Acanthostichus serratulus

Nests in rotten wood (Luederwaldt 1926).

Identification
Mackay (1996) - The workers of this species are very similar to those of Acanthostichus kirbyi, Acanthostichus quadratus and Acanthostichus lattkei. This species is somewhat intermediate between A. kirbyi and A. quadratus, and my first impulse was to synonymize these three species. In terms of the shape of the petiole and scape, it is similar to A. kirbyi. On the other hand, the sculpture of the dorsum of the petiole (relatively smooth and shining, with longitudinal troughs, sides angulate, the petiole of the lectotype is especially smooth) and the lack of lateral teeth on the clypeus are similar to those of A. quadratus. The dorsal surface of the petiole of A. kirbyi is lightly punctate. Other differences between A. serratulus and A. kirbyi can be found in the discussion section of A. kirbyi. Furthermore, the males of A. kirbyi and A. quadratus are different (see key). If synonymization was done, we would have a highly variable species. As the three taxa are consistently different, I feel it is best to continue to regard them as separate species.

Keys

 * Key to Acanthostichus workers
 * Key to Acanthostichus males

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Brazil, Paraguay.

Nomenclature

 *  serratulus. Typhlopone serratula Smith, F. 1858b: 111 (w.) BRAZIL. Mayr, 1887: 551 (m.); Emery, 1899c: 6 (l.). Combination in Acanthostichus: Mayr, 1887: 549. See also: Gallardo, 1918b: 9; Mackay, 1996: 165.

Worker
Mackay (1996) - (lectotype in parentheses): HL 0.89-(1.05), HW 0.76-(0.91), SL 0.41-(0.54), EL 0.03-(0.04), WL 1.05-(1.38), PW 0.35-(0.45), PL 0.34-(0.51), SI 46-(51), CI 86-(87)-88, PI 96-(114), SL/SW 2.54 (2.69)-2.92.

Mandibles without teeth; clypeus with medial tooth, but without lateral teeth; frontal carinae closely set, rounded anteriorly; occipital border concave; promesonotal suture moderately well differentiated on dorsum of mesosoma; propodeal spiracle located about halfway down from dorsum of propodeum; petiole slightly longer than broad, with angulate lateral borders which form longitudinal carinae, longitudinal troughs present, subpetiolar tooth concave ventrally (Fig. 38); femur not incrassate. Dorsum of petiole slightly roughened and sides of mesosoma and petiole with longitudinal striae.

Male
Mackay (1996) - HL 0.99, HW 1.01, SL 0.29, EL 0.56, WL 2.00, PW 0.39, PL 0.54, SI 29, CI 103, PI 139.

The male is very similar to that of Acanthostichus kirbyi, but differs in the shape of the petiole.

Type Material
Worker, BRAZIL: Amazonas, Vila Nova (seen). Lectotype worker (here designated) (BMNH). Lectotype labeled: 55 44; Typhlomynnex serratula; Type. Smith; syntype [round white label with light blue border); second specimen labeled: Brazil Villa [=Vila] Nova; Syntype; T. serratula Sm.; labeled syntype [second specimen is A. quadratus - both seen]. The male described by Mayr (1887) is apparently lost. A male specimen deposited in the USNM is labeled as A. serratulus, but is not associated with workers. The hand written label appears to be written by Emery (compared with labels of three type specimens of Camponotus obtritus Emery), and thus is presumably A. serratulus, as Emery described the male. It is very similar to the male of A. kirbyi, but differs in that the node of the petiole is bullet shaped, narrowed and pointed anteriorly. A second possible male in the USNM was collected from the West border of Mato Grosso, Brazil.

Typhlopone serratula

One worker syntype in. Labelled “Villa Nova,” and “55/44.” Acc. Reg.: “1855 no. 44 (June 22nd). Amazon. Villa Nova. Bought of Stevens. Collected by Mr Bates.”

The specimen is marked syntype as obviously two workers were originally mounted on the card, but one has long ago fallen off and cannot now be found.