Comprehensive Description

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The Genus ODONTOMACHUS Latreille

List of the Melanesian and Moluccan Odontomachus , Arranged in Species Groups and Including New Synonymy.

Group of 0. saevissimus Fr. Smith angulatus Mayr

animosus Fr. Smith

emeryi Mann

gressitti Wilson

imperator Emery

latissimus Viehmeyer

linae Donisthorpe

malignus Fr. Smith

= Odontomachus tuberculatus Roger

montanus Stitz

opaculus Viehmever

papuanus Emery

= Odontomachus papuanus var. concentrions Emery

rufithorax Emery

saevissimus Fr. Smith

= Odontomachus imperator var. tauerni Stitz

= Odontomachus transversostriatus Donisthorpe

Group of 0. simillimus Fr. Smith

aciculatus Fr. Smith

= Odontomachus ruficeps cephalotes var. verticillatus Stitz aeneus Emery cephalotes Fr. Smith

= Odontomachus ruficeps cephalotes var. cruenta Emery

= Odontomachus ruficeps cephalotes var. fusca Emery

= Odontomachus ruficeps cephalotes var. ternatensis Forel

= Odontomachus ruficeps cephalotes var. tamensis Stitz

= Odontomachus ruficeps subsp. aruanus Karawajew

= Odontomachus ruficeps cephalotes var. longitudinalis Donisthorpe

simillimus Fr. Smith ( haematoda auct. part.)

= Odontomachus haematodus var. fuscipennis Forel

Group of 0. tyrannicus Fr. Smith

nigriceps Fr. Smith

= Odontomachus angulatus subsp. praefectus Forel

testaceus Emery

= Odontomachus gulosus Emery

= Odontomachus gulosus var. nubila Emery

= Odontomachus nigrifrons Donisthorpe

tyrannicus Fr. Smith

= Odontomachus tyrannicus var. obsolescens Donisthorpe

Key to the Odontomachus Species of Melanesia and the Moluccas, based on the Worker Caste 1

1. Extraocular furrow not demarcated posteriorly, the posterior declivity of the ridge sloping evenly and without a break into the occipital zone (see Fig. 3, upper); exceptionally slender species, with heads either entirely blackish brown or else bearing a distinct infuscation in the frontal area, thus contrasting with a predominantly yellow or light reddish brown gaster ( tyrannicus group) ................ 2

Extraocular furrow demarcated posteriorly by a distinct secondary rise between it and the occipital zone (see Fig. 3, lower); stouter species, never showing the above color combination ..............4

2. Entire head, alitrunk, and petiole blackish brown, contrasting sharply with the gaster, which is light reddish brown .................... tyrannicus Fr. Smith

i Two morphological terms pertaining to the head and used in the key and subsequent descriptions need definition. The ocular ridge is the transverse welt hearing the eye; the two ocular ridges arise at the anterior margins of the compound eyes and converge obliquely and posteriorly toward the midline of the head (see Fig. 3). The extraocular furrow is the trench-like depression just posterior to the ocular ridge in species or the saevissimus and simillimus groups; this term is not used to refer to any finer sculptural details such as rugae or striae. The standardized measurements used have already been defined in an earlier paper (Bull. Mus. Comp. Zool., 116:355, 1957).

Body of a different color 3

3. Entire head blackish brown; the remainder of the body testaceous, with local infuses tions on the gaster nigricepx Fr. Smith

At most only the central portion of the head dark in color, and this area ranges from light brown to blackish brown; the remainder of the body testaceous, with local infuscations on the gaster testaceus Fr. Smith

4. Central portion (disc) of first gastric tergite striate 5

Entire first gastric tergite completely smooth or partly shagreened 7

5. Much of body surface showing pronounced metallic reflections aeneus Emery

Body surface completely lacking metallic reflections 6

6. Sculpturing of first gastric tergite in addition to central striae consisting chiefly of either coarse shagreening or striation; if the latter, then the individual striae are strongly curved and many run longitudinally for variable distances cephalotes Fr. Smith

Sculpturing of first gastric tergite consisting of striae that are at most slightly curved and always transverse aciculatus Fr. Smith

7. Most of the pronotum, including all of its dorsal surface exclusive of the anterior “neck,” completely lacking striae, its surface either shagreened or smooth and shining .......................... 8

Most or all of the pronotum covered by striae; in occasional specimens a limited transverse strip may lack striae and be smooth and shining, but in these individuals the greater part of the pronotum is still striate ......................................12

