented tooth or blunt angle below its base.

6. First gastral tergite basally truncated or shallowly concave.

7. Anterior clypeal margin arcuate, often bluntly truncated medially.

8. Mandibles at their bases finely longitudinally striate.

9. Frontal carinae forming sharply raised, lamellate flanges; the area between them relatively narrow.