Ponera adumbrans

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Ponera adumbrans
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Ponera
Species: P. adumbrans
Binomial name
Ponera adumbrans
Csősz & Fisher, 2023

Ponera adumbrans p F3 C.png

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Ponera adumbrans is known from a handful of collections made in the Seychelles. The holotype series was found on a ridge toward Mont Corgat, in forest sifted litter (leaf mold and rotten wood).

Identification

This species cannot be confused with other Malagasy Ponera species due to its dark brown color in contrast to the yellowish brown color of Ponera petila and Ponera swezeyi and its larger body size relative to the latter two species. Worldwide, this species most resembles the Indo-Australian Ponera clavicornis, but P. adumbrans clearly differs from its congener in shape, color, and size characteristics. The two species exhibit non-overlapping ranges of morphometric ratios: P. adumbrans has a shorter head (cephalic index, CI: 77 [75, 78]) than P. clavicornis (CI: 81–85, see Taylor, 1967), and the scape of P. adumbrans is longer (SI: 93 [90, 96]) than that of P. clavicornis (SI: 80–89, see Taylor, 1967).

Distribution

Known only from the Seychelles islands Silhouette and Mahé.

Latitudinal Distribution Pattern

Latitudinal Range: -4.4° to -4.4°.

 
North
Temperate 		North
Subtropical 		Tropical South
Subtropical 		South
Temperate
  • Source: Csősz et al., 2023

Distribution based on Regional Taxon Lists

Malagasy Region: Madagascar (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.
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Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.
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Biology

Explore-icon.png Explore Overview of Ponera biology 
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 Online Catalogue of the Ants of the World.

  • adumbrans. Ponera adumbrans Csősz & Fisher, in Csősz et al., 2023: 6, fig. 3A-C (w.) MADAGASCAR.

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

Description

Worker

Small species, absolute cephalic size (CS): 533 μm [518, 550]. Body color brown to black. Body concolorous, with antennae, funiculus, and legs lighter.

Head Small, Head width (CWb): 462 μm [447, 478]; and conspicuously longer than broad, Cephalic index (CI): 77 [75, 78]. Frontal lobe distance vs. absolute cephalic size (FRS/CS): 0.25 [0.24, 0.26]. Head dorsum coarsely punctate. Anterior clypeal margin with an inconspicuous median indentation or notch. Eyes absent, occasionally 1 to 3 facets are visible. Scape longer, Scape index (SI): 93 [90, 96]; when laid straight back from its insertion the apex falls near, but does not reach, the midpoint of the posterior margin in full-face view. Mandibles with 3 distinct apical teeth occupying half of the masticatory border.

Mesosoma Pronotal-mesonotal articulation present and developed across dorsum of mesosoma; always a strongly defined groove that conspicuously interrupts the surface. Metanotal groove absent. Dorsal surface of mesosoma coarsely punctate, dull. Lateral surface of pronotum finely punctate or areolate, dull. Mesopleural sculpture punctate to areolate, dull; metapleural sculpture longitudinally rugulose, partly shiny.

Petiole Petiolar node squamiform, large; petiole width vs.absolute cephalic size (PEW/CS): 0.55 [0.52, 0.58]; broader than long, (PEW/PEL): 1.34 [1.31, 1.41]; anterior face of node widely rounded, the sides usually very divergent posteriorly. Petiolar node in profile relatively high and moderately long, with a rather short and weakly convex dorsum. Dorsal region of petiole smooth to finely punctate, shiny. Anterior and posterior faces of node usually clearly convergent dorsally. Lateral surface of node meets the posterior surface in a rounded transition without a cuticular ridge or transverse carina. Subpetiolar process absent to moderately developed, if present, its apex forms a right angle.

Type Material

  • Holotype worker, Seychelles: CASENT0160838, collection code: BLF23554, Silhouette Island, on ridge toward Mont Corgat, [forest, sifted litter, leaf mold, rotten wood], -4.49537, 55.23946, alt. 445 m, B.L. Fisher et al., 2010.01.28, (3w, CASC).
  • Paratypes, six workers with the same label data as the holotype under CASENT codes: Seychelles: CASENT0160837, collection code: BLF23554, (1w, CASC); CASENT0160840, collection code: BLF23554, (1w, CASC); CASENT0159923, collection code: BLF23458, (1w, CASC); CASENT0159088, collection code: BLF23558, (1w, CASC); CASENT0159966, collection code: BLF23434, (1w, CASC); CASENT0158808, collection code: BLF23254, (1w, CASC); CASENT0159375, collection code: BLF24028 (1w, CASC).

Etymology

The specific name "adumbrans" is a Latin singular present active participle in the nominative case that means “obscuring or silhouetting.” It refers to the obscure origin of this species in the Malagasy region and the type locality, Silhouette Island.

References

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