Strumigenys dyak

Identification
Bolton (2000) - 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.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia.

Nomenclature

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

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) [examined].