Taylor (1965) captured a live colony on Barro Colorado Island, Panama, and published the following notes:
My Barro Colorado accession originally consisted of 22 workers, 7 queens (4 alate), 11 pupae (9 worker, 2 male), 2 pharate pupae and 6 larvae of various instars. These were collected from an old beetle gallery in a fairly sound, dry portion of a rotting branch about 30 cm. long and 8-10 cm. in diameter, lying on the floor of primary rainforest. The ants were in a single group occupying almost 3 cm. of the gallery, which was about 6-10 mm. in diameter. An aspirator device was used for collection, and it is presumed that the whole colony, excluding foragers, was taken. One of the queens was more worn than the others and appeared to be the 'mother-queen' of the colony. The specimens were immediately placed in a glass-topped plaster-of-Paris observation cell, in which they survived for six days until the death of the queen and the larvae disrupted their behaviour. A number of eggs were accumulated during this period, at least two of them being laid by the queen. One worker completed its development while under observation.
Various small soil arthropods including assorted Collembola, Symphyla, small immature spiders, larval and adult ants, Diptera, Coleoptera and termites at all stages were placed in the nest from time to time. None of these organisms were attacked or accepted as food; indeed, the ants usually retreated hurriedly with their brood when confronted by other animals.
The larvae and pharate pupae, still enclosed in larval cuticles, were not placed by the nurse workers on the nest floor, but were attached to the plaster walls or glass ceiling of the brood chamber by the peculiar terminal abdominal suspensory tubercles described above, so as to hang head downwards. Eggs and pupae were normally placed on the floor of the brood chamber, but under most conditions they too were attached to the nest ceiling, presumably being held there by the surface tension forces of the moisture film on the glass. Pupae were invariably placed with the frontal region of the head adherent to the ceiling, and the eggs were attached either directly to the ceiling, or to the bodies of larvae or pupae.
The workers were very active and 'excitable', being reminiscent of Leptogenys or Platythyrea in this regard. They ran quite rapidly and 'nervously' when disturbed and, even when settled, were constantly active, grooming themselves and their partners. The larvae were assiduously attended and were almost constantly being licked by one or more of the workers. The suspended brood was usually placed immediately above the main adult cluster, the nurse workers moving on to the ceiling to attend to the larvae.
Workers were not observed transporting their fellows, but the queen was carried about 5 cm. in the jaws of a worker on one occasion. She lay in a pupal posture and was held by the frontal part of the head, lying ventral side uppermost along the underside of the transporting worker. Pupae were always normally carried in this way, although they were sometimes dragged by the legs or antennae when being positioned by nurse workers. The larvae were always carried along the underside of transporting workers and were invariably gripped about the neck of the terminal abdominal suspensory tubercle. This mode of grasping the larvae appeared to facilitate their placement on the nest ceiling by the workers. The newly emerged workers are highly callow, and apparently take about 5 days to attain full coloration.
I know of only one collection of Probolomyrmex boliviensis from Costa Rica, with the following data:
Prov. Limon: Guapiles, 10¡13'N, 83¡47'W, palmito plantation, 28 Apr 1996 (coll. R. Matlock).
Costa Rica, Panama, Colombia, Peru, Bolivia (Agosti 1995).
Taxonomic history
Oliveira & Feitosa, 2019 10.11646/zootaxa.4614.1.3 PDF: 68 (w.q.).Senior synonym of Probolomyrmex angusticeps: Brown, 1975 PDF: 11.See also: Taylor, 1965d PDF: 361.Probolomyrmex boliviensis Mann , 1923, Psyche, Camb., Mass. 36: 16, fig. 2, [[ queen ]]. Type locality: Rurrenabaque, Bolivia. Holotype: United States National Museum (Type No. 25906) (examined).
Mann's unique holotype queen of P. boliviensis has the following dimensions: HL, 0.66 mm.; HW (behind eyes), 0.43 mm.; SL, 0.47 mm.; CI, 65; SI, 109; WL, 0.95 mm.; mesonotal width, 0.33 mm.; dorsal petiole width, 0.20 mm.; petiole height, 0.27 mm.; petiolar node length, 0.34 mm.; lateral petiolar index, 126. As perusal of the relevant figures will verify, P. boliviensis closely resembles the queen of the Panamanian P. angusticeps, and there is a possibility that these two forms are mere geographical variants of a single species. At present it does not seem advisable to upset their separate status, which can be clarified only by study of additional material.
The boliviensis holotype differs from her Panamanian counterparts in the following characters:
(1) Smaller size (HL, 0.66 mm. against 0.74 - 0.76 mm. in angusticeps), with relatively broad head (CI, 65 against 61 - 63) and node (petiolar node width, 0.61 times the mesonotum width against 0.55 - 0.57 times in angusticeps).
(2) Antennal scapes proportionately much shorter (SI, 109 as opposed to 130 - 132 in queens of angusticeps).
(3) Sculpturation similar in distribution and relative intensity on different parts of the body, but superficial punctures of head, mesosomal dorsum and node distinctly less clearly incised in boliviensis .
Mann reported the palpal formula as maxillary 3: labial 2. This observation was based on the undissected holotype, and only the visible segments were considered. After studying the specimen I believe that the true maxillary count is probably 4, as in other species of Probolomyrmex . The general proportions of the palpal segments are as described above for P. angusticeps .
Distribution. - Known only from the type locality, Bolivia: Rurrenabaque (W. M. Mann).
Biology. - The unique holotype was taken beneath a stone, near a small colony of Ponera .
boliviensis Mann 1923: 16. Holotype female, BOLIVIA , Beni , Rurrenabaque , W. M. Mann . USNMtype 25906 . Description of larva, pupa and biology: Taylor , 1965 : 348 - 9, 360 - 1 [checked] .
angusticeps M. R. Smith 1949: 39. Syntypes 2 workers, Panama, Barro Colorado Island, Zetek # 5272. Smithsonian type 58833 [checked]. Synonymy by Brown, 1975: 11 [see also note 22 in Brown, 1975: 57]. Synonymy confirmed.
FEMALE. HL 0.67 - 0.70, HW 0.45 - 0.5, SL 0.47 - 0.61, TL 0.98 - 1.06, CI 65 - 69, SI 105 - 123, Figures 1 - 2 (3 examined).
WORKER. HL 0.68 - 0.82, HW 0.42 - 0.47, SL 0.50 - 0.64, TL 0.96 - 1.25, CI 57 - 62, SI 119 - 136, Figures 3 - 4 (15 examined).
Material examined. 18 workers, 3 females, deposited in MCZ and USNM . PANAMA , Barro Colorado Island , Canal Zone , 21 June 1961 , R. W. & W. Taylor ; PANAMA , pipeline road, Gamboa , 1976 , Sclavings . COLOMBIA , Magdalena , Tayrona PK, Pueblito , 1 October 1976 , Berlese sample , leaf litter, C. Kugler . PERU , Madre de Dios , Cuzco Amazonico , 15 km NE of Puerto Maldonaldo , 200 m, Terra Firme forest, plot 1 U 15, rotten chunk of wood half buried in soil, 22 June 1989 , S. P. Cover & J. Tobin .
Comments. This is the largest of the South American species. It is easily diagnosed by the combination of its mesosoma size, the short scape and the very distinct sculpture. The synonymy could be confirmed through a series of workers and females. The biology of boliviensis is described in detail by Taylor (1965), but many questions such as nutritional base need to be answered. This species occurs in rainforests of northern South America, from Panama to Bolivia.