8. Occiput bearing distinct tumosities on either side of the median line of the head one-third the distance from the median line to the occipital corners; color uniformly yellowish orange malignus Fr. Smith

Occiput lacking tumosities; color other than described above 9

9. Posterior border of basal portion of petiolar spine viewed exactly from the side strongly convex, contrasting markedly with the weakly convex anterior border (Fiji Islands) angulatus Mayr

Posterior border of basal portion of petiolar spine viewed exactly from the side only weakly convex, appearing very similar in this respect to the anterior border (New Guinea) ......................10

10. Seen exactly from the side, the anterior face of the petiolar node forms an angle of 120°-130° with the dorsal node face (for a similar condition, see drawing of papuanus in Fig. 1) .... latissimus Viehmeyei Seen exactly from the side, the anterior face of the petiolar node forms an angle of approximately 100° with the dorsal node face (see drawing of impcrator in Fig. 1) .................................11

11. Extraocular furrows at least partly striate; head and gaster black, alitrunk and petiole red ruflthorar Emery

Extraocular furrows completely lacking striae; body uniformly dark reddish brown ................................ imperator Emery

12. Striae covering almost the entire dorsum of the head ............13

Striae covering at most the interocular depression and parts of the ocular ridge and extraocular furrow, and strongly developed only in the interocular depression ..................................15

13. Entire body concolorous blackish brown (widespread over all Melanesia and the Moluccas) .......................... simillimus Fr. Smith

Head, alitrunk, and petiole dull dark reddish yellow; gaster dark reddish brown (New Guinea only) .............................14

Fig. 1. Side views of petioles of worker syntypes of Odontomachus imperator Emery (A) and 0. papuanus Emery (B); based on specimens in the Emery Collection, Genoa.

14. Mesepisternum completely smooth and shining except for the anterior sixth of its length, which is vertically striate; smaller species, HW of unique type 2.08 mm (Manokwari, Neth. New Guinea) ....... animosus Fr. Smitli

Mesepisternum completely covered by dense vertical striae; larger species, HW of syntype examined 2.64 mm (Sepik Watershed, N-E. New Guinea) ................................... montanus Stitz

15. Extraocular furrows partly striate, although occasionally the striae arc very feeble and limited to the inner one-fifth of the furrows 16

Extraocular furrows completely smooth and shining ..............18

16 . Head, alitrunk, and petiole light reddish brown; gaster medium reddish brown ......................... linae Donisthorpe (partim)

Body concolorous dark to blackish brown 17

17. Striae limited to upper fifth of extraocular furrows; anterior and anterodorsal faces of petiolar node grading into one another through an even curve without any sign of an intervening angle papuanus Emery (partim)

Striae covering approximately the upper half of the extraocular furrow; anterior and anterodorsal petiolar node faces meeting in n distinct angle of about 100° ................. opaculusViehmeyer

18. Anterodorsal surface of petiole, exclusive of the spine, transversely striate; color of head and alitrunk yellowish to light reddish brown, with the possible exception of the mesonotum, which is occasionally (in gressitti ) medium to dark reddish brown 10

Either the anterodorsal surface of the petiole is completely smooth, or the color of the head and alitrunk is dark reddish brown, or both 20

19. Head, alitrunk, and petiole uniformly light reddish brown; larger species, HW of two specimens examined 2.52-2.54 mm linae Donisthorpe (partim)

Either head, mesonotum, and gaster dark reddish brown, contrasting with the yellowish brown alitrunk (exclusive of mesonotum) and petiole (Central Highlands of New Guinea), or body concolorous yellowish brown, the mesonotum a shade darker than the rest (Guadalcanal); smaller species, HW of two type specimens 2.16 mm gressitti Wilson

20. Posterior face of petiole, extending from the tip of the spine to the posterior peduncle, evenly concave when viewed from the side saevissimus Fr. Smith (partim)

Lower half of posterior face of petiole appearing distinctly convex when viewed from the side ................................. 21

21. Mesepisternum almost completely smooth; body and antennae dark reddish brown, legs yellowish brown (New Guinea) papuanns Emery

Mesepisternum completely striate; coloration not as above 22

22. Head and gaster dark reddish brown; alitrunk and petiole light yellowish red, with the mesonotum lightly infuscated (Solomon Islands) emeryi Mann

Gaster medium reddish brown, only slightly darker than the alitrunk (head color unknown) (New Ireland variant) saevissimus Fr. Smith (partim)


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