Search

Twenty species of aquatic oligochaetes are reported from Costa Rica, El Salvador, Guatemala, Nicaragua, and Honduras. Species are in the families Aeolosomatidae, Opistocystidae, and Naididae. Setal measurements are cited for each species and compared with measurements from other parts of the range. Seven of the species are cosmopolitan and seven show neotropical affinities, while only two show nearctic relationships. Two species, Pristina menoni and Dero plumosa, are reported for the first time from the Western Hemisphere. The Central American republics have very few recorded species of aquatic oligochaetes, although some of the terrestrial species have been studied. Over a decade has been spent in gathering these few collections, and since no additional effort is anticipated in the near future, it is deemed appropriate to publish these records.

The response of macroinvertebrates to the progressive decomposition of the American lotus Nelumbo lutea (Willd.) Pers. was examined. Macroinvertebrate densities increased significantly with the onset and progressive senescence of the leaves, as reflected by decreasing chlorophyll a concentrations. The chironomid Polypedilum nymphaeorum Maschwitz and three species of Naididae exhibited positive responses to presumably increasing levels of food as leaf decomposition progressed. P. nymphaeorum larvae probably switched from feeding on periphyton to utilization of decomposing plant tissue and associated microbial decomposers once the Nelumbo leaves began to decompose. Naididae did not become abundant on the leaves until the onset of initial leaf decomposition. Densities of the carnivorous chironomid Ablabesmyia philosphagnos Beck and Beck were more closely related to the age of the leaves than to prey availability, older leaves having been colonized by several generations of individuals while the younger leaves had been colonized by only one

Population and reproductive dynamics of Nais communis were studied from August 1982 to November 1983 in an Ozaukee Co., Wisconsin, limnocrene. Population density was significantly (P 0.05) correlation of percentage of worms undergoing paratomy to environmental physico-chemical parameters and worm density. Mean aSD doubling time for the field population of N. communis was 13.57 4 13.00 days. INTRODUCTION Naidid oligochaetes are primarily freshwater organisms, although a few species can be found in brackish waters (Brinkhurst and Jamieson, 1971). Large seasonal fluctuations in density have been observed for many naidid species from a variety of habitats (e.g., Dyga and Lubyanov, 1980; Frenzel, 1981, 1983; Learner et al., 1978; Loden, 1981; McElhone, 1978). Often, a complete absence of naidids is noted during certain months (e.g., Frenzel, 1981, 1983; Learner et al., 1978; Loden, 1981). Reproduction in the Naididae is generally asexual by paratomy or fragmentation. Asexual reproduction is observed throughout the majority of the life cycle in most species (Frenzel, 1983; Learner et al., 1978; Loden, 1981; McElhone, 1978; Pfannkuche, 1979, 1981). Sexual reproduction in naidids usually takes place during a particular time of the year and can be short-lived (Frenzel, 1983; Hiltunen, 1967; Poddubnaya, 1968). The purpose of this study was to examine the population and reproductive dynamics of Nais communis Piguet from a Wisconsin limnocrene, a spring discharging into a small basin which overflows into a stream channel. Furthermore, several abiotic and biotic parameters were correlated in an attempt to characterize and quantify the intrinsic and extrinsic factors regulating N. communis population and reproductive parameters. MATERIALS AND METHODS The study site was located between 43?20' and 42?25'N, 87057'30" and 88?30"E in the township of Saukville, Ozaukee Co. (Ti iN, R2 1 E), Wisconsin. The limnocrene was roughly circular with a diam of approximately 5 m and a maximum depth of approximately 1.5 m. Physico-chemical parameters of the study site were measured immediately prior to collection of oligochaetes using APHA (1976) methods. Organic content of the substratum was estimated based on volatile matter. Four samples were collected from September 1982-September 1983 at 4-month intervals. Six replicates were measured in each collection by placing substratum in a crucible, drying at 100 C and weighing. These samples were then ashed in a muffle furnace at 600 C, cooled and weighed. The difference between dry weight and ashed weight was volatile matter (Lind, 1979). Naidid oligochaetes were sampled monthly from August 1982-April 1983 and twice monthly from May 1983-November 1983. Naidids were found only among the large floating mats of Spirogyra (Chlorophyta) which covered most of the limnocrene. Spirogyra was present during all months except February and March; hence, naidids were not

