Colpdidium zelihayildizae, Yildiz & O & V, 2021

Yildiz, İsmail, 2021, Morphology and phylogeny of a new soil ciliate, Colpodidium zelihayildizae n. sp. (Ciliophora, Nassophorea, Colpodidiidae), from Van, Turkey, Turkish Journal of Zoology 45 (4), pp. 304-313 : 311-312

4.1. Comparison of C. zelihayildizae n. sp. its relatives

Since the establishment of the genus Colpodidium by Wilbert (1982), 5 nominal species, namely C. caudatum , C. horribile , C. trichocystiferum , C. microstoma , and C. bradburyarum , have been assigned to this genus. C. zelihayildizae n. sp. can be easily distinguished from C. bradburyarum by its anteriorly directed horn-shaped buccal cavity, more dikinetids in the paroral membrane (20 vs. 8–10), and a single macronucleus. The present species should be compared with its other 4 relatives.

C. zelihayildizae n. sp. is much similar to the type species described by Wilbert (1982) in terms of its general body shape, location of the macronucleus, and the position of NO1, according to the information obtained from the photomicrographs and illustrations.However, since the author evaluated C. caudatum as a member of the class Colpodea , there have been serious errors and misinterpretations in the descriptions of the somatic and oral ciliature ( Foissner, 1990; Foissner, 1995; Foissner et al., 2002). However, it can be understood from the drawings that the 2 kinetosome pairs located on the left edge of the paroral membrane, which is located at a short distance from it, may be NO1. However, C. zelihayildizae n. sp. can be distinguished from the Wilbert (1982) population by its higher number of paroral dikinetids (20 vs. 17) and the organization of NO2 and NO3. It was not possible to compare the other characters because the original type population did not contain further details. Foissner (1995) and Foissner et al. (2002) redescribed the C. caudatum populations obtained from soil samples collected from various geographical regions (Costa-Rica, Namibia, and China). C. zelihayildizae n. sp. can be distinguished from the C. caudatum populations by the location of its buccal cavity (slightly below the equatorial plane vs. slightly above the equatorial plane in the populations from Costa-Rica and Namibia, while it is on the equatorial plane in the population from China), location of NO1 (distal end of paroral membrane and very close to it vs. behind the distal end of paroral membrane in the population from China), and number of kinetosome pairs in the paroral membrane (consistently 20 vs. 12−14, 12−13, and 14−19 in the populations from Costa-Rica, Namibia and China, respectively).

In terms of its general body shape, C. zelihayildizae n. sp. resembles C. horribile . However, the present species differs from it by the absence of extrusomes, body size (50 × 20 µm vs. 60 × 30 µm), number of somatic kineties (19−22 vs. 23−26), the position of NO1 (close to the distal end of the paroral dikinetids vs. behind the paroral membrane and slightly right of it), location of the macronucleus (last third of the cell vs. mid-body), and number of dikinetid paroral membranes (consistently 20 vs. 19−33) ( Foissner et al., 2002).

C. zelihayildizae n. sp. can be easily distinguished from C. trichocystiferum by the absence of extrusomes, its body size (40−60 µm vs. 35−50 µm), position of the macronucleus (last third vs. anterior half of the body), number of somatic kineties (19−22 vs. 17−18), number of paroral dikinetids (20 vs. 15−19), and position of NO1 (the distal end of the paroral membrane vs. behind the paroral membrane) ( Foissner et al., 2002).

C. zelihayildizae n. sp. can be distinguished from C. microstoma by its body size 40−60 µm vs. 55−80 µm), the location of NO1 (distal end of paroral membrane vs. behind the paroral membrane), position of the buccal cavity (slightly below the equatorial plane vs. in the anterior half), number of the somatic kineties (19−22 vs. 23−26), and number of paroral dikinetids (20 vs. 8−10) ( Foissner et al., 2002).

4.2. Phylogenetic analyses

To date, the genus Colpodidium comprises 6 species, namely C. caudatum , C. horribile , C. trichocystiferum , C. microstoma , C. barburyarum, and C. zelihayildizae n. sp. Gene sequence data of C. horribile , C. trichocystiferum , C. microstoma , and C. barburyarum are currently unavailable, and the remaining 2 species and an undescribed Colpodidiidae sp. were included in the present phylogenetic tree. Both the ML and BI methods used for the phylogenetic analysis suggested that the genus Colpodidium is monophyletic. C. zelihayildizae n. sp. was clustered with C. caudatum , and then strongly supported as a sister to Apocolpodidium etoschense , while Colpodidiidae sp. was fully supported in the basal position of the family Colpodiidae ( Figure 5 ). These results were in agreement with those of previous studies ( Breiner et al., 2008; Fan et al., 2014; Zhang et al., 2014).

Nomenclatural acts: This study and the nomenclatural acts that it contains. Have been registered in Zoobank. The LSID for this publication is: urn:lsid:zoobank.org:pub:48FFFA1C-F83D-4B54-A3E6-CD19FD63FEAB .

Figures

Figure 5. Phylogenetic tree obtained from SSU rRNA gene sequences analyses using ML and BI methods to show the position of C. zelihayildizae (in red and bold). The numbers on the nodes represent the bootstrap values of the ML analysis and posterior probabilities of BI analysis, respectively. Full support in both analyses (100% ML and 1.00 BI) is marked with a bold circle. The scale bar indicates 9 substitutions per 100 nucleotide positions.