Azteca

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 : 10-14

[[ Genus Azteca ]]

Key to queens (Costa Rica)

The queen of A. chartifex is unknown, but it will probably key to A. tonduzi .

1. Outer margin of hind tibia with abundant erect setae, MTSC usually> 20, if MTSC in the 10-20 range, CI> 95..............................................................................................................................................................2

- Outer margin of hind tibia with erect setae reduced to absent, MTSC <20, if MTSC in the 10-20 range, CI <80.......................................................................................................................................................11

2. Head subrectangular (Fig. 2, coeruleipennis , xanthochroa ), CI <90, obligate Cecropia inhabitant..........3

- Head with sides more rounded (e.g., Fig. 2, constructor ), CI> 90, nesting habits various........................4

3. Color dark brown to black, HW <1.55mm; head shape as in Fig. 2 ( coeruleipennis ); palpal formula 6,4.. ................................................................................................................................................ coeruleipennis

- Color orange, HW> 1.80mm; head shape as in Fig. 2 ( xanthochroa ); palpal formula 5,3...... xanthochroa

4. Color solid black throughout; mesosomal dorsum with dense brush of setae over entire surface; many setae on margin of vertex as long as distance between lateral ocelli (Fig. 2, constructor ); HW 1.4-1.8mm (Fig. 4A); palpal formula 5,3; obligate Cecropia inhabitant....................................................... constructor

- Color rarely solid black, usually red brown, or black with lighter yellow brown on variable extent of anterior and lateral face; mesosomal dorsum often with abundant setae but never a dense brush; setae on margin of vertex shorter than distance between lateral ocelli; HW various; palpal formula 6,4; not obligate Cecropia inhabitants....................................................................................................................................5

5. HW> 2.3mm; face usually uniformly colored light red brown to dark brown...........................................6

- HW <2.2mm; face with variable combination of black to lighter yellow brown (varies from almost entirely black with narrow region of lighter color at anterior margin of head capsule, to almost entirely yellow brown with patch of infuscation on posteromedian vertex)............................................................7

6. Antennae relatively long (SI> 58); ocelli large (OCW> 0.20mm); posterior sternal lobe of petiole shallow and evenly sloping to apex of posterior tergal lobe (Fig. 1E, 5); apex of petiolar node in lateral view flattened and scale-like (Fig. 5) ....................................................................................................... instabilis

- Antennae relatively shorter (SI <55); ocelli small (OCW <0.15mm); posterior sternal lobe of petiole more convex and shorter, meeting posterior tergal lobe before apex (Fig. 1D, 5); apex of petiolar node acute but not as strongly flattened, more bluntly rounded (Fig. 5) ....................................................... gnava

7. HW> 1.9mm (Fig. 4A); face extensively yellow brown with darker brown infuscation on vertex (Fig. 3) ....................................................................................................................................................... sericeasur

- HW <1.9mm; face coloration as above or more extensively dark brown to black .................................... 8

8. HW <1.58mm (Fig. 6A); head almost entirely black, with small band of lighter coloration on anterior head capsule (Fig. 3) ..................................................................................................................... flavigaster

- HW> 1.58mm; head coloration as above or with more extensive yellow coloration extending up sides of head and into antennal fossae ...................................................................................................................... 9

9. Sternal lobe of petiole with posterior margin forming a separate convexity that extends as far posteriorly as posterior tergal lobe, with a small notch or concavity between the sternal convexity and the tergal lobe (Fig. 1D, 5); head relatively short (Fig. 6A); forms ant gardens ........................................................... nigra

- Sternal lobe of petiole evenly curved to tergosternal suture, not forming separate convexity or notch, posterior tergal lobe extending further posteriorly than sternal lobe (Fig. 1E); head relatively longer (Fig. 6A: velox , quadraticeps ); nests in live or dead stems with variable construction of small carton shelters, but not forming large conspicuous ant gardens ............................................................................................... 10

10. Head relatively shorter and more cordate, sides more strongly narrowing anteriorly (Fig. 3, 6A,B) .. velox - Head relatively longer and more quadrate, sides less strongly narrowing anteriorly (Fig. 3, 6A,B) ............ .................................................................................................................................................. quadraticeps

11. Meso- and metatibial spurs absent; anterior margin of clypeus strongly convex, median lobe extending anterad to lateral lobes (HLB/HLA> 1.04); entire body smooth and shiny, highly polished ( aurita group) ................................................................................................................................................................... 12

- Meso- and metatibia with distinct pectinate spurs; anterior margin of clypeus weakly convex, subparallel with lateral lobes (HLB/HLA <1.01); body surface duller, not shiny ....................................................... 14

