Sericomyrmex maravalhas

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Sericomyrmex maravalhas
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Sericomyrmex
Species: S. maravalhas
Binomial name
Sericomyrmex maravalhas
Ješovnik & Schultz, 2017

Sericomyrmex maravalhas F32c.jpg

Sericomyrmex maravalhas F32b.jpg

An inhabitant of the cerradão. Specimens have been noted as being found in typical cerradão, riparian forest and taken from rotten wood.

Identification

Jesovnik and Schultz (2017) - Small species; frontal lobe triangular; frontal carina robust, complete; eye convex, sometimes laterally protruding in full-face view; mandible dorsally glossy, smooth; gaster with four sharp carinae.

Sericomyrmex maravalhas can be separated from its sister species Sericomyrmex scrobifer by its smaller size; narrower, triangular frontal lobes (trapeziform in scrobifer); less robust frontal carinae; and eyes somewhat smaller and flatter. The closely related Sericomyrmex saramama is similar in size but differs from maravalhas by the absence of dorsal gastral carinae, less robust frontal lobes and frontal carinae, and smaller, flatter eyes. Sericomyrmex opacus, which is similar in size and has smooth mandibles, can be distinguished from maravalhas by the absence of dorsal gastral carinae; smaller, flat eyes, sometimes with a white layer; weaker, incomplete frontal carinae; and opacus-typical rectangular frontal lobes.

In addition to characters that are the same as in the worker, the most diagnostic character of the S. maravalhas queen is the presence of fully developed preocular carinae that almost join with the frontal carinae posteriorly, a relatively deep notch in the posterior margin of the scutellum, and large propodeal denticles. However, because our description is based on a single specimen, we do not know if these characters vary within the species.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: -8.9886° to -20.4261°.

 
North
Temperate
North
Subtropical
Tropical South
Subtropical
South
Temperate

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil (type locality).

Distribution based on AntMaps

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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.
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Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.
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Biology

Explore-icon.png 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.

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.

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.

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. ‎

Jesovnik and Schultz (2017) - An interesting feature of S. maravalhas is that, unlike adult workers of all other Sericomyrmex species that we examined under SEM, some of the maravalhas workers lack the thick, waxy, crystal-like cuticular layer. In S. maravalhas this layer can be entirely or partially absent so that the minutely papillate integument is visible, a condition otherwise known only in males and callow workers of other Sericomyrmex species. We know nothing about the chemical composition or function of this white, crystal-like layer, but the two most likely explanations are that it is either a cuticular secretion or microbial in origin. Considering the known complex microbial interactions in the attine ant symbiosis (Currie et al. 2003, 2006, Fernández-Marín et al. 2006, Little and Currie 2007), and considering that this layer covers the eyes of some Sericomyrmex species (see Sericomyrmex saussurei), this phenomenon needs to be further investigated.

Castes

Figure 33.
Figure 34.

Jesovnik and Schultz 2017. Figure 33. S. maravalhas worker (USNMENT00924090: (a, b, c, d, f, g) USNMENT01126226 (e, h, i), SEM images. a Head, full-face view b mandibles c eye d mesosoma and metasoma, dorsal view e mesosoma, lateral view f metasoma, dorsal view g head, papillate integument h mesosoma, integument with dense crystal-like layer i mesosoma, papillate integument with sparse crystal-like layer. Figure 34. S. maravalhas queen (USNMENT00924082). a Head b lateral profile c mesosoma, dorsal view; and gaster d lateral and e dorsal views.

Nomenclature

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

  • maravalhas. Sericomyrmex maravalhas Ješovnik & Schultz, 2017a: 56, figs. 32-35 (w.q.) BRAZIL (Mato Grosso).
    • Type-material: holotype worker, 9 paratype workers, 1 paratype queen.
    • Type-locality: holotype Brazil: Mato Grosso, Serra Azul State Park, Barra do Garças, -15.8571, -52.2617, 539 m., 5.vi.2011 (H. Vasconcelos); paratypes with same data.
    • Type-depositories: MZSP (holotype); BMNH, CASC, MCZC, MHNG, MZSP, UFUB, USNM (paratypes).
    • Distribution: Brazil.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

(holotype): HWe 0.80–0.98 (0.95) HW 0.78–1.00 (0.96) HW1 0.75–1.2 (0.98) HW2 0.82– 1.08 (1.03) HW3 0.54–0.75 (0.63) IFW1 0.51–0.68 (0.64) IFW2 0.19–0.30 (0.2) HL1 0.77–0.95 (0.88) HL2 0.68–0.83 (0.8) SL 0.58–0.73 (0.68) EL 0.13–0.2 (0.18) Om 8–11 (9) WL 1.03–1.28 (1.2) PL 0.21–0.32 (0.23) PPL 0.13–0.25 (0.21) GL 0.72–0.95 (0.85) HFL 0.82–1.08 (1) PW 0.52–0.71 (0.66) CI 97–110 (108) FLI 57–73 (67) SI 67–77 (72) OI 15–21 (19) CEI 7–17 (8) [N=30]

Pilosity. Pubescence dense, lighter than integument, appressed to decumbent. Hairs curved, darker in color at base, appressed to suberect, mostly decumbent.

