Kempfidris inusualis

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Kempfidris inusualis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Solenopsidini
Genus: Kempfidris
Species: K. inusualis
Binomial name
Kempfidris inusualis
(Fernández, 2007)

Monomorium inusuale casent0217050 p 1 high.jpg

Monomorium inusuale casent0217050 d 1 high.jpg

Specimen Labels

Fernández et al. (2014) - Almost nothing is known about the natural history of K. inusualis comb. nov. Most of the specimens studied were apparently obtained from leaf-litter samples. The nest series collected by J. Lattke in the Venezuelan Amazon was obtained from a rotten stick, also harboring a termite nest, on the ground next to an airstrip. The habitat there is open scrub to low trees on white sandy soil that is seasonally flooded by dark, colored waters. Interestingly, all the known samples were collected between July and September, suggesting a more intense activity in this period, which coincides with the low level of the rivers in the Amazon Basin. All things considered, this could also be a collecting artifact, as the aforementioned period approximately coincides with academic holidays in many universities and represents a lower probability of conflict between lectures and field trips.


The sole member of the genus Kempfidris.

Fernández et al. (2014) - The strongly reduced eyes and the long diastema between the three apical teeth and the basal tooth do not appear to be common in myrmicines. Kempfidris is reminiscent of Cryptomyrmex regarding the mandibular configuration (four teeth with a diastema), clypeal structure (elevated median area), single median seta along the anterior clypeal margin, and reduced number (2) of maxillary palp segments. However, Cryptomyrmex has a different antennal structure (12 segments, the last two forming a club), modified hairs along the mandibular masticatory margin and subcutaneous ommatidia. Reduced eyes can be found in the African fossulatum-group of Monomorium (Bolton 1987), as well as in Carebarella.

The most outstanding feature of Kempfidris is the series of minute, hair-bearing tubercles or cylindrical pegs on the abdominal apex. Most are concentrated on the anteromedian portion of the pygidium and some on the posteromedian portion of abdominal tergite VI, a position that would coincide with the position of the pygidial gland, which opens between abdominal tergites VI and VII (Billen 2009). The structure of the micropegs with their associated hairs also hints at some sort of glandular function, or possibly a mechano-reception function during stinging, but a more convincing explanation will only be possible after a histological study. Whatever the function of these tubercles, they appear to be an autapomorphic structure, absent in other Myrmicinae and probably in other ants as well.

Despite its broad distribution, specimens of K. inusualis are relatively uniform in size and general aspect. As already mentioned by Fernández (2007), the main differences regarding geographic variation involve slightly distinct propodeal shapes, such as a shorter dorsal face in the Ecuadorian specimens. Specimens from Rondônia, Brazil, differ from other conspecific workers by their darker color (almost black) and more prominent propodeal crests that form small denticles. Given the similarity among the samples examined, we decided to consider these morphological differences as intraspecific variation.


Fernández et al. (2014) - Despite the fact that this species is broadly distributed in South America, records of its occurrence are extremely scarce. Until recently, Kempfidris inusualis was known only from the type series examined by Fernández (2007) and a nest series collected by John Lattke in 2006. A 2010 field expedition (which included R.M. Feitosa) to the southern limits of the Brazilian Amazon Forest (state of Rondônia, near the border with Bolivia) yielded a series of K. inusualis workers extracted from a Winkler sample.

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality), Colombia, Ecuador, Peru, Venezuela.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb



Known only from the worker caste.


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

  • inusualis. Monomorium inusuale Fernández, 2007b: 135, figs. 1, 2 (w.) BRAZIL. Combination in Kempfidris: Fernández, Feitosa & Lattke, 2014: 7.

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



Fernández et al. 2014. Fig. 1. Kempfidris inusualis (Fernández, 2007) comb. nov., worker from Benjamin Constant, Amazon, Brazil (ICN). SEM photographs. A. Head in full face view. B. Head in dorsal oblique view. C. Mesosoma in lateral view. D. Apex of metasoma showing the cylindrical micro-pegs.

(mm), holotype (paratypes, n=3): HW 0.48 (0.46-0.48); HL 0.57 (0.57-0.62); SL 0.37 (0.37-0-41); EL 0.03 (0.03); WL 0.72 (0.70-0.72); PL 0.25 (0.25); PPL 0.18 (0.18); GL 0.73 (0.73-0.80); TL 2.58 (2.58-2.61). Indices: CI 84 (74-84); SI 77 (77-89).

Fernández et al. (2014) - Head longer than wide. Sides of head subparallel, slightly wider anteriorly, broadly rounded into posterior border, which is more or less straight. Antennal insertions relatively close together, separated by no more than three times the apical scape width. Scape fails to reach vertexal border. In lateral view, promesonotum slightly convex, mesonotal margin weakly convex to almost straight. Metanotal groove very deep, well-marked. Propodeal spiracle circular, opened posteriorly. Petiole with peduncle and node well differentiated, the node with subparallel anterior and posterior faces, dorsum convex. Petiolar spiracle at base of node. Petiolar ventral process shaped as rounded, anteroventrally directed tooth. Postpetiole subcampaniform, with a conspicuous transverse, ventral carina. Mandibles, most of promesonotum, dorsum of petiole and postpetiole, and gaster smooth and shining. Head with longitudinal, irregular rugulae mixed with dense foveae. Posterior portion of promesonotum with feeble, short rugulae. Most of mesopleura with irregular, short, longitudinal striae, mixed with fine reticulation. Most of propodeum and sides of petiole and postpetiole densely reticulated. Declivity of propodeum with several fine transverse carinae, the most posterior more marked. Moderately erect pilosity on head, promesonotum, petiole, postpetiole and gaster, little on propodeum. Scapes with several erect hairs. Longer hairs about 0.15 mm, those of head shorter. Body light brown to black, appendages lighter.

Type Material

Fernández et al. (2014) - Holotype. Worker, Brazil, Bahia, Barrolândia, 16–23 Jul. 1994, S. Lacau (CEPLAC = Laboratorio de Formigas, Centro de Pesquisas de Cacau, Ilheus, Bahia, Brazil). Paratypes. 1 worker, same data as holotype (Insect Collection, Instituto de Ciencias Naturales); 3 workers, Brazil, Amazonas, Benjamin Constant, 21 Nov. 1962, W.L. Brown Jr. (Museu de Zoologia da Universidade de Sao Paulo); 2 workers, Ecuador, Napo, Limoncocha, 1973, M. Rettenmeyer (MZSP, The Natural History Museum).


The name refers to the unusual traits of the ant, and the taxonomical difficulties for their generic placement.