Cephalotes insularis

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Cephalotes insularis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. insularis
Binomial name
Cephalotes insularis
(Wheeler, W.M., 1934)

De Andrade 1999 Cephalotes OCR - Copy-586 Cephalotes-insularis.jpg

Nothing is known about the biology of Cephalotes insularis.

Identification

A member of the wheeleri clade differing from its sister species, Cephalotes hirsutus, by the shorter and sparser appressed hairs of the worker. Both share the postpetiolar spines almost as long as the postpetiole and the border of the first gastral tergite yellowish and transparent. Some of the workers intercepted in Nogales present a pair of distinct brownish spots on the anterior face of the gaster; other specimens from the same series don't. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Mexico (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.

  • insularis. Cryptocerus pilosus subsp. insularis Wheeler, W.M. 1934f: 140 (w.) MEXICO. Combination in Paracryptocerus (Harnedia): Kempf, 1958a: 128; in Zacryptocerus: Brandão, 1991: 386; in Cephalotes: De Andrade & Baroni Urbani, 1999: 583. Raised to species: Kempf, 1958a: 128.

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

Description

Worker

de Andrade and Baroni Urbani (1999) - Vertexal angles round, with superficially crenulate border. Vertexal border straight and variably marginate medially. Hypostoma not connected by a bridge. Cheeks superficially marginate dorsally. Frontal carinae with a superficial notch over the eyes. Antennal scrobes reaching the antero-ventral border of the eyes. Clypeal border concave. Mandibles with faint lateral carinae.

Mesosoma convex in side view. Pronotum in dorsal view with the anterior border not marginate and convex. Scapular angles absent or not visible in dorsal view. Pronotum with a narrow lamellae bearing three pairs of lateral teeth, the first, humeral, short and pointed, followed by another subequal in length or smaller, variably pointed and by a third broad, obtuse or slightly pointed pair close to the mesonotum. Sides of the mesonotum converging posteriorly and unarmed. Promesonotal and propodeal sutures in dorsal view superficially marked in some specimens only, more impressed on the sides. Propodeum declivous, without distinctly differentiated basal and declivous faces, with a pointed, thin spine directed laterally and slightly upwards at midlength.

Petiole anteriorly truncate; its anterior border marked by a transversal carina variably marked. Petiolar spines ca. half so long as the length of the petiole, thin, pointed backwards and on the middle of the petiolar sides. Postpetiole broader than petiole, with thin, pointed spines slightly shorter than the postpetiolar length, arising anterolaterally and curved backwards at the base.

Gaster oval, without crest, lobe or lateral margin.

Hind and mid femora without angle or denticles; mid and hind basitarsi long and without flat and broad base.

Sculpture. Head dorsum reticulate, with irregular, superficial foveae separated by broad reticulation. Frontal carinae superficially reticulate. Ventral face of the head irregularly striata-rugose and reticulate, the reticulation more impressed in larger specimens. Mesosoma minutely reticulate, irregularly foveolate, the foveae separated by broad reticulation forming longitudinal rugae on the posterior half of the pronotum and on the propodeum; in small specimens the foveae less evident. Same sculpture but more superficial on the pedicel. Sides of the mesosoma with the same sculpture as on the dorsum, but with few or without striae on the upper meso- and metapleurae. First gastral tergite and sides of the first gastral sternite with longitudinal, thin rugosities, irregular and less impressed on the middle of the posterior half of the first gastral tergite in some specimens. Anterolateral borders of the first gastral tergite and central part of the first sternite superficially reticulate and shining. Legs reticulate, with slightly shining femora. Distal part of the outer face of the femora and outer face of the tibiae with oval and superficial foveae.

Pilosity. Body with four types of hairs: (1) sparse, long, erect and truncate on the head, on the mesosoma, on the pedicel, on the gastral tergites and on the legs; (2) similar to the type (1) but thinner and shorter on the sternites; (3) canaliculate, appressed, thick, denser on the vertexal border, on the mesosoma and on the pedicel; (4) similar hairs to the type (3) but shorter and thinner on the frons, on the gaster and on the legs.

Colour. Dark brown to black. Frontal carinae yellowish to light ferruginous and semitransparent. Legs orange or ferruginous or light brown with darker basitarsi. Border of the first gastral tergite yellowish and transparent. Some specimens with the anterolateral border of the first gastral tergite with a pair of oval, orange-reddish spots. Vertexal angles, propodeum and pedicel with weak golden reflexes.

Measurements (in mm) and indices: TL 4.08-4.94; HL 1.00-1.20; HW 1.04-1.32; EL 0.28-0.33; PW 0.88-1.18; PeW 0.56-0.62; PpW 0.68-0.74; HBaL 0.44-0.48; HBaW 0.09-0.10; CI 104.0-111.1; PI 111.8-118.2; PPeI 157.1-190.3; PPpI 129.4-159.4; HBaI 20.4-20.8.

Soldier

de Andrade and Baroni Urbani (1999) - Head disc present. Head dorsum concave, the concavity increasing anteriorly. Middle of the head dorsum with a broad tumulus. Frontal carinae broadly expanded anteriorly, not covering the eyes, strongly converging posteriorly and connected by a sharp, straight ridge on the vertex. Vertexal angles round and marginate. Eyes moderately convex. Clypeal border deeply concave anteriorly. Mandibles laterally carinate and largely hidden by the frontal carinae.

Mesosoma. Humeral angles with a broad, angulate tooth anteriorly, their sides converging posteriorly. Pronotal carina marked and interrupted in the middle. Promesonotal suture impressed. Mesonotal sides with a broad tooth with round or pointed tip. Lower mesopleurae without denticles. Propodeum differentiated in basal and declivous faces; basal face in dorsal view poorly convex, with a broad, pointed tooth in the middle of each side and narrowing towards the declivous face; declivous face longitudinally concave.

