Strumigenys elegantula

Strumigenys elegantula
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Strumigenys
Species group:	leptothrix
Species:	S. elegantula
Binomial name
	Strumigenys elegantula; (Terayama & Kubota, 1989) Specimen labels

This species is widespread within continental Asia and has been recorded in Hong Kong, Macao, Guangdong, Guangxi (China) as well as in Thailand (Brassard et al., 2020). It was originally found in the leaf litter of an dry evergreen forest. In Hong Kong, this seldom encountered ant was found across a wide range of areas and habitats including managed grasslands, trees along roadsides, shrubland, secondary forest, and Feng Shui woods. Known elevation range in Hong Kong is from 1 to 254 m (Tang et al., 2019; Tang & Guenard, 2023).

Photo Gallery

Tang & Guenard (2023), Fig. 16. Workers of Strumigenys elegantula in full-face, profile and dorsal views. A–C. Worker from Hong Kong (ANTWEB1009804). D–F. Worker from Thailand (ANTWEB1011998).
Fig. 2. Mandible close-ups of workers from the elegantula-complex in the Strumigenys leptothrix-group. A–B. S. intermedia (TT01353). C. S. elegantula from Hong Kong (RHL00290). D. S. jacobsoni from Vietnam (ANTWEB1011973).

Identification

Tang & Guenard (2023) - A member of the elegantula complex in the Strumigenys leptothrix-group. Strumigenys elegantula can be distinguished from other species in the S. leptothrix-group by a combination of the following characters:

cephalic dorsum with appressed plank-like to subspatulate setae
laterally projecting seta present in full-face view
in profile view, erect seta on cephalic dorsum restricted to area between highest point of the vertex and occipital margin
pronotum marginated dorsolaterally
propodeal spines subtended by broad lamellae; femora, tibiae and basitarsi with long erect setae

After the description of Strumigenys intermedia and Strumigenys doydeei, some of the specimens that were once recognized as S. elegantula are now re-identified accordingly. As such, we have revised the description of S. elegantula, based on photos of the type specimen from Taiwan, as well as the specimens from Hong Kong and Thailand. See Strumigenys intermedia for a detailed comparison between the species.

Specimens from Macau and the majority of those from Hong Kong are now re-identified as Strumigenys intermedia, while CASENT0285186 from Chaiyaphum Province of Thailand (inspected by Bolton (2000) and currently recorded on AntWeb) (Fig. 15A–C) should be S. cf. doydeei instead. Specimens from Guangdong and Guangxi provinces of mainland China should be revisited to verify their identification. However, with the confirmation of its presence in Hong Kong (Fig. 16A–C) and Thailand (Fig. 16D–F), the geographic range of the species is unlikely to be drastically changed after the revision. Its presence in Fujian Province of mainland China, as well as Laos and Vietnam is likely.

After a careful examination of our specimens with opened mandibles, we have determined that S. elegantula has a different dentition pattern in comparison with S. leptothrix (Fig. 2C) and should be placed in a separate species complex. Specimens from Taiwan should be checked if they have the same dental morphology. See the species group section for detailed discussion.

Bolton (2000) - Seven species of this group, of which elegantula is one, have the propodeal spines subtended by lamellae (see discussion under Strumigenys leptothrix). Of the seven leptothrix and Strumigenys jacobsoni are quickly distinguished from the other five (Strumigenys alecto, Strumigenys benten, elegantula, Strumigenys formosimonticola, Strumigenys japonica) as the former pair have the cephalic dorsum very densely hairy, with standing hairs arising all over the dorsum from the posterior clypeal margin to the occipital margin. In the other five species standing hairs on the dorsum of the head are much sparser and more limited in distribution, restricted to the zone around the highest point of the vertex to the occipital margin, or absent. Of this complex only alecto and elegantula have long freely projecting hairs on the tibiae; elegantula has the pronotum marginate dorsolaterally and the mesopleuron reticulate-punctate, whereas in alecto the pronotal dorsum rounds into the sides and the mesopleuron is completely smooth.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 22.5382° to 22.230898°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: AntMaps

Distribution based on Regional Taxon Lists

Oriental Region: Taiwan (type locality), Thailand.
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

Worker

Images from AntWeb


Worker. Specimen code casent0102542. Photographer April Nobile, uploaded by California Academy of Sciences.	Owned by MHNG, Geneva, Switzerland.


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Nomenclature

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

elegantula. Smithistruma elegantula Terayama & Kubota, 1989: 788, figs. 23-27 (w.q.) TAIWAN. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 119. See also: Bolton, 2000: 431.

