Antonio José Mayhé-Nunes¹ & Adriana Maria Lanziotti ²

1 Departamento de Biologia Animal. Instituto de Biologia. Universidade Federal Rural do Rio de Janeiro. Seropédica, RJ, 23890-000, Brazil; amayhe@ufrrj.br

2 Curso de Pós-Graduação em Biologia Animal. Instituto de Biologia. Universidade Federal Rural do Rio de Janeiro. Seropédica, RJ, 23890-000, Brazil; alanziotti@bol.com.br

Received 20-IX-2001.       Corrected 30-VI-2002.      Accepted 20-VII-2002.

We describe the female and male of the Neotropical fungus-growing ant Mycetarotes carinatus, hitherto only known from type locality, Rio de Janeiro state, Brazil, based on samples of workers. The sexual forms were obtained from a nest maintained in the laboratory. The samples found in Minas Gerais state, expand the geographic distribution of the species. We illustrate the external architecture of the nest of M. carinatus.

Key words: Brazil, Attini, fungus-growing ant, nest, taxonomy.

The taxonomy of ants is usually based on the worker caste, described in about 92% of the total of catalogued species of Attini (Kempf 1972, Brandão 1991, Bolton 1995). However, nearly 46% of these ant species are only known from worker, with no record of sexual forms. Produced exclusively in periodical cycles, when leave their nests in nuptial flights for mating, males and females are found with lower frequency than workers, suggesting the necessity of more studies involving alates to fill this lacuna of knowledge. Concerning the genus Mycetarotes, just one species, M. parallelus, had female and male described, by Emery (1905) and Kempf (1961), respectively.

Mycetarotes carinatus was described based on workers from a county of Rio de Janeiro state (Mayhé-Nunes 1995). After the description was published we received a live nest with some males of this species from Minas Gerais state, collected by José Henrique Schoereder in the Campus of the Universidade Federal de Viçosa.

The nest was inside a secondary forest in clay soil on a human trail, and a single chamber was found at a shallow depth (Schoereder pers. com.). After six months in the laboratory we obtained more males and also females, described in this work. Moreover, this discovery expands the geographic distribution of M. carinatus, hitherto known only from type locality, and it was possible to remark on the unknown external architecture of its nest.

The descriptions of the ants were partially based on Emery (1905) and Kempf (1961), the first authors who described sexual forms of Mycetarotes. The terminology for the characters of the alitrunk was based on Wheeler (1925). Some terms needed modernization and we follow Hölldobler and Wilson (1990) and Bolton (1994).

The specimens examined were labeled as Viçosa, Mata da Biologia, MG, BRA, 2.iv.1996, J.H. Schoereder leg. ~700m alt. (#225 Mayhé’s notebook), and were deposited in the following Brazilian institutions: 10 males and 5 females in the CECL – Coleção Entomológica Angelo Moreira da Costa Lima (at the institution of the senior author); 2 males and 2 females in the MZSP - Museu de Zoologia da Universidade de São Paulo (São Paulo, SP); 1 male and 1 female in the MNRJ - Museu Nacional do Rio de Janeiro (Rio de Janeiro, RJ).

 Mycetarotes carinatus
Mayhé-Nunes, 1995 .
(Figs. 1-11)

Mycetarotes carinatus Mayhé-Nunes, 1995:200-202, fig. 3 a-b (worker; Brazil: Engenheiro Paulo de Frontin, Rio de Janeiro; key; nest).

Description of the female Measures (in mm): TL 3.1; HL 0.85; HW 0.88; DE 0.18; IFW 0.41; ScL 0.74; TrL 1.11; LFw 3.29; LHw 2.45. Body light brown, with head front slightly darker; inconspicuous and appressed minute hairs; integument finely granulated.

 Alitrunk: (Figs. 2 and 3) Pronotum with pair of strong and blunt humeral spines, out and forwards directed, and with pair of inferior spines down and forwards pointed, similar to the humeral ones. Scutum without notable large divisions; anterior margin with small notch and narrow and short furrow on each side; median posterior portion superficially impressed; parapsidial furrow visible in dorsal view, parapsis weakly excavate, with outer margin transformed into low ridge. Mesothoracic paraptera deeply impressed in middle, with rounded lateral margin. Scutellum with pair of longitudinal tubercles on each side, finishing posteriorly in pair of short and blunt spines. Metathoracic paraptera similar to those of male. Propodeum with rounded lateral margins in dorsal view and with pair of small tubercles, between basal and declivitous faces.

Waist and gaster: (Figs. 2 and 3) Dorsum of petiole with pair of blunt tubercles. Postpetiole broader than petiole, in dorsal view, shallowlly impressed above, with the posterior margin largely notched. First gastric tergite with four longitudinal ridges, the lateral ones matched with lateral margin of the sclerite.

Wings: (Figs. 4 and 5) Wings microscopically hairy and infuscated. Fore wing with four closed cells (sub-marginal, costal, median and submedian); marginal cell open. Pterostigma conspicuous. Hind wing with five veins, without closed cells; six hamuli on anterior margin.

Comments: The principal characters that separate the two hitherto known females of Mycetarotes are: (1) Presence of two anterior teeth of the occipital corners relatively more prominent than in M. parallelus. (2) Apical teeth of the mandibles similar in size to the sub-apical ones; longer in M. parallelus. (3) Head almost as long as broad; longer than broad in M. parallelus. (4) Pair of blunt dorsal projections on petiole; acute in M. parallelus. (5) Lateral margins of postpetiole without lateral expansions in dorsal view; in M. paral lelus laterally expanded on its posterior half. (6) Propodeum with a pair of small projections tubercle-like; prominent and strong spines in M. parallelus. (7) First gastric tergite with four longitudinal ridges; absent in M. parallelus.

