Camponotus polymorphicus

This black carpenter ant is known from higher altitudes in the Andes Mountains of Colombia. This species is unusual in that it is extremely variable in size. Workers are present as majors, intermediates and minors. The females and males are dimorphic in size. It is one of the few tropical species found at high elevations, the only other relatively common tropical Camponotus at such elevations is Camponotus nitens, which is much smaller and has a heart-shaped head. (Mackay et al. 2002)

Identification
Mackay et al. (2002) - This high altitude, shiny black Camponotus is unlikely to be confused with any other species. They head of the major is elongate, with the sides nearly straight, converging anteriorly. The clypeal carina is indented about midway along the length. The metanotum is well defined, and the metanotal suture is depressed below the level of the remainder of the mesosoma. The cheeks, malar areas, and the entire surface of the clypeus are covered with bristly, golden, erect hairs. The scape is without erect hairs, except at the apex. It is polymorphic, with many sizes of workers. We have divided workers into 3 size classes, although there may actually be four, found in colonies of all ages (Lopez-Castro et al. 2002). The males and females are both dimorphic in size.

This is the most polymorphic species of Camponotus in the Neotropics. The workers can be arbitrarily divided into majors, intermediate workers, and minors, although there may actually be 4 separate size classes. The females are dimorphic, with the head length of the smaller size class ranging from 1.70 - 1.90 and head widths of 1.50 - 1.65; the larger size class has HL of 2.22 - 2.35, with a head width 2.0. The males are also dimorphic, with the smallest size class having head lengths ranging from 1.70 - 1.90 mm, with head widths of 1.5 - 1.65; the largest size class has head lengths from 2.22 - 2.35, head width of 2.0.

Camptonotus polymorphicus could be confused with Camponotus bonariensis (which are also shiny and polished), but can be separated by color (C. polymorphicus is black, C. bonariensis is brown) and by the shape of the head (elongate, that of C. bonariensis nearly as wide as long). The only other species of high elevation Camponotus in Colombia is Camponotus nitens, which are much smaller, have a heart-shaped head, and are brown. Therefore this new species can be easily separated from all other Neotropical species of Camponotus.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia.

Biology
Mackay et al. (2002) - The ant was studied in Andes Mountains between 2600 and 3300 meters in elevation. The habitat comprises high Andean forest to paramo vegetation. This species nests in the soil, rotten logs and in living and dead “frailejon” paramo plants (Asteraceae: Espeletia grandiflora, Espeletiopsis corymbosa and E. bogotensis). This is an unusual habitat for tropical ants, and few species are found higher than 2000 meters. This makes C. polymorphicus an especially interesting ant. A mature colony has more than 3700 workers. Apparently, the young colonies inhabit living and dead frailejones and the older colonies become subterranean (Lopez-Castro, 2001). The nests have a grouped distribution, and are polydomous, and they establish new nests by budding.

Worker
Minor

Nomenclature

 * . Camponotus (Tanaemyrmex) polymorphicus Mackay, López-Castro & Fernández, 2002: 422, figs. 1-6 (w.q.m.) COLOMBIA.
 * Status as species: Mackay & Mackay, 2019: 766.

Worker


Major. HL 2.42, HW 2.26, SL 2.45, EL 0.56, CL 0 .85, CW 1.00, WL 3.10, FFL 2.16, FFW 0.55. Indices: CI 93, SI 101, CLI 118, FFI 25.

Mandible with 6 teeth; anterior border of clypeus concave, clypeal carina poorly defined, distinctly indented with outline broken about ½ length; head narrowed anteriorly, sides of head nearly straight, posterior border weakly concave; eyes failing to reach sides of head by about ¼ minimum diameter; scape extending about 2 funicular segments past posterior lateral corner; maxillary palps extending 3 segments past posterior border of buccal cavity; mesosoma arched throughout, weakly depressed at promesonotal suture; metanotum well-defined, metanotal suture well depressed below dorsal outline of mesosoma; dorsal face of propodeum slightly longer than posterior face, spiracle oval-shaped; petiole narrow as seen in profile, apex pointed as seen from front.

