Rhopalothrix mandibularis

Rhopalothrix mandibularis
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Rhopalothrix
Species:	R. mandibularis
Binomial name
Rhopalothrix mandibularis Guerrero & Grajales-Andica, 2024

This species inhabits humid forests between 1400 and 1700 m above sea level. The holotype and several paratypes were collected in fragments of humid gallery forest and Guadua (bamboo) forest in the city of Armenia. All known specimens are from Winkler samples of sifted leaf litter.

Photo Gallery

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  Guerrero et al. (2024), Figure 7. Rhopalothrix mandibularis holotype worker (CBUMAG:ENT:35947). A, full-face view. B, lateral view. C, mandible distinguishing the teeth of the apical fork; drawing inserted showing the arrangement of the teeth of the apical fork of the mandible. D, dorsal view. Scale bars: 0.5 mm.

Identification

Mandible elongated, much longer (MdL > 0.48) than those of other species in the isthmica clade, mandibles with outer and masticatory margins subparallel to each other and curving inward at tip; labrum with two slender subrectangular lobes, notch deep; propodeal tooth large, acute, right angled to declivitous face of propodeum, infradental lamella poorly developed, forming a thin rim.

This species is placed in the diverse isthmica clade because it shares the two synapomorphies proposed by Longino and Boudinot (2013). Rhopalothrix mandibularis, however, has been widely confused in some Colombian collections with Rhopalothrix ciliata due to its similarity in mandibular shape, the shape of the two lobes of the labrum and the depth of the sinus. Rhopalothrix mandibularis can be differentiated from R. ciliata by the absence of squamiform setae on the rostrum, the latter with specialized setae and a flattened surface on the rostrum. Also, mandibles are longer and thinner along their length in R. mandibularis while in R. ciliata they are short and broad; in R. ciliata the tip of the labral lobes can reach up to half the length of the mandible, but in R. mandibularis the anterior margin of the labrum barely reaches the first tooth of the mandible.

Habitus of the worker of Rhopalothrix mandibularis is similar to that of Rhopalothrix stannardi, but the mandible length is remarkably different between the two, as well as the mandible dentition; R. mandibularis has three teeth located towards the middle of the masticatory margin (the most basal tooth is far from the base), while in R. stannardi the three teeth are equidistant, with the most basal tooth starting at the base of the masticatory margin. Another different feature is the infradental lamella, which is very poorly developed in R. mandibularis, while in R. stannardi the lamella is broad and descends almost perpendicularly from the tooth.

Keys including this Species

• Key to Colombian Rhopalothrix

Distribution

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  Guerrero et al. (2024), Figure 2. Distribution map of Rhopalothrix species in Colombia.

Latitudinal Distribution Pattern

Latitudinal Range: 4.6° to -3.5°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: Guerrero et al., 2024

Distribution based on type material

Colombia (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

Expand Explore Overview of Rhopalothrix biology  Longino and and Boudinot (2013) - Knowledge of the biology of the Rhopalothrix isthmica clade of Rhopalothrix is conjectural; a nest has never been recovered and a live specimen never seen. What we know is based on locations and frequencies of capture using various mass-sampling methods. Specimens are known from wet to moderately seasonal forest, from sea level to 2140 m elevation. At higher elevation, they are found in diverse mesophyll forest and in forests with various combinations of Liquidambar and montane oak. In Costa Rica, they are restricted to the wet forests of the Atlantic slope, to 1500 m on the Barva Transect in the Cordillera Volcánica Central and to 800 m in the Cordillera de Tilarán. The genus is unknown from the Monteverde cloud forest at 1500 m, the lowland wet forests of the Osa Peninsula, and the lowland tropical dry forests of Guanacaste, in spite of intensive collecting efforts in these areas. Further north in Central America they can occur at higher elevations. In quantitative sampling at La Selva Biological Station, in the Atlantic lowlands of Costa Rica, occurrences were relatively more frequent in soil/litter cores than in samples of sifted litter from the soil surface. This suggests that nests are subterranean, with workers only occasionally venturing up into the litter layer. Dealate queens are known for a few species, occurring occasionally in Winkler or Berlese samples. Alate queens of one La Selva species were found in canopy fogging samples, one each in two separate fogging events. Oddly, alate queens have not been found in the many Malaise samples from La Selva. Males are only known for Rhopalothrix apertor. ‎

Castes

Queen and male unknown.

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

• mandibularis. Rhopalothrix mandibularis Guerrero & Grajales-Andica, in Guerrero et al., 2024: 141, figs. 2, 7 (w.) COLOMBIA.

Type Material

• Holotype. Colombia • 1 worker; Quindío, Armenia, Sena; 4.56931°N, 75.64347°W; 1565 m a.s.l.; 18 Feb. 2020; A.F. Grajales-Andica & D.R. García-Cárdenas legs.; ex sifted leaf litter, gallery forest; CBUMAG:ENT:35947.
• Paratypes (N = 4). Colombia • 1 worker; same data as for holotype; CIUQ-025287. • 1 worker; Quindío, Armenia, Parque de la Vida; 4.54614°N, 75.65933°W; 1515 m a.s.l.; 8 Oct. 2020; A.F. Grajales-Andica & D.R. García-Cárdenas legs.; ex sifted leaf litter, gallery forest; CIUQ-025288. • 1 worker; Quindío, Armenia, Yulima; 4.5515°N, 75.671°W; 1485 m a.s.l.; 8 Feb. 2020; A.F. Grajales-Andica & D.R. García-Cárdenas legs.; ex sifted leaf litter, gallery forest; CIUQ-025289. • 1 worker; Valle del Cauca, Vda. El Tenjo, Finca La Alejandría; 3.51667°N, 76.16667°W; 1703 m a.s.l.; Aug. 2006; Grupos Hormigas U. V. legs.; ex sifted leaf litter; MUSENUV HOR 008.

References

• Guerrero, R.J., Grajales-Andica, A.F., Fernández, F., Tocora, M.C., Fiorentino, G., García, D.R. 2024. The ants of the genus Rhopalothrix Mayr, 1870 (Hymenoptera, Formicidae, Myrmicinae) in Colombia. ZooKeys 1191, 129–150 (doi:10.3897/zookeys.1191.110418).