Cephalotes grandinosus

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Cephalotes grandinosus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. grandinosus
Binomial name
Cephalotes grandinosus
(Smith, F., 1860)

Cephalotes grandinosus casent0173699 profile 1.jpg

Cephalotes grandinosus casent0173699 dorsal 1.jpg

Specimen labels

Synonyms

Specimens have been collected in forest and at the edge of a river. Little else is known about the biology of Cephalotes grandinosus.

Identification

A member of the grandinosus clade characterised in the worker, soldier and gyne by the large and irregular foveae on the head; in the worker only by the flat gastral lamellae and by the mesonotum with two pairs of teeth. The worker, soldier and gyne of C. grandinosus are separate from the similar Cephalotes persimilis and Cephalotes persimplex by the broader and irregular foveae on the head dorsum. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Costa Rica, Panama, Colombia, Venezuela, Trinidad, Guyana, Brazil and Bolivia.

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality), Colombia, Costa Rica, Ecuador, Guyana, Panama, Trinidad and Tobago.

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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.

  • grandinosus. Cryptocerus grandinosus Smith, F. 1860c: 76, pl. 4, fig. 5 (w.) BRAZIL. Emery, 1894c: 219 (s.q.). Combination in Cryptocerus (Cyathocephalus): Santschi, 1919f: 47; in Paracryptocerus (Harnedia): Kempf, 1952: 11; in Zacryptocerus: Brandão, 1991: 386; in Cephalotes: De Andrade & Baroni Urbani, 1999: 433. Junior synonym of pinelii: Emery, 1890b: 75; Forel, 1895b: 134. Revived from synonymy: Luederwaldt, 1918: 41. Senior synonym of nevadensis: Kempf, 1952: 11.
  • nevadensis. Cryptocerus grandinosus var. nevadensis Forel, 1912e: 202 (w.) COLOMBIA. Junior synonym of grandinosus: Kempf, 1952: 11.

Description

Worker

de Andrade and Baroni Urbani (1999) - Head subquadrate; frons convex in the middle. Frontal carinae crenulate, covering large part of the mandibles and upturned above the eyes. Vertexal angles membranaceous, with a developed, round margin converging and narrowing before the middle of the vertexal border. Mandibles with a lateral carina visible in side view.

Mesosoma gently convex. Scapular angles absent or not visible in dorsal view. Anterior pronotal border straight; pronotal sides with a broad membranaceous expansion, anteriorly obtuse and narrowing posteriorly. Promesonotal suture superficially impressed in some specimens only. Mesonotum with two pairs of triangular, membranaceous teeth, the anterior pair longer, thicker and broader than the posterior one. Propodeal suture impressed. Declivous face of the propodeum gently sloping backwards. Basal and declivous propodeal faces with a broad membranaceous expansion starting from the anterior part of the basal face and strongly projected anteriorly, almost reaching the mesonotal spines forwards and broadening backwards; margin of the membranaceous expansion of the propodeum minutely crenulate and beset with minute hairs.

Petiole with a concave anterior face bearing laterally a pair of obtuse denticles; postpetiolar dorsum sloping anteriorly. Sides of the petiole with a broad, wing-shaped, membranaceous expansion with obtuse tip. Postpetiole slightly convex dorsally; postpetiolar sides with another broad, wing-shaped, membranaceous expansion with obtuse tip.

Gaster oval. First gastral tergite anterolaterally with a broad, flat, membranaceous expansion surpassing the stigma.

Mid and hind femora angulate; hind femora with two membranaceous crests on the two distal thirds, one on the dorsal face and another on the ventral face; mid femora with a narrow membranaceous crest dorsally and with a crest as high as the one on the hind femora ventrally. Mid and hind basitarsi flat and with slightly broad base.

Sculpture. Head dorsum punctate, with dense, large, irregular foveae diminishing in size and less impressed anteriorly. Frontal carinae punctate, with faint, sparse, superficial foveae. Ventral face of the head reticulate and with thin, superficial, longitudinal rugosities. Mesosoma punctate, with irregular foveae superimposed by longitudinal, slightly irregular rugosities. Pedicel with the same type of sculpture as the mesonotum but the foveae smaller and the rugosities thinner. Gaster strongly reticulate and with thin, longitudinal rugosities. Legs reticulate. Membranaceous expansions of mesosoma, pedicel and gaster punctate.