Petiole with distinctly differentiated anterior and posterior faces; anterior face truncate, posterior face slightly convex and bearing, on its sides, a pointed spine directed backwards. Postpetiole broadly convex; postpetiolar spines broad, pointed, arising from the anterior border of the postpetiole and slightly curved backwards.

Gaster with a barely protruding anterior border and laterally not marginate.

Legs. Fore coxae with a tumulus anteriorly. Mid and hind femora without angle or denticles. Mid and hind basitarsi without broad base and not compressed laterally.

Sculpture. Head and mesosoma reticulate-punctate, with superimposed foveae broader than their interspaces, diminishing in size on the anterior part of the head and more superficial on the frontal carinae. Pedicel reticulate and with dense foveae, in some specimens this sculpture extends to the sides of the mesosoma. Pleurae reticulate, superficially foveolate and with few rugosities, the foveae rare on the metapleurae. Two posterior thirds of the declivous face of the propodeum, gaster and legs reticulate, the reticulation fainter on the femora and on the posterior half of the first gastral sternite. Anterior third of the first gastral tergite with longitudinal rugosities; most specimens bear similar rugosities but more superficial on the sides or on the anterior third of the first gastral sternite. Outer face of the tibiae with oval and superficial foveae.

Pilosity. Body with four types of hairs: (1) decumbent to appressed arising from each fovea, longer and thicker on the propodeum, on the pedicel and on the lower part of the meso- and metapleurae, slightly shorter and thinner on the extensor face of the legs; (2) long, erect, truncate, rare on the pedicel, sparse on the first gastral tergite and on the legs, dense on the posterior border of the gaster; (3) similar to type (2) but shorter and thinner on the first gastral sternite; (4) minute, appressed and thin on the gaster and on the anterior and posterior faces of the legs.

Colour. Black. Frontal carinae dark red. Some specimens with the dorsal side of the head dark red. Legs ferruginous with brown tarsi. Some specimens with the antero-lateral border of the first gastral tergite with a pair of oval, reddish spots or with the border of the first gastral tergite yellowish and transparent.

Measurements (in mm) and indices: TL 6.60-6.84; HL 1.64-1.68; HW 1.76-1.84; EL 0.36-0.37; PW 1.80; PeW 0.71-0.74; PpW 0.80-0.88; HBaL 0.46-0.48; HBaW 0.13; CI 107.3-109.5; PI 97.7-102.2; PPeI 243.2-253.5; PPpI 204.5-225.0; HBaI 27.1-28.3.

Queen

de Andrade and Baroni Urbani (1999) - Head disc present. Posterior two thirds of the head dorsum gently convex. Anterior third of the head concave. Frontal carinae anteriorly broadly expanded and with raised border, converging posteriorly and connected by a convex carina on the vertex. Vertexal angles round and marginate. Eyes convex and not hidden by the disc in dorsal view. Anterior clypeal border concave. Mandibles with a lateral carina and partially hidden by the frontal carinae.

Mesosoma flat in side view. Humeral angles with an obtuse tooth anteriorly, straight posteriorly. Pronotal carina marked and superficially interrupted in the middle. Promesonotal suture impressed. Propodeum differentiated in basal and declivous face; basal face weakly convex dorsally, with the sides bearing a small denticle medially; sides of the declivous face converging posteriorly.

Petiole distinctly differentiated in anterior and posterior faces; anterior face truncate, posterior face slightly convex and with the sides bearing a minute denticle medially. Postpetiole broadly convex; postpetiolar spines broad, obtuse and arising from the anterior border of the postpetiole

Legs and gaster. As in the soldier.

Sculpture. Head, pronotum, mesonotum and scutellum reticulate-punctate and with foveae broader than their interspaces, slightly sparse on the middle of the mesopleurae and on the anterior half of the ventral part of the head Propodeum, upper mesopleurae and pedicel reticulate and with dense foveae. Propleurae and metapleurae reticulate and with sparse foveae on the propleurae and rare on the metapleurae. Two posterior thirds of the declivous face of the propodeum, gaster and legs reticulate, the reticulation fainter on the femora and on the posterior half of the first gastral sternite. Anterior third of the first gastral tergite with longitudinal rugosities; similar rugosities but more superficial on the sides of the anterior third of the first gastral sternite. Outer face of the tibiae with oval and superficial foveae.

Pilosity. As in the soldier except for the presence hair type (2) on the border of the frontal carinae and of the vertexal angles and on the mesosoma.

Colour. Head reddish, gaster darker. Mesosoma and pedicel dark brown. Legs ferruginous with brown tarsi.

Measurements (in mm) and indices: TL 8.24; HL 1.68; HW 1.76; EL 0.39; PW 1.70; PeW 0.58; PpW 0.67; HBaL 0.53; HBaW 0.15; CI 104.8; PI 103.5; PPeI 293.1; PPpI 253.7; HBaI 25.9.

Type Material

de Andrade and Baroni Urbani (1999) - Worker. Type locality: Isla Maria Madre (Tres Marias group, Nayarit, Mexico). Type material: holotype lost, neotype worker from the Maria Magdalena Island (Tres Marias Group) in Los Angeles County Museum of Natural History (Snelling, 1968). Not seen.

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 583, Combination in Cephalotes)
  • Kempf, W. W. 1958a. New studies of the ant tribe Cephalotini (Hym. Formicidae). Stud. Entomol. (n.s.) 1: 1-168 (page 128, Combination in Paracryptocerus (Harnedia), Raised to species)
  • Wheeler, W. M. 1934f. Ants from the islands off the west coast of Lower California and Mexico. Pan-Pac. Entomol. 10: 132-144 (page 140, worker described)