Cephalotes bruchi

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Cephalotes bruchi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. bruchi
Binomial name
Cephalotes bruchi
(Forel, 1912)

Cephalotes bruchi casent0173666 profile 1.jpg Cephalotes bruchi casent0173666 dorsal 1.jpg Specimen labels

Synonyms

Specimens have been collected from fallen a fallen mature Parapiptadenia rigida tree in a botanical garden in Asuncion, Paraguay. Little else is known about the biology of Cephalotes bruchi.

Identification

A member of a clade of its own (bruchi clade) which, in addition to the synapomorphies already discussed in the clade description, is easily recognisable by the following combination of characters: in the worker frontal carinae strongly upturned above the eyes and gaster with a pair of solid, broad and protruding lobes; in the soldier and gyne by the incomplete disc, by the postpetiole with broad expansions pointed backwards and by the pronotal carina superficial or absent laterally. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Argentina and Mato Grosso, Brazil.

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina (type locality), Brazil, Ecuador.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

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

Nomenclature

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

  • bruchi. Cryptocerus bruchi Forel, 1912e: 202 (w.) ARGENTINA. Combination in Paracryptocerus: Kusnezov, 1953b: 338; in Zacryptocerus: Brandão, 1991: 385; in Cephalotes: Baroni Urbani, 1998: 326; De Andrade & Baroni Urbani, 1999: 618. Senior synonym of pampaensis, ridiculus: Kempf, 1958a: 44.
  • ridiculus. Cryptocerus ridiculus Santschi, 1915b: 207, fig. 1 (s.) ARGENTINA. Bruch, 1917b: 269 (q.). Junior synonym of bruchi: Kempf, 1958a: 44.
  • pampaensis. Cryptocerus (Cryptocerus) iheringi st. pampaensis Santschi, 1931e: 277 (s.w.) ARGENTINA. Junior synonym of bruchi: Kempf, 1958a: 44.

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

Description

Worker

Kempf (1958) - Total length 5.1-6.0 mm; maximum length of head 1.35-1.61 mm; of thorax 1.61-1.82 mm (lectotype measurements: 5.9, 1.53, 1.82). Measurements of a single worker-soldier intermediate: 6.8, 1.75, 2.02 mm. Black; frontal carinae pale testaceous; tip of scape, and apical tarsites fuscous-ferruginous.

Head subopaque, subquadrate, its maximum length usually scarcely shorter, sometimes longer, than the interocular width. Mandibles rugulose. Frontal carinae semitransparent, their lateral border scarcely crenulate, nearly straight-edged, and conspicuously diverging caudad. Sides of head strongly upturned into a perpendicular position, forming on the inside a longitudinal furrow starting at some distance in front of the eyes and reaching back to the occipital lobes, which are obliquely truncate, with the edge sometimes slightly notched and bearing on the inner corner a strong, opaque, flat, triangular tooth. Eyes bulging, considerably convex, their greatest diameter less than one fourth of the maximum head length. Occipital border concave. Upper face of head gently and evenly convex discad, finely reticulate-punctate, more sparsely covered with squamiferous foveolae. Lower face of head reticulate-rugose discally.

Thorax subopaque. Anterior border gently arcuate. Shoulders subdentate. Sides of pronotum with a tridentate, sharply marginate border, converging caudad. The anteriormost tooth of this border acute and large, the second tooth obtuse, the third subrectangular. Promesonotal suture obsolete. Mesonotum with a blunt, tuberculate tooth on each side. Mesoepinotal suture usually, not always, distinct and slightly impressed. Epinotum sharply marginate on each side, the anterior corner of basal face forming an obtuse tooth followed by a larger, triangular platelike tooth. Declivous face continuous with the basal face, both forming, in profile, an almost even curvature. Dorsum of thorax finely reticulate-punctate, rather densely covered with somewhat elongate squamiferous foveolae. A few very short longitudinal costulae on the anterior border of epinotum in specimens that show a distinct mesoepinotal suture. The lower half of the laterotergite of pronotum longitudinally striate. The greater part of the thoracic pleura more or less longitudinally reticulate-rugose.

