Camponotus mirabilis

Strict nocturnality in both C. mirabilis and Camponotus longipilis contrasts with diurnality in other bamboo specialists. Established colonies occupy multiple culms of Guadua bamboo after workers chew entrances in young stems prior to lignification. Foundresses of C. mirabilis appear to initiate their colonies by invading Camponotus longipilis nests and taking over established coccid populations, a major source of food (honeydew).

Identification
A member of the subgenus Myrmostenus.

Mackay (1997) - This is the most common species in the subgenus, and is also easily differentiated from all others. The head is greatly elongated and noticeably widened anteriorly. The occipital corners are strongly angulate as seen in full face view. The clypeus is nearly flat, with little evidence of a raised region in the area of the clypeal carina. All of the surfaces, including the dorsum of the head, are strongly polished.

This species is at the other extreme from Camponotus leptocephalus in terms of its morphology. The head is startling in view, greatly elongated and slender. The ventral surface of the head lacks erect hairs. The entire surface is shiny. The occipital angles are well differentiated from the remainder of the head.

Distribution based on Regional Taxon Lists
Neotropical Region: Bolivia, Brazil, Peru.

Biology
Davidson et al. 2006 - Most inhabited bamboo culms contained no queen, and we never observed more than one queen per patch of culms. Consistent with polydomy and monogyny, nocturnal columns of workers regularly transported brood, each other, and coccids among neighboring live culms; winged females occasionally commuted alongside nestmates.

Workers from established C. mirabilis colonies were observed to cut entrances at bases of new internodes in unlignified walls of young culms (<0.5 m high). As culm internodes elongated, initially circular entrances grew into linear holes, narrower distally than basally. Despite many nocturnal and diurnal visits to C. mirabilis nests, we never noted workers opening entrances in woody stem walls of older culms. Nevertheless, they apparently do cut openings in internodal septa, possibly before these harden.



Inside culms, brood is supported on numerous vertically stacked carton shelves (Fig. 1a). So distributed, larvae are positioned near honeydew-producing coccids (Hemiptera: Coccoidea: Coccidae) populating internal internode walls throughout their lengths. Progressively younger (smaller) coccids occur in higher (newer) internodes.

Supplemented by occasional arthropod prey, coccid honeydew constitutes an important source of larval and worker nutrition. Nocturnal activities included foraging for litter arthropods or (more commonly) wood fiber from decaying logs, commuting among nest culms, and transporting of brood or coccids among culms. Most major workers remained near culm bases, protecting nests, e.g., from Neivamyrmex army ants, which they bisected with their mandibles. Majors also helped to capture large prey (Coleoptera, Lepidoptera [moths] and Diplopoda), and all worker castes sprayed formic acid to subdue and kill prey. Diurnally, agitation of culms induced C. mirabilis workers to boil aggressively from stems and attack their assailant.

C. mirabilis is distinctive among bamboo ants in foraging aggressively for prey in the leaf litter (prior to seasonal flooding). This trait may explain restriction of C. mirabilis colonies to lower culms.

Workers were never observed to actively transport water from occupied culms, an in Tetraponera attenuata. Instead, nest modifications led to passive “self-bailing”. Rather than accumulating inside, water added to higher entrances drained rapidly from lowest entrances, most of them basal in internodes.

After frequent damage to nest stems by Cebus monkeys, C. mirabilis colonies regularly abandon their stems and live coccids. (Davidson et al. 2006)

Nomenclature

 *  mirabilis. Camponotus mirabilis Emery, 1903: 80, fig. 15 (q.) PERU. Combination in C. (Myrmomalis): Forel, 1914a: 271; in C. (Myrmostenus): Emery, 1920b: 260. See also: Mackay, 1997: 201.

Queen
Mackay (1997) - HL 4.18-4.70, HW 1.82-1.88, SL 2.08-2.24, EL 0.66-0.70, clypeal length 1.19- 1.28, clypeal width 0.98-1.08. Indices: SI 48-50, CI 40-44, clypea1 index 82-84.

Mandible with apical and subapical teeth large, well defined, at least 4 additional teeth defined to various degrees; clypeus weakly convex with little evidence of clypeal carina as slightly raised strip; clypeal border convex and rounded; scape short and not reaching posterior border of head; head more than twice as long as wide, noticeably widened near mandibles; vertex strongly concave, with occipital corners strongly angulate; maxillary palps very short, barely extending past buccal region; labial palps nearly as long as maxillary palps; propodeum with descending face about half length of basal face; petiole with strongly convex anterior face, nearly flat posterior face, thicker and less in height than in the other species.

Hairs erect, long, coarse and sparse on dorsum of head, pronotum, scutum and scutellum, propodeum, node of petiole and gaster; decumbent pubescence very weak and sparse on most surfaces.

Sculpture weak, shiny and polished on most surfaces.

Color medium brown, head, mandibles and scape somewhat darker, gaster with yellow blotches on both sides of anterior section of terga.

Type Material
Mackay (1997) - Lectotype queen [here designated], Vilcanota, Peru, Stdg; Camponotus mirabilis n. sp. [seen]; Marcapata, Peru; 2 paralectotypes [here designated], #21592 ( 2 queens. third female with same numbers and labels is C. longipilis).