George C. Wheeler and Jeanette Wheeler.
The larva of Leptanilla japonica, with notes on the genus (Hymenoptera: Formicidae: Leptanillinae).
Psyche 95:185-190, 1988.

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THE LARVA OF LEPTANILLA JAPONICA,
WITH NOTES ON THE GENUS
(HYMENOPTERA: FORMICIDAE: LEPTANILLINAE) BY GEORGE C. WHEELER AND JEANETTE WHEELER* Research Associates Florida Department of Agriculture We have previously described (1965) the larvae of three species of Leptanilla: revelierei Emery, swani Wheeler and esheri (Kutter). Now, thanks to the generosity of Dr. Keiichi Masuko, we are able to describe the fourth. We do not ordinarily describe and illustrate fully the larva of more than one species of a genus, but Leptanilla larvae are so extraordinary that we consider it advisable to describe as many species as possible. Perhaps by so doing we can convince skeptics (including us) that such creatures actually exist. Dr. Masuko has not only provided us with specimens but also with his manuscripts, from which we quote briefly (with his permis- sion). Dr. Masuko is the only myrmecologist who has seen living Leptanilla larvae. Furthermore, his observations necessitate changes in our previous descriptions. Hence we will begin with a complete revision of our generic characterization, which is also a characteri- zation of the subfamily.
Genus LEPTANILLA Emery
Elongate and very slender; slightly constricted at the metathorax; remainder of body straight and clavate. With a curious structure projecting anteroventrally from the ventral surface of the pro- thorax. Spiracles minute. A hemolymph feeding pore on each side of abdominal somite 111 or IV. Body hairs smooth and unbranched, minute hairs very abundant and uniformly distributed; a few long hairs sparsely scattered. Cranium thin; subpyriform in anterior view, at least a third longer than broad. Head hairs lacking. Anten- nae small; each on the ventral end of a narrow ridge; each with 2 sensilla. Labrum large and thin; posterior surface spinulose; lateral surfaces with a few long slender sharp-pointed teeth. Mandible *Mailing Address: George C. Wheeler and Jeanette Wheeler, 3358 NE 58th Avenue, Silver Springs, Florida 32688.
Manuscript received by the editor June 4, 1988.



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186 Psyche [VOI. 95
turned laterally (instead of medially as is usual with ant larvae); feebly sclerotized; with a long slender sharp-pointed apical tooth, which curves laterally; outer border furnished with several long slender sharp-pointed teeth; anterior surface with spinules in rows. Labium thin, flap-like and narrowed basally; each palp a ventro- lateral cluster of five sensilla.
The larvae of Leptanilla are unique among the 200 known genera of ant larvae in 3 characters: The prothoracic projection, the hemo- lymph feeding pores and the mandibles. The most significant of the 3 is the hemolymph feeding pores. We considered them to be spira- cles, because we could not find any structures that resembled spira- cles. One reason why is now apparent: the spiracles of L. japonica are of the same diameter as the base of a minute hair. Therefore even if we had seen a spiracle we would have considered it as the base of a broken-off hair. Another reason: no one had ever studied a live colony of Leptanilla. The solution of the problem is Masuko's discovery of "larval hemolymph feeding (LHF)":- Whenever the queen froze at the 4th abdominal segment, her mouthparts were placed near the posterior border on a side. "In this region a pair of strange structures is present. [Each] is externally a naked circular area bordered by a fringe of stiff hairs. . . . In the center of this area, a slit-like opening is located. . . . Histological sections were made [of] this region, revealing that this opening is internally attached to a short duct. . . . This duct is strongly bent and opens directly into the larval body cavity." "Since oral trophallaxis is totally absent in the species, LHF is the only way of obtaining nutrients by the queens. [The queens never feed on prey.] . . . L. japonica workers ordinarily performed LHF even close to the queens, in addition to the prey feeding." Leptanilla japonica Baroni-Urbani
Length (through spiracles) 1.2-1.7 mm. Elongate and very slender; slightly contricted at the metathorax; remainder of body straight and clavate. Anus posterior. With a peculiar complex struc- ture on the anteroventral surface of the prothorax. Spiracles minute (sometimes vestigial or absent) on T2, T3 and AI-AVIII. On AIV there is a pair of "hemolymph feeding pores" (~asuko, in prepara- tion). Integument of naked anterior portion of Tl with ridges and spinules; posterior portion with hairs similar to those on remainder



