Lordomyrma bhutanensis (Baroni Urbani, 1977)

Lordomyrma bhutanensis (Baroni Urbani, 1977) View in CoL

( Figs. 15-20 View Figs View Figs )

Stenamma bhutanense Baroni Urbani, 1977: 420 . Bhutan. Combination in Lordomyrma : Branstetter, 2009: 48. Holotype worker images, non-type workers and queens from southwestern China examined (deposited in SWFU).

Stenamma sinensis Ma, Xu, Makio & DuBois, 2007: 372 View in CoL . China, Shaanxi Province. Combination in Lordomyrma View in CoL : Branstetter, 2009: 49. Five paratype workers examined (deposited in SWFU). Syn. nov.

Description of workers (n=32) ( Figs.15-17 View Figs ): TL 2.9-3.6, HL 0.68-0.87, HW 0.61-0.70, CI 76-90, SL 0.47-0.58, SI 74-85, ED 0.10-0.15, PW 0.41- 0.50, WL 0.83-1.05, PL 0.33-0.45, PH 0.21-0.30, DPW 0.16-0.24, PI 59-69, PPL 0.18-0.28, PPH 0.18-0.28, PPW 0.21-0.28, PPI 91-113.

In full-face view, head roughly square, slightly longer than broad. Posterior margin almost straight, slightly convex laterally and slightly concave in the middle, posterior corners rounded, lateral margins weakly convex. Mandibles subtriangular, masticatory margin with 7-8 teeth. Clypeus longitudinally depressed in the middle, with a pair of anteriorly divergent carinae on the sides of the depression; anterior margin moderately convex, with a tiny median tooth. Antennae 12-segmented, relatively shorter, apices of scapes reach to 9/10 of the distance from antennal sockets to posterior head corners; antennal clubs consist of the apical 3 segments which incrassate apically. Eyes small, located before mid-length of the head sides, with 5 ommatidia on the maximum diameter.

In lateral view dorsal outline of mesosoma sloping posteriorly. Promesonotum moderately convex, promesonotal suture absent. Metanotal groove moderately impressed. Propodeal dorsum nearly straight, rounded anteriorly, posterodorsal corner usually triangularly toothed, sometimes bluntly angled or acutely toothed. Propodeal lobes triangular, with apices acute to blunt. Petiolar node roughly triangular, longer than anterior peduncle, anterior margin almost straight, posterior margin moderately convex, narrowly rounded at apex; anteroventral corner usually bluntly angled, sometimes ventrally toothed or longitudinally prominent as a narrow strip. Postpetiolar dorsum strongly convex and weakly inclined posteriorly, ventral margin straight, anteroventral corner rightly angled. Gaster ovate, sting extruding.

In dorsal view pronotum broadest, lateral margins strongly convex. Promesonotal suture absent. Mesonotum narrowest, lateral margins weakly convex. Metanotal groove impressed. Propodeum widened posteriorly, strongly convex posterolaterally. Petiolar node transverse, about as broad as long, lateral margins weakly convex. Postpetiolar node broader than long, lateral margins strongly convex, broader than petiolar node.

Mandibles longitudinally striate. Head dorsum loosely rugose and divergent posteriorly, posterior margin and sides reticulate-rugose, clypeus relatively smooth. Dorsum of mesosoma reticulate-rugose, longitudinally rugose or irregularly rugose; mesopleuron reticulate-rugose, metapleuron and propodeal sides longitudinally rugose, propodeal declivity transversely rugose. Petiole and postpetiole finely reticulate-rugose, sides of petiole node finely obliquely rugose, sometimes sternites of petiole and postpetiole densely punctured. Gaster smooth and shining. Body dorsum with abundant erect to suberect hairs and abundant subdecumbent to decumbent pubescence, hairs on head dorsum relatively denser and shorter. Scapes and tibiae with dense subdecumbent to decumbent pubescence. Body color usually reddish brown, sometimes yellowish brown or blackish brown, legs brownish yellow.

