Key to Pheidole minors of Borneo

This worker key is based on: Eguchi, K. 2001a. A revision of the Bornean species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae). Tropics Monograph Series. 2:1-154.

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1

• Antenna with 3-segmented club . . . . . 5

• Antenna with 5-segmented club, or without conspicuous club . . . . . 2

2

return to couplet #1

• Apical five antennal segments distinctly elongate, and forming conspicuous club; posterior part of head never forming elongate neck . . . . . 3

• Antenna lacking conspicuous club; posterior part of head forming extremely elongate neck . . . . . 4

3

return to couplet #2

• Promesonotal dome relatively high; metanotal groove in profile indistinct; in profile posterior declivity of promesonotal dome and dorsum of propodeum bearing ca. 10 standing hairs in total . . . . . Pheidole quinata

minor

• Promesonotal dome relatively low; metanotal groove in profile distinct; in profile posterior declivity of promesonotal dome and dorsum of propodeum bearing more than 20 standing hairs in total . . . . . Pheidole sabahna

minor

4

return to couplet #2

• Propodeal spine more than 4 times as long as diameter of propodeal spiracle; body light brown to brown . . . . . Pheidole montana

• Propodeal spine 2-2.5 times as long as diameter of propodeal spiracle; body brown to dark brown . . . . . Pheidole comata or Pheidole singaporensis

Pheidole comata

Pheidole comata minor

Pheidole singaporensis

Pheidole singaporensis minor

5

return to couplet #1

• Promesonotum armed with a pair of long and pointed spines . . . . . 6

• Promesonotum unarmed, or armed with a pair of processes, but the processes never developed into long and pointed spines (the processes of Pheidole aristotelis well developed but truncate or blunt apically) . . . . . 10

6

return to couplet #5

• Propodeal spine elongate-triangular, ca. 1.5 times as long as diameter of propodeal spiracle; head smooth and shining . . . . . Pheidole quadricuspis

minor

• Propodeal spine horn-like, more than 4 times as long as diameter of propodeal spiracle; head usually sculptured at least partly (in Pheidole acantha head sometimes almost smooth and shining) . . . . . 7

7

return to couplet #6

• Petiolar node in profile acute at apex; dorsum of alitrunk in profile bearing less than 10 standing hairs . . . . . Pheidole acantha

minor

• Petiolar node in profile blunt at apex; dorsum of alitrunk in profile usually bearing more than 20 standing hairs . . . . . 8

8

return to couplet #7

• Head punctured, or largely smooth and shining and partly punctured . . . . . Pheidole spinicornis

minor

• Head strongly reticulate . . . . . 9

9

return to couplet #8

• Body smaller (AL 1.00-1.20 mm); propodeal spine usually directed upward . . . . . Pheidole quadrensis

minor

• Body larger (AL 1.74-1.83 mm); propodeal spine usually directed posterodorsally . . . . . Pheidole lokitae

minor

10

return to couplet #5

• Legs from apex of femur to apex of tersus ivory-white contrasted with the remainder of femur which is dark brown . . . . . Pheidole fantasia

minor

• Legs almost unicolored . . . . . 11

11

return to couplet #10

• Eye consisting of 5-6 ommatidia . . . . . Pheidole parvicorpus

minor

• Eye consisting of more than 10 ommatidia . . . . . 12

12

return to couplet #11

• Head at least above subocular level distinctly sculptured; occipital carina weak or absent

dorsally on head; posterior declivity of promesonotal dome always without a distinct prominence . . . . . 13

• Head not, or only weakly, sculptured; occipital carina variable in condition; posterior declivity of promesonotal dome with, or without, a prominence . . . . . 23

13

return to couplet #12

• Dorsum of head punctured; ventrolateral face of head below subocular level smooth and shining in at least its anterior half . . . . . 14

• Dorsum of head punctured or reticulate; ventrolateral face of head below subocular level entirely punctured or reticulate; when venter of head less-sculptured (in P. retivertex and P. gombakensis), dorsum of head not punctured but largely rugoso-reticulate . . . . . 16

