Strumigenys atropos

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

Nothing is known about the biology of Strumigenys atropos.

Identification

Bolton (2000) - A member of the Strumigenys rostrata-group. In the Malaysian material the hairs fringing the lateral clypeal margins are subequal in size to those on the anterior margin. The species most closely related to atropos is Strumigenys nepalensis, which is also known to occur in Thailand and West Malaysia. Workers of the two separate as follows.

S. atropos: Antenna with 6 segments. Anterior clypeal margin broadly shallowly concave across its entire width. Hairs fringing anterior clypeal margin larger than those fringing lateral margins. Hairs on clypeal dorsum small, almost suborbicular in dorsal view. Dorsum of head in profile without a pair of standing hairs just in front of highest point of vertex. Pronotal dorsum completely smooth and shining. Mesonotum with a single pair of standing hairs. Elongate standing hairs on petiole node recurved, fine and almost flagellate, contrasting with the hairs on the first gastral tergite.

S. nepalensis: Antenna with 4 segments. Anterior clypeal margin transverse. Hairs fringing anterior clypeal margin smaller than those fringing lateral margins. Hairs on clypeal dorsum narrowly spatulate in dorsal view. Dorsum of head in profile with a pair of standing hairs just in front of highest point of vertex. Pronotal dorsum weakly punctate-shagreenate. Mesonotum with three pairs of standing hairs. Elongate standing hairs on petiole node simple, weakly curved, similar to the hairs on the first gastral tergite.

Keys including this Species

• Key to Strumigenys of East Asia (as Pyramica)

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 5.816666667° to 5.816666667°.

North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

• Source: AntMaps

Distribution based on Regional Taxon Lists

Indo-Australian Region: Malaysia.
Oriental Region: Thailand (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.

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

Expand 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

Images from AntWeb

Worker. Specimen code casent0102598. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by MHNG, Geneva, Switzerland.

Nomenclature

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

• atropos. Pyramica atropos Bolton, 2000: 457 (w.) THAILAND. Combination in Strumigenys: Baroni Urbani & De Andrade, 2007: 116

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 1.6, HL 0.44, HW 0.34, CI 77, ML 0.06, MI 14, SL 0.20, SI 59, PW 0.20, AL 0.44. With mandibles fully closed there is a minute gap between their inner margins just in front of the anterior clypeal margin. Basal dental row of 7 teeth, consisting of alternating slightly taller, more acute teeth and slightly shorter, blunted teeth. Anterior clypeal margin broad and broadly shallowly concave across its entire width. Projecting spoon-shaped hairs that fringe the clypeal margins largest on the anterior margin; minute, closely appressed and inconspicuous laterally. Small appressed hairs on clypeal dorsum broadly scale-like, almost suborbicular. In full-face view dorsolateral margin of head with a continuous row of anteriorly curved spoon-shaped hairs. Similar hairs present all over cephalic dorsum behind clypeus, and dorsum also with a transverse row of 4 elongate slender remiform standing hairs just in front of the occipital margin. These hairs contrast strongly with the otherwise spoon-shaped curved pilosity. Eye very small, of only 1-2 ommatidia in total. Entire dorsum of head behind clypeus finely reticulate-punctate. Dorsal alitrunk glassy smooth everywhere. Pronotal humeral hair elongate and stout, straight to weakly curved. Mesonotum with a single pair of similar but shorter standing hairs. Ground-pilosity of promesonotum of scattered spatulate to narrowly spoon-shaped hairs that are curved toward the midline. Side of alitrunk smooth and shining everywhere. Anterodorsal angle of petiole node in profile with a single pair of long slender back-curved standing hairs that taper to fine apical points. Standing hairs on dorsa of postpetiole and first gastral tergite stouter than the petiolar pair, straighter and tending to be blunted apically. Hairs on dorsal (outer) surfaces of middle and hind tibiae narrowly spatulate, curved toward the apex and closely applied to the surface. Petiole, postpetiole and gaster smooth, the last with basigastral costulae present. Discs of petiole and postpetiole in dorsal view broader than long, the latter completely surrounded by spongiform tissue.

Paratypes. TL 1.6, HL 0.43-0.45, HW 0.33-0.34, CI 76-77, ML 0.06-0.08, MI 14-17, SL 0.20-0.21, SI 59-62, PW 0.20, AL 0.42-0.44 (3 measured).

Type Material

Holotype worker, Thailand: Kaeng Krachan N. P., 17.xi.1985, no. 24 (Lobl & Burckhardt) (Musee d'Histoire Naturelle Genève).

Paratypes. 1 worker with same data as holotype; 2 workers with same data hut 19.xi.1985, no. 26 (MHNG, 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 457, worker described)
• Khachonpisitsak, S., Yamane, S., Sriwichai, P., Jaitrong, W. 2020. An updated checklist of the ants of Thailand (Hymenoptera, Formicidae). ZooKeys 998, 1–182 (doi:10.3897/zookeys.998.54902).
• 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

• Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65