Frontonia lynni, Long & Song & Gong & Hu & Ma & Zhu & Wang, 2005

Long, Hongan, Song, Weibo, Gong, Jun, Hu, Xiaozhong, Ma, Honggang, Zhu, Mingzhuang & Wang, Mei, 2005, Frontonia lynni n. sp., a new marine ciliate (Protozoa, Ciliophora, Hymenostomatida) from Qingdao, China, Zootaxa 1003 (1), pp. 57-64 : 58-59

Frontonia lynni n. sp. ( Figs. 1­3 ; Table 1)

Diagnosis: Marine Frontonia about 100–210 x 70–150 µm in vivo, body shape ellipsoidal, dorsoventrally strongly flattened of about 3:1 with conspicuously small buccal cavity. 71– 83 somatic, three vestibular and five postoral kineties. Peniculi 1 and 2 each with four rows, whereas peniculus 3 has five ciliary rows. Macronucleus ellipsoidal. Single contractile vacuole, equatorially located on the right margin. Extrusomes spindle­shaped.

Type location: A mesotrophic sand beach (salinity 26 ‰) in Qingdao (36°08 N, 120°43), China .

Type specimens: One holotype with silver nitrate impregnated specimens is deposited in the Natural History Museum, London, UK with registration number 2005:24:12. Two paratypes with silver nitrate impregnated specimens are deposited in the Laboratory of Protozoology , OUC (slides number: 2004111501­1, 2004111501­2) .

Dedication: We dedicate this species to Prof. Dr. Denis H. Lynn, University of Guelph, Canada, a world­famous protozoologist, who has greatly contributed to the ciliate taxonomy and systematics.

Description: Size highly variable, in vivo about 100–210 × 70–150 µm, but mostly 130–170 µm in length; ratio of length: width about 3:2. Body shape constant, ellipsoidal in outline when viewed from ventral or dorsal; right margin straight while left margin slightly convex ( Figs. 1 A­C; 3A, 3B). Both ends broadly rounded. Dorsoventrally conspicuously flattened about 3:1 ( Fig. 1G ). Macronucleus ellipsoidal, positioned at body center; micronucleus spherical, adjacent to macronucleus ( Fig. 1I ). One contractile vacuole, about 20 µm in diameter, positioned equatorially and conspicuously right of median. Extrusomes spindle­shaped, about 6 µm long, densely arranged in cortex ( Figs. 1D ; 3B, 3C, 3K ). Cytoplasm transparent, colorless to slightly grey­yellowish, usually filled with many food vacuoles (> 10 µm in diameter), as well as dark granules and crystals (3­5 µm across) ( Figs. 1C ; 3B ), containing bacteria, diatoms and other small ciliates ( Figs. 1A ; 3J ). Somatic cilia about 8 µm long. Movement mostly by gliding back and forth on substrate; when swimming, moderately rapid with rotation around the long axis of the cell.

Buccal cavity small and shallow, triangular in outline, occupying about 1/7 of body length ( Figs. 1A, 1B, 1J, 1K ; 3C ). Three short vestibular kineties (VK1–3) run from anterior vertex of cavity to postoral suture, with densely arranged kinetosomes ( Figs. 1H, 1J ; 3C, 3H ). Three inconspicuous peniculi deeply located on the left wall of cavity: peniculi 1 and 2 (P1, 2) about equally long, positioned close to each other, parallel to the edge of the left vestibular wall and each composed of four rows of kinetosomes; peniculus 3 (P3) slightly curved to right, composed of five relatively shorter kineties, of which two are complete, another two are slightly shortened and the leftmost one is about half the length of the two on the right ( Figs. 1J ; 3E ).

Single­rowed paroral membrane (PM) on the right edge of the buccal cavity runs from the anterior of the buccal overture to the posterior edge. Anterior portion of argentophilic line (AL) positioned parallel to paroral membrane ( Figs. 1J ; 3E ).

As with its congeners, silverline system as quadrangular cortical meshes that can be observed after silver nitrate impregnation ( Figs. 1E ; 3I ).

Abbreviations: CV = coefficiency of variation in %, Max = maximum, Mean = arithmetic mean, Min = minimum, n = number of individuals examined, SD = standard deviation, SE = standard error of arithmetic mean.

Figures

FIGURE 1. Frontonia lynni n. sp. live (A–D, F, G), after silver carbonate (H, I, K) and silver nitrate impregnation (E, J). (A) Ventral view of a typical specimen. (B) A slightly deformed individual. (C) Showing variations in body shape. (D) Part of pellicle, to show extrusomes. (E) Silverline pattern. (F, G) Left and apical views of the same specimen, to show the position of the contractile vacuole. Note that the body is strongly (!) flattened. (H, I) The infraciliature of the same cell, note the small oral apparatus. (J) Oral apparatus. (K) To show the anterior and postoral sutures. AL = argentophilic line; AS = anterior suture; P1–3 = peniculi 1–3; PK = postoral kineties; PM = paraoral membrane; PS = postoral suture; VK1–3 = vestibular kineties 1–3. Scale bars in (A, B) = 50 µm, in (H, I) = 40 µm, in (J) = 20 µm.

FIGURE 2. Ventral views (A, C, E, G) and oral field (B, D, F, H) of Frontonia ambigua (A, B, from Dragesco & Dragesco­Kernéis 1986), Frontonia marisalbi (C, D from Burkovsky, 1970) and Frontonia tchibisovae (E, F, from Burkovsky, 1970) after silver nitrate impregnation. Frontonia frigida (G, H, from Petz et al., 1995; G after protargol impregnation, H after silver nitrate impregnation). Scale bars = 30 µm.

FIGURE 3. Frontonia lynni n. sp. live (A–D), after protargol (J), silver carbonate (F, G, H, K) and silver nitrate impregnation (E, I). (A) Dorsal view. (B) Arrangements of extrusomes and cilia. (C) Buccal area, showing vestibular kineties (arrowhead) and extrusomes (arrow). (D) Dorsal view, showing the contractile vacuole. (E) Buccal area, arrowheads refer to peniculi, arrow marks argentophilic line. (F) Lateral view, showing anterior suture (arrowhead). (G) Lateral view, showing posterior suture (arrow). (H) Infraciliature of oral field, arrow marks postoral kineties, arrowheads indicate vestibular kineties. (I) Silverline system. (J) Lateral view, arrowheads mark ingested diatoms. (K) A part of pellicle, arrowhead refers to a single kinetosome, arrow shows a rest extrusome. Scale bars = 50 µm.