Acropyga lauta

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Acropyga lauta
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Plagiolepidini
Genus: Acropyga
Species: A. lauta
Binomial name
Acropyga lauta
Mann, 1919

Acropyga lauta casent0171066 p 1 high.jpg

Acropyga lauta casent0171066 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.

Johnson et al. (2001) recorded this species as trophophoretic. It has been associated with the mealybugs Eumyrmoccus kolobangarae and E. kusiacus.

Identification

LaPolla (2004) - Worker: 8-9 segmented antennae; mandible with 4 teeth, basal tooth separated by a short diastema. Queen: as in worker with modifications expected for caste. Male: unknown. Compare with Acropyga sauteri.

The worker of this species is easily separated from Acropyga sauteri by the presence of 8-9 segmented antennae and the basal teeth offset by a diastema separating them from the other teeth. The large size of the species and four teeth on the mandible, coupled with the fact it possesses darker queens, has led to its provisional placement within the myops species-group. A. lauta has a similar mesosomal structure to Acropyga kinomurai and A. sauteri. Like A. kinomurai and A. sauteri, A. lauta also displays reduced mandibular dentition. Based on the dense covering of hairs on the mandibles, this species may be most closely related to A. kinomurai. However, A. lauta torulae are closely set, unlike other members of the myops species-group. Therefore, the exact placement of A. lauta awaits discovery of worker-associated males.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Solomon Islands (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Little is known about Acropyga lauta. 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.

  • lauta. Acropyga (Rhizomyrma) lauta Mann, 1919: 365 (w.q.) SOLOMON IS. See also: LaPolla, 2004a: 65.

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=8): TL: 1.94-2.34; HW: 0.51-0.579; HL: 0.49-0.556; SL: 0.356-0.427; ML: 0.541-0.647; GL: 0.89-1.14; CI: 99.03-108.17; SI: 68.07-78.24.

Head: yellow; head covered in thick layer of appressed hairs; head longer than broad; posterior margin entire; 8-9 segmented, incrassate antennae; scape fails to reach posterior margin by about length of pedicel; clypeus narrow, with many suberect to erect hairs on surface; clypeus convex medially; mandible typically with 4 distinct teeth, the 4th tooth from apical separated by a short diastema; smaller 5th tooth can sometimes form in the diastema region; inner mandibular margin nearly parallel to anterior clypea1 margin; dorsal surface of mandible very hairy (< 20 hairs). Mesosoma: yellow; in lateral view pronotum with short anterior shelf before rising steeply toward mesonotum; mesonotum covered in a dense layer of short suberect to erect hairs; longer hairs occasionally found posteriorly; mesonotum at same height as pronotum and propodeum; mesonotum dorsum flat, covered in a dense layer of short suberect to erect hairs; metanotal area distinctly pinched in laterally from mesonotum and propodeum giving it an "hour glass" appearance in dorsal view; propodeum dorsum flat, covered in a dense layer of short suberect to erect hairs; declivity steep. Gaster: petiole thick and erect, narrowing slightly toward apex, reaching height of bottom portion of propodeal spiracle; gaster yellow; covered in a dense layer of appressed hairs with scattered erect hairs throughout.

Queen

LaPolla (2004) - (n=2): TL: 2.82-3.36; HW: 0.547-0.56; HL: 0.528-0.54; SL: 0.422-0.44; ML: 0.946-0.988; GL: 1.31-1.87; CI: 101.3; SI: 75.36. As in worker with modifications expected for caste, and with the following differences: darker than worker (brownish-yellow in color).

Type Material

LaPolla (2004) - Acropyga (Rhizomyrma) lauta Mann, 1919: 365 (w.q.). 7 syntype workers, 1 syntype queen, SOLOMON ISLANDS: Auki, Malaita (W.M. Mann) (Museum of Comparative Zoology) [examined]; 12 syntype workers, 4 syntype queens, SOLOMON ISLANDS: Pamua (W.M. Mann) (National Museum of Natural History) [examined]. The designated lectotype is a worker labeled JSL TYPE # 127 and is deposited at MCZC.

References