Probolomyrmex dammermani Wheeler

Probolomyrmex dammermani Wheeler (figs. 17 - 19)

Probolomyrmex dammermani Wheeler, 1928, Psyche, Camb., Mass. 35: 7 - 9, fig. 1, [[worker]] Type locality: Buitenzorg, Java.

Additional description

The following notes are based on a single syntype worker (labelled " cotype ") in the Museum of Comparative Zoology (type No. 26427). The general accuracy of Wheeler's original description has been confirmed by study of this specimen, but a few additions and corrections are indicated.

(1) hl, 0.60 mm.; hw, 0.41 mm.; sl, 0.42 mm.; ci, 68; si, 103; wl, 0.81 mm.; pw, 0.33 mm.; dorsal petiole width, 0.19 mm.; petiolar node index, 58; petiolar height, 0.25 mm.; petiolar node length, 0.30 mm.; lateral petiolar index, 120.

(2) First funicular segment of antenna about one-fifth longer than broad, and terminal segment one-quarter longer than the three preceding segments together.

(3) The two sculptural components normal for the genus present. Fine shagreening everywhere well developed, and overlying puncturation very distinct. Punctures of frons and dorsa of mesosoma, petiole and gaster about 0.01 mm. in diameter and spaced at about the same distance. Postgenal punctures, and those of sides of mesosoma and ventral and lateral aspects of petiole and gaster, larger, averaging about 0.02 mm. in diameter, and variously spaced, from intervals about equal to their maximum diameter to near contiguity.

(4) Mandibular dentition not visible, but apical two maxillary and terminal labial palpomeres with proportions similar to those of P. angusticeps.

Two additional worker specimens in the Museum of Comparative Zoology are apparently referable to P. dammermani and allow extension of its range to the Philippine Island of Negros. One of these is teneral, and was not measured; the other has the following dimensions: HL, 0.60 mm.; HW, 0.40 mm.; CI, 67; WL, 0.88 mm.; PW, 0.31 mm.; dorsal petiole width, 0.17 mm.; petiolar node index, 55; petiole height, 0.26 mm.; petiolar node length, 0.30 mm.; lateral petiolar index, 115. This specimen has lost its antennae, but the other has a scape index of about 100. The mandibular dentition consists of a single large apical tooth followed by a smaller preapical one and five small denticles. The palpal formula is maxillary 4: labial 2 (teneral dissected), with the segmental proportions as in P. angusticeps.

These specimens are very similar to the Javanese syntype in size, general form, sculpturation, pilosity and pubescence. The following slight differences from the syntype are noted: (1) the occipital border is somewhat less concave; (2) the posterior part of the subpetiolar process is more expanded (cf. figs. 18 and 19); (3) the colour, even that of the less teneral specimen, is a much lighter yellowish-brown; this is almost certainly due, however, to that specimen being partly callow.

Figs. 17 - 27. - Indo-Australian species of Probolomyrmex. (17 - 18) P. dammermani Wheeler, cotype worker: (17) head; (18) body, side view. (19) P. dammermani, specimen from Negros, Philippines, petiolar node, side view. (20, 21) P. salomonis sp. n., holotype worker: (20) head; (21) body, side view. (22, 23) P. greavesi sp. n., holotype worker: (22) head; (23) body, side view. (24,25) P. greavesi, paratype queen: (24) head; (25) body, side view. (26,27) P. greavesi, paratype male: (26) head; (27) body, side view. Scale line equals 1.0 mm.

Distribution. - P. dammermani is known from only the two collections discussed above. Indonesia: Java, Buitenzorg (type locality), 12. xii. 1922 (Dammerman); Philippine Islands: Negros, Dumaguete, 16. iv. 1931 (J. W. Chapman).

Relationships. - P. dammermani is closely related to the other Indo-Australian species, P. salomonis and P. greavesi. It is distinguished from them by the proportions of the node and the shape of its subpetiolar process. P. salomonis has a proportionately narrow head, and the antennal scapes of greavesi are somewhat shorter.