ANATOMY OF MARELLIA REMIPES — CARBONELL 69 



The mandibles of Marellia (fig. 3), which is a typical broad-leaved 

 plant feeder, belong very definitely to the second or herbivorous type. 

 The teeth of the incisor lobes {il) have their edges extraordinarily 

 sharp and minutely jagged. The molar areas {ma) are armed with 

 very prominent marginal teeth, especially on the left jaw, where the 

 anterior part of the molar area shows two very long, upcurved teeth 

 with jagged edges. In this insect the left mandible (B, D) is noticea- 

 bly larger than the right one and broadly overlaps it when closed. 



The mandibles of Marellia rcmipes show, however, some features 

 that depart from the straight herbivorous type, which are correlated 

 with the unusual mode of feeding of these insects. As has been stated 

 in the introductory part of this paper, Marellia does not eat the leaves 

 from the edges, but gnaws holes on their surface instead. Sometimes 

 these holes do not come through the leaf, but only the upper paren- 

 chyma is eaten, leaving the network of veins, and the aerenchyma 

 below, intact. Commenting on this unusual way of feeding, Uvarov 

 (personal letter) pointed out to the writer that the study of the mouth 

 parts of the insects would surely disclose special adaptations to this 

 type of feeding. This inference proved to be true, since it can be seen 

 in the jaws of Marellia that the incisor lobes (fig. 3 C, D) are strongly 

 curved rearward, in such a way that when the insect stands on a leaf 

 of the host plant and lowers its head for feeding, it is not the apical 

 end of the incisor lobe that comes in contact with the leaf surface, 

 as would happen if it were straight, but a considerable length of the 

 convex toothed edge instead. In this way the sharp, jagged edges of 

 the incisor lobes are able to cut superficial pieces from the flat leaves, 

 and the insect does not need to attack them from their edges, which 

 in the case of floating leaves would be, if we can use an anthropo- 

 morphic word, impractical. 



Marellia is not, however, the only grasshopper that eats in this par- 

 ticular way. A similar way of feeding on the broad leaves of the 

 water hyacinth {Eichhornia aaurea) by the grasshopper Cornops 

 aquaticiim Br. has been reported by Covelo de Zolessi (1956). 



The maxillae. — The maxillae of Marellia remipes (fig. 4 A, B) have 

 the usual structure of the grasshopper maxillae, as it has been de- 

 scribed by Snodgrass (1928). The cardo (Ca) is roughly triangular ; 

 the stipes (St) is quadrate, with a differentiated palpifer (Pf). The 

 maxillary palpi are five-segmented. The galea (Ga) is membranous 

 and relatively narrow, and the lacinia (Lc) armed with a number of 

 very sharp apical teeth. The maxillae are slightly asymmetrical in 

 shape. 



