George C. Wheeler and Jeanette Wheeler.
The larva of Proatta (Hymenoptera: Formicidae).
Psyche 92(4):447-450, 1985.

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THE LARVA OF PROATTA
(HYMENOPTERA: FORMICIDAE)
BY GEORGE C. WHEELER AND JEANETTE WHEELER* Desert Research Institute
University of Nevada System
Reno, Nevada
When Fore1 established (1912) the genus Proatta he placed it in the tribe Attini, but later (1917) he removed it to a new tribe Proat- tini. Wheeler (1922) kept it there, but Emery in the Genera Insectorum (1922) placed it alone in the subtribe Proattini of the tribe Attini. Weber (1958): "While it is true that Proatta butteli is strikingly like an attine, this is taken here to be an example of convergence in worker morphology and not necessarily an indica- tion of phylogenetic relationships. The spinosity is especially like that of Mycocepurus ,...There is no evidence that Proatta is a fungus-grower and it is not considered here to be a member of the Attini."
For years we have yearned for larvae of Proatta in the hope that they might solve the problem. Hence we were very happy when Mr. M. W. Moffett generously sent us a supply-so happy, in fact, that we processed them immediately.
Genus Proatta Fore1
Profile attoid, but only slightly curved. Somites indistinct. Body hairs sparse, generally distributed. Antennae minute; slightly above midlength of cranium. Head hairs sparse, generally distributed. Mouth parts small. Mandible amblyoponoid, feebly sclerotized. Proatta butteli Fore1
Figure 1
Length (through spiracles) 2-2.6 mm. Profile attoid. Spiracles small, decreasing slightly posteriorly. Integument with rather long *Mailing address: 3358 NE 58th Avenue, Silver Springs, Florida 32688. Manuscript received by the editor October 2, 1985.



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Psyche
[Vol. 92
Figure I.
Proatta butelli larva. a, Head in anterior view, X 122; b, 3 types of body hairs, X400; c, larva in side view, X42; d, left mandible in anterior view, X640. rows of spinules. Body hairs sparse; generally distributed. Of 3 types: (1) 0.025-0.1 mm long, unbranched, smooth, slender, with tip more or less curved; (2) about 0.025 mm long, few, with bifid tip; (3) about 0.006 mm long, unbranched, smooth, few, on venter of thorax. Cranium subheptagonal, about 1% times broader than long. Antennae just above midlength of cranium; minute; with 3 sensilla each. Head hairs few; 0.013-0.056 mm long, unbranched, smooth, slightly curved. Mouth parts small. Labrum trilobed; anterior sur- face of each lateral lobe with 2-3 sensilla near ventral border; rnid- die lobe with a cluster of 3-4 sensilla near each ventrolateral corner. Mandible amblyoponoid; moderately sclerotized; moderately stout; apex a short slender tooth; a small subapical medial tooth. Maxilla adnate; subovoidal in anterior view; palp a small skewed peg with 5 (1 apical, 3 subapical and 1 basal) sensilla; galea a slender frustum with 2 apical sensilla. Labial palp a slight elevation with 5 sensilla; an isolated sensillum between each palp and the opening of the sericteries; the latter a short transverse slit. (Material studied:



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Table 1.
Comparison of Proatta, Myrmicocrypta and higher attines. Character Proatta
Myrmicocrypta Higher attines
Profile
attoid (but slightly curved)
attoid (but slightly curved) attoid (strongly curved) Somkes indistinct
indistinct
indistinct
Spiracle line
with a posterior curve
with a posterior curve J-shaped
Body hairs
sparse, short generally
short and restricted short and restricted distributed
Cranium genae not lobose genae not lobose genae lobose Head hairs few, generally distributed few, below level of antennae few to numerous, generally distributed
Mouth parts small small small
Mandibles amblyoponoid; feebly sclero- amblyoponoid; feebly sclero- attoid; feebly sclerotized; tized; no spinules tized; coarse spinules on coarsely spinulose basal 213
Maxillae short, wide and adnate short, wide and free long, narrow and adnate



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numerous larvae from Botanical Gardens, Singapore, courtesy of M. W. Moffett.)
The solution to the problem of relationship can be best provided in a table (Table 1) comparing simultaneously the larvae of Proatta, Myrmicocrypta [which Wheeler regarded (1910:329) as the most primitive of the fungus-growing ants] and the most specialized ( Cyphomyrmex, Trachymyrmex, Mycetosoritis, A cromyrmex and Atta). For a full understanding of the table one should refer to our 1948 and 1976 papers.
So what is the answer? We conclude that the larva of Proatta is definitely attine. We have a prejudice against attaching a small monotypic genus found locally in the Oriental Realm to a large wide-spread tribe in the Neotropical Realm; hence we had hoped that the larva would be either strongly attine or strongly non-attine. It is neither, but it is as good an attine as Myrmicocrypta. It lacks the coarse spinules on the mandibles, which is an attine character, but so does Apterostigma, which is otherwise like the higher attines. The weightiest evidence is said to be that Proatta is not known to be a fungus-grower; but is it really necessary that the ancestral attine already have that habit?
Fam. Formicidae, Subfam. Myrmicinae. Genera Insectorum Fasc. 174. 307 p.
Descriptions provisoires de genres, sous-genres et espkces de Formi- cides des Indes orientales. Rev. Suisse Zool. 20: 761 -774. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaud. Sci. Nat. 51: 230-253.
WEBER, N. A.
1958.
Nomenclatural notes on Proatta and Atta. Ent. News 69: 1- 13. WHEELER, G. C.
1948.
The larvae of the fungus-growing ants. Amer. Midland Natur. 40: 664-689.
WHEELER, G. C., AND JEANETTE WHEELER.
1976.
Ant larvae: review and synthesis. Ent. Soc. Washington Memoir No. 7, 108 p.
WHEELER, W. M.
1910.
Ants. Columbia Univ. Press, New York. 663 p. 1922.
The ants collected by the American Museum Congo Expedition. Bull. Amer. Mus. Nat. Hist. 45: 39-269, 22 pi.



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