Myrmicocrypta

A genus of fungus growing ants. Sosa-Calvo & Schultz (2010) - Myrmicocrypta is currently regarded as relatively “primitive” fungus growing genus, i.e., as retaining many character states considered plesiomorphic for the group, including characters of wing venation (Kusnezov 1963); male antennae (Kusnezov 1961); degree of queen/worker polymorphism (Wheeler 1910); monomorphism of the worker caste (Wheeler 1910, Emery 1912); larval morphology, including the form of the galea in some species and straight (rather than curved) body proÞle (Schultz and Meier 1995); position on the integument of mutualistic Pseudonocardia Henssen (Actinomycetes) bacterial symbionts (Currie et al. 1999); and the use, by the nest-founding gyne, of her shed forewing as a platform for the incipient garden (Fernandez-Marin et al. 2004).

Identification
Sosa-Calvo & Schultz (2010) - (Worker). Monomorphic. Posterior border of head in full-face view convex, interrupted by a median concavity and sometimes by blunt tubercles but never by teeth or spines. Eyes of variable size, strongly convex, hemispherical, or globose. Lacking ventral subocular prominence. Antennal scapes long usually surpassing occipital corners and bilobed at base at junction of antennal condyle. Clypeal apron (“anteclypeus” of Brandao and Mayhe-Nunes 2001) always present as smooth to weakly sculptured shining strip. Posterior lateral margins of clypeus, anterior to frontal lobes, produced into a pair of blunt to acuminate frontoclypeal teeth. Frontal lobes narrow, in some species incompletely covering antennal sockets, and always separated by fingerlike posterior projection of clypeus. Lateral corners of hypostoma with acute hypostomal teeth (hypostomal teeth rounded or absent in Apterostigma and Mycocepurus). Area of propleuron adjacent to inferior pronotal angle bearing a tooth, tubercle, carina, or otherwise sculptured and bearing erect hairs (sculpture and hairs absent in Mycocepurus and sculpture absent in Apterostigma). Promesonotum usually with spines or tubercles, rarely reduced to low ridges or carinae (as in Apterostigma), anteriorly with three pairs of spines or tubercles, but never with a crown of well-differentiated spines (as in Mycocepurus). Petiole with long peduncle and well-defined petiolar node lacking spines but sometimes with posterior carina (petiolar node weakly defined in Apterostigma and armed with two pairs of spines in Mycocepurus). Postpetiole, in dorsal view, usually trapezoidal with or without posterior margin emarginate, lateral margins usually confluent with anterior lateral margins of gaster. First gastral segment somewhat longer than wide; in dorsal view, its anterior and posterior margins straight, the lateral margins convex and anteriorly carinate. Sting present, protruding, and visible; frequently large. Body of most species covered with appressed to suberect squamate or spatulate hairs, in rare cases (described below) with erect or simple hairs (in Apterostigma hairs always long, simple, and flexuous [Lattke 1997, 1999], in Mycocepurus simple, short, and either erect, curved, or decumbent [Kempf 1963]).

Biology
Sosa-Calvo & Schultz (2010) - Colonies of most Myrmicocrypta species are small, consisting of < 200 individuals (Weber 1945, Murakami and Higashi 1997, Price et al. 2003). Nest form varies across species, usually consisting of either a single, spherical, shallow chamber in the soil or of a single, irregular chamber within rotting wood (Mann 1916, Weber 1941, 1945, 1947, 1968, 1969; Holldobler and Wilson 1990, Murakami and Higashi 1997; unpublished data). Workers are cryptic foragers in the leaf litter and thus rarely hand-collected in the field. Myrmicocrypta species reportedly use a wide variety of organic matter as substrates for their fungus gardens, including arthropod frass, wood pellets, insect corpses, seeds, flower parts, dry leaves, and other plant debris (Weber 1941, 1945, 1947, 1966, 1968, 1969; Holldobler and Wilson 1990, Murakami and Higashi 1997, Mueller et al. 2005). The only thorough study of Myrmicocrypta biology (Murakami and Higashi 1997) reports that Myrmicocrypta ednaella garden substrate consists mainly of wood chips and occasional insect corpses and that adult workers feed primarily upon plant nectar and sap, which they share with other workers via trophallaxis.

