Difference between revisions of "Cephalotes pallens"

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*''[[Cryptocerus araneolus]]'' Smith, F., 1853
 
*''[[Cryptocerus araneolus]]'' Smith, F., 1853
 
*''[[Cryptocerus discocephalus]]'' Smith, F., 1853
 
*''[[Cryptocerus discocephalus]]'' Smith, F., 1853
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''Cephalotes pallens'' is one of the more commonly encountered species in the genus. It appears to be relatively flexible in its choice of nesting site (dead sticks, hollow vines, etc.) and can be found in a variety of habitats.
 
''Cephalotes pallens'' is one of the more commonly encountered species in the genus. It appears to be relatively flexible in its choice of nesting site (dead sticks, hollow vines, etc.) and can be found in a variety of habitats.
 
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{{At a Glance
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|Item1 = Phragmotic
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|Link1 = Phragmosis
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==Identification==
 
==Identification==
 
A member of the [[Cephalotes_Species_Groups#pallens_clade |''pallens'' clade]] differing from its sister species, ''[[Cephalotes porrasi]]'', by the following apomorphies: in the worker propodeal expansions incised posteriorly, hind femora crested and HBaI > 38, in the soldier and gyne, hind femora carinate and head disc with canaliculate hairs. The concavity on the membranaceous expansions of the worker propodeum is much more impressed in small workers than in the larger ones; some small workers may bear another, superficial, anterior notch. This variation makes the small workers of ''pallens'' appear more similar to ''porrasi'' than the large ones. Large workers tend to have the propodeal incision less deep and even almost inexistent in a few cases. (de Andrade and Baroni Urbani 1999)
 
A member of the [[Cephalotes_Species_Groups#pallens_clade |''pallens'' clade]] differing from its sister species, ''[[Cephalotes porrasi]]'', by the following apomorphies: in the worker propodeal expansions incised posteriorly, hind femora crested and HBaI > 38, in the soldier and gyne, hind femora carinate and head disc with canaliculate hairs. The concavity on the membranaceous expansions of the worker propodeum is much more impressed in small workers than in the larger ones; some small workers may bear another, superficial, anterior notch. This variation makes the small workers of ''pallens'' appear more similar to ''porrasi'' than the large ones. Large workers tend to have the propodeal incision less deep and even almost inexistent in a few cases. (de Andrade and Baroni Urbani 1999)

Latest revision as of 17:30, 13 July 2019

Cephalotes pallens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Cephalotes
Species: C. pallens
Binomial name
Cephalotes pallens
(Klug, 1824)
Synonyms

Cephalotes pallens P casent0217840.jpg

Cephalotes pallens D casent0217840.jpg

Specimen Label

Cephalotes pallens is one of the more commonly encountered species in the genus. It appears to be relatively flexible in its choice of nesting site (dead sticks, hollow vines, etc.) and can be found in a variety of habitats.

At a Glance • Phragmotic  

 

Identification

A member of the pallens clade differing from its sister species, Cephalotes porrasi, by the following apomorphies: in the worker propodeal expansions incised posteriorly, hind femora crested and HBaI > 38, in the soldier and gyne, hind femora carinate and head disc with canaliculate hairs. The concavity on the membranaceous expansions of the worker propodeum is much more impressed in small workers than in the larger ones; some small workers may bear another, superficial, anterior notch. This variation makes the small workers of pallens appear more similar to porrasi than the large ones. Large workers tend to have the propodeal incision less deep and even almost inexistent in a few cases. (de Andrade and Baroni Urbani 1999)

Keys including this Species

Distribution

Mexico to and through northern South America, including islands off the northern coast and the southernmost Lesser Antilles.

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality), Colombia, Costa Rica, Ecuador, French Guiana, Grenada, Guatemala, Guyana, Honduras, Lesser Antilles, Mexico, Nicaragua, Panama, Peru, Suriname, Trinidad and Tobago, Venezuela.

Distribution based on AntMaps

AntMapLegend.png

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.

Morphology

Wheeler and Holldobler (1985) investigated how Cepholates workers might collect or accumulate debri on their head disks. Such debri can be used as camouflage for individuals that are using their head to block the nest entrance, much like Basicerotini and Stegomyrmicini ant species affix dirt their bodies. They discovered Cephalotes pallens do in fact have encrusted material on their head disks. This varied from slight to extremely built-up material. Unexpectedly these covering materials appeared to be produced by the ants, rather than an accumulation of material that was affixed and somehow binded to the head disk. The presence of many pores, which are presumably attached to glands, are the likely source of secreted fibrous and filmy substances that were detected.

