G. C. Wheeler and J. Wheeler.
The Ant Larvae of the Myrmicin Tribe Pheidologetini.
Psyche 60:129-147, 1953.

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PSYCHE
Vol. 60 December, 1953 No. 4
THE ANT LARVAE OF THE MYRMICINE TRIBE
BY GEORGE C. WHEELER and JEANETTE WHEELER Department of Biology, University of North Dakota In the Genera Znsectorum Emery included the genera Lophomyrmex, Trigonogaster, Pheidologeton, Aneleus, Oli- gomyrmex, Evrebomyrma, Carebara and Paedalgus in the tribe Pheidologetini. Wheeler placed these genera in the Solenopsidini but admitted (1922, p. 659) that the latter tribe was "very unsatisfactorily defined." We have followed Emery.
The tribe Pheidologetini comprises about a hundred species, most of which are Paleotropical. The tribe is noted for the large size of the queens. In C. vidva, for example, the volume ratio of queen to worker is several thousand to one. Pheidologeton is a genus of harvesters, with a poly- morphic worker caste ranging' from minute m,inimae through a graded series to gigantic soldiers with enormous heads. The other genera are suspected of having relations with termites, though just what sort of relations has never been proved.
At least they nest in termitaria. Aneleus and Oligomymex have the worker caste strongly dimorphic - large headed soldier and small worker. In Lophomyrmex, Trigonogaster, Erebomyrma,, Carebara and Paedalgus the worker caste is monomorphic and minute.
In this article we have described the larvae of 13 species in seven genera.
These larvae do not constitute a
homogeneous group. They are nevertheless better defined 'The research on which this article is based was aided by a grant-in-aid from the Sigma Xi - Resa Research Fund.




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130 Psyche [December
as a group than are the larvae of the Solenopsidini (either in the sense of Emery or in the sense of Wheeler) to the ex- tent that at least a few minor characters are common to all the known genera. The subtribes, however, are homo- geneous and easily differentiated. Within each subtribe the genera are not easily distinguished.
Tribe PHEIDOLOGETINI Emery
Body hairs moderately numerous and uniformly dis- tributed. Anchor-tipped hairs absent. Antennae small. Head hairs few. Labrum short and broad (breadth 2x to 3x length). Ratio of head width to mandible length = 3.0 to 4.0 ; average 3.5. Ratio of mandible length to mandible width (at base) = 1.4 to 2.4; average 1.7. Surface of maxil-
lae without spinules. Anterior surface of labium spinulose. Subtribe LOPHOMYRMICINI Emery
Body hairs all of the same shape: either with the tip denticulate or with the tip bifid. Labrum trilobed, the median lobe projecting posteriorly. posterior surface of labrum densely spinulose. Mandibles as a whole curved medially ; teeth surrounding a denticulate area ; anterior surface spinulose. Labium with a median anteroventral projection, which bears the opening of the sericteries at its apex. Labial palp a low knob bearing five sensilla. Hypo- pharynx spinulose.
Genus Lophomyrmex Emery
Thorax rather stout and bent ventrally at right angles; abdomen elongate-ovoidal ; diameter greatest at the fourth and fifth abdominal somites; posterior end broadly rounded. Body hairs moderately numerous and short; all with the tip denticulate. Antennae small. Head hairs few, short to moderately long, with the tip denticulate. Labrum small, trilobed, with the median lobe projecting posteriorly; pos- terior surface densely spinulose. Mandibles slender and thin ; curved medially ; apical tooth curved medially and posteriorly ; a large anterior subapical tooth directed antero- ventrally; a large blunt medial tooth directed postero- ventrally ; teeth surrounding a denticulate area ; anterior surface with several sharp spinules. Maxillary palp a peg



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19531 Wheeler and Wheeler - Myrrnicine Larvae 131 bearing five sensilla. Labium with a median anteroventral spinulose projection, with the opening of the sericteries at its apex. Labial palp a low knob bearing five sensilla. Hypopharynx with a
few oblique rows of minute spinules.
Text figure 1. Trigonogaster recurvispinosa kemneri Wheeler, A-F -A, head in anterior view, X85; B, left mandible in medial view, X247; C, left mandible in anterior view, X247; D, body hair, X329; E, larva in side view, Xl8; F, left half of labrum and labium in sagittal view, X165. Erebomyrma sp., G-I -G, head in anterior view (with hair bases only), X108; H, left mandible in anterior view, X247; I, profile, X18. Lophomyrmex qwdrispinosus (Jerdon), J-N -J, head in anterior view, X85; K, left mandible in anterior view, X192; L, left mandible in medial view, X192; M and N, two body hairs, X209. Lophomyrmex qdrispinosus (Jerd,on)
(Text. fig. 1, J-N)
Thorax rather stout and bent ventrally at right angles; abdomen elongate-ovoidal; diameter greatest at the fourth



