Mycetophylax simplex

In 2005, Albuquerque et al. published information on nest density of M. simplex at Rio Grande do Sul, Brazil coastal beaches. Diehl & Diehl-Fleig (2007) described M. simplex nest architecture and colony populations.

Identification
Mycetophylax simplex can be easily distinguished from other Mycetophylax by its yellow-brownish color and the unarmed propodeum.

Distribution
Until now the known geographic distribution of M. simplex included only the State of Rio Grande do Sul, Brazil, but we collected colonies of this species at the Isle of Florianópolis, Santa Catarina State, Brazil for the first time. Fowler (1980) recorded M. simplex in Paraguay, but as this species is currently known only along the Atlantic beaches, therefore this previous collection information should be used with care; we have not examined this material. (Klingenberg and Brandao 2009)

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Paraguay, Uruguay.

Nomenclature

 *  simplex. Cyphomyrmex simplex Emery, 1888c: 361 (w.). BRAZIL.
 * Klingenberg & Brandão, 2009: 20 (q.m.).
 * Combination in C. (Mycetophylax): Emery, 1913b: 251.
 * Combination in Mycetophylax: Kempf, 1972a: 146; Sosa-Calvo et al., 2017: 9.

Type Material
Klingenberg and Brandao 2009:

Cyphomyrmex simplex (worker) Syntype Brazil, Rio Grande do Sul, São Lourenço (type specimens not localized)

Description
Klingenberg & Brandão, 2009:

Worker
Range of measurements (in mm) and indices of examined specimens (N = 36): IOD 0.83-1.03; HL 0.85-1.01; CI 96-106; SL 0.49-0.82; SI 58-82; ML 0.34-0.48; MI 39-52; WL 1.05-1.30; PrW 0.52-0.69; PL 0.19-0.26; PPL 0.22-0.27; GL 0.70-0.92; FL 0.92-1.14; TL 3.30-4.05.

Color yellow to brownish, opaque, clypeus castaneous; masticatory border, median portion of clypeus, labrum, frontal area and coronal suture dark brown. Area between preocular and frontal carinae hairless. Surface of frons with small irregular pores; a single seta coming out from each of them (only visible with higher magnifications). Whole body, legs and antennae with short, sparse and appressed white hairs, brighter than integument, but the area between preocular carinae and frontal carinae, lateral faces of the mesosoma, dorsal discs of the coxae and petiole with even sparser pilosity. Masticatory border of mandibles with longer hairs. Sculpture reticulate. Mandibular dorsal disc with very fine longitudinal rugae. Integument of the frontal lobes with a rounded semitransparent spot on each side, above the antennal insertions, darker than the rest of the integument of the frontal lobes.

Head as long as wide (see CI), almost heart-shaped. Margin of vertexal in full face view concave, poserolateral corners rounded. Compound eyes with eleven ommatidia at maximum length and nine ommatidia at maximum width. Masticatory border of mandibles with seven to eight triangular teeth, the three most apical the same in size, the others somewhat smaller. Anterior margin of clypeus almost straight. Frontal lobes slender, covering the antennal insertions, but their maximum expansions attaining less than half the distance between the median line and external border of the head. External margin of frontal lobes gently rounded. Frontal and lateral carinae continuing posteriorly up to half the distance between the posterior margin of the eyes and vertexal margin. Antennal scapes slightly curved apically, only reaching the posterolateral corners of the head. Antennae ending in a two segmented club, the last antennal segment as long as the two before combined.

Pronotum convex with vestigial tumuli and pointed inferior pronotal spines. In lateral view mesonotum separated from pronotum by a distinct rounded suture, mesonotum projecting over the pronotum. Metapropodeal impression shallow. Basal face of propodeum slightly convex, a little longer than the straight declivous face meeting in an angle, but lacking spines or protuberances. Inferior margin of pronotum, katepisternum and metapleura bordered by a broad translucent carina. Propodeal spiracle small, with rounded opening 45° oblique in relation to the main body axis. Node of petiole as wide as high, in dorsal view, twice as wide as peduncle; ventral process as an acute denticle. Postpetiole wider than high.

Queen
Range of measurements (in mm) and indices of examined specimens (N = 10): IOD 1.14-1.20; HL 1.00-1.12; CI 104-116; SL 0.82-0.9; SI 71-78; ML 0.48-0.56; MI 44-52; WL 1.64-1.68; PL 0.30-0.36; PPL 0.24-0.32; GL 1.32-1.40; TL 5.10-5.30.

Color yellow to brownish, depending on age, masticatory border of mandibles, middle portion of clypeus, frontal area, area in front and lateral to the ocelli, and parapsidial areas brownish. Most characters as in the conspecific workers. Compound eyes with 18 ommatidia at maximum length and 14 ommatidia at maximum width. Pronotum with blunt anterior inferior spines. In lateral view, flattened scutum covering almost two thirds of pronotum. Notaulices indistinct. Parapsidial lines shallowly impressed. Scutellum subquadrate, anterior margin slightly concave, wider anteriorly; posterior margin concave with vestigial spines. Anepisternum subtriangular and katepisternum subquadrate, separated from the metapleura by a distinct suture.

Male
Range of measurements (in mm) and indices of examined specimens (N = 9): IOD 0.56-0.68; HL 0.56-0.68; CI 97-103; SL 0.58-0.76; SI 100-112; ML 0.24-0.30; MI 40-45; WL 1.30-1.70; PL 0.20-0.30; PPL 0.18-0.24; GL 0.94-1.34; TL 3.50-4.56.

Color dark brown, mandibles, antennae and legs yellowish. Integument reticulate with golden appressed shiny hairs. Hairs at external margin of mandible twice the length of the others. Mandibles with six to seven triangular teeth, decreasing in size from apical to basal, sometimes with varying distances between them. Clypeus anterior margin straight, with a distinct median impression on the anteclypeus. Median seta visible, with size similar to the mandible hairs. Median portion of clypeus bulging up to the level of half of the antennal insertions. Frontal carinae visible until the level of the posterior margin of compound eyes. Lateral carinae following the compound eyes, straight and directed backwards at posterior third. Compound eyes with 18 ommatidia at maximum length and 14 ommatidia at maximum width. Antennae 13-segmented. Antennal scapes straight, surpassing posterolateral corners of the head by half of their length. Antennal apical segment as long as the two preceding segments.

In dorsal view, anterior margin of scutum rounded, posterior margin convex. Parapsidial lines distinctly impressed, shiny, glabrous. Lateral margins of scutum as strong carinae. Prescutellum relatively wide, axillae subtriangular. Scutum-scutellar sulcus with transverse rugae. In lateral view anepisternum subtriangular and katepisternum subquadrate. Median coxa occupying only the posterior fourth of katepisternum inferior margin. Propodeal spiracle parallel in relation to the main body axis.

Petiolar peduncle reduced and node strongly developed, rounded. Ventral process poorly developed. Anterior margin of node meeting the peduncle in a square angle, dorso-posterior portion concave, in side view. In dorsal view, petiole subrectangular and slightly wider anteriorly. Postpetiole in dorsal view subquadrate, wider than petiole, wider posteriorly. Spiracle of first gastral tergite visible.

References based on Global Ant Biodiversity Informatics

 * Solomon S. E., C. Rabeling, J. Sosa-Calvo, C. Lopes, A. Rodrigues, H. L. Vasconcelos, M. Bacci, U. G. Mueller, and T. R. Schultz. 2019. The molecular phylogenetics of Trachymyrmex Forel ants and their fungal cultivars provide insights into the origin and coevolutionary history of ‘higher-attine’ ant agriculture. Systematic Entomology 44: 939–956.