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) - HL 0.62-0.66, HW 0.44-0.48, CI 71-73, ML 0.07-0.08, MI 11-13, SL 0.32-0.34, SI 68-74 (6 measured). Cephalic dorsum in profile without standing hairs, or at most with a single sparse transverse row close to the occipital margin. In full-face view laterally projecting straight hairs restricted to the dorsolateral margins of the occipital lobes, where 1-3 may occur on each side. Leading edge of scape with apically directed small hairs only, without freely projecting long simple hairs. Dentition discussed in introduction to group. Pronotum marginate dorsolaterally, the dorsum more or less flat transversely; humeral hair straight and simple, projecting laterally; pronotal dorsum without standing hairs. Mesonotal dorsum with 3 pairs of standing simple hairs. Mesopleuron reticulate-punctate. Propodeal spines subtended by broad lamellae. Dorsal (outer) surfaces of middle and hind tibiae with suberect long straight simple projecting hairs, the longest of them distinctly longer than the maximum tibial width. Femora and basitarsi with similar projecting hairs.

Type Material

Bolton (2000) - Holotype worker, paratype workers and queen, TAIWAN: Nantou Hsien, Puli, 12.vii.1982 (M. Terayama); same locality but 20.viii.1987 (S. Kubota & H. Sakai); Kaohsiung Hsien, Liukuei, 17.viii.1987 (H. Sakai) (The Natural History Museum) [examined].

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. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). J. Nat. Hist. 3 33: 1639-1689 (page 1673, combination in Pyramica)
Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 431, redescription of worker)
Brassard, F., Leong, C.-M., Chan, H.-H., Guénard, B. 2020. A new subterranean species and an updated checklist of Strumigenys (Hymenoptera, Formicidae) from Macao SAR, China, with a key to species of the Greater Bay Area. ZooKeys 970: 63–116 (doi:10.3897/zookeys.970.54958).
Brassard, F., Leong, C.-M., Chan, H.-H., Guénard, B. 2021. High diversity in urban areas: How comprehensive sampling reveals high ant species richness within one of the most urbanized regions of the world. Diversity 13, 358 (doi:10.3390/d13080358).
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).
Tang, K.L., Pierce, M.P., Guénard, B. 2019. Review of the genus Strumigenys (Hymenoptera, Formicidae, Myrmicinae) in Hong Kong with the description of three new species and the addition of five native and four introduced species records. ZooKeys 831: 1–48 (DOI 10.3897/zookeys.831.31515).
Terayama, M.; Kubota, S. 1989. The ant tribe Dacetini (Hymenoptera, Formicidae) of Taiwan, with descriptions of three new species. Jpn. J. Entomol. 57: 778-792 (page 788, figs. 23-27 worker, queen described)
Terayama, M.; Lin, C.-C.; Wu, W.-J. 1996. The Taiwanese species of the ant genus Smithistruma (Hymenoptera, Formicidae). Jpn. J. Entomol. 64: 327-339 (page 331, see also)
Wang, C., Lin, C.-C., Keller, R.A., Billen, J. 2021. The ‘hairwheels’ in Strumigenys ants are not glandular. Asian Myrmecology 13: e013004 (doi:10.20362/am.013004).
Wu, J., Wang, C. 1995. The ants of China. Beijing: China Forestry Publishing House, x + 214 pp. (page 67, catalogue)

References based on Global Ant Biodiversity Informatics

Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
Kadoorie Farm and Botanic Garden, 2002. Report of a Rapid Biodiversity Assessment at Qingshitan Headwater Forest Nature Reserve, Northeast Guangxi, China, 25 to 26 August 1998. South China Forest Biodiversity Survey Report Series (Online Simplified Version): No. 17. KFBG, Hong Kong SAR, ii + 12 pp.
Li Z.h. 2006. List of Chinese Insects. Volume 4. Sun Yat-sen University Press
Tang K.L., Pierce M.P., and B. Guénard. 2019. Review of the genus Strumigenys (Hymenoptera, Formicidae, Myrmicinae) in Hong Kong with the description of three new species and the addition of five native and four introduced species records. ZooKeys 831: 1-48.
Terayama M. 2009. A synopsis of the family Formicidae of Taiwan (Insecta: Hymenoptera). Research Bulletin of Kanto Gakuen University. Liberal Arts 17:81-266.
Terayama M., C. C. Lin, and W. J. Wu. 1996. The Taiwanese species of the ant genus Smithistruma (Hymenoptera, Formicidae). Japanese Journal of Entomology 64: 327-339.
Terayama M., and S. Kubota. 1989. The ant tribe Dacetini (Hymenoptera, Formicidae) of Taiwan, with descriptions of three new species. Japanese Journal of Entomology 57: 778-792.
Terayama, M. 2009. A synopsis of the family Formicidae of Taiwan (Insecta; Hymenoptera). The Research Bulletin of Kanto Gakuen University 17: 81-266.
Xu Z. H., and X. G. Zhou. 2004. Systematic study on the ant genus Pyramica Roger (Hymenoptera, Formicidae) of China. Acta Zootaxonomica Sinica 29: 440-450.
Xu Z. and X.-G. Zhou. 2004. Systematic study on the ant genus Pyramica Roger (Hymenoptera, Formicidae) of China. Acta Zootaxonomica Sinica 29(3): 440-450
Xu Z. and X.-G. Zhou. 2004. Systematic study on the ant genus Pyramica Roger (Hymenoptera, Formicidae) of China. Acta Zootaxonomica Sinica 29(3): 440-450.