Pilosity. Each fovea with a decumbent hair; similar hairs but not originating from the foveae on the membranaceous expansions of the body. Legs and gaster with appressed hairs slightly thinner than the hairs originating from the foveae, sparser on the sternites. Membranaceous expansions of the propodeum with minute hairs originating from the crenulation. Frontal carinae with sparse, clubbed hairs. Gastral tergites and sternites with slightly clubbed, suberect hairs, denser on the sternites. The gastral sternites bear, in addition, a few long, thin, slightly pointed hairs.

Colour. Body light brown. Frontal carinae opaque, yellow. Membranaceous expansions whitish and semi-transparent. Tarsi brown.

Measurements (in mm) and indices: TL 2.52-4.12 HL 0.66-0.96; HW 0.70-1.10; EL 0.22-0.29; PW 0.60-1.00; PeW 0.37-0.60; PpW 0.37-0.64; HBaL 0.19-0.33; HBaW 0.05-0.11; CI 106.1-116.5; PI 110.0-119.3; PPeI 148.2-166.7; PPpI 148.2-162.2; HBaI 26.3-33.3.

Soldier

de Andrade and Baroni Urbani (1999) - Head disc subquadrate, with differentiate, strongly crenulate and raised border; sides of the disc gently broadening anteriorly and partially covering the eyes. Posterior border of the disc with a pair of small denticles in some specimens only. Floor of the disc flat to gently convex in the middle. Vertexal angles subround, completely separate from the disc and with marked, crenulate border. Mandibles laterally carinate and partially hidden by the frontal carinae.

Mesosoma. Anterior pronotal border convex. Humeral angles with an obtuse, membranaceous expansion with the sides gently converging posteriorly up to the middle of the pronotum where it continues into the pronotal carina. Posterior half of the pronotal sides strongly converging. Pronotal carina high, divided in two halves by an incision, each half posteriorly convex and diminishing in height towards the middle of the pronotum. Pronotal suture variably impressed. Promesonotal suture deeply impressed. Mesonotal sides with a pair of broad, triangular, obtuse or pointed teeth followed by a pair of short, thin, pointed, membranaceous denticles. Propodeum with differentiate basal and declivous faces; sides of the basal face with a narrow, crenulate, membranaceous expansion forming cranially a pair of obtuse teeth directed anterolaterally and followed by a convexity converging posteriorly into a pair of small denticles. Declivous face of the propodeum narrowing posteriorly and with membranaceous expansion.

Petiole with concave anterior face; wing-shaped membranaceous expansions with obtuse or pointed tips arise laterally on the two anterior thirds of the petiole. Postpetiole gently convex dorsally, with similar wing-like lateral expansions as the petiole but directed anteriorly and with round tip.

Gaster oval. First gastral tergite anterolaterally with a pair of broad membranaceous expansions not reaching the stigma posteriorly.

Legs as in the worker but with the crest on the dorsal face of the mid and hind femora narrower.

Sculpture. Head dorsum punctate and covered by large, deep, irregular foveae diminishing in size anteriorly. Ventral face of the head reticulate and with superficial foveae denser on the sides. Mesosoma with the same type of sculpture as on the head dorsum, but less deep. Propleurae reticulate and with sparse, broad, superficial foveae. Pedicel and mesopleurae reticulate and with foveae smaller than those on the mesosoma. Declivous face of the propodeum, metapleurae, gaster and legs reticulate. Declivous face of the propodeum, lower metapleurae and anterior third of the first gastral segmental with longitudinal, thin rugae. Center of the first gastral sternite moderately shining.

Pilosity. Each fovea with a suberect clubbed hair. Legs and gaster with appressed, clubbed hairs thinner and shorter than the hairs originating from the foveae, sparser on the sternites. Gaster with erect, short, clubbed hairs, denser on the sternites. Frontal carinae, vertexal angles, mesosoma, pedicel and the border of the tergites and sternites with long, sparse, clubbed hairs. The sternites bear, in addition, a few long, thin, slightly pointed hairs.

Colour. As in the worker.

Measurements (in mm) and indices: TL 5.04-5.44; HL 1.20; HW 1.32-1.36; EL 0.28; PW 1.36; PeW 0.60-0.66; PpW 0.65-0.69; HBaL 0.28-0.30; HBaW 0.11-0.12; CI 110.0-113.3; PI 97.0-100.0; PPeI 206.1-226.7; PPpl 197.1-209.2; HBaI 39.3-40.0.

