.jpg){kind=logo}
Octostruma reducta
| Octostruma reducta | |
|---|---|
| |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | Myrmicinae |
| Tribe: | Attini |
| Genus: | Octostruma |
| Species: | O. reducta |
| Binomial name | |
| Octostruma reducta (Donisthorpe, 1939)
| |
Identification
Distribution
Distribution based on Regional Taxon Lists
Neotropical Region: Guyana (type locality).
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
Countries Occupied
| Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species. |
|
Estimated Abundance
| Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species. |
|
Biology
Castes
Images from AntWeb
 
| |
| Holotype of Basiceros redux. Male (alate). Specimen code casent0900942. Photographer Will Ericson, uploaded by California Academy of Sciences. | Owned by NHMUK, London, UK. |
Nomenclature
The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.
- reducta. Rhopalothrix redux Donisthorpe, 1939c: 152 (m.) GUYANA.
- Type-material: holotype male.
- Type-locality: Guyana (“British Guiana”): Kaieteur Savannah, 5.ix.1937 (O.W. Richards).
- Type-depository: BMNH.
- Inertae sedis in Rhopalothrix: Brown & Kempf, 1960: 164.
- Combination in Basiceros: Bolton, 1995b: 80.
- Combination in Octostruma: Probst & Brandão, 2022: 69.
- Status as species: Kempf, 1972a: 227; Bolton, 1995b: 80.
- Distribution: Guyana.
Taxonomic Notes
This species, described in 1939 from a single male, has proven difficult to place to genus. Rhopalothrix is one of a constellation of similar genera with generic boundaries that have proven difficult to unambiguously define. One problem is there are few males collectively known for these genera. One example of this is that there has been just one male collected (Rhopalothrix apertor) for all of the other 19 species of Rhopalothrix currently described. The most recent evaluation of the characters of the R. redux holotype is from Probst & Brandão (2022). They found:
Brown & Kempf (1960), while mentioning the taxonomic uncertainty regarding Basiceros-genus group males, added that Rhopalothrix redux could be placed in Eurhopalothrix, Rhopalothrix, Octostruma, or Talaridris. Few are the species from the Basiceros-genus group in which the males are known, making it hard to address intraspecific variation. Despite the holotype conditions, a detailed examination revealed unique features present of Basiceros redux when compared to other “basicerotine” males:
1. Mandibles—shape and dentition: most Basiceros males have mandibles somewhat elongate, with the external margin apically curved and 9-14 teeth on the masticatory margin. In Basiceros redux, the mandibles are triangular, having seven or eight teeth;
2. Head shape: Basiceros males have an anteriorly elongated head (the overall head shape has a piriform to subpiriform aspect) and the occipital margin projected and carinate, forming a neck. In B. redux the head is rounded and the occipital margin lacks a neck;
3. Antennae: antennomeres of B. redux are subequal from A3 to the apical segment, a condition not observed in any Basiceros male examined for this study;
4. Ocelli: in general, Basiceros males have the ocelli arranged on the top of the head, surrounded by a conspicuous cephalic crest. In B. redux, although the ocelli are located on the top of the head, the crest is absent;
5. Mesosoma: in B. redux the posterior face of mesoscutellum is strongly truncated and the metanotal band is extremely reduced, giving the mesoscutum + mesoscutellum set an aspect of plateau. In Basiceros males, the posterior margin of mesoscutellum is rounded and the metanotum, although reduced, is detached from the mesoscutellum;
6. Petiolar node in dorsal view: for Basiceros males is elongated, longitudinally rectangular. In B. redux and the known males of Octostruma, Rhopalothrix, and Eurhopalothrix, the node is transversally rectangular;
7. Postpetiolar node in dorsal view: in Basiceros males is nodiform and subglobular, conditions not observed for B. redux;
8. Gastral integument: in opposition to the shiny integument and the sparse pilosity found in B. redux, males of Basiceros possess finely punctuate to reticulate integument and a more abundant pilosity;
9. Propodeal projections: Basiceros males have short projections, sometimes angled. In B. redux the propodeum is armed with a well-developed triangular and lamelliform projection, similar to observed for Octostruma males;
10. Forewing venation: in B. redux the vein M+Cu has a spectral basal portion, similarly to observed for Octostruma males, whereas in Basiceros males that vein is invariably complete. Eurhopalothrix males tend to have M+Cu completely spectral;
11. Forewing venation II: submarginal cell 1: known Rhopalothrix males have the submarginal cell 1 open (for Eurhopalothrix males, the Rs+M vein is in general spectral or slightly tubular, and a close observation shows that it closes the submarginal cell 1) and the veins Rs, M, Cu, and A nebular or spectral in their basal half (similar condition observed for examined Eurhopalothrix males). This set of characteristics are absent in B. redux, with the male having a submarginal cell 1 closed, feature shared by Basiceros and Octostruma males. Additionally, B. redux presents another configuration for other veins above cited;
12. Pterostigma: Eurhopalothrix males lack the pterostigma or it is poorly developed. Both Basiceros and Octostruma share a conspicuous pterostigma (for the latter, in some males it can be slightly narrower and not greatly developed);
13. Tegula: in B. redux the tegulae are round, contrasting with other Basiceros males, where they are subrectangular and with the posterior margin convex;
Dietz (2004: 151) also proposed transferring B. redux to Octostruma based on wing features. In addition, Dietz suggested that B. redux could be a male of Octostruma iheringi, based on the pilosities of the petiolar peduncle and ventral face of the postpetiole. However, the current knowledge of Octostruma males is considerably scarce, therefore preventing a correct association of Basiceros redux to a valid Octostruma taxon.
References
- Bolton, B. 1995b. A new general catalogue of the ants of the world. Cambridge, Mass.: Harvard University Press, 504 pp. (page 80, combination in Basiceros; new synonymy, catalogue)
- Brown, W. L., Jr.; Kempf, W. W. 1960. A world revision of the ant tribe Basicerotini. Stud. Entomol. (n.s.) 3: 161-250 (page 164, see also)
- Donisthorpe, H. 1939d. Descriptions of several species of ants (Hymenopt.) taken by Dr. O. W. Richards in British Guiana. Proc. R. Entomol. Soc. Lond. Ser. B 8: 152-154 (page 152, male described)
- Probst, R.S., Brandão, C.R.F. 2022. A taxonomic revision of the dirt ants, Basiceros Schulz, 1906 (Hymenoptera, Formicidae). Zootaxa 5149 (1): 1-75 (doi:10.11646/zootaxa.5149.1.1).
References based on Global Ant Biodiversity Informatics
- Brown W. L., Jr., and W. W. Kempf. 1960. A world revision of the ant tribe Basicerotini. Stud. Entomol. (n.s.) 3: 161-250.
- Donisthorpe H. 1939. Descriptions of several species of ants (Hymenopt.) taken by Dr. O. W. Richards in British Guiana. Proceedings of the Royal Entomological Society of London. Series B 8: 152-154.
- Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
- Probst da Silva R. 2015. Revisao taxonomica e analise filogenetica de Basiceros Schulz, 1906 (Formicidae, Myrmicinae, Basicerotini). Master Thesis Museu de Zoologia da Universidade de Sao Paulo. 263 pages.