Tetmemena cf. pustulata (Müller, 1786) Eigner, 1999

Omar, Atef & Jung, Jae-Ho, 2024, Disentangling the stylonychine ciliates (Ciliophora: Hypotricha): the establishment of two new genera using an integrative taxonomic approach, Zoological Journal of the Linnean Society (zlae 144) 202, pp. 1-40 : 27-32

publication ID	https://doi.org/10.1093/zoolinnean/zlae144
publication LSID	lsid:zoobank.org:pub:4532A0E-7137-4BDA-A278-74E4DB433382
DOI	https://doi.org/10.5281/zenodo.14811994
persistent identifier	https://treatment.plazi.org/id/FF66823D-FF81-6B1F-FF5B-8153FFBFFDF1
treatment provided by	Plazi
scientific name	Tetmemena cf. pustulata (Müller, 1786) Eigner, 1999
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Treatment

( Fig. 16 View Figure 16 ; Table 1 View Table 1 )

The list of synonyms of Tetmemena pustulata contains only populations with available illustrations showing dorsal kinety 4 shortened anteriorly.

1952 Stylonychia pustulata Ehrenberg, 1835 —Hashimoto, Zool. Mag., Tokyo 61: 332.

1998 Stylonychia pustulata Müller, 1786 —Foissner and Gschwind, Ber. Nat.-med. Ver. Salzburg 12:58 [description of German population; two voucher sliders were deposited in Biology Centre of the Upper Austrian Museum in Linz (LI), Austria].

2016 Tetmemena pustulata (Müller, 1786) Eigner, 1999 — Foissner, Denisia 35:845 [description of Venezuelan population; four voucher slides were deposited at the Biology Centre of the Upper Austrian Museum in Linz (LI), Austria].

2020 Tetmemena pustulata (Müller, 1786) Eigner, 1999 — Kaur, Shashi, Warren, Negi and Kamra, Int. J. Syst. Evol. Microbiol. 70:3939–3952 (description of Indian population; no voucher material available).

2021 Stylonychia cf. notophora View in CoL —Omar and Jung, J. Spec. Res. 10:308 [misidentification; two voucher slides (NNIBRPR20118 and NNIBRPR20119) of Korean population were deposited at the Nakdonggang National Institute of Biological Resources, South Korea].

Morphological description of the Korean population: The Korean population of Tetmemena cf. pustulata was not observed in vivo. However, it is very similar to Tetmemena indica , i.e. body is narrowly elliptical in outline, with a length:width ratio of 2.3–3.6:1. Posterior end of body slightly truncated to right and without distinct emargination ( Fig. 16A–H View Figure 16 ). Nuclear apparatus commences at ~19% of body length and ends at ~79%. Two macronuclear nodules and one or two micronuclei. Individual macronuclear nodules ellipsoidal, usually with irregular outline after protargol impregnation, in or slightly left to the midline of the body, 21–29 μm × 7–13 μm after protargol impregnation. Micronuclei usually attached to macronuclear nodules, spherical, 2–4 μm across ( Fig. 16B–D, F, H View Figure 16 ). Cirral pattern of Tetmemena cf. pustulata is identical in number and arrangement to that in T. indica . Right marginal row commences subapically at ~9% of body length and ends posteriorly near body end, composed of 21–28 cirri. Left marginal row commences at ~44% of body length and ends near posterior body end, composed of 12–19 cirri. Gap between posterior end of marginal rows wide and slightly shifted to right ( Fig. 16A, C View Figure 16 ).

Six dorsal kineties, including two dorsomarginal ones. Kinety 1 shortened anteriorly, possessing 18–27 bristles; kineties 2 and 3 bipolar, not curved anteriorly, possessing 15–23 and 11–18 dikinetids, respectively; kinety 4 shortened anteriorly, i.e. ~1 or 2 dikinetids shorter than kinety 3, and possessing 14–22 dikinetids. Dorsomarginal kineties 1 and 2 extend posteriorly over about one-third and one-quarter of cell length and possess 7–11 and 3–6 dikinetids, respectively. Three moderately widely spaced caudal cirri slightly shifted rightwards, ≤25 μm long after protargol impregnation, one each at end of kineties 1, 2, and 4 ( Fig. 16B, D–H View Figure 16 ).

Adoral zone occupies 46%–56% of body length and is composed of 27–37 membranelles. Distal end of adoral zone at average of 6% of body length (DE-value 0.11 on average). Bases of largest membranelles ~6 μm wide. Buccal cavity, i.e. the transverse distance between anterior end of paroral membrane and the opposite adoral membranelle on left side, 5–10 μm wide and narrowing posteriorly. Undulating membranes in Stylonychia pattern, i.e. parallel, straight, or slightly curved and sometimes slightly overlapping. Paroral membrane commences left to buccal cirrus at ~20% of body length, with a length of ~18 μm, and extends to near end of buccal vertex. Endoral membrane commences posterior to anterior end of paroral at ~24% of body length, with a length of ~19 μm, and extends to end of buccal vertex. Pharyngeal fibres extend transversely to right body margin ( Fig. 16A, C View Figure 16 ).

