Cephalotes minutus

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Cephalotes minutus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. minutus
Binomial name
Cephalotes minutus
(Fabricius, 1804)

Cephalotes minutus casent0173691 profile 1.jpg

Cephalotes minutus casent0173691 dorsal 1.jpg

Specimen labels

Synonyms

A commonly encountered Cephalotes species that is widely distributed and occurs in many habitat types.

Identification

A member of the laminatus clade characterised in the worker by the eyes having a maximum diameter greater than 1/3 of the head length, and, in the worker and in the soldier, by the propodeal spines not expanded ventrally into a lamella. minutus is the sister species of Cephalotes simillimus with which it is very similar and partially sympatric. It is also one of the commonest species of the genus and the one with the broadest geographical distribution in absolute. The heads of soldiers and gynes from the northern range of the species are more flat than those from other areas. An important location of variation which appears to be not geographically correlated is the declivous face of the propodeum: it can be either longitudinally or transversely striate according to the specimens. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Mexico, St. Thomas Island, Belize, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, Panama, Colombia, Venezuela, Trinidad, Guyanas, Brazil, Peru, Bolivia, Argentina, Paraguay.

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina, Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Guyana, Honduras, Lesser Antilles, Mexico, Nicaragua, Panama, Paraguay, Peru, Trinidad and Tobago, Venezuela.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Schmid et al. (2014) found this ant nesting in infructescences (the stem and remains of buds and fruits above the level of the water reservoir in the rosette) of the bromeliad Vriesea friburgensis on Santa Catarina Island, Brazil.

Gillette et al. (2015) in a Chaipas, Mexico field study of twig-nesting ants in coffee plants found C. minutus nesting on plants between 450-950 m in elevation.

Koch et al. (2018) sampled this species in Caryocar barsiliense trees, in southeastern Brazil cerrado, as part of a study examining species interactions in ant-plants.

The biology of many Cephalotes species is not known. Ants in this genus are common in the New World tropics and subtropics and are especially abundant and diverse in the canopies of Neotropical forests. The majority of species are arboreal. Species that live in other strata inhabit smaller trees, bushes or grass stems. These noon-arboreal species, due to their accessibility, are among the better studied members of the genus. There are also species that can be found in downed wood but it is likely the wood housed the colony before it fell to the ground. Soil nests are not known for any species nor do most species appear to extensively excavate plant tissue. They nest instead in preformed cavities. Overall, ants in the genus utilize a wide range of plants. Some species are predictable in their plant use but none appear to have evolved specialized mutualisms with particular plant species.

Worker castes typically include two forms, a worker and soldier, but there are a few species that are monomorphic. The larger soldier caste typically has an enlarged head disk. In some species the head of the soldier is very different from the worker while in others these differences are less pronounced. Queens and soldiers tend to share similar head morphology. Soldiers use their heads to plug the nest entrance. This can be very effective in excluding potential intruders. Other morphological differences between the worker castes are present but these differences have not been studied as well as head moprhology.

The behavioral repertoire of Cephalotes varians has been examined in great detail (ethograms from Wilson 1976, Cole 1980 and Cole 1983). Soldiers do little else besides defend the nest. This specialized soldier behavior is presumed to be the norm for most species. An especially interesting behavior occurs when workers are dislodged from trees: they "fly" towards the tree, often grabbing the trunk well above the ground (video).

Mature nest size varies, by species, from less than a hundred to many thousands of workers. Available evidence suggests most species are monogynous. Queens may mate with multiple males.

The proventriculus of the Cephalotes is peculiar relative to other ants. The morphology of the structure suggests it serves as a powerful pump and filter. This does not appear to lead these ants to have a highly specialized diet as most species appear to be general scavengers. Foragers have been observed feeding on carrion, bird feces, extrafloral nectaries and even tending membracids. Pollen feeding has been observed in some species, and this is somewhat specialized for ants, but it is not evident that any species restricts its diet to this resource in any significant way. Evidence for pollen feeding in Cephalotes has accumulated, in part, via finding digested pollen grains seen in infrabucal pellets. It has been suggested that the morphology of the proventriculus is a specialization for processing pollen.

