NOTES ON SOME AUSTRALIAN AND MELANESIAN BASICEROTINE ANTS (HYMENOPTERA: FORMICIDAE)

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INTRODUCTION
This paper supplements my recent review of the Indo-Australian ants of the myrmicine tribe Basicerotini (Taylor 1968).It brings up to date the information available on distribution and variation of several previously described species, and a new species, Eurhopalothrix cinnamea, is described from Manus Island in the Bismarck Archipelago.The E. cinnamea types were collected by the Danish "Noona Dan" expedition, and were provided for study by Dr. Bsrge Petersen of Universitets Zoologiske Museum, Copenhagen.Rev. B. B. Lowery collected much of the other material, which he has generously deposited with the Australian National Insect Collection (ANIC).Abbreviations and definitions of measurements and indices follow those of the 1968 paper, which should be consulted for references and other data.Six worker specimens generally resemble the holotype (ANIC), but two have supernumerary large orbicular cephalic hairs.The types, and the four apparently normal current specimens, have 16 hairs arranged in three rows across the frons.The anterior row of eight hairs is divided into two bilateral series of four by a gap at the midline, which slightly exceeds the other interspaces (Taylor 1968, Fig. 1).One of the anomalous Burringbar Range specimens has a fifth hair in the right anterior series, and the other has an extra hair between the right inner members of the anterior and middle series.Neither specimen appears to have accidentally lost any bilateral homologues of these supernumerary hairs.
A queen collected with these workers is too badly worn and encrusted for formal description.She has a complete thoracic exoskeleton and was obviously once winged.Her pilosity is badly obscured or damaged, but other comparable features resemble those of the workers.She has the following dimensions: TL c.  hair pattern.The usual condition, with 10 specialised erect clavate hairs in the anterior row (Brown and Kempf 1960, Fig. 46), is seen in eight specimens; five have 12 hairs symmetrically arranged, and one has 11, including a supernumerary on the left side.All these specimens show no signs of loss of other cephalic hairs.I have seen 19 workers from the Burringbar Range colony; 15 have 10 anterior cephalic hairs, one has 12, and three have 11, with supernumeraries on either the left or right.Two workers from Mt. Coot-tha, Brisbane (members of a series from which Brown and Kempf (1960, p. 220) selected a paratype) have 10 anterior cephalic hairs, while a third has the pilosity damaged, but there are six hairs on the right side; a fourth specimen is too damaged for analysis.A worker from Lake Eacham National Park, near Atherton, N. Queensland, has 10 hairs in the anterior row.
Obviously caution is needed when using chaetotaxonomic characters in basicerotine studies.Couplet 9 of my 1968 key to the Indo-Australian species requires modification in the light of this information.
Ground pilosity of minute bristle-like hairs about 0.01 mm long, extremely reduced and sparse where present; virtually absent on head except outer crests of occipital lobes and around eyes; elsewhere noticeably developed only on dorsa of promesonotum, petiole and postpetiole.Face of scape moderately covered by longer (c.0.03 mm) narrowly clavate hairs; its outer edge with about 10 erect, narrowly clavate hairs, grading distally from c. 0.08-c.0.04 mm long.A few similar hairs on apex of gaster and posterior area of its first sternite.Legs, proximal to femoral apices, with dense small hairs like those on face of scape; tibiae and tarsi with similarly dense but broad flattened hairs about 0.03 mm long and 0.02 mm wide.A pair of narrowly clavate erect specialised hairs c. 0.1 mm long on frons (Figs. 1, 2).Pubescence noticeable only on antennal scapes.General colour of head, body and appendages even, rich, golden chestnut brown; pilosity and pubescence yellowish-white.This species is not especially striking or unusual.It clearly belongs in the group of E. procera (Taylor 1968), and appears to be part of a Melanesian radiation from procera-like stock, which also includes the Solomon Islands species E. greensladei and E. isabellae.
E. cinnamea runs to E. isabellae in couplet 3 of my 1968 key to the Indo-Australian Basicerotini.These species may be differentiated by inserting the following couplet 3a into the key: 3a(3).Propodeal teeth well developed, supporting broad infra-dental lamellae, a triangular area of propodeal dorsum anterior to their bases distinctly concave, and more or less clearly set off from the remaining dorsum.Colour medium-dark reddish brown (Solomon Islands : Ysabel and Vella Lavella) Rhopalothrix orbis Taylor New record-NEW SOUTH WALES: Burringbar Range, c. 15 km S of Murwillumbah, colony in roots and litter on buttress of Trisfania conferta, medium sclerophyll forest, c. 120 m (2.ix.1968;B. B. Lowery) ANIC.