Click here for the original journal page (in Acrobat pdf format).

The text below is grayed out because it is not intended to be read. It is a necessarily imperfect OCR of the original and is only used by a search engine.

8

Vol.11: nosl-3

A USE OF CHROMOSOME NUMBERS IN THE STUDY OF

TAXONOMY OF THE LEPIDOPTERA AND NOTES ON

THE INTERNAL REPRODUCTIVE ANATOMY

by Kodo Maeki

The following report deals with the chromosome numbers observed in the germ cells of 16 species of Papilionidse which are found in Japan. Further data are presented concerning the testicular form and color, and the stages of the life cycle at which meiotic divisions have been seen to have taken place. These data are correlated with the known morphological relationships of these species, and this relationship is more clearly defined.

Testicular form is classified into three major types: separate, gourd-shaped, and conjugated. In the larvae of all species the testes are clearly separated, each testis being made up of four follicles. In certain groups this condition changes during development to a point where they become slightly adherent, having the appearance of a gourd or dumb-bell, or becoming completely conjugated and spherical. In these types the single testis has eight follicles. Table I presents the data concerning the distribution of these types during the various stages of development for the groups under discussion. These suggest a phylogenetic sequence wherein the separate condition appears most primitive, and the conjugated condition that of the derived forms. The latter form is found in most of the butterflies.

Table 1. Testis form during development in the Japanese Papilionidae.

In addition to the different shapes of testes that were found, coloration of their epithelial sheath was found to vary. Three distinct classes were found: yellow, pale blue, and red. The primitive genera (Parnassius, Luehdorfia, Graphium) have yellow or pale blue testes, while the derived ones (Byasa, Papilio) have them red-colored. These data, with the following on meiosis, are presented in Table 2.

1957

The Lepidopterists' Ne<ws

9

Table 2. Chromosome Number and Imaginal Testicular Form and Color for Sixteen Species of Japanese Papilionidas.

CHROMOSOME SPECIES                              NUMBER             TESTES FORM TESTES COLOR

Meiosis is observed in a few butterflies only in the pre-pupal and early pupal stages. This was found to hold true for all the species of Parnassius, Luehdorfia, Graphium, Byasa, and Papilio macilentus. In all the other members of the family considered here, spermatogenesis was not only found in these stages, but also in the imagos. However, in the imaginal testes, most meiosis was aberrant and led to the formation of apyrene spermatozoa.

The chromosomes of all of the species are dot-like, and the following haploid numbers were found: 20, 30, 31, and 62. 'J"he reman numerals given after the numbers for each species in Table I refer to the stage of spermatogenesis in which the determinations were made.

A correlation is found between morphology and chromosome numbers, with the most primitive species exhibiting the highest number of 62. The numbers 31, 30, and 20 occur in the progressively more specialized, or derived, forms.

Graphium sarpedon with 20 and G. doson with 30 chromosomes are closely related, and it can be observed that differences in chromosome numbers here appear to be associated with chromosomal fusion. In G. doson, with the 30 chromosomes, 20 are small and 10 large dots; whereas in G. sarpedon there are 20 dots, all of which are large. The most probable explanation is that the lower numbers have been derived by fusion of the 20 small chromosomes into 10 larger ones.

Biological Institute, Kwansei Gakuin University, Nishinomiya, JAPAN