More research examining all aspects of the biology of Cephalotes is needed. Our present understanding of these ants is largely based on species that live in locations other than the forest canopy, which is where Cephalotes are most common and diverse.

Castes

Worker

Queen

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • minutus. Cryptocerus minutus Fabricius, 1804: 420 (w.) CENTRAL AMERICA. Smith, F. 1862d: 409 (s.); Emery, 1890b: 74 (q.); Wheeler, G.C. & Wheeler, J. 1954b: 155 (l.). Combination in Cryptocerus (Paracryptocerus): Emery, 1915i: 192; in Paracryptocerus: Kempf, 1951: 169; in Zacryptocerus: Kugler, C. 1978a: 474; in Cephalotes: De Andrade & Baroni Urbani, 1999: 194. Senior synonym of quadrimaculatus, volxemi: Emery, 1890a: 68; Emery, 1890b: 74; of exiguus: Kempf, 1958a: 110; of cognatus: De Andrade & Baroni Urbani, 1999: 195.
  • quadrimaculatus. Cryptocerus quadrimaculatus Klug, 1824: 215 (q.) BRAZIL. Smith, F. 1853: 219 (q.); Smith, F. 1860c: 74 (w.). Junior synonym of minutus: Emery, 1890a: 68; Emery, 1890b: 74.
  • cognatus. Cryptocerus cognatus Smith, F. 1862d: 411, pl. 13, fig. 4 (q.) BRAZIL. Combination in Cryptocerus (Paracryptocerus): Emery, 1924d: 307; in Paracryptocerus (Harnedia): Kempf, 1958a: 137; in Zacryptocerus: Brandão, 1991: 385. Subspecies of minutus: Emery, 1924d: 307. Revived status as species: Kempf, 1958a: 136. Junior synonym of minutus: De Andrade & Baroni Urbani, 1999: 195.
  • exiguus. Cryptocerus exiguus Smith, F. 1867: 524, pl. 26, fig. 4 (w.) MEXICO. Combination in Cryptocerus (Paracryptocerus): Emery, 1924d: 307; in Paracryptocerus: Kempf, 1951: 232. Junior synonym of minutus: Kempf, 1958a: 110.
  • volxemi. Cryptocerus volxemi Emery, 1878a: ix (w.) BRAZIL. Junior synonym of minutus: Emery, 1890a: 68; Emery, 1890b: 74.

Description

Worker

Kempf (1951) - Length 3.4 mm. Median head length 0.88 mm; Weber's length of thorax 0.95 mm. Black; the following light reddish-brown: antennae, tips of mandibles, tips of femora, tibiae, tarsi, apical half of basitarsus, apices of first prothoracic tooth, epinotal and peduncular spines, anterolateral border of gaster, distal border of gastral tergites and sternites. Frontal carinae and upper face of tibiae pale yellowish.

Head opaque; slightly longer than broad, broadest behind the eyes; interocular distance somewhat shorter than the maximum length of the head (43:40). Lateral margins of head scarcely sinuate above the eyes. Posterior margin straight mesially, the occipital angles with slightly projecting, subtransversely truncate, partly infuscated, lamellae, the apical border of which is more or less straight. Cheeks strongly marginate beneath, densely covered with flat, appressed silvery hairs. Eyes large, their longest diameter more than 1/3 of median head length. Upper and lower surface of head finely reticulate-punctate, sparsely covered with silvery, slender, simple, flat, scale-like, appressed hairs; slightly larger, denser, and somewhat canaliculate, lying in grooves, in front of the occipital border.

