Strumigenys feae Emery, 1895

Tang, Kit Lam & Guénard, Benoit, 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, pp. 1-144 : 53-55

Strumigenys feae Emery, 1895

Fig. 17G–I ; Table 2

Strumigenys feae Emery 1895: 473 (w.q.) MYANMAR. Indomalaya.

Strumigenys feae var. formosensis Forel, 1912: 52 . Syn. nov.

Material examined

MAINLAND CHINA – Hainan Province • 1 worker; Bawangling, BWLP8; 19.09125° N, 109.20155° E; 3 Jul. 2016; L. Wang leg.; Winkler , 12 random; IBBL • 2 workers; Bawangling, BWLR7; 19.19498° N, 109.02010° E; 15 Jul. 2016; L. Wang leg.; Winkler , 12 random; IBBL • 3 workers; Bawangling, BWLS11; 19.11678° N, 109.14003° E; 10 Jul. 2016; L. Wang leg.; Winkler , 4 corners; IBBL • 4 workers; same collection data as for preceding; Winkler, 12 random; IBBL • 4 workers; Bawangling, BWLS12; 19.11796° N, 109.13055° E; 15 Jul. 2016; L. Wang leg.; Winkler , 4 corners; IBBL • 6 workers; Bawangling, BWLS2; 19.09193° N, 109.18389° E; 6 Jul. 2016; L. Wang leg.; Winkler , 12 random; IBBL • 1 worker; Bawangling, BWLS4; 19.09674° N, 109.17778° E; 30 Jun. 2016; L. Wang leg.; Winkler , 4 corners; IBBL • 4 workers; Bawangling, BWLS5; 19.10036° N, 109.17835° E; 7 Jul. 2016; L. Wang leg.; Winkler , 4 corners; IBBL • 1 worker; Bawangling, BWLS9; 19.08973° N, 109.19127° E; 9 Jul. 2016; L. Wang leg.; Winkler , 12 random; IBBL • 4 workers; Jianfengling, JFLFW1; 19.117° N, 109.152° E; 24 Dec. 2015; L. Wang leg.; Winkler , 4 corners; IBBL • 1 worker; same collection data as for preceding; Winkler, 12 random; IBBL • 1 worker; Jianfengling, JFLFW3; 19.121° N, 109.118° E; 26 Dec. 2015; L. Wang leg.; Winkler , 4 corners; IBBL • 3 workers; Jianfengling, JFLFW5; 18.697° N, 108.849° E; 4 Jan. 2016; L. Wang leg.; Winkler , 4 corners; IBBL • 1 worker; same collection data as for preceding; Winkler, 12 random; IBBL .

HONG KONG • 1 worker; Tai Po District , Tai Om; 29 Sep. 2007; J. Fellowes leg.; HKBM .

JAPAN – Satsunan Islands • 2 workers; Yonaguni Jima, Mandabaru; 11 Mar. 2020; Sk. Yamane leg.; hand collection; KUM JP20 -SKY-31 .

THAILAND – Bueng Kan Province • 1 queen; 17.84663° N, 103.94113° E; 178 m a.s.l.; 20 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 worker; 17.84684° N, 103.93899° E; 179 m a.s.l.; 20 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 worker; 17.84731° N, 103.93766° E; 181 m a.s.l.; 20 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 queen; 17.85925° N, 103.92703° E; 172 m a.s.l.; 20 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL . – Kalasin Province • 1 queen; 16.80766° N, 103.88383° E; 525 m a.s.l.; 17 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL . – Kanchanaburi Province • 1 queen; Srinakarin Dam National Park ; 150– 200 m a.s.l.; 29 Jun. 2002; Sk. Yamane leg.; KUM . – Sakon Nakhon Province • 1 worker, 1 queen; 17.0907° N, 103.9799° E; 327 m a.s.l.; 18 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 3 workers, 1 queen; 17.11857° N, 104.00355° E; 405 m a.s.l.; 18 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 19 workers, 4 queens; 17.12902° N, 104.00193° E; 484 m a.s.l.; 21 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 7 workers; 17.13092° N, 104.00115° E; 469 m a.s.l.; 21 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 26 workers; same collection data as for preceding; IBBL . – Trang Province • 1 worker, 1 queen; Khao Chong ; 7.25423° N, 99.71394° E; 29 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 4 workers, 1 queen; Khao Chong ; 7.25533° N, 99.71729° E; 29 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 14 workers, 1 queen; Khao Chong ; 7.26393° N, 99.66812° E; 28 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 2 workers; Khao Chong ; 7.26806° N, 99.65777° E; 28 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 2 workers; Khao Chong ; 7.27155° N, 99.65874° E; 28 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 queen; Khao Chong ; 7.27201° N, 99.65614° E; 28 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 worker; Khao Chong ; 7.27201° N, 99.65614° E; 28 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 2 workers; Khao Chong ; 7.54197° N, 99.79446° E; 30 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 3 workers; Khao Chong ; 7.54246° N, 99.79651° E; 25 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 worker; Khao Chong ; 7.54309° N, 99.80029° E; 25 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 worker; Khao Chong ; 7.5436° N, 99.8067° E; 27 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 2 workers; Khao Chong ; 7.54395° N, 99.80502° E; 27 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 6 workers; Khao Chong ; 7.54496° N, 99.80184° E; 27 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 worker; Khao Chong ; 7.54525° N, 99.79203° E; 26 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 4 workers; same collection data as for preceding; IBBL • 12 workers; Khao Chong ; 7.54692° N, 99.79557° E; 30 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 6 workers; Khao Chong ; 7.54765° N, 99.78864° E; 26 Dec. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 2 workers; Khao Chong ; 7.55471° N, 99.78834° E; 1 Jan. 2019; Winkler, 4 corners; IBBL • 1 worker; Khao Chong ; 7.55487° N, 99.7865° E; 1 Jan. 2019; Winkler, 4 corners; IBBL • 4 workers; Khao Chong ; 7.55521° N, 99.79266° E; 1 Jan. 2019; Winkler, 4 corners; IBBL • 2 workers; Khao Chong ; 7.55602° N, 99.78968° E; 1 Jan. 2019; Winkler, 4 corners; IBBL • 1 worker, 1 queen; Khao Chong ; 7.55606° N, 99.78436° E; 1 Jan. 2019; Winkler, 4 corners; IBBL .

