Strumigenys orchidensis

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Strumigenys orchidensis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. orchidensis
Binomial name
Strumigenys orchidensis
Lin & Wu, W.-J., 2001

Strumigenys orchidensis casent0911243 p 1 high.jpg

Strumigenys orchidensis casent0911243 d 1 high.jpg

Specimen Labels

The type material was collected from a nest found on Orchid Island, Taiwan. Nothing is known about the biology of Strumigenys orchidensis.


Lin & Wu (2001) - Closely related to Strumigenys formosensis by the (1) sickle-like mandibles with an extreme apex; and (2) anterior median margin border of the clypeus being deeply concave. However it is easily distinguished from the latter by the following characters: (1) smaller body size (TL < 2.6 mm in orchidensis, TL > 2.8 mm in formosensis); (2) different pilosity on the cranium (with numerous short, narrowly spatulate hairs in orchidensis, with sparse hairs in formosensis); (3) the preapical teeth of mandible spiniform in orchidensis and reduced in formosensis; and (4) the different sculpturing on the pronotum.

This species has not been assigned to a species group (Strumigenys species groups).


Known only from Orchid Island, Taiwan.

Distribution based on Regional Taxon Lists

Oriental Region: Taiwan (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


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.



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

  • orchidensis. Strumigenys orchidensis Lin & Wu, 2001: 162, figs. 11-18 (w.q.) TAIWAN.

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



Holotype. TL, 2.89 mm; HL, 0.83 mm; HW, 0.59 mm; SL, 0.54 mm; ML, 0.39 mm; FCD, 0.20 mm; PW, 0.37 mm; WL, 0.84 mm; CI, 71; MI, 47; SI, 91; FCI, 34; MSI, 44.

Paratypes. TL, 2.78-2.93 mm; HL, 0.80-0.85 mm; HW, 0.58-0.60 mm; SL, 0.53-0.55 mm; ML, 0.39-0.42 mm; FCD, 0.20-0.21 mm; PW, 0.35-0.38 mm; WL, 0.82-0.86 mm; CI, 71-73; MI, 46-49; SI, 88-91; FCI, 33-34; MSI, 43-47.

Head as in Fig., with microreticulate sculpturing, with abundant, short, narrowly spatulate hairs on cranium; in full face view, posterolateral corners of head with 3 pairs of long flagellate hairs. Mandibles sickle-like, slender in full face view; external and internal margins almost straight; preapical teeth of mandibles prominently spiniform; apical fork with 2 spiniform teeth and an intercalary denticle. Anterior clypeal margin deeply concave medially. Antennae 6-segmented, in a ratio of 14.5:2.5: 1: 1: 4.5: 9.5 in length from base; scape microreticulate, with a row of narrowly spatulate hairs; 2nd segment 2 X as long as wide; 3rd and 4th segments each shorter than wide; 5th segment 3 X as long as wide; apical segment 6 X as long as wide. Eyes relatively large, 0.07 mm in maximum diameter, with about 15 ommatidia.

Dorsum of promesonotum with microreticulate sculpturing; pairs of long flagellate hairs and erect hairs present. Mesopleuron and metapleuron smooth and shiny on most parts. Metanotum with microreticulate sculpturing. Propodeal teeth acute and well developed; propodeal lamellae weakly developed.

Petiole with microreticulate sculpturing, with long flagellate hairs; peduncle long; dorsal margin of node convex in profile. Spongiform appendages of pedicelled segments well developed.

First gastral tergite smooth and shiny, with numerous, long flagellate hairs.

Body brownish yellow.


Paratype. TL, 2.80 mm; HL, 0.72 mm; HW, 0.56 mm; SL, 0.44 mm; ML, 0.34 mm; FCD, 0.19 mm; PW, 0.36 mm; WL, 0.74 mm; CI, 78; MI, 47; SI, 79; FCI, 34; MSI, 47.

General shape of head and alitrunk as shown in Figs. Head and antennal scape with microreticulate sculpturing. Head with narrowly spatulate hairs on cranium; in full face view, posterolateral corners of head with 3 pairs of long flagellate hairs. Compound eyes large. Ocelli relatively large, each with blackened callus.

Alitrunk in profile more even dorsally, arching from anteriormost of mesonotum to posteriormost of metanotum. Propodeal teeth acute and well developed; propodeal lamellae weakly developed. Dorsum of alitrunk with numerous short erect hairs. Long flagellate hairs present on dorsal of alitrunk, petiole, postpetiole, and 1st gastral tergite.

Body brownish yellow.

Type Material

Holotype, worker, Taiwan: Orchid Island, Taitung County, 10-ix-1997 (C. C. Lin) (Type depository: National Taiwan University).

Paratypes. One queen, 16 workers, Taiwan: Orchid Island, Taitung County, 10-ix-1997 (C. C. Lin), from the same nest as the holotype; 49 workers, Orchid island, Taitung County, 10-ix-1997 (C. C. Lin) (Type depository: National Taiwan University; National Museum of Natural Science, Taiwan; Taiwan Agricultural Research Institute).


Named after Orchid Island, the type locality of this new species.