Strumigenys myllorhapha

AntWiki: The Ants --- Online
Strumigenys myllorhapha
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. myllorhapha
Binomial name
Strumigenys myllorhapha
(Brown, 1959)

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Specimen Labels

A common inhabitant of moist tropical forest habitats across a wide range of elevation, from lowland rainforest through to cloud forest. It is a denizen of the litter as evidenced by the many hundreds of samples obtained from forest litter sampling but may also opportunistically nest in the canopy under epiphytes. Nests are presently known from in or under dead wood on ground. (Longino, Ants of Costa Rica)

Identification

Bolton (2000) - A member of the crassicornis-complex in the Strumigenys gundlachi group. The very long mandibles of myllorhapha (MI 61 - 67) are not matched by any other species of the crassicornis-complex, but several species of the gundlachi-complex have the MI approaching or exceeding 60. None of these have the dentition or the extremely elongated labral lobes of Strumigenys myllorhapha.

Longino (Ants of Costa Rica) - Mandibles in full-face view linear, elongate and narrow; at full closure engaging only at apex; ventral surface of petiole without spongiform tissue; leading edge of scape with freely projecting hairs; inner margin of mandible with a clearly defined submedian tooth near the midlength; labral lobes long, trigger hairs at apices of lobes short; middle preapical denticle distinctly larger than flanking denticles, similar in size to submedian tooth; mandibles relatively long (MI 61-67); mesosomal dorsum evenly convex, propodeal suture not impressed; total head length greater than 0.90mm. Also see Bolton (2000:190).

Specimens from the lowlands are light ferruginous and relatively smaller, while those from montane regions are dark brown and relatively larger (see Costa Rican Ants and Elevation). In the case of myllorhapha I have been able to detect neither morphological discontinuity between light and dark forms, nor zones of sympatry. Therefore I treat the light and dark forms as intraspecific variation in this case.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 16.974° to 9.167°.

 
North
Temperate
North
Subtropical
Tropical South
Subtropical
South
Temperate

Distribution based on Regional Taxon Lists

Neotropical Region: Belize, Costa Rica (type locality), Honduras, Mexico, Panama.

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 Overview of Strumigenys biology 
Strumigenys were once thought to be rare. The development and increased use of litter sampling methods has led to the discovery of a tremendous diversity of species. Many species are specialized predators (e.g. see Strumigenys membranifera and Strumigenys louisianae). Collembola (springtails) and other tiny soil arthropods are typically favored prey. Species with long linear mandibles employ trap-jaws to sieze their stalked prey (see Dacetine trap-jaws). Larvae feed directly on insect prey brought to them by workers. Trophallaxis is rarely practiced. Most species live in the soil, leaf litter, decaying wood or opportunistically move into inhabitable cavities on or under the soil. Colonies are small, typically less than 100 individuals but in some species many hundreds. Moist warm habitats and micro-habitats are preferred. A few better known tramp and otherwise widely ranging species tolerate drier conditions. Foraging is often in the leaf litter and humus. Workers of many species rarely venture above ground or into exposed, open areas. Individuals are typically small, slow moving and cryptic in coloration. When disturbed individuals freeze and remain motionless. Males are not known for a large majority of species.

Castes

Nomenclature

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

  • myllorhapha. Neostruma myllorhapha Brown, 1959b: 12, fig. 4 (w.) COSTA RICA. Combination in Pyramica: Bolton, 1999: 1672; in Strumigenys: Baroni Urbani & De Andrade, 2007: 124. See also: Bolton, 2000: 190.

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

Description

Worker

Bolton (2000) - TL 2.3-2.8, HL 0.58-0.67, HW 0.40-0.49, CI 72-75, ML 0.37-0.44, MI 61-67, SL 0.23-0.28, SI 55-59, PW 0.28-0.34, AL 0.60-0.74 (20 measured). Characters of crassicornis complex but with mandibles and labral lobes very long. Enlarged submedian tooth shifted distally so that it is between one-half and two-thirds the mandible length from the base. Between it and the apicodorsal tooth with 4 - 6 denticles of varying size, proximal to it with 5 - 8 denticles; generally there are more denticles proximal of the sub median tooth than distal to it. Apex of mandible with 3 minute intercalary denticles between apicodorsal and apicoventral teeth. Vertical inner face of mandible below masticatory margin with an elongate pale apparently glandular area close to the base. In shape it is an elongate tear-drop, pointed anteriorly and twice longer than broad; its margins are sharply defined and it is much paler in colour than the surrounding cuticle. The structure is visible even when the mandibles are fully closed. The basal mandibular gland described above is also discernible in Strumigenys auctidens, Strumigenys pasisops and Strumigenys stenotes but in all of these it is shorter, broader and by no means as sharply defined nor obviously paler than the surrounding cuticle. Colour is variable in myllorhapha, ranging from brownish yellow to almost black. Individual colour appears to be altitude linked, with darker specimens from higher altitudes.

Type Material

Bolton (2000) - Holotype worker, COSTA RICA: no locality data (F. Nevermann) (Museu de Zoologia da Universidade de Sao Paulo) (examined).

References

References based on Global Ant Biodiversity Informatics

  • Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
  • Branstetter M. G. and L. Sáenz. 2012. Las hormigas (Hymenoptera: Formicidae) de Guatemala. Pp. 221-268 in: Cano E. B. and J. C. Schuster. (eds.) 2012. Biodiversidad de Guatemala. Volumen 2. Guatemala: Universidad del Valle de Guatemala, iv + 328 pp
  • Brown W. L. Jr. 1959. A revision of the dacetine ant genus Neostruma. Breviora 107: 1-13.
  • Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
  • Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
  • INBio Collection (via Gbif)
  • Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
  • Longino J. T., and N. M. Nadkarni. 1990. A comparison of ground and canopy leaf litter ants (Hymenoptera: Formicidae) in a Neotropical montane forest. Psyche (Cambridge) 97: 81-94.
  • Longino J. T., and R. K. Colwell. 2011. Density compensation, species composition, and richness of ants on a neotropical elevational gradient. Ecosphere 2(3): 16pp.
  • Longino J. et al. ADMAC project. Accessed on March 24th 2017 at https://sites.google.com/site/admacsite/
  • Longino, J.T. and N. M. Nadkarni. 1990. A comparison of ground and canopy leaf litter ants (Hymenoptera: Formicidae) in a Neotopical Montane Forest. Psyche 97:81-93.
  • Smith M. A., W. Hallwachs, D. H. Janzen. 2014. Diversity and phylogenetic community structure of ants along a Costa Rican elevational gradient. Ecography 37(8): 720-731.
  • Sosa-Calvo J., S. O. Shattuck, and T. R. Schultz. 2006. Dacetine ants of Panama: new records and description of a new species. Proceedings of the Entomological Society of Washington 108: 814-821.