Probolomyrmex salomonis, Taylor, R. W., 1965

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 : 358

Probolomyrmex salomonis sp. n. (figs. 20, 21)

Holotype worker

HL, 0.59 mm.; HW, 0.38 mm.; SL, 0.37 mm.; CI, 64; SI, 97; WL, 0.79 mm.; PW, 0.30 mm.; dorsal petiole width, 0.17 mm; petiolar node index, 57; petiolar height, 0.28 mm.; petiolar node length, 0.26 mm.; lateral petiolar index, 93. General form as shown in the figures. Habitus similar to that of P. dammermani and P. greavesi . Head narrower than in these species, with occipital border moderately concave. Scapes relatively as long as in dammermani , somewhat longer than in greavesi . Eyeless. Mandible with a large acute apical tooth followed by a series of six denticles, distal one of which slightly enlarged. Visible terminal maxillary and labial palpomeres proportioned as in P. angusticeps . General form of mesosoma as in P. dammermani . Declivitous face of propodeum, viewed from above, moderately concave, depth of concavity about one-third distance between dorsal corners of posterolateral propodeal lamellae. Petiolar node as in figure 21; posterior face moderately concave in side view, its surrounding flange feebly emarginate at dorsal mid-line. Subpetiolar process well developed, similar to that of P. greavesi , but shallower and with ventral edge distinctly concave in side view.

Pilosity reduced, as is normal for the genus; pubescence extremely fine and very sparse, most abundant on second segment of gaster, virtually lacking on head, mesosoma and node. Sculpturation almost exactly as described above for P. dammermani . Colour rich golden-brown, as in the type of P. dammermani .

Holotype [[ worker ]] Solomon Islands: Guadalcanal, Mt. Austen, Honiara, 25. ii. 1963 (P. J. M. Greenslade). The unique holotype is deposited in the Museum of Comparative Zoology, Harvard University.

Distribution. - Known only from type locality.

Biology. - The holotype was collected in a Berlese funnel sample of leafmould from the floor of undisturbed rainforest, at an elevation of about 1000 feet.

Relationships. - This species is clearly close to P. dammermani , and is distinguished from it mainly by the shorter petiolar node (lateral petiole index 93, compared with 115 - 120 in dammermani ), with a much more distinct subpetiolar process. The Australian P. greavesi is also related, but it has an even shorter petiolar node (lateral petiolar index 82 - 83), which is thicker in dorsal view (petiolar node index 66 - 69, opposed to 57 in salomonis ), and somewhat shorter antennal scapes (SI 85 - 87, compared with 97 in salomonis and 103 in dammermani ). P. salomonis bears a general resemblance to the east African P. guineensis , but the two differ in proportions, especially those of the petiolar node, and in the intensity of sculpturation.