Tetramorium aptum

This species has been collected from litter samples in forest habitats. Heterick & Kitching (2022) collected this species in a pitfall trap within a lowland dipterocarp forest in Brunei.

Identification
A member of the Tetramorium scabrosum-species group.

Bolton (1977) - Amongst the species of the scabrosum-group T. aptum is easily distinguished as it is the only species having both petiole and postpetiole completely sculptured. In one or two other species of the group the post petiole may be faintly sculptured, but here the petiole is either broader than long or the relative size of the eye is outside the above range, or both.

Non-type specimens from West Malaysia: Malaya, Salangor, Kepong Waterworks Reserve, 22.viii.67 (R. Crozier) (MCZC; BMNH) match the description but the extreme apices of the propodeal spines are somewhat upcurved.

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

Nomenclature

 *  aptum. Tetramorium aptum Bolton, 1977: 115 (w.) THAILAND.

Worker
Holotype. TL 2.6, HL 0.60, HW 0.58, CI 97, SL 0.40, SI 69, PW 0.42, AL 0.70.

Mandibles striate; anterior clypeal margin entire. Frontal carinae distinct, extending back well beyond the level of the eyes but occipitally becoming confused with the reticulate sculpture. Antennal scrobes broad and shallow but easily discernible. Eyes relatively small, maximum diameter c. 0.12 so that the diameter of the eye is about 0.20 x HW. Propodeal spines moderate, quite stout, acute apically; metapleural lobes long, acute and triangular, about 0.66 x propodeal spine length. Petiole in profile with the node relatively long and low, the dorsal length of the node greater than the height of the tergal portion. In dorsal view the petiole node about as broad as long, narrowest in front and broadening posteriorly, and more narrowly rounded in front than behind. Dorsum of head weakly longitudinally rugulose to the level of the posterior margins of the eyes, behind this with increasingly numerous cross-meshes and the occipital region finely reticulate-rugulose. Spaces between the rugulae with fine, superficial punctulation, not conspicuous. Dorsal alitrunk finely reticulate-rugulose, most strongly developed on pronotum. Dorsal surfaces of both petiole and postpetiole covered with rugulose or reticulate-rugulose sculpture and with some punctulation. Gaster unsculptured. All dorsal surfaces of head and body with numerous erect or suberect hairs of varying length. On the head the longest hairs arise from the frontal carinae and on the alitrunk the longest hairs arise in a line along the sides of the dorsum. Antennal scapes with very short, curved pubescence and with a sparse series of longer, stouter hairs which are erect and project vertically. Dorsal (outer) surfaces of hind tibiae with erect or suberect short, stout hairs. Colour uniform light brown, and appendages yellowish.

Paratypes. As holotype but TL 2.6-2.7, HL 0.60-0.62, HW 0.56-0.60, CI 93-96, SL 0.38-0.40, SI 66-68, PW 0.42-0.44, AL 0.70-0.72 (2 measured). Maximum diameter of eye varies c. 0.12-0.13 which gives an eye diameter about 0.20-0.23 x HW.

Type Material
Holotype worker, Thailand: Nong Hoi, 21.vii.1975 (D. Jackson). Paratypes. 2 workers with same data as holotype (BMNH; ).

References based on Global Ant Biodiversity Informatics

 * Fontanilla A. M., A. Nakamura, Z. Xu, M. Cao, R. L. Kitching, Y. Tang, and C. J. Burwell. 2019. Taxonomic and functional ant diversity along tropical, subtropical, and subalpine elevational transects in southwest China. Insects 10, 128; doi:10.3390/insects10050128
 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Hashimoto Y., Y. Morimoto, and M. Mohamed. 2002. Species list of ground and leaf litter ants collected in Lower Kinabatangan. Lower Kinabatangan : scientific expedition 2002/ 13-18.
 * Hashimoto Y., Y. Morimoto, and M. Mohamed. 2003. Species List of Ground and Leaf Litter Ants Collected in Lower Kinabatangan. Pp 13-18. In Lower Kinabatangan Scientific Expedition 2002, 176 pp. ISBN-13: 983-2369-11-8
 * Lu Z., K. Li, N. Zhang, and Y. Chen. 2016. Effects of lac-corn agroforest ecosystem on ground-dwelling ant diversity and functional groups. Chinese Journal of Eco-Agriculture 24(1): 81-89.
 * Lu Z., K. Li, N. Zhang, and Y. Chen. 2017. Diversity and indicator species of leaf-litter ants in Eucalyptus grandis plantations and secondary natural forests. Forest Research 29(4): 576-580
 * 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
 * Roncin E. 2002. Two new Tetramorium species (Hymenoptera: Formicidae) from Vietnam with a discussion of the mixtum, tonganum, and scabrosum groups. Sociobiology 40: 281-292.
 * Xu Z. 1998. A report of fourty-one ant species newly recorded in China from Xishuangbanna District of Yunnan Province (Hymenoptera: Formicidae). Zhongguo Xue Shu Qi Kan Wen Zhai 4: 1119-1121.
 * Yamane S., T. Itino, and A.R. Nona. 1996. Ground ant fauna in a Bornean dipterocarp forest. Raffles Bulletin of Zoology 44(1): 253-262.
 * Yamane Sk., T. Itino, and A. Rahman Nona. 1996. Ground ant fauna in a Bornean dipterocarp forest. The Raffles Bulletin of Zoology 44(1): 253-262.
 * Zryanin V. A. 2011. An eco-faunistic review of ants (Hymenoptera: Formicidae). In: Structure and functions of soil communities of a monsoon tropical forest (Cat Tien National Park, southern Vietnam) / A.V. Tiunov (Editor). – M.: KMK Scientific Press. 2011. 277 р.101-124.