Tetramorium flagellatum

Identification
Sorger (2011) - Differentiation between Tetramorium lucyae and T. flagellatum is difficult, and careful examination and measurements are necessary in order to successfully and reliably identify these species.

There are three distinguishing characters: maximum hair length (on head, mesosoma and tibiae), frons sculpture and total length (although the latter can be used only with a larger nest sample: at least 20 specimens). None of these characters should be used for identification in isolation; only a combination of all characters provides a clear picture of the distinctions between the species. A combination of MHLH, MHLM and MHLT is vital for identification; in addition, it is recommended to use a nest sample of more than 5 specimens where possible, given variation among individuals.

All measurements are in millimetres and presented as minimum-mean-maximum values.

Maximum hair lengths on head, mesosoma and tibiae: T. lucyae (0.40–0.48–0.59 MHLH; 0.46–0.51–0.58 MHLM; 0.22–0.30–0.34 MHLT) has longer hairs than T. flagellatum (0.30–0.35–0.40 MHLH; 0.34–0.41–0.44 MHLM; 0.10–0.17–0.22 MHLT) overall. Two single specimens in the studied sample overlap at a single value each: (MHLT: 0.40 mm; MHLT: 0.20 mm).

Frons sculpture: Sculpture on head frons is more longitudinally oriented in T. flagellatum. However, this differential character is subtle—longitudinal rugae on frons (right at medial depression) are more irregular (“shaky”) in T. lucyae whereas, in comparison, rugae are rather straight in T. flagellatum.

Total length: T. flagellatum (3.28–3.55–3.80 TL) is smaller than T. lucyae (3.60–3.73–3.86 TL) overall. However, since the mean TL of T. lucyae lies within the overlapping range (3.60 to 3.80 mm TL) of the two species, a nest series of at least 20 specimens is necessary in order to calculate a mean value.

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

Nomenclature

 *  flagellatum. Tetramorium flagellatum Bolton, 1977: 122, fig. 48 (w.) BORNEO. See also: Sorger, 2011b: 5.

Worker
Sorger (2011) - Measurements of workers (range of 20 workers). Worker with smallest HW: HW 0.71; HL 0.76; CI 93; SL 0.57; SI 80; PW 0.52; ML 0.92; TL 3.34; MHLH 0.36; MHLT 0.17; MHLM 0.41. Worker with largest HW: HW 0.83; HL 0.90; CI 92; SL 0.64; SI 77; PW 0.62; ML 1.08; TL 3.80; MHLH 0.33; MHLT 0.19; MHLM 0.44.

Mean values of 20 workers: TL 3.55; MHLH 0.35; MHLT 0.17; MHLM 0.41.