Apomyrma stygia

Apomyrma stygia
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Apomyrminae
Genus:	Apomyrma
Species:	A. stygia
Binomial name
	Apomyrma stygia; Brown, Gotwald & Levieux, 1971 Specimen Label

In the original description (Brown et. al 1970) the authors suggest this species lives an entirely subterranean existence, primarily inhabits tropical forests, and belongs to a guild of centipede feeding ants. It was also stated that "Apomyrma, like many other other subterranean predatory ponerines, moves deep (30 cm or more) into the soil during the dry season (October to April), but during the rainy season it comes up to within 10 cm of the surface."

Identification

In the field and with the naked eye resembles a small, slender, shining Amblyopone. Possesses a pedunculate petiole with no differentiated postpetiole. Helium attached low down on the anterior face of abdominal segment 3 (see figure in the Nomenclature section).

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 6.557986° to -23.43333333°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: AntMaps

Distribution based on Regional Taxon Lists

Afrotropical Region: Benin, Cameroun, Ivory Coast (type locality), Nigeria.

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.

Biology

As reported by Brown et al. (1970)

"The 4 nests of A. stygia were all found during April-June 1968. Nos. AA 315 NI and AA 318 NI (both May 1968) were taken in sandy alluvial soil of the gallery forest of the Bandama River. The soil surface in each case, while tree-shaded, was bare of herbage. AA 315 NI, a nest fragment of the large form consisting of 12 workers and a single dealate queen, was taken about 10 cm deep, and was found in the same meter quadrat as Amblyopone sp. near normandi. AA 318 NI, 15 workers and a dealate queen, was found about 15 cm beneath the surface and in the same meter quadrat as a colony of Xymmer muticus (as Amblyopone mutica).

The type nest (without code number) was taken 7 June 1968; it and AA a85 N8 came from unburned savanna with dark clayey "terre noire" soil bearing a cover of the grass Loudetia simplex growing about 1 m high. The nest contained about 75 workers, 6 alate and 15 dealate queens, ergatoids, and a a few pupae and pharate adults of queens, males and workers, plus a few larvae of different sizes.

The type nest was 15-20 cm in diameter and cm high, containing the brood, most of the adults, and cut-up remains of a geophilornorph centipede determined by M. Demange of the Muse Nationale d’Histoire Naturelle, Paris, as belonging to genus Schendylurus. This suggests that Apomyrma, like a larger new species of Amblyopone found at Lamto, is a specialist predator of geophilomorph chilopods. Of course, direct observations on feeding are needed.

The colony did not occupy more than a part of the cavity, and it seems likely that the workers merely touched up a pre-existing hollow of some sort. From the main chamber ran several passages in different directions. Their diameter (less than 3 mm), their position and lengths, as far as one could follow them, resembled the paths of vanished grass roots. After finding this nest, the soil was dug carefully for a meter around it and to a depth of 30 cm, but no more specimens were found.

AA285 NS, found 6 April 1968, consisted of about 32 workers and a dealate queen from a small pocket about 20 cm deep.

The occurrence of winged sexual adults and pupae in mid-June suggests that Apomyrma has a nuptial season in late June, a little later than that assumed for Amblyopone species at Lamto."

Castes

Worker

The type species description notes there are small and large form workers, with the variation being found between nests. The former are ~ 2 mm in total length while the latter are ~3 mm in total length and are generally more robust.

Ergatoid queens were found in the nest of the type series.

Images from AntWeb


Worker. Specimen code casent0101444. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by MNHN, Paris, France.


Worker. Specimen code casent0101469. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by MNHN, Paris, France.


Worker. Specimen code casent0103304. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by MNHN, Paris, France.


Worker. Specimen code casent0103306. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by MNHN, Paris, France.


Worker. Specimen code casent0000077. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by CAS, San Francisco, CA, USA.

Queen

Images from AntWeb


Queen (alate/dealate). Specimen code casent0101445. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by MNHN, Paris, France.


Queen (alate/dealate). Specimen code casent0103305. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by MNHN, Paris, France.


Queen (alate/dealate). Specimen code casent0007017. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by CAS, San Francisco, CA, USA.

Nomenclature

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

stygia. Apomyrma stygia Brown, Gotwald & Lévieux, 1971: 264, figs. 1-9, 2 pls. (w.q.m.) IVORY COAST.
- Type-material: holotype queen, paratype workers (number not stated), paratype queens (number not stated), 1 paratype male (pharate).
- Type-locality: holotype Ivory Coast: Lamto, (ca 50 km. S) Toumodi, 17.vi.1968 (J. Lévieux); paratypes with same data and also same data plus nests AA 285 N8, AA315 N1, AA318 N1, some dated 16.iv.1968.
- Type-depositories: MNHN (holotype); BMNH, MCZC, MHNG, MNHN, UCDC (paratypes).
- Wheeler, G.C. & Wheeler, J. 1971a: 276 (l.); Boudinot, 2015: 23 (m.).
- Status as species: Bolton, 1995b: 74; Boudinot, 2015: 24.
- Distribution: Benin, Cameroon, Central African Republic, Democratic Republic of Congo, Ghana, Ivory Coast, Nigeria, South Africa.