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132 Psyche i~~cembtr
and fifth abdominal somites ; posterior end broadly rounded, anterior end formed from the dorsum of the prothorax. Anus posteroventral, Leg vestiges present. Segmentation indistinct Integument of ventral surface of thorax and abdominal somites MII with numerous transverse rows of spinules. Body hairs moderately numerous, short (0.036- 0.126 mm), all with denticulate tip; hairs without alveo- lus and articular membrane except on the prothorax. Head moderately large ; cranium transversely subelliptical, breadth 1.25~ length. Antennae small, each with three (rarely two) sensilla, each of which bears a spinule. Head hairs few, short to moderately long (0.018-0.072 mm), with denticulate tip, Labrum small, short (width 2X lenj?th), trilobed, the median lobe projecting posteriorly; anterior surface of each lateral lobe with three minute hairs and/or sensilla; ventral border of each lateral lobe with three sen- silla and several short oblique rows of exceedingly minute spinules; posterior surface of each half with 1-2 isolated and a cluster of 3-4 sensilla; posterior surface spinulose, the spinules minute and in numerous Ions transverse rows. Mandibles slender and thin; curved medially; apical tooth curved medially and posteriorly; a large anterior subapical tooth directed anteroventrally; a large blunt medial tooth directed posteroventrally ; teeth surrounding a denticulate area; anterior surface with several sharp spinules. Maxil- lae with the apex paraboloidal; palp a peg with one sub- apical (bearing a spinule) and four apical sensilla; galea a rather tall peg with two apical sensilla. Labinm with a median anteroventral projection covered with short rows of minute spinules; palp a low knob with five sendla (one of which bears a spinule) ; a minute amsillurn between each palp and the opening of the sericteries; the latter a transverse slit on the end of the projection. Hypopharynx with a few oblique rows of minute spinules. SEXUAL LARVA : Elongate-ovoKlal; head small, on the ven- tral surface near the anterior end. Body naked. Head naked hut with minute aenailIa. Mandibles with all teeth directed medially. Otherwise similar to worker larva. Material studied : numerous slightly damaged larvae from Java labelled "var. opa,dceps Viehmeyer."



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1Μφ53 Wheeler and Wheeler - Myrwkhe Larvae 133 Genus TRIGONOGASTER Forel
Long, slender, club-shaped, with only the prothorax bent ventrally to form a very short neck; posterior end broadly round. Body hairs moderately numerous, very short, usual- ly with a short-bifid tip. Antennae minute. Head hairs few, long and with some part of the distal half finely den- ticulate. Labrum trilobed, with the median lobe projecting posteriorly ; posterior surface densely spinulose. Mandibles
curved medially; apical tooth round-pointed and curved medially; a large anterior subapical tooth directed antero- ventrally ; a large blunt medial tooth directed posteroven- trally and sometimes covered with spinules; teeth surround- ing a denticulate area; anterior surface with many long slender spinules arranged in transverse arcuate rows. Maxillary palp a peg bearing five sensilla. Labium with
a median anteroventral spinulose projection, with the open- ing of the sericteries at its apex; labial palp a low knob bearing five sensilla. Hypopharynx with numerous trans- verse rows of minute spinules.
Trigonogaster recurvispinosa kemneri Wheeler (Text fig. 1, A-F)
Long, slender, club-shaped, with only the prothorax bent ventrally to form a very short neck; posterior end broadly rounded. Anus posteroventral. Spiracles small, the meso- thoracic larger than the others. Integument with minute spinules on the ventral surface of the thorax. Body hairs moderately numerous, uniformly distributed, very short (0.018-0.108 mm), usually with very short-bifid tip ; with alveolus and articular membrane. Head moderately large ; cranium transversely subelliptical, slightly broader than long. Antennae minute, each with three sensilla, each of which bears a spinule. Head hairs few, long (0.04-0.105 mm) and with some part of the distal half finely denticulate. Labrum short (breadth 2x length), trilobed, the median lobe projecting posteriorly ; anterior surface of each lateral lobe with 2-3 minute hairs and/or sensilla ; ventral border of each lateral lobe spinulose and with one isolated and two contiguous sensilla ; posterior surf ace of each half with 3-4 isolated and two contiguous sensilla ; posterior surface densely spinulose, the spinules minute and in numerous



