Acropyga inezae

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Acropyga inezae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Plagiolepidini
Genus: Acropyga
Species: A. inezae
Binomial name
Acropyga inezae
Forel, 1912

Acropyga inezae casent0906269 p 1 high.jpg

Acropyga inezae casent0906269 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of this species.

Identification

LaPolla (2004): Worker: 11 segmented antennae; mandible with 4 teeth, basal tooth enlarged and rectangular, apically truncated. Queen: As in worker with modifications expected for caste. Male: 12 segmented antennae; 4 mandibular teeth; parameres thin; digiti with truncated apices; cuspi meet digiti about half way along length of digiti. Compare with Acropyga butteli and Acropyga nipponensis.

This species can be recognized from other species in the butteli species-group since it only has 4 mandibular teeth as opposed to 5. The 3rd tooth from apical has a distinctive appearance that can be diagnostic; this tooth in some specimens examined looks similar in appearance to the truncated basal tooth. It seems likely that the unique shape of the 3rd tooth resulted from the fusion of 2 formerly separate teeth, but what is not clear is if A. inezae ever has 5 teeth, with the 3rd tooth being separated into 2 distinct teeth. The specimen sample available for study was small, so it cannot be completely discounted that 5 teeth may be possible. Future analysis of the butteli species-group should take the possibility of variation in teeth number into account for this species.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Indonesia (type locality), Malaysia.

Known only from Sumatra and Borneo.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Little is known about Acropyga inezae. Until further studies reveal more about this species we can infer that its natural history and biology should be similar to other Acropyga. LaPolla published a worldwide revision of the Acropyga in 2004 and the following synopsis is based on this excellent treatment of the genus.

In overall appearance Acropyga are small, robust, yellowish ants possessing a thin, easily collapsible cuticle. The species generally appear rather similar to each other morphologically. In some species workers and queens display an unusual range of phenotypic variation. Antennal segment number, for example, can vary within and between species. Even a single specimen may posses antennae with a different number of antennal segments and workers in numerous species possess one more antennal segment than conspecific males.

The small eyes, reduced antennae segmentation, lightly pigmented cuticle, and hairs covering the cuticle of Acropyga species are suggestive of a completely subterranean existence. Species also display photophobic behavior (Weber, 1944; LaPolla et al., 2002). Acropyga can survive in a wide range of habitats, from deserts to rainforests, though they do not seem able to survive in regions where temperatures below freezing persist for several months at a time. Some species, such as Acropyga pallida and Acropyga silvestrii for example, are found within a very wide range of habitats. Undoubtedly, the Acropyga lifestyle of existing below the surface buffers them against extremes of the outside environment.

Acropyga nests are found in leaf litter, under stones, in rotten wood (lying on or near the soil surface) and in the soil. Observations of nests of various species show the nests are large, consisting of at least several thousand individuals. The nest structure is diffuse with apparently no central nesting location (LaPolla et al., 2002). Tunnels and indistinct chambers stretch out over large areas through the nesting medium. Polygyny has been suggested for several species. The origins of polygyny remains uncertain, but two routes are suggested based on field observations. Biinzli (1935) found both the occurrence of pleometrosis (founding of a colony by multiple queens) and the acquisition of young queens by established colonies in Acropyga exsanguis.

All Acropyga are thought to be hypogaeic (living entirely underground), surviving primarily by "tending" mealybugs (Hemiptera: Pseudococcidae) on underground roots for their exudate (sometimes referred to as "honeydew") (Weber, 1944; Williams, 1998). This mutually beneficial relationship is called trophobiosis (Holldobler and Wilson, 1990).

Acropyga species are all believed to be obligate coccidophiles (dependent on their tended mealybugs for survival). The strength of this trophophitic relationship is clarified by a number of observations. Queens of eleven species have been observed emerging from their nests prior to their mating flight with a mealybug held in their mandibles (Biinzli, 1935; Wheeler, 1935b; Brown, 1945; Eberhard, 1978; Prins, 1982; Buschinger et al., 1987; Williams, 1998; Johnson et al., 2001). The mealybug that each queen carries presumably serves as a "seed individual" from which a new generation of mealybugs will be started in the newly founded ant colony (Weber, 1944; Williams, 1998). This behavior is called trophophoresy (LaPolla et al. 2002) with queens exhibiting this behavior said to be trophophoretic. The mealybugs utilized by Acropyga belong to the subfamily Rhizoecinae, and it is likely that the mealybugs are not able to survive independently of the ants (Williams, 1998). LaPolla et al. (2002) observed that Acropyga epedana keeps mealybugs with their brood. When a nest in captivity was starved, workers refused a variety of food items presented to them, suggestiving that the ants are completely dependent on the mealybugs as a food source. Fossil evidence suggests that the trophobiotic behavior ofAcropyga ants is an ancient one. Johnson et al. (2001) reported that Acropyga queens were discovered in Dominican amber, either holding a mealybug or with a mealybug nearby in the amber matrix. The amber was dated to the Miocene and is at least 15-20 million years old.

