Rhopalothrix amati

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Rhopalothrix amati
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Rhopalothrix
Species: R. amati
Binomial name
Rhopalothrix amati
(Fiorentino, Tocora & Fernández, 2022)

Rhopalothrix amati F2b.jpg

Rhopalothrix amati F2c.jpg

This is an uncommon species, known only from 7 workers distributed in 5 nearby localities. Collections have been in dry forest and second-growth wet forest habitats, all from Berlese or Winkler samples of forest floor litter and rotten wood, in moderate to high elevations (above 1800 m) in the West Andes of Colombia.

Identification

Fiorentino, Tocora and Fernández (2022) - Rhopalothrix amati is likely most similar to Eurhopalothrix bruchi, as they share a somewhat similar coloration pattern, general mesosoma shape, petiole shape, and propodeal lamellas. These two species can be easily distinguished by:

  • the general setation on the face mesosoma and metasoma (abundant specialized setae in R. amati vs. only abundant spatulate ground pilosity in E. bruchi, lacking any specialized setae) (Fig. 4A-C)
  • the head shape (posterolateral margin meeting the anterolateral margin at a sharp angle, giving head a more triangular appearance in R. amati vs. posterolateral margin and anterolateral margin continuously curved, giving head a bilobed and rounded appearance in E. bruchi) (Fig. 4A, B)
  • the mesonotum profile (irregular, with marked prometanotal and mesonotal grooves in R. amati vs. straight in E. bruchi) (Fig. 4C, D).
Figure 4. General differences between Eurhopalothrix bruchi and Rhopalothrix amati. The main differences can be seen on the head capsule (A-B) and the mesonotum profile (C-D): (A) E. amati n. sp. head capsule (IAvH-E-55017), (B) E. bruchi head capsule (head capsule Argentina, CASENT 0173970), (C) E. amati n. sp. Mesosoma, (D) E. bruchi mesosoma. Lines highlight the head capsule shape (A, B), presence of specialized setae (A-C), and mesosoma profile (C, D).

Keys including this Species

Distribution

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

Latitudinal Distribution Pattern

Latitudinal Range: 5° to 5°.

 
North
Temperate 		North
Subtropical 		Tropical South
Subtropical 		South
Temperate
  • Source: Fiorentino et al., 2022

Distribution based on type material

Colombia (type locality).

Distribution based on AntMaps

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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.
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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.
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Biology

Castes

Nomenclature

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

  • amati. Eurhopalothrix amati Fiorentino et al., 2022: 3, figs. 2, 3, 4A,C (w.) COLOMBIA.
    • Combination in Rhopalothrix: Guerrero et al., 2024: 134.

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

Description

Taxonomic Notes

Guerrero et al. (2024) - Holotype and paratype workers (IAvH-55017 and IAvH-55018) and three non-type specimens were analyzed and measured (HW 0.39–0.43) showing a mandibular dentition different from either of the two states described for Eurhopalothrix (Longino 2013). Fiorentino et al. (2022) indicate that the workers of this species have “masticatory margin with a single row of ~13 long needle shaped teeth…”, but this dentition does not match the simple row of 11 similar, low, triangular teeth mentioned for Eurhopalothrix by Longino (2013). Reanalyzing the mandible dentition of the workers, they present a row of between seven (IAvH55005 in AntWeb 2023) to ten teeth (holotype). The shape of the mandible of the workers of this species also does not match those of Eurhopalothrix, being more like the mandible of some undescribed Rhopalothrix (e.g., CASENT0639185 Rhopalothrix jtl014 or CASENT0646264 Rhopalothrix jtl023). It is possible that the triangular shape of the mandible of Rhopalothrix amati has generated the misclassification of this species in the genus Eurhopalothrix. All the workers studied, however, have the subapical tooth larger than the apical one (Fig. 3C), the latter being below the subapical tooth, a combination of traits present in Rhopalothrix. Based on all morphological evidence, we transfer this species to the genus Rhopalothrix generating the following new combination Rhopalothrix amati (Fiorentino, Tocora & Fernández, 2022).

  • Guerrero et al. (2024), Figure 3. Rhopalothrix amati paratype worker (IAvH-55018). A, full-face view. B, lateral view. C, dorsal view. D, portion of the head viewed obliquely showing the mandibles and the apical fork of the left mandible; the black arrow points to the subapical tooth while the white one points to the apical tooth of the apical fork of the mandible. Scale bars: 0.2 mm.

