Showing papers in "Herpetological Monographs in 1989"
TL;DR: Anurans show a distinct dichotomy among the sources of energy used during larval growth and development, endotrophy and exotrophy, which allows more exact definitions of direct development, ovoviviparity, vivip parity, and related terms.
Abstract: Anurans show a distinct dichotomy among the sources of energy used during larval growth and development, endotrophy and exotrophy. This distinction allows more exact definitions of direct development, ovoviviparity, viviparity, and related terms. Endotrophic larvae, whether as a non-hatched embryo or a free-swimming, non-feeding tadpole, gain immediate developmental nutrition solely from parental sources, most frequently from the yolk allotted to each egg during vitellogenesis. Exotrophic larvae are always free-swimming, feeding tadpoles and orally consume numerous sources of energy not derived from a parent. The morphology of exotrophic tadpoles is surveyed with an emphasis on oral structures. Speculative scenarios and hypotheses concerning the functions of the various morphologies and the relationship of trophic structures to the ecology of the tadpoles are offered. Larval morphology and behavior permit the recognition of six developmental guilds of endotrophic larvae and 18 ecomorphological guilds of exotrophic larvae; these guilds are fully characterized.
397 citations
148 citations
TL;DR: In Lepidochelys olivacea, sexual differ- entiation of the gonad is barely initiated at hatching, therefore, sex-reversal after hatching is a possibility in this species.
Abstract: An electron microscopical and cytochemical investigation of the developing gonads of the Pacific Ridley Lepidochelys olivacea (Eschscholtz) reveals that extragonadal primordial germ cells of this sea turtle follow a migratory pathway similar to that of primordial germ cells in mammalian embryos, i.e., through the yolk sac and hind gut mesentery to the gonadal ridge. The undifferentiated gonad is formed by proliferation of mesothelial and mesenchymal cells, organized into epithelial medullary cords. Embryonic gonads incubated at the highest temperature (32? C) differentiated first. However, even 84 days after hatching, oogonia have not entered the prophase of the first meiotic division and no follicles are formed. Gonads of embryos incubated at 26-27.5? C were structurally similar to undifferentiated gonads; conspicuous medullary cords are connected to the surface epithelium containing most of the germ cells. Histochemical detection of steroidogenic tissue was positive in the adrenal glands, but negative in the gonads of both sexes. Finally, in all individuals, the Mullerian ducts are complete at hatching. In Lepidochelys olivacea, sexual differ- entiation of the gonad is barely initiated at hatching, therefore, sex-reversal after hatching is a possibility in this species.
47 citations
TL;DR: Multivariate analyses of variation in 30 scale characters for specimens of Lepidophyma from 63 Central American localities identify five morphological groups and suggest that the all-female populations found in Panama and most of Caribbean Costa Rica may be of non-hybrid ("spontaneous") origin.
Abstract: Multivariate analyses of variation in 30 scale characters for specimens of Lepidophyma from 63 Central American localities identify five morphological groups. Univariate comparisons of the groups diagnose four morphospecies. Two of these, L. smithii and L. mayae, appear to be bisexual. The all-female populations on the Pacific versant of Costa Rica are morphologically distinct and comprise L. reticulatum, which is sympatric with members of the L. flavimaculatum complex near Tilaran, Guanacaste.Province. The all-female populations found in Panama and most of Caribbean Costa Rica are not distinguishable from northern populations that contain males, and these are retained together in the L. flavimaculatum complex. Within this complex, the available data on morphology, karyotypes, and allozymes suggest that the all-female populations may be of non-hybrid ("spontaneous") origin.
20 citations