Thorax opaque. Anterior border moderately arcuate; shoulders sharply angulate. Pronotum somewhat expanded laterally behind the shoulders, with two short teeth on each side, the posterior tooth slightly shorter than the anterior. Posterior corners of pronotum projecting, forming a rectangular tooth. Promesonotal suture vestigial laterad, obsolete mesad. Mesonotum on each side with a small, acute, projecting tooth. Mesoepinotal suture not deeply impressed, more or less vestigial. Basal face of epinotum with an anterolateral, smaller recurved spine and a posterior long, slender spine, twice as long as the first, greatly divergent, more than 45° from the longitudinal axis. Declivity not excavated, its sides not conspicuously crested, but finely longitudinally striated, without scales. The entire thorax finely reticulate-punctate, the upper face very little convex longitudinally and transversely, with rather dense, more or less longitudinal, elongate grooves, each containing a flat, canaliculate, appressed silvery scale. Laterotergite of pronotum and mesopleura longitudinally striated, sparsely scaled.

Petiole opaque, transverse, with a long, subacute spine on each side. Postpetiole slightly longer than petiole, transverse, with a somewhat shorter, broader, spine, on each side, more or less rounded apically curving obliquely forward. Sculpture as on thorax, the sparse scales not lying in foveolae.

Gaster subopaque, somewhat elongate, depressed. First gastral tergite with rather narrow, not distinctly set off anterolateral lamellate border, emarginate mesad. Tergites and sternites finely reticulate-punctate. Scale-like silvery hair appressed, sparse and simple, not lying in deep foveolae. erect pile confined to apical half of first sternite and the exposed portion of the tergites 2-4 and the sternites.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 3.12-3.82; HL 0.78-0.98; HW 0.94-1.16; EL 0.31-0.36; PW 0.75-0.96; PeW 0.47-0.58; PpW 0.42-0.48; HBaL 0.28-0.47; HBaW 0.06-0.07; CI 118.4-121.7; PI 120.8-124.4; PPeI 156.2-183.0; PPpI 178.6-195.6; HBaI 21.1-21.4.

Soldier

Kempf (1951) - Length 7 mm. Median head length 1.90 mm; Weber's length of thorax 2.02 mm. Black; the following ferruginous: antennae, tip of femora, tibiae, tarsi. First gastral tergite with a large yellowish-brown spot on each corner.

Head subfulgid; slightly longer than wide (83:82). Frontal carinae arcuate, diverging caudad to above the posterior end of the antennal scrobe, where they form a distinct, very obtuse angle, and are prolonged in the form of a conspicuous, not raised margination above the eyes, fading out before reaching the posterior border of the eyes. Upper surface of head scarcely convex. Occiput sharply truncate, distinctly marginate on vertex. Occipital corners indicated by faint tubercular swellings on each side. Occipital border slightly convex. Cheeks immarginate below. Eyes flat. A distinct emargination extends from beneath the eyes back to the occipital corner. Upper surface of head finely punctate, with sparse, small foveolae, in which no distinct hair is visible. Foveolae slightly larger and more crowded on occiput, still larger, containing a distinctly visible, decumbent seta, on the lower surface of the head.

Thorax subfulgid above. Anterior border arcuate, shoulders subangulate. Sides of pronotum, with a strong lateral tooth, pointing obliquely forward. Transverse pronotal keel distinct, not sharply crested. Posterior corner of pronotum projecting in the form of a small rectangular tooth. In profile, the promesonotum is strongly convex. Promesonotal suture vestigial. Mesonotum with a stout, bluntly rounded, slightly upturned, marginate, lateral lobe. Thorax greatly constricted laterad between mesonotum and epinotum. Mesoepinotal suture impressed. Epinotum opaque. Basal face transverse with an anterolateral, broad, obtuse tooth, and a much stronger, greatly diverging posterior spine, with blunt apex, and a postero-ventral lamella, which does not border the declivity laterad. Declivous face longitudinally striatorugose. Microsculpture of promesonotum as on head, epinotum and sides subopaque, reticulate-puncate. Upper surface of thorax foveolate, sparsely on the anterior portion of the pronotum, densely and deeply behind, the foveolae being much larger than those of the upper surface of head. Laterotergite of pronotum with sparse and more shallow foveolae.

Petiole opaque; transverse with a stout, short, subacute, somewhat recurved lateral tooth. Posterior half shallowly transversely concave. Postpetiole slightly longer than petiole, as wide as petiole, with a p late-like, apically subtruncate apical tooth on each side. Both segments finely reticulate-punctate.

