Cephalotes pileini

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Cephalotes pileini
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. pileini
Binomial name
Cephalotes pileini
De Andrade, 1999

Cephalotes pileini P casent0904924.jpg

Cephalotes pileini D casent0904924.jpg

Specimen Label

Nothing is known about the biology of Cephalotes pileini.

Identification

A member of the pinelii clade differing from its outgroup species, Cephalotes nilpiei, and from its ingroup species Cephalotes pinelii, in the worker, by the head longer than the pronotal width, and, from the soldier of nilpiei and pinelii, by the floor of the disc less concave and by the absence of propodeal teeth. All the Argentinean workers from La Carlota and described here as pileini differ from those of pinelii (known only from Paraguay and Brazil) by the head and gaster much longer, by the membranaceous expansions of the mesosoma narrower, and by the foveae much denser and irregular. The soldiers and gynes of pileini differ from those of pinelii by the vertexal groove shallower, by the border of the frontal carinae less crenulate, by the hairs on the frontal carinae sparser, by the foveae less impressed and by the pronotal crest very reduced in the soldier and absent in the gyne. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina (type locality).

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.

  • pileini. Cephalotes pileini De Andrade, in De Andrade & Baroni Urbani, 1999: 385, figs. 171, 172 (s.w.q.) ARGENTINA.

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

Description

Worker

Head subquadrate with convex frons. Frontal carinae covering the mandibles proximally and slightly upturned above the eyes Vertexal angles round, with a thin, membranaceous margin converging and narrowing before the middle of the vertexal border. Mandibles with thick lateral carina.

Mesosoma gently convex. Scapular angles absent or not visible in dorsal view. Anterior border of the pronotum convex in dorsal view; pronotal sides with a membranaceous expansion anteriorly obtuse and narrowing posteriorly. Promesonotal suture, in dorsal view, superficially impressed on the sides only. Mesonotum with a pair of pointed or obtuse, membranaceous teeth. Propodeal suture impressed. Declivous face of the propodeum gently sloping backwards. Basal and declivous propodeal faces with a membranaceous lateral expansion originating from the propodeal suture.

Anterior face of the petiole medially concave; dorsal face gently convex. Sides of the petiole with a wing-shaped, membranaceous expansion with round tip and directed laterally. Postpetiole convex dorsally; postpetiolar sides also with a wing-shaped, membranaceous expansion with round tip.

Gaster oval and elongate. First gastral tergite anterolaterally with a broad membranaceous expansion.

Legs. Mid and hind femora dorsally angulate and with a carina on the distal part of their dorsum. Mid and hind basitarsi compressed at the base.

Sculpture. Head dorsum minutely reticulate, with dense foveae diminishing in size anteriorly. Ventral face of the head reticulate and with superficial, dense foveae forming longitudinal rugosities anteriorly. Mesosoma and pedicel reticulate, with irregular, dense foveae forming longitudinal, irregular rugosities, the foveae smaller on the propodeum and on the pedicel. Gaster and legs deeply reticulate. First gastral tergite with thin, longitudinal rugosities on the anterior third, the rugosities becoming thinner and more superficial posteriorly. Membranaceous expansions of mesosoma, pedicel and gaster reticulate, the latter with few, thin, longitudinal rugosities anteriorly.

Pilosity. Each fovea with an appressed hair; similar hairs but not originating from the foveae and slightly thinner 6n the membranaceous expansions, on the gaster and on the legs. Posterior border of the gastral segments with rare, erect, clubbed hairs.

Colour. Dark brown with lighter legs. Frontal carinae orange and semi-transparent. Membranaceous expansions of the body yellowish and semi-transparent. First gastral tergite anterolaterally with an orange, long, thin strip directed posteriorly. Some specimens with the head darker than the rest of the body.

Measurements (in mm) and indices: TL 3.55-4.44; HL 0.86-0.96; HW 0.93-1.06; EL 0.24-0.25; PW 0.79-0.89; PeW 0.54-0.61; PpW 0.53-0.63; HBaL 0.25; HBaW 0.10; CI 108.1-110.4; PI 117.7-117.8; PPeI 146.3-147.5; PPpI 142.8-149.0; HBal 40.0.

Soldier

Head disc subround, with differentiated border and raised more on the sides than posteriorly. Sides of the disc not covering completely the eyes and broadening anteriorly. Floor of the disc concave and with a small tumulus in the middle. Vertex with a superficial depression.

Vertexal angles round, completely separate from the disc and with superficially crenulate border. Mandibles laterally carinate and laterally hidden by the frontal carinae.

