Acanthomyrmex

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Acanthomyrmex
Acanthomyrmex luciolae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Acanthomyrmex
Emery, 1893
Type species
Acanthomyrmex luciolae
Diversity
19 species
(Species Checklist)

Acanthomyrmex-luciolaeHUMCZ001L4.jpg

Acanthomyrmex luciolae

Acanthomyrmex-luciolaeHUMCZ001D4.jpg

Specimen Label

Evolutionary Relationships



Cardiocondyla



Ocymyrmex






Nesomyrmex



Xenomyrmex





Terataner




Atopomyrmex



Cataulacus










Carebara



Diplomorium






Melissotarsus



Rhopalomastix






Calyptomyrmex



Tetramorium





Cyphoidris



Dicroaspis










Aretidris



Vollenhovia





Dacetinops



Indomyrma








Crematogaster



Meranoplus






Lophomyrmex




Adlerzia



Recurvidris






Stereomyrmex




Trichomyrmex





Eutetramorium




Royidris




Malagidris



Vitsika








Huberia



Podomyrma





Liomyrmex



Metapone













Kartidris



Mayriella





Tetheamyrma




Dacatria



Proatta









Dilobocondyla



Secostruma






Acanthomyrmex



Myrmecina





Perissomyrmex



Pristomyrmex









some Lordomyrma



Propodilobus





Lasiomyrma




[some Lordomyrma




Ancyridris



some Lordomyrma









Paratopula




Poecilomyrma




Romblonella



Rotastruma








Gauromyrmex



Vombisidris





Temnothorax




Harpagoxenus




Formicoxenus



Leptothorax













Based on Ward et al. (2014) and Blaimer et al. (2018).

Eguchi, Bui and Yamane (2011) -Acanthomyrmex species nest in dead twigs and wood fragments, and under or between stones. Colonies of Acanthomyrmex glabfemoralis contain a single dealate normal queen, or instead contain single or multiple dwarf queens, while colonies of A. humilis contain ergatoid queens only (Eguchi et al. 2008). Acanthomyrmex glabfemoralis and Acanthomyrmex humilis gather seeds (Eguchi et al. 2004, Eguchi pers. observ.).

Photo Gallery

  • Danum Valley, Sabah
  • Acanthomyrmex ferox, small natural colony with two soldiers, a couple of workers and the queen looking into the picture from below, surrounded by fig seeds that serve as food. 1-II-1998 Ulu Gombak, leg. A. Buschinger.

Identification

Eguchi, Bui and Yamane (2011) -Workers of Vietnamese species have the following features (see also Moffett 1986; Eguchi et al 2008): Worker dimorphic; frontal lobe reduced, in full-face view only partially concealing the torulus; frontal carina present, usually conspicuous; antennal scrobe present, usually conspicuous; anteromedian margin of clypeus weakly convex with a shallow median emargination in major; anteromedian margin of clypeus always armed with 2 to several processes in minor; median clypeal seta reduced or absent in major, but always present in minor; lateral portions of clypeus not forming a conspicuous ridge in front of torulus in major, but raised into a ridge in front of torulus in minor; mandible in major massive, edentate or armed with a few indistinct teeth on masticatory margin; mandible in minor broadly triangular, and armed with 5–10 small to tiny teeth in addition to relatively conspicuous apical and preapical teeth; antenna 12-segmented, with 3-segmented club; eye moderately developed; mesosoma short and robust especially in major; promesonotal suture absent dorsally; metanotal groove obsolete or shallow dorsally; propodeum armed with a pair of long spines; propodeal lobe well developed, angulately produced poster¬odorsad; petiole pedunculate anteriorly and with distinct node; postpetiole much shorter than petiole; suture between first gastral tergite and sternite basally in the form of a rounded M-shape; postpetiole articulated at base of the M.

The minor worker of Acanthomyrmex is similar to the worker of Pristomyrmex, but in the latter the antenna is 11-segmented, the masticatory margin of the mandible is almost vertical to the basal margin and 3-, 4- or 5-toothed, and the suture between first gastral tergite and sternite is not in the form of a rounded M-shape.

