Myrmecia imaii

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Myrmecia imaii
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmeciinae
Tribe: Myrmeciini
Genus: Myrmecia
Species group: pilosula
Species: M. imaii
Binomial name
Myrmecia imaii
Taylor, 2015

Myrmecia imaii is known only from extreme southwest Western Australia: south and SE of Perth, east to Esperance, seldom more than a few km from the coast.


M. imaii is the only species of the Myrmecia pilosula complex found in WA.

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: -33.39° to -34.59°.

Tropical South

Distribution based on Regional Taxon Lists

Australasian Region: Australia (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.


Taylor (2015)

All records of M. imaii are from the “High Rainfall” and “SE Coastal Provinces” of the “South Western Australian Floristic Region” defined by Hopper and Gioia (2004) and Hopper et al. (1996). Heterick (2009) reported the species from the recognized Botanical Districts of Esperance Plains, Jarrah Forest, Mallee and Warren. The fact that its relatives at species-complex level are of eastern Australian provenance implies that Jack-jumpers must previously have ranged or dispersed across southern Australia.

This is the species recorded as Promyrmecia pilosula by Clark (1951) from Albany (confirmed by MVMA voucher specimens), Denmark and Mundaring [-31 54, 116 10], the last locality extends the range indicated by the above records, and was a prime collecting site to Clark (who collected ants widely in the south-west, where he resided for many years). He commented that this species “is quite common in Albany and surrounding district, but it is rare further north” (1951: 204).



The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • imaii. Myrmecia imaii Taylor, 2015a: 517, figs. 19-21 (w.) AUSTRALIA (Western Australia).
    • Type-material: holotype worker, paratype workers (number not stated).
    • Type-locality: holotype+paratypes Australia: Western Australia, N Denmark (-34 8, 117 21), HI89-005, -007, HI89-009, HI91-001-003, 005, 008 (no further data).
    • [Note: no date or collector’s names are given for the type-material; collection code of holotype is not given individually.]
    • Type-depositories: ANIC (holotype); ANIC (paratypes); AMSC, BMNH, CASC, MCZC, MHNG, MVMA, QMBA, SAMA, TMHT, WAMP (“paratypes or type-compared vouchers”).
    • [Myrmecia imaii Imai, Taylor & Crozier, 1994: 146. Unavailable name (published without designation of type-material).]
    • Distribution: Australia.

Type Material

Type deposition. Holotype and paratypes in Australian National Insect Collection, paratypes or type-compared vouchers in Australian Museum, Museum Victoria, Melbourne, Queensland Museum, South Australian Museum, WAMA, TMHA) and in The Natural History Museum, California Academy of Sciences, Museum of Comparative Zoology, Musee d'Histoire Naturelle Genève.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.



General features as illustrated and in key couplets 1–4. The brassy cephalic pubescence is more diffuse and less evident than in Myrmecia banksi, and the middle and hind tibiae are consistently medium to dark brown, with the tarsi a shade lighter. Local identification remains straightforward as long as M. imaii remains the only species of the Myrmecia pilosula complex found in WA.

(Holotype, smallest paratype, largest paratype (mm): TL = ca 13.40, 12.00, 14.46; HW = 2.68, 2.32, 2.79; HL = 2.49, 2.16, 2.59; CI = 107, 107, 107; EL = 0.99, 0.88, 1.01; OI = 37, 38, 36; SL = 2.15, 1.93, 2.17; SI = 80, 83, 77; PW = 1.63, 1.43, 1.70; WL = 3.90, 3.33, 4.06; PetW = 1.07, 0.85, 1.08; PpetW = 1.64, 1.27, 1.65.


  • 2n = 8, karyotype = 8A (Australia) (Imai et al., 1994; Hirai et al., 1994; Hirai et al., 1996) (Complex pilosula).
  • 2n = 6 (Australia) (Imai et al., 1994) (Complex pilosula).

Taylor (2015): The basic karyotype, 2K=6A +2Am(2n=8) differs strongly from those of other species reviewed above. Two independent AM inversions on chromosomes 1 and 2 were described in detail by Imai, Taylor et al. (1994: 146, Fig 5c–g). Complicated chromosome polymorphisms accompanying chromosome number reduction (2n=8 >7 > 6) by AM inversion, centric fission and centric fusion were also observed between chromosomes 1L and 4 and between chromosomes IS and 3. Despite this complexity the authors considered all examined specimens to be conspecific.


Named for Hirotami T. Imai celebrating long friendship; to commend his leadership of the JACP project, his distinguished research on the karyology of Myrmecia species and other ants, his important “Minimum Interaction Hypothesis” for the evolution of chromosome numbers in animals and his productive stewardship of the Japanese Ant Database Group (2003).


References based on Global Ant Biodiversity Informatics

  • Taylor R. W. 2015. Ants with Attitude: Australian Jack-jumpers of the Myrmecia pilosulaspecies complex, with descriptions of four new species (Hymenoptera: Formicidae: Myrmeciinae). Zootaxa 3911(4): 493-520.