ANATOMY OF MARELLIA REMIPES — CARBONELL 63 



(Surinam). According to this observer, M. clcarei lives on the float- 

 ing leaves of the water lilies (probably Nymphaea) and feeds on 

 them. He, too, mentions the unusual way in which the leaves are eaten 

 from their surface and describes the peculiar aspect of the partially 

 eaten leaves, so characteristic as to betray the presence of the insects 

 before they can actually be seen. In this very interesting paper, Wil- 

 lemse figures the mouth parts, wings, and external genitalia of 

 M. clearei. 



The present writer (Carbonell, 1957) has recently published an ac- 

 count of the habitat, activities, and oviposition of Marellia remipes, 

 which he found living on aquatic plants in shallow, permanent ponds 

 near the bed of the Cuareim River and affluents in northern Uruguay. 

 The insects live there on the floating leaves of the water poppy, Hy- 

 droclcis nymphoidcs Willd. (Butomaceae), on which they preferably 

 feed. The leaves of the plant are eaten in the same way as described 

 by Rosillo (1940) and Willemse (1948), i.e., directly from their upper 

 surfaces and never from the edges. An aspect of the habitat of 

 M. remipes in Uruguay is shown in plate i, where some partially eaten 

 leaves of the water poppy can be seen. As Willemse indicates, the 

 very aspect of these leaves is so characteristic as to reveal from a dis- 

 tance the presence of the insects. In the present writer's 1957 paper, 

 he confirms the observations already mentioned on the swimming of 

 the insects on the surface and under water, where they seek shelter 

 and hide for considerable periods of time among the submerged stems 

 of the aquatic plants. The (tgg pods of M. remipes are described in 

 that paper for the first time. They were found entirely submerged 

 in the water, adhering to the undersurface of the floating leaves of the 

 host plant. 



With reference to the host plants of the genus Marellia, it must be 

 remarked that those preferred by the species remipes belong to nearly 

 related families, while the water lilies on which clearei feeds belong 

 to one that is entirely unrelated to the other two. All these plants, 

 however, share a common characteristic : their leaves float horizontally 

 on the surface of the water, this circumstance being apparently a de- 

 cisive factor in determining the suitability of the plant to the needs 

 of the insects. 



The authors who have written on Marellia and Paiilinia, the only 

 genera of the family, have invariably remarked that these insects 

 present striking adaptations to the semiaquatic habitat. From an ana- 

 tomical viewpoint, they show notable adaptations to aquatic locomo- 

 tion in the structure of the tibiae, tibial spurs, and tarsi of the hind 

 legs. The structure of the hind legs has earned for the first described 