Gaster subopaque; elongate, the anterior border emarginate mesad, anterolaterally strongly marginate, without a distinct lamellate border. Sides subparallel, scarcely convex. Tergites and sternites finely reticulate-punctate, without foveolae.

All foveolae, except the ones on the upper surface of head and promesonotum, bear a decumbent, flattened seta. Setae rather shiny on epinotum. Gaster with minute, shiny, scalelike scattered hairs. Erect pile confined to the terminal tergites and sternites of gaster and the posterior half of the first sternite.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 5.30-6.92; HL 1.48-1.84; HW 1.60-1.80; EL 0.42-0.44; PW 1.30-1.64; PeW 0.66-0.78; PpW 0.60-0.74; HBaL 0.40-0.46; HBaW 0.10-0.12; CI 97.6-108.1; PI 109.7-123.1; PPeI 185.7-212.1; PPpI 216.7-233.1; HBaI 25.0-27.6.

Queen

de Andrade and Baroni Urbani (1999) - Head convex and without disc. Frontal carinae curved, reaching the anterior border of the eyes and converging posteriorly. Vertexal angles subround. Ocelli broad and deeply impressed. Eyes large and little convex, their anterior border making an anterior ridge delimiting the frontal carinae posteriorly. Clypeus ventrally prominent with the head in full dorsal view, emarginate in the middle of the anterior border, without lateral teeth. Mandibles broad, without lateral carina. Cheeks not carinate.

Mesosoma flat in side view. Humeral angles with.a short, pointed anterior tooth. Pronotal carina narrow; in some specimens interrupted on the sides. Mesonotum and scutellum flat. Lower mesopleura with a pointed denticle. Basal face of propodeum with two pairs of teeth; those of the anterior pair angulate or round, smaller and broader than those of the posterior one; the second pair between the basal and declivous faces and with pointed tips.

Petiole differentiated in anterior and posterior faces; anterior face almost vertical; posterior face gently sloping backwards. Petiolar sides with a minute. Postpetiole broadly convex on the middle; postpetiolar spines placed anteriorly, broad, with truncate tip directed laterally.

Gaster anteriorly protruding and with a simple margin not reaching the first stigma.

Legs. Fore coxae with a broad lobe anteriorly. Mid and hind femora not angulate. Hind basitarsi slightly flat and without broad base.

Wings. Fore wings with R +Sc superficially connected to a marked pterostigma; 2r marked, Rsf5 connected with Rl; distal parts of A, Cu-Al and Mf4 vestigial. Hind wings with R, M+CuA, M and 1A marked; CuA, M and distal part of lA vestigial.

Sculpture. Head, mesosoma and pedicel superficially reticulate-punctate and covered by foveae. Head dorsum with small, well impressed foveae with their interspaces broader than their maximum diameter, shallower and sparser on the frontal carinae. Ventral part of the head, anterior half of the pronotum, mesonotum and propleurae with foveae larger than those on the head dorsum. Posterior half of the pronotum and scutellum with foveae denser than those on the mesonotum. Propodeum, except the two posterior thirds, upper mesopleurae and pedicel with deep, contiguous foveae, more superficial on the pedicel. Lower mesopleurae and metapleurae with sparse, superficial foveae. Lower metapleurae punctate and with few longitudinal rugosities. Two posterior thirds of the declivous face of the propodeum punctate and with superficial transversal rugosities. Gaster and legs reticulate-punctate, with minute, superficial foveae on the gaster only.

Pilosity. Each fovea bears an appressed, canaliculate hair. Mesosoma, pedicel, gaster and legs with erect, slightly clavate hairs, rarer on the mesosoma and pedicel, sparse on the gaster.

Colour. Black with lighter gaster and proximal part of the femora. Distal part of the femora and remaining parts of the legs light brown. Gaster with two broad pairs of yellow spots, one on the gastral lobes, and the other on the posterior sides of the first tergite.