12. Color yellow-orange; posterolateral margins of vertex forming pronounced triangular lobes (Fig. 2); CI> 85 (Fig. 4A) ...................................................................................................................................... pilosula

- Color brown; posterolateral margins of vertex not forming pronounced triangular lobes; CI <80 .......... 13

13. HW <0.65mm (Fig. 4A); sides of head relatively more rounded and converging toward posterolateral lobes of vertex (Fig. 9); outer surface of metatibia with abundant suberect pubescence and numerous, regularly spaced, short, erect setae ...................................................................................................... nanogyna

- HW> 1.00mm (Fig. 4A); sides of head subparallel, not converging toward posterolateral lobes of vertex (Fig. 2); outer surface of metatibia with pubescence relatively short, sparse, appressed, and inconspicuous; outer surface of metatibia lacking erect setae or with a few, irregularly spaced, short setae near the base ................................................................................................................................................. schimperi

14. Head relatively short and broad (CI> 78) ................................................................................................. 15

- Head relatively long and narrow, subrectangular (CI <78) ...................................................................... 18

15. Petiolar node strongly flattened, scale-like (Fig. 5); head short and broad (CI> 100, Fig. 4A) ........ tonduzi

- Petiolar node not strongly flattened, apex usually bluntly rounded; head relatively longer and thinner (CI <90) ........................................................................................................................................................... 16

16. HW> 1.53mm (Fig. 4A); dorsal surface of mandible evenly covered with abundant large piligerous puncta (Fig. 1G), setae arising from puncta erect, about as long as width of mandibular teeth; builds carton galleries on tree trunks, not a Cecropia specialist .......................................................................... forelii

- HW <1.45; much of dorsal surface of mandible with sparse, small puncta bearing setae that are reduced to short remnants, no longer than width of puncta (Fig. 1F), puncta with longer setae restricted to apex and near masticatory margin; Cecropia specialists..........................................................................................17

17. Fourth abdominal tergum with <6 erect setae, exclusive of posterior row; dorsal surface of head, when viewed in profile, with setae occurring in three clusters separated by distinct gaps, one cluster on and just above the clypeus, one around the ocelli (these may be entirely absent), and one on the upper vertex; scape relatively short (SI 45-49, Fig. 6C); color usually black............................................................ alfari

- Fourth abdominal tergum with> 10 erect setae (rarely fewer), exclusive of posterior row; dorsal surface of head, when viewed in profile, often with setae bridging the gap between the ocellar region and the upper vertex, and often with setae extending up from the clypeus almost to the ocellar region; scape relatively longer (SI 49-54, Fig. 6C); color black to lighter red brown............................................... ovaticeps

18. Color largely orange; HW> 1.2mm (Fig. 4A)...................................................................................... beltii

- Color largely or entirely black; HW <1.2mm...........................................................................................19

19. Mandible with even covering of coarse, piligerous puncta; mandible surface appearing bristly..............20

- Mandible with row of piligerous puncta along masticatory margin, but large puncta sparse to absent on mandible surface proximal to this row, and with at most four puncta bearing setae.................................21

20. Scape relatively short (SI 39-43).......................................................................................................... brevis

- Scape longer (SI 50-52)................................................................................................................. nigricans

21. Head strongly rectangular, with flat sides and posterolateral lobes of vertex relatively angular; head relatively longer and narrower (SI <63, Fig. 4B)...........................................................................................22

- Head less rectangular, with sides slightly convex, and lateral margin of vertex more broadly rounded; head relatively shorter and wider (SI> 63, Fig. 4B).......................................................................... pittieri

22. Petiolar node low, anterior face of petiole flat (Fig. 5); metatibia with few erect setae (MTSC <5); propodeum with sparse short setae concentrated posterior to spiracle; mandible lacking large puncta proximal to masticatory margin; size relatively large (HW> 0.92mm, Fig. 4B)........................................... oecocordia

- Petiolar node higher, anterior face somewhat concave (Fig. 5); metatibia with relatively more setae (MTSC 10-20); propodeum with setae sparse or abundant; mandible with about 5 large puncta proximal to masticatory margin; size relatively smaller (HW <0.93mm, Fig. 4B)...................................... longiceps

Key to workers (Costa Rica)

Identifying Azteca species from the morphological traits of individual workers is difficult. Colonies show strong size variation among workers (Wheeler 1986), and the size of the largest workers increases as colonies mature. The larger a worker is, the more queen-like it is and the more differentiable from other species. The following key is most likely to work when a series from a mature colony is available, so that the largest workers can be selected for examination. When size ranges are given in the key, they refer to these larger workers. The workers of A. nanogyna and A. quadraticeps are unknown.

