Polyrhachis mucronata species-group

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The species in this group are members of the subgenus Myrmhopla.

Species

Identification

Key to Sulawesi Polyrhachis mucronata-group species

Overview

The Polyrhachis mucronata species-group of the subgenus Myrmhopla was delimited by Dorow (1995) who subdivided the earlier established P. dives-group (Emery, 1925). Dorow listed 36 species and subspecies within the group, however, the status of several subspecific forms still remains unresolved. Two new species were recently described from Sulawesi (Kohout, 2008) and one species is considered a junior synonym (see below). Only a single species of the group, Polyrhachis mucronata, is relevant to the Australian fauna.

Diagnosis

Worker

(modified from Dorow, 1995) Small to medium-sized ants (HL 1.25-2.10) with general characteristics of the genus. Mandibles mostly longitudinally striate or finely rugose with numerous piliferous pits. Anterior clypeal margin with shallow, median flange (as in P. mucronata), or shallowly truncate (as in Polyrhachis retrorsa). Head usually semicircular in side view, oval in frontal view; genae immarginate. Eyes moderately to strongly convex, clearly exceeding lateral cephalic outline in full face view. Mesosoma totally immarginate, usually highly convex and relatively short (as in P. mucronata), but also somewhat elongated and distinctly less convex (as in Polyrhachis tristis). Pronotum armed with acute teeth (as in P. mucronata), or rarely with long slender spines (as in Polyrhachis amana), or simply rounded (as in Polyrhachis moeschi). Propodeal spines relatively long and strong in most species, however, also short (as in Polyrhachis orpheus). Petiole columnar with a pair of lateral spines usually embracing first gastral segment; spines mostly slender, but also remarkably massive (as in [[Polyrhachis lucidula)] and Polyrhachis ridleyi). Dorsum of petiole with a pair of more-or-less distinct intercalary teeth, except in some species (e.g. P. amana and P. orpheus). Sculpturation of head, mesosoma and petiole ranging from rather smooth and highly polished (as in P. emmae) to closely punctate (as in Polyrhachis oedacantha). Gaster usually more finely sculptured, shagreened and polished, only rarely closely punctate, opaque (as in Polyrhachis tristis). Body pilosity and pubescence virtually lacking in most species, however, in Polyrhachis mitrata and P. retrorsa whole body covered with rather diluted, whitish pubescence. Body mostly black, rarely with purple metallic reflections (as in P. oedacantha and Polyrhachis phalerata). Gaster black or reddish-brown with appendages ranging from orange or light reddish-brown to black.

Polyrhachis mucronata nest

Queen

Queen very similar to worker with usual differences indicating caste, including three ocelli, complete thoracic structure and wings. Body armature, notably propodeal and petiolar spines distinctly shorter and stronger. Sculpturation, pilosity and colour essentially as in worker.

Distribution and biology

The Polyrhachis mucronata species-group is distributed throughout east and south-east Asia (China, Philippines, Laos, Malaysia, Thailand, Myanmar, India, Sri Lanka), extending south to Indonesia (Sumatra, Java, Sulawesi) and New Guinea (including Bismarck Archipelago), reaching the southern limit of its distribution in northern Queensland. The known members of this group are arboreal nesters, building nests of silk and vegetation debris upon the leaves of rainforest trees and shrubs, mostly in the lower arboreal zone (see image).

Related Pages

References