Probolomyrmex boliviensis Mann

Taylor, R. W., 1965, A monographic revision of the rare tropicopolitan ant genus Probolomyrmex Mayr (Hymenoptera: Formicidae)., Transactions of the Royal Entomological Society of London 117, pp. 345-365 : 361-363

Probolomyrmex boliviensis Mann (figs. 32, 33)

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 .