Acropyga hirsutula

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

Acropyga hirsutula casent0249921 p 1 high.jpg

Acropyga hirsutula casent0249921 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.

LaPolla (2004) - The specimens from Peru are alates (males and queens) marked as being collected at lights. A nest in Equador was discovered under a rock along the bank of a river. The nest was large, with many tunnels and indistinct chambers, and was found to contain multiple dealate queens (Alex Wild, pers. comm.).

Identification

LaPolla (2004) - Worker: 11 segmented antennae; head longer than broad; mandible with at least 4 teeth; when with 4 teeth a short diastema separates basal tooth from others; when with 5 teeth, 4th tooth smaller than others; clypeus with a dense covering of hairs. Queen: as in worker. Male: 12 segmented; parameres rectangular shaped covered in a thick layer of erect hairs; penis valve with prominent, roughly square, ventral extension, forming a long curve from tip. Compare with Acropyga decedens and Acropyga dubitata.

The queens of this species are quite distinctive, with an extremely hairy clypeus and gaster. The males are also of great interest since their penis valves have a dorsal notch, only observed in one other species, Acropyga dubitata, from Hispaniola. The elongated, square-shaped ventral extension and heavy contours of the surface of the penis valves also suggest a close relationship with A. dubitata.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Ecuador, Peru (type locality).

Check distribution from AntMaps.

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Acropyga hirsutula for further details

Biology

Little is known about Acropyga hirsutula. 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.

  • hirsutula. Acropyga hirsutula LaPolla, 2004a: 52, figs. 38, 45 (q.m.) PERU.

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: 2.04-2.07; HW: 0.477-0.482; HL: 0.523-0.543; SL: 0.381-0.41; ML: 0.553-0.568; CI: 88.77-91.20; SI: 79.05-85.95.

Head: yellow; posterior margin slightly concave; covered in a thick layer of appressed hairs, with scattered suberect to erect hairs; 11 segmented, incrassate antennae; scape surpasses posterior margin by about the length of the pedicel; clypeus broad, convex medially, covered in a thick layer of appressed to erect hairs; mandible with 4-5 teeth; basal tooth offset by a diastema when with only 4 teeth, or with a smaller tooth present when with 5 teeth; gap exists between anterior clypeal margin and inner mandibular margin. Mesosoma: yellow, in lateral view pronotum rises steeply toward mesonotum; posteriorly pronotum with many erect hairs; mesonotum covered in a thick layer of appressed hairs, with many scattered erect hairs; mesonotum higher than propodeum; metanotal area distinct, with one or two sulci present; propodeum rounded with thick layer of appressed hairs, and scattered erect hairs; declivity steep. Gaster: petiole thick and erect; gaster yellow; covered in a thick layer of appressed hairs, with many erect hairs throughout.

Queen

(n=2): TL: 2.89-2.96; HW: 0.609-0.629; HL: 0.653-0.655; SL: 0.588-0.591; ML: 0.929-1.21; CI: 93-96.3; SI: 94-98.1. As in worker with modifications expected for caste.

Male

(n=2): TL: 2.08-2.16; HW: 0.414-0.456; HL: 0.45-0.487; SL: 0.406-0.412; ML: 0.714-0.779; GL: 0.816-1; CI: 92-93.93; SI: 90.4-98.1.

Head: brown, slightly paler on clypeus, mandible and antennae, darker at apex around 3 prominent ocelli; head longer than broad; covered in layer of thick appressed hairs, becoming suberect to erect along posterior margin; posterior margin entire; eyes large, breaking outline of head when in full frontal view; 12 segmented, slightly incrassate antennae; apical segment about as long as preceding 2 segments; scape surpasses posterior margin by about the length of the first 2 funicular segments; clypeus narrow, convex medially, covered in a thick layer of appressed to erect hairs; mandible with 3 indistinct teeth, the basal tooth slightly offset from masticatory margin. Mesosoma: brownish-yellow; pronotum short and collar-like, overarched by rounded mesonotum; pronotum covered in thick layer of appressed to erect hairs; mesonotum broad and flat, covered in thick layer of appressed to erect hairs; propodeum gently rounded; declivity not distinct from propodeum. Gaster: petiole thick and erect; gaster brownish-yellow; covered in thick layer of appressed hairs, with scattered erect hairs throughout. Genitalia: in lateral view parameres roughly rectangular, covered in thick layer of erect hairs; cuspi cylindrical, with short, peg-like teeth at apices; digiti roughly anvil-shaped apically, with ventral portion elongated to a sharp point; cuspi and digiti meet dorsally, forming a roughly oval-shaped space between them; penis valves in dorsal view not reaching caudal ends of parameres; in ventral view, penis valve ventral extension prominent.

Type Material

Holotype queen, PERU: Tingo Maria and vicinity (W.L. Brown and W. Sherbrooke) (MCZC); 1 paratype queen, 5 paratype males, same locality as holotype (MCZC); 4 paratype workers, 4 paratype males, ECUADOR: Napo: Carlos 1. Arosemena Tola, 500 m, 010 09' S, 0770 53' W (A.L. Wild) (#AW2298) (JSLC) (MCZC). The holotype is labeled JSL TYPE # 104.

Etymology

The specific epithet hirsutula is Latin for hairy or bristly, in reference to the abundant pilosity of this species, especially on the clypeus and gaster.

References