Polyrhachis spinosa

The lone occurrence record of this species from Sulawesi is from a copal sample.

Identification
A member of the Polyrhachis sexspinosa species group.

Kohout (2008) - In his original description, Mayr (1867) illustrated both castes and listed characters separating P. spinosa from the closely allied species, Polyrhachis sexspinosa, Polyrhachis rugifrons and P. bubastes. Some of the more useful characters distinguishing this group of species are as follows. The occipital margins of P. sexspinosa and P. spinosa feature lateral angular prominences or lobes that are clearly visible in full face view. These lobes are weakly developed and barely visible in P. bubastes and P. rugifrons. In profile, the pronotal dorsum is strongly swollen and dome-like in P. bubastes and P. sexspinosa, while it is only moderately convex in the other two species. The pronotal spines are strongly curved forwards in P. sexspinosa, P. spinosa and P. bubastes, but in P. rugifrons they are short, straight and project laterally, almost at right angles to the main axis of the body. A mesopleural tooth is strongly developed in P. bubastes, while it is a simple, non-dentiform lobe in P. sexspinosa and P. rugifrons and virtually absent in P. spinosa. Although the propodeal spines are variable in length and degree of elevation in P. sexspinosa, they are generally long and vertical to the main axis of the body, or even inclined anteriorly. The propodeal spines are curved backwards in the other species, but while they are long in P. rugifrons and P. spinosa, they are distinctly shorter in P. bubastes. The form of the petiolar spines varies considerably among the species. In P. rugifrons they are long and slender and embrace the base of first gastral segment. In P. sexspinosa they are long, slender, strongly elevated and weakly curved. The spines are short, slender, only weakly elevated, and divergent in P. bubastes, while they are long, relatively thick, strongly elevated and subparallel in P. spinosa. Polyrhachis sexspinosa and P. rugifrons have the body covered with mostly yellowish or off-white, rather dense pubescence, that almost completely or partly hides the underlying sculpturation respectively. In contrast, P. bubastes and P. spinosa have the body clothed with numerous, rusty brown or black, short, erect hairs that do not mask the underlying sculpturation.

Kohout (2008) - The two sexspinosa-group species known from Sulawesi are distinguished as follows:


 * Pronotal spines short, straight, directed laterally in virtually right angle to main axis of body . . . . . Polyrhachis rugifrons


 * Pronotal spines bull-horn shaped, curving laterally and anteriorly . . . . . Polyrhachis spinosa

Distribution
Kohout (2008) - A single specimen from copal appears to be the only record of this species from Sulawesi. Polyrhachis spinosa is also known from Halmahera and Morty I. (= Morotai I. in Maluku Utara).

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

Nomenclature

 *  spinosa. Polyrhachis spinosa Mayr, 1867a: 43, pl. 2, fig. 2 (w.q.) INDONESIA (Halmahera I.). Combination in P. (Myrmhopla): Emery, 1925b: 191. Junior synonym of bubastes: Bolton, 1975c: 6. Revived from synonymy: Kohout, 2008a: 306.

Type Material
Kohout (2008) - Syntype worker, queen. INDONESIA, HALMAHERA, Dodinga (Forsten), (examined).