Strumigenys benten

Strumigenys benten
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Attini
Genus:	Strumigenys
Species:	S. benten
Binomial name
	Strumigenys benten; (Terayama, Lin & Wu, W.-J., 1996) Specimen labels

Common Name

Iga-uroko-ari
Language:	Japanese

The species nests at the margins of broadleaf forests and adjacent open land where it nests in the soil or under stones and sampled in Berlese funnel forest-litter samples. A colony collection (Takatsuki, Osaka Prefecture, Japan) was found under a concrete stone among thinly spaced trees on the precints of a temple. It included more than 150 workers (Ogata & Onoyama, 1998). It is most common in the southern part of Honshu south to Kyushu (Japanese Ant Image Database).

Identification

Tang and Guénard (2023) - A member of the elegantula complex in the Strumigenys leptothrix-group.

Bolton (2000) - This species is very closely related to Strumigenys alecto but has the differences tabulated below. The two may eventually prove to be extreme variants of a single species (Ogata & Onoyama, 1998). Strumigenys formosimonticola may also be involved in the variation as Touyama (1998) has documented some interesting pilosity variants that he includes under benten. Until more material is available I regard the following features as being diagnostic of two separate but sibling species, because the distribution and density of specialised pilosity is usually fairly stable in Pyramica species.

S. alecto: With head in profile the dorsum with short erect simple hairs at, in front of and behind the highest point of the vertex. With the head in occipital view 20 or more short erect hairs visible on dorsum. Dorsal (outer) surfaces of middle and hind tibiae with numerous short straight projecting simple suberect hairs. Pronotal dorsum with short erect hairs present anteriorly other than those at the humeri. Pronotal dorsum finely reticulate-punctate.

S. benten: With head in profile the dorsum with short erect hairs only behind highest point of the vertex. With the head in occipital view no more than 8-10 short erect hairs visible on dorsum. Dorsal (outer) surfaces of middle and hind tibiae with apically directed appressed hairs only. Pronotal dorsum without erect hairs except at the humeri. Pronotal dorsum not reticulate-punctate.

Japan

The species is similar to Strumigenys leptothrix, but distinguished by its pilosity: the hairs on the head of S. benten are shorter, more sparse and somewhat clavate, and those on the anterior portion, in particular, are depressed. It should be noted that the pilosity of S. benten is variable. Samples from the Kanto District tend to have shorter, more sparse hairs on the head than those from Kyushu, where the hairs are longer and more dense. The first gastral segment sometimes lacks hairs. (Japanese Ant Image Database)

Touyama (1998) reported that hairs on the vertex may be often lacking in S. benten. Bolton (2000) described the hairless form as a separate new species named Strumigenys alecto. We believe the separate specific status of "alect" from S. benten to be questionable, requiring further study. For this reason we do not recognize S. alecto at this time.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 33.8446° to 30.359°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: AntMaps

Distribution based on Regional Taxon Lists

Oriental Region: Taiwan (type locality).
Palaearctic Region: Japan.

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

Life History Traits

Mean colony size: 150 (Ogata & Onoyama, 1998)

Castes


.

Nomenclature

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

benten. Smithistruma benten Terayama, Lin & Wu, 1996: 329, figs. 1-5, 20 (w.q.) TAIWAN. Combination in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 116. 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) - TL 2.1- 2.6, HL 0.60-0.65, HW 0.44-0.50, CI 71-82, ML 0.13-0.17, MI 13-15 [measurement in Terayama, Lin & Wu (1996: 330) of MI 21-28, is too high; from specimens examined and their fig. 1, MI should be as above], SL 0.26-0.32, SI 59, PW 0.26-0.33, AL 0.65-0.72. Terayama, Lin, & Wu, (1996: 330) give a total dental count of 12 for benten but a specimen with mandibles ajar that I have examined had 14.]

Type Material

Bolton (2000) - Holotype worker and paratype workers and queens, TAIWAN: Nantou Hsien, Lienhuachih, 12.xi.1992 (C.-C. Lin). Paratype workers and queens, TAIWAN: Nantou Hsien, Taping-Meitzulin, ca 510 m., 30.vii.1988 (M. Terayama). JAPAN: Okinawa Pref., Ryukyu Is, Iriomote-jima I., 30.iii.1991 (M. Terayama); Mie Pref., Yokkaichi-shi, 21.iv.1987 (A. Amagasu); Mie Pref., Komono-machi, xii.1989 (M. Terayama); Komaba, Meguro-ku, Tokyo, 30.vi.1986 (M. Terayama); Tokyo, Nakano-ku, 19.viii.1980 (S. Kubota) (National Institute of Agro-Environmental Sciences, National Science Museum (Natural History), National Taiwan University, Taiwan Agricultural Research Institute) [NSMT paratypes examined].

References

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Bolton, B. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). Journal of Natural History. 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)
Hisasue, Y. 2018. Ant fauna of Matsuyama Castle. ARI 39: 18-36.
Ogata, K. and Onoyama, K. 1998. A revision of the ant genus Smithistruma Brown of Japan, with descriptions of four new species (Hymenoptera: Formicidae). Entomological Science. 1(2):277-287.
Park, S.-H., Hosoishi, S., Ogata, K., Kasuya, E. 2014. Changes of species diversity of ants over time: A case study in two urban parks. Journal of the Faculty of Agriculture, Kyushu University 59(1), 71–76.
Park, S.-H., Hosoishi, S., Ogata, K., Kuboki, Y. 2014. Clustering of ant communities and indicator species analysis using self-organizing maps. Comptes Rendus Biologies 337, 545–552 (doi:10.1016/j.crvi.2014.07.003).
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).
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 329, figs. 1-5, 20 worker, queen described)
Touyama, Y. 1998. Report on the interesting variation of Smithistruma benten in the vicinity of Hiroshima City. Edaphologia 61:1-5.
Touyama, Y., Yamamoto, T., Nakagoshi, N. 1998. Myrmecofaunal change with bamboo invasion into broadleaf forests. Journal of Forestry Research 3: 155-159.
Wang, C., Chung, F.-Y., Lin, C.-C., Gibson, J. C., McGuire, S., Suarez, A. V., Billen, J. 2023. The spongiform tissue in Strumigenys ants contains exocrine glands. Arthropod Structure & Development 73, 101246 (doi:10.1016/j.asd.2023.101246).
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).

References based on Global Ant Biodiversity Informatics

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