They also discovered: "Z. pallens (Figs. 4-6). To the eye, the head of the soldier shown in Fig. 4a appeared to be covered with a thin layer of dirt. Closer examination revealed that the surface was covered with irregular ribbons of material (Figs. 4b, 5a). Pores were visible along part of the central ridge (see Fig. 5b). Material seemed to be extruded in lumpy strands from a number of the pores (Figs. 5b, 6), supporting the suggestion that it is secretory in origin."

Castes

Nomenclature

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

  • pallens. Cryptocerus pallens Klug, 1824: 206 (w.) BRAZIL. Emery, 1894c: 212 (s.q.); Emery, 1896h: 635 (m.); Wheeler, G.C. & Wheeler, J. 1973b: 79 (l.). Combination in Cryptocerus (Cyathocephalus): Emery, 1915i: 192; in Cryptocerus (Cyathomyrmex): Creighton, 1933: 100; in Zacryptocerus: Brandão, 1991: 387; in Cephalotes: De Andrade & Baroni Urbani, 1999: 493. Senior synonym of araneolus, discocephalus: Emery, 1894c: 212; Kempf, 1958a: 151.
  • araneolus. Cryptocerus araneolus Smith, F. 1853: 223, pl. 19, fig. 4 (w.) ANTILLES. Subspecies of discocephalus: Forel, 1893g: 382. Revived status as species: Forel, 1897b: 300. Subspecies of pallens: Forel, 1899c: 51. Junior synonym of pallens: Emery, 1894c: 212; Kempf, 1958a: 151.
  • discocephalus. Cryptocerus discocephalus Smith, F. 1853: 222, pl. 20, fig. 2 (w.) BRAZIL. Smith, F. 1858b: 191 (s.m.); Smith, F. 1876d: 608 (q.). Combination in Cryptocerus (Cyathocephalus): Emery, 1924d: 311. Subspecies of pallens: Forel, 1911e: 257. Junior synonym of pallens: Emery, 1894c: 212; Kempf, 1958a: 151.

Description

Worker

de Andrade and Baroni Urbani (1999) - Similar to the other species of the group from which it differs for one or more of the following characters. Head broader than long. Frontal carinae with weakly crenulate border. Membranaceous expansions of the vertexal angles variably developed. Pronotum with a pair of broad, membranaceous expansions. Mesonotum with a pair of triangular or subrectangular semimembranaceous teeth. Propodeum with a pair of broad, membranaceous expansions, covering and fused with two-three small teeth and with a deep posterior notch posteriorly less incised among large specimens. Anterior border of the petiole with a pair of salient swellings. Petiolar sides with a pair of pointed spines as long as or longer than the petiole. Postpetiolar sides with a pair of pointed spines directed slightly forwards . Gaster suboval and with a pair of anterolateral membranaceous expansions surpassing the stigma posteriorly and continuing up to the posterior border of the first tergite as a superficial margin. Hind and mid femora angulate; mid femora dorsally carinate; hind femora dorsally with a developed longitudinal crest.

Sculpture. Head dorsum and mesosoma minutely reticulate-punctate, with dense foveae, smaller on and behind the clypeus, sparser, shallower and irregular on the frontal carinae. Frontal carinae with additional, oblique, thin rugosities. Ventral part of the head reticulate; some specimens with longitudinal rugosities on the two anterior thirds. Pedicel minutely reticulate-punctate and with small, irregular foveae. Pleurae strongly reticulate and with few, thin, longitudinal rugosities; in some specimens the rugosities denser and more impressed. First gastral tergite reticulate; its sides with superficial, irregular foveae separate by few, thin, irregular, longitudinal rugosities extending to the anterior third in some specimens. Remaining gastral tergites and sternites simply reticulate, with the sides of the first gastral sternites superficially foveolate-rugulose in some specimens only; center of the first gastral sternites with less impressed reticulation and superficially shining. Legs strongly reticulate and with minute, superficial, irregular foveae, more impressed and denser on the outer face of the tibiae.

Pilosity. Body foveae with appressed hairs. Posterior part of the frontal carinae in front of the eyes, vertexal angles, posterior border of the gastral tergites, and legs with rare, clubbed hairs. Gastral sternites with two types of pointed hairs: (1) sparse and short, and (2) rare and long on the second gastral sternite only. Body parts without foveae with sparse, appressed, thin, short hairs.

Colour. Brown to black with the frontal carinae and the membranaceous expansions of the body slightly lighter.

Measurements (in mm) and indices: TL 3.73-5.38; HL 0.88-1.16; HW 0.98-1.40; EL 0.20-0.30; PW 0.84-1.22; PeW 0.64-0.83; PpW 0.54-0.81; HBaL 0.24-0.34; HBaW 0.10-0.13; CI 108.9-120.7; PI 111.4-117.8; PPeI 115.7-162.7; PPpI 143.3-166.7; HBaI 38.2-45.8.

