Strumigenys feae

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Strumigenys feae
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. feae
Binomial name
Strumigenys feae
Emery, 1895

Strumigenys feae casent0280748 p 1 high.jpg

Strumigenys feae casent0280748 d 1 high.jpg

Specimen Labels

Synonyms

A specimen was collected from litter in a limestone substrate rainforest. In Hong Kong, it has been collected within tree plantations of Lophostemon confertus Wilson & Waterh. and in secondary forests, with elevation ranging from 138 to 457 m (Tang et al., 2019). Tang & Guenard (2023) report it as occurring in primary forest, secondary forest, mature forest and rubber plantation. Known elevation from 140 to 525 m.

Identification

Bolton (2000) - A member of the feae complex in the Strumigenys mayri-group. Resembling Strumigenys exilirhina in almost all characters but feae with a very much smaller preapical tooth on the mandible. In feae this tooth is short and narrow (may be denticle-like) and its length is at most only one-quarter of the width of the mandible at the point where the tooth arises. In exilirhina the preapical tooth is stoutly triangular and its length approaches the width of the mandible at the point where the tooth arises.

  • Tang & Guenard (2023), Fig. 17. New species records of Strumigenys in full-face, profile and dorsal views. A–C. Worker of S. emmae from Thailand (ANTWEB1011939). D–F. Worker of S. exilirhina from Hainan, mainland China (HNA-00471). G–I. Worker of S. feae from Hainan, mainland China (HNA-01127).
  • Tang & Guenard (2023), Fig. 18. Mandible close-ups of sibling species of Strumigenys from the feae-complex of the S. mayri-group. A. Syntype worker of S. formosensis before synonymization. B–C, F. Workers of S. feae from Hainan, mainland China. D. Syntype worker of S. feae. E. Worker of S. feae from Hong Kong. G–H. S. cf. feae from Vietnam. I. S. exilirhina from Hainan, mainland China. A. CASENT0909309, from AntWeb, taken by Zach Lieberman. B. HNA-01503. C. HNA-01127. D. CASENT0904951, from AntWeb, taken by Will Ericson. E. RHL01266. F. HNA-01520. G. CTS13-4m2-sp15. H. NN-S69-sp18-W1. I. HNA-00471.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 22.43681° to 11.91666667°.

 
North
Temperate 		North
Subtropical 		Tropical South
Subtropical 		South
Temperate

Distribution based on Regional Taxon Lists

Oriental Region: Cambodia, Myanmar (type locality), Pakistan, Taiwan (type locality), Thailand, Vietnam.
Palaearctic Region: China, Japan.

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

Castes

Worker

Images from AntWeb

Strumigenys feae casent0904951 h 1 high.jpgStrumigenys feae casent0904951 p 1 high.jpgStrumigenys feae casent0904951 d 1 high.jpgStrumigenys feae casent0904951 l 1 high.jpg
Syntype of Strumigenys feae. Worker. Specimen code casent0904951. Photographer Will Ericson, uploaded by California Academy of Sciences. Owned by MSNG, Genoa, Italy.
Strumigenys feae H RHL01266.jpg
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Strumigenys formosensis casent0280747 h 1 high.jpgStrumigenys formosensis casent0280747 p 1 high.jpgStrumigenys formosensis casent0280747 d 1 high.jpgStrumigenys formosensis casent0280747 l 1 high.jpg
Worker. Specimen code casent0280747. Photographer Shannon Hartman, uploaded by California Academy of Sciences. Owned by NHMUK, London, UK.

Nomenclature

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

  • feae. Strumigenys feae Emery, 1895k: 473 (w.q.) MYANMAR.
    • Status as species: Bolton, 2000: 882.
  • formosensis. Strumigenys feae var. formosensis Forel, 1912a: 52 (w.) TAIWAN.
    • Brown, 1949d: 24 (q.).
    • Raised to species: Brown, 1949d: 19.
    • Status as species: Terayama & Kubota, 1989: 781; Bolton, 2000: 884.
    • Junior synonym of feae: Tang & Guenard, 2023: 53.

