Research Article |
Corresponding author: Gi-Sik Min ( mingisik@inha.ac.kr ) Academic editor: Pavel Stoev
© 2023 Hee-Min Yang, Gi-Sik Min.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Yang H-M, Min G-S (2023) A new species of the genus Cephalodella (Rotifera, Monogononta) from Korea, with reports of four additional cephalodellid species. ZooKeys 1141: 185-199. https://doi.org/10.3897/zookeys.1141.91147
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A new monogonont rotifer, Cephalodella binoculata sp. nov., was described from a soil sample collected in Korea. The new species is morphologically similar to C. carina but is distinguished by having two frontal eyespots, a vitellarium with eight nuclei, and the shape of its fulcrum. We also described four other cephalodellid species collected in Korea; Cephalodella auriculata, C. catellina, C. gracilis, and C. tinca. Of these four species, C. gracilis and C. tinca were newly recorded in Korea. We provided the morphological characteristics of the five Cephalodella species along with photographs of trophi observed with a scanning electron microscope. Furthermore, we provided the mitochondrial cytochrome c oxidase subunit I gene sequences of the five species.
COI, morphology, new records, Notommatidae, rotifers, SEM, taxonomy
The genus Cephalodella Bory de St. Vincent, 1826 is one of the most species-rich taxa in the phylum Rotifera Cuvier, 1817, containing 171 species worldwide (
In Korea, a total of seven cephalodellid species have been recorded: Cephalodella auriculata (Müller, 1773), C. catellina (Müller, 1786), C. forficula (Ehrenberg, 1838), C. gibba (Ehrenberg, 1830), C. hoodii (Gosse, 1886), C. innesi Myers, 1924, and C. ventripes (Dixon-Nuttall, 1901) (
In this study, we identified five cephalodellid rotifers, one of which was a new species. Two species, Cephalodella gracilis (Ehrenberg, 1830) and C. tinca Wulfert, 1937 were newly recorded in Korea and two others, C. auriculata and C. catellina, have previously been recorded in Korea. However, since the first reported paper on rotifers in Korea (Turner, 1986) did not include descriptions for these two species, we have described the two Korean specimens in this study. Here, we provide the morphological characteristics of the five species along with the photographs of trophi observed with scanning electron microscope (SEM). In addition, we deciphered the mitochondrial cytochrome c oxidase subunit I (COI) gene sequences of the five species.
Specimens were collected and isolated from a pond, reservoir and soil samples (Fig.
Morphological identification of rotifers was based on descriptions of
Genomic DNA was extracted using a LaboPassTM Tissue Genomic DNA Isolation Kit Mini (Cosmo Genetech, Korea). Partial COI gene was amplified using the 30F/885R primers (
The maximum-likelihood (ML) tree was inferred based on the partial COI gene sequences of 11 notommatid species and one euchlanid species (Table
List of species for which COI sequence data was used for molecular analysis.
Family | Species | GenBank No. | Reference |
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Notommatidae | Cephalodella binoculata sp. nov. | ON898529 (759 bp) | This study |
Cephalodella auriculata (Müller, 1773) | ON898533 (315 bp) | ||
Cephalodella catellina (Müller, 1786) | ON898532 (759 bp) | ||
Cephalodella gracilis (Ehrenberg, 1830) | ON898535 (759 bp) | ||
Cephalodella tinca Wulfert, 1937 | ON898534 (660 bp) | ||
Cephalodella cf. gibba (Ehrenberg, 1830) | JX216594 (661 bp) |
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Eothinia elongata (Ehrenberg, 1832) | DQ079964 (660 bp) |
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Eosphora ehrenbergi Weber, 1918 | HQ444173 (646 bp) |
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Notommata allantois Wulfert, 1935 | MT521624 (661 bp) |
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Notommata codonella Harring & Myers, 1924 | DQ297785 (660 bp) |
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Pleurotrocha petromyzon Ehrenberg, 1830 | EU499803 (583 bp) |
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Euchlanidae (Outgroup) | Euchlanis dilatata Ehrenberg, 1830 | JX216599 (661 bp) |
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In the present study, we identified five cephalodellid species in Korea; C. auriculata, C. binoculata sp. nov., C. catellina, C. gracilis, and C. tinca. The new species, C. binoculata sp. nov., was distinguished from other cephalodellid species by a combination of the following characteristics: two distinct frontal eyespots, short tail and toes, vitellarium with eight nuclei, and the shape of the trophi components. Two species, C. gracilis and C. tinca were newly recorded in Korea. Cephalodella gracilis is a common species worldwide. However, the morphological characteristics of C. gracilis have been reported to exhibit high morphological variation (
In this study, we obtained partial COI sequences from each of the five species and constructed an ML tree using the sequences of 11 notommatid rotifers and one euchlanid rotifer. The sequence of Euchlanis dilatata Ehrenberg, 1830 was used as the outgroup. The final length of the sequence alignment was 561 bp, and the genetic distance between the notommatid species was 0.172–0.412 (Table