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134 Psyche [December
long transverse rows. Mandibles curved medially ; apical tooth round-pointed and curved medially; a large anterior subapical tooth directed anteroventrally ; a large blunt medial tooth directed posteroventrally and sometimes covered with spinules; teeth surrounding a denticulate area; anterior surface with many long slender spinules arranged in transverse arcuate rows. Maxillae with the apex paraboloidal; palp a peg with one subapical (bearing a spinule) and four apical (two bearing each a short spinule) sensilla; galea a tall slender frustum with two apical sensilla. Labium with a median anteroventral pro- jection covered with short rows of minute spinules; palp a low knob with five sensilla (three bearing a spinule each) ; opening of sericteries a short transverse slit on the end of the projection. Hypopharynx with numerous transverse rows of minute spinules. (Material studied: eight larvae from Java.)
Subtribe PHEIDOLOGETINI Emery
Body hairs of two or three types; those on the dorsal and lateral surfaces deeply bifid, with the branches curling away from each other. Labrum subrectangular, with the ventral corners rounded. Posterior surface of labrum sparsely spinulose or without spinules. Mandibles as a whole not curved medially; the teeth not surrounding a denticulate area ; anterior surface without spinules. Labi- um without a median projection. Labial palp represented by a cluster of four sensilla. Hypopharynx apparently with- out spinules.
Genus Pheidologeton Mayr
Short and stout; prothorax forming a stout neck, which is bent ventrally to a right angle; dorsal profile C-shaped, ventral profile of abdomen nearly straight; diameter great- est at abdominal somites 111 and IV. Body hairs moderately numerous and short. Of three types (with intergrades) : (1) deeply bifid, with the branches curling away from each other and enlarged at the tip, the most abundant type (but absent from the ventral surface) ; (2) bifid, with the branches acuminate and nearly straight, a few on the ven- trolateral surfaces; (3) a few simple hairs on the ventral



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19531 tVheeIer and Wheeler - Myrmicine Larvae 135 surface. Antennae small. Head hairs few, short, simple or with denticulate tip. Labrum subrectangular; posterior surface sparsely spinulose. Mandibles small, short, stout and thick; apex forming a small tooth which is curved medially and posteriorly; with two small medial teeth near the anterior surface. Maxillary palp a low elevation bear- ing four sensilla ; galea a low knob. Labial palp represented by a cluster of four sensilla. Sexual ( ?) larva voluminous, plump, turgid, bean-shaped; head exceedingly minute, on the ventral surface near the anterior end; mandibles with the apical tooth vestigial and with only one medial tooth. Pheidologeton diversus (Jerdon)
(PI. 6, figs. 8-16)
MATURE WORKER LARVA: Length about 2.1 mm. Short and stout; prothorax forming a stout neck, which is bent ventrally to a right angle; dorsal profile C-shaped, ventral profile of abdomen nearly straight; diameter greatest at abdominal somites 111 and IV. Anus ventral. Leg vestiges present. Segmentation indistinct. Mesothoracic spiracle a third larger than the metathoracic, the others diminishing slightly toward the posterior end. Integument of dorsal surface of posterior somites sparsely spinulose, the spinules minute and Isolated or in very short rows; on the ventral surface of the thorax and abdominal somites I and 11 they are in longer rows. Bmody hairs moderately numerous and short. Of three types: (1) deeply bifid, about 0.054 mm, with the branches curling away from each other and en- larged at the tip, the most abundant type, absent from the ventral surface; (2) bifid, 0.024-0.054 mm, with the branches acuminate and nearly straight, a few on the ventrolateral surfaces; (3) simple, about 0.024 mm, a few on the ventral surface; there are intergrades between the several types; a few hairs on the ventral surface have alveolus and articular membrane. Head large ; cranium suboctagonal, but with the angles rounded, slightly broader than long. Antennae small, each with three (rarely four) sensilla each bearing a spinule. Head hairs few, short (0.006-0.036 mm), simple or with the tip denticulate. Lab- rum short and broad (breadth 3X length) ; subrectangular, with the ventral corners rounded; each half of anterior



