Indomyrma dasypyx

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Indomyrma dasypyx
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Indomyrma
Species: I. dasypyx
Binomial name
Indomyrma dasypyx
Brown, 1986

Indomyrma dasypyx casent0101964 profile 1.jpg

Indomyrma dasypyx casent0101964 dorsal 1.jpg

Specimen Label

Known only from a few collections, the types were fortunately collected as whole colonies. These colonies were placed in artificial nests, observed over time, and details of their behavior published as part of the species description (see biology section below).

Photo Gallery

  • Indomyrma dasypyx colony found in the Western Ghats, Kerala, India. Photo by Kalesh Sadasivan.

Identification

Zryanin (2012) - Indomyrma dasypyx can be distinguished from the only other species in the genus, Indomyrma dasypyx, by the number of ommatidia in worker, 2-3 in latter and 8-10 in the former. In worker and queen I. bellae distinguished from those of I. dasypyx in absence of subacute humeral angles, shape of petiolar node with rounded anterior edge, strong development of torose sculpture on head, alitrunk, petiole and postpetiole, foveolate or punctate sculpture at base of gaster and different character of pilosity (reduction of longer erect and suberect hairs).

Distribution

Distribution based on Regional Taxon Lists

Oriental Region: India (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Brown (1986):

Colonies were collected from from rotten logs in semideciduous forest.

Colonies from Kerala were estimated to contain between 100 and 500 workers plus copious brood in all stages of development. At the time of collection, all Kerala (April) nests contained some sexual brood, both males and queens together. Two colonies, M-238 and M-190, were kept alive for observation and rearing (Crozier's slide notation AABW-1 refers to nest M-238), and these were still eclosing a few winged forms in mid-May 1969 in a plaster-bottomed observation nest in the laboratory. The prepupal and male pupal tissue preparations for karyotyping were made during this period by Dr. Ross Crozier and myself, using his acetic acid, air-drying method (modified slightly; see Imai et al. 1977).

In the artificial nests, the ants were rather sluggish, and many entered into a death-feigning “pupal” pose upon the slightest physical disturbance. The workers and nest queens usually clustered thickly on the single, compact brood pile, virtually hiding it from view, in the manner of Myrmecina and some other small myrmicines, but in their natural nests in the field in India, the ants were found to be somewhat more dispersed in several definite chambers within good-sized pieces of rotten wood.

Within the artificial nest, Indomyrma workers accepted freshly killed, dismembered, housefly and scarabaeid beetle larvae, and live but disabled adult chironomids and mosquitoes, and fed them to at least the larger ant larvae directly. No ants were attracted to small droplets of diluted honey placed on tiny squares of waxpaper in one artificial nest, but these trials were very limited, and should not be taken as conclusive that the ants always ignore sweet substances. One peculiar habit, already alluded to in the descriptive section above (see male description, Indomyrma), is the worker transport of callow and fully pigmented adult males by means of the “antennal handles.” The peculiarly deformed male antennae (Figs. 13, 14) together form a curved, sublyriform handle or rack extending from the head forward. These are grasped in the worker mandibles, whereupon the transported male folds up his legs and remains motionless while he is being carried backwards, his rigid body often slanting upwards, to the new place where he will be set down. The worker mandibles appear to close upon that part of the male antennae where the most conspicuous modification (constriction) occurs (Fig. 14).

The four Kerala colonies observed first-hand appeared to be monogynous, that is, with only one dealate, deeply pigmented queen in each nest, but of course other functional queens may have escaped observation or capture during the confusion of collection.

Morphology

Malpighian tubules 5 in all castes, long, not cryptonephric (sample N = 1 queen, 4 males, 2 workers).

Genetics

Karyotype haploid number is 12 metacentric chromosomes, counted from 11 spreads from male pupal testes (Fig. 19), 15 spreads form prepupal brain of another male (Fig. 20) and two diploid spreads from the brain of a queen prepupa (Fig. 21 ), all from the cultured Peria Reserve (M-237) colony (see main biology section above). The slides were made by Dr. Ross Crozier and myself, and were stained, read and photographed by myself later.

Castes

Worker

Queen

Male

Nomenclature

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

  • dasypyx. Indomyrma dasypyx Brown, 1986: 46, figs. 1-21 (w.q.m.) INDIA.

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

Description

Worker

Holotype: TL 3.4, HL 0.80, HW 0.67 (CI 84), ML 0.21 (MI 26), SL 0.56 (SI 84), EL 0.05, WL 0.97, hind femur L 0.65, hind tibiaL 0.50 mm. Paratypes: TL 3.3-3.6, HL 0.70-0.83, HW 0.58-0.72 (CI 83-87), ML 0.18-0.22 (MI 26-27), SL 0.49-0.57 (SI 85-79), EL 0.03-0.05, WL 0.86-1.00 mm.

Habitus, sculpture and pilosity are for the most part represented well in figs. 1-3, 6 and 9, plus the generic characterization. (Indomyrma)

Queen

Paratypes (alate and dealate): TL 3.8-4.0, HL 0.76-0.80, HW 0.66-0.70 (CI 87-88), ML 0.23 (MI 29-30), SL 0.55-0.56 (SI 80-83), EL 0.19-0.21, WL 1.10-1.12, forewing L 3.2-3.4 mm.

Aside from the more robust stature and usual full-queen differences from the workers (Figs. 4, 7, 10), the queen has slightly more distinct interfoveolar, longitudinal costae on the middorsal head, and some also on the mesonotum. Suberect hairs more numerous, especially on pterothoracic notum and gastric tergum. Color of fully pigmented individuals dark brownish red, darker on dorsum of head and alitrunk, where it is mahogany approaching black. Appendages yellowish brown.

Male

Paratypes: HW (without eyes) 0.47-0.51 mm in 8 specimens measured.

One representative specimen had TL 3.1, HL 0.57, HW 0.50, ML 0.16, SL 0.30, EL 0.26, WL 0.98, forewing L 2.8 mm.

Type Material

Types: Holotype worker, from nest no. M-242 (see below) deposited with some paratypes in the Museum of Comparative Zoology at Harvard University, Cambridge, Massachusetts 02138, USA. Additional paratypes (all adult castes) in British Museum (Natural History), London; Cornell University Insect Collection, Ithaca; Australian National Insect Collection, Canberra; Zoological Survey of India, Calcutta, and California Academy of Sciences, San Francisco.

Localities, all in peninsular India: KERALA State (Western Ghats), Cannanore District, Peria Forest Reserve, nests all in rotten logs in disturbed semideciduous forest at about 900 m elevation; M-242, M-237, M-238, 4-5 April1969, A.B. Soans and W.L. Brown, Jr. leg. Kottiyoor in Wynaad Taluk, rotten wood in evergreen forest at about 650 m, M-190, 7 April 1969, Soans and Brown leg. MYSORE State: 8 mi. (13 km) NE of Mercara, 1000 m, 22 Feb. 1962, E.S. Ross and D. Q. Cavagnaro leg.

References