Strumigenys dyak

Strumigenys dyak
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Strumigenys
Species:	S. dyak
Binomial name
	Strumigenys dyak; Brown, 1959 Specimen Labels

Nothing is known about the biology of Strumigenys dyak.

Identification

Bolton (2000) - A member of the mjoebergi complex in the Strumigenys godeffroyi-group. In many ways this species is an oddity within the mjoebergi-complex and probably does not really fit here. However, for the present this is the best placement that can be achieved. As mentioned above the petiolar spongiform lobes of dyak are similar in extent to species of the godeffroyi-complex and much larger than any other mjoebergi-complex species. S. dyak is also the only terrestrial species of the seven grouped here and is the only one to have an unsculptured postpetiole disc.

S. dyak appears closely related to Strumigenys baal but the latter lacks long erect hairs on the basitarsi. Abraded specimens of dyak that have lost the long basitarsal hairs may be distinguished from baal as follows.

1 Extent of the lateral spongiform lobe of the petiole: in baal the anteriormost point of the lobe in profile is close to the midlength of the node, in dyak it is very close to or at the anterior face of the node.

2 Disc of postpetiole in dorsal view: in dyak only slightly broader than long, approximately straight-sided and with boundary between dorsum and side of sclerite marked by a longitudinal sharp angle or fine carina; in baal distinctly broader than long, roughly transversely elliptical and without a sharply angled or carinate longitudinal margin between dorsum and side of sclerite.

Keys including this Species

Key to Strumigenys of East Asia

Distribution

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo (type locality), Indonesia, Malaysia.

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.

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Castes

Nomenclature

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

dyak. Strumigenys dyak Brown, 1959g: 81 (w.) BORNEO. See also: Bolton, 2000: 800.

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

Description

Worker

Bolton (2000) - TL 2.7-2.9, HL 0.68-0.80, HW 0.48-0.55, CI 68-74, ML 0.31-0.37, MI 45-48, SL 0.42-0.49, SI 86-89, PW 0.28-0.33, AL 0.74-0.82 (6 measured).

Characters of mjoebergi-complex. Apicoscrobal hair short, stiff and simple, acute apically; 1-2 similar but shorter hairs project from dorsolateral margin of head posterior to this. With head in full-face view the ventrolateral margin not visible behind the level of the eye. Cephalic dorsum with 4 stiffly erect simple hairs close to the occipital margin; head without other erect hairs but with sparse short ground-pilosity (less than half length of erect hairs) that is straight, elevated and inclined anteriorly. Pronotal humeral hair fine and filiform, moderately long, straight or at most evenly shallowly curved, acute apically. Dorsum of pronotum and mesonotum each with a pair of erect simple slender hairs. Side of alitrunk reticulate-punctate but most of katepisternum smooth. Lateral spongiform lobe of petiole large; in profile lobe extends forward almost to the level of the anterior face of the node, in dorsal view the lobe on each side just about reaches the anterolateral corner of the node. Disc of postpetiole mostly or entirely smooth, at most some feeble sculpture near the lateral margins. Basigastral costulae shorter than disc of postpetiole. First gastral tergite with simple standing hairs.

Type Material

Bolton (2000) - Holotype worker, MALAYSIA: Sabah, “head Camp, N Borneo”, British North Borneo collecting tour (E. Mjoberg); paratype worker, MALAYSIA: Sabah, North Borneo, foot of Mt Murud (E. Mjoberg) (Museum of Comparative Zoology) [examined].

References

Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 800, figs. 439, 492 redescription of worker)
Brown, W. L., Jr. 1959g [1958]. The Indo-Australian species of the ant genus Strumigenys Fr. Smith: group of S. godeffroyi in Borneo. Psyche. 65:81-89. (page 81, worker described)

References based on Global Ant Biodiversity Informatics

Brown W. L., Jr. 1959. The Indo-Australian species of the ant genus Strumigenys Fr. Smith: group of S. godeffroyi in Borneo. Psyche (Camb.) 65: 81-89.
Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58