Dero digitata and Dero nivea were observed by scanning electron microscopy and light microscopy to have intermediate teeth in needle setae which gave them either a trifid or pectinate condition. There were seasonal differences in the percentages of worms having at least one intermediate-toothed needle seta for D. digitata. Overall, 48.1% of D. digitata and 100% of D. nivea examined had intermediate teeth. Percentage of needle setae with intermediate teeth per worm ranged from 41.3-68.4% for D. nivea and 1.4-4.8% for D. digitata. Plumosity on hair setae was observed for both species; projections giving the plumose appearance were up to 20 um long in D. digitata and those of D. nivea were up to 10 Am long. Generally, there was 100% plumosity of hair setae per worm if plumosity was present. Seasonal differences also were seen for plumosity in percentage of worms having this character. There was no correlation (P > 0.05) of seasonal differences to environmental physico-chemical parameters and no anterior to posterior trends for either setal character. The appearance of these previously undescribed setal characteristics in D. digitata and D. nivea and their intraspecific variation shed doubt on the validity of these taxonomic characters as used in the subgenus Dero. Whereas genitalia are used as primary taxonomic characters in most oligochaete families, the infrequent occurrence of sexually mature specimens among the Naididae dictates that many specific and generic differences be based on the presence or absence of setae as well as their morphology and abundance per fascicle. The use of setae in taxonomy implicitly assumes that setal characteristics for any species do not change and that there are few intraspecific

Presented herein are accounts of 12 species of Naididae and three of Tubificidae now known to occur in western Texas. Dero (D.) pectinata and Pristina americana are new to the North American fauna, having previously been reported only from neotropical regions. Nais communis, N. variabilis, Para- nais litoralis, Pristina synclites, and Monopylephorus sp. are new to Texas. Chae- togaster diastrophus, Dero (Aulophorus) furcata, Dero (D.) digitata, Pristina aequiseta, P. leidyi, Slavina appendiculata, Limnodrilus hoffmeisteri, and L. udekemianus are known from elsewhere in the state, but their presence in western Texas considerably extends their known ranges.

Rhabdostyla sp. preferentially infested Dero (Dero) nivea in an alkaline bog stream from June 1982 to December 1983. Rhabdostyla occurred infrequently on two other species of naidid oligochaetes but were absent from nonliving substrates, algae, macrophytes and other invertebrates. Seasonal abundance peaks of Rhabdostyla occurred in October of 1982 and September-October of 1983 coincident with abundance peaks of D. nivea. Prevalence of host infestation ranged from 7.5-100% when infestations were present. Overall mean number of Rhabdostyla, 1 SE per D. nivea, was 4.8-i-0.2; means of individual sampling periods ranged from 2.0/worm to 13.1/ worm. Up to .36 Rhabdostyla were present on individual D. nivea. Frequency distributions were significantly (P

present in the dorsal bundles of III and VI (IV?), but Brinkhurst noted that the illustration seems to show their presence in II. An alternative interpretation of the drawing is that the dorsal setal bundle of IV in the illustration might actually be the opposite dorsal bundle of III; as with the Florida specimens, dorsal setae may have been absent from IV. There are several errors in Chen's paper, but the editors comment in a footnote that because of wartime conditions in China at that time, Chen was unable to examine proofs prior to publication. Nevertheless, in our opinion an absence of dorsal setae from segment IV of the Florida specimens does not warrant the description of a new species, as virtually all other taxonomic characters are identical to those illustrated or described in the original publication. The species is not abundant at the Florida locality. Subsequent intensive collecting at the same site produced no additional specimens.

Larval development of the caryophyllaeid cestode Glaridacris confusa occurs in aquatic annelids of the families Tubificidae and Naididae. Procercoids possess a cercomer; the scolex and gonads are well developed. North American caryophyllaeid cestodes parasitize catostomid and cyprinid fishes; oligochaete annelids serve as their intermediate hosts. Glaridacris confusa Hunter is one of the five species currently assigned to the genus Glaridacris Cooper. Yamaguti (1959) correctly listed this species as G. confusa (not the G. confusus of Hunter, 1929) since the generic name is feminine. G. confusa has been recorded from Ictiobus bubalus Raf. and Ictiobus sp. from the Rock River, Illinois and the Mississippi River, Iowa (Hunter, 1929); from Carpiodes carpio (Raf.), Lake Texoma, Oklahoma (Self and Timmons, 1955); and from I. bubalus, I. cyprinellus (Val.) and I. niger Raf., Lake Texoma (Self and Campbell, 1956). This is the first account on the life cycle of G. confusa. Experiments conducted with G. catostomi Cooper and G. oligorchis Haderlie showed that oligochaetes of the genera Limnodrilus and Tubifex serve as intermediate hosts (McCrae, 1961; Calentine and Fredrickson

The distribution of aquatic oligochaetes in Texas and Oklahoma is discussed. Nais magnaseta is described from Texas and Pristina unidentata is described from Oklahoma. Morphometric characteristics of specimens from these states are compared with those from other regions. Among several collections of aquatic oligochaetes obtained over the years, or sent to me from Oklahoma and Texas, there appear two undescribed species and some distributional data worthy of record. Of the 15 species discussed, 11 are new to the fauna of this area and most of these extend the known range into the southwestern United States.

