Strumigenys feae

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).

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.

Distribution based on Regional Taxon Lists
Oriental Region: Cambodia, Myanmar, Thailand, Vietnam. Palaearctic Region: China.

Nomenclature

 *  feae. Strumigenys feae Emery, 1895k: 473 (w.q.) MYANMAR. See also: Bolton, 2000: 882.

Type Material
Syntype workers and queen, BURMA ( = Myanmar): Palon, Pegu, viii-ix.1887 (L. Fea) [examined].

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.

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 based on Global Ant Biodiversity Informatics

 * Alcantara M. J., S. Modi, T. C. Ling, J. Monkai, H. Xu, S. Huang, and A. Nakamura. 2019. Differences in geographic distribution of ant species (Hymenoptera: Formicidae) between forests and rubber plantations: a case study in Xishuangbanna, China, and a global meta-analysis. Myrmecological News 29: 135-145.
 * Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
 * Eguchi K.; Bui T. V.; Yamane S. 2011. Generic synopsis of the Formicidae of Vietnam (Insecta: Hymenoptera), part I  Myrmicinae and Pseudomyrmecinae. Zootaxa 2878: 1-61.
 * Emery C. 1897. Formicidarum species novae vel minus cognitae in collectione Musaei Nationalis Hungarici quas in Nova-Guinea, colonia germanica, collegit L. Biró. Természetrajzi Füzetek 20: 571-599.
 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Li Q., Y. Chen, S. Wang, Y. Zheng, Y. Zhu, and S. Wang. 2009. Diversity of ants in subtropical evergreen broadleaved forest in Pu'er City, Yunnan. Biodiversity Science 17(3): 233-239.
 * 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.
 * Xu Z. 1998. A report of fourty-one ant species newly recorded in China from Xishuangbanna District of Yunnan Province (Hymenoptera: Formicidae). Zhongguo Xue Shu Qi Kan Wen Zhai 4: 1119-1121.
 * Zryanin V. A. 2011. An eco-faunistic review of ants (Hymenoptera: Formicidae). In: Structure and functions of soil communities of a monsoon tropical forest (Cat Tien National Park, southern Vietnam) / A.V. Tiunov (Editor). – M.: KMK Scientific Press. 2011. 277 р.101-124.