Strumigenys dyschima

Strumigenys dyschima
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Strumigenys
Species:	S. dyschima
Binomial name
	Strumigenys dyschima; (Bolton, 2000) Specimen Labels

The few known specimens are from a soil core in mixed dipterocarp forest (type) and limestone-rainforest litter sampling.

Identification

Bolton (2000) - A member of the Strumigenys murphyi-group. Closely related to the Malaysian species Strumigenys murphyi, the two are distinguished as follows.

S. dyschima: Minute species, HW 0.37. Apicodorsal tooth of mandible not overlapping outer margin of opposite mandible at full closure. Flattened hairs that project from inner margin of mandible shorter than longest preapical tooth. Small orbicular hairs on head restricted to area immediately behind clypeus. Pronotal dorsum longitudinally costulate.

S. murphyi: Larger species, HW 0.45 or more. Apicodorsal tooth of mandible strongly overlapping outer margin of opposite mandible at full closure. Flattened hairs that project from inner margin of mandible longer than longest preapical tooth. Small orbicular hairs on head present from posterior margin of clypeus to transverse crest on vertex. Pronotal dorsum reticulate-punctate.

Keys including this Species

Key to Strumigenys of East Asia (as Pyramica)

Distribution

The previous record from Yunnan (Liu et al. 2015) is now re-identified as Strumigenys formosa instead. See S. formosa for a detailed discussion. With the correction, the native range of S. dyschima is once again limited to the Sundaic region (Borneo) (Tang & Guenard, 2023).

Latitudinal Distribution Pattern

Latitudinal Range: 21.91133333° to 4.95°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: AntMaps

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo (type locality), Indonesia, Malaysia.
Palaearctic Region: China.

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.

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.

Biology

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.

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Castes

Nomenclature

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

dyschima. Pyramica dyschima Bolton, 2000: 451, fig. 264 (w.) BORNEO. Combination in Strumigenys: Baroni Urbani & De Andrade, 2007: 119

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

Description

Worker

Holotype. TL 1.5, HL 0.34, HW 0.37, CI 109, ML 0.14, MI 41, SL 0.22, SI 59, PW 0.24, AL 0.40. Inner margin of mandible with a series of medially directed small flattened hairs and with 2-3 small preapical teeth; basal most preapical tooth the largest, triangular and located at about the midlength of the mandible. Apicodorsal tooth the longest and overlapping its counterpart from the opposing mandible, but not massively enlarged nor spiniform, not extending beyond the outer margin of the opposing mandible at full closure. Anterior clypeal margin with a few flattened projecting hairs, the clypeal dorsum only with minute inconspicuous ground-pilosity. Cephalic dorsum immediately behind clypeus with two arched transverse rows of small orbicular hairs, with 6 hairs in each row. There may be 2-3 minute flattened hairs immediately posterior to the second row, but orbicular hairs similar to those in the two rows are absent from head behind this level. Transverse crest of vertex conspicuous, approximately straight across most of vertex but on each side weakening and angled forward toward the anterolateral angle of the occipital lobe. S ides of occipital lobes in full-face view more or less straight, distinctly convergent posteriorly. Leading edge of scape with 6-7 small spoon-shaped hairs that are curved toward the base of the scape and decrease in size toward the scape apex. Apex of the subbasal lobe of the scape with a larger flattened anteriorly directed hair; inner margin of lobe with 2 flattened hairs that curve toward the apex of the scape. Head and alitrunk otherwise with minute inconspicuous ground-pilosity but without standing hairs of any form. Eye minute, of a single ommatidium. Head finely and densely reticulate-punctate. Pronotal dorsum with posteriorly divergent fine longitudinal costulae. Mesonotum in profile saddle-shaped, its dorsal outline concave medially. Sides of alitrunk more or less smooth. Petiole and postpetiole without standing hairs but first gastral tergite with short erect straight pilosity that is clavate apically. Petiole node broader than long in dorsal view, finely shagreenate and dull. Basigastral costulae short but strongly developed.

Type Material

Holotype worker, Malaysia: Sarawak, 4th Division, Gn. Mulu N. P., ii.1978, soil core, mixed dipterocarp forest (N. M. Collins) (The Natural History Museum).

References

Baroni Urbani, C. & De Andrade, M.L. 2007. The ant tribe Dacetini: limits and constituent genera, with descriptions of new species. Annali del Museo Civico di Storia Naturale “G. Doria” 99:1-191.
Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 451, fig. 264 worker described)
Tang, K. L., Guénard, B. 2023. Further additions to the knowledge of Strumigenys (Formicidae: Myrmicinae) within South East Asia, with the descriptions of 20 new species. European Journal of Taxonomy 907, 1–144 (doi:10.5852/ejt.2023.907.2327).

References based on Global Ant Biodiversity Informatics

Liu C, B. Guénard, F Hita Garcia, S. Yamane, B. Blanchard, and E. Economo. New records of ant species from Yunnan, China. Submitted to Zookeys
Pfeiffer M., and D. Mezger. 2012. Biodiversity Assessment in Incomplete Inventories: Leaf Litter Ant Communities in Several Types of Bornean Rain Forest. PLoS ONE 7(7): e40729. doi:10.1371/journal.pone.0040786
Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58