Ponera xenagos

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Ponera xenagos
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Ponera
Species: P. xenagos
Binomial name
Ponera xenagos
Wilson, 1957

Ponera xenagos P casent0249238.jpg

Ponera xenagos D casent0249238.jpg

Specimen Label

Relatively large for a Ponera, xenagos is only known from New Guinea.

Identification

Taylor (1967) - the largest known Ponera apart from Ponera alpha. Recognized by the combination of large size (head width 0.65-0.73 mm) with relatively broad head (cephalic index 84-90), vestigial medium clypeal tooth and relatively long scapes, which surpass the median occipital border by about 1/2 their maximum thickness. The eyes are small (4-5 indistinct facets) , and no antennal club is differentiated. Posterolateral propodeal angles not markedly raised, and node with more rounded contours than in alpha or selenophora, although it still maintains the same basic form with arched anterolateral and posterodorsal faces.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: New Guinea (type locality).

Distribution based on specimens

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The above specimen data are provided by AntWeb. Please see Ponera xenagos for further details

Biology

Wilson collected specimens from partial clearings beside trails in dense midmountain rain forest. He found one nest at each site, under loose bark on a rotting stump at Tumnang, and on the upper surface of a large rotting log at Ebaabang. Both nest sites were in partial clearings at the side of native trails running through dense midmountain rainforest. My Aiyura (Taylor) samples were taken in disturbed midmountain forest, nesting in rotting logs.

The general biology of species in the genus was summarized by Taylor (1967): Ponera are small ants that nest in rotting logs in forested areas or under stones in nonforested situations. In the tropical areas specimens are rarely encountered away from rain forest. In temperate areas, however, species may occur in relatively lightly forested areas. This appears to be the case with Ponera japonica, Ponera pennsylvanica and especially with Ponera coarctata. The Australian Ponera leae is essentially limited to rain forest in the northern parts of its range, but further south it may be found in dry, lightly forested areas.

Foraging is probably cryptobiotic, though some New Guinea species have been taken straying on the ground surface. Little information is available concerning feeding. However, most species are probably insectivorous. I have conducted feeding experiments with some of the New Guinea and Samoan species, including Ponera xenagos, Ponera elegantula, Ponera tenuis, Ponera incerta and Ponera woodwardi. These were unsuccessful with the larger species, except elegantula, which accepted moderately large (8-12 mm) campodeid and japygid Diplura. Tenuis and incerta accepted smaller (4-6 mm) campodeids, isotomid and sminthurid Collembola, and small newly hatched spiders (2 mm long). Negative feeding response was obtained with eggs and larvae of various ants, small crushed insects of various orders, and small myriapods. Stray workers were never observed carrying prey, and distinct middens of insect or other remains were not located near nests.

Colonies usually contain about 30 workers. Larvae and pupae are not segregated in most cases, but occasionally aggregations of pupae were observed. These may have included the total brood of the colonies involved. Larvae are attached to the floor or walls of the nest galleries by the glutinous abdominal tubercles described above, and the ants move them high up on the walls or ceilings of artificial nests, if they are flooded. Details of nuptial behavior of pennsylvanica were given by Wheeler (1900), and Haskins & Enzmann (1938). The flights appear to be of a pattern typical for ants, with the alates meeting in the air and mating there or on the ground. Colony foundation is non-claustral and independent in pennsylvanica (Kannowski 1959); judging from my observations this is typical for the genus.

Castes

Nomenclature

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

  • xenagos. Ponera xenagos Wilson, 1957b: 385 (w.) NEW GUINEA. See also: Taylor, 1967a: 43.

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

Description

Worker

Holotype. HW 0.67 mm, HL 0.77 mm, SL 0.59 mm, CI 87, SI 88, PW 0.52 mm, petiole height 0.53 mm, petiolar node length 0.27 mm, dorsal petiole width 0.42 mm. Very similar to P. selenophora Emery, differing by the following characters:

(1) Larger size.

(2) The three apical mandibular teeth occupy less than half the masticatory border, and distinct teeth are not developed on the basal half of the border as described for selenophora.

(3) The posterolateral margins of the propodeum are less pronounced; viewed from directly above they form an angle of only a little less than 90°.

(4) When viewed from directly above, the posterior margin of the petiolar node is almost perfectly straight, as opposed to the distinctly concave margin of selenophora.

(5) Pubescence is generally sparser. The anterior face of the petiolar node has pubescence only over its upper quarter, and there it is relatively sparse, whereas in selenophora it is abundant over the entire upper half.

Paratype variation. HW 0.65-0.68 mm, HL 0.75-0.80 mm, SL 0.57-0.60 mm, CI 86-90, SI 83-89, PW 0.52-0.54 mm, dorsal petiole width 0.40-0.44 mm.

Immature Forms

Taylor (1967) - Larvae from Aiyura have 3 pairs of dorsal abdominal glutinous tubercles, as usual in Indo-Australian Ponera; the worker pupae are enclosed in cocoons (other castes not available).

Type Material

N-E. NEW GUINEA: Tumnang, 1500 m. (type locality), April 14-15, 1955, holotype and eight paratype workers (Wilson, acc. no. 801); Ebabaang, 1300-1400 m., April 16-18, 1955, three paratype workers (Wilson, acc. no. 819). Both of the above localities are in the Mongi River Watershed of the Huon Peninsula. Museum of Comparative Zoology.

References

  • Taylor, R. W. 1967a. A monographic revision of the ant genus Ponera Latreille (Hymenoptera: Formicidae). Pac. Insects Monogr. 13: 1-112 (page 43, see also)
  • Wilson, E. O. 1957b. The tenuis and selenophora groups of the ant genus Ponera (Hymenoptera: Formicidae). Bull. Mus. Comp. Zool. 116: 355-386 (page 385, worker described)