Type Material

Strumigenys feae: Syntype workers and queen, BURMA ( = Myanmar): Palon, Pegu, viii-ix.1887 (L. Fea) (Museo Civico di Storia Naturale, Genoa, Naturhistorisches Museum Wien, Vienna).

Strumigenys feae formosensis: Syntype workers, TAIWAN: Pilam (H. Sauter) (Musee d'Histoire Naturelle Genève).

Taxonomic Notes

Tang et al. (2019): While S. formosensis (Forel, 1912) has been recorded from Hong Kong (Bolton 2000), we consider these records as S. feae. Strumigenys formosensis was initially described as a subspecies of S. feae, and Brown (1949: 24) raised S. formosensis to the species level without strong justification and without examining specimens of S. feae, writing: “Although I have seen no specimens of Emery’s Burmese species feae, I am arbitrarily raising the Taiwan form to species rank.”, on the basis of Forel’s description of S. formosensis having small propodeal teeth and a strongly concave posterior mesosomal dorsum, with this latter information absent in Emery’s description of S. feae. The examination of the pictures of the type specimen of S. feae available on AntWeb (CASENT0904951), however, show the presence of a concavity between the mesonotum and propodeum, and with propodeal spines of the type of S. formosensis (CASENT0909309) indistinctly smaller than S. feae.

The revised descriptions of S. feae and S. formosensis by Bolton (2000) also revealed no clear distinction between them except the difference in morphological measurements, the length and morphology of the preapical teeth (“not directed medially but instead so strongly inclined toward the apicodorsal tooth that its proximal margin forms a single continuous line with the inner mandibular margin” for S. formosensis), and brief mentioning of the maximum diameter of the eye compared to the width of the scape (“slightly greater” for S. feae and “equal to or slightly less” for S. formosensis), with the rest of the descriptions almost identical to one another.

Specimens collected in Hong Kong could not be assigned to either S. feae or S. formosensis without ambiguity under the current descriptions. Preapical teeth are neither fully directed medially as in S. feae, nor with a single continuous proximal margin as in S. formosensis (Fig. 3). Morphological measurements also give little additional information. Measurements of the specimen ANTWEB1017082 (Fig. 3A), which has more forward-inclined preapical teeth, fall within the norm of S. formosensis as expected, specimen RHL01266 (Fig. 3B) with more medially-directed preapical teeth has some of its measurements closer to S. formosensis than to S. feae (Table 1). Considering the fact that S. formosensis was raised to its current species level somewhat arbitrarily, the validity of S. formosensis as a species would require further investigation using specimens from a wider geographic range than is available for this study.

Tang & Guenard (2023) - The species status of S. formosensis, which was initially raised from being a subspecies of S. feae to species level by Brown “arbitrarily” (1949: 19) and without examining any specimen of S. feae, was questioned in Tang et al. (2019) based on specimens from Hong Kong. Observable morphological differences between S. feae and S. formosensis from pictures of the type specimens is limited to the morphology of the preapical teeth; the same can also be applied to the revised descriptions by Bolton (2000). Here, we report that assessment of the specimens from Hainan resulted in a similar observation as in Tang et al. (2019). Morphotypes cannot be definitely delimited into one with a medially directed preapical tooth and another one with a preapical tooth in line with the inner margin of the mandible. Instead, specimens collected from various locations in Hainan (and Hong Kong) presented a continuum between the two extremes (Fig. 18B–C). Preapical teeth with various sizes and mandibles with differences in morphology are also observed. Some individuals have slightly broader mandibles and more irregular outlines (Fig. 18B–C), while others have slightly narrower mandibles and straighter outlines (Fig. 18E–F). But these are not two distinct morphotypes, and, like preapical tooth morphology, there are intermediary forms in-between the two extremes. Hence, based on current evidence, S. feae is a species with a considerable variation in preapical tooth and mandible morphology. Strumigenys formosensis should be, once again, considered as a junior synonym of S. feae. Consequently, after this synonymization and the report of new records from Hainan Province of mainland China and Satsunan Islands of Japan, S. feae has an almost-continuous distribution within Asia ranging from Taiwan to Thailand and Myanmar, with only Fujian and Guangdong provinces of mainland China and Laos lacking records for this species, but it is very likely to be also present there.