Description of queens (n=12) ( Figs. 18- 20 View Figs ): TL 4.0-4.6, HL 0.78-0.85, HW 0.68-0.75, CI 84-91, SL 0.53-0.58, SI 73-78, ED 0.18-0.21, PW 0.53-0.70, WL 1.08-1.30, PL 0.38-0.50, PH 0.29- 0.30, DPW 0.20-0.24, PI 60-80, PPL 0.20-0.28, PPH 0.29-0.33, PPW 0.30-0.33, PPI 109-150.

Like workers, but body relatively larger. Eyes relatively larger, vertex with 3 ocelli, rarely ocelli absent. In lateral view mesonotum massive, dorsum horizontal and roughly straight, moderately convex anteriorly, apex of scutellum rounded, tegulae present, mesopleuron with an oblique furrow. Metascutum narrow and oblique, overhung by scutellum. Propodeal dorsum sloping and steep, shorter than declivity, posterodorsal corner triangular toothed or shortly spined, as long as or longer than propodeal lobes. In dorsal view posterior margin of pronotum deeply roundly concave, humeral corners broadly rounded. Mesonotum massive and broadest. Scutum large without longitudinal furrows, posterior margin roundly convex. Lateral scutum small and triangular. Anterior margin of scutellum bluntly angled, posterior margin roundly convex. Sculpture like that of workers, but mesosoma longitudinally rugose, pronotum, propodeal dorsum and declivity transversely rugose. Body dorsum with abundant erect to suberect hairs and dense subdecumbent to decumbent pubescence. Body color reddish brown; head black; mandibles, antennae and legs yellowish brown.

Comparison: In full-face view, the paratype worker of Lordomyrma sinensis ( Fig. 21 View Figs ) has a similarly shaped head capsule, mandibles, clypeus, antennae, and eyes to the holotype worker of L. bhutanensis ( Fig. 15 View Figs ). The head is roughly square with almost straight posterior margin and rounded posterior corners. Clypeus has a pair of anteriorly divergent carinae, anterior margin has a tiny tooth in the center. Mandibles subtriangular, masticatory margin with 7 teeth. Antennal club consisting of the apical 3 segments, apex of scape not reaching posterior head corner. Eyes small, located before midpoint of lateral head margins.

In lateral view, the paratype worker of L. sinensis ( Fig. 22 View Figs ) also has a similarly shaped mesosoma, petiole and postpetiole to the holotype worker of L. bhutanensis ( Fig. 16 View Figs ). The dorsal outline of the mesosoma is sloping posteriorly, promesonotum moderately convex, promesonotal suture absent. Mesonotum raised up posteriorly, metanotal groove moderately impressed. Propodeal dorsum nearly straight, rounded anteriorly, posterodorsal corners shortly dentate and roughly triangular. Propodeal lobes triangular, about as long as propodeal teeth. Petiolar node roughly triangular and weakly inclined posteriorly, anterior margin nearly straight, posterior margin strongly convex, dorsal apex bluntly angled, the node longer than anterior peduncle. Postpetiolar node inclined posteriorly, dorsum roundly convex.

In dorsal view, the paratype worker of L. sinensis ( Fig. 23 View Figs ) shows similar shape in mesosoma, petiole and postpetiole to the holotype worker of L. bhutanensis ( Fig.17 View Figs ). Pronotum broadest with strongly convex lateral margins, promesonotal suture absent. Mesonotum narrowest with roughly straight lateral margins, metanotal groove impressed. Propodeum widened posteriorly with moderately convex lateral margins. Petiolar node roughly square with weakly convex sides. Postpetiolar node broader than petiolar node, with strongly convex sides.

Conclusion: After the above comparison, we could not find any significant phenotypical differences between the two taxa and therefore consider L. sinensis as a junior synonym of L. bhutanensis .