Nomenclature

 *  MYRMICOCRYPTA [Myrmicinae: Attini]
 * Myrmicocrypta Smith, F. 1860c: 73. Type-species: Myrmicocrypta squamosa, by monotypy.
 * Myrmicocrypta senior synonym of Glyptomyrmex: Emery, 1894c: 224.
 * GLYPTOMYRMEX [junior synonym of Myrmicocrypta]
 * Glyptomyrmex Forel, 1885a: 365. Type-species: Glyptomyrmex dilaceratum, by monotypy.
 * Glyptomyrmex junior synonym of Myrmicocrypta: Emery, 1894c: 224.

Sosa-Calvo & Schultz (2010) - The ant genus Myrmicocrypta (Formicidae: Myrmicinae: Attini) was established by Smith (1860) based on an alate gyne collected in Sao Paulo, Brazil. The genus has never been revised; genus-level taxonomic actions consist solely of a junior synonym (Glyptomyrmex, Emery 1894), the transfer of nine species to the attine genera Mycetophylax Emery, Kalathomyrmex Klingenberg & Brandao, Paramycetophylax Kusnezov, and Trachymyrmex Forel (Emery 1913, 1922; Santschi 1922, 1929; Weber 1958; Bolton 1995), and the transfer from the genus Apterostigma of the species Myrmicocrypta uncinatum (Emery 1894). Currently, the genus comprises 28 described species and subspecies (Bolton 1995, Bolton et al. 2007) distributed in the Neotropics from southern Mexico through Northern Argentina (Kempf 1972, Fernandez and Sendoya 2004). Except for Trinidad and Tobago, which are biotic extensions of the mainland, the genus is unknown in the Caribbean (Wheeler 1922a; Weber 1958, 1968; Wilson 1988; see Kempf 1972 for distributional information).

Smith (1860) created the genus Myrmicocrypta based on an alate gyne collected in Sao Paulo, Brazil. Mayr (1865) (p. 24) briefly defined the genus, citing the characters: wings of gynes with short hairs, with submarginal cell enclosed, lacking stigma and lacking discal cell; and very reduced frontal lobes in workers and gynes. Interestingly, in his description Smith (1860) (p. 74) points out a possible relationship between Myrmicocrypta and Oecodoma Latreille, the latter now regarded as a junior synonym of the attine leaf-cutting genus Atta F. (Roger (1863) p. 35). Because, contrary to other authors of the day, Smith’s (1858) concept of Oecodoma seemed to comprise our modern concept of the leaf-cutting attine genera Atta and Acromyrmex Mayr, his suggestion of a relationship between Oecodoma and Myrmicocrypta was unusually prescient.

The monophyly of Myrmicocrypta is well supported in molecular phylogenetic analyses of DNA sequences from four nuclear protein-coding genes for six species (Schultz and Brady 2008) and one nuclear proteincoding gene and one mitochondrial protein-coding gene for fourteen species (J. S.-C., unpublished data). Putative morphological synapomorphies for the genus include the following.

Worker

1. Antennal scapes bilobed at the base at the junction of the antennal condyle.

2. Posterior lateral margins of the clypeus, anterior to the frontal lobes, produced into a pair of blunt to acuminate frontoclypeal teeth.

3. Area of propleuron adjacent to the inferior pronotal angle bearing a tooth, tubercle, or carina.

4. Postpetiole with lateral margins usually confluent with the anterior lateral margins of the gaster.

5. Body of most species typically covered with appressed to suberect squamate or spatulate hairs, reversed to erect or simple hairs in M. camargoi, M. erectapilosa, and M. bucki.

Male

Propodeal spines extremely long and thin.