14

return to couplet #13

• In profile head below subocular level punctured and dull in its posterior half; petiolar node higher; eye broader . . . . . Pheidole parva

minor

• In profile head below subocular level entirely smooth and shining; petiolar node lower; eye narrower . . . . . 15

15

return to couplet #14

• Body brown . . . . . Pheidole rugifera

minor

• Body dark brown to blackish brown . . . . . Pheidole tenebricosa

minor

16

return to couplet #13

• Both head and alitrunk reticulate; propodeal spine ca. 6 times as long as diameter of propodeal spiracle . . . . . Pheidole sayapensis

minor

• At least mesopleuron and lateral face of propodeum punctured; propodeal spine usually less than 4.5 times as long as diameter of propodeal spiracle . . . . . 17

17

return to couplet #16

• Promesonotum with a pair of well-developed spines with blunt apices . . . . . Pheidole aristotelis

minor

• Promesonotum unarmed, or only with a pair of low tubercles which never develop into distinct spines . . . . . 18

18

return to couplet #17

• Median part of clypeus distinctly punctured and dull . . . . . 19

• Median part of clypeus smooth and shining . . . . . 20

19

return to couplet #18

• Posterior declivity of promesonotal dome relatively steep; propodeal spine longer than that of P. rabo . . . . . Pheidole tjibodana

minor

• Posterior declivity of promesonotal dome relatively gentle; propodeal spine shorter than that of P. tjibodana . . . . . Pheidole rabo

minor

20

return to couplet #18

• Promesonotum without a pair of tubercles; propodeal spine triangular or elongate-triangular, at most twice as long as diameter of propodeal spiracle . . . . . 21

• Promesonotum with a pair of low tubercles; propodeal spine horn-like, at least 3 times as long as diameter of propodeal spiracle . . . . . 22

21

return to couplet #20

• Promesonotum smooth and shining . . . . . Pheidole gombakensis

• Lateral part of promesonotum weakly punctured . . . . . Pheidole retivertex

minor

22

return to couplet #20

• Ventrolateral face of head below subocular level punctured . . . . . Pheidole angulicollis

minor

• Ventrolateral face of head below subocular level reticulate . . . . . Pheidole poringensis

minor

23

return to couplet #12

• Propodeal spine extremely long, extending over petiole . . . . . Pheidole modiglianii

minor

• Propodeal spine sometimes long, but never extending over petiolar node . . . . . 24

24

return to couplet #23

• Alitrunk completely lacking standing hairs . . . . . Pheidole huberi

minor

• Alitrunk bearing standing hairs . . . . . 25

25

return to couplet #24

• Declivitous face of promesonotal dome without any distinct prominence . . . . . 26

• Declivitous face of promesonotal dome with a prominence . . . . . 39

26

return to couplet #25

• Petiolar node very high; mesopleuron divided into two parts, of which lower part is more or less margined dorsally . . . . . 27

• Petiolar node not so high; mesopleuron usually not divided into upper and lower parts; if it is divided into two parts, the lower part is usually not margined dorsally . . . . . 28

27

return to couplet #26

• Longest axis of eye having 4 ommatidia; body yellowish brown . . . . . Pheidole sarawakana

minor

• Longest axis of eye having at least 5 ommatidia; body yellowish brown to dark brown . . . . . Pheidole sauberi or Pheidole elisae

minor

minor

28

return to couplet #26

• Occipital carina complete . . . . . 29

• Occipital carina almost evanescent, or absent dorsally on head . . . . . 36

29

return to couplet #28

• Distance between mandibular insertion and anterior margin of eye 1.5-1.6 times as long as maximal diameter of eye . . . . . Pheidole havilandi

minor

• Distance between mandibular insertion and anterior margin of eye at most 1.1 times as long as maximal diameter of eye . . . . . 30

30

return to couplet #28

• Metanotal groove in profile being a deep emargination . . . . . Pheidole tawauensis

minor

• Metanotal groove shallow or indistinct . . . . . 31

31

return to couplet #30

• Petiole more than 1.7 times as long as postpetiole; anterior declivity of promesonotal dome in profile relatively steep . . . . . Pheidole lucioccipitalis

minor

• Petiole at most 1.5 times as long as postpetiole; anterior declivity of promesonotal dome in profile relatively gentle . . . . . 32

