Leptanillinae, Saroj & Mandi & Dubey, 2022

Saroj, Sheela, Mandi, Arnab & Dubey, Anil Kumar, 2022, A new species of the rare ant genus, Leptanilla Emery (Hymenoptera: Formicidae) from Eastern Himalaya, India, Asian Myrmecology (e 015005) 15, pp. 1-9 : 7-8

Key to Oriental Leptanillinae based on workers (Modified from Leong et al 2018)

1) Masticatory margin of mandible with 2 teeth.. ............................................................................2

- Masticatory margin of mandible with 3 or more teeth.................................................................... 3

2) Anterolateral lobes of clypeus present. 3rd antennal segment with a distinct basal peduncle; dorsal view of petiolar node with arched anterior margin; promesonotal suture narrow ( Indonesia) .................................. L. kebunraya Yamane & Ito

- Anterolateral lobes of clypeus absent. 3rd antennal segment without distinct basal peduncle; dorsal view of petiolar node rectangular; promesonotal suture wide ( Malaysia)................. L. butteli Forel

3) Masticatory margin of mandible with 4 teeth.. ............................................................................4

- Masticatory margin of mandible with 3 teeth.... ............................................................................6

4) In full face view 3rd abdominal tergum strongly narrow in its anterior part; basal tooth of masticatory margin of mandible distinct........................5

- In full face view 3rd abdominal tergum weakly narrow in its anterior part; basal tooth of masticatory margin of mandible very small and difficult to distinguish ( Japan) ........................................... .................................... L. japonica Baroni Urbani

5) Post petiole trapezium shaped and posteriorly truncated ( Japan) .......... L. tanakai Baroni Urbani

- post petiole with equal width at anterior and posterior margin; posteriorly not truncate ( India) ..... .................................................. L. ujjalai sp. nov.

6) Metanotal groove present ..............................7

- Metanotal groove absent..................................8

7) In full-face view head approximately rectangular; clypeus not protruding, with anterior margin roundly convex; in profile, dorsum of petiole almost straight; in dorsal view post petiolar node much wider than petiolar node. Smaller species; HW: ca. 0.180 mm ( China) .................................. ............................ L. hunanensis Tang, Li & Chen

- In full-face view head distinctly narrowed anteriorly; clypeus protruding, with anterior margin concave; in profile, dorsum of petiole roundly convex; in dorsal view post petiolar node as wide as petiolar node. Larger species; HW: ca. 0.370 mm ( China) .................. L. kunmingensis Xu & Zhang

8) Anterior margin of clypeus more or less straight or weakly to strongly convex............................. 9

- Anterior margin of clypeus medially incised, bilobed.............................................................. 15

9) Clypeus not protruding anteriorly, and with straight or weakly convex anterior clypeal lobe .. .......................................................................... 10

- Clypeus slightly or strongly protruding anteriorly, and with distinctly convex anterior clypeal lobe...................................................................13

10) Ventral margin of petiolar sternite in lateral view without well developed projection ( Japan). ...................................... L. kubotai Baroni Urbani

- Ventral margin of petiolar sternite in lateral view with well developed and convex projection..... 11

11) Petiolar node distinctly wider than long (PI ≥

138) .................................................................. 12

- Petiolar node distinctly longer than wide (PI ≤ ca. 81) ( Japan) ............... L. morimotoi Yasumatsu

12) Post petiolar node wider than long (PPI = 163–

171). Larger species; HW: ca. 0.235 mm ( China) ................................................ L. yunnanensis Xu

- Post petiolar node almost as long as wide (PPI =

88). Smaller species; HW: ca. 0.140 mm ( Japan) L. okinawensis Terayama

13) Larger species, with petiole longer than 0.13 mm ( Sri Lanka) ......... L. besucheti Baroni Urbani

- Smaller species, with petiole shorter than 0.10 mm ...................................................................14

14) Ventral margin of petiolar sternite with triangular projection. Subpetiolar process absent. PPI = 122–138; CI ≥ 82; PI = 111–125 ( Nepal) ......... .................................. L. buddhista Baroni Urbani

- Ventral margin of petiolar sternite with sub-circular projection. Subpetiolar process present as a small and hook like spine. PPI = 80–86; CI ≤ 74; PI = 117–124 ( China)........................................... ........ L. macauensis Leong, Yamane and Guénard

15) Petiole in dorsal view with sharp and protruding anterolateral corners, with well concave anterior margin........................................................ 16

- Petiole in dorsal view with blunt and non-protruding anterolateral corners, with slightly concave to convex anterior margin ................................ 17

16) Petiolar node almost twice as long as wide (PI = 60); post petiolar node almost as wide as long (PPI = 90); propodeal dorsum and declivity in lateral view meeting at an angular corner; masticatory margin of mandibles with a long and well-defined basal tooth ( Singapore) ........................................ .......................... L. hypodracos Wong & Guénard

- Petiolar node almost as long as wide (PI = 82–

100); post petiolar node distinctly wider than long (PPI = 133–137); propodeal dorsum and declivity in lateral view meeting at a rather rounded corner; masticatory margin of mandibles without a long and well-defined basal tooth ( Indonesia) ............. ..................................... L. clypeata Yamane & Ito

17) Anterior margin of clypeal disc almost touching the lower level of antennal insertion, with shallowly notched anterior lobe (Taiwan) .................. ......... L. taiwanensis Ogata, Terayama & Masuko

- Anterior margin of clypeal disc exceeding the lower level of antennal insertion with distinctly bilobed anterior lobe ........................................18

18) Posterior margin of head deeply concave in full-face view ................................................... 19

- Posterior margin of head almost straight in full-face view ..........................................................20

19) Petiolar node rectangular with slightly concave anterior margin in dorsal view; anterior distinctly shorter than posterior margin. Smaller species; HW: ca. 0.155 mm ( Japan) .................................. ................................... L. oceanica Baroni Urbani

- Petiolar node square with straight anterior margin in dorsal view; anterior margin as long as posterior margin. Larger species; HW: ca. 0.29 mm. ( India).................... L. lamellata Bharti & Kumar

20) Petiole sternite in lateral view distinctly protruding, with ventral margin bluntly angulate...... .......................................................................... 21

- Petiole sternite in lateral view indistinctly protruding, with ventral margin almost straight ( Thailand) .................................. L. thai Baroni Urbani

21) Anterolateral corners of petiole roundly convex in dorsal view HW: ca. 0.245 mm ( Singapore).... ................................................. L. havilandi Forel

- Anterolateral corners of petiole forming a small and sharp angle in dorsal view HW: ca. 0.280 mm ( India)................................................................... ................................................ L. escheri (Kutter)