Peduncular segments subopaque, the dorso-lateral sculpture as on thorax. Petiole scarcely narrower than postpetiole, its anterior face obliquely truncate, finely reticulate-punctate and slightly shining, lacking all kind of macro sculpture and pilosity. Anterior corners of petiole rounded, continued laterally by a stout, strongly recurved, sharply pointed lateral spine. Postpetiole with slightly concave anterior border, bearing on each side an even more strongly recurved and pointed spine, resembling a pigeon wing. Upper face of postpetiole convex, often vestigially acuminate discally.

Gaster short, oval, rather shining, its median length usually scarcely exceeding the maximum width, deeply excised antero-mesally, between the submarginate, strongly projecting anterolateral gastral lobes. First tergite finely reticulate-punctate, with sparse piligerous punctures.

Standing hair confined to the apex and venter of gaster. Scalelike hair of head and thorax and peduncle canaliculate and appressed; of gaster simple, thin, but appressed.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 5.76-6.28; HL 1.32-1.46; HW 1.46-1.68; EL 0.34-0.36; PW 1.16-1.42; PeW 0.60-0.66; PpW 0.64-0.70; HBaL 0.60-0.72; HBaW 0.17-0.20; CI 110.6-123.5; PI 118.3-125.8; PPeI 206.0-243.3; PPpI 202.8-228.1; HBal 27.8-28.6.

Soldier

Kempf (1958) - Total length 8.4-10.6 mm; maximum length of head 2.39-3.10 mm; of thorax 2.50-2.96 mm. Black; anterolateral corners of head to a variable extent fuscous yellowish-red; tip of scape, apical funicular segments, extensor face of tibiae and apical tarsites fuscous-ferrugineous.

Head shining, subquadrate, little or scarcely broader than long, without a distinct, completely marginate disc above. Anterolateral borders vestigially crenulate, posterior border sharply marginate above the truncate occiput, postero-lateral border of upper face immarginate, i.e. the disc surface is continuous with the occipital lobes. Dorsum of head scarcely convex, almost flat, slightly excavated anterolaterally above the antennal scrobes. Clypeal sutures and midfrontal suture well marked, the latter extending beyond the middle of head. Occipital lobes terminating in a stout, solid tooth. Eyes little convex. Lower border of cheeks carinate. Upper face of head and sides finely punctate, with sparse squamiferous, roundcd foveolae, separated from each other by a distance which exceeds their own diameter. Lower face of head foveolate. Cheeks and mandibles reticulate-rugose and foveolate.

Thorax less shining than head. Pronotum nearly as broad as head, its anterior angle with a stout tooth, which is blunt at apex. Sides of pronotum gently sinuous, gently converging caudad, the posterior corner rounded. Transverse pronotal carina bisinuate, bluntly edged, interrupted in the middle. Promesonotal suture vestigial. Lateral lobes of mesonotum obliquely truncate, immarginate. Mesoepinotal suture distinct and impressed. Basal face of epinotum with a little projecting, broad, rounded lobe on each side, and a stronger, apically rounded tooth on the posterior corner, projecting upward and obliquely laterad. Declivous face about twice as long as basal face, slightly excavated discally, immarginate at the sides. Sculpture of dorsum of thorax as on upper face of head, the microsculpture being a bit stronger, and the foveolae more crowded. Sides of thorax with more elongate foveolae, and a reticulate-rugose area on the posterior half. Middle and hind basitarsi slightly broadened and flattened at base.

Peduncular segments subopaque, the dorso-lateral sculpture as on dorsum of thorax. Postpetiole distinctly broader than petiole. Lateral spines of both segments equally recurved, their apices not very acute.

Gaster rather short, oval, subopaque, its greatest width at the middle of its length. Shallowly emarginate antero-mesally, the anterolateral lobes much less projecting than in worker. First tergite finely, but sharply and densely punctate, with sparse, piligerous punctures.

Scalelike hair in the foveolae, as a rule, short and inconspicuous, especially on head, more visible and longer on pronotum and sides of thorax. Very small and simple on first gastral tergite. Standing hair, as usual, in this caste, confined to the tip and venter of gaster.

de Andrade and Baroni Urbani (1999) - Measurements (in mm) and indices: TL 9.66-10.56; HL 2.30-2.60; HW 2.60-3.08; EL 0.42-0.48; PW 2.44-2.84; PeW 0.92-1.08; PpW 1.02-1.16; HBaL 0.70-0.72; HBaW 0.21-0.24; CI 113.0-118.5; PI 106.5-108.4; PPeI 262.9-265.2; PPpI 239.2-244.8; HBaI 30.0-33.3.