32

return to couplet #31

• Several conspicuous rugulae running immediately above eye . . . . . Pheidole submonticola

minor

• No conspicuous rugulae running immediately above eye . . . . . 33

33

return to couplet #32

• Upper part of mesopleuron, and lateral face of propodeum largely smooth and shining . . . . . 34

• Mesopleuron and lateral face of propodeum punctured . . . . . 35

34

return to couplet #33

• Eye small, with ca. 5 ommatidia on longest axis; head in full-face view oval . . . . . Pheidole upeneci

minor

• Eye large, with ca. 10 ommatidia on longest axis; head in full-face view subrectangular . . . . . Pheidole manukana

minor

35

return to couplet #33

• Body yellowish brown; promesonotum with a pair of very low tubercles dorsolaterally . . . . . Pheidole kikutai

minor

• Body brown; promesonotum without tubercles . . . . . Pheidole megacephala

minor

36

return to couplet #28

• Propodeal spine 3.5-4 times as long as diameter of propodeal spiracle . . . . . Pheidole deltea

minor

• Propodeal spine at most twice as long as diameter of propodeal spiracle . . . . . 37

37

return to couplet #36

• In profile promesonotum convex, with steep posterior declivity . . . . . Pheidole hortensis or Pheidole clypeocornis

Pheidole hortensis minor

Pheidole clypeocornis minor

• In profile promesonotum evenly convex, or flat and low . . . . . 38

38

return to couplet #37

• Promesonotal dome in profile lower, and flatter dorsally; CI 89-95 . . . . . Pheidole merimbun or Pheidole planidorsum

Pheidole merimbun minor

Pheidole planidorsum minor

• Promesonotal dome in profile higher, and convexer dorsally; CI 84-89 . . . . . Pheidole butteli

minor

39

return to couplet #25

• Promesonotum with a pair of low tubercles . . . . . 40

• Promesonotum without a pair of tubercles . . . . . 41

40

return to couplet #39

• Distance between mandibular insertion and anterior margin of eye 1.3-1.5 times as long as maximal diameter of eye; postpetiole 2.3-2.5 times as broad as petiolar node; anterior declivity of promesonotal dome relatively steep; lateral face of promesonotum weakly punctured . . . . . Pheidole ghigii

minor

• Distance between mandibular insertion and anterior margin of eye 0.9-1.0 times as long as maximal diameter of eye; postpetiole 2.0-2.2 times as broad as petiolar node; anterior declivity of promesonotal dome relatively gentle; lateral face of promesonotum smooth and shining . . . . . Pheidole plinii

minor

41

return to couplet #39

• Prominence on posterior declivity of promesonotal dome, and dorsum of propodeum each bearing a pair of standing hairs . . . . . Pheidole cariniceps

minor

• Prominence on posterior declivity of promesonotal dome, and dorsum of propodeum each bearing more than one pair of standing hairs . . . . . 42

42

return to couplet #41

• Occipital carina forming a well-developed flange, which is in full-face view narrowed at its base . . . . . Pheidole aglae

minor

• Occipital carina sometimes forming a flange, but in full-face view not narrowed at base . . . . . 43

43

return to couplet #42

• Clypeus weakly and irregularly rugose and weakly shining . . . . . Pheidole plagiaria

minor

• Clypeus smooth and shining . . . . . 44

44

return to couplet #43

• Large part of dorsum of head very weakly punctured; promesonotal dome in profile higher and rounder . . . . . Pheidole inornata

minor

• Dorsum of head except the area around antennal insertion smooth over the surface; promesonotal dome in profile lower . . . . . 45

45

return to couplet #44

• Lower part of mesopleuron smooth and shining, or slightly punctured; petiole 0.9-1.0 times as long as postpetiole . . . . . Pheidole annexa

minor

• Mesopleuron punctured; petiole at least 1.3 times as long as postpetiole . . . . . 46

46

return to couplet #45

• Head broader (CI 82-87) . . . . . Pheidole fervens

minor

• Head narrower (CI 78-81) . . . . . Pheidole jacobsoni

minor