Immature tubificid worms (Oligochaeta) are very difficult to identify. No complete key exists even for the majority of mature Scandinavian species, and the specialist using conventional techniques has to be very experienced. Starch-gel electrophoresis followed by staining for non-specific esterases has been used as a complement to morphological methods (Milbrink and Nyman 1973). Zymograms of several aquatic oligochaetes are presented (Fig. 1) representing the families Naididae, Tubificidae, Lumbriculidae, and Lumbricidae. A key for identifying Scandinavian freshwater tubificids by morphological methods is in preparation and the inclusion of similar esterase zymograms has been considered. Protein taxonomy has shown that several freshwater

The species of a caryophyllaeid cestode genus exhibit considerable variation in specificity for their oligochaete annelid intermediate hosts. Larvae of Monobothrium ulmeri, Monobothrium hunteri, and Biacetabulum biloculoides were specific for one annelid species. Glaridacris catostomi procercoids developed in members of 6 annelid species of 2 families. Monobothrium ingens developed in 3 genera of Tubificidae and Biacetabulum infrequens occurred in members of 4 tubificid genera. Glaridacris confusa developed in 3 species of 2 annelid families. The major factor affecting specificity involved hatching of the cestode eggs. Other contributing factors were host cellular and chemical responses and physical size of the annelid species. Caryophyllaeid cestodes are unsegmented helminths which commonly parasitize catostomid and cyprinid fishes in North America. Experimental studies on life cycles and larval development of American caryophyllaeids have been made by McCrae (1961), Calentine and Frederickson (1965), and Calentine (1967). Other experimental studies include Kennedy (1965) and Kulakowskaja (1962). Egg development occurs in water and the annelid intermediate hosts acquire infections by eating embryonated eggs. Procercoid larvae develop in the oligochaete's body cavity or seminal vesicles and are characterized by a scolex, primordia of gonads, and a cercomer. Fishes become infected by eating annelids containing procercoids. The present study was conducted in order to elucidate the nature of intermediate host specificity for seven North American caryophyllaeid species. MATERIALS AND METHODS Cestodes and fish hosts were: Biacetabulum infrequens Hunter, 1927, and Monobothrium ulmeri Calentine and Mackiewicz, 1966, from Moxostoma anisurum (Raf.), 1820, St. Croix River, Lakeland, Minnesota; Glaridacris confusa Hunter, 1929, and Monobothrium ingens Hunter, 1927, from Ictiobus bubalus Raf., 1818, St. Croix River, Lakeland, Minnesota; and Biacetabulum biloculoides Mackiewicz and McCrae, 1965, Glaridacris catostomi Cooper, 1920, and Monobothrium hunteri Mackiewicz, 1963, from Catostomus commersoni (Lacepede), 1803, Willow River, Lake Mallilieu impoundment, Hudson, Wisconsin. Cestode eggs were collected from gravid worms refrigerated in tap water, or by dissection. Following embryonation at room temperature, eggs Received for publication 18 November 1969. * Supported by Public Health Service grant R01 AI06605. were stored in tap water at 5 C. All feeding experiments were conducted at room temperature. Annelids were exposed to cestode eggs in a mud medium, usually for 24 hr. Hosts were then removed and cultured in mud under aeration at room temperature. Infected annelids were fixed in hot 70% alcohol or in Bouin's fluid; procercoids were fixed in AFA. All whole mounts were stained with Mayer's paracarmine. Annelids used were: Aulodrilus pigueti Kowalewski, 1914; Branchiura sowerbyi Beddard, 1892; Ilyodrilus (Tubifex) templetoni (Southern), 1909; Limnodrilus hoffmeisteri Claparede, 1862; Peloscolex multisetosus (Smith), 1900; and Tubifex tubifex (Muller), 1774; of the Tubificidae, and Dero digitata (Muller), 1773; Nais communis Piguet, 1906; Ophidonais serpentina (Muiiller), 1773; Stylaria lacustris (L.), 1767; and Uncinais uncinata (0rsted), 1842, of the Naididae.