Bolton (2000) mentioned that Strumigenys exilirhina “series from Thailand tend to have the preapical tooth slightly smaller and somewhat closer to the apicodorsal tooth than in material from elsewhere”. Our specimens collected from both northeast and southern Thailand as well as Vietnam display a similar morphology (Fig. 18G–H). In fact, upon close inspection and after direct comparison with specimens of S. exilirhina from southern China (Fig. 18I), in addition to the size and placement of the preapical tooth, there are other morphological differences between them. The overall inner margin of the mandible of S. exilirhina, before and after where the preapical tooth arises, shows a continuous contour; the preapical tooth is also well differentiated from the inner margin by an angle both in front and after the tooth. On the other hand, the inner margin of the mandible in specimens from the Indochinese Peninsula does not show a continuous contour due to a marked change in mandible width before and after where the tooth arises; the inner margin of the mandible evenly grading into the preapical tooth at the basal end, the tooth is only well differentiated from the inner margin by an angle at the apical end (Fig. 18G). Both of these put Indochinese specimens closer to S. feae than to S. exilirhina. In contrast to the distinctively curvilinear mandibles of S. exilirhina from southern China, Indochinese specimens have a rather straight inner margin of the mandible, similar to typical S. feae. Hence, they are closer to S. feae than to S. exilirhina considering their overall mandible morphology. We thus consider that it is more appropriate for Indochinese specimens to be temporarily considered as S. feae based on the current diagnosis of the species. It is possible that they constitute a separate species, but a delimitation based on mandible morphology solely appears to be difficult. The first challenge would be to clearly differentiate between S. feae (Fig. 18A–F) and feae-like Indochinese specimens (Fig. 18G). There are also a handful of Indochinese specimens (Fig. 18H) that bridge feae-like morphotypes and S. exilirhina, which further complicates the issue.

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

Description

Worker

TL 2.6-2.8, HL 0.75-0.80, HW 0.47-0.52, CI 62-68, ML 0.33-0.36, MI 41-46, SL 0.48-0.50, SI 94-102, PW 0.27-0.28, AL 0.72-0.80 (8 measured).

Characters of the feae-complex. Preapical tooth very small and narrowly triangular, reduced almost to a denticle in some; length of preapical tooth one-quarter or less of the width of the mandible at the point where the tooth arises. Outer margin of mandible in full-face view straight to extremely shallowly convex from close to base to level of preapical tooth; inner margin almost or quite straight. Upper scrobe margin with two freely laterally projecting long flagellate hairs, the posterior one in apicoscrobal position. Cephalic dorsum with 4-6 erect sub flagellate or looped hairs along the occipital margin, a similar but shorter pair at level of highest point of vertex. Preocular notch absent but ventrolateral margin of head narrowed immediately in front of eye. Maximum diameter of eye slightly greater than maximum width of scape; usually 4 ommatidia across the greatest diameter. Pronotal humeral hair flagellate; pronotal dorsum finely, sometimes superficially, reticulate-punctate and without erect hairs. Mesonotum with 2 pairs of erect flagellate hairs. Dorsal surfaces of waist segments and first gastral tergite with flagellate hairs. Pleurae and side of propodeum smooth. One or two long fine erect flagellate hairs present on the dorsal (outer) surface of the hind basitarsus and 1-2 on the hind tibia; similar pilosity present on the other legs. Petiole in profile with anterior face of node slightly shorter than length of dorsum. Disc of postpetiole smooth. Basigastral costulae about equal in length to disc of postpetiole.

References

References based on Global Ant Biodiversity Informatics

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  • Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
  • Brown W. L., Jr. 1949. Revision of the ant tribe Dacetini. I. Fauna of Japan, China and Taiwan. Mushi 20: 1-25.
  • Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
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