Species | GenBank No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
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Cephalodella binoculata sp. nov. | ON898529 | ||||||||||
Cephalodella auriculata | ON898533 | 0.251 | |||||||||
Cephalodella catellina | ON898532 | 0.274 | 0.335 | ||||||||
Cephalodella gracilis | ON898535 | 0.229 | 0.312 | 0.282 | |||||||
Cephalodella tinca | ON898534 | 0.243 | 0.321 | 0.267 | 0.293 | ||||||
Cephalodella cf. gibba | JX216594 | 0.297 | 0.412 | 0.323 | 0.289 | 0.293 | |||||
Eothinia elongata | DQ079964 | 0.293 | 0.374 | 0.349 | 0.363 | 0.331 | 0.373 | ||||
Eosphora ehrenbergi | HQ444173 | 0.321 | 0.386 | 0.327 | 0.306 | 0.319 | 0.351 | 0.309 | |||
Notommata allantois | MT521624 | 0.235 | 0.385 | 0.312 | 0.307 | 0.296 | 0.340 | 0.262 | 0.207 | ||
Notommata codonella | DQ297785 | 0.237 | 0.347 | 0.324 | 0.313 | 0.283 | 0.346 | 0.310 | 0.229 | 0.172 | |
Pleurotrocha petromyzon | EU499803 | 0.327 | 0.369 | 0.364 | 0.345 | 0.374 | 0.363 | 0.303 | 0.301 | 0.278 | 0.317 |
Phylum Rotifera Cuvier, 1817
Class Eurotatoria De Ridder, 1957
Subclass Monogononta Plate, 1889
Order Ploima Hudson & Gosse, 1886
Family Notommatidae Hudson & Gosse, 1886
Type locality. Soil from Incheon, Republic of Korea (37°24.788'N, 126°44.738'E), 19 Jun. 2019, Kyu-Seok Chae leg. Holotype. 1 female, glycerol permanent slide, NIBRIV0000896982. Paratype. 2 female, glycerol permanent slides, NIBRIV0000896983, NIBRIV0000896984; trophi preparation for SEM, NIBRIV0000896985.
Cephalodella binoculata sp. nov. was most similar to C. carina Wulfert, 1959 in terms of frontal eyes, type B virgate trophi, dorsally curved toes, total length/toe length ratio, and short tail. The new species, however, was distinguished from C. carina by the following characteristics: (1) the new species has two distinct eyespots, whereas C. carina has one small eyespot; (2) the vitellarium of the new species contains eight nuclei, while that of C. carina contains six; and (3) the fulcrum of the new species is straight and without extension at the distal end, while the fulcrum of C. carina is thicker at the distal end.
The new species also resembles C. gibboides Wulfert, 1951 and C. graciosa Wulfert, 1956. However, it is distinguished from C. gibboides by the shape of its manubrium and tail length. The manubrium of C. gibboides has a bump in the middle with no basal lamellae, whereas the new species has basal lamellae in the manubrium and no bumps in the middle. The shape of the distal end of the manubrium also differed between the two species. The tail of C. gibboides covers the foot, whereas that of the new species is short. The new species is distinguished from C. graciosa in several morphological characteristics as follows: (1) the trophi of the new species is symmetrical, while that of C. graciosa is asymmetrical; (2) the manubrium of the new species has basal lamellae, while that of C. graciosa does not; (3) the new species has two eyespots, while C. graciosa has one eyespot; and (4) the new species has eight nuclei in the vitellarium, while C. graciosa has six.
Female. Body moderately elongated and not laterally compressed (Figs
Characteristics of male and eggs remain unknown.
Measurement. Total length 134–155 μm, toe 26–29 μm, trophi 24–28 μm, ramus 8–9 μm, fulcrum 15–17 μm, manubrium 14–17 μm.
The specific name, binoculata, derived from the Latin word bi, meaning “two” and oculata, meaning “eyed”.
Pond in Incheon Metropolitan City, Republic of Korea (37°27.020'N, 126°39.345'E), 2 Dec. 2021, Hee-Min Yang leg. NIBRIV0000896986, 1 female, glycerol permanent slide.
The morphological characteristics of the Korean specimens generally corresponded to those reported in a previous study (
Partial COI sequence was obtained from one Korean specimen (
Reservoir in Wanju-gun, Jeollabuk-do, Republic of Korea (35°50.196'N, 127°00.975'E), 27 Mar. 2022, Hee-Min Yang leg. NIBRIV0000896987, 1 female, glycerol permanent slide.
Korean specimens of C. catellina had morphological characteristics that were generally consistent with those reported in previous studies (
Partial COI sequence was obtained from one Korean specimen (
Soil from Cheonan-si, Chungcheongnam-do, Republic of Korea (36°54.095'N, 127°12.380'E), 22 Jun. 2019, Hee-Min Yang leg. NIBRIV0000879592, 1 female, glycerol permanent slide.
The body size of the Korean specimens was 120–125 μm in length (Fig.
Cephalodella gracilis has been reported to have high morphological variation in the shape of the toes and trophi. The Korean specimen had dorsally curved toes that gradually tapered toward the end. The trophi shape of the Korean specimen did not correspond to a specific specimen but was most similar to that described by
Soil from Yeoju-si, Gyeonggi-do, Republic of Korea (37°18.483'N, 127°41.067'E), 26 Sep. 2019, Kyu-Seok Chae leg. NIBRIV0000895434, 1 female, glycerol permanent slide.
The body was 200–220 μm long, elongated, and laterally compressed (Fig.
Morphological characteristics of Korean C. tinca specimens corresponded well to the original description except for the size of body length. The body length of the Korean specimen was 200–220 μm, which was slightly smaller than the original description (260–280 μm) (
Partial COI sequence was obtained from one Korean specimen (
This study was supported by a grant from the National Institute of Biological Resources (