Polyrhachis quadrispinosa

The type series of Polyrhachis quadrispinosa was collected from a dead twig hanging on a tree in a rubber tree plantation near a limestone cave.

Identification
Polyrhachis quadrispinosa is similar to Polyrhachis cedarensis, Polyrhachis hexacantha, Polyrhachis ops, Polyrhachis phryne and Polyrhachis sidnica (all from Australia) in having long propodeal spine and four long petiolar spines dorsally and lacking standing hairs on body.

Polyrhachis quadrispinosa is easily distinguished from P. cedarensis by the following characteristics:
 * 1) median spines on petiole shorter than lateral spines (slightly longer than lateral spines in P. cedarensis)
 * 2) head macropunctate without striation (with longitudinal striation in P. cedarensis)
 * 3) head round, posterolateral corner of head broadly convex (head subrectangular, posterolateral corner of head distinctly convex as in P. cedarensis)

Polyrhachis quadrispinosa differs from P. hexacantha by:
 * 1) pronotum in dorsal view, with anterolateral corner roundly convex without process or spine (with distinct blunt spine in P. hexacantha)
 * 2) pronotum punctate, with irregular striation (without striation in P. hexacantha)
 * 3) propodeal spine entirely punctate (base of propodeal spine somewhat smooth and shiny in P. hexacantha)

Polyrhachis quadrispinosa can be distinguished from P. ops by:
 * 1) propodeal spine long, longer than broad at base (shorter than broad at base in P. ops)
 * 2) head round (head subrectangular in P. ops)
 * 3) with pronotum in dorsal view, anterolateral corner roundly convex without produced conner or spine (right-angled in P. ops).

Polyrhachis quadrispinosa can be separated from P. phryne by the following characteristics:
 * 1) pronotum in dorsal view, anterolateral corner roundly convex without produced corner or spine (with blunt angle in P. phryne)
 * 2) head and mesosoma macropunctate (puncto-reticulate in P. phryne)
 * 3) propodeal spine long, longer than its base (shorter than or about the same length of its base in P. phryne).

Polyrhachis quadrispinosa is separated from P. sidnica by:
 * 1) in dorsal view metanotal groove distinct (invisible in P. sidnica)
 * 2) in profile propodeal spine straight (slightly curved upward in in P. sidnica)
 * 3) head in full-face view, eye weakly convex, its outer margin slightly extending beyond lateral margin of head (distinctly convex, distinctly extending beyond lateral margin of head in P. sidnica)
 * 4) anterolateral corner in dorsal view roundly convex, not produced as process or spine (produced as a short tooth or denticle in P. sidnica)

Distribution based on Regional Taxon Lists
Indo-Australian Region: Malaysia. Oriental Region: Thailand.

Nomenclature

 * . Polyrhachis quadrispinosa Jaitrong & Noon-anant, in Jaitrong et al., 2023: 305, figs. 1A, 7, 8 (w.q.) THAILAND.

Type Material

 * Holotype worker (THNHM-I-00027172, THNHM), S Thailand, Trang Province, Palian District, Ban Li Phang, near Khai Ting Cave, rubber tree plantation, 7º9′35′′N, 99º48′01′′E, 19.V.2022, W. Jaitrong leg., TH22-WJT-155.
 * Paratypes: 14 workers (THNHM-I-00027173 to THNHM-I-00027183 and THNHM-I-00027185 to THNHMI-00027187, THNHM), 1 worker (SKY190522-1, SKYC) and 1 queen (THNHM-I-00027188, THNHM), same data as holotype.