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136 Psyche [December
surface with 5-6 sensilla ; ventral border with a few spinules and two isolated sensilla; posterior surface with 5-6 sen- silla and three spinulose areas, a central area of minute spinules arranged in a few scattered short rows and two ventrolateral areas of coarse isolated spinules. Mandibles
small, short, stout and thick; apex forming a small tooth which is curved medially and posteriorly; with two small medial teeth near the anterior surface. Maxillae with the apex paraboloidal ; palp a low elevation bearing four sen- silla; galea a low knob bearing two sensilla. Anterior sur-
face of labium sparsely spinulose, the spinules isolated or in short transverse rows; palp represented by a cluster of four sensilla; an isolated sensillum between each palp and the opening of the sericteries ; the latter a short transverse slit.
YOUNG LARVA: Length about 1.1 mm. Th!orax bent ven- trally to an acute angle; diameter nearly uniform but greatest at the third and fourth abdominal somites. Head
relatively very large.
Posterior end forming a knob which
is directed posteroventrally.
Otherwise as in the mature
larva.
Material studied: two dozen larvae from the Philippine Islands.
Oligomyrmex parvicornis Forel, Figs. 1-7 -1, head in anterior view, Xl15; 2, left mandible in anterior view, X303; 3 and 4, two body hairs, X418; 5, first instar larva in side view, X39; 6, young larva in side view, X39; 7, mature larva in side view, X39. Pheidologeton diversus (Jerdon), Figs. 8-16 -8, head in anterior view, X77; 9, left mandible in anterior view, X209; 10, left mandible in medial view, X209;
11, young larva in side view, X36; 12, mature larva in side view, X36; 13-16, four body hairs, X418. Pheidologeton affhzis
(Jerdon), Figs. 17 and 18 -17, profile of sexual (?) larva, X2.7; 18, left mandible of sexual (?) larva in anterior view, X209. Carebara winifredae Wheeler, Figs. 19 and 20, two body hairs, X418. Carebara lignata Westwood, Figs. 21-23 -21, head in anterior view, X108; 22, profile of worker larva, X18; 23, left mandible in anterior view, X245.
Paedalgus termitolestes Wheeler, Figs. 24-27 -24 and 25, two body hairs, X329; 26, head in anterior view, X132; 27, left mandible in anterior view, X303.




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Psyche
[December
Pheidologeton affinis (Jerdon)
(PI. 6, figs. 17-18)
SEXUAL (?) LARVA: Length straight from end to end 8 mm; length from head to anus through spiracles about 12 mrn. Voluminous, plump and turgid, bean-shaped. Head exceedingly minute, on the ventral surface near the anterior end. Mandibles somewhat smaller ; apical tcooth vestigial ; only one medial tooth. Otherwise similar to diversus worker larva. (Material studied: six larvae from Dutch New Guinea; hairs broken off.)
Genus Oligomyrmex Mayr
Short and very stout; prothorax forming a short, very stout neck which is bent ventrally to a right angle; dorsal profile C-shaped, ventral sinuate; diameter greatest at ab- dominal sornites IV and V. Body hairs short and moderately numerous. Of two types : (1) deeply bifid, with the branches curling away from each other, the most abundant type, absent from the ventral surface of the thorax; (2) a few on the ventral surface, with short-bifid tip. Head hairs few, short, varying in arrangement and shape. Labrum small and subrectangular; posterior surface sparsely spinulose. Mandibles with a long slender apical tooth which is curved medially; a large subapical tooth on the anterior surface; an acute medial tooth arising from the posterior surface near the middle of the mandible; one or two additional medial teeth may be present. Maxillary and labial palps each represented by a cluster of four sensilla; galea a low knob.
Oligomyrmex parvicornis Fore1
(PI. 6, figs. 1-7)
MATURE WORKER LARVA: Length about 1.5 mm. Short and very stout; prothorax forming a short, very stout neck which is bent ventrally to a right angle; dorsal profile C- shaped, ventral sinuate; diameter greatest at abdominal somites IV-V. Anus ventral, with a posterior lip. Segmenta- tion indistinct. Mesothoracic spiracle a third larger than the metathoracic and first abdominal (which are equal), the others exceedingly minute (one-third the size of the mesothoracic). Integument of midventral surface of thorax