Mesosoma. Anterior pronotal border gently convex. Humeral angles with a narrow, obtuse, lateral, membranaceous expansion converging posteriorly up to the middle of the pronotum where it continues into the poorly marked pronotal carina. Posterior half of the pronotal sides strongly converging posteriorly. Pronotal suture in dorsal view impressed on the sides. Promesonotal suture deeply impressed. Mesonotal sides with two pairs of teeth, the anterior pair broad, and with truncate tips, the posterior pair small, thin and pointed. Propodeum with differentiate basal and declivous faces; sides of the basal face convex, with the posterior half bearing a narrow membranaceous expansion extending and broadening up to the end of the declivous face.

Pedicel as in the worker but with the expansions less broad.

Legs as in the worker but with the dorsal carina less impressed.

Gaster oval, with a margin not reaching the stigma posteriorly.

Sculpture. Head dorsum, mesosoma and pedicel reticulate-punctate and covered by dense foveae, smaller and shallower on the border of the disc and on the clypeus, on the propodeum and on the pedicel. Ventral face of the head reticulate and with irregular, superficial foveae and irregular rugosities. Declivous face of the propodeum reticulate and with thin, longitudinal rugae. Gaster and legs strongly reticulate and with superficial, minute foveae. First gastral tergite with thin, longitudinal rugosities on the anterior third, less impressed and irregular posteriorly.

Pilosity. Each fovea with an appressed hair. Legs and gaster with appressed hairs thinner and shorter than those originating from the foveae. Border of the disc over the eyes, and posterior border of the gastral segments with rare clubbed hairs. The sternites bear, in addition a few long, thin, slightly pointed hairs.

Colour. Dark brown with the sides of the mesonotum, of the pedicel and of the first gastral tergite with a lighter strip.

Measurements (in mm) and indices: TL 5.14-5.40; HL 1.20-1.26; HW 1.32-1.36; EL 0.25-0.28; PW 1.28-1.32; PeW 0.64-0.65; PpW 0.67-0.69; HBaL 0.27; HBaW 0.12; CI 107.9-110.0; PI 103.0-103.1; PPeI 200.0-203.1; PPpI 185.5-197.0; HBal 44.4.

Queen

Head disc present. Head dorsum gently convex posteriorly and with concave anterolateral sides. Frontal carinae superficially crenulate, expanded anteriorly, converging posteriorly and connected by a convex carina on the vertex. Vertex between the pair ocelli with a superficial depression. Vertexal angles round and with marked margin. Eyes visible in full dorsal view. Ocelli remote from the posterior border of the head disc. Anterior clypeal border deeply concave. Mandibles with a lateral carina and partially hidden by the frontal cannae.

Mesosoma. Anterior pronotal border gently convex. Humeral angles obtuse. Pronotal sides straight. Pronotal carina absent. Promesonotal suture impressed. Lower mesopleurae with a denticle. Mesonotum and scutellum flat. Propodeum with differentiate basal and declivous faces; sides of the basal face convex; declivous face converging posteriorly and with a narrow membranaceous border on the posterior half.

Petiolar sides convex and with marked margin. Postpetiolar sides with a round lobe directed anteriorly.

Gaster with a pair of broad, anteriorly protruding lobes.

Sculpture. Head dorsum reticulate and with dense foveae diminishing in size anteriorly and less impressed in the middle" of the frontal carinae. Mesosoma and pedicel with the same type of sculpture as on the anterior part of the head dorsum, but with sparser foveae on the middle of the mesonotum. Declivous face of the propodeum, gaster and legs as in the soldier.

Pilosity. As in the soldier.

Colour. Brown, floor of the disc darker. Frontal carinae orange and semi-transparent. Sides of the pronotum and of the propodeum yellowish. First gastral tergite with two pairs of yellowish spots, thc first pair anterolateral and the second one before the posterior border.

Measurements (in mm) and indices: TL 6.72-7.00; HL 1.26-1.32; HW 1.26-1.28; EL 0.31-0.32; PW 1.24; PeW 0.58; PpW 0.69-0.72; HBaL 0.40; HBaW 0.14; CI 97.0-100.0; PI 101.6-103.2; PPeI 213.8; PPpI 172.2-179.7; HBaI 35.0.

Paratype Specimen Labels

Type Material

Holotype: soldier, Argentina, Cordoba, La Carlota, Silvestri Museum of Comparative Zoology.

Paratypes: four workers and one gyne MCZ, one worker and one gyne Museo Civico di Storia Naturale, Genoa, one worker and one soldier Museu de Zoologia da Universidade de Sao Paulo, three workers and one soldier Naturhistorisches Museum, Basel, same data as the holotype.

Etymology

Pileini is an anagram of pinelii, the name of the species with which this species had been previously confused.

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 385, figs. 171, 172 soldier, worker, queen described)