Castes

Nomenclature

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

  • inezae. Acropyga (Atopodon) inezae Forel, 1912m: 772 (w.) INDONESIA (Sumatra). Karavaiev, 1933a: 314 (q.m.). [Also described as new by Forel, 1913k: 102.] See also: LaPolla, 2004a: 38.

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

Description

Worker

LaPolla (2004) - (n=6): TL: 1.48-1.7; HW: 0.403-0.432; HL: 0.485-0.522; SL: 0.313-0.341; ML: 0.31-0.449; GL: 0.612-0.811; CI: 79.01-86.21; SI: 73.30-81.38.

Head: yellow; covered in layer of appressed hairs; head longer than broad; posterior margin entire; 11 segmented, incrassate antennae; scapes fail to reach posterior margin by about length of 1st three funicular segments; clypeus broad, convex medially; median portion clypeal anterior margin with rounded bulge giving clypeus a beak-like appearance; mandible broad with 4 teeth; basal tooth enlarged and rectangular, apically truncated; 3rd tooth without well-defined cusp and larger than 1 st and 2nd teeth, occasionally forming a truncated tooth similar to basal tooth; basal tooth offset from other teeth; anterior clypeal margin and inner mandibular margin nearly parallel. Mesosoma: yellow; pronotum covered with appressed hairs, long, erect hairs placed posteriorly; mesonotum flat, at about same height as propodeum; dorsum covered in appressed hairs; metanotal area indistinct; propodeum flat rounded into steep declivity. Gaster: yellow, covered in a thick layer of appressed hairs with scattered erect hairs throughout.

Queen

LaPolla (2004) - (n=2): TL: 2.74-2.92; HW: 0.52-0.526; HL: 0.571-0.583; SL: 0.412-0.439; ML:0.819-0.848; GL: 1.34-1.5; CI: 89.19-92. 12; SI: 60.22-72.78. As in worker caste with modifications expected for caste and with the following differences: scape slightly longer in queens, occasionally reaching posterior margin to slightly failing to reach posterior margin; color yellow to brownish-yellow.

Male

LaPolla (2004) - (n=2): TL: 1.66-1.78; HW: 0.316-0.362; HL: 0.364-0.38; SL: 0.218-0.23; ML: 0.464-0.557; GL: 0.831-0.844; CI: 86.81-95.26; SI: 60.22-72.78.

Head: brownish-yellow, darker toward apex around three prominent ocelli; head slightly longer than broad; eyes large, breaking outline of head in full frontal view; 12 segmented antennae; scapes fail to reach. posterior margin by about length of pedicel; clypeus broad, slightly convex medially, with erect hairs scattered throughout; shape of anterior clypeal margin similar to that of worker caste, but median tooth less defined; mandible broad with 4 teeth, basal tooth enlarged and rectangular, apically truncated as in worker caste. Mesosoma: yellow; pronotum short and collar-like, overarched by mesonotum; mesonotum rounded anteriorly; dorsum flat with erect hairs scattered throughout, especially on scutellum; propodeum short; declivity steep. Gaster: yellow; covered in a layer of appressed hairs, with scattered erect hairs throughout. Genitalia: in lateral view, parameres thin, taper to rounded apices; hairs evenly distributed across dorsal surface of parameres; in dorsal view parameres give genitalia a roughly triangular appearance; cuspi short, bent toward digiti, with peg-like teeth at apex; digiti longer than cuspi and bent toward cuspi with truncated apex; peg-like teeth found at about mid-length of digiti where cuspi meet.

Type Material

LaPolla (2004) - Acropyga (Atopodon) inezae Forel, 1912c: 772 (w.). Syntype worker(s?), INDONESIA: Sumatra (Naturhistorisches Museum Basel) [examined). Lectotype is a worker labeled JSL TYPE # 113 is deposited at NHMB. Karavaiev, 1933: 314, description of queen and male.

References

  • Forel, A. 1912n. Descriptions provisoires de genres, sous-genres, et espèces de Formicides des Indes orientales. Rev. Suisse Zool. 20: 761-774 (page 772, worker described)
  • Forel, A. 1913l. Wissenschaftliche Ergebnisse einer Forschungsreise nach Ostindien ausgeführt im Auftrage der Kgl. Preuss. Akademie der Wissenschaften zu Berlin von H. v. Buttel-Reepen. II. Ameisen aus Sumatra, Java, Malacca und Ceylon. Gesammelt von Her (page 102, also described as new)
  • Karavaiev, V. 1933a [1932]. Ameisen aus dem Indo-Australischen Gebiet, VII. Konowia 11: 305-320 (page 314, queen, male described)
  • LaPolla, J.S. 2004a. Acropyga of the world. Contributions of the American Entomological Institute. 33(3):1-130. PDF (page 38, worker, queen, male described)