Strumigenys signeae

Known from litter samples collected in rainforest and wet forest.

Identification
Bolton (2000) - A member of the signeae complex in the Strumigenys godeffroyi-group. Of the species grouped here with signeae (see under signeae-complex), Strumigenys ahares is immediately isolated by its peculiarly shaped mandibles. In full-face view they have concave outer and convex inner margins, the latter touching at full closure through the basal part of their length and separating and diverging distally; this specialisation is unique in the group.

The closely related species signeae and Strumigenys valefor both have a conspicuous series of freely laterally projecting stout hairs on the dorsolateral margin of the head. The first hair in the series is located anterior to the level of the apex of the scrobe and the remainder form a sequence that diminishes in length to the occipital corner. The presence of a broad cuticular lamella on the inner mandibular margin is diagnostic of signeae. This feature is by no means unique in the regional fauna but the structure as described above, coupled with the pilosity characters noted, will isolate signeae from all other species in the group. Under light microscopy the mandibular lamella appears thin and translucent but with electron microscopy it appears opaque and solid. This is because light can penetrate the thin cuticular sheet but an electron beam is completely reflected by it. S. valefor lacks the mandibular lamella but does have a very narrow cuticular rim or carina for part of the length of the inner mandibular margin; this is extremely slender and inconspicuous by comparison with signeae. The head of valefor is rather more slender than than that of signeae and its scapes tend to be longer: valefor CI 67-71, SI 83-88; signeae CI 73-78, SI 72-79.

The remaining four species grouped here (Strumigenys izepara, Strumigenys sublaminata, Strumigenys uichancoi, Strumigenys virgila) do not have a row of coarse marginal hairs on the head, nor do they show any striking oddities in mandibular morphology like those mentioned above. However, virgila has a characteristic apical mandibular dentition that consists of an intercalary tooth with two denticles between it and the apicoventral tooth; usually there is also a denticle between the intercalary tooth and the apicodorsal spiniform fork tooth. S. virgila also has a large lateral spongiform lobe on the petiole (small in the others). The dorsal margin of this lobe is very high on the side and extends the length of the node, as is usual in the godeffroyi-complex but is otherwise unknown in the species here grouped with signeae.

Of the final three species izepara and sublaminata have relatively short scapes, SI 62-69. S. sublaminata has shorter mandibles (MI 35-39) than izepara (MI 47). S. izepara also has short standing hairs present at the highest point of the vertex (absent from sublaminata), has the pronotal dorsum mostly smooth (densely reticulate-punctate in sublaminata), and has the hairs on the first gastral tergite slender and simple (stout and weakly remiform in sublaminata).

The final species, uichancoi has longer scapes than the two just discussed, SI 85. S. uichancoi has the pronotal dorsum smooth and has a broad lamella on the propodeal declivity. It also lacks a freely laterally projecting apicoscrobal hair. Instead the entire dorsolateral margin, from the frontal lobe to the occipital corner, has a dense row of small slender anteriorly curved hairs that are all about the same size and shape.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Brunei Darussalam, Indonesia, Malaysia, Philippines, Singapore. Oriental Region: Thailand.

Nomenclature

 *  signeae. Strumigenys signeae Forel, 1905c: 10 (w.) INDONESIA (Java). See also: Bolton, 2000: 826.

Worker
Bolton (2000) - TL 2.5-2.9, HL 0.65-0.80, HW 0.47-0.60, CI 73-78, ML 0.30-0.38, MI 46-50, SL 0.36-0.44, SI 72-79, PW 0.27-0.32, AL 0.66-0.77 (20 measured).