Soldier

de Andrade and Baroni Urbani (1999) - Head disc suboval, longer than broad. Border of the disc strongly raised and with superficially crenulate margin posteriorly, the crenulation stronger in small specimens. Floor of the disc medially with a gently convex tumulus. Posterior part of the disc variably depressed.

Mesosoma. Humeral angles with a pair of obtuse, semi-membranaceous teeth. Pronotal sides straight or gently converging posteriorly. Pronotal carina well marked, with variably crenulate margin and shortly interrupted medially. Mesonotal sides with a pair of broad, triangular or round teeth. Propodeum with differentiate basal and declivous faces; basal face almost as broad as the mesonotum; sides of the basal face convex or diverging backwards into a small pair of irregular teeth followed by a pair of short, stout teeth curved upwards in large specimens.

Pedicel as in the worker but with narrower and shorter spines.

Mid and hind femora angulate; hind femora carinate.

Gaster oval and with a pair of protruding anterior lobes with marked margins.

Sculpture. Head dorsum with sparse and shallow foveae, the fovea rare on the anterior half, rarely denser and deeper on the whole disc; this morphology is more frequent among small specimens. Interspaces between the foveae porous. Sides of the disc densely and irregularly foveolate-rugulose, the foveae diminishing in size anteriorly, sometimes with superimposed longitudinal rugosities. Ventral part of the head punctate, variably shining and covered by small foveae and irregular rugosities superficial in the center, more longitudinal posterolaterally and more transversal anterolaterally. Mesosoma minutely reticulate-punctate and with dense foveae less regular and shallower on the middle of the mesonotum and on the basal face of the propodeum of some specimens, larger on the pronotum, smaller on the propodeum. Pedicel minutely reticulate-punctate and with small, irregular foveae. Pleurae strongly reticulate; propleurae variably foveolate-rugose, the rugae oblique to transversal. Lower parts of the meso- and of the metapleurae with longitudinal rugosities and small foveae; some specimens either simply rugose or foveolate only. Gaster and legs with sculpture similar to that of the worker.

Pilosity. The foveae on the head dorsum with a subdecumbent to appressed, canaliculate hair; those on the mesosoma, pedicel, gaster and legs with an appressed one. Borders of the disc and foveae on the sides of the head with erect, long, variably clavate hairs. Vertexal angles, pronotum, pedicel, first gastral tergite, posterior borders of the remaining tergites and sternites and legs with rare, clubbed hairs. Gastral sternites, in addition, with two types of pointed hairs: (1) sparse and short, and (2) rare and long on the second and on the third gastral sternites. Body parts without foveae with sparse, appressed, thin, short hairs.

Colour. Dark brown to black.

Measurements (in mm) and indices: TL 5.16-7.72; HL 1.36-1.96; HW 1.28-2.00; EL 0.27-0.36; PW 1.22-1.84; PeW 0.61-0.89; PpW 0.57-0.83; HBaL 0.24-0.36; HBaW 0.12-0.15; CI 89.5-94.1; PI 101.2-108.7; PPeI 187.7-217.9; PPpI 213.3-221.7; HBaI 40.6-50.0.

Queen

de Andrade and Baroni Urbani (1999) - Differing from the soldier in the following details.

Sides of the disc with less raised borders. Posterior border of the disc much more crenulate. Maximum disc concavity usually anterior. Humeral angles with a pair of small, triangular teeth or simply obtuse. Pronotal carina lower. Pronotum, mesonotum and scutellum flat in side view. Sides of the basal face of the propodeum anteriorly convex or triangular and posteriorly with a small pair of pointed teeth, slightly diverging laterally.

Petiole with oblique anterior face; its sides with a small pair of denticles. Postpetiole convex dorsally and with a pair of round or pointed teeth pointed backwards.

Gaster. Similar to the one of the soldier but much longer and with more protruding lobes.

Legs with less salient carinae of the mid and hind femora.

Sculpture. Foveae of the head dorsum denser, larger and deeper than in the soldier. Mesonotal foveae shallower. Propodeal foveae deeper. Pleurae reticulate. Propleurae with foveae on the upper part and with thin, oblique to longitudinal rugosities on the lower part. Upper and center of the lower mesopleurae foveolate, the foveae deeper and denser on the upper part. Metapleurae with longitudinal rugosities on the lower part and with small foveae on the upper border. Occasionally the anterior third of the first gastral tergite with deeper foveae and rugae.