1. Middle and hind tibia lacking apical spur; anterior margin of clypeus strongly convex, median lobe protruding further than lateral lobes (HLB/HLA> 1.04), Fig. 3: pilosula and schimperi ); palpal formula 4,3 ( aurita group)...............................................................................................................................................2

- Middle and hind tibia with distinct, pectinate apical spur; median lobe of clypeus not protruding, subparallel with lateral clypeal lobes (HLB/HLA <1.01); palpal formula 5,3 or 6,4...........................................3

2. Dorsal surface of mandible smooth, not striate; posterolateral margin of vertex evenly rounded (Fig. 3); sternal lobe of petiole with sharp, longitudinal carina.................................................................... schimperi

- Dorsal surface of mandible striate; posterolateral margin of vertex subangular (Fig. 3); sternal lobe of petiole longitudinally tectiform but not carinate................................................................................... pilosula

3. Outer surface of hind tibia completely devoid of erect setae, rarely with 1 or 2 short setae on largest workers; palpal formula 5,3 ................................................................................................................................. 4

- Outer surface of hind tibia with 5 or more erect setae (these may be very short, less than a quarter of tibial width, and difficult to see); palpal formula 5,3 or 6,4.. ............................................................................... 8

4. Promesonotum strongly produced, bulging, dropping steeply to flat dorsal face of propodeum (Fig. 7) ..... ......................................................................................................................................................... chartifex

- Promesonotum less strongly produced, posterior mesonotum more shallowly sloping and meeting dorsal face of propodeum at more obtuse angle ..................................................................................................... 5

5. Dorsal surface of mandible largely smooth with small non-setose puncta, setigerous puncta restricted to masticatory margin (Fig. 1F) ....................................................................................................................... 6

- Dorsal surface of mandible evenly covered with large setigerous puncta (Fig. 1G) ................................... 7

6. Dorsum of mesosoma with a relatively "clean" look, with relatively few erect setae, these of relatively uniform length (MNSC 2-17, median 8, Fig. 7) .................................................................................. alfari

- Dorsum of mesosoma more "scruffy," with more setae, and these of irregular length (MNSC> 10, median about 20, Fig. 7) .............................................................................................................................. ovaticeps

7. Dorsal face of propodeum with moderately abundant erect setae; SI> 50; HW of larger workers often> 1.1mm; basal half or more of mandible microalveolate, dull ............................................................... forelii

- Dorsal face of propodeum devoid of erect setae; SI <50; HW of larger workers usually <1.0mm; entire mandible generally smooth and shiny on interspaces between puncta ................................................. brevis

8. Palpal formula 6,4; color yellow; dorsal face of propodeum and metanotal groove together form a single flat "shelf" that abruptly meets rising posterior mesonotum (Fig. 7); obligate Cecropia inhabitant ............. ................................................................................................................................................ coeruleipennis

- Palpal formula 5,3 or 6,4; color various; dorsal face of propodeum and mesonotum forming two convexities that meet at impressed metanotal groove (e.g., Fig. 7, sericeasur worker); nesting habits various ..... 9

9. Palpal formula 5,3; mostly species (with the exception of A. tonduzi ) nesting in myrmecophytes ( Cecropia , Cordia , Triplaris ) or narrow-gauge live stems of various plant species, with foraging restricted to the hostplant stem interiors or surfaces ........................................................................................................... 10

- Palpal formula 6,4; species nesting in large plant cavities or ant gardens, with conspicuous and generalized surface foragers .................................................................................................................................. 17

10. Head relatively broad, CI> 86 (Fig. 6D); obligate Cecropia inhabitants or nesting in dead stems .......... 11

- Head relatively narrow, CI <90 (Fig. 6D); inhabitants of live stems but not obligate Cecropia specialists ................................................................................................................................................................... 13

11. Setae on metatibia sparse and short, MTSC 10-20, length of setae one fourth to one third maximum width of tibia; HW of larger workers <0.91mm (Fig. 6D); nests in dead stems often augmented with carton nests .................................................................................................................................................... tonduzi

- Setae on metatibia abundant and longer, MTSC> 20, length of setae one half or more maximum width of tibia; HW of larger workers> 1.10mm (Fig. 6D); obligate inhabitants of Cecropia ................................ 12