Description

Worker, small form, composite description - total length (TL) 2.0-2.2 mm, head length (HL) 0.46-0.50 mm, head width (HW) 0.32-0.34 mm, cephalic index (CI) 68-70, scape length 0.20-0.22mm, hind femur length 0.22-0.24 mm, length of trunk (WL) 0.59-0.69 mm, length of petiole with anterior and posterior peduncles 0.27-0.28 mm, length of petiolar node 0.20-0.21 mm, width of node 0.18-0.20 mm, length of postpetiole (first gastric segment) 1.16-0.19 mm, width of postpetiole 0.23-0.26 mm. Length of hairs about 0.01-0.04 mm, mostly 0.02-0.03 mm. Hairs mostly erect, many inclined at different angles. The distribution of superficially reticulate areas on the cervix and lower sides of pronotum, on coxae, on sides of propodeum around spiracle, and on anterior sides of petiolar node are shown well in the scanning electron micrographs (Plates. I, II). The SEM also shows the sunken, narrow mesonotum to be transversely striolate.

Worker, large torm (from nest AA 315 NI) - TL 3.0-3.1 mm, HL 0.62-0.65 ram, HW 0.47-0.50 mm (CI 76-77), scape L 0.29-0.30 mm, hind femur L 0.35-0.36 ram, WL 0.91-0.96 mm, petiole L 0.38-0.41 mm, petiolar node L 0.27-0.29 mm, petiolar node W 0.30-0.32 ram, postpetiole L 0.25 rnm, postpetiole W 0.42 mm.

Distinctly more robust than small form; head, truncus, petiolar node, postpetiole and rest of gaster all relatively wider. Color darker, medium ferruginous. Punctures on head a little more numerous and much more distinct, at least in part because of the darker ground color. Otherwise, the large form is very similar to the small form, and probably is no more than a size variant of the same species showing slight allometric tendencies.

Queen, alate small form (holotype), from nest of 17 June, 1968 - TL 3.0 mm, HL 0.57 mm, HW 0.43 mm, (CI 75), scape L 0.26 mm, hind femur L 0.32 mm, forewing L 1.95 mm, WL 0.95 mm, petiolar node L 0.27 mm, petiolar node W 0.30 mm, postpetiolar node L 0.19 mm, postpetiolar node W 0.26 mm, greatest diameter of compound eye 0.11 mm.

Queen, dealate small form, from nest AA 38 NI - TL 2.7 mm, HL 0.54 mm, HW 0.4 mm (CI 76), scape L 0.24 ram, hind femur L 0.30 mm, WL 0.94 mm, petiolar node L 0.24 mm, petiolar node W 0.27 mm, greatest diameter of compound eye 0.095 mm.

Ergatoid - Two specimens from the type nest are intermediate between winged queens and workers from this nest series in size, and wings or wing stumps are absent. The mesonotum is reduced to a subquadrate piece. Compound eyes are present but smaller than in winged queens; 3 ocelli are present.

Male, pharate adult: removed from cocoon, which is similar in size and color to the small-form worker cocoons with which it was mixed in type nest. Pupal skin partly removed by needle. Total length (TL) about 2.8 mm, HL about 0.4 mm, WL about 1.1 mm. The specimen is still pale, with compound eyes in the purple stage (greatest diameter 0.24 mm), and only the first faint flush of tannish pigmentation showing, mainly on truncal dorsum. Numerous fine brownish points probably indicate the presence of an abundant fine pilosity. Details of smaller mouthparts cannot be made out, since the parts are still soft and transparent, but the mandibles are vestigial, small and triangular, with rounded apices, separated by nearly the whole width of the labrum. Details of middle front of head also obscure, but from what can be seen, not much different from the worker here. Antennae 3-segmented, with very short scape., funicular segments varying from about as broad as long to longer than broad; apical segment longest. Truncus as in Fig. 9; wings not yet unfolded. Petiole short, much higher and broader than long, thick-squamiform, with a free steep, flat anterior face, but attached over nearly its entire posterior face to the next gastric segment (postpetiole). This petiole is an axially-compressed version of the usual amblyoponine pattern. Gaster not unusually long, tapering gradually toward apex; genitalia not distinct, and represented in Fig. 19 only as a rough approximation. The integument, as far as it is developed, seems relatively smooth and featureless overall, though, as mentioned above, the punctulation is apparently rather dense.

