Mycetomoellerius mikromelanos

Mycetomoellerius mikromelanos
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Mycetomoellerius
Species:	M. mikromelanos
Binomial name
	Mycetomoellerius mikromelanos; Cardenas, Schultz, & Adams, 2021

Mycetomoellerius mikromelanos is the most common ‘funnel Mycetomoellerius’ found on Pipeline Road, near Gamboa, Panama. Gynes establish nests from the start of the rainy season (May) into July. They nest in vertical clay embankments with entrances shaped like funnels (i.e., auricles) with flared margins (Mueller & Wcislo, 1998; Pérez-Ortega et al., 2010). Colonies are often tucked under roots or overhangs and occur in high densities (as close as ∼5cm apart) along creeks or are isolated in the forest at the base of trees. Colonies of M. mikromelanos have up to five vertically arranged chambers with single vertical tunnels between them. We removed the auricles from 16 nests and 15 were rebuilt to roughly the same size within seven days, suggesting the funnel structure appear to be biologically important (Figs. S7 & S8; also see Mueller & Wcislo, 1998; Schultz et al., 2002; Pérez-Ortega et al., 2010; Helms, Peeters & Fisher, 2014). Several functional hypotheses have been proposed from physical barriers for army-ant raids to visual nest recognition cues. But nest entrances could also be involved in gas exchange currents that disperse colony odors or assist with colony respiration (see Longino, 2005; Helms, Peeters & Fisher, 2014). Further research is necessary to clarify their biological function.

Identification

Measurements for all castes are in Table 2 and Table S4. We found characters that reliably separate M. mikromelanos from Mycetomoellerius zeteki. However, due to the variability of worker castes (e.g., mesosoma spines), intermediate character states occur in some individuals. The following characters are those most useful for diagnosis.

Workers (1) cuticle coloration dark-ferrugineous (Figs. 2A–2C); (2) overall integument bearing granulose irrorate sculpturing (Figs. 2A–2C); (3) frontal lobe with crenate margins and weak antero-lateral spine (Fig. 2B); (4) hooked spatulate bi-colored setae medial to frontal carina on disc of head capsule (Fig. 2B); (5) scape surpassing occipital corners when lodged in antennal scrobe (Fig. 2B); (6) convex margin of the compound eye extending past the lateral border of the head by more than half of its visible diameter in full-face view (Fig. 2B).

Gynes (1) cuticle coloration dark-ferrugineous (Figs. 2D–2F); (2) supraocular spine superior to compound eye by more than or equal to the eye length (Fig. 2D); (3) small arcuate ridge superior to and reaching anterior ocellus, with its terminal ends directed postero-laterally (Fig. 2D); (4) lateral ocelli partially obscured in full-face view (Fig. 2D); (5) mesoscutum with random-reticulate sculpturing (Fig. 2F & S5a); (6) wings bicolored, venation ferrugineous-brown (Figs. 2E, 2F] & S5b); (7) hindwing with 7–9 hamuli (Fig. 2E & S5b).

Males (1) bicolored; head and mesosoma ferrugineous-brown; metasoma dark testaceousorange (Fig. 3A); (2) complete carinate-rugulose sculpturing of posterior head capsule, arranged nearly perpendicular to the longitudinal axis of the head (Fig. 3A); inferior to frontal lobe, sculpturing sparsely carinate and finely reticulate (Fig. 3A & S6); (3) mandible distinctly smaller compared to M. zeteki; (4) corners of medial clypeal emargination rounded (Fig. 3B & S6) ocelli smaller relative to M. zeteki in full-face view, occipital corner of head capsule visible (Fig. 3B); (6) propodeal spines wider at base than long (Fig. 3A).

Santos et al. (2025) provide a multi-entry interactive key based on the xper3 platform which contains 27 characters and, as terminals, 30 species of Mycetomoellerius, representing almost all described species except for Mycetomoellerius echinus, Mycetomoellerius gaigei and Mycetomoellerius guianensis, which are excluded due to lack of clear information or available specimens for study.

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Panama (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Biology

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Explore Fungus Growing

For additional details see Fungus growing ants.

A handful of ant species (approx. 275 out of the known 15,000 species) have developed the ability to cultivate fungus within their nests. In most species the fungus is used as the sole food source for the larvae and is an important resource for the adults as well. Additionally, in a limited number of cases, the fungus is used to construct part of the nest structure but is not as a food source.