The paratype worker of Lordomyrma sinensis shows similar characters in body surface sculpture, pilosity, color, measurements and indices to the holotype worker of L. bhutanensis . Head dorsum has posteriorly divergent loose rugae which become reticulate-rugose on posterior margin and sides. Clypeus smooth and shining. Mandibles longitudinally striate. Mesosoma reticulate-rugose, metapleuron and propodeal sides longitudinally rugose. Petiole finely obliquely rugose. Postpetiole finely reticulate-rugose. Gaster smooth and shining. Body dorsum with abundant erect to suberect hairs and abundant subdecumbent to decumbent pubescence, head dorsum with relatively denser and shorter hairs. Scapes and tibiae with dense subdecumbent to decumbent pubescence. Body color reddish brown, legs brownish yellow. Both Lordomyrma bhutanensis and L. sinensis have similar ranges in terms of their measurements and indices. Total length ranges between 2.9 mm to 3.4 mm.

Variation: Based on observation of a long series of specimens identified to L. bhutanensis from southwestern China from the year 1999 to 2020, we find that the species shows obvious variation in metanotal groove width, propodeal dorsum, propodeal spines, propodeal lobes, subpetiolar process, sculpture, color and size. Metanotal groove may vary from narrowly to widely impressed. Propodeal dorsum may vary from longer than declivity to as long as declivity. Propodeal spines may vary from bluntly angled, triangularly dentate, to acutely toothed. Propodeal lobes may vary from acutely toothed to bluntly toothed. Subpetiolar process may vary from rightly angled, triangularly toothed, to narrowly prominent as a longitudinal strip. Reticulate-rugose sculpture on mesosomal dorsum sometimes may be irregular or mainly longitudinal, oblique rugae on sides of petiolar node may be strong or relatively weaker. Body color varies from yellowish brown, reddish brown to blackish brown. Total length varies from 2.9 mm to 3.4 mm. Beside the above mentioned variation, the main characters of the species are reliable, including squared head with posteriorly divergent loose rugae on the dorsum, bicarinated clypeus with a tiny central tooth on the anterior margin, relatively shorter antennae with 3-segmented clubs, posteriorly sloping mesosomal dorsum with moderately impressed metanotal groove, roughly triangular petiolar node with relatively shorter anterior peduncle, and distinct rugae on mesosoma and postpetiole.

Geographical range: On the basis of the above assessment, we conclude that L. bhutanensis is a common alpine species widely distributed in the Himalayas , Mt. Hengduanshan , and Mt. Qinling, basically occurring from Bhutan, east to Tibet, Yunnan, Sichuan and Shaanxi in China. The species has an altitudinal range of 1500 m to 3760 m.

Specimens examined: 9 workers: China, Tibet Autonomous Region, Nyingchi County, Lunang Town, Dongjug Village , 29.8859°N, 94.7866°E, 2750 m, collected from a nest inside topsoil in conifer-broadleaf mixed forest, 13.VII.2009, Xueyun Ma leg., No. A 09-1600 GoogleMaps ;

9 workers: China, Tibet Autonomous Region, Nyingchi County, Pelung Town, Zaqu Village , 29.9114°N, 95.1463°E, 2510 m, collected from a nest inside decayed wood in broadleaf forest, 25.IX.2007, Zhenghui Xu leg., No. A 07- 434 GoogleMaps ;

9 workers: China, Tibet Autonomous Region, Bomi County, Zhamo Town, Zhamo Village , 29.8679°N, 95.7272°E, 2960 m, collected from a nest in soil in Pinus densata forest, 24.VII.2011, Nana Yu leg., No. A 11-4295 GoogleMaps ;

9 workers: China, Tibet Autonomous Region, Medog County, Dagmo Town, 70K, 29.7037°N, 95.5224°E, 2750 m, collected from a nest in soil in Abis forest , 27.VII.2011, Chenglin Zhang leg., No. A 11-4193 GoogleMaps ;

9 workers: China, Tibet Autonomous Region, Zayu County, Goyu Town, Bolo Village , 28.9947°N, 97.4006°E, 3000 m, collected from a nest inside litter in conifer-broadleaf mixed forest, 01.IX.2010, Nana Yu leg., No. A 10-3623 GoogleMaps ;

