Strumigenys ekasura

Strumigenys ekasura
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Strumigenys
Species:	S. ekasura
Binomial name
Strumigenys ekasura Bolton, 2000 Specimen Labels

Collected from numerous forest habitats, primarily via litter sampling.

Identification

Bolton (2000) – A member of the smythiesii complex in the Strumigenys godeffroyi-group. See notes under Strumigenys lichiaensis.

Sarnat and Economo (2012) - Strumigenys ekasura is part of the smythiesii complex, and is characterized by abundant freestranding flagellate pilosity, a sculptured postpetiolar disc, and conspicuous basigastral pilosity. The species is most similar to Strumigenys chernovi, from which it can be separated by the single laterally projecting fine hairs on each upper scrobe margin and lack of propodeal lamellae. See the identification section under S. chernovi for additional characters to separate it from its Fijian relatives.

Keys including this Species

• Key to Strumigenys of East Asia

Distribution

Fiji. Sarnat and Economo (2012) - widespread, recorded from most of the major islands with the exception of Taveuni and Ovalau.

Latitudinal Distribution Pattern

Latitudinal Range: -16.48° to -19.0775°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Indo-Australian Region: Fiji (type locality).

Distribution based on AntMaps

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.

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.

Biology

Explore Overview of Strumigenys biology  Strumigenys were once thought to be rare. The development and increased use of litter sampling methods has led to the discovery of a tremendous diversity of species. Many species are specialized predators (e.g. see Strumigenys membranifera and Strumigenys louisianae). Collembola (springtails) and other tiny soil arthropods are typically favored prey. Species with long linear mandibles employ trap-jaws to sieze their stalked prey (see Dacetine trap-jaws). Larvae feed directly on insect prey brought to them by workers. Trophallaxis is rarely practiced. Most species live in the soil, leaf litter, decaying wood or opportunistically move into inhabitable cavities on or under the soil. Colonies are small, typically less than 100 individuals but in some species many hundreds. Moist warm habitats and micro-habitats are preferred. A few better known tramp and otherwise widely ranging species tolerate drier conditions. Foraging is often in the leaf litter and humus. Workers of many species rarely venture above ground or into exposed, open areas. Individuals are typically small, slow moving and cryptic in coloration. When disturbed individuals freeze and remain motionless. Males are not known for a large majority of species. ‎

Castes

Strumigenys  X-ray micro-CT scan 3D model of Strumigenys ekasura (worker) prepared by the Economo lab at OIST.

See on Sketchfab. See list of 3D images.

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• ekasura. Strumigenys ekasura Bolton, 2000: 807 (w.) FIJI IS.

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

Description

Worker

Holotype. TL 2.3, HL 0.60, HW 0.42, CI 70, ML 0.22, MI 37, SL 0.35, SI 83, PW 0.27, AL 0.62. Characters of smythiesii-complex. Preapical tooth of mandible shorter than maximum width of mandible, its length about equal to width of mandible at point where it arises. Apicoscrobal hair flagellate. Upper scrobe margin anterior to apicoscrobal hair with long fine simple ground-pilosity. Cephalic dorsum finely minutely reticulate-rugulose, spaces between rugular meshes reticulate-punctate. Ground-pilosity of cephalic dorsum simple; 1-2 pairs of longer, anteriorly curved fine standing hairs at the occipital margin but without such hairs anterior to this, only the elevated ground-pilosity present. Pronotal humeral hair flagellate. Promesonotal dorsum with long curved ground-pilosity; in addition apparently with 1 pair of erect flagellate hairs on pronotum and 2-3 pairs on mesonotum. Promesonotal dorsum punctate to reticulate-punctate; propodeal dorsum with faint superficial sculpture only, more shining than promesonotum but not glassy smooth; propodeal declivity smooth. Side of pronotum mostly smooth; mesopleuron, metapleuron and side of propodeum smooth and highly polished. Propodeal tooth short, narrowly triangular, subtended by a narrow cuticular carina whose posterior (free) margin is concave. Dorsal surface of hind femur with 2 erect fine sub flagellate hairs; ventral surface with 3-4 similar hairs. One or two long erect sub flagellate hairs also present on dorsal (outer) surface of hind tibia. With petiole in profile the dorsum of the node much longer than its short oblique anterior face; lateral spongiform lobe small, restricted to posterior margin of node. Dorsum of petiole node weakly punctate; disc of postpetiole finely and densely longitudinally costulate-striolate, spaces between costulae finely shagreenate. Ventral lobe of postpetiole spongiform, not membranous and blister-like. First gastral tergite with erect flagellate hairs and long ground-pilosity. Basigastral costulae dense, slightly longer than disc of postpetiole but not extending half the length of the tergite; spaces between costulae superficially shagreenate.

Type Material

Holotype worker, Fiji Is: Vanua Levu, Kontiki, 19 km. E of Savusavu, 18.vii.1987, QM Berlesate No. 782, 16.48'S, 179.26 ' E, 20 m., secondary rainforest, sieved litter (G. Monteith) (Australian National Insect Collection).

• Holotype, worker, Kontiki, 19km E Savusavu, Vanua Levu, Fiji, Monteith,G., ANIC32-017722, Australian National Insect Collection.

References

• Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 807, worker described)
• Liu, C., Sarnat, E.M., Friedman, N.R., Hita Garcia, F., Darwell, C., Booher, D., Kubota, Y., Mikheyev, A.S., Economo, E.P. 2020. Colonize, radiate, decline: Unraveling the dynamics of island community assembly with Fijian trap‐jaw ants. Evolution 74, 1082–1097 (doi:10.1111/EVO.13983).
• Sarnat, E. M. and Economo, E. P. 2012. The ants of Fiji. University of California Publications in Entomology. 132:1-384.
• Sarnat, E.M., Hita-Garcia, F., Dudley, K., Liu, C., Fischer, G., Economo, E.P. 2019. Ready species one: Exploring the use of augmented reality to enhance systematic biology with a revision of Fijian Strumigenys (Hymenoptera: Formicidae). Insect Systematics and Diversity 3(6): 6; 1–43 (doi:10.1093/isd/ixz005).
• Tang, K. L., Guénard, B. 2023. Further additions to the knowledge of Strumigenys (Formicidae: Myrmicinae) within South East Asia, with the descriptions of 20 new species. European Journal of Taxonomy 907, 1–144 (doi:10.5852/ejt.2023.907.2327).

References based on Global Ant Biodiversity Informatics

• Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
• Sarnat Eli M. 2009. The Ants [Hymenoptera: Formicdiae] of Fiji: Systematics, Biogeography and Conservation of an Island Arc Fauna. 80-252
• Ward, Darren F. and James K. Wetterer. 2006. Checklist of the Ants of Fiji. Fiji Arthropods III 85: 23-47.