Polyrhachis latona

Identification
Kohout (2013): When describing P. latona, Wheeler (1909) noted that his new species ‘is closely related to Polyrhachis relucens Latr., Polyrhachis mayri Roger [= P. illaudata Walker] and Polyrhachis proxima Roger’. He listed the smaller size, more approximate frontal carinae, different pilosity, shallower promesonotal and ‘mesoëpinotal’ notches in the lateral margins, differences in the shape and length of the pronotal and petiolar spines and several other characters as the main differences distinguishing his new species. Besides the characters indicated by Wheeler, P. latona also differs from the above species by having rather flat, mildly posteriorly protracted eyes.

Distribution
This taxon was described from Taiwan.

Nomenclature

 *  latona. Polyrhachis latona Wheeler, W.M. 1909d: 337 (w.) TAIWAN. Forel, 1912a: 79 (m.). Combination in P. (Myrma): Emery, 1925b: 201. Senior synonym of dorsorugosa: Wu & Wang, 1995: 167.
 * dorsorugosa. Polyrhachis latona var. dorsorugosa Forel, 1913f: 202 (w.m.) TAIWAN. Combination in P. (Myrma): Emery, 1925b: 201. Raised to species: Wang & Wu, 1991: 599. Junior synonym of latona: Wu & Wang, 1995: 167.

Description
Kohout (2013): Worker. Dimensions (syntypes cited first): TL c. 6.25-7.16, 6.30-7.26; HL 1.62-1.72, 1.65-1.84; HW 1.22-1.31, 1.26-1.34; CI 75-76, 73-78; SL 1.96-2.06, 2.03-2.21; SI 157-161, 156-166; PW 1.18-1.34, 1.25-1.40; MTL 1.93-2.09, 2.00-2.25 (2+10 measured).

Queen (not previously described). Dimensions: TL c. 8.62; HL 1.90; HW 1.42; CI 75; SL 2.25; SI 158; PW 1.78; MTL 2.31 (1 measured).

Queen larger than worker with usual characters identifying full sexuality, including three ocelli, complete thoracic structure and wings. Pronotal spines very short, about as long as basal width. Mesoscutum only marginally wider than long; lateral margins converging anteriorly into rather narrowly rounded anterior margin; median line distinct; parapsides virtually flat; mesoscutum in profile with anterior face widely rounding onto convex dorsum. Mesoscutellum weakly convex, not distinctly elevated above dorsal plane of mesosoma. Propodeum with lateral margins in profile somewhat angular at midlength, terminating in short ridges that are continued medially forming distinct, dorsally bowed carina dividing propodeal dorsum from declivity. Petiole with dorsolateral and lateral spines subequal in length; dorsal margin with distinct intercalary tooth. Sculpturation, pilosity, pubescence and colour very similar to worker.

Male in collection. Immature stages unknown.

Additional References

 * Kohout, R.J. 2013. A review of the Polyrhachis aculeata species-group of the subgenus Myrma Billberg (Hymenoptera: Formicidae: Formicinae), with keys and descriptions of new species. Australian Entomologist, 40, 137-171.