Queen

de Andrade and Baroni Urbani (1999):

(translation of the description of Bruch, 1917). – “Long, 11 millimetres. With the same colour as the soldier, i. e. black, the anterior part of the head, the antennae and the legs brown-reddish.

Moderately shining; the abdomen is more opaque, due to the presence on its surface of a reticulate punctuation, more pronounced than over the head and the thorax. The latter are covered by large points or small pits slightly larger over the head and which are at the same time larger than in the soldier, but smaller and less deep on the abdomen. Each pit carries a flattened hair, short and decumbent, much thinner on the abdomen, which has also a few setae on its extremity.

The head is square, as in the soldier, slightly smaller (2.5 x 2.5 mm); its sides are also parallel, the posterior angles straight, the borders slightly sinuous and not crenulate; it exists also a weak spine in the lower third of the posterior border. The ocelli, arranged in a regular triangle, are slightly larger than the size of the small pits.

The thorax is half longer than broad (3.1 x 2.2 mm); all narrower than the one of the soldier. The lateral teeth of the epinotum are narrower. The two peduncular nodes are slightly longer, the first is weakly toothed laterally; the second, i.e. the postpetiole as in the soldier. The abdomen is twice longer than broad, cylindrical and also strongly notched at the base.

Width of the pronotum 2.2 mm, of the epinotum 1.2 mm, of the abdomen 2.2 mm; length of the thorax 3 .2 mm, of the abdomen 5 mm.”

Measurements (in mm) and indices: TL 12.20-12.62; HL 2.24-2.28; HW 2.48-2.56; EL 0.45-0.48; PW 2.28-2.52; PeW 0.88-0.92; PpW 1.08-1.16; HBaL 0.83-0.88; HBaW 0.24-0.25; CI 110.7-112.3; PI 101.6-108.8; PPeI 259.1-273.9; PPpI 211.1-217.2; HBaI 28.4-28.9.

Type Material

de Andrade and Baroni Urbani (1999):

Worker. Type locality: Huasan (Catamarca, Argentina). Type material: lectotype worker (implicitly designated by Kempf, 1958 b) in Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Buenos Aires (not available for the present study), 2 workers (syntypes) labelled "Huasan, 1300 m, Argentina, 3.2.1912, C. Bruch, “in einen Vogelnest 4 Stuck", in Musee d'Histoire Naturelle Genève, examined.

Cryptocerus ridiculus. Soldier. Type locality: Chaco de Santiago (Argentina). Type material: holotype (unique) labelled “Argentina, Chaco de Santiago del Estero - Rio Salado, collection Wagner” in Naturhistorisches Museum, Basel, examined.

Cryptocerus jheringi pampaensis. Worker and soldier. Type locality: Monte Nievas (Argentina). Type material 1 worker, 1 soldier and 1 incomplete soldier labelled “Monte Nievas, Pampa, J. Belsak” in Naturhistorisches Museum, Basel, examined.

References

  • Baroni Urbani, C. 1998b. The number of castes in ants, where major is smaller than minor and queens wear the shield of the soldiers. Insectes Soc. 45: 315-333 (page 326, Combination in Cephalotes)
  • Brandão, C. R. F. 1991. Adendos ao catálogo abreviado das formigas da região Neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412 (page 385, Combination in zacryptocerus)
  • 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 618, Combination in Cephalotes)
  • Forel, A. 1912f. Formicides néotropiques. Part II. 3me sous-famille Myrmicinae Lep. (Attini, Dacetii, Cryptocerini). Mém. Soc. Entomol. Belg. 19: 179-209 (page 202, worker described)
  • Kempf, W. W. 1958a. New studies of the ant tribe Cephalotini (Hym. Formicidae). Stud. Entomol. (n.s.) 1: 1-168 (page 44, Senior synonym of pampaensis and ridiculus)
  • Kusnezov, N. 1953c. Lista de las hormigas de Tucumán con descripción de dos nuevos géneros (Hymenoptera, Formicidae). Acta Zool. Lilloana 13: 327-339 (page 338, Combination in Paracryptocerus)