Pilosity. As in the soldier except for the hairs of the disc, suberect to subdecumbent, and for the clubbed hairs more abundant on the pedicel, on the gaster and on the legs and extending to the whole mesosoma.

Colour. Dark brown to black.

Measurements (in mm) and indices: TL 8.00-8.28; HL 1.64-1.76; HW 1.52-1.60; EL 0.38-0.39; PW 1.44-1.56; PeW 0.55-0.65; PpW 0.70-0.77; HBaL 0.40-0.43; HBaW 0.16-0.17; CI 87.5-92.7; PI 102.6-106.9; PPeI 240.0-261.8; PPpI 194.6-205.7; HBaI 37.2-42.5.

Male

de Andrade and Baroni Urbani (1999) - Similar to the other species of the group from which it differs for one or more of the following characters. Frontal carinae not raised. Clypeus convex posteriorly and straight anteriorly. Pronotum in dorsal view with traces of scapular angles.

Sculpture. Head dorsum minutely reticulate and irregularly foveolate-rugose on its posterior third. Frons with rare, minute foveae. Remaining dorsal surfaces of the head with thin rugosities, transversal close to the eyes and longitudinal between the ocelli. Ventral part of the head reticulate and with irregular, oblique rugae. Pronotum minutely reticulate and with small, superficial foveae, deeper on the sides. Mesonotum with minute, superficial reticulation and with small, faint, sparse, foveae. Scutellum similarly sculptured and with thin, longitudinal rugosities. Basal face of the propodeum reticulate and with irregular, lon gitudinal rugosities. Propleurae reticulate, sometimes with few, longitudinal, thin rugosities. Mesopleurae superficially reticulate and with thin, longitudinal rugosities on the posterior half; this sculpture covered by few, superficial, small foveae on the center of the mesopleurae. Metapleurae reticulate and irregularly rugose, the rugosities more longitudinal on the lower part. Pedicel with superficial and minute reticulation and with few, short rugosities on the sides. Gaster superficially reticulate and slightly shining. Legs punctate with moderately shining femora.

Pilosity as for the other species of the group.

Colour. Black. Pedicel, coxae and gaster brown. Legs dark yellow with slightly darker tarsomeres.

Measurements (in mm) and indices: TL 4.18-4.47; HL 0.65-0.72; HW 0.85-0.90; EL 0.34-0.39; PW 0.72-0.80; PeW 0.31; PpW 0.36; HBaL 0.43-0.52; HBaW 0.06-0.07; CI 125.0-130.8; PI 112.5-118.0; PPeI 232.2; PPpI 200.0; HBaI 13.2-13.9.

Type Material

de Andrade and Baroni Urbani (1999):

Worker. Type locality: Brazil. Type material: not available for the present study.

Cryptocerus discocephalus Soldier. Type locality: Villa Nova (Brazil). Type material presumably lost, neither in The Natural History Museum nor in Oxford University Museum of Natural History.

Cryptocerus araneolus Worker. Type locality: Antille St. Vincent. Type material: holotype worker labelled "St. Vincts" in the The Natural History Museum, examined

References

  • Brandão, C. R. F. 1991. Adendos ao catálogo abreviado das formigas da região Neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412 (page 387, Combination in Zacryptocerus)
  • Creighton, W. S. 1933. Cyathomyrmex, a new name for the subgenus Cyathocephalus Emery. Psyche (Camb.) 40: 98-100 (page 100, Combination in Cryptocerus (Cyathomyrmex))
  • 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 493, Combination in Cephalotes)
  • Emery, C. 1894d. Studi sulle formiche della fauna neotropica. VI-XVI. Bull. Soc. Entomol. Ital. 26: 137-241 (page 212, soldier, queen described, Senior synonym of araneolus and discocephalus)
  • Emery, C. 1896h. Formiciden, gesammelt in Paraguay von Dr. J. Bohls. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 9: 625-638 (page 635, male described)
  • 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 (Cyathocephalus))
  • Kempf, W. W. 1958a. New studies of the ant tribe Cephalotini (Hym. Formicidae). Stud. Entomol. (n.s.) 1: 1-168 (page 151, Senior synonym of araneolus and discocephalus)
  • Klug, F. 1824. Entomologische Monographien. Berlin: Reimer, 242 pp. (page 206, worker described)
  • Wheeler, D. E.; Hölldobler, B. 1986 ("1985"). Cryptic phragmosis: the structural modifications. Psyche (Cambridge) 92:337-353. [1986-04-27] PDF
  • Wheeler, G. C.; Wheeler, J. 1973b. Ant larvae of four tribes: second supplement (Hymenoptera: Formicidae: Myrmicinae). Psyche (Camb.) 80: 70-82 (page 79, larva described)