Keys including this Genus

 

Keys to Species in this Genus

Distribution

Distribution and Richness based on AntMaps

Biology

Acanthomyrmex species nest in cavities in dead twigs and wood fragments, under or between stones and in litter on the forest floor, and their colony size is usually small (Moffett 1985, Terayama et al. 1998, Eguchi et al. 2004, Yamada et al. 2018). Colonies are often aggregated in patches. Because reproduction by ergatoid queens is dominant in some species of Acanthomyrmex (Terayama et al. 1998, Yamada et al. 2018), such aggregation of colonies may be caused by the low dispersal ability of the ergatoid founder. Species in this genus predate on fig seeds, and soldiers (e.g. Acanthomyrmex careoscrobis) are specialised to crack such seeds (Moffett 1985).

Castes

Morphology

Worker Morphology

 • Antennal segment count 12 • Antennal club 3 • Palp formula 4,3 • Total dental count 7-12 (minor worker), 0-3 (major worker and queen) • Spur formula 1 simple, 1 simple • Eyes present • Scrobes present • Caste dimorphic

Male Morphology

 • Antennal segment count 13 • Antennal club 0 • Palp formula 4,3 • Total dental count 6-8 • Spur formula 1 simple, 1 simple

Karyotype

Species Uncertain

  • Acanthomyrmex sp.1: n = 11 (Malaysia) (Goni et al., 1982).
  • Acanthomyrmex sp.2: 2n = 22 (Malaysia) (Goni et al., 1982).
  • Acanthomyrmex sp.3: n = 11, 2n = 22 (Malaysia) (Imai et al., 1983).
  • Acanthomyrmex: 2n = 24 (Sarawak) (Tjan et al., 1986).

All Records for Genus

Taxon Haploid Diploid Karyotype Locality Source Notes
Acanthomyrmex 22 Malaysia Goni et al., 1982
Acanthomyrmex 24 Sarawak Tjan et al., 1986
Acanthomyrmex 11 Malaysia Goni et al., 1982
Acanthomyrmex 11 22 Malaysia Imai et al., 1983

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • ACANTHOMYRMEX [Myrmicinae: Myrmecinini]
    • Acanthomyrmex Emery, 1893a: cclxxvi. Type-species: Acanthomyrmex luciolae, by subsequent designation of Bingham, 1903: 191.
    • [Acanthomyrmex also described as new by Emery, 1893f: 244].

Description

Moffett (1986) - Dimorphic myrmicine ants. Worker castes with trunks short and stout, convex dorsally in profile except for prominent propodeal spines (and usually with cylindrical humeral spines in minor workers); antennae 12-merous, with scape having a thin, plate-like flange encircling its base. Major caste with head huge, articulating with trunk ventrally so that the vertex of the head projects back over the trunk. Minor workers with a prominent medial hair on anterior border of clypeus.

Minor Worker Small to moderate sized ants (total length 2.7 to 5.0 mm), usually with little size variation within a series. Head large (ca. 50% wider than trunk), wide (CI at least slightly greater than 100); head width 0.70 to 1.23 mm. Cephalic sculpture typically densely foveate, occasionally alveolate or virtually smooth. Eyes moderately large (length of eye in full-face view 17 to 25% of head length), oval, and strongly convex; located mediolaterally, with the distance between anterior margin of eye and mandible bases representing 24 to 34% of head length. Antennal fossae far apart, at anterior margin of head. Feeble scrobe usually present dorsad to eyes for all or at least the basal part of the scape (bent downwards apically in some species to accommodate part of the funiculus); the frontal carinae extend back to form the dorsalmost borders of the scrobes. Antennae 12-merous, moderately thick, with a three-segmented funicular club; club about as long as remainder of funiculus excluding basal funicular segment. There is a prominent flange above the basal radical, forming a thin, disc-shaped "base" to the scape.

Clypeus produced back between bases of antennae; posterolateral borders of clypeus raised to form trenchant ridges which border the antennal fossae in front. Clypeus usually with lateral foveae or rugae; anterior margin with several small, well-separated projecting lobes and with a prominent medial hair. Mandibles massive (MI 69 to 92), with a wide, subtriangular blade which curves ventrad toward apex, with the margin having four to ten tiny teeth separated by wide gaps in addition to two relatively prominent apical teeth; dorsal mandibular surfaces feebly punctate and with a very feeble rugulose microsculpture. Maxillary palpi with four segments; labial palps with three (Acanthomyrmex basispinosus and Acanthomyrmex mindanao examined).

