Camponotus enigmaticus

The type series was collected nesting in a twig in tropical cloud forest. Brood, but no sexuals (nor the nest gyne) were found in the next. Despite searching twigs over a four-day period, no additional nests or specimens were found. (Mackay et al. 2004)

Identification
Mackay et al. (2004) - The major worker is a black ant, with much of the head reddish brown. Most of the hairs on the anterior half of the head are blunt-tipped, or spatulate, and short (0.02 - 0.05 mm). The anterior half of the head is weakly, obliquely truncate, and the scapes have several, erect hairs. The pronotal shoulder is swollen, and nearly forms a carina, the propodeum is slightly angulate between the two faces. The subpetiolar process is unusual for the genus Camponotus, in that it forms a swollen, angulate projection. Appressed pubescence is sparse on most surfaces, except for the dorsum of the gaster, where the erect hairs are fine and abundant, with individual hairs overlapping other adjacent hairs, and silver in color.

The intermediate major is similar to the largest major, except the hairs on the anterior half of the head are longer (0.05 mm - 0 .1 mm) and blunt-tipped, or only weakly spatulate. The antennal scape extends about 1/3 the length past the posterior lateral corner, and only the anterior 2/3 of the head is reddish brown. The propodeum is more angulate between the faces, and the subpetiolar process more rounded.

The minor workers do not resemble the major worker. The sides of the head are nearly straight, and only slightly narrowed anteriorly. The hairs on the head are at most blunt-tipped, many are sharp-tipped. The scape extends nearly 1/2 length past the posterior lateral corner, and only the anterior edges of the cheeks are yellowish brown. The pronotal shoulder is formed into a carina, and the propodeum is definitely angulate between the faces. The subpetiolar process is swollen as in the major worker, but is more blunt and rounded.

This species is a member of the subgenus Hypercolobopsis. It is similar to the other species in this subgenus in having blunt-tipped, or spatulate hairs on much of the anterior half of the head (present in most of the species), and in having numerous, erect hairs on the antennal scapes. The head is somewhat obliquely truncate. The antennal condyles are small, and the diameter of scape is narrow as in other species of Hypercolobopsis . The frontal carinae are widely spaced, and the anterior femur is only slightly swollen. It can be easily separated from the other species in this subgenus as the clypeus is not as strongly narrowed posteriorly. The truncated portion of the head is less flattened than other members of this subgenus.

It can be separated from Camponotus paradoxus and Camponotus coptobregma of subgenus Hypercolobopsis, as the side of the head is not separated from the truncated portion of the head by a carina, but by a simple bend. The clypeus has many tiny, spatulate erect hairs, which distinguishes it from Camponotus divergens, Camponotus ulcerosus, and Camponotus frontalis, which we also consider to be members of Hypercolobopsis. The convex surface of the clypeus separates it from Camponotus coriolanus, which has a flattened clypeus. It also shows similarities with the subgenus Pseudocolobopsis, especially Camponotus tonduzi. It can be easily separated by the numerous, spatulate hairs on the anterior half of the head of the major, which are completely lacking in C. tonduzi . The clypeal carina in C. tonduzi is sharp and well-developed, the clypeus of C. enigmaticus  is completely flat and lacks the clypeal carina. The gaster of C. enigmaticus  is covered with dense, fine, appressed hairs, whereas the gaster of C. tonduzi  has only a few scattered appressed hairs.

Distribution
Known only from the type locality in the state of Matagalpa, Nicaragua.

Distribution based on Regional Taxon Lists
Neotropical Region: Nicaragua.

Nomenclature

 * . Camponotus enigmaticus Mackay, Mackay & Mackay, 2004: 460, figs. 1-9 (s.w.) NICARAGUA.

Worker
Major. HL 1.82, HW 1.68, SL 1.26, EL0.41, CL0.70, CW0.63, WL 1.96, FFL 1.20, FFW 0.41. Indices: CI 92, SI 69, CLI 89, FFI 34.