9 workers: China, Tibet Autonomous Region, Zayu County, Zhowagoin Town , Cibagou, 28.7073°N, 97.0430°E, 2610m, collected from a nest inside decayed wood in conifer-broadleaf mixed forest, 10.X.2007, ZhenghHui Xu leg., No. A 07-1141 GoogleMaps ;

9 workers: China, Tibet Autonomous Region, Zayu County, Zhowagoin Town , Cibagou, 28.7073°N, 97.0430°E, 2550 m, collected from a nest inside decayed wood in conifer-broadleaf mixed forest, 10.X.2007, Zhenghui Xu leg., No. A 07-1133 GoogleMaps ;

9 workers: China, Tibet Autonomous Region, Zayu County, Zhowagoin Town, Zayu River side, 28.6032°N, 97.2198°E, 1870 m, collected from a nest under stone in shrub, 7.X.2007, Zhenghui Xu leg., No. A 07-1241 GoogleMaps ;

8 workers: China, Yunnan Province, Lushui County, Pianma Town, Pianma Yakou , 25.9779°N, 98.6975°E, 3000 m, collected from a soil sample in shrub, 27.IV.1999, Zhenghui Xu leg., No. A 99-3 GoogleMaps ;

8 workers, 1 queen: China, Yunnan Province, Lushui County, Pianma Town, Pianma Village , 25.9938°N, 98.6608°E, 2500 m, collected from a nest in soil in subalpine moist broadleaf forest, 25.IV.1999, Zhenghui Xu leg., No. A 99- 28 GoogleMaps ;

3 workers: China, Yunnan Province, Tengchong County, Jietou Town, Er’naozi , 25.6447°N, 98.7354°E, 2500 m, collected from a soil sample in subalpine moist broadleaf forest, 1.V.1999, Zhenghui Xu leg., No. A 99-189 GoogleMaps ;

8 workers, 1 queen: China, Yunnan Province, Deqen County, Yunling Town, Mingyong Village , 28.4594°N, 98.7701°E, 2750 m, collected from a nest in soil in conifer-broadleaf mixed forest, 9.X.2004, Zhenghui Xu leg., No. A 04-525 GoogleMaps ;

8 workers, 1 queen: China, Yunnan Province, Deqen County, Yanmen Town, Tuola Village , 28.0762°N, 98.7526°E, 3030 m, collected from a nest in soil in conifer-broad leaf mixed forest, 17.X.2003, Zhenghui Xu leg., No. A 3970 GoogleMaps ;

9 workers: China, Yunnan Province, Weixi County, Tuozhi Town, Tuozhi Village , 27.1490°N, 99.4010°E, 3000 m, collected from a nest in soil in conifer-broadleaf mixed forest, 12.X.2003, Meizhao Fu leg., No. A 3435 GoogleMaps ;

6 workers: China, Yunnan Province, Lanping County, Lajing Town, Lajing Village , 26.4577°N, 99.3048°E, 3000 m, collected from a soil sample in conifer-broadleaf mixed forest, 8.X.2003, Zhenghui Xu leg., No. A 3211 GoogleMaps ;

8 workers: China, Yunnan Province, Jianchuan County, Diannan Town, Shangguandian Village , 26.3892°N, 99.9392°E, 3000 m, collected from a nest in soil in Pinus yunnanensis forest, 1.XI.2005, Shengli Shi leg., No. A 05-1357 GoogleMaps ;

1 worker: China, Yunnan Province, Dali City, Dali Town, Mt. Cangshan , 25.6842°N, 100.1071°E, 3250 m, collected from a ground sample in conifer-broadleaf mixed forest, 29.X.2005, Xiao Guo leg., No. A 05-978 GoogleMaps .

