INVESTIGADORES
VERA CANDIOTI Maria Florencia
artículos
Título:
Anatomy of anuran tadpoles from lentic water bodies: systematic relevance and correlation with feeding habits
Autor/es:
MARIA FLORENCIA VERA CANDIOTI
Revista:
ZOOTAXA
Editorial:
MAGNOLIA PRESS
Referencias:
Año: 2007 vol. 1600 p. 1 - 175
ISSN:
1175-5326
Resumen:
I studied anatomy, gut content, and the relationship among these traits in a set of anuran tadpoles. Larval stages (mainly
Gosner stages 3136) of nineteen species from various lentic environments were selected. Morphological characters
from the skeleton, musculature, oral apparatus and buccopharyngeal cavity were recorded, and a gut content analysis was
performed, with emphasis on food size distribution. Ordination techniques were applied in order to find patterns of similarity
in morphology and gut content. Canonical ordination methods were used to investigate the relationship among gut
content, morphology, and phylogeny in the species considered. The results show that several skeletal, muscular, and buccal
characters are relatively maintained within genera. Other features, which have appeared independently in different
lineages, reflect convergence phenomena in some cases related to ecological aspects. The configuration of the hyobranchial
skeleton, the development of the buccal floor depressor and levator muscles, and mouth gape width correlate with
prey size. In some species, morphology is clearly related with feeding. Tadpoles that ingest large food particles relative to
their body length present morphological traits attributable to macrophagy. Taxonomically unrelated tadpoles of Dendropsophus
nanus, D. microcephalus and Ceratophrys cranwelli possess hyobranchial skeletons with robust, rostrocaudally
long ceratohyals and reduced branchial baskets with short ceratobranchials devoid of lateral projections and spicules.
Lepidobatrachus llanensis tadpoles have laterally extended ceratohyals which, along with the lateral extension of the
jaws, result in a very wide oral apparatus and an ample buccopharyngeal cavity that allows the tadpole to ingest large and
whole prey; the branchial basket, although its ceratobranchials lack lateral projections and spicules, is slightly reduced in
area. The four species mentioned have a noticeable development of the buccal floor depressor muscles, and buccal cavities
with scarce filtering and entrapping structures. In Elachistocleis bicolor, Dermatonotus muelleri, Chiasmocleis panamensis,
and Xenopus laevis tadpoles, the branchial basket occupies >70% of the total hyobranchial skeleton area, and
the hypobranchial plates are highly reduced; the buccal floor levator muscles are well-developed, with an increased site
of attachment on the ventral expansion of the lateral process of the ceratohyal; the scarcity of the filtering structures in
the buccopharyngeal cavity are balanced with the great development of the branchial filters and secretory zones; all these
features relate to a diet based on small particles not significantly different from those of most other species; however,
experimental studies show that species with similar hyobranchial apparatus and muscles are the most efficient when
retaining minute particles. Finally, a large group of species present generalized morphological characters, such as a branchial
basket occupying about 50% of the total hyobranchial apparatus, intermediate values of mouth gape width and buccal
floor levator / depressor muscles ratio, and abundant filtering structures in the buccopharyngeal cavity; these species
feed frequently on food particles between 130% of the tadpole body length; however, in some of the species, macrophagous
diets are also reported in the literature, indicating that this morphology is flexible in more ample prey size ranges.