Rhopalomastix

AntWiki - Where Ant Biologists Share Their Knowledge
Jump to navigation Jump to search
Rhopalomastix
Rhopalomastix rothneyi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Crematogastrini
Genus: Rhopalomastix
Forel, 1900
Type species
Rhopalomastix rothneyi
Diversity
11 species
(Species Checklist)

Rhopalomastix rothneyi casent0178531 profile 1.jpg

Rhopalomastix rothneyi

Rhopalomastix rothneyi casent0178531 dorsal 1.jpg

Specimen Label

Evolutionary Relationships

Rostromyrmex






Cardiocondyla



Ocymyrmex






Nesomyrmex



Xenomyrmex





Terataner




Atopomyrmex



Cataulacus










Carebara



Diplomorium






Melissotarsus



Rhopalomastix






Calyptomyrmex



Tetramorium





Cyphoidris



Dicroaspis










Aretidris



Vollenhovia





Dacetinops



Indomyrma








Crematogaster



Meranoplus






Lophomyrmex




Adlerzia



Recurvidris






Stereomyrmex




Trichomyrmex





Eutetramorium




Royidris




Malagidris



Vitsika








Huberia



Podomyrma





Liomyrmex



Metapone













Kartidris



Mayriella





Tetheamyrma




Dacatria



Proatta









Dilobocondyla



Secostruma






Acanthomyrmex



Myrmecina





Perissomyrmex



Pristomyrmex









some Lordomyrma



Propodilobus





Lasiomyrma




[some Lordomyrma




Ancyridris



some Lordomyrma









Paratopula




Poecilomyrma




Romblonella



Rotastruma








Gauromyrmex



Vombisidris





Temnothorax




Harpagoxenus



Formicoxenus



Leptothorax













Based on Ward et al. (2014) and Blaimer et al. (2018).

Rhopalomastix workers chew a network of tunnels under the bark of living trees where they nest. Tunnels are inhabited by large numbers of diaspidid scale insects (Yong et al. 2019). Non-specific associations with different genera of trees and diaspidids were recorded in SIngapore, Thailand and Okinawa (Japan) (C. Peeters unpublished). Rhopalomastix is the second ant genus involved in a mutualism with diaspidids, besides Melissotarsus.

Eguchi, Bui and Yamane (2011) - The worker of Rhopalomastix is easily separated from those of other known Vietnamese myrmicine genera by a combination of the following characters: frontal lobes closely approximated; eye relatively large; mesosoma box-shaped; fore- and hindfemora extremely widened and flattened distally; postpetiole broadly attached to gaster.

Keys including this Genus

 

Distribution

Distribution and Richness based on AntMaps

Biology

Yong et al. (2019) - The presence of diaspidid scale insects inside all nests examined is a strong suggestion that they are a source of food for the ants. However, there are no direct observations of feeding or other interactions because ants stop normal activities and take cover as soon as the tunnels are opened. The five genera of diaspidids associated with four species of Rhopalomastix in Singapore all share the remarkable characteristic that females can reach sexual maturity without secreting a hard wax shield. As in Melissotarsus, Rhopalomastix adult females can secrete silk that is used to secure the tunnels. In contrast, Rhopalomastix workers have a sting and lack the extreme leg specialisation legs,

Workers and one larva of Rhopalomastix murphyi together with naked diaspidid Andaspis numerata in galleries chewed under the bark. Note a few scattered shields of different sizes. From Singapore. Photo by Chui Shao Xiong.
Eggs of Rhopalomastix johorensis amid an aggregation of Rhopalaspis peetersi adult female diaspidids and eggs. One naked diaspidid is in the process of ovipositing. From Singapore. Photo by Gordon Yong.


Diaspidid scale insects inside tunnels chewed in live wood by Rhopalomastix workers. Bark has been removed to expose the tunnels. From Thailand. Photo by Christian Peeters.
Rhopalomastix workers and larvae inside tunnels chewed in live wood, together with diaspidids (right). From Thailand. Photo by Christian Peeters.

Castes

Morphology

Worker Morphology

 • Antennal segment count 10 • Antennal club 2 • Palp formula 1,1; 0,1 • Total dental count 2-4 • Spur formula 0, 0 • Sting present

Male Morphology

 • Antennal segment count 12 • Antennal club gradual • Palp formula 1,1 • Total dental count 0 • Spur formula 0, 0

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • RHOPALOMASTIX [Myrmicinae: Melissotarsini]
    • Rhopalomastix Forel, 1900a: 24. Type-species: Rhopalomastix rothneyi, by monotypy.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Eguchi, Bui and Yamane (2011) - The worker of the single Vietnamese species has the following features. Worker monomorphic; head subrectangular; frontal carina and antennal scrobe absent; frontal lobes touching or separated only by a narrow longitudinal impression; median portion of clypeus weakly convex anteriorly, lacking median clypeal seta but bearing a pair of thick and short submedian setae; mandible small, with 4 teeth; antenna 10-segmented, with 2-segmented club; scape very short, extending a little beyond midlength of head when laid backwards; eye relatively large, located well in front of midlength of side of head; mesosoma box-shaped; promesonotal suture absent dorsally; metanotal groove absent; propodeum unarmed; metapleural gland bulla large; propodeal lobe absent; fore- and hindfemora extremely widened and flattened distally; petiole nodiform, with relatively high node, anteroventrally with well-developed subpetiolar process; postpetiole much shorter than high, broadly attached to anteriormost portion of gaster; gastral shoulder absent.

References