3 workers: China, Yunnan Province, Yulong County, Shitou Town, Mount Jinsishan , 26.8325°N, 99.6272°E, 3250 m, collected from a soil sample in conifer-broadleaf mixed forest, 19.X.2004, Xiao Guo leg., No. A 04-1137 GoogleMaps ;

9 workers: China, Yunnan Province, Yulong County, Baisha Town, Yulong Snow Mountain , 27.1349°N, 100.2598°E, 3000 m, collected from a nest in soil in Pinus yunnanensis forest, 20.X.2004, Zhenghui Xu leg., No. A 04- 1208 GoogleMaps ;

5 workers: China, Sichuan Province, Danba County, Dongkor Town, Kuiyong , 30.5172°N, 101.7858°E, 3380 m, collected on the ground in Quercus forest, 24.VIII.2005, Zhenghui Xu leg., No. A 05-522 GoogleMaps ;

9 workers: China, Sichuan Province, Muli County, Ke’er Town, Cunduohai , 28.1251°N, 101.1613°E, 3760 m, collected from a nest in soil in Quercus shrub, 29.VII.2018, Xinmin Zhang leg., No. C 18-1257 GoogleMaps ;

9 workers: China, Sichuan Province, Muli County, Ke’er Town, Zhongniuchang , 28.1026°N, 101.1477°E, 3250 m, collected from a nest in soil in Quercus forest, 29.VII.2018, Xinmin Zhang leg., No. C 18-1349 GoogleMaps ;

9 workers: China, Sichuan Province, Muli County, Liziping Town, Mahuanggou , 28.0875°N, 101.1726°E, 3040 m, collected from a nest in soil in Pinus yunnanensis forest, 30.VII.2018, Yucheng He leg., No. C 18-1386 GoogleMaps ;

4 workers: China, Sichuan Province, Muli County, Xiamaidi Town, Mianbuyakou , 27.6873°N, 101.2211°E, 3280 m, collected from a soil sample in alpine conifer forest, 26.VII.2018, Zhao Huang leg., No. C 18-796 GoogleMaps ;

9 workers: China, Sichuan Province, Yanyuan County, Mianya Town, Mianya Village , 27.6352°N, 101.2508°E, 2800 m, collected from a nest in soil in conifer-broadleaf mixed forest, 26.VII.2018, Zhao Huang leg., No. C 18-706 GoogleMaps ;

2 workers: China, Sichuan Province, Chongzhou City, Jiguanshan Town, Maliugou , 30.7974°N, 103.2277°E, 1600 m, collected under a decayed wood in broadleaf forest, 18.VI.2016, Zhenghui Xu leg., No. A 16-337 GoogleMaps ;

2 workers: China, Sichuan Province, Chongzhou City, Jiguanshan Town, Maliugou , 30.7974°N, 103.2277°E, 1500 m, collected on the ground in broadleaf forest, 18.VI.2016, Zhenghui Xu leg., No. A 16-304 GoogleMaps ;

1 worker: China, Sichuan Province, Pingwu County, Baima Town, Suoguxiu Village , 32.7345°N, 104.3459°E, 2050 m, collected from a soil sample in conifer-broadleaf mixed forest, 25.VII.2017, Biao Qi leg., No. A 17-998 GoogleMaps ;

9 workers: China, Sichuan Province, Pingwu County, Muzuo Town, Muzuo Village , 32.7118°N, 104.3902°E, 1770 m, collected from a nest under stone in semi-evergreen broadleaf forest, 26.VII.2017, Biao Qi leg., No. A 17-1103 GoogleMaps ;

5 paratype workers of Lordomyrma sinensis : China, Shaanxi Province, Mt. Qinling , 33.6500°N, 107.8000°E, 1580-1640 m, collected from litter in forest land, 07-18.IX.2005, Libin Ma leg. GoogleMaps

Distribution and ecology: China (Tibet, Yunnan, Sichuan, Shaanxi (Type locality of L. sinensis )), Bhutan (type locality of L. bhutanense ), Nepal. The species uses various habitats, such as semi-evergreen broadleaf forest, subalpine moist broadleaf forest, conifer-broadleaf mixed forest, alpine conifer forest and shrublands, often nesting in soil, decayed wood, leaf litter or under stone. Most individuals forage on the ground or in leaf litter and tend to be shy when disturbed.