Crematogaster ransonneti, Mayr, 1868

Hosoishi, Shingo, 2020, Taxonomic review of the Crematogaster ransonneti-group in Asia, with description of a new species from Malaysia (Hymenoptera: Formicidae: Myrmicinae), Raffles Bulletin of Zoology 68, pp. 759-768 : 760-761

Crematogaster ransonneti -group

The Crematogaster ransonneti -group can be distinguished from other Asian Crematogaster species by the following characters: (1) mandible with four teeth; (2) three-segmented antennal club; (3) deep metanotal groove; (4) propodeal spine well-developed and long (PSL 0.21–0.63); (5) propodeal spine directed posterolaterally in dorsal view; (6) petiole diamond-shaped and broadest at mid-length; (7) petiole distinctly wider than postpetiole (WI 73–92); and (8) postpetiole weakly globule but without distinct longitudinal median sulcus. This species group is similar to the C. fraxatrix -group in having a diamond-shaped petiole ( Hosoishi & Ogata, 2014), but can be distinguished from the latter by the aforementioned characters (3), (4), and (5). Using a comprehensive molecular phylogeny, Blaimer (2012b) revealed a sister relationship between C. fraxatrix and C. ferrarii (as C. cf. ferrarii ). The phylogenetic position of the C. ransonneti -group is currently unknown because fresh material of the group was unavailable for me. In the future, molecular phylogenetic analysis using fresh material will help verify the relatedness of the C. ransonneti -group with other species, which is currently inferred mostly from morphology.

This species group is distributed throughout parts of South and Southeast Asia ( Fig. 1 ), but has not been recorded from the Indochinese Peninsula.

List of species included in the Crematogaster ransonneti - group.

C. cornuta Crawley, 1924

C. keris , new species

C. ransonneti Mayr, 1868

Key to species based on the worker caste.

1. Dorsal surface of head smooth and shiny. Promesonotum smooth and shiny ..................................................... ransonneti

– Gena sculptured or striated with longitudinal rugulae. Promesonotum striated with rugulae ......................................2

2. Posterior half of head with longitudinal rugulae. Mesopleuron and lateral surface of propodeum with longitudinal rugulae. Propodeal dorsum with longitudinal rugulae .............. cornuta

– Posterior half of head smooth. Mesopleuron and lateral surface of propodeum generally smooth. Propodeal dorsum smooth and shiny................................................................................... keris

Figures

Fig. 1. Distribution map of Crematogaster cornuta, C. keris, and C. ransonneti. Open circle = C. cornuta; open square = C. keris; open triangle = C. ransonneti.