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l9531 Wheeler and Wheeler - Myrmicine Larvae 139 and abdominal somites I and 11 with a few long transverse rows of spinules. Body hairs moderately numerous, uni- formly distributed, short. Of two types: (1) deeply bifid, 0.036-0.054 mm, with the branches curling away from each other, the most abundant type, absent from the ventral surface of the thorax (a few of this type are trifid or have the branches denticulate), without alveolus and articular membrane; (2) a few hairs on the ventral surface, 0.018- 0.045 mm, with short-bifid tip, with alveolus and articular membrane. Head large; cranium suboctagonal in anterior view, slightly broader than long. Antennae with three (rarely two) sensilla, each bearing a short spinule. Head hairs few, short (0.018-0.036 mm), varying in arrangement and shape (simple or bifid or trifid or with short-bifid tip or long-branched with a few denticles.) Labrum small, short and broad (breadth 3~ length) ; subrectangular, with the ventral corners rounded; anterior surface with four minute hairs, four sensilla and a few spinules; ventral border spinulose; posterior surface with six isolated sen- silla and a few spinules. Mandibles heavily sclerotized; a trifle stout; apex forming a long slender tooth which is curved medially ; a large subapical tooth on the anterior surface; an acute medial tooth arising from the posterior surface near the middle of the mandible; one or two addi- tional medial teeth may be present. Maxillae with the apex paraboloidal; palp a cluster of four sensilla, two of which bear each a spinule and two a cap; galea a short knob with two sensilla. Anterior surface of labium sparsely spinulose, the spinules minute and in short rows; palp a cluster of four sensilla, two of which bear each a spinule and two a cap; a minute hair between each palp and the opening of the sericteries; the latter a short transverse slit. FIRST INSTAR LARVA: Length about 0.27 mm. Body short, stout and subovoidal. Head very large, ventral. Hairs simple, about 0.006 mm long. Integument of dorsal surface with spinules in short transverse rows.
SECOND INSTAR LARVA: Similar to the first instar but with hairs up to 0.009 rnm long.
YOUNG LARVA: Length about 0.73 mm. Short and stout with the prothorax curved ventrally to a right angle. Head very large. Body hairs very short (0.006-0.018 mm), most



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140 Psyche [December
hairs on the ventral surface straight, with simple or bifid tip; elsewhere varied (simple and straight or flexible, or with bifid tip or deeply bifid). Integument of dorsal surface of abdominal somites VI-x with spinules in short transverse rows; a few minute spinules on the venter of the prothorax. YOUNG LARVA: Length about 1.1 mm. Similar to mature larva.
Material studied: two dozen larvae from Queensland; courtesy of Dr. W. L. Brown.
Oligomyrmex jacobsoni F,orel
Length about 1.36 mm. Body hairs shorter. With a sensillum between each palp and the opening of the seric- teries. Otherwise as in pcbrvicornis. (Material studied : numerous larvae from Java.)
Oligomyrmex mjobergi Fore1
Very similar t,o parvicornis. (Material studied : numerous larvae from Queensland; courtesy of Dr. W. L. Brown.) Oligomyrmex thoracicus Weber
Weber, 1950, pp. 16-17 : "The 6-mm. cell contained worker and female pupae, the latter 3.3 mm. in length, and a few larvae which could have been only female, being 1.8-2.3 mm. long. Early worker pupae were enclmosed in the larval skin, the latter being 0.9 mm. long.
The female larvae were as
plump as those of Atta, one 1.8 mm. long having an ab- dominal diameter of 1.1 mm. and a head capsule of 0.25 mm. situated completely on the ventral side; no hairs were ap- parent. Worker larval skins on the other hand were covered with short hairs, bifurcate or trifurcate apically." Oligomyrmex (Aeromyrma) sundaicus Fore1
Very similar to parvicornis. (Material studied: 18 dam- aged larvae from Java.)
Genus EREBOMYRMA Wheeler
Short and stout; curved ventrally; posterior end conoidal and directed ventrally. Labrum small and subrectangular; the posterior surface sparsely spinulose. Mandibles with apex forming a 1,ong slender acute tooth which is curved