Urostomides striatus Jankowski 1964
Creators: name: Feng, Xiaochen
name: Zhuang, Wenbao
name: Li, Ran
name: Hu, Xiaozhong
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Chromista
Ciliophora
Armophorea
Metopida
Apometopidae
Urostomides
Urostomides striatus

description: Urostomides striatus (McMurrich, 1884) Jankowski, 1964
(Figs 7–9; Table 1)
1884 Metopus striatus sp. nov. – McMurrich, Am. Nat., 18: 830.
1888 Metopides striata —Stokes, J. Trenton Nat. Hist. Soc., 1, fig. 11 on p. 186.
1927 Metopus striatus —Kahl, Arch. Protistenkd., 57, fig. 17i on p. 152.
1932 Metopus striatus —Kahl, Tierwelt Dtl., 21, fig. 70 on p. 414.
1964 Metopus striatus —Jankowski, Arch. Protistenkd., 107, figs. 11, 12 on pp. 202, 203.
1980 Metopus striatus —Foissner, Ber. Nat. Med. Ver. Salzbg., 5, fig. 10a, b on pp. 80, 81.
1992 Metopus striatus —Foissner et al., figs 4w, x, 88–93, 97, 98 on pp. 409, 417.
2017 Urostomides striatus —Bourland et al., Eur. J. Protistol., 61, fig 9 on p. 214.
aMeasurements in μm.
bExcluding perizonal stripe rows.Abbreviations:CV, coefficient of variation (%); M, median; Max, maximum;Min, minimum; N, number of specimens examined;SD, standard deviation.
Remarks
Metopus striatus has been described several times based on live observation (McMurrich 1884, Stokes 1888, Kahl 1927, 1932, Jankowski 1964, Foissner 1980). Jankowski (1964, 2007) regarded it as the type species of the subgenus Metopus (Urostomides) and the genus Urostomides, respectively. Recently, Bourland et al. (2017) redescribed the species in detail. Actually, the morphological and molecular indicators of the Chinese population closely resemble those of Idaho and Czech Republic strains (Bourland et al. 2017). However, there exist two significant distinctions between these populations (see details below).
Improved diagnosis
Cell size 65–90 × 30–50 μm in vivo, obpyriform to triangular. Sharpened at the posterior end or pulled out into a tapered tail. About 13–26 somatic kineties, of which 5–11 extend to the preoral dome. Four or five distinctly elongated caudal cilia at the rear end of the cell. Perizonal stripe without false kineties. Usually 40 adoral membranelles.Adoral zone makes about 180° turn around long axis.
Voucher slide
One voucher slide (registration number: FXC2021120202-01) with protargol-stained specimens is deposited in the Ocean University of China in Qingdao, China.
Morphological description of Chinese population
Body size 65–90 × 30–45 μm in vivo, 78 × 44 μm on average, length:width ratio 2.0: 1 in vivo on average, ranging from 1.6: 1 to 2.6: 1; about 76 × 44 μm in protargol-stained specimens. Outline broadly clavate, with a sharp or tail-like posterior end (Fig. 7A–D). Preoral dome rounded, distinctly wider than the posterior end, projects from the body proper, and occupies about 74% of body length (Fig. 7A–D). Macronucleus more or less globular, about 17 μm in diameter in vivo, located in mid-body; one globular micronucleus, about 4.7 μm in diameter in vivo, usually adjacent to macronucleus (Fig. 7L). Contractile vacuole, terminal, obconical to rounded (Fig. 7A, G). Cytoplasm yellow to brownish (Fig. 7B–D). Cortical granules colourless in vivo, about 0.3 μm across (Fig. 7F, G). Swims at moderate pace while rotating on long axis.
Ordinary somatic and perizonal cilia, 8–14 μm long in vivo; four or five caudal cilia, 26–30 μm long (Fig. 7A, K). Somatic kineties, arranged in 19–26 rows (23 on average), including 8–11 (nine on average) dome kineties, composed of dikinetids. Dome kineties 1 and 2 widely spaced, about 8 μm apart in protargol-stained specimens. Perizonal stripe consists of four rows, without false kineties; proximal ends of perizonal rows 1 and 2 more or less at the same level, rows 3 and 4 slightly shorter proximally (Fig. 7N).
Adoral zone, comprising about 40 (range 33–46) membranelles, commences at the right margin of ventral surface, extends obliquely to the left margin of dorsal surface, making about 180° turn, middle membranelles composed of three or four rows of basal bodies (Fig. 7E, H, I). Paroral membrane diplostichomonad, commences at level of proximal end of adoral zone, consisting of two rows of monokinetids with different lengths, the right file about 24 μm long, the left file about 13 μm long in protargol preparations (Fig. 7M).
Morphogenesis (Figs8, 9)
The divisional mode of Urostomides striatus basically matches that of U. minimus (Kahl, 1927) comb. nov. However, there are several minor differences: (i) certain early dividers (like Fig. 9D, E) have not been observed in U. minimus, namely, for U. striatus the opisthe’s proximal adoral membranelles are formed by dome kineties one-to-one but U. minimus might not; (ii) as concerns U. striatus, there is no stage recognized during which the newly built adoral membranelle-like structures derived from some scattered kinetosomes owing to the dedifferentiation of OOP2, like U. minimus (Figs 4K, 5A, B). Besides, in U. minimus, there is a stage during which the anlage of paroral membrane in both proter and opisthe is composed of a relatively long row of monokinetids (like Fig. 5J). It is not sure that this stage also exists in U. striatus (might be Fig. 8K).
Phylogenetic analyses of two isolates
Partial SSU rRNA gene sequences of Urostomides minimus (Kahl, 1927) comb. nov. (GenBank: OR658907) and U. striatus (McMurrich, 1884) Jankowski, 1964 (GenBank: OR658908) are both 1604 bp long, with a guanine-cytosine (GC) content of 43.08% and 43.64%, respectively. All available SSU rRNA gene sequences of the genus Urostomides form a strongly supported clade (ML 94/BI 1.00), which divides into two subclades (Fig. 10). One comprises Urostomides campanula, U. caducus, and Urostomides sp., fully supported in both analyses. The other comprises U. darwini, U. spinosus, U. pullus, U. minimus, U. denarius, U. bacillatus, U. striatus, and Urostomides sp., with low support in ML and strong support in BI (ML 61/ BI 0.99). Urostomides minimus clusters together with U. pullus (KY025572) with high nodal support (ML 99/BI 1.00) (genetic distance = 0.0036; Supporting Information, Table S1); however, the SSU rRNA gene sequence of U. pullus is just about 1200 bp long, possibly resulting in the above considerably ‘similar’ comparisons with U. minimus (about 1600 bp long). The clade composed of the populations of U. striatus is statistically supported in both analyses (ML 87/BI 0.99); the genetic distances between our strain and nine other populations of U. striatus are similar (0.000 –0.005; Supporting Information, Table S1). The Apometopidae / Urostomides clade then clusters with the Metopidae + Clevelandellida clade with high supportive value (ML 97/BI 1.00)
description: Published as part of Feng, Xiaochen, Zhuang, Wenbao, Li, Ran & Hu, Xiaozhong, 2025, Ontogeny and phylogeny of the anaerobic genus Urostomides with supplementing morphological characterization of the type and one litle-known species (Alveolata: Ciliophora: Armophorea), pp. 1-19 in Zoological Journal of the Linnean Society (Statistics in Society) (Statistics in Society) 203 (2) on pages 10-14, DOI: 10.1093/zoolinnean/zlae055, http://zenodo.org/record/14971642