Worker

Holotype: HW 0.44, HL 0.39, SL 0.22, SLL 0.09, ML 0.49, CI 113, SLI 41. (n = 6): HW 0.42-0.44, HL 0.37-0.39, SL 0.22-0.23, SLL 0.07-0.09, ML 0.41-0.49, CI 108-113, SLI 41-54.

Head - In face view, labrum broad and anteriorly bilobed, each lobe ending in 5-7 distinct non-capitate whitish setae; mandible sub-triangular, dorsal surface strongly convex, apical half strongly down-curved, surface punctate; masticatory margin with a single row of ~13 long needle shaped teeth, ninth tooth conspicuously long; scape with very strongly developed basal lobe, anterior half of lobe with sublucid lamella; scrobe deep, sharply delimited dorsally and less so ventrally, sitting below the deep antennal socket; surface of scrobe foveolate; eye minute, comprising 3-4 fused ommatidia; clypeus straight medially with coarse sculpture; sides of head above eyes angulate, surface of face evenly divided into anterior and posterior portions by strongly arcing transverse ridge, ridge terminates at antennal socket below compound eyes; anterior portion rugulose, lacking longitudinal carina; posterior portion flat, feebly rugulose, vertex margin strongly concave; occipital carina distinct; occiput delimited dorsally and ventrally by encircling carina, occiput foveolate; undersurface of head rugulose; postgenal suture a well-developed longitudinal trough.

Mesosoma - Promesonotal profile low, shallowly convex, promesonotal groove deeply impressed dorsally, with distinct carina, posterior margin of promesonotum a short step dropping to sloping face?, dorsal face of propodeum slightly convex; metanotal groove slightly impressed dorsally; dorsal and posterior faces of propodeum distinct, meeting at obtuse angle, dorsal face shorter than posterior face; the posterior face of the propodeum has a longitudinal subrectangular lamella instead of an acute propodeal spine; propodeal spiracle small, directed somewhat posteriorly; entire mesosoma minutely foveolate.

Metasoma - Petiolar peduncle joins anterior face of petiolar node at rounded obtuse angle; anterior face of node meets dorsal face at rounded right angle; posterior face of node short; ventral margin of petiole with large, blunt anteroventral tooth; postpetiole low and broad, with a feeble longitudinal sulcus dorsally; first gastral sternite with anterior sagital keel; petiole, postpetiole, and gaster densely foveolate.

Pilosity - Dorsal surface of scape distinctly lacking ground pilosity, only present on basal lobe; 3-4 projecting spatulate setae on leading edge of scape; dense ground pilosity on clypeus; ground pilosity of face conspicuous, ground setae decumbent, pompon-like, similar in form to the larger specialized projecting setae, but much smaller, about 1/6 the size, denser medially below anterior row of specialized setae, sparser between anterior and posterior rows; projecting specialized setae large, strongly pompon-like, full complement 12, with curved anterior row of 6 and posterior row of 6 on vertex margin; ground setae similar to those on face sparse on promesonotal dorsum, dorsal half of propodeal spines, moderately abundant on first gastral tergite; 1 pair of projecting spatulate setae on mesonotum; legs with dense, spatulate, subdecumbent setae on entire midtibia, and anterior face of hindtibia, somewhat sparser on other surfaces; apices of tibiae ringed with larger spatulate setae; basitarsus and remaining tarsomeres with abundant, strongly spatulate setae; 1 pair of large projecting spatulate setae on lateral margins of dorsal face of petiolar node; 1 pair of projecting spatulate setae on lateral margins of postpetiole; first gastral tergite with 5-6 rows of projecting spatulate setae.

Type Material

  • Holotype worker. Colombia. Risaralda, Pereira. SFF El Otún Quimbaya, Vda. La Suiza Plantación Urapán 7, transecto 2, 04°43’55.91”N, 75°34’43.93”W, 1870 m, Winkler, coll. Reina, M.F and Franco, L.E. [IAvH--E-55017].
  • Paratype. 1 Worker. Colombia. Risaralda, Pereira, Vda. La Suiza, Fca. El Amparo de Niños, Bosque maduro 1, 04°44′47.86″N, 75°36′48.98″W, 1810 m, Winkler, coll. Franco, E.L. [IAvH-E -55018].

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

Etymology

We named this new species in honor of our mentor, friend and colleague Germán Amat, associate professor at the Institute of Natural Sciences of the National University of Colombia in Bogotá. Germán was a great researcher of the insect fauna of Colombia, with a special interest in scarabaeid beetles. He was also a great explorer and field collector, with many contributions to the knowledge of the fauna of Passalidae and other coleopterans. At the University he was always a great teacher, attentive to helping and training many generations of students.

References

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