Trunk very short and robust, evenly convex in profile, with anterior margin of propodeum not at all impressed dorsally; trunk diminishing in width posteriorly. Pronotum fused with mesonotum; promesonotal suture obsolete. Propodeum invariably bispinose; pronotum generally armed with dorsolateral spines, which are located anterodorsally to the dorsalmost point reached by the groove between the pronotum and mesothorax laterally. Sculpture foveate on pronotum and dorsally on trunk; areolate-rugose on pleura of remainder of trunk, and smooth on declivity of propodeum. Petiole pedunculated in front; node usually with dorsolateral denticles or spines. Postpetiole variable, low and rounded dorsally or with a prominent node; usually rugose. Gaster oval, less wide than head, and longer than deep. Legs moderately long, with hind femora 85 to 148% as long as head; middle and hind tibiae with a single basal spur. Long, erect to suberect pilosity generally dense on head, sparser on trunk, and variable on legs, petiole, postpetiole and gaster; on head hairs mostly arise from foveae.

Major Worker Head enormous, appearing greater in volume than remainder of body, and of a length about twice that of trunk or longer. Foramen located ventrally far from posterior margin of head, with the portion of the head behind the foramen extending back over the trunk; trunk partially hidden within a cavity beneath head posteriorly. Cephalic sculpture foveate (at least on vertex), but with foveae generally small, shallow and sparse relative to those of minor workers. Ocelli lacking; compound eyes similar to those of minor worker, but slightly more anterior on head, and of a length 9 to 14% of that of the head. Antennae similar in size to those of minor workers, and thus much smaller relative to head size; scrobes as described for minors but more prominent, with a shallow recess for basal portion of funiculus typically also present dorsad to eyes. Clypeus smooth, without small projecting lobes along anterior margin, and usually lacking pilosity. Mandibles massive, similar to minors but smaller relative to head size (MI ca. 50 to 60), typically with dorsal masticatory margin worn; with a ventral process shaped like a massive, blunt tooth beneath mandible basally (occasionally present as small denticle in minors). Trunk, waist, and gaster similar to minors, but pronotal spines lacking, and pronotum smooth anteriorly.

Queen Previously undescribed. Head smaller than in major caste, and attached to trunk nearer to posterior margin of head; not projecting back over trunk. Mandibles, antennae and compound eyes similar to worker castes, and (relative to head length) intermediate in length between those of majors and minors; ocelli present. Clypeus as in majors. Mandibles each with a ventral process like those of majors. Trunk very short and stout, quadrate in lateral view; in dorsal view rounded, almost as wide as long. Pronotal spines lacking; propodeal spines present. Scutellum dorsolaterally with short, thick spines projecting posteriorly above propodeal spines; posterior margin of scutellum directly above that of propodeum. Known only for Acanthomyrmex ferox; for further details see ferox description.

Male Previously undescribed. Head broad; eyes similar to those of queen but much larger relative to head size (length about 40% of that of head). Antennal scrobes absent. Antennae 13-merous. Scapes thick, not reaching posterior margin of head, and virtually lacking a basal flange. First and seventh funicular segments very short, about as long as broad, with the segments between them each about a third the length of scape; third and fifth segments somewhat compressed (others cylindrical), the fifth curved; segments beyond the sixth longer, and progressively lengthening distally (terminal segment about 80% of scape length). Mandibles as long relative to head length as in queen or major, but much less massive, only very slightly curved ventrad apically; the six to eight teeth along masticatory margin less reduced than in female castes, and without large gaps between them; ventral mandibular process lacking.

Trunk similar to that of queen, but somewhat longer; mesonotum with an impressed Mayrian furrow; scutellum higher; propodeum lacking spines, pinched laterally below spiracles, and extending out posteriorly beyond back margin of scutellum. Postpetiole with node very low and rounded; postpetiole low, smooth, and more elongate than in females; legs long and slender. Parameres curving sharply ventrad midway along length, with narrow, rounded tips having very short pilosity. Digitus heavily sclerotized, curving strongly ventrad near base, and rounded distally; cuspidal lobes very low and inconspicuous. Aedeagus subrectangular, ventral margin serrate, with tiny, very sharp recurved teeth. Wings as in Pristomyrmex, but with a complete discoidal cell (m-cu vein present).

