Observations on the morphology and taxonomy of a marine ciliate species of the genus Diophrys (Ciliophora: Euplotida)

Abstract

The morphological features of a species of the genus Diophrys are described with special reference to ciliature and infraciliature. These characteristics consist of: (1) the oral ciliature composed of an adoral zone of organelles and a paroral formation, and (2) the frontal, ventral, left marginal, transverse, and caudal cirri. A biometric analysis was carried out taking into account 31 morphological features; these included: (1) body size and nuclear apparatus components; (2) size of the oral ciliature structures; (3) size of the different cirri; (4) relative distances between the transverse cirri and the poles; and (5) the length of cilia beyond the infraciliature. Comparisons were made with other species of the genus, taking into account 11 structural variables. The present paper: (1) defines the morphological characteristics of populations of D. appendiculata by completing descriptions of certain infraciliature structures, supplementing data of earlier studies by way of biometric analysis, and providing, by means of a morphometric survey, an assemblage of statistically treated data that may be used to make taxonomic determinations with greater precision. The genus Diophrys embraces several species of ciliates that are common in many marine habitats, especially in epibenthic zones of the continental shelf. Although these species were described by various workers (Agamaliev, 1967, 1983; Borror, 1972; Dragesco, 1963; Hartwig, 1973; Kahl, 1935; Kattar, 1970), there is a paucity of morphological data for individual species; e.g., Diophrys appendiculata (see Curds & Wu, 1983). We studied individuals of D. appendiculata, comparing their morphological features with other species of Diophrys. This paper shows: (1) morphological characteristics of a population of D. appendiculata; (2) morphological data obtained not only by us, but supplemented other data from the literature; (3) a biometric analysis of infraciliature and other structural characteristics, thus supplying statistical data on D. appendiculata; and (4) comparisons among different species of Diophrys that may be of taxonomic utility. MATERIALS AND METHODS Ciliates were collected from Castro Urdiales Beach (Santander, Spain) during 1989-1990. They were extracted from interstitial sediments using the procedure described by Fernandez-Leborans (1990). Specimens were studied using brightfield and phase-contrast microscopy. Ciliature and infraciliature were stained by the silver carbonate technique (Fernandez-Leborans & Castro de Zaldumbide, 1986a). Measurements for 80 individuals were obtained for each feature using a calibrated ocular micrometer. I This work was supported by C.I.C.Y.T. grant NAT90-0059. TRANS. AM. MICROSC. SOC., 113(1): 22-33. 1994. ? Copyright, 1994, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.35 on Fri, 02 Sep 2016 04:26:02 UTC All use subject to http://about.jstor.org/terms VOL. 113, NO. 1, JANUARY 1994 RESULTS General Morphology Specimens studied are 54-72 Am in length and 44-62 ,um wide. The body is oval and flattened dorsoventrally (Figs. 1-4). There are two elongated and curved macronuclei, one anterior and the other posterior. Each macronucleus is 23-33 ,um long and 5.3-7.2 ,im wide. Near each macronucleus there is a spherical micronucleus 2.8-3.0 Am in diameter. The ciliature is located primarily on the ventral surface. This ciliature forms two groups of cilia, namely the oral ciliature and the cirri. The Oral Ciliature The oral ciliature is arranged around the oral zone (Figs. 1, 4). This zone, measuring 31-40 Am long x 13-26 Am wide, occupies the left side of the anterior ventral surface. The oral ciliature is composed of the adoral zone of organelles (AO) and the paroral formation (PF). The adoral zone of organelles (AO) is situated on the left side of the oral area (Figs. 4, 5; Table I). It extends anteriorly so that some organelles reach the right anterior side of the ventral surface. The zone is 44-73 Am long and 8-13 jum wide in its median part. There are 30-32 organelles. The organelles in the posterior end of the adoral zone are shorter, so that the terminal organelle is composed of two rows of 2-4 kinetosomes per row. The organelle anterior to the terminal one possesses two rows of 4-8 kinetosomes per row. Each of the remaining organelles is composed of four rows of kinetosomes; three rows have 35-38 kinetosomes each, and the fourth row (the most anterior) has 3-4 kinetosomes. The paroral formations (PF) are located on the right side of the oral area. Its posterior end is situated near the posterior end of the adoral zone of organelles. The anterior end does not reach the zone of organelles. The paroral formations are made up of two parts, paroral formation 1 (PF1) and paroral formation 2 (PF2). Paroral formation 1, lying nearer and anterior to the adoral organelles, is 27-31 Am long and is composed of pairs of kinetosomes (diplostichomonad) (Fig. 5; Table I). A fibrillar structure, the subparoral fiber 1 (sfl), accompanies the PF1 throughout its length. Another thin structure, the suboral fiber (sof), originates from each pair of kinetosomes and extends transversally toward the medial part of the oral area. The PF2 delimits the right border of the oral area (Figs. 7-9; Table I). This is a complex structure, composed of three parts: (1) an anterior part, PF2 I, 714 Aim long and composed of 20-24 pairs of kinetosomes (diplostichomonad); (2) an intermediate part, PF2 II, 15-23 tim long with an ensemble of 108-114 kinetosomes (the majority of them are arranged in groups of three kinetosomes); and (3) a posterior part, PF2 III, 7-10 Aim long extending from the posterior end of the PF2 II to the lower limit of the adoral zone of organelles. PF2 III is composed of 18-20 pairs of kinetosomes. The PF2 is accompanied, throughout its length, by a fibrillar structure, the 23 This content downloaded from 157.55.39.35 on Fri, 02 Sep 2016 04:26:02 UTC All use subject to http://about.jstor.org/terms