NORTH CAROLINA MARINE ALGAE. XI. A NEW SPECIES OF HELMINTHOCLADIA (LIAGORACEAE,NEMALIALES, RHODOPHYTA) WITH A REAPPRAISAL OF THE GENERIC LIMITS OF HELMINTHOCLADIA AND HELMINTHORA1

A new species in the Liagoraceae (Nemaliales) having vegetative and male reproductive characteristics usually associated with the genus Helminthora is assigned to Helminthocladia (as Helminthocladia andersonii Searles & Lewis) on the basis of the shape of the conical carpogonial protoplast, three-celled carpogonial filament, development of the carposporophyte from both cells formed by division of the zygote and development of the involucre without the formation of a bridge around the zygote or formation of rhizoids from the involucre. All of these are consistent characteristics of Helminthocladia and distinguish its species from those of Helminthora.     

NORTH CAROLINA MARINE ALGAE. IX. ONSLOWIA ENDOPHYTICA GEN. ET SP. NOV. (PHAEOPHYTA,SPHACELARIALES) AND NOTES ON OTHER NEW RECORDS FOR NORTH CAROLINA1

Four benthic algae are reported here for the first time in the North Carolina flora. The new brown algal genus and species, Onslowia endophytica Searles, is described as an endophyte of Halymenia floridana from the North Carolina continental shelf. New records of Boodleopsis pusilla and Naccaria corymbosa from North Carolina constitute range extensions of these tropical species on the American coast north from Florida. Blastophysa rhizopus, an endophyte and epiphyte known from the North Atlantic coast of Europe and America as well as the Caribbean is reported from North Carolina for the first time and in a new host, Predaea feldmannii.     

MOLECULAR PHYLOGENY OF DISCOSPORANGIUM MESARTHROCARPUM (PHAEOPHYCEAE) WITH A REINSTATEMENT OF THE ORDER DISCOSPORANGIALES1

A molecular phylogenetic analysis of the little‐studied filamentous brown alga Discosporangium mesarthrocarpum (Meneghini) Hauck using rbcL and partial 18S rDNA sequences revealed that the species forms a monophyletic clade with Choristocarpus tenellus (Kütz.) Zanardini that is sister to all other brown algae. Although D. mesarthrocarpum has unique disk‐shaped plurilocular reproductive organs, D. mesarthrocarpum and C. tenellus share the following basic morphological features, which are considered to be plesiomorphic characters in the brown algae: (1) apical (and diffuse) growth; (2) uniseriate, subdichotomously branched filaments; (3) multiple chloroplasts per cell without pyrenoids; and (4) lack of heterotrichy and of phaeophycean hairs. The rbcL DNA sequence of an Australian D. mesarthrocarpum specimen showed considerable deviation from Mediterranean and Macaronesian specimens. Therefore, the presence of a second species in the genus is suggested; however, the taxonomic treatment of this putative species is not pursued in the present report. Regarding the higher‐ranking systematic position of D. mesarthrocarpum, reinstatement of Discosporangiaceae and Discosporangiales is proposed, and the inclusion of Choristocarpaceae in the order is also suggested. Under short‐day and long‐day culture conditions at 15°C–25°C, Mediterranean D. mesarthrocarpum exhibited a direct type of life history, with a succession of uniseriate filamentous thalli bearing characteristic disk‐shaped plurilocular zoidangia, but thalli did not survive at 10°C and below.     

THE DYNAMICS OF TWO HYBRID ZONES IN APPALACHIAN SALAMANDERS OF THE GENUS PLETHODON

Two zones of intergradation between populations of Plethodon have been studied for 18 and 20 years, respectively. The data consist of systematic scores of colors, made at least twice annually. Near Heintooga Overlook in the Balsam Mountains (Great Smoky Mountains National Park), the salamanders' cheeks are gray. Proceeding north toward the Smokies, there is increasing frequency and intensity of red color at two, four, and six miles. There has been no change in the scores at any location. The width of the zone and our failure to detect any change can be explained by assuming neutrality of the character and random diffusion during the probable time since contact between the two intergrading forms, which most likely took place after the Hypsithermal Interval, 8,000–5,000 BP. At Coweeta Hydrologic Laboratory in the Nantahala Mountains, Plethodon jordani and P. glutinosus hybridize at intermediate elevations. The lateral white spots of glutinosus decrease and the red on the legs of jordani increases with elevation from 685 m to 1,052 m. At the higher elevation, the proportion of animals scored as “pure” jordani declined significantly from 1974 to 1990, an indication that the hybrid zone is spreading upward. The rate of spread is too great to be explained by random diffusion, so selection for glutinosus characters is the best explanation. The rate of spread of the hybrid zone indicates that hybridization began 60–65 years ago, at the end of the time of intense timbering. Such human disturbances have caused hybridization in other organisms.     

渤海北部底栖海藻的初步研究

报道了渤海北部底栖海藻的种类组成、区系性质、群落结构和季节性变化。经调查,该海区隶属于蓝藻门、红藻门、褐藻门和绿藻门的底栖海藻共有１１９ 种,其中包括５７ 种经济海藻和７ 个新记录种。研究表明,渤海北部底栖海藻的温度性质以暖温带性为主,带有一定的亚热带性;其群落成分的季节性变化非常明显     

EFFECT OF LYSOZYME (MURAMIDASE) ON MARINE AND FRESHWATER BLUE-GREEN ALGAE1

Marine blue-green algae, Lyngbya Lagerheimii, Microcoleus chthonoplastes, Plectonema terebrans, Agmenellum quadruplicatum, and freshwater blue-green algae, Anacystis nidulans, Anabaena variabilis, Nostoc muscorura, and Oscillatoria sp. treated with lysozyme (muramidase) formed spheroplasts but not protoplasts. The time needed for spheroplast induction varied with the species. Approximate internal osmotic pressures of the blue-green algae were determined. Marine algae generally had a higher osmotic pressure than freshwater algae.