Algae of Quitobaquito: A Spring-Fed Impoundment in Organ Pipe Cactus National Monument

Abstract

A lis of algae collected from Quitobaquito in Organ Pipe Cactus National Monument in southwestern Arizona is given along with a description of Cosmarium garrolense var. minor var. nov. The purpose of this paper is to present a list of algae identified in collections made at Quitobaquito in Organ Pipe Cactus National Monument in December, 1962 and on September 5, 1964. The only other algal collections, known to the authors, from this area were made by Cameron (1962) when he collected Nostoc ellipsosporum and N. muscorum in soil samples from a nearby hillside and a few specimens collected by Drouet and Hevly in October, 1960 (in Cameron, 1963 and 1964). Quitobaquito is a spring-fed impoundment located in Organ Pipe Cactus National Monument in southwestern Arizona (Fig. 1). It is a shallow desert watering hole surrounded by mesquite and cottonwood trees and its water supply comes via a small ditch from a spring located about 100 yards away on the side of a hill. Bottom materials consist of silt and organic debris in which is rooted an abundant growth of emergent vegetation. Heavy growths of filamentous algae also cover the bottom. Of particular interest is the presence of a subspecies of the desert minnow, Cyprinodon macularis (Cole, 1963). The principal rocks of the area are Pre-Cambrian schists and gneisses, mesozoic intrusive and extrusive rocks, and paleozoic sedimentary rocks (Bryan, 1922). The spring-waters have been analyzed only twice, once November 11, 1917, and by the authors on September 5, 1964 (see Table 1). Both values measured for total hardness are above 120 p.p.m. which indicates that this is a hard-water habitat. These data are to be expected; the Water Atlas of the United States (Miller, 1963) places Quitobaquito in the zone of 180 to 240 p.p.m. hardness as calcium carbonate. Further examination of Table 1 shows that the impound1 Contribution No. 169 from the Department of Natural Science. Field work supported by a grant from the American Philosophical Society.