Characters of signeae-complex. With head in full-face view outer margin of mandible more or less straight. Inner margin of mandible with a broad translucent cuticular lamella that extends from base nearly to the preapical tooth; lamella broadens slightly from base toward apex and is broadest just before its termination, where it is about one-third the width of the mandible. In most poplilations the lamella is abruptly truncated at its apex, just proximal of the preapical tooth, but in some it is more rounded and tapered toward its apex. Dorsolateral margin of head with a freely laterally projecting stout remiform hair just anterior to level of apex of scrobe and another in apicoscrobal position; margin posterior to this with 2-3 similar but shorter projecting hairs. Cephalic dorsum with a transverse row of 4-6 erect hairs at occipital margin; without standing hairs anterior to this. Pronotal humeral hair remiform, pronotal dorsum otherwise without erect hairs. Mesonotum with at least a single pair of erect remiform hairs anteriorly; usually also with 1-2 other, much shorter, erect pairs posteriorly. Dorsal alitrunk sometimes entirely densely punctate to reticulate-punctate but this sculpture usually weaker and more diffuse on pronotal dorsum where it is frequently partially to mostly effaced. Side of alitrunk with pleurae and propodeum mostly to entirely smooth. Petiole node in dorsal view broader than long, reticulate-punctate. In profile lateral spongiform lobe of petiole small, confined to posterolateral portion of node. Disc of postpetiole usually more or less smooth medially and with weak punctulate sculpture peripherally, less commonly entire disc smooth; in some even the centre of the disc with superficial sculpture. First gastral tergite with elongate stout weakly remiform hairs.

A small pale worker from Bogor, Java, measures only TL 2.1, HL 0.56, HW 0.41, CI 73, ML 0.27, MI 48, SL 0.32, SI 78, PW 0.24, AL 0.53. This is probably a first-brood worker from an incipient colony.

Type Material
Bolton (2000) - Syntype workers, INDONESIA: Java, Bogor ( = Buitenzorg), 1904 (K. Kraepelin) [examined].

References based on Global Ant Biodiversity Informatics

 * Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Forel A. 1905. Ameisen aus Java. Gesammelt von Prof. Karl Kraepelin 1904. Mitt. Naturhist. Mus. Hambg. 22: 1-26.
 * Kishimoto-Yamata K., F. Hyodo, M. Matsuoka, Y. Hashimoto, M. Kon, T. Ochi, S. Yamane, R. Ishii, and T. Itioka. 2012. Effects of remnant primary forests on ant and dung beetle species diversity in a secondary forest in Sarawak, Malaysia. Journal of Insect Conservation DOI 10.1007/s10841-012-9544-6
 * Mezger D., and M. Pfeiffer. 2011. Partitioning the impact of abiotic factors and spatial patterns on species richness and community structure of ground ant assemblages in four Bornean rainforests. Ecography 34: 39-48.
 * Mezger D., and M. Pfeiffer. 2011. Partitioning the impact of abiotic factors and spatial patterns on species richness and community structure of ground assemblages in four Bornean rainforest. Ecography 34: 39-48.
 * Pfeiffer M., D. Mezger, and J. Dyckmans. 2013. Trophic ecology of tropical leaf litter ants (Hymenoptera: Formicidae) - a stable isotope study in four types of Bornean rain forest. Myrmecological News 19: 31-41.
 * Pfeiffer M., and D. Mezger. 2012. Biodiversity Assessment in Incomplete Inventories: Leaf Litter Ant Communities in Several Types of Bornean Rain Forest. PLoS ONE 7(7): e40729. doi:10.1371/journal.pone.0040794
 * Pfeiffer M., and D. Mezger. 2012. Biodiversity Assessment in Incomplete Inventories: Leaf Litter Ant Communities in Several Types of Bornean Rain Forest. PLoS ONE 7(7): e40729. doi:10.1371/journal.pone.0041111
 * 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
 * Philpott S.M., P. Bichier, R.A. Rice, and R. Greenberg. 2008. Biodiversity conservation, yield, and alternative products in coffee agroecosystems in Sumatra, Indonesia. Biodivers. Conserv. 17: 1805-1820. Data obtained from Stacy Philpott
 * Silva T. S. R., and R. M. Feitosa. 2019. Using controlled vocabularies in anatomical terminology: A case study with Strumigenys (Hymenoptera: Formicidae). Arthropod Structure and Development 52: 1-26.
 * Sukimin S., M. Mohamed, and H. Aris. 2010. Ant diversity of Maliau Basin Conservation Area, Sabah, Malaysia. Journal of Tropical Biology and Conservation 6:89-101.