Azteca nigricans Forel

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: 40-41

publication ID

21311

publication LSID

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persistent identifier

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scientific name

Azteca nigricans Forel
status

 

Azteca nigricans Forel   HNS   1899

Figures 2,4A,5.

Azteca fasciata var. nigricans Forel   HNS   , 1899:122. Unique syntype queen: Panama, Bugaba, Volcan de Chiriqui (Champion) [ MHNG]   (examined). Raised to species: Longino 1996:141.

Azteca   HNS   JTL-002: morphospecies code used in Longino 1996:141.

Queen characters. Measurements (n=5): HLA 1.55 (1.48-1.64), HW 1.09 (1.05-1.17), SL 0.76 (0.74-0.79), CI 71 (70-73), SI 50 (48-51).

Palpal formula 5,3; middle and hind tibia with prominent pectinate apical spur; dorsal surface of mandible coarsely punctate, puncta bearing stiff erect setae, mandible appearing bristly; medial and lateral clypeal lobes at about same level; head subrectangular, posterior margin weakly excised medially; petiolar node short, broadly triangular; posteroventral petiolar lobe strongly convex from front to back; scape with sparse and inconspicuous erect setae, about as long as one third maximum width of scape; hind tibia with short inconspicuous suberect setae, longest of these about as long as one sixth maximum width of tibia (MTSC 5-10); side of head with 0-2 short setae near mandibular insertion, setae lacking elsewhere, posterior margin of head with sparse erect setae; pronotum with posterior row of erect setae; mesoscutum and scutellum with very sparse erect setae; propodeum with a few erect setae on sides, none on dorsomedial area; petiolar node with rim of whitish erect pubescence, a few longer erect setae on lower sides but in profile with none projecting above apex, posteroventral lobe with abundant long setae; gastral terga with very sparse erect setae; general body color dark brown, the following lighter yellow brown: thin strip of anterior clypeus and area near mandibular insertions, thin anterior and posterior bands on gastral terga, gastral sterna.

Worker characters. Measurements (n=4): HLA 1.31 (1.04-1.42), HW 1.09 (0.92-1.20), SL 0.73 (0.67- 0.77), CI 84 (83-88), SI 56 (54-64).

Palpal formula 5,3; middle and hind tibia with prominent pectinate apical spur; dorsal surface of mandible with abundant piligerous puncta, surface between puncta smooth and shining, variable extent of base faintly microareolate; medial and lateral clypeal lobes at about same level; head subquadrate with weakly convex sides, moderately excavate posterior margin; in lateral profile mesosoma compact, pronotum and mesonotum nearly forming a single convexity, with promesonotal suture very weakly impressed; scape with sparse, inconspicuous erect setae, length of setae about one half maximum width of scape; outer surface of hind tibia with a row of about 5 very short, inconspicuous, suberect setae; side of head lacking erect setae or with 1-2 near mandibular insertion; posterior margin of head with sparse erect setae; pronotum and mesonotum with sparse erect setae, dorsal face of propodeum lacking erect setae; color red brown.

Similar species. The bristly mandibles ally this species with A. forelii   HNS   and A. brevis   HNS   . Queens of A. nigricans   HNS   are smaller than queens of A. forelii   HNS   (Fig. 4A). Queens of A. brevis   HNS   have shorter scapes than queens of A. nigricans   HNS   (SI 39-43 versus 50-52, respectively). Workers of A. brevis   HNS   are distinguished from workers of A. nigricans   HNS   by the reduced number of setae on the hind tibia, 0-2 on A. brevis   HNS   versus> 5 on A. nigricans   HNS   .

Range. Panama, Costa Rica, Guatemala.

Biology. Longino (1996) reviewed the taxonomy and biology of this species. It is found in wet forest habitats, where it nests in live stems of a wide variety of trees, including Cecropia insignis   , Inga   , Pentaclethra macroloba   HNS   , Erythrina poeppigiana   (Fabaceae), Tetrathylacium costaricensis   , Licania   , Phoebe chavarriana   (Lauraceae), and Dendropanax arboreus   (Araliaceae). The workers make small holes in shoot tips of live trees, leading to irregular cavities containing brood. The walls of the cavities are lined with abundant coccoid Hemiptera. As flushes of new growth occur, the ants move into the new shoots and progressively abandon older chambers lower in the branch. Colonies are polydomous, with brood distributed in multiple nests. Colonies can be large, occurring in large portions of large canopy trees. In contrast to the similar species A. brevis   HNS   , workers do not use carton construction and often have exposed foragers on stems. Although new alate queens are often dispersed in the nests of a colony, I have never found a physogastric colony queen. This suggests that colonies are monogynous, with the colony queen hidden in one of the many nests that occur in tree crowns. Brood must be transported externally to new nests.

Comments. In Longino (1996), two morphospecies, JTL-001 and JTL-002, were considered close to or conspecific with A. nigicans   HNS   . The former was discovered to be A. brevis   HNS   , and the measurements of the latter cluster with the holotype queen of A. nigricans   HNS   . The separateness of A. brevis   HNS   and A. nigricans   HNS   was further supported when the two species were found to be sympatric in Corcovado National Park. I found both species nesting in the canopy of a large Licania   tree in Corcovado National Park. At the time I did not understand the species boundaries, but in the field I observed behavioral differences. In my field notes I commented that Azteca   HNS   high in the crown produced a black crusty carton on the stem surfaces and were rarely seen exposed on the surface, while another group of Azteca   HNS   lower in the crown looked similar but did not make carton and were active and exposed on the surface of the live stems in which they nested. The former were A. brevis   HNS   and the latter A. nigricans   HNS   .

Additional material examined. COSTA RICA: Heredia: La Selva Biological Station , 10°26'N, 84°01'W, 50m , numerous collections and dates (ALAS, Longino, Wetterer) - workers, queens [ INBC] GoogleMaps   ; 11km ESE La Virgen , 10°21'N, 84°03'W, 300m , 21 Mar - 6 Apr 2004 (ALAS) - worker [ INBC] GoogleMaps   ; 11km SE La Virgen , 10°20'N, 84°04'W, 500m , numerous collections and dates (ALAS) - workers [ INBC] GoogleMaps   ; Limón: Parismina , 10°12'N, 83°38'W, 5m , 18 Oct 1926 (F. Nevermann) - worker, alate queen [ USNM] GoogleMaps   ; Puntarenas: Sirena, Corcovado National Park , 8°29'N, 83°36'W, 5m , 7 Sep 1982 (J. Longino) - workers GoogleMaps   ; same locality, 3 Jul 1987 (L. Tennant) - worker GoogleMaps   ; GUATEMALA: Escuintla: Finca Caobanal , 14°06'N, 90°40'W, Feb 1993 (J. Gilardi) - workers GoogleMaps   .

MHNG

Switzerland, Geneva, Museum d'Histoire Naturelle

INBC

Costa Rica, Santo Domingo de Heredia, Instituto Nacional de Biodiversidad (INBio)

USNM

USA, Washington D.C., National Museum of Natural History, [formerly, United States National Museum]

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Hymenoptera

Family

Formicidae

Genus

Azteca