|Formica militaris, now Polyrhachis militaris|
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)
- 1 Species Groups
- 2 Nomenclature
- 3 References
Currently, the Afrotropical fauna of Myrma remains divided into six species groups (alexisi, gamaii, militaris, monista, revoili 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.
Oriental and Australasian species groups
Kohout (2008) - The continua -group is characterised by an evenly convex mesosomal outline and the presence of postocular and lateral ridges on the head. The inermis species-group was introduced by Bolton (1974). Included in the group were several species placed by Emery (1925) within the very similar zopyra-group. Both species-groups include some of the smallest members of the subgenus. The inermis -group is characterised by well developed pronotal spines, a petiole with two short lateral spines and an entire, arcuate dorsal petiolar margin, and by closely approximated frontal carinae producing an extremely narrow central area. In contrast, species included here within the zopyra-group have the pronotal spines reduced to mere teeth, a petiole armed with four, more-or-less distinct teeth and more widely separared frontal carinae and a broader central area. Twenty-seven Sulawesian species of Myrma belong within the relucens species-group, two in the inermis-group and one species each in the continua-and zopyra-groups. In addition, the island also has several endemic Myrma species that constitute a new vestita species-group characterised by a scale-like petiole that lacks spines and has a dorsal margin with only blunt teeth or a shallow median emargination. This petiolar configuration resembles that of Polyrhachis abrupta from Halmahera, but this species differs from those of the vestita-group in having strongly truncate eyes and a distinct carina running from the eyes towards the occipital corners. A petiole lacking dorsal spines is also characteristic of the inermis-group, but its constituent species differ from those of the vestita-group in having their dorsal petiolar margin smooth and entire. In addition, members of the vestita-group are some of the largest species of Myrma, while the inermis-group includes some of the smallest.
Polyrhachis abrupta from Halmahera
Sorger and Zettel (2009, 2010); 3 species endemic to the Philippines
Sri Lanka and India across Indonesia and the Philippines
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.
restricted to the Indonesian island of Sulawesi
Sri Lanka and India across Indonesia and the Philippines
The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.
- 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.
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.
- Kohout, R. J. 2013. A review of the Polyrhacis aculeata species-group of the subgenus Myrma Billberg (Hymenoptera: Formicidae), with keys and descriptions of new species. Australian Entomologist. 40:137-171.
- Billberg, G. J. 1820. Enumeratio insectorum in Museo Gust. Joh. Billberg. Stockholm: Gadel, 138 pp. (page 104, Myrma as genus of Polyrhachis)
- Bolton, B. 1973b. The ant genus Polyrhachis F. Smith in the Ethiopian region (Hymenoptera: Formicidae). Bulletin of the British Museum (Natural History) Entomology. 28:283-369. (page 288, Myrma senior synonym of Pseudocyrtomyrma)
- Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 123, Myrma as subgenus of Polyrhachis [Although Myrma antedates Polyrhachis, the former has been treated as a subgenus of the latter since Forel, 1917:251 (see Hung, 1967:396 for history). Dorow, Kohout & Taylor, 1997:236 proposed the precedence of Polyrhachi)
- Dorow, W. H. O. 1995. Revision of the ant genus Polyrhachis Smith, 1857 (Hymenoptera: Formicidae: Formicinae) on subgenus level with keys, checklist of species and bibliography. Cour. Forschungsinst. Senckenb. 185: 1-113 (page 30, Myrma senior synonym of Anoplomyrma)
- Emery, C. 1925d. Hymenoptera. Fam. Formicidae. Subfam. Formicinae. Genera Insectorum 183: 1-302 (page 198, Myrma as subgenus of Polyrhachis)
- Forel, A. 1915b. Results of Dr. E. Mjöbergs Swedish Scientific Expeditions to Australia 1910-13. 2. Ameisen. Ark. Zool. 9(1 16: 1-119 (page 106, Myrma as subgenus of Polyrhachis)
- Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 251, Myrma as subgenus of Polyrhachis)
- Kohout, R. J. 1989. The Australian ants of the Polyrhachis relucens species-group (Hymenoptera: Formicidae: Formicinae). Mem. Qld. Mus. 27: 509-516,*Kohout, R.J. 2008a. A review of the Polyrhachis ants of Sulawesi with keys and descriptions of new species (Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum. 52:255-317.
- Kohout, R.J. 2008b. A new Polyrhachis (Myrma) vestita-group species from Sulawesi. Zoologische Mededeelingen, Leiden. 82: 297-302.
- Rigato, F. 2016. The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae). Zootaxa. 4088:1–50.
- Robson, S. 2020. Spiny Ants (Polyrhachis). Encyclopedia of Social Insects, pp. 1–6. (doi:10.1007@978-3-319-90306-4_115-1).
- Wheeler, W. M. 1911b. Ants collected in Grenada, W. I. by Mr. C. T. Brues. Bull. Mus. Comp. Zool. 54: 167-172 (page 170, Polyrhachis as subgenus of Myrma)
- Wheeler, W. M. 1911c. Three formicid names which have been overlooked. Science (N. Y.) (n.s.) 33: 858-860 (page 859, 860, Type-species: Formica militaris, by subsequent designation; Polyrhachis as subgenus of Myrma)
- Wheeler, W. M. 1922i. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VII. Keys to the genera and subgenera of ants. Bull. Am. Mus. Nat. Hist. 45: 631-710 (page 702, Myrma as subgenus of Polyrhachis)
- Wheeler, W. M. 1922j. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bull. Am. Mus. Nat. Hist. 45: 711-1004 (page 993, Myrma senior synonym of Hoplomyrmus)