Measurements (in mm) and indices: TL 8.16-9.44; HL 1.52-1.68; HW 1.52-1.74; EL 0.42-0.47; PW 1.36-1.56; PeW 0.64-0.75; PpW 0.84-0.97; HBaL 0.51-0.55; HBaW 0.14-0.15; CI 100.0-106.1; PI 107.9-113.5; PPeI 187.6-233.8; PPpI 156.7-175.8; HBaI 25.4-27.4.

Male

de Andrade and Baroni Urbani (1999) - Head (eyes included) more than 1 /3 broader than long. Vertexal angles with an irregular margin with or without an obtuse medial tooth. Vertex dorsally protruding, bearing salient ocelli. Compound eyes broadly convex, at mid head length. Frontal carinae very short and diverging backwards. Frons flat. Clypeus convex posteriorly and with bidentate anterior border. Mandibles short, without external carina. Scapes thick, twice as long as the first funicular joint; remaining funicular joints thickening from the base to the apex.

Mesosoma. Pronotum in dorsal view with the sides diverging backwards. Humeral angles with or without a pair of denticles of variable size. Mesonotum convex in side view; median Mayrian furrow variably impressed but always present. Scutellum convex, rounded posteriorly. Basal and declivous faces of the propodeum differentiate; basal face gently convex; declivous face with converging sides.

Petiole with truncate anterior face; posterior face sloping posteriorly. Petiolar sides either unarmed or with a pair of small median denticles. Postpetiole convex and subhexagonal dorsally; its sides with a small, pointed or round median denticle.

Gaster as broad as the mesosoma.

Sculpture. Head dorsum minutely reticulate and irregularly rugose; this sculpture superimposed to superficial, variably clumped, irregular foveae on the vertexal area and frons. Ventral part of the head reticulate and with irregular foveae larger than those on the head dorsum. Pronotum, mesonotum, pro- and mesopleurae superficially reticulate-punctate and with few, very superficial and small foveae; scutellum reticulate and with foveae as on the mesonotum. Metapleurae and propodeum reticulate and with thin, longitudinal rugosities. Pedicel reticulate and with superficial, irregular foveae superimposed to weak, longitudinal rugosities on the sides only. First gastral tergite minutely reticulate; remaining tergites, sternites and legs superficially reticulate and weakly shining.

Pilosity. Body with long, thin, flexuous, pointed, golden hairs, dense on the head, on the mesosoma and on the pedicel, sparser on the gaster and on the femora. Gaster and legs with similar hairs but shorter, appressed on the tergites, decumbent on the sternites and on the femora. Tibiae and tarsi with short, pointed hairs.

Colour. Dark brown to black with lighter gaster. Coxae, proximal third to half of femora, tarsi dark ferrugineous to hrown, remaining parts of the legs yellow.

Measurements (in mm) and indices: TL 5.64-6.00; HL 0.84; HW 1.04-1.08; EL 0.39-0.41; PW 0.88-0.92; PeW 0.52-0.54; PpW 0.60-0.68; HBaL 0.58-0.63; HBaW 0.09-0.10; CI 123.8-128.6; PI 113.0-122.7; PPeI 169.2-170.4; PPpI 139.4-146.7; HBaI 15.5-15.9.

Type Material

The following notes on F. Smith type specimens have been provided by Barry Bolton (details):

Cryptocerus exiguus

Presence of the holotype in Oxford University Museum of Natural History has been confirmed by W.W. Kempf.

de Andrade and Baroni Urbani (1999):

Worker. Type locality "in America meridionali", actually Essequibo (Guyana). Type material: 2 syntype workers in Zoologisk Museum, University of Copenhagen (Zimsen, 1964: 427) (examined), only one of which labelled "Essequibo, Smidt, Mus. de Sehestedt, Cryptocerus minutus Fabr.".

Cryptocerus quadrimaculatus. Gyne. Type locality: Para (Brazil). Type material: not available for the present study. Synonymy by Emery, 1890: 74.

Formica caustica Kollar, 1832, in Pohl & Kollar, 1832: 17. Worker. Type locality: Brazil. Type material: not available for the present study.

Cryptocerus cognatus. Gyne. Type locality: Ega (= Tefe), Amazonas (Brazil). Type material holotype gyne (unique) labeled "Ega, Amazon." in The Natural History Museum, examined.

