Azteca sericeasur

Azteca sericeasur occurs in moist to wet forest habitats. Queens establish in live stems of understory trees, near the base. Mature colonies are polydomous and dispersed. Foraging columns extend across low vegetation and on the forest floor, connecting multiple small pavilions made of carton (paper-like material constructed by the ants from masticated plant fibers). Clusters of workers and brood occur in the pavilions, and the pavilions may cover membracids and pink scale insects, which the ants tend. Thus the queen is located in a permanent and well-protected site, while the colony is widely spread in a large number of small ephemeral nests. (Longino 2007)

Identification
Longino (2007) - The shape and size of the queen head distinguishes this species from all others except Azteca sericea. It differs from A. sericea in the presence of erect setae on the posterior margin of the head. It is very similar to Azteca velox, differing only in the larger size. Azteca gnava and Azteca instabilis are similar but larger. Azteca gnava has the head solid dark brown; A. sericeasur has much of the anterior and lateral head light orange brown. Azteca instabilis has large ocelli (OCW > 0.20mm); A. sericeasur has small ocelli (OCW about 0.10mm).

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica, Guatemala, Mexico, Panama.

Biology
Longino (2007) - Along the Río San Luis near Monteverde, I found workers coming and going from a fissure at the base of a live Xanthoxylem (Rutaceae) at a pasture edge. A colony of Camponotus novogranadensis was using the same entrance, in an apparent case of parabiosis. I have several observations of colonies from the Osa Peninsula. One colony was spread over an area of several square meters, in the dead, hollow core of a live Chimarrhis parviflora (Rubiaceae), in nearby dead sticks, and filling hollow stems of an adjacent Tetrathylacium costaricensis plant (Flacourtiaceae). The Tetrathylacium contained workers, small brood, and mealybugs, but no sexuals or large brood. Small carton nests covered some of the stems and nest entrances. The dead core of the Chimarrhis contained a small pocket of carton, in which I found the grossly distended colony queen and abundant small brood. In another case I found workers streaming through low vegetation. A nest was in a small sapling; the lowest part of the nest was 4m above the ground. There were numerous small cavities and knotholes in the trunk; these were all filled with workers and brood. The lowermost knothole was covered with a carton nest, and the bulk of the workers were in the carton portion. I looked in the carton and in all the knotholes, but I never found a queen. Leanne Tennant, in her study of Tetrathylacium costaricensis in Corcovado, found at least two of her study plants inhabited by A. sericeasur. Males may be produced in large numbers in the small satellite nests. In August, 1982, I observed a series of carton shelters on vine stems at the base of a buttressed tree, and they were packed with hundreds of adult males. Alate queens are few in collections; two were collected in October and one in July. Nest series with alate queens have been taken twice, both in July. I collected a founding queen in the internode of a Cecropia sapling at Estacion Pitilla in the Guanacaste Conservation Area, and Joel Dunn found an incipient colony in a Cordia bicolor plant near Monteverde.

The queens are generally setose ants, with abundant fine flexuous setae on most body parts. An exception was the queen from the Chimarrhis plant described above. This queen was almost completely devoid of erect setae anywhere on the body, including the tibiae, and the pubescence was sparse and patchy. When collecting from this colony, it took me more than an hour to locate the colony center, chop into the Chimarrhis tree, and extract the physogastric queen. This is probably the oldest queen I have examined, the others being alates or foundresses in incipient colonies (and thus more easy to locate and collect). It may be that once queens establish and become sedentary in the middle of a large colony, they gradually become depilated, perhaps through constant grooming by workers.

Philpot et al. (2018) found this ant was a dominant species in shade coffee plantations in Chiapas, Mexico. Nests were found in the shade and coffee trees. The presence of an A. sericeasur nest had a negative effect on the colonization of twigs by other species of ants.

Nomenclature

 *  sericeasur. Azteca sericeasur Longino, 2007: 46, figs. 3, 4A, 5, 6E, 6F, 7 (w.q.) COSTA RICA.

Worker
(n=9): HLA 1.32 (1.10–1.69), HW 1.31 (1.08–1.76), SL 1.09 (0.99–1.26), CI 99 (96–104), SI 83 (75–90).

