Pellaea zygophylla, a new combination for a distinctive & well-known but neglected fern.

Pellaea ovata is a widespread species, sexual diploid in Texas & northeastern Mexico but an apogamous triploid in northwestern Mexico, south to northern Argentina, & on Hispaniola. The type belongs to the southern, apogamous triploid form. Although these two forms have been discussed repeatedly in the literature, morphological distinctions between them have been overlooked and they have not been recognized taxonomically. However, they are distinct. Pellaea ovata s.s. has puberulent rachides & costae; pinnae usually 2-pinnate with a well-defined main axis & pinnules borne singly; fertile pinnules ovate, cordate basally & rounded apically. The sexual diploid form has rachides & costae glabrous; pinnae pseudo-dichotomously branched & pinnules usually paired; fertile pinnules narrowly rounded-trapeziform, obliquely truncate to cordate basally & truncate apically. Riddell named the sexual diploid form Pteris zygophylla, from which I give it the new combination Pellaea zygophylla.

Pellaea zygophylla, a new combination for a distinctive & well-known but neglected fern

Pellaea ovata is a widespread species, sexual diploid in Texas &northeastern Mexico but an apogamous triploid in northwestern Mexico, south to northern Argentina, &on Hispaniola. The type belongs to the southern, apogamous triploid form. Although these two forms have been discussed repeatedly in the literature, morphological distinctions between them have been overlooked and they have not been recognized taxonomically. However, they are distinct. Pellaea ovata s.s. has puberulent rachides & costae; pinnae usually 2-pinnate with a well-defined main axis &pinnules borne singly; fertile pinnules ovate, cordate basally &rounded apically. The sexual diploid form has rachides &costae glabrous; pinnae pseudo-dichotomously branched &pinnules usually paired; fertile pinnules narrowly rounded-trapeziform, obliquely truncate to cordate basally &truncate apically. Riddell named the sexual diploid form Pteris zygophylla, from which I give it the new combination Pellaea zygophylla.

Modified Method of Metaphase Plates Obtaining for Polyploid Fish Genera Carassius and Cobitis Karyotyping (Actinopterygii, Cypriniformes)

Modern methods for obtaining metaphase plates from the somatic cells of fish, most effective in the study of polyploid species, were selected and tested. The technique with CoCl2 and colchicine treatment is recommended on the basis of empirical data for representatives of the genera Carassius and Cobitis. Th e detailed description of this modified technique and characteristics of metaphase plates of Carassius auratus Linnaeus, 1758, Carassius carassius Linnaeus, 1758 and triploid form of Cobitis taenia Linnaeus, 1758 received under tested method is presented in the paper.

Electrophoretic studies on enzymes of diploid and triploid paragonimus westermani

SUMMARYAn enzyme analysis of diploid and triploid Paragonimus westermani was conducted using starch gel electrophoresis. In total, 16 enzymes, probably encoded by 18 loci, were studied for 3 populations of the diploid form sampled from 2 localities, and 4 populations of the triploid form from 4 localities. Comparison of the enzymes of the triploid and the diploid digeneans showed 5 different patterns; diaphorase (EC 1.6.2.2), glutamic-oxaloacetic transaminase (EC 2.6.1.1), hexokinase (EC 2.7.1.1), leucylglycylglycine aminopeptidase (EC 3.4.1.3), and phosphoglucomutase (EC 2.7.5.1). On the basis of the numbers of bands and their patterns, all individuals of the triploid are probably heterozygous at each of these 5 loci and homozygous at the remaining 13 loci. The occurrence of fixed heterozygotes found in triploid populations cannot be easily explained by only a single mutation. It is suggested that the variability may have been introduced by hybridization with a different sub-species or a closely related species and may, thus, have been maintained since the time of the origin of triploids.

Studies on the genus Apios. I. Chromosome number and distribution of Apios americana and A. priceana

Two sonatic chromosome numbers were found for the leguminous plant Apios americana Medikus, i.e., 22 and 33. The former was interpreted as diploid, and the latter, as triploid. The triploid form predominated in the northern range of the species. The diploid was represented in northern material by a single collection (from Medoc, Ontario). A collection of plants produced from seeds obtained from a site in Tennessee was uniformly diploid. A combination of triploidy and self-incompatibility is suggested as the cause of the apparent complete sterility of the species over much of its range. Characterization of individual clones indicated that at least three different triploids were in existence. One of these was distributed over much of the northern range of the species. Chromosome counts of Apios priceana Robinson, a rare and the only other known American species in the genus, showed it to be a diploid with 22 somatic chromosomes.

XIII.—The Cytology of a Diploid Bisexual Spider Beetle, Ptinus clavipes Panzer and its Triploid Gynogenetic form mobilis Moore

SynopsisThe chromosome constitution of the bisexual beetle Ptinus clavipes Panzer (2n = 18) and of its gynogenetic form P. clavipes f. mobilis Moore (3n = 27) have been investigated. The triploid mobilis lives in close association with the bisexual species and mates freely with the males. Eggs from virgin females never pass beyond the metaphase stage and successful completion of maturation is dependent on the presence of sperm. An endomitotic split is apparent in prophase chromosomes and leads to the formation of twenty-seven pseudobivalents which undergo a pseudomeiotic division. Only one maturation division has been observed. Although the fate of the activating sperm has not been resolved it is thought that sperm nuclei give rise to isolated haploid nuclei in some eggs and interfere with normal cleavage in others. Since the triploid form may also mate with males of Ptinus pusillus Sturm and P. fur. L. with reduced numbers of progeny the affinities of the gynogenetic form is discussed. This is the only known case of gynogenesis in Coleoptera.