Camponotus siamensis

This species has been known only from the type locality (Mukdahan Province, northeastern Thailand), where a nest was found in a small dead twig in a mixed deciduous forest.

Identification
Camponotus siamensis is similar to Camponotus lasiselene (China and Thailand) (Fig. 2) and Camponotus selene (China, India, and Myanmar) (Fig. 3). However, in the minor worker C. siamensis is clearly distinguished from C. selene by the following characteristics (see figures 2 and 3 for comparison):
 * 1) head rectangular, posterior margin weakly concave in C. siamensis (round, posterior margin roundly convex in C. selene)
 * 2) propodeum without spines, propodeal junction right angled in C. siamensis (with blunt spines in C. selene)
 * 3) dorsal outline of petiole roundly convex in C. siamensis (dorsal outline angulate in C. selene)
 * 4) abdominal segments III–VI micorpunctate in C. siamensis (smooth and shiny in C. selene).

Minor worker of C. siamensis can be easily separated from minor worker that of C. lasiselene by:
 * 1) posterior margin of head concave medially in C. siamensis (convex in C. lasiselene)
 * 2) dorsal outline of petiole roundly convex (dorsal outline angulate in C. lasiselene)
 * 3) propodeum without spines in C. siamensis (with spines in C. lasiselene)
 * 4) dorsum of mesosoma with less than 30 erect hairs in C. siamensis (over 60 erect hairs in C. lasiselene, see figures 1A and 2A for comparison).

Comparing with major worker, C. siamensis is easily separated from C. lasiselene by:
 * 1) head longer than broad in C. siamensis (almost as long as broad in C. lasiselene)
 * 2) propodeum without spines in C. siamensis (with short spines in C. lasiselene)
 * 3) pilosity sparse (dense but short in C. lasiselene)
 * 4) petiole superficially reticulate, with smooth and shining interspaces in C. siamensis (finely punctate in C. lasiselene)

Distribution based on Regional Taxon Lists
Oriental Region: Thailand.

Nomenclature

 * . Camponotus (Orthonotomyrmex) siamensis Jaitrong & Jeenthong, 2022: 34, figs. 1A-F (w.q.) THAILAND.

Type Material

 * Holotype (THNHM-I-24794, THNHM), minor worker, NE Thailand, Mukdahan Province, Chamcha-I District, Cheang Chang Niam Village, mixed deciduous forest (MDF), 8.VI.2007, W. Jaitrong leg., WJT07-TH-1075.
 * Paratypes. Seven minor workers (THNHM-I-24795 to THNHM-I-24801, THNHM) and 3 major workers (THNHM-I-24802 to THNHM-I-24804, THNHM), same data as holotype; 2 minor workers (THNHM-I-24805 to THNHM-I-24806, THNHM), NE Thailand, Mukdahan Province, Chamcha-I District, Kheang [Cheang] Chang Niam Village, dry evergreen forest (DEF), 4.IX.2007, W. Jaitrong leg.