12. Petiole in profile with node more massive than sternal lobe, perpendicular distance from tergosternal suture to apex of node greater than or equal to distance to ventral margin of sternal lobe (Fig. 7); face with mottled coloration, light brown to orange with variable extent of medial infuscation (Fig. 3).... xanthochroa

- Petiole in profile with node less massive than sternal lobe, perpendicular distance from tergosternal suture to apex of node less than distance to ventral margin of sternal lobe (Fig. 7); face uniformly brown (Fig. 3) ..................................................................................................................................................... constructor

13. Most of dorsal surface of mandible covered with large piligerous puncta, mandibles appearing bristly (Fig. 1G); nesting in live stems of multiple plant species, not obligate inhabitant of Cordia or Triplaris ... ........................................................................................................................................................ nigricans

- Dorsal surface of mandible with large piligerous puncta, if present, restricted to masticatory margin and apex, mandibles not appearing bristly (Fig. 1F); nesting habits various, including obligate inhabitants of Cordia and Triplaris ..................................................................................................................................14

14. Setae on metatibia few and short, MTSC usually about 5, setae about as long as one quarter width of tibia; propodeum with cluster of about 4 setae where dorsal face rounds into posterior face, 0-4 setae anterior of this cluster on dorsal face, these setae short, 1-2 times width of propodeal spiracle; largest workers with HW> 1.0mm (Fig. 6D).............................................................................................................................15

- Setae on metatibia more abundant and longer, MTSC 8-17, setae about as long as half width of tibia; dorsal face of propodeum with 4 or more setae, these setae long,> 4 times width of propodeal spiracle; largest workers with HW <1.0mm (Fig. 6D)..................................................................................................16

15. Face of largest workers yellow; dorsal surface of mandible with interspaces between puncta largely smooth and shining, at most basal third of mandible shagreened; posterior margin of sternal lobe of petiole with a layer of dense, short, pubescence-like pilosity and 2-4 longer setae; opportunistic inhabitant of multiple ant plants and live stems of non-myrmecophytes................................................................... beltii

- Face of largest workers brown; dorsal surface of mandible with interspaces between puncta shagreened on basal half or more; posterior margin of sternal lobe of petiole with cluster of erect setae of even length; obligate inhabitant of Cordia alliodora ....................................................................................... oecocordia

16. Head relatively broader (CI 78-91, Fig. 6D); obligate inhabitant of Cordia alliodora (or understory Lauraceae, see under A. pittieri )............................................................................................................... pittieri

- Head relatively narrower (CI 73-81, Fig. 6D); obligate inhabitant of Triplaris melaenodendron ............... ........................................................................................................................................................ longiceps

17. Mandibles opaque, densely microalveolate/punctate, substriate; posteroventral margin of petiole with abundant long coarse setae, shorter pubescence layer much less conspicuous than long setae (Fig. 7); majors very large (HW up to 2.2mm); nests in hollow trunks of large, live trees, with nest entrance a fissure at the base of the tree ................................................................................................................ instabilis

- Mandibles shiny to weakly sculptured; largest workers typically smaller, HW <1.8mm; nesting habits various (the workers of the following species are highly variable and I have not been able to discover diagnostic characters that always differentiate them; the following key couplets reflect average differences among species, but I have examined many worker series in this complex that I could not place).... 18

18. Gastral dorsum bright yellow, sharply contrasting with dark brown petiole and mesosoma; measurements as in Figs. 6E,F.............................................................................................................................. flavigaster

- Gastral dorsum dark brown, or, if light yellow brown, petiole and mesosoma are lighter brown as well, gastral color not sharply contrasting with mesosoma color.......................................................................19

19. Head relatively broad (Fig. 3, 6E, CI 101-109); scape relatively short (Fig. 6F, SI 70-85); face usually uniformly dark brown (lighter orange brown in one series); setae on posterior margin of vertex usually long, subequal in length to eye length; forms ant gardens................................................................... gnava

- Head relatively narrower; scape relatively longer; face color various but often a mixture of light and dark brown; setae on vertex margin usually shorter than eye length; nesting habits various............................20

20. Largest workers with HW usually> 1.2mm; general body coloration often light orange brown; head shape often strongly cordate (Fig. 3)....................................................................................................... sericeasur

- Largest workers with HW usually <1.2mm; general coloration often dark brown with light orange brown restricted to anterior and lateral portions of head; head shape often less strongly cordate (Fig. 3: velox and nigra ).........................................................................................................................................................21

21. Scape relatively short (Fig. 6F, SI 78-89); nests in plant cavities......................................................... velox

- Scape relatively longer (Fig. 6F, SI 84-105); nests in ant gardens....................................................... nigra