These fungus-feeding species are limited to North and South America, extending from the pine barrens of New Jersey, United States, in the north (Trachymyrmex septentrionalis) to the cold deserts in Argentina in the south (several species of Acromyrmex). Species that use fungi in nest construction are known from Europe and Africa (a few species in the genera Crematogaster, Lasius).

The details of fungal cultivation are rich and complex. First, a wide variety of materials are used as substrate for fungus cultivating. The so-called lower genera include species that prefer dead vegetation, seeds, flowers, fruits, insect corpses, and feces, which are collected in the vicinity of their nests. The higher genera include non leaf-cutting species that collect mostly fallen leaflets, fruit, and flowers, as well as the leafcutters that collect fresh leaves from shrubs and trees. Second, while the majority of fungi that are farmed by fungus-feeding ants belong to the family Lepiotaceae, mostly the genera Leucoagaricus and Leucocoprinus, other fungi are also involved. Some species utilise fungi in the family Tricholomataceae while a few others cultivate yeast. The fungi used by the higher genera no longer produce spores. Their fungi produce nutritious and swollen hyphal tips (gongylidia) that grow in bundles called staphylae, to specifically feed the ants. Finally, colony size varies tremendously among these ants. Lower taxa mostly live in inconspicuous nests with 100–1000 individuals and relatively small fungus gardens. Higher taxa, in contrast, live in colonies made of 5–10 million ants that live and work within hundreds of interconnected fungus-bearing chambers in huge subterranean nests. Some colonies are so large, they can be seen from satellite photos, measuring up to 600 m3.

Based on these habits, and taking phylogenetic information into consideration, these ants can be divided into six biologically distinct agricultural systems (with a list of genera involved in each category):

Nest Construction

A limited number of species that use fungi in the construction of their nests.

some Crematogaster
some Lasius

Lower Agriculture

Practiced by species in the majority of fungus-feeding genera, including those thought to retain more primitive features, which cultivate a wide range of fungal species in the tribe Leucocoprineae.

Coral Fungus Agriculture

Practiced by species in the Apterostigma pilosum species-group, which cultivate fungi within the Pterulaceae.

some Apterostigma

Yeast Agriculture

Practiced by species within the Cyphomyrmex rimosus species-group, which cultivate a distinct clade of leucocoprineaceous fungi derived from the lower attine fungi.

some Cyphomyrmex

Generalized Higher Agriculture

Practiced by species in several genera of non-leaf-cutting "higher attine" ants, which cultivate a distinct clade of leucocoprineaceous fungi separately derived from the lower attine fungi.

Leaf-Cutter Agriculture

A subdivision of higher attine agriculture practiced by species within several ecologically dominant genera, which cultivate a single highly derived species of higher attine fungus.

Note that the farming habits of Mycetagroicus (4 species) are unknown. Also, while species of Pseudoatta (2 species) are closely related to the fungus-feeding genus Acromyrmex, they are social parasites, living in the nests of their hosts and are not actively involved in fungus growing. ‎

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

mikromelanos. Mycetomoellerius mikromelanos Cardenas, Schultz, & Adams, in Cardenas et al., 2021: 13, figs. 1-3 (w.q.m.) PANAMA.

Type Material

HOLOTYPE: Worker, Republic of Panama. [9.16328, -79.74413, Panama: Colón Province, Pipeline Rd, 16E, 62m, 13.v.2017, Cody Raul Cardenas, CRC170513-04] [USNMENT01123723]. Repository: USNM.
PARATYPES: 15 Workers, Republic of Panama. Same label data as holotype. Repositories: USNM (3): USNMENT01123726, USNMENT01123727, USNMENT01123728; MZSP (4): OSUC 640618, OSUC 640619, OSUC 640620, OSUC 640621; STRI (5): OSUC 640635, OSUC 640636, OSUC 640637, OSUC 640638, OSUC 640639; OSUC (3): OSUC 640606, OSUC 640607, OSUC 640608.
PARATYPES: 11 Gynes, Republic of Panama. Same label data as holotype. Repositories: USNM (4): USNMENT01123724, USNMENT01123729, USNMENT01123730, USNMENT01123731; MZSP (3): OSUC 640622, OSUC 640623, OSUC 640624; STRI(3): OSUC 640640, OSUC 640641, OSUC 640642; OSUC (1): OSUC 640609. PARATYPES: 7 Males, Republic of Panama. Same label data as holotype. Repositories: USNM (4): USNMENT01123725, USNMENT01123732, USNMENT01129733, USNMENT01129734; MZSP (1): OSUC 640625; STRI (1): OSUC 640643; OSUC (1): OSUC 640610.

Description

References