Palpal formula 6,4; middle and hind tibia with prominent pectinate apical spur; dorsal surface of mandible smooth and shining, with moderately abundant small piligerous puncta, setae in puncta short, erect, larger puncta with long setae near masticatory margin; medial and lateral clypeal lobes at about same level; head with convex sides, strongly cordate posterior margin; in lateral profile promesonotum forming single convexity; scape with abundant erect setae, length of setae about one half maximum width of scape; mid and hind tibia with abundant erect setae, longest setae about one half maximum width of tibia; sides of head without erect setae; posterior margin of head with erect setae; pronotum and mesonotum with abundant long erect setae, somewhat sparser erect setae on dorsal face of propodeum; color light to dark brown, if somewhat bicolored gaster is darker then mesosoma.

Queen
Holotype: HLA 2.14, HW 2.13, SL 1.335, EL 0.518, OC 0.102, MTSC 30.

(n=10): HLA 2.00 (1.94–2.14), HW 2.00 (1.94–2.17), SL 1.31 (1.28–1.39), CI 100 (99–104), SI 66 (62–67).

Palpal formula 6,4; ocelli small; middle and hind tibia with prominent pectinate apical spur; dorsal surface of mandible with small piligerous puncta, setae in puncta short, subdecumbent, interspaces between puncta smooth and shiny on apical half of mandible, gradually becoming faintly microareolate at base; medial and lateral clypeal lobes at about same level; head broadly cordate with rounded sides; petiolar node tall, strongly compressed into thin scale at apex; posteroventral petiolar lobe evenly convex from front to back; scape with abundant 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 one third to one half maximum width of tibia (MTSC 20–30); sides of head without erect setae; posterior margin of head with abundant erect setae; pronotum with erect setae on posterior margin; mesoscutum, scutellum, and propodeum with abundant erect setae; petiolar node with rim of dense erect whitish pubescence, sparse longer setae, one pair extending above apex in profile, posterior border of sternal lobe of petiole with dense layer of long erect pubescence and several erect setae that are about twice as long as pubescence; gastral terga with sparse long erect setae; light orange brown coloration on clypeus, malar area, antennal fossa, and side of head, variable extent of infuscation on medial and posterior vertex.

Type Material
Holotype alate queen: Costa Rica, Prov. Limón, Hamburg Farm [10°15'N, 83°27'W], 50m, 11 Jul 1925 (F. Nevermann), specimen (pin) code JTLC000005642.

Paratypes: same data as holotype; 2 workers [JTLC000005642, USNM]; alate queen, worker, male JTLC000005643, ; alate queen, 2 workers JTLC000009416, ; 2 workers, 1 male JTLC000009415, ; 8 workers [JTLC000009412, JTLC000009413, JTLC000009414, USNM]; 3 workers JTLC000009405,.

Etymology
The name refers to this species being a southern version of the Mexican species A. sericea.

References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * De la Mora, A., C. J. Murnen, and S. M. Philpott. 2013. Local and landscape drivers of ant-communities in Neotropical coffee landscapes. Biodiversity and Conservation 22: 871-888.
 * Hajian-Forooshani, Z., I. S. Rivera Salinas, E. Jimenez-Soto, I. Perfecto, and J. Vandermeer, 2016. Impact of regionally distinct agroecosystem communities on the potential for autonomous control of the coffee leaf rust. Journal of Environmental Entomology 6: 1521-1526.
 * Jackson, D., J. Vandermeer, I. Perfecto, and S. M. Philpott. 2014. Population responses to environmental change in a tropical ant: the interaction of spatial and temporal dynamics. Plos One, 9: e97809.
 * Larsen, A., and S. M. Philpott. 2010. Twig-nesting ants: the hidden predators of the coffee berry borer in Chiapas, Mexico. Biotropica 42: 342-347.
 * Li, K., J. H. Vandermeer, and I. Perfecto. 2016. Disentangling endogenous versus exogenous pattern formation in spatial ecology: a case study of the ant Azteca sericeasur in southern Mexico. Royal Society Open Science 3: 160073.
 * 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: 1-63
 * Marin, L., D. Jackson, and I. Perfecto. 2015. A positive association between ants and spiders and potential mechanisms driving the pattern. Oikos 124: 1078-1088.
 * Philpott, S.M., P. Bichier, R. Rice, and R. Greenberg. 2007. Field testing ecological and economic benefits of coffee certification programs. Conservation Biology 21: 975-985.