Azteca coeruleipennis Emery

Longino, J. T., 2007, A taxonomic review of the genus Azteca (Hymenoptera: Formicidae) in Costa Rica and a global revision of the aurita group., Zootaxa 1491, pp. 1-63 : 25-26

Azteca coeruleipennis Emery 1893

Figures 2,4A,5,7.

Azteca coeruleipennis Emery 1893:130. Lectotype queen: Costa Rica, western slope (Alfaro) [label: " Alajuela, Cecropia , III 90 "] [ MCSN] (examined).

Queen characters. Measurements (n=5): HLA 1.93 (1.74-1.98), HW 1.48 (1.35-1.53,8), SL 0.98 (0.90- 1.03,8), CI 77 (75-78), SI 51 (50-53).

Palpal formula 6,4; middle and hind tibia with prominent pectinate apical spur; dorsal surface of mandible faintly microareolate, dull, with sparse small piligerous puncta, setae in puncta short, larger puncta with long setae near masticatory margin; medial and lateral clypeal lobes at about same level (medial lobe not projecting anteriorly); head quadrate, with sides slightly converging posteriorly; petiolar node low, bluntly rounded; posteroventral petiolar lobe evenly convex, shallow, not strongly developed; scape with abundant fine erect setae, about as long as one half maximum width of scape; middle and hind tibia with abundant erect setae, longest of these about as long as maximum width of tibia (MTSC 20-30); sides of head below level of eyes with 1-2 erect setae, sides of head posterior to eyes with 0-2 short erect setae; posterior margin of head with abundant long curved setae; pronotum with abundant long setae on posterior third; mesoscutum, scutellum, and propodeum with abundant setae, those on scutellum and propodeum longer than those on mesoscutum; petiolar node with variable number of long setae on apex, abundant long setae on posteroventral lobe; all gastral terga with abundant erect setae; color dark brown to black.

Worker characters. Measurements (n=3): HLA 1.00 (0.97-1.08), HW 0.93 (0.91-0.99), SL 0.71 (0.70- 0.72), CI 94 (91-94), SI 72 (66-72).

Palpal formula 5,3; middle and hind tibia with prominent pectinate apical spur; dorsal surface of mandible largely smooth and shining, grading to dull, microareolate sculpture at base, with sparse small piligerous puncta, setae in puncta short, larger puncta with long setae near masticatory margin; medial and lateral clypeal lobes at about same level, medial lobe at most weakly projecting beyond lateral lobes; head with convex sides, strongly cordate posterior margin; mesosoma in lateral profile with promesonotum forming a continuous convexity or mesonotum somewhat elevated above pronotum; posterior mesonotum drops abruptly to metanotal groove, dorsal face of propodeum and broad metanotal groove form a flat, step-like junction with posterior mesonotum; scape and tibia with abundant erect setae, length of setae about one half maximum width of scape or tibia, respectively; sides of head with abundant erect setae from mandibular insertions to level of eye, extending variable distance posterior to eye, often leaving posterior portion devoid of setae; posterior margin of head with abundant erect setae; promesonotum with abundant long erect setae; dorsal face of propodeum with no erect setae or with sparse setae that are much shorter than those of promesonotum; color yellow orange.

Similar species. Among the Cecropia ants, A. coeruleipennis is most easily confused with A. alfari and A. ovaticeps . The presence of tibial setae, the distinctive shape of the mesonotum, and the 6,4 palpal formula will separate A. coeruleipennis from A. alfari and A. ovaticeps .

Range. Mexico to Costa Rica.

Biology. The taxonomy and biology of A. coeruleipennis is reviewed in Longino (1989b, 1991a, b). The species is an obligate Cecropia ant. It occurs in highly seasonal habitats. Nests are dispersed in both the tree bole and outer branches, with brood dispersed throughout the nesting space.

Comments. Prior to this report I had never investigated palpal formula in Azteca . It was surprising to discover that A. coeruleipennis had a palpal formula of 6,4, while all other Cecropia ants have 5,3. A palpal formula of 6,4 is probably plesiomorphic in the genus, which implies that A. coeruleipennis might be a very old Cecropia ant and sister to all the other Cecropia ants. Perhaps this species has survived the arrival of newer Cecropia ants by being a dry-forest specialist, a habitat that is marginal for Cecropia trees.

Material examined. See Longino (1991b).