Tetheamyrma subspongia

The two worker types were collected from a Winkler sample of forest leaf litter.

Identification
There are two species in the genus. They can be separated using the following couplet by General and Buenavente (2018):

Tetheamyrma bidentata - Spongiform tissue absent from ventral surfaces of petiole, postpetiole, and first gastral sternite; antenna with 10 segments; frontal carina just reaching level of anterior margin of eye; anteromedian clypeus produced into a bidentate process (Philippines).

Tetheamyrma subspongia - Spongiform tissue present on ventral surfaces of petiole, postpetiole, and first gastral sternite; antenna with 11 segments; frontal carina not reaching level of anterior margin of eye; anteromedian clypeus medially emarginate but not produced into a bidentate process (Malaysia)

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

Castes
Known only from the worker caste.

Nomenclature

 *  subspongia. Tetheamyrma subspongia Bolton, 1991: 10, figs. 16, 17 (w.) BORNEO.

Worker
Holotype. TL 2.3, HL 0.55, HW 0.51, CI 92, SL 0.32, SI 63, PW 0.36, AL 0.66. Maximum diameter of eye 0.08 (0.16 x HW), the eye with only about 10 ommatidia in total. Mandibles smooth. Head capsule everywhere extremely finely and densely sharply reticulate-rugose and with dense short soft curved pilosity. Promesonotum sculptured as head. Sloping propodeal dorsum sculptured to level of spines but declivity thereafter smooth and shining. Petiole and postpetiole both much broader than long in dorsal view and more finely sculptured than the promesonotum. Gaster smooth and shining between conspicuous pits from which hairs arise. All dorsal surfaces of alitrunk, waist and gaster with dense soft curved pilosity except for the propodeum behind its highest point, which lacks hairs. Colour medium brown, the appendages lighter.

Paratype. TL 2.2, HL 0.54, HW 0.49, CI 91, SL 0.30, SI 61, PW 0.35, AL 0.62. Maximum diameter of eye 0.07 (0.14 x HW). As holotype.

General and Buenavente (2018) - Monomorphic ants. In full-face view, head widest behind compound eyes. Posterior margin of head shallowly emarginate. Lateral head margin slightly converging anteriorly. Antennae with 11 segments, with very large 2-segmented apical club. Antennal scape short, just exceeding posterior margin of compound eye. Antennal scape shallowly reticulate, with short decumbent hairs. Antennomeres 3 - 9 much broader than long. Antennal scrobe absent. Compound eye small, composed of about 10 ommatidia, located laterally, just forward of midlength of head. Frontal carina short, barely reaching anterior margin of eye. Frontal lobes wide, completely concealing torulus, wider than median clypeus inserted between them. Median clypeus narrowly inserted between frontal lobes. Median clypeus narrowly bicarinate. Anterior clypeus medially with a pair of setae straddling midpoint. Anterior clypeal margin medially emarginate. Mandible triangular, mostly smooth. Mandibular dentition composed of six teeth without a diastema. Basal external margin of mandible smooth. Head densely rugo-reticulate dorsally, laterally, and ventrally, except for smooth genal bridge. Frontal lobes sculptured. Head pilosity composed of fine flexuous hairs of varying lengths. In lateral view, palp formula 2,2. Occipital carina present. Mesosomal outline smoothly convex. Metanotal groove impressed. Mesosoma densely rugo-reticulate dorsally and laterally. Metapleuron and propodeal declivity rugo-reticulate. Mesosomal pilosity composed of erect hairs on dorsum of various lengths, except for glabrous propodeal declivity. Propodeum with short, acute, triangula spines. Infradental lamella between propodeal spine and metapleural lobe present. Metapleural lobe low and rounded. Propodeal spiracle conspicuous, more than one propodeal spiracle diameter from base of propodeal spine. Petiole microreticulate, nodiform. Anterodorsal corners of petiole node rounded. Anteroventral petiolar process present. Postpetiole microreticulate. Anterior face of postpetiole rounded smoothly into dorsal face. Anteroventral postpetiolar process absent. Spongiform tissue present on venter of petiole, postpetiole, and first gastral sternite. Sting simple and functional. Spine absent from mesotibia and metatibia. Petiole node transverse, broader than long. Petiole and postpetiole microreticulate. Dorsum of gaster smooth between piliferous punctures. Gastral pilosity composed of dense flexuous hairs.

Type Material
Holotype worker, East Malaysia: Sabah, Poring Hot Springs, Langanan River, 850 m, 14.v.87, no. 25a (Lobl & Burckhardt). Paratype, one worker with same data as holotype.

References based on Global Ant Biodiversity Informatics

 * Bolton B. 1991. New myrmicine genera from the Oriental Region (Hymenoptera: Formicidae). Systematic Entomology 16:1-13.
 * 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., 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.0040928
 * 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