VIETNAM – Đắk Nông Province • 2 workers; Nam Nung Reserve ; 12.22927° N, 107.83662° E; 805 m a.s.l.; 12 Jun. 2018; IBBL members leg.; Winkler; IBBL • 8 workers; Nam Nung Reserve ; 12.23025° N, 107.83087° E; 886 m a.s.l.; 12 Jun. 2018; IBBL members leg.; Winkler; IBBL • 2 workers; Nam Nung Reserve ; 12.23077° N, 107.83063° E; 909 m a.s.l.; 12 Jun. 2018; IBBL members leg.; Winkler; IBBL • 2 workers, 1 queen; Nam Nung Reserve ; 12.23113° N, 107.83153° E; 907 m a.s.l.; 12 Jun. 2018; IBBL members leg.; Winkler; IBBL • 4 workers; Nam Nung Reserve ; 12.23077° N, 107.83045° E; 911 m a.s.l.; 12 Jun. 2018; IBBL members leg.; Winkler; IBBL. – Đỗng Nai Province • 7 workers, 1 queen; Cat Tien National Park ; 11.44912° N, 107.35963° E; 140 m a.s.l.; 4 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 worker; Cat Tien National Park ; 11.45298° N, 107.36467° E; 174 m a.s.l.; 4 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 2 workers; Cat Tien National Park ; 11.45683° N, 107.36852° E; 175 m a.s.l.; 4 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 queen; Cat Tien National Park ; 11.36548° N, 197.49062° E; 170 m a.s.l.; 7 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 queen; Cat Tien National Park ; 11.36651° N, 107.49233° E; 169 m a.s.l.; 7 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 1 queen; Cat Tien National Park ; 11.370325° N, 107.513384° E; 172 m a.s.l.; 7 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL • 2 workers; Cat Tien National Park ; 11.45688° N, 107.36958° E; 175 m a.s.l.; 4 Jun. 2018; IBBL members leg.; Winkler, 4 corners; IBBL .

Measurements

Workers

TL 3.0–3.5, HL 0.78–0.92, HW 0.52–0.60, MandL 0.37–0.41, SL 0.51–0.57, EL 0.054 –0.072, PW 0.26– 0.31, ML 0.78–0.90, PL 0.29–0.36, PH 0.13–0.16, DPW 0.12–0.14, PPL 0.16–0.21, GL 0.54–0.74, CI 64–66, MI 44–49, SI 92–100, OI 10–13, LPI 43–48, DPI 36–43 (n=13).

Geographic range

Cambodia, mainland China (Guangxi, Hainan, Hong Kong, Macau, Yunnan), Japan (Satsunan Islands), Myanmar, Pakistan, Taiwan, Thailand, Vietnam.

New record for Guangxi, Hainan, Japan and Taiwan.

Ecology

Collected in primary forest, secondary forest, mature forest and rubber plantation. Known elevation from 140 to 525 m.

Comments

The species status of S. formosensis syn. nov., 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 syn. nov. 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 syn. nov. 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 S. 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.

Figures

Fig. 17. New species records of Strumigenys Smith, 1860 in full-face, profile and dorsal views. A–C. Worker ofS. emmae Emery, 1890 from Thailand (ANTWEB1011939).D–F. Worker ofS. exilirhina Bolton, 2000 from Hainan, mainland China (HNA-00471). G–I. Worker of S. feae Emery, 1895 from Hainan, mainland China (HNA-01127).

Fig. 18. Mandible close-ups of sibling species of Strumigenys Smith, 1860 from the feae-complex of the S. mayri-group. A. Syntype worker of S. formosensis syn. nov. before synonymization. B–C, F. Workers of S. feae Emery, 1895 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. CT- S13-4m2-sp15. H. NN-S69-sp18-W1. I. HNA-00471.