Basiceros redux ( Donisthorpe 1939 )
A taxonomic revision of the dirt ants, Basiceros Schulz, 1906 (Hymenoptera, Formicidae)
Probst, Rodolfo Da Silva
Brandão, Carlos Roberto Ferreira
Zootaxa
2022
2022-06-02
5149
1
1
75
Probst & Brandão
2022
Probst & Brandão
2022
[625,865,906,933]
Insecta
Formicidae
Octostruma
Animalia
Hymenoptera
68
69
Arthropoda
species
reducta
comb. nov.
Basiceros redux( Donisthorpe 1939)=
( Fig 29) Type-material: holotype(male), Donisthorpe 1939: 152, GUYANA. Type-locality: Guyana(“ British Guiana”): Kaieteur Savannah, 5.ix.1937(O.W. Richards) (MNH1014339) (examined). Incertae sedisin Rhopalothrix: Brown & Kempf, 1960: 164. Combination in Basiceros: Bolton1995: 80. Status as species: Kempf 1972: 227; Bolton1995: 80.
Comments. Brown & Kempf (1960), while mentioning the taxonomic uncertainty regarding Basiceros-genus group males, added that Rhopalothrix reduxcould 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 holotypeconditions, a detailed examination revealed unique features present of Basiceros reduxwhen compared to other “basicerotine” males: 1. Mandibles—shape and dentition: most Basicerosmales 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: Basicerosmales 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. reduxthe head is rounded and the occipital margin lacks a neck; 3. Antennae: antennomeres of B. reduxare subequal from A3 to the apical segment, a condition not observed in any Basicerosmale examined for this study; 4. Ocelli: in general, Basicerosmales 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. reduxthe posterior face of mesoscutellum is strongly truncated and the metanotal band is extremely reduced, giving the mesoscutum + mesoscutellum set an aspect of plateau. In Basicerosmales, the posterior margin of mesoscutellum is rounded and the metanotum, although reduced, is detached from the mesoscutellum; 6. Petiolar node in dorsal view: for Basicerosmales is elongated, longitudinally rectangular. In B. reduxand the known males of Octostruma, Rhopalothrix, and Eurhopalothrix, the node is transversally rectangular; 7. Postpetiolar node in dorsal view: in Basicerosmales 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 Basicerospossess finely punctuate to reticulate integument and a more abundant pilosity; 9. Propodeal projections: Basicerosmales have short projections, sometimes angled. In B. reduxthe propodeum is armed with a well-developed triangular and lamelliform projection, similar to observed for Octostrumamales; 10. Forewing venation: in B. reduxthe vein M+Cu has a spectral basal portion, similarly to observed for Octostrumamales, whereas in Basicerosmales that vein is invariably complete. Eurhopalothrixmales tend to have M+Cu completely spectral; 11. Forewing venation II: submarginal cell 1: known Rhopalothrixmales have the submarginal cell 1 open (for Eurhopalothrixmales, 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 Eurhopalothrixmales). This set of characteristics are absent in B. redux, with the male having a submarginal cell 1 closed, feature shared by Basicerosand Octostrumamales. Additionally, B. reduxpresents another configuration for other veins above cited; 12. Pterostigma: Eurhopalothrixmales lack the pterostigma or it is poorly developed. Both Basicerosand Octostrumashare a conspicuous pterostigma (for the latter, in some males it can be slightly narrower and not greatly developed); 13. Tegula: in B. reduxthe tegulae are round, contrasting with other Basicerosmales, where they are subrectangular and with the posterior margin convex; Dietz (2004: 151)also proposed transferring B. reduxto Octostrumabased on wing features. In addition, Dietz suggested that B. reduxcould be a male of O. iheringi, based on the pilosities of the petiolar peduncle and ventral face of the postpetiole. However, the current knowledge of Octostrumamales is considerably scarce, therefore preventing a correct association of Basiceros reduxto a valid Octostrumataxon.
4029332380
[151,836,1011,1035]
Guyana
GUYANA
68
69
1
holotype