Meranoplus diversus group

Schodle 2007. Plate 1.

Although several of the species found in this group are among the largest in Meranoplus, the diversus group comprises medium sized to smaller species as well. Species are readily separated from members of other groups by the distinctive clypeal morphology. The posterior (dorsal) part of the clypeus is constructed as a massive plate fit in between the anterolateral frontal corners; it may show various forms of elaborations such as keels or plates or, it may be distinctly excavated at its apparent anterior margin which frequently surpasses the anterolateral frontal corners in length. The true anterior clypeal section is strongly concave in lateral view and hidden below the posterior section. Most species have large, massive heads in relation to their body size. Mandibles are short, stout and armed with three to five teeth and are mostly overhung by the clypeal plate. These are frequently worn down completely so that the masticatory margin may secondarily be edentate. The compound eyes generally are of moderate size (except in occidentalis and taurus). The frontal carinae are markedly narrower than the head, so that the genae, eyes and antennal scrobes are partly visible in dorsal view. The promesonotal shield either has very reduced blunt (to almost absent) projections or prominent spines, frequently laterally flanged and translucently margined. The petiole is triangular to box-shaped, the postpetiole nodular with an antero-ventral tooth of variable size. Species are unicolorous or bicolored with the gaster and appendages usually brighter than the remainder of body. Both color forms may occur in one and the same species.

In general only the larger species with a large, bulbous head capsule and reduced projections on the promesonotal shield are assigned to the M. diversus group. However the majority of the species are considerably smaller (see also Andersen, 2000). Due to various characteristics such as shape of the dorsal shield, clypeal structure and sculpturation of the dorsal surface species cluster to subgroups. These are not recognized in detail herein, since these subgroups are not clearly defined.

Species either have a limited distribution, a circumstance that may be due to climatic and ecological factors, while others are widely distributed without significant restriction to their radiation (none of the species herein treated is known to have crossed the Torres Strait). Some species show a higher degree of morphological plasticity than do others. For this reason, some material has only been tentatively assigned to species. Further material will be needed to clarify the taxonomic position of these ‘left overs’.

Members of the M. diversus group nest in the ground, as evidenced by the large number of pitfall specimens, label data and observations of collectors. They are granivores and thus play an important role in seed dispersal (Taylor & Brown, 1987; Andersen, 2000, and citations therein), comparable to that of Messor, a genus missing in Australia.

Key to Meranoplus diversus group workers

Based on: Schödl, S. 2007. Revision of Australian Meranoplus: the Meranoplus diversus group. Memoirs of the American Entomological Institute 80:370-424.