Queen

de Andrade and Baroni Urbani (1999) - Head disc present. Head dorsum gently convex with concave anterolateral sides. Frontal carinae strongly crenulate, expanded anteriorly, converging posteriorly and connected by a slightly convex, crenulate ridge on the vertex. Vertex with a depression reaching the posterior border of the disc. Vertexal angles obtuse and with crenulate margin. Eyes visible in full dorsal view. Ocelli remote from the posterior border of the disc. Anterior clypeal border concave. Mandibles with a lateral carina and partially hidden by the frontal carinae.

Mesosoma. Anterior pronotal border gently convex. Humeral angles with a pair of small, obtuse, membranaceous teeth converging posteriorly and connected to a narrow pronotal crest. Pronotal sides straight caudally to the angles. Promesonotal suture impressed. Lower mesopleurae with a denticle. Mesonotum and scutellum flat. Propodeum with differentiate basal and declivous faces; sides of the basal face gently convex and ending in a obtuse or pointed tooth posteriorly; declivous face converging posteriorly and with a narrow membranaceous border on the posterior half.

Petiole with gently concave anterior face; sides of the petiole with a small membranaceous expansion with obtuse or pointed tip. Postpetiole convex dorsally; postpetiolar sides with a broad, round, lateral expansion directed anteriorly.

Gaster. First gastral tergite anterolaterally with a pair of broad lobes with a thin membranaceous expansion not reaching the stigma posteriorly.

Legs as in the soldier but with the dorsal face of the mid femora superficially carinate.

Sculpture and pilosity as in the soldier.

Colour. Light brown. Frontal carinae yellowish-opaque and semitransparent. Tarsi brown. First gastral tergite with a pair of dark brown maculae on the middle of the dorsum, superficially connected medially in some specimens.

Measurements (in mm) and indices: TL 6.96-7.08; HL 1.28-1.32; HW 1.28-1.30; EL 0.32; PW 1.24-1.32; PeW 0.61; PpW 0.68-0.76; HBaL 0.41-0.44; HBaW 0.14; CI 98.5-100.0; PI 98.5-103 .2; PPeI 203.3-216.4; PPpI 163.1-194.1; HBaI 31.8-34.1.

Type Material

de Andrade and Baroni Urbani (1999) :

Worker. Type locality: Ega (= Tefe) (Amazonas, Brazil). Type material: holotype worker labelled “59 10” in The Natural History Museum, examined.

Cryptocerus grandinosus var. nevadensis. Worker. Original description. Type locality (restricted in the present study): Burithaca (written "Burithaka" by hand of Forel on the label, not located) (Sierra Nevada de Santa Marta, Colombia), listed first, not Belem (Para, Brazil), listed second, misidentification. Type material: one syntype worker from Burithaca in Musee d'Histoire Naturelle Genève (examined). The Brazilian syntype from Belem belongs to another species to be described for Cephalotes persimilis.

References

  • Brandão, C. R. F. 1991. Adendos ao catálogo abreviado das formigas da região Neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412 (page 386, 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 433, Combination in Cephalotes)
  • Emery, C. 1890b. Voyage de M. E. Simon au Venezuela (Décembre 1887 - Avril 1888). Formicides. Ann. Soc. Entomol. Fr. (6)(10): 55-76 (page 75, Junior synonym of pinelii)
  • Emery, C. 1894d. Studi sulle formiche della fauna neotropica. VI-XVI. Bull. Soc. Entomol. Ital. 26: 137-241 (page 219, soldier, queen described)
  • Forel, A. 1895b. A fauna das formigas do Brazil. Bol. Mus. Para. Hist. Nat. Ethnogr. 1: 89-139 (page 134, Junior synonym of pinelii)
  • Kempf, W. W. 1952. A synopsis of the pinelii-complex in the genus Paracryptocerus (Hym. Formicidae). Stud. Entomol. 1: 1-30 (page 11, Combination in Paracryptocerus, page 11, Senior synonym of nevadensis)
  • Luederwaldt, H. 1918. Notas myrmecologicas. Rev. Mus. Paul. 10: 29-64 (page 41, Revived from synonymy)
  • Santschi, F. 1919f. Nouveaux formicides de la République Argentine. An. Soc. Cient. Argent. 87: 37-57 (page 47, Combination in Cryptocerus (Cyathocephalus))
  • Smith, F. 1860c. Descriptions of new genera and species of exotic Hymenoptera. J. Entomol. 1: 65-84 (page 76, pl. 4, fig. 5 worker described)