Frontonia schaefferi Bullington 1939
Creators: name: Pan, Xuming
name: Liu, Weiwei
name: Yi, Zhenzhen
name: Fan, Xinpeng
name: Al-Rasheid, Khaled A. S.
name: Lin, Xiaofeng
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Chromista
Ciliophora
Oligohymenophorea
Hymenostomatida
Frontoniidae
Frontonia
Frontonia schaefferi

description: Frontonia schaefferi Bullington, 1939 (Fig. 4; Tables 1, 2)   
When this species was first described by Bullington (1939), neither the details of its living morphology, nor a clearly-outlined diagnosis was given. Hence, an improved diagnosis based on both previous and present studies is supplied here.  
 Improved diagnosis: Marine or brackish Frontonia, about 95–120 × 50–65 μm in vivo, elliptical or reniform with anterior end broad and posterior end slightly narrowed; small buccal field about 20% of body length; about 59–80 somatic kineties; three vestibular and five postoral kineties; peniculi 1 and 2 each with four rows, peniculus 3 with two rows; macronucleus ellipsoidal, located in central region of body; one contractile vacuole, positioned on right-dorsal side at about 3/5 distance down body length and with about eight, long collecting canals.   
 Description of Shenzhen population: Size in vivo about 95–100 × 50–55 μm. Elliptical or reniform in outline with anterior end broad and posterior end slightly narrowed (Fig. 4A, B, H, I, K). Dorsoventrally flattened about 3:2 (Fig. 4M). Buccal cavity small and shallow, elliptical to triangular in outline, about 20 µm × 10 µm, which corresponds to about 20% of body length (Fig. 4J). Cytoplasm colourless to slightly grayish, often with many small black granules (3–4 µm across) at anterior end of body (Fig. 4A, H, I). A few small blue crystal granules (1–3 μm in diameter) distributed randomly in cytoplasm (Fig. 4A, H, I). Macronucleus ellipsoidal, about 25 × 15 μm, located in body centre (Fig. 4A). No micronucleus observed. One contractile vacuole, about 10 µm in diameter, positioned on right-dorsal side at about three-fifths distance down body length, with about eight long collecting canals (Fig. 4A, H): one contractile vacuole pore located on right-ventral surface (Fig. 4F). Extrusomes spindle-shaped, about 5 µm long, densely arranged beneath pellicle (Fig. 4L), approximately 20 µm long when extruded (Fig. 4N). Somatic cilia approximately 6 µm long. Locomotion by crawling slowly on substrate or by swimming in water with clockwise rotation about long body axis.   
General infraciliature as shown in Fig. 4E–G, O–Q. Anterior and postoral sutures conspicuous, both extending onto dorsal side (Fig. 4E, F). About 59 to 80 somatic kineties. Five postoral kineties with dikinetids, beginning below the oral and terminating on the postoral suture (Fig. 4E, F). Three vestibular kineties with densely arranged kinetosomes extending from anterior vertex of buccal cavity and terminating at postoral suture (Fig. 4G, O). Three conspicuous peniculi, about half of the length of the buccal cavity: peniculi 1 and 2 about equal in length, each composed of four rows of kinetosomes, about half length of buccal cavity; peniculus 3 slightly curved to right at anterior end, composed of two shorter kineties which are about equal in length (Fig. 4G, O). Single-rowed paroral membrane on right edge of buccal cavity running from anterior to posterior edge of buccal overture, with well-developed oral pharyngeal fibres in the buccal area (Fig. 4G, Q).  
 Comparison and remarks: Frontonia schaefferi Bullington, 1939 was originally reported by Bullington (1939) with only its infraciliature described. The Shenzhen population closely resembles that described by Bullington (1939) except for a minor difference in the body size in vivo (120 × 65 µm vs. 100 × 55 µm in Shenzhen population) which we believe is population-dependent.
description: Published as part of Pan, Xuming, Liu, Weiwei, Yi, Zhenzhen, Fan, Xinpeng, Al-Rasheid, Khaled A. S. & Lin, Xiaofeng, 2013, Studies on Three Diverse Frontonia Species (Ciliophora, Peniculida), with Brief Notes on 14 Marine or Brackish Congeners, pp. 35-49 in Acta Protozoologica 52 (1) on pages 42-44, DOI: 10.4467/16890027AP.13.004.0832, http://zenodo.org/record/13192853