Erect hairs abundant on most surfaces, including clypeus, cheeks, malar area, area between frontal carinae, mesosoma, and gaster, hairs on tibiae appressed; appressed pubescence sparse, few hairs on dorsum of head, dorsum of mesosoma, and dorsum of gaster.

Moderately to strongly shining, head with scattered circular punctures intermixed with coarse elongate punctures, mesosoma coriaceous, gaster very finely, transversely striolate, smooth and predominantly glossy.

Black.

Intermediate. HL 1.82 - 1.98, HW 1.44 - 1.68, SL 2.00 - 2.26, EL 0.49 - 0.53, CL 0.63 - 0.70, CW 0.80 - 0.90, WL 2.48- 2.74, F'FL 1.72 - 1.88, FFW 0.40 - 0.45. Indices: Cl 79 - 85, SI 110 - 114, CLI 128 - 129, FFI 23 - 24.

Mandible with 6 teeth, anterior border of clypeus concave, clypeal carina moderately developed, and indented as in major worker; sides of head straight, parallel, posterior border convex; eyes nearly reach sides of head; scape extends about ½ length past posterior lateral corner; mesosoma and petiole as in major worker. Pilosity, sculpture, and color as in major worker.

Minor. HL 1.30 - 1.64, HW 1.06 - 1.64, SL 1.42 - 1.56, EL 0.34 - 0.40, CL 0.41 - 0.58, CW 0.60 - 0.69, WL 1.72 - 2.06. FFL 1.06 - 1.24, FFW 0.28 - 0.35. Indices: CI 82 - 83, SI 95 – 109, CLI 120 – 145, FFI 27 - 28.

Mandible with 6 teeth; anterior border of clypeus convex; head slightly narrowed anteriorly; eyes extend past sides of head; scape extends about ½ length past posterior lateral corner; mesosoma rounded, metanotum not defined, sutures little depressed below level of mesosoma; pilosity, sculpture, and color as in major worker.

Queen
HL 1.80 - 2.28, HW 1.56 - 1.96, SL 1.64- 2.44, EL 0.51- 0.68, CL 0.64 - 0.80, CW 0.76 - 0.96, WL 3.40 - 4.06, FFL 1.52 - 2.08, FFW 0.40 - 0.53. Indices: CI 86 – 87, SI 91 - 107, CLI 120, FFI 26.

Mandible with 6 teeth; anterior border of clypeus concave, carina moderately defined; head widened anteriorly, sides nearly straight, posterior border convex; eyes extend past sides of the head; scape extends nearly ½ length past posterior lateral border; petiole narrow as seen in profile, apex nearly flat as seen from front.

Golden, erect hairs present across disk of clypeus, malar area, cheek, region between frontal carinae, mesosoma. dorsum of petiole, scattered across dorsum of gaster. Sculpture and color as in major worker.

Male
HL 1.06 - 1.44, HW 0.94 - 1.24, SL 1.78 - 1.86, EL 0.41 - 0.53, CL 0.33 - 0.42, CW 0.45 - 0.64, WL 2.28 - 3.42, FFL 1.54 - 2.28, FFW 0.23 - 0.35. Indices: CJ 86 - 89, SI 129 - 168, CLI 138 - 152, FFI 15.

Males are dimorphic (slightly over 5 mm and s lightly over 8 mm total length), black, with abundant hair on the clypeus, cheek, malar area, posterior border of head, mesosoma, petiole, and gaster. The hairs on the tibiae are appressed to decumbent. The frontal carina is poorly marked.

Type Material
Holotype major worker, 4 paratype intermediate workers, 24 paratype minor workers, 3 paratype females (2 small, 1 larger), and 9 (8 small and l large) paratype males, Colombia, Cundinamarca. Municipio Choconta. 5°1 'N 73°42'W, 2700 - 2800 m, viii-2000, C. Lopez-C. (,, IAVH, , , , ).

Material examined. Type series. Additional specimens were collected in the Municipio de Guasca, Cundinamarca, at elevations above 2600 m.

Etymology
From Greek, polys for many, and morphe for form, indicating the polymorphic workers, and dimorphic females and males of this unusual, high altitude species.