Head. In full-face view slightly broader than long (CI=104 ± 3), posterior corner angular to acute, lateral margin of head slightly convex, posterior cephalic emargination distinct (CEI=10 ± 2), gradually impressed. Vertexal impression distinct, frontal tumuli faint. Mandibles with 7–8 teeth, dorsally smooth and shiny, finely transversely striate only along masticatory margin. Eye large (OI =18 ± 1), moderately convex, without white layer, 9–11 ommatidia across largest diameter. Frontal lobe relatively wide (FLI=68 ± 2), triangular, posterior margin shorter than medial, lateral margin in some specimens mildly concave. Frontal carina well developed, complete, reaching posterior cephalic corner. Antennal scape moderately long, sometimes almost reaching posterior cephalic corner (SI=72 ± 3).

Mesosoma. Mesosomal tubercles low and obtuse to moderately pronounced. Propodeal carinae low, sometimes serrate, sometimes with posterodorsal denticles.

Metasoma. Petiole and postpetiole each with two low, short, serrate carinae dorsally, on petiole sometimes reduced to denticles, best seen in dorsolateral view. Postpetiole usually with another pair of low carinae laterally. First gastral tergite with lateral and dorsal carinae strongly developed.

Queen

HWe 1.12 HW 1.12 HW1 1.24 HW2 1.36 HW3 0.84 IFW1 0.84 IFW2 0.4 HL1 1.12 HL2 0.99 SL 0.75 EL 0.24 Om 20 EW 0.08 WL 1.72 PL 0.33 PPL 0.3 GL 1.6 HFL 1.25 PW 1 CI 100 FLI 75 SI 67 OI 22 [N=1]

Head. Mandible with 8 teeth, dorsally glossy and smooth, finely transversely striate only along masticatory margin. Preocular carina extending posterior to eye, becoming thinner posteriorly, almost converging with frontal carina to form complete scrobe, best seen in lateral view. Eye large, convex, protruding from sides of head in full-face view, 20 ommatidia across largest diameter. Frontal lobe as in worker, antennal scape not reaching posterior cephalic corner (SI=67).

Mesosoma. Lateral pronotal tubercles low and obtuse. Scutum in dorsal view with notauli and median mesoscutal line faint. Parapsidal lines thin, slightly curved. Groove separating axillae in dorsal view weakly transversely costate. Scutellum inflated, short in dorsal view, narrowing posteriorly, with relatively deep V-shaped posterior notch. Propodeum with two obtuse, laterally flattened, diverging denticles.

Metasoma. First gastral tergite with lateral carinae strongly developed, dorsal carinae faint, anteromedian groove distinct.

Type Material

Holotype worker: BRAZIL, Mato Grosso, Serra Azul State Park, Barra do Garças, -15.8571, -52.2617, 539m, 5 Jun 2011, H. Vasconcelos (Museu de Zoologia da Universidade de Sao Paulo: 1w, USNMENT00924081). Paratypes: same data as holotype (MZSP: 1w, USNMENT00924090) (National Museum of Natural History: 1q, USNMENT00924082; 1w, USNMENT00924087; 1w, USNMENT00924089), (MBC-UFU: 1w, USNMENT00924083), (Museum of Comparative Zoology: 1w, USNMENT00924092), (California Academy of Sciences: 1w, USNMENT00924086; 1w, USNMENT00924091), (The Natural History Museum: 1w, USNMENT00924088), (Musee d'Histoire Naturelle Genève: 1w, USNMENT00924095).

Etymology

This species is named after our myrmecologist colleague Jonas Maravalhas, who sorted and sent to us the specimens of this species used in our molecular phylogenetic analyses. The molecular data were crucial, in combination with morphological evidence, for recognizing maravalhas as a distinct species. Even better, Jonas’ surname has the same root as “maravilhas” which means “wonders” in Portuguese, an appropriate adjective for this new species. The species name is a noun in apposition.

References

  • Ješovnik, A. and Schultz, T.R. 2017. Revision of the fungus-farming ant genus Sericomyrmex Mayr (Hymenoptera, Formicidae, Myrmicinae). ZooKeys. 670:1–109. doi:10.3897/zookeys.670.11839