Mandible apparently with 5 teeth (closed); anterior border of clypeus nearly straight, carina absent, sides of clypeus nearly straight, diverging anteriorly, region anterior to tentorial pits depressed; sides of head broadly rounded, slightly narrowed anteriorly, posterior border broadly rounded; frontal carinae widely spaced; eyes nearly reach sides of head; scape extends slightly more than first funicular segment past posterior lateral corner; dorsum of mesosoma weakly convex; pronotum slightly swollen at shoulder; propodeum slightly angulate between two faces of equal length, spiracle circular; petiole moderately thickened as seen in profile, subpetiolar process angulate.

Erect hairs abundant on head, hairs on clypeus spatulate, short (0.02 - 0 .05 mm), hairs on cheeks and malar area similar those between frontal carinae, and remainder of sides of head, blunt-tipped, hairs along posterior margin blunt-tipped or sharp, scape with several, erect hairs, including hairs at apex, dorsum of mesosoma, dorsum of petiole, and all surfaces of gaster, with sharp-tipped hairs, hairs on tibiae abundant, suberect, appressed pubescence sparse on head, mesosoma, fine, dense, and abundant on gaster.

Head densely, evenly punctate, dull, dorsum of mesosoma punctate, side of pronotum finely coriaceous, remainder of side of mesosoma punctate, with punctures in poorly defined rows, petiole coriaceous, dorsum of gaster very finely punctate, dull.

Most of head, antennae, mandibles red, posterior edge of head, mesosoma, petiole, and gaster black, legs dark brown, much of coxae and trochanters medium brown.

Intermediate major. HL 1.60, HW 1.48, SL 1.34, EL 0.40, CL 0.61, CW 0.60, WL 1.98, FFL 1.22, FFW 0.39. Indices: CI 93, SI 84, CLI 98, FFI 32.

Similar to major worker, differing in that scapes are longer, extending about 1/3 the length past posterior lateral corner, hairs on clypeus and cheek blunt-tipped, not spatulate, or very weakly spatulate. Region between faces of propodeum more angulate, subpetiolar process more rounded. Only anterior 2/3 red, posterior 1/3 of head black.

Minor. HL 1.24-1.26, HW 1.00-1.04, SL 1.38-1.40, EL 0.35-0.36, CL 0.40-0.41, CW 0.56-0.58, WL 1.66-1.70, FFL 1.12-1.16, FFW 0.34-0.35. Indices: CI 81-83, SI 110-113, CLI 136-144, FFI 30.

Mandible apparently with 6 teeth (all closed); anterior border of clypeus nearly straight, carina poorly developed, sides of clypeus nearly straight, diverging anteriorly, sides of head nearly straight, converging anteriorly, posterior border broadly rounded; frontal carinae widely spaced: eyes extending slightly past sides of head; scape extending about ½ length past posterior lateral corner; dorsum of mesosoma broadly rounded; pronotal shoulder forming carina; region between 2 propodeal faces of equal length angulate; petiole moderately thickened as seen in profile, apex sharp, forming carina which extends on side of petiole, subpetiolar process rounded, but swollen.

Dorsum of head with abundant, erect hairs, sharp-tipped, extending from cheek and malar area, along sides of head, and across posterior border, abundant between frontal carinae, on ventral surface of head, dorsum of mesosoma, where some hairs are slightly twisted (especially on propodeum), present on dorsum of petiole, and all surfaces of gaster, hairs on tibiae suberect; appressed hairs scattered on dorsum of head, relatively long (0.05-0.08 mm in length), similar hairs present on dorsum of mesosoma, hairs on dorsum of gaster finer, dense, with individual hairs touching adjacent hairs.

Head finely, but densely punctate, weakly shining, dorsum of mesosoma similar, but with slightly coarser punctures, sides of pronotum coriaceous, moderately shining, remainder of mesosoma punctate as dorsum, petiole coriaceous, dorsum of gaster finely punctate, weakly shining.

Black, anterior edges of cheeks yellowish-brown, mandibles, antennae reddish brown.

Type Material
Holotype major worker, one paratype major worker , 4 paratype minor workers (CWEM, MCZC), Nicaragua, Matagalpa, Hotel Selva Negra, 9-vii-2003, l285m, Wm., E. & M. Mackay# 20114;

Etymology
From Latin, aenigma, meaning riddle or mystery, referring to the uncertain relationship of this species to the remainder of the genus.