Cryptocerus exiguous. Worker. Type locality: Mexico. Type material: holotype worker (unique) labelled "Mex., Cryptocerus exiguus. Sm. Trans. Ent. Soc." in Oxford University Museum of Natural History (Type Hymenoptera 1044) (Kempf, 1958b), examined.

Cryptocerus volxemi. Worker. Type locality: Brazil. Type material: holotype worker labelled "Coll. Camille Van Volxem, Volxemi, Emery, Brasil" in Museo Civico di Storia Naturale, Genoa, examined.

References

  • de Andrade, M. L.; Baroni Urbani, C. 1999. Diversity and adaptation in the ant genus Cephalotes, past and present. Stuttgarter Beitrage zur Naturkunde Series B (Geolgie and Palaontologie). 271:1-889. (page 194, Combination in Cephalotes; page 195, Senior synonym of cognatus)
  • Emery, C. 1890b. Voyage de M. E. Simon au Venezuela (Décembre 1887 - Avril 1888). Formicides. Ann. Soc. Entomol. Fr. (6)(10): 55-76 (page 74, queen described; page 68, Senior synonym of quadrimaculatus and volxemi)
  • Emery, C. 1890c. Studii sulle formiche della fauna neotropica. Bull. Soc. Entomol. Ital. 22: 38-80 (page 74, Senior synonym of quadrimaculatus and volxemi)
  • Emery, C. 1915g. Noms de sous-genres et de genres proposés pour la sous-famille des Myrmicinae. Modifications à la classification de ce groupe (Hymenoptera Formicidae). Bull. Soc. Entomol. Fr. 1915: 189-192 (page 192, Combination in Cryptocerus (Paracryptocerus))
  • Fabricius, J. C. 1804. Systema Piezatorum secundum ordines, genera, species, adjectis synonymis, locis, observationibus, descriptionibus. Brunswick: C. Reichard, xiv + 15-439 + 30 pp. (page 420, worker described)
  • Gillette, P. N., K. K. Ennis, G. D. Martinez, and S. M. Philpott. 2015. Changes in Species Richness, Abundance, and Composition of Arboreal Twig-nesting Ants Along an Elevational Gradient in Coffee Landscapes. Biotropica. 47:712-722. doi:10.1111/btp.12263
  • Kempf, W. W. 1951. A taxonomic study on the ant tribe Cephalotini (Hymenoptera: Formicidae). Rev. Entomol. (Rio J.) 22: 1-244 (page 169, Combination in Paracryptocerus)
  • Kempf, W. W. 1958a. New studies of the ant tribe Cephalotini (Hym. Formicidae). Stud. Entomol. (n.s.) 1: 1-168 (page 110, Senior synonym of exiguus)
  • Koch, E. B. A., W. Dattilo, F. Camarota, and H. L. Vasconcelos. 2018. From species to individuals: does the variation in ant-plant networks scale result in structural and functional changes? Population Ecology. 60:309-318. doi:10.1007/s10144-018-0634-5
  • Kugler, C. 1978a. A comparative study of the myrmicine sting apparatus (Hymenoptera, Formicidae). Stud. Entomol. 20: 413-548 (page 474, Combination in Zacryptocerus)
  • Schmid V.S., Langner S., Steiner J. and Zillikens A. 2014. Inflorescences of the Bromeliad Vriesea friburgensis as Nest Sites and Food Resources for Ants and Other Arthropods in Brazil. Psyche. 2014:Article ID 396095. 9 pp. doi:10.1155/2014/396095
  • Smith, F. 1862d. A list of the genera and species belonging to the family Cryptoceridae, with descriptions of new species; also a list of the species of the genus Echinopla. Trans. Entomol. Soc. Lond. (3) 1: 407-416 (page 409, soldier described)
  • Wheeler, G. C.; Wheeler, J. 1954b. The ant larvae of the myrmicine tribes Cataulacini and Cephalotini. J. Wash. Acad. Sci. 44: 149-157 (page 155, larva described)