Phylogenetic analyses

The information on the rRNA gene sequences (18S–ITS1– 5.8S –ITS2–partial 28S) of the present five species is as follows: Apostylonychia baugilensis [2877 bp long, 45.63% GC content, accession number (Acc. No.) PQ037619], Apostylonychia notophorides (2878 bp long, 45.20% GC content, Acc. No. PQ037620), Antetetmemena minima (2828 bp long, 45.54% GC content, Acc. No. PQ037621), Tetmemena indica (2871 bp long, 45.52% GC content, Acc. No. PQ037622), and T. cf. pustulata (2843 bp long, 45.34% GC content, Acc. No. PQ037623). The rest of the available sequences from the same isolates of Pseudostylonychia obliquocaudata Omar et al., 2022 and Tetmemena polymorpha Omar et al., 2023 in the GenBank database have been submitted under the accession numbers PQ013660 and PQ013659, respectively.

The phylogenetic trees conducted using ML and BI analyses show rather similar topologies. Thus, only the ML tree of each dataset is presented, with both the bootstrap values (ML) and the posterior probabilities (BI) included ( Figs 17–19 View Figure 17 View Figure 18 View Figure 19 ). In the 18S rRNA gene tree, the five sequences are distributed within the stylonychine clade. Sequences of the genus Tetmemena form a large clade also containing five sequences identified as Sterkiella nova Foissner and Berger, 1999 (AF508771 and X03948), Onychodromus grandis Stein, 1859 (AJ310486), and Stylonychia notophora Stokes, 1885 (FM209297 and KY855573), which is divided into two subclades. The sequence of Tetmemena cf. pustulata is identical to one sequence identified as Tetmemena pustulata (MH000394) and two Stylonychia notophora sequences (Supporting Information, Table S2 View Table 2 ); together, they nest in one of the subclades with 12 other T. pustulata sequences and T. saprai , with low supporting values (64% ML, 0.63 BI). Tetmemena indica nests in the second subclade together with Onychodromus grandis and forms an adelphotaxon to sequences of Sterkiella nova , Tetmemena polymorpha , two sequences identified as T. bifaria , and one T. pustulata sequence in the ML tree, while it forms a soft polytomy with these two subclades in the BI tree. Sequences belong to Tetmemena species in this clade show nine binary and two asymmetric signature characters against the sequences of the genera Antetetmemena and Apostylonychia . Apostylonychia baugilensis and Apostylonychia notophorides cluster together with high (96% ML) to medium (0.94 BI) supporting values and together, they form a sister clade to Styxophrya quadricornuta with full supporting values. The three sequences form an adelphotaxon to the large clade comprising mainly Tetmemena spp. , with high supporting values (95% ML, 0.95 BI). The two Apostylonychia species show six binary and three asymmetric signature characters against sequences of the genera Antetetmemena and Tetmemena . The sequence of Antetetmemena minima is at the base of all the aforementioned sequences and sequences of the genus Pleurotricha Stein, 1859 with high (97% ML, 0.99 BI) supporting values and shows two binary and three asymmetric characters against all Tetmemena and Apostylonychia sequences. Furthermore, the Antetetmemena minima sequence shows a sequence similarity of 98.8% (19 nucleotides difference) and 98.4% (26 nucleotides difference) with the sequences of Apostylonychia baugilensis and Apostylonychia notophorides , respectively, and 97.2%–98.5% (24–39 nucleotides difference) with the sequences of the genus Tetmemena . According to the topology tests, the monophyly of the genus Tetmemena was rejected by both the weighted Kishino–Hasigawa test and the approximately unbiased test. Likewise, the monophyly of the three genera Tetmemena , Apostylonychia , and Antetetmemena together was also rejected by both tests. In contrast, the only monophyletic group is formed by the two sequences of the new genus Apostylonychia ( Table 2 View Table 2 ).

In all other phylogenetic analyses performed using the concatenated and single rRNA genes (18S–ITS1– 5.8S –ITS 2, 18S –ITS1– 5.8S –ITS2–partial 28S, ITS1– 5.8S –ITS2, and partial 28S), the sequences of the genus Tetmemena nest together ( Figs 18 View Figure 18 , 19 View Figure 19 ; Supporting Information, Figs S1 View Figure 1 , S 2 View Figure 2 ). The two new sequences of the genus Apostylonychia nest together with full support only in the 18S–ITS1– 5.8S –ITS2 and 18S–ITS1–5.8SITS2–partial 28S gene trees. In the phylogenetic tree constructed using the 18S–ITS1– 5.8S –ITS2 rRNA genes (2280 characters), Antetetmemena minima is a sister to the genus Apostylonychia with full support, whereas in the phylogenetic trees constructed using the 18S–ITS1– 5.8S –ITS2–partial 28S and the only partial 28S rRNA genes, it is a sister to the genus Tetmemena .