Pupae, worker, queen and male, enclosed in white cocoons, about 2.0 to 2.6 mm long in the small form and 3.-3.5 mm in the large form, with conspicuous black meconial spot at one end.

Type Material

The holotype and some paratypes are deposited in the Musee National d'Histoire Naturelle. Other paratypes are placed in the Museum of Comparative Zoology, the The Natural History Museum, the Musee d'Histoire Naturelle Genève, and elsewhere. The type nest and 3 additional samples all came from the vicinity of Lamto Field Station of the University of Abidjan, south-central Cote d'Ivoire. Lamto is off the main highway 50 km or so south of Toumodi, the nearest town of any size.

Boudinot (2015) - Apomyrma stygia Brown, Gotwald Jr. & Lévieux, 1971: 264, figs. 1–19 (worker, queen, male). CÔTE D’IVOIRE, Lagunes: Station d’Ecologie de LAMTO , near Toumodi, 6°13’N 5°02’W, 75–120 m elevation, 16 Apr. 1968 (J. Lévieux), University of California, Davis paratype worker CASENT0260454 examined. Original label reads: “IVORY COAST Lamto, Toumodi, 16.iv.68 J. Levieux”.

References

Bolton, B. 1995b. A new general catalogue of the ants of the world. Cambridge, Mass.: Harvard University Press, 504 pp. (page 74, catalogue)
Borowiec, M.L., Moreau, C.S., Rabeling, C. 2020. Ants: Phylogeny and Classification. In: C. Starr (ed.), Encyclopedia of Social Insects (doi:10.1007/978-3-319-90306-4_155-1).
Brown, W. L., Jr.; Gotwald, W. H., Jr.; Levieux, J. 1971 [1970]. A new genus of ponerine ants from West Africa (Hymenoptera: Formicidae) with ecological notes. Psyche (Camb.) 77: 259-275. doi:10.1155/1970/64703 (page 264, figs. 1-9 , 2 pls. worker, queen, male described)
Cantone S. 2018. Winged Ants, The queen. Dichotomous key to genera of winged female ants in the World. The Wings of Ants: morphological and systematic relationships (self-published).
Fernandez, F., Guerrero, R.J., Sánchez-Restrepo, A.F. 2021. Sistemática y diversidad de las hormigas neotropicales. Revista Colombiana de Entomología 47, 1–20 (doi:10.25100/socolen.v47i1.11082).
Richter, A., Boudinot, B.E., Hita Garcia, F., Billen, J., Economo, E.P., Beutel, R.G. 2023. Wonderfully weird: the head anatomy of the armadillo ant, Tatuidris tatusia (Hymenoptera: Formicidae: Agroecomyrmecinae), with evolutionary implications. Myrmecological News 33: 35-75 (doi:10.25849/MYRMECOL.NEWS_033:035).
Wheeler, G. C.; Wheeler, J. 1971a [1970]. The larva of Apomyrma (Hymenoptera: Formicidae). Psyche. 77: 276-279. (page 276, larva described)

References based on Global Ant Biodiversity Informatics

Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research 3: 5-16.
Kugler C. 1992. Stings of ants of the Leptanillinae (Hymenoptera: Formicidae). Psyche (Cambridge) 99: 103-115.
Levieux J., and T. Diomande. 1985. Evolution des peuplements de fourmis terricoles selon l'age de la végétation dans une foret de Cote d'Ivoire intacte ou soumise à l'action humaine. Insectes Sociaux 32(2): 128-139.
Lévieux J. 1972. Les fourmis de la savane de Lamto (Côte d'Ivoire): éléments de taxonomie. Bulletin de l'Institut Fondamental d'Afrique Noire. Série A. Sciences Naturelles 34: 611-654.
Medler J. T. 1980: Insects of Nigeria - Check list and bibliography. Mem. Amer. Ent. Inst. 30: i-vii, 1-919.
Yeo K., T. Delsinne, S. Komate, L. L. Alonso, D. Aidara, and C. Peeters. 2016. Diversity and distribution of ant assemblages above and below ground in a West African forest–savannah mosaic (Lamto, Cote d’Ivoire). Insectes Sociaux DOI 10.1007/s00040-016-0527-6
Yeo K., and A. Hormenyo. 2007. A Rapid Survey of Ants in Ajenjua Bepo and Mamang River Forest Reserves, Eastern Region of Ghana. Pp 27-29. In McCullough, J., P. Hoke, P. Naskrecki, and Y. Osei-Owusu (eds.). 2008. A Rapid Biological Assessment of the Ajenjua Bepo and Mamang River Forest Reserves, Ghana. RAP Bulletin of Biological Assessment 50. Conservation International, Arlington, VA, USA.