Male known only for Acanthomyrmex ferox; for further details see description of that species.

Larva Known for two species. The larvae of A. ferox are considerably different from those of Acanthomyrmex notabilis (see Wheeler and Wheeler, 1977, 1983, and in preparation). The differences are strong enough to suggest separation at the generic or even tribal level (Wheeler and Wheeler, personal communication). The alternative is a rapid evolution of the larvae within the genus Acanthomyrmex.

References

  • Ashmead, W. H. 1905c. A skeleton of a new arrangement of the families, subfamilies, tribes and genera of the ants, or the superfamily Formicoidea. Can. Entomol. 37: 381-384 (page 383, Acanthomyrmex in Myrmicinae, Myrmicini)
  • Bingham, C. T. 1903. The fauna of British India, including Ceylon and Burma. Hymenoptera, Vol. II. Ants and Cuckoo-wasps. London: Taylor and Francis, 506 pp. (page 191, Type-species: Acanthomyrmex luciolae; by subsequent designation)
  • Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 255, Acanthomyrmex in Myrmicinae, Myrmecinini)
  • Emery, C. 1893c [1892]. [Untitled. Introduced by: "M. C. Emery, de Bologne, envoie les diagnoses de cinq nouveaux genres de Formicides".]. Ann. Soc. Entomol. Fr. (Bull.) 61:cclxxv-cclxxvii. (page cclxxvi, Acanthomyrmex as genus)
  • Emery, C. 1893h. Voyage de M. E. Simon à l'île de Ceylan (janvier-février 1892). Formicides. Ann. Soc. Entomol. Fr. 62: 239-258 (page 244, Acanthomyrmex also described as new)
  • Emery, C. 1895l. Die Gattung Dorylus Fab. und die systematische Eintheilung der Formiciden. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 685-778 (page 769, Acanthomyrmex in Myrmicinae, Myrmicini)
  • Emery, C. 1912b. Études sur les Myrmicinae. [I-IV.]. Ann. Soc. Entomol. Belg. 56: 94-105 (page 105, Acanthomyrmex in Myrmicinae, Myrmecinini)
  • Emery, C. 1914e. Intorno alla classificazione dei Myrmicinae. Rend. Sess. R. Accad. Sci. Ist. Bologna Cl. Sci. Fis. (n.s.) 18: 29-42 (page 41, Acanthomyrmex in Myrmicinae, Myrmecinini)
  • Emery, C. 1924f [1922]. Hymenoptera. Fam. Formicidae. Subfam. Myrmicinae. [concl.]. Genera Insectorum 174C: 207-397 (page 234, Acanthomyrmex in Myrmicinae, Myrmecinini)
  • Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 244, Acanthomyrmex in Myrmicinae, Myrmecinini)
  • Hölldobler, B.; Wilson, E. O. 1990. The ants. Cambridge, Mass.: Harvard University Press, xii + 732 pp. (page 16, Acanthomyrmex in Myrmicinae, Pheidolini (error))
  • Moffett, M. W. 1986c. Revision of the myrmicine genus Acanthomyrmex (Hymenoptera: Formicidae). Bull. Mus. Comp. Zool. 151: 55-89 (page 55, Revision of genus)
  • Terayama, M., Ito, F. ; Gobin, B. 1998. Three new species of the genus Acanthomyrmex Emery (Hymenoptera: Formicidae) from Indonesia, with notes on the reproductive caste and colony composition. Entomol. Sci. 1: 257-264 PDF
  • Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 139, Acanthomyrmex in Myrmicinae, Myrmicini)
  • 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 663, Acanthomyrmex in Myrmicinae, Myrmecinini)
  • Yamada, A., Ito, F., Hashim, R., Eguchi, K. 2018. Queen polymorphism in Acanthomyrmex careoscrobis Moffett, 1986 in Peninsular Malaysia (Hymenoptera: Formicidae: Myrmicinae), with descriptions of hitherto unknown female castes and males. Asian Myrmecology 10, e010009 (DOI 10.20362/am.010009)