Myrmecina complexes of Southeast Asia

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Based on Okido, Ogata, and Hosoishi (2020)

Myrmecina gracilis complex

Characterized by the small eyes (< 0.12 mm), the flattened mesosoma, long and posteriorly directed propodeal spine, and first gastral tergum that is concave at the anterior margin in dorsal view and sculptured on the dorsum. Distributed in N. Vietnam, Thailand and Borneo.

The propodeal spine extends to the vertical posteriormost limit of the propodeum, and is at the almost same level of the flattened mesosoma. The apex of the spine is acute and directed posteriorly, though some variations occur with species. The long, acute and horizontal spine is apomorphic, but also observed in some species such as Myrmecina spinosa and Myrmecina tridentata. The concave anterior margin of the gaster forms rounded lateral corner in each side. This state is apomorphic, but again observed in several species in other species groups such as Myrmecina aspera, Myrmecina elegans, M. spinosa and M. tridentata. The species of this complex tend to be small in size.

Myrmecina macrops complex

Characterized by having large eyes, broadened head, and the head smooth and shining or foveolate. Distributed in the Philippines, Sumatra, Malay Peninsula, Borneo, Java.

All these characters seemed to be derived states but each of them can be observed independently in different species complexes of the genus. Myrmecina maryatiae would be close to the complex in having the similar shape of the head, but the shape of the pronotum and the surface sculpture are different from those in the complex.

Myrmecina spinosa complex

Characterized by the backwardly projected occipital corners of the head. Distributed in Thailand, S. Malay Peninsula, Borneo, Sumatra and Java.

This unique shape of the head is an autapomorphy of the complex and somewhat similar to that of Gnamptogenys species of the Ectatomminae. Species of this complex are relatively larger than other species. Among 5 species of the complex, M. spinosa and M. tridentata share the distinct projections on the mesosoma including anterior dorsolateral and anterior ventrolateral denticles on the pronotum, the eumetanotal spines and the propodeal spines, the shape of the masticatory margin of the mandible, and the concave anterior margin of the first gastral tergum.

Myrmecina vieti complex

Well defined as having a sharp ridge of the shield wall on the lateral portion of the clypeus in front of the antennal insertions. Distribution of the species complex is restricted to E. Asia.

The shield wall is unique and represents a derived state among the genus Myrmecina. In the tribe Crematogasterini, Acanthomyrmex has an incomplete ridge originated from the frontal lobe but low and indistinct in front of the antennal insertion. Pristomyrmex and Perissomyrmex have a distinct ridge surrounding the frontal area of the antennal insertion, but the anterior margin of the clypeus hides under this ridge. The shield wall in the M. vieti complex and its ridge have the same property judging from their position and the connection to the frontal lobe. At least the structure in the M. vieti complex would be homologous among the members, because the anterior margin of the clypeus is not hidden. Another character demarcating the M. vieti complex is the shape of the propodeal lobe. The lobe is reduced and low in this complex, while is more or less distinct in others. The same state is also observed in several species including Myrmecina asthena, Myrmecina breviata, Myrmecina dasynota, Myrmecina dechai, etc. This would be a secondary reduction. From these characters discussed above, the M. vieti complex would be a monophyletic group having these synapomorphies.

no complex

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