Key to the Pheidole of North Vietnam

This worker key is based on: Eguchi, K. 2008. A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae). Zootaxa. 1902:1-118. [[Media:Eguchi 2008.pdf|PDF]]

The following key to species includes Pheidole indica which is widely distributed in East, Southeast and South Asia but has not yet been found in Northern Vietnam.

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 * Pheidole
 * Ants of Vietnam

1

 * Major & minor: apical 4 segments of antenna enlarged or just elongate. . . . . . 2


 * Major & minor: apical 3 segments of antenna enlarged or just elongate. . . . . . 3

2
return to couplet #1
 * Minor: petiole usually 0.85–1.0 times as long as postpetiole (excluding helcium); hairs on promesonotal dome rather dense . . . . . Pheidole gatesi


 * Minor: petiole usually less than 0.85 times as long as postpetiole (excluding helcium); hairs on promesontal dome rather sparse . . . . . Pheidole smythiesii

3
return to couplet #1
 * Major: hypostoma in the middle having an extremely developed median process, but nearly or completely lacking submedian processes; frontal carina well developed, partly overhanging antennal scrobe . . . . . Pheidole tjibodana


 * Major: hypostoma in the middle lacking any process, or having 2 processes (submedian processes only) or 3 processes (both median and submedian processes), but never dominated by a single stout median process; condition of frontal carina variable. . . . . . 4

4
return to couplet #3
 * Minor: frons and vertex punctured strongly and densely, and often overlain by weak reticulation . . . . . 5


 * Minor: frons and vertex smooth or only weakly sculptured (rugose, rugoso-punctate or rugoso-reticulate), but neither punctured strongly nor densely . . . . . 10

5
return to couplet #4
 * Minor: promesonotal dome with a conspicuous prominence or mound on its posterior slope. Major: dorsum of vertexal lobe bearing a few standing hairs among very short appressed background hairs . . . . . Pheidole capellinii


 * Minor: promesonotal dome at most with an inconspicuous mound on its posterior slope. Major: dorsum of vertexal lobe bearing many standing or subdecumbent hairs . . . . . 6

6
return to couplet #5
 * Major: frontal carina well developed, partly overhanging antennal scrobe . . . . . Pheidole colpigaleata


 * Major: frontal carina absent or inconspicuous (present just as rugulae) . . . . . 7

7
return to couplet #6
 * Minor: promesonotal spine reduced to a small dent . . . . . Pheidole foveolata


 * Minor: promesonotal spine moderately or well developed . . . . . 8

8
return to couplet #7
 * Minor: lateral face of promesonotal dome largely smooth and shining; mediodorsal part of the dome dimly punctured, smooth with several rugulae, or sometimes strongly rugoso-reticulate, but never punctured densely . . . . . Pheidole zoceana


 * Minor: dorsal and lateral faces of promesonotal dome entirely and densely punctured (the punctuation often overlain sparsely by weak rugulae). . . . . . 9

9
return to couplet #9
 * Minor: antennal scape exceeding posterior margin of head by less than the half length of antennal segment II, or not exceeding the posterior margin; maximal diameter of eye longer than antennal segment X . . . . . Pheidole parva


 * Minor: antennal scape exceeding posterior margin of head by the half length of antennal segment II or more; maximal diameter of eye as long as or shorter than antennal segment X . . . . . Pheidole rabo

10
return to couplet #4
 * Major: dorsum of vertexal lobe smooth and shining, or at most shagreened or very weakly rugoso-punctate . . . . . 11


 * Major: dorsum of vertexal lobe strongly sculptured: rugose, rugoso-reticulate or reticulate, often with enclosures/interspaces densely punctured . . . . . 15

11
return to couplet #10
 * Major: hypostoma in the middle at most with a pair of very small submedian processes (median process absent) . . . . . Pheidole megacephala


 * Major: hypostoma in the middle with conspicuous submedian processes and usually (but not always) a median process. . . . . . 12

12
return to couplet #11
 * Major: body very large (HW>2.00 mm) . . . . . Pheidole magna


 * Major: body small to medium (HW<2.00 mm). . . . . . 13

13
return to couplet #12
 * Major: petiole at most a little longer than postpetiole (excluding helcium); postpetiole relatively massive . . . . . Pheidole vieti


 * Major: petiole distinctly longer than postpetiole (excluding helcium); postpetiole not massive. . . . . . 14

14
return to couplet #13
 * Major: head relatively narrow (CI=91 or <91); promesonotal dome at most with an inconspicuous mound on its posterior slope . . . . . Pheidole vulgaris (in part - also )


 * Major: head relatively broad (CI>>91); promesonotal dome usually (but not always) with a low prominence or mound on its posterior slope . . . . . Pheidole fervida

15
return to couplet #10
 * Major: body very large (HW > 2.7 mm; FL > 2.1 mm) . . . . . Pheidole dugasi


 * Major: body small to large (HW < 2.3 mm; FL < 1.8 mm). . . . . . 16

16
return to couplet #15
 * Major: petiole with a large lobate subpetiolar process . . . . . Pheidole tumida


 * Major: petiole without a large lobate subpetiolar process (but often with a longitudinal carina or ridge ventrally) . . . . . 17

17
return to couplet #16
 * Major: postpetiole massive; petiole usually as long as or shorter than postpetiole (excluding helcium) . . . . . 18


 * Major: postpetiole not massive; petiole longer than postpetiole (excluding helcium). . . . . . 21

18
return to couplet #17
 * Major: frontal carina absent . . . . . Pheidole fortis


 * Major: frontal carina conspicuous . . . . . 19

19
return to couplet #18
 * Major: dorsum of head bearing sparse standing setae which are much longer and distinctly thicker than background hairs (many short deccumbent-suberect hairs) . . . . . Pheidole noda