Description of the male

Measures (in mm): TL 3.9; HL 0.65; HW 0.89; DE 0.34; IFW 0.21; ScL 0.62; TrL 1.38; LFw 2.98; LHw 2.07. The body is dark brown, with black head; inconspicuous and appressed minute hairs; integument finely reticulated, with rugulae on some parts of head and alitrunk.

Head: (Fig. 6) Mandible striated on dorsal surface and fully punctuated; masticatory margin with only two apical teeth; external margin straight with the apex curved inwards, with head in full-face view. Median margin of clypeus moderately convex, without anterior notch; surface of clypeus with two minute lateral tubercles, between anterior margin and base of frontal lobe, followed above, in the median region, by wide and transversally vaulted furrow. Frontal lobe laterally rounded and dorsally forwards pointed. Frontal carina short, rather straight, obliquely directed medially. Preocular carina curved above eye, not attaining the vertex. Compound eye very large and convex, occupying about 2/3 of the side of head. Ocelli inserted on short and cylindrical projections. Antenna with 13 segments; scape surpassing the occipital corner by nearly 1/4 of its length, longer than funicular segments I-III combined; funicular segment I slightly shorter than II. Occipital corners angulated with single tooth on each side. Occipital margin notched in the middle, between lateral ocelli.

Alitrunk: (Figs. 7 and 8) Pronotum with small humeral spine and tumuliform projection close to rounded inferior margin. Scutum with wide and deeply impressed Mayrian furrow separating three areas: an anterior prescutal and two lateral mesoscutal. Prescutum a little lower than mesoscutum, when in lateral view; parapsidial furrows on mesoscutum, visible in dorsal view; parapsis deeply excavated, with the outer margin transformed into high ridge. Mesothoracic paraptera narrowed and deeply impressed in middle, in dorsal view, with thick and blunt projection on each side. Scutellum surmounted by pair of longitudinal tubercles on each side, ending as two short, slender and blunt spines. Metathoracic paraptera concealed by scutellum in dorsal view. Propodeum with the lateral margins angulated in dorsal view and with pair of small projections, between basal and declivitous faces.

Wings: (Figs. 9 and 10) Wings microscopically hairy and infuscated. Fore wing with three closed cells (marginal, submarginal and costal); median and sub-median cells partially open. Pterostigma conspicuous. Hind wing with five veins, without closed cells; six hamuli on anterior margin.

The larger nest of M. carinatus (Fig. 11) observed in the Mata da Biologia has an external architecture very different from that described by Mayhé-Nunes (1995) for M. parallelus (Fig. 12). The entrance was in the bottom of a small crater-shaped mound, with nearly 6 cm of diameter at the base and 4 cm height; the other nest found in the area also had the same shape, but was smaller. In a third nest without mound, the same pattern found by Mayhé-Nunes (1995) to M. carinatus, the workers were following two opposite trails to put earth grains nearly 15 cm away from the entrance. The exuviae of a spider carried by a worker (deposited in CECL) was the only forage item observed in the field, but substrate discarded from the nest in the laboratory reveled that the items used to cultivated fungus in this species are similar to those of M. parallelus (seeds, woody decayed matter and insect feces). The maintenance of the laboratory nest was done with parts of Hibiscus flowers, manioc root flow and cotton soaked in water.

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This work is part of the research "Comparative Biology of Ants, Specially of the Tribe Attini", with a grant from Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq (301273/95-2), and financial support by Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro –FAPERJ (E-26/171.734/99). The Fundação de Amparo à Pesquisa do Estado de Minas Gerais - FAPEMIG (CAG1703/95) supported partially this work. We are also grateful to José Henrique Schoereder for the nest of Mycetarotes carinatus, and the three anonymous referees for helpful suggestions.

Describimos la hembra y el macho de la hormiga neotropical cultivadora de hongos, Mycetarotes carinatus, hasta ahora solo conocida de la localidad-tipo, con base en muestras de obreras. Las formas sexuales fueron obtenidas de un nido criado en laboratorio. Las muestras del estado de Minas Gerais, Brasil, amplían la distribución geográfica de la especie. Ilustramos la arquictetura externa del nido de M. carinatus.

Bolton, B. 1994. Identification Guide to the Ant Genera of the World. Harvard University, Cambridge, Massachusetts. 222 p.        [ Links ]

Bolton, B. 1995. A New General Catalogue of the Ants of the World. Harvard University, Cambridge, Massachusetts. 504 p.        [ Links ]

Brandão, C.R.F. 1991. Adendos ao Catálogo abreviado das Formigas da Região Neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.        [ Links ]

Emery, C. 1905. Studi sulle formiche della fauna neotropica. XXVI. Bull. Soc. Ent. Ital., 37: 107-194.        [ Links ]

Hölldobler, B. & E.O. Wilson. 1990. The Ants. Harvard University, Cambridge, Massachusetts. 732 p.        [ Links ]

Kempf, W.W. 1961. Review of the ant genus Mycetarotes Emery (Hymenoptera, Formicidae). Rev. Bras. Biol. 20: 277-283.        [ Links ]

Kempf, W.W. 1972. Catálogo abreviado das Formigas da Região Neotropical (Hym., Formicidae). Studia Entomol. 15: 3-344.        [ Links ]

Mayhé-Nunes, A.J. 1995. Sinopse do gênero Mycetarotes Emery (Hym., Formicidae), com a descrição de duas espécies novas. Bol. Entomol. Venez. 10: 197-205.        [ Links ]

Wheeler, W.W. 1925. Ants: their structure, behavior and development. Columbia University, New York. pp. 660.        [ Links ] ]]> 1994 222 1995 504 1991 35 319-412 1905 37 107-194 1990 1961 20 277-283 1972 15 3-344 1995 10 197-205 1925 660