Acropyga stenotes

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Acropyga stenotes
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Plagiolepidini
Genus: Acropyga
Species: A. stenotes
Binomial name
Acropyga stenotes
LaPolla, 2004

Acropyga stenotes usnment00418290 p 1 high.jpg

Acropyga stenotes usnment00418290 d 1 high.jpg

Specimen Labels

Evolutionary Relationships
Acropyga



Acropyga ayanganna




Acropyga donisthorpei



Acropyga panamensis







Acropyga guianensis



Acropyga stenotes






Acropyga fuhrmanni



Acropyga smithii





Acropyga romeo




Acropyga hirsutula




Acropyga dubitata




Acropyga decedens, Acropyga goeldii



Acropyga epedana












Acropyga arnoldi



Acropyga silvestrii






Acropyga kinomurai



Acropyga lauta





Acropyga sauteri




Acropyga acutiventris




Acropyga myops




Acropyga butteli




Acropyga ambigua



Acropyga pallida










Based on Blaimer et al., 2016. Note only selected Acropyga species are included, and undescribed species are excluded.

Acropyga stenotes was collected from leaf litter samples in Dicymbe dominated forest along with Acropyga romeo, but otherwise nothing is known of its natural history.

Identification

LaPolla (2004) - Worker: 11 segmented antennae; head distinctly longer than broad, with head especially narrow-headed; mesosomal dorsum rounded in lateral view; mandible with 4 distinct teeth. Queen: unknown. Male: unknown. Compare with Acropyga smithii.

This species is fairly easy to recognize with its small size and distinctly narrow head. Its small size may initially make it difficult to distinguish from Acropyga smithii, but A. smithii possesses no more than 8 antennal segments, versus A. stenotes which has 11 segments. A. stenotes was among 3 new species of Acropyga discovered on an ant bioinventory of Mt. Ayanganna is western Guyana in the autumn of 2002. The rounded aspect of the mesosomal dorsum and long head suggests that this species is related to Acropyga guianensis. However, males of neither A. stenotes or A. guianensis are known, and therefore their relationship to each other remains unclear. Given the uncertain relationship of this species to other members of the genus it is unplaced in a species-group pending discovery of worker-associated males.

Key to New World Acropyga Workers

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Guyana (type locality).

This species is known only from its type locality at the base of Mt. Ayanganna in western Guyana.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Little is known about Acropyga stenotes. 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

Known only from the worker caste.

Nomenclature

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

  • stenotes. Acropyga stenotes LaPolla, 2004a: 79, fig. 33 (w.) GUYANA.

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

Description

Worker

(n=2): TL: 1.53; HW: 0.353-0.363; HL: 0.422-0.459; SL: 0.293- 0.31; ML: 0.414-0.436; GL: 0.635; CI: 76.91-86.02; SI: 80.72-87.82.

Head: yellow; head covered in a layer of short appressed hairs; head distinctly longer than broad, especially narrow-headed in full frontal view; posterior margin entire; posterolateral corners rounded; 11 segmented, incrassate antennae; scape fails to reach posterior margin by about length of first 2 funicular segments; clypeus narrow, slightly convex medially; clypeus with scattered erect hairs, longest ones along anterior clypeal margin; mandible narrow, with 4 distinct approximately similarly sized teeth; gap exists between anterior clypeal margin and inner mandibular margin. Mesosoma: yellow; in lateral view, pronotum with short shelf before rising sharply toward mesonotum; posteriorly pronotum with appressed to short erect hairs; mesosomal dorsum gently rounded from posterior pronotum through declivity; mesonotum flat with layer of appressed hairs; metanotal area indistinct; propodeum flat, slightly lower than mesonotum; declivity steep. Gaster: petiole thick and erect, reaching height of anterior portion of propodeal spiracle; gaster yellow; covered in a thick layer of appressed hairs, with scattered erect hairs throughout.

Type Material

Holotype worker, GUYANA: Camp on Potaro River at base of Mt. Ayanganna, N 05º 18.08, W 059º 54.67, elev. 695 m +/- 13 m, Dicymbe forest (J.S. LaPolla et al.) (UGBC); 9 paratype workers (MCZC) (USNM). The holotype is labeled JSL # 107.

Etymology

The specific epithet stenotes is Greek for narrowness, in reference to the narrow head of this species .

References