 * Major: dorsum of head bearing sparse long standing hairs which are mostly indistinguishable from shorter and thinner background hairs. . . . . . 20

20
return to couplet #19
 * Minor: humeral area of promesonotal dome strongly rugose and often armed with a low humeral prominence . . . . . Pheidole rugithorax


 * Minor: humeral area of promesonotal dome neither strongly rugose nor armed with a humeral prominence . . . . . Pheidole laevithorax

21
return to couplet #17
 * Major: hypostoma with conspicuous submedian processes, and usually (but not always) with a conspicuous median process. . . . . . 22


 * Major: hypostoma at most with an inconspicuous median and inconspicuous submedian processes . . . . . 30

22
return to couplet #21
 * Minor: preoccipital carina conspicuous as a collar. Major: promesonotum in lateral view usually with a low to conspicuous prominence or mound on its posterior slope. . . . . . 23


 * Minor: dorsal part of preoccipital carina at most weakly present or completely absent. Major: promesonotum in lateral view at most with an inconspicuous prominence or mound on its posterior slope. . . . . . 25

23
return to couplet #22
 * Major: submedian processes of hypostoma well developed, much higher than median process (median process inconspicuous); vertexal lobes in full-face view relatively widely separated from each other . . . . . Pheidole indosinensis


 * Major: submedian processes of hypostoma moderately developed, at most a little higher than median process; vertexal lobes in full-face view relatively close to each other. . . . . . 24

24
return to couplet #23
 * Minor: the longest axis of eye having 8–9 ommatidia; head behind eyes in full-face view rather strongly produced posteriad . . . . . Pheidole elongicephala (in part - also )


 * Minor: the longest axis of eye having 6–7 ommatidia; head behind eyes in full-face view moderately produced posteriad . . . . . Pheidole ochracea (in part - also )

25
return to couplet #22
 * Major: head in lateral view rather strongly impressed on vertex; frontal carina rather conspicuous. . . . . . 26

inconspicuous or almost absent. . . . . . 28
 * Major: head in lateral view rather weakly or not impressed on vertex; frontal carina

26
return to couplet #25
 * Minor: propodeal spine reduced to a small dent . . . . . Pheidole pieli (in part - also )


 * Minor: propodeal spine distinctly larger than a small dent. . . . . . 27

27
return to couplet #26
 * Minor: dorsum of head from frons to vertex sparsely sculptured with weak longitudinal rugulae; posteriormost part of vertex and dorsolateral face of head weakly sculptured by rugulae, rugoso-reticulation and/or rugoso-punctation. Major: longitudinal rugulae on frons rather strong . . . . . Pheidole hongkongensis


 * Minor: head entirely smooth. Major: longitudinal rugulae on frons rather weak . . . . . Pheidole taipoana

28
return to couplet #25
 * Minor: propodeal spine reduced to a small dent; preoccipital carina in posterodorsal view absent or evanescent dorsally; the posterior slope of the promesonotal dome rather steep. . . . . . Pheidole pieli (in part - also )


 * Minor: propodeal spine distinctly larger than a small dent; preoccipital carina in posterodorsal view very weak but complete dorsally; the posterior slope of the promesonotal dome rather gentle. . . . . . 29

29
return to couplet #28
 * Major: vertex and dorsum of vertexal lobe covered with a weak or interrupted rugose or rugoso-reticulate sculpture which runs obliquely towards posterolateral corner of the lobes . . . . . Pheidole vulgaris (in part - also )


 * Major: vertex and dorsum of vertexal lobe sculptured with reticulation which never runs obliquely toward posterolateral corner of the lobe . . . . . Pheidole laevicolor

30
return to couplet #21
 * Major: first gastral tergite longitudinally rugose or densely rugoso-punctured over the entire surface, or excluding median portion of the posterior 1/3. . . . . . 31


 * Major: first gastral tergite smooth entirely, or weakly sculptured only in its anterior half. . . . . . 32

31
return to couplet #30
 * Major: frons densely sculptured with longitudinal rugulae; vertex in lateral view forming a gently sloping (and often weakly impressed) face toward vertexal lobe . . . . . Pheidole planifrons


 * Major: frons sparsely sculptured with longitudinally rugulae; vertex in lateral view strongly impressed in front of vertexal lobe . . . . . Pheidole yeensis

32
return to couplet #30
 * Major: vertexal lobes in full-face view narrowly separated from each other. . . . . . 33


 * Major: vertexal lobes in full-face view widely separated from each other. . . . . . 34

33
return to couplet #32
 * Minor: the longest axis of eye having 8–9 ommatidia; head behind eyes in full-face view rather strongly produced posteriad . . . . . Pheidole elongicephala (in part - also )


 * Minor: the longest axis of eye having 6–7 ommatidia; head behind eyes in full-face view moderately produced posteriad . . . . . Pheidole ochracea (in part - also )

34
return to couplet #32
 * Major: propodeal spine narrowly based and slightly curved apically. . . . . . 35


 * Major: propodeal spine broadly based and not curved apically. . . . . . 36

35
return to couplet #34
 * Major: posterior margin of head in full-face view shallowly concave. Minor: median part of clypeus smooth, without median longitudinal carina . . . . . Pheidole fervens


 * Major: posterior margin of head in full-face view deeply concave. Minor: median part of clypeus a zigzag or ramified (but rarely straight) median carina which is usually accompanied with weak rugulae . . . . . Pheidole plagiaria (in part - also )

36
return to couplet #34
 * Major: outer surface of foretibia bearing relatively long decumbent-suberect hairs . . . . . Pheidole plagiaria (in part - also )


 * Major: outer surface of foretibia bearing short decumbent-appressed hairs . . . . . Pheidole indica