Key to Indomalayan Proceratium Species

The following key to workers is based on Baroni Urbani, C., de Andrade, M.L. (2003) The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie, 36, 1–492.

Proceratium williamsi occurs in this region but is not included in this key.

1

Petiole with peduncle, convex or subconvex in profile. Anterior clypeal border strongly protruding anteriorly or at least medially triangular. Mandibular base without light macula. First gastral tergite without a clear macula visible in transparency posteriorly. Palp formula 3,2 or 4,3 . . . . . 2

Petiole without peduncle, rectangular in profile. Anterior clypeal border straight or weakly concave, never protruding anteriorly. Base of the mandibles with a light macula. Palp formula 2,2. First gastral tergite with a light macula visible in transparency posteriorly . . . . . 6

2

return to couplet #1

Sides of the propodeum with a developed spine. Propodeal lobes with a broad lamellaceous tooth only . . . . . 3

Sides of the propodeum at most with a small tip, without a true spine. Propodeal lobes without broad lamellaceous tooth, at most with a lamella over the whole declivous face . . . . . 4

3

return to couplet #2

First gastral tergite angulate on the curvature. Gaster entirely foveolate. Malaysia (Sarawak) . . . . . Proceratium foveolatum

Head of Proceratium foveolatum worker

Profile of Proceratium foveolatum worker

First gastral tergite round on the curvature. Gaster at most punctate. Borneo, Brunei, Malaysia (Sabah and Sarawak), Thailand and Singapore . . . . . Proceratium deelemani

Head of Proceratium deelemani worker

Profile of Proceratium deelemani worker

4

return to couplet #2

Frontal carinae fused. Clypeus strongly protruding anteriorly. Mesosoma, petiole, postpetiole and gaster foveolate. Malaysia (Sabah) . . . . . Proceratium microsculptum

Head of Proceratium microsculptum worker

Profile of Proceratium microsculptum worker

Frontal carinae not touching each other. Clypeus reduced to a triangular tooth between the antenna1 sockets. Mesosoma, petiole and postpetiole granulate, gaster punctate . . . . . 5

5

return to couplet #4

Body without long erect hairs. Propodeal sides at most with a narrow lamella. Hairs on mesobasitarsi shorter than 1/2 the mesobasitarsal length. Bhutan . . . . . Proceratium bhutanense

Head of Proceratium bhutanense worker

Profile of Proceratium bhutanense worker

Body with long erect hairs. Propodeal sides with a broad lamella over their whole length. Mesobasitarsi with hairs 1/2 the mesobasitarsal length. Malaysia (Pahang) . . . . . Proceratium malesianum

Head of Proceratium malesianum worker

Profile of Proceratium malesianum worker

6

return to couplet #1

Postpetiole in dorsal view concave and laterally lobate. Posterior border of first gastral tergite folded. Head, mesosoma, petiole, postpetiole and gaster strongly sculptured. First gastral tergite with traces of longitudinal rugosities . . . . . 7

Postpetiole in dorsal view neither concave nor laterally lobate. Posterior border of first gastral tergite not folded. Head, mesosoma, petiole, postpetiole and gaster less strongly sculptured. First gastral tergite without traces of longitudinal rugosities . . . . . 8

7

return to couplet #6

Frontal area at least 1/3 of the head width. Sides of the propodeum with a small denticle. Rugosities on the first gastral tergite more irregular and thin (Fig. 146). SI < 65. Malaysia (Sarawak) . . . . . Proceratium angulinode

Head of Proceratium angulinode worker

Profile of Proceratium angulinode worker

Frontal area about 1/4 of the head width. Sides of the propodeum with a broad lamellaceous tooth. Rugosities on the first gastral tergite more regular and thicker (Fig. 147). SI >74. Malaysia (Sarawak) . . . . . Proceratium striativenter

8

return to couplet #6

TL<2.65 mm. HbaL ≤ 0.24 mm. Papua New Guinea, Philippines, Sumatra, Malaysia, Sabah and Solomon Islands . . . . . Proceratium papuanum

Head of Proceratium papuanum worker

Profile of Proceratium papuanum worker

TL ≥ 2.72 mm. HbaL > 0.27 mm . . . . . 9

9

return to couplet #8

Hairs on the mid basitarsi never longer than ½ of the basitarsal length . . . . . 10

Hairs on the mid basitarsi 2/3 of the basitarsal length . . . . . 12

10

return to couplet #9

Mesosoma, petiole and postpetiole smooth or at most minutely punctate. SI > 69. Malaysia (Pahang) . . . . . Proceratium terraealtae

Head of Proceratium terraealtae worker

Profile of Proceratium terraealtae worker

Mesosoma, petiole and postpetiole densely granulopunctate. SI < 67 . . . . . 11

11

return to couplet #10

Frontal area narrow and frontal carinae short (Fig. 129). Colour dark ferruginous. Malaysia (Sarawak) . . . . . Proceratium dayak

Head of Proceratium dayak worker

Profile of Proceratium dayak worker

Frontal area broader and frontal carinae longer (Fig. 143). Colour yellowish to brown. Japan, Taiwan . . . . . Proceratium japonicum

Head of Proceratium japonicum worker

Profile of Proceratium japonicum worker

12

return to couplet #9

Frontal area narrow, about ¼ of the maximum HW. CI < 92. SI > 68. Colour light brown. Thailand . . . . . Proceratium siamense

Head of Proceratium siamense worker

Profile of Proceratium siamense worker

Frontal area broad, about 1/3 of the maximum HW. CI > 93. SI < 67. Colour ferruginous . . . . . 13

13

return to couplet #12

Hairs of hind basitarsi at most ½ of the basitarsal length. CI > 98. Malaysia (Sarawak) . . . . . Proceratium sulawense

Head of Proceratium sulawense worker

Profile of Proceratium sulawense worker

Hairs of hind basitarsi longer than ½ of the basitarsal length. CI < 97 . . . . . 14

14

return to couplet #13

IGR 0.44. First gastral tergite convex (Fig. 148). Malaysia (Sabah) . . . . . Proceratium banjaranense

Head of Proceratium banjaranense worker

Profile of Proceratium banjaranense worker

IGR ≥ 0.48. First gastral tergite less convex (Fig. 149). Malaysia (Sabah) . . . . . Proceratium dusun

Head of Proceratium dusun worker

Profile of Proceratium dusun worker