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19881 Wheeler & Wheeler - Leptanilla japonica 187 Figs. 1-7.
Larva of Leptanilla japonica. 1, Head in anterior view, X508; 2, head in side view, X397; 3, prothoracic projection in anterior view, X397; 4, larva in side view, X59; 5, left hemolymph feeding pore, X1042; 6, three types of body hairs, X508; 7, left mandible in anterior view, X962. of body. Body hairs unbranched, smooth and slightly curved. Of 3 types: (1) 0.003-0.006 mm long, numerous, uniformly distributed (except lacking on anterior portion of Tl and posterior portion of AX) and in transverse rows, each hair set in a slightly sclerotized shallow depression; (2) 0.019-0.088 mm long, with pointed tip, a few



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188 Psyche [VOI. 95
on each somite; (3) 0.069-0.088 mm long, with slightly enlarged flattened tip, on ventrolateral surfaces of A1-AV111. Cranium thin; subpyriform in anterior view; a third longer than broad. Antenna minute; with 2 sensilla at end of a long ridge. No head hairs. Labrum a large thin flap, a third broader than long, widest ven- trally; with 4 long slender sharp-pointed teeth on each lateral sur- face. Mandible turned laterally; apical half of medial surface heavily sclerotized; ending in a sharp-pointed apical tooth; anterior surface bearing about 4 long slender sharp-pointed teeth; with a wide blade bearing 4 long slender sharp-pointed teeth directed laterally. Max- illa (only partly visible) with a short base and a large lobate palp bearing 5 (1 apical and 4 subapical) sensilla; galea not seen. Labium a very thin flap, trapezoidal in anterior view, narrowed dorsally; palp represented by 5 sensilla on each ventrolateral corner; opening of sericteries a narrow slit on the ventral surface. (Material studied; 5 larvae from Kanagawa Pref., Japan, courtesy of Keiichi Masuko.) Of the 800 species of ant larvae we have studied, the leptanilline larvae are undoubtedly the most difficult to process. They are min- ute: 1.2- 1.7 mm long. They are very slender: they must be punctured in several places with a minute needle; these minute openings retard the transfer of the processing liquids. If KOH does completely dis- solve the internal tissues, the insoluble residue cannot be forced out without damaging the larval integument. Even when an integument is entirely cleaned the stain may never reach the head. After a stained integument is on a slide in balsam, it must be moved into the desired position for drawing. If the consistency of the balsam is not exactly right, the delicate integument will tear. Another difficulty: we have had so few specimens (3,3 and 5) that we dared not experiment.
Once a larva was stained and stably mounted we encountered difficulties of interpretation. The most exasperating was determin- ing the limits of the prothorax (of this we were never certain). No orthodox insect larva or adult should have spiracles on the prothorax. But some insects do: the mesothoracic spiracles migrate forward during development. But the spiracles of Leptanilla are difficult to find because of their minute size. Furthermore Masuko has found by SEM photography that spiracles may be vestigial or



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19881 Wheeler & Wheeler - Leptanilla japonica 189 lacking on some somites of some larvae.
Even if one does determine the extent of the prothorax and does locate the 4th abdominal somite, he still has to find the hemolymph feeding pores. That is easy in revelierei because of the heavily sclerotized rim. This rim is lacking in swani and japonica. In fact, in the latter two we are unable to locate the pores in our preserved specimens.
The larva of Leptanilla japonica is described and illustrated. The structures on abdominal somite IV, which have heretofore been regarded as the only spiracles, have been shown by Masuko to be hemolymph feeding pores. The larvae of the genus are characterized on the basis of the four known species.
MASIIK~, K. Larval hemolymph feeding in the ant Leptunillu juponicu: the second type with a larval specialized duct organ. (In preparation.) WHEEI~, G. C., AND JEANETTE WHEELER.
1965. The ant larvae of the subfamily
Leptanillinae. Psyche 72: 24-34.




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