Journal of Oceanology and Limnology Vol. 38 No. 6, P. 1900-1906, 2020 https://doi.org/10.1007/s00343-019-9075-z

Description of changdensis sp. nov. (Rotifera: ) from Hunan Province, China*

WEI Nan1, 3 , ** , JERSABEK Christian D.2 , YANG Yufeng 3 , ** 1 South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510530, China 2 Department of Biosciences, University of Salzburg, A-5020 Salzburg, Austria 3 Department of Ecology and Institute of Hydrobiology, Jinan University, Guangzhou 510632, China

Received Mar. 19, 2019; accepted in principle May 16, 2019; accepted for publication Oct. 9, 2019 © Chinese Society for Oceanology and Limnology, Science Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract A new freshwater Cephalodella changdensis sp. nov. discovered in two locations in Changde, Hunan, China, is described morphologically. The new species is characterized by body shape moderately elongate, double eyespots frontally, toes conical and almost straight, about one fourth of total length, trophi type B (classifi cation after Wulfert, 1937), rami asymmetrical with a pair of long alulae, fulcrum inverted T-shaped (ventral/dorsal view) with dorsally directed distal projection (lateral view), and manubria asymmetrical, left one slightly longer and stronger, with J-shaped or crutch-shaped posterior ends.

Keyword : rotifer; new species; Cephalodella changdensis sp. nov.; ; trophi asymmetrical

1 INTRODUCTION Province, based on live observations and SEM examination of the trophi. The genus Cephalodella , belonging to family Notommatidae, is one of the most species-rich genera 2 MATERIAL AND METHOD of the Phylum Rotifera. At present, 163 valid morphospecies (including subspecies) have been were collected on fi ve occasions during documented worldwide (Nogrady and Pourriot, 1995; diff erent seasons in 2017 (March 20, September 16, Segers, 2007; Jersabek and Leitner, 2013). Many and December 13) and 2018 (June 22 and September species within Cephalodella show high similarity and 19) from two sites in the Huashan area at the foot of can be diff erentiated only by carefully examining Taiyangshan Hill, Changde City, Hunan Province, their trophi structure, which is diffi cult by light South China. One was in a fast-fl owing roadside microscopy or even by scanning electron microscopy creek, with abundant but patchily distributed (SEM) (De Smet and Verolet, 2016). In addition, submerged plant Limnophila sp. The other was in a identifi cation of Cephalodella should be based on small roadside concrete ditch, with fast-fl owing observation of live , in order to ascertain shallow water and unidentifi ed weeds on the bottom. presence or absence of eyespots and to properly Plankton samples from the two sites were collected establish body proportions and anatomical using a nylon net with 30-μm mesh size. Periphytic organization (Jersabek et al., 2011). This is why, rotifers from the roadside creek site were sampled by Nogrady and Pourriot (1995) considered it to be the rinsing submerged plants in a 30-μm mesh sieve using most taxonomically diffi cult genus among all rotifers. fi ltered water which was prepared on the spot by In China, less than 50 species of Cephalodella fi ltering the site water using a 30-μm net. From each have been recorded to date (Zhuge et al., 1998). Most sample two subsamples were taken, one for live of them are widely distributed, and only Cephalodella qionghaiensis Koste & Zhuge, 1998 was originally recorded in China and is still regarded as a Chinese * Supported by the National Natural Science Foundation of China (Nos. endemic. In the present study, C . changdensis sp. nov. 31601840, 41673080) is described from two sites in Changde City, Hunan ** Corresponding authors: [email protected]; [email protected] No.6 WEI et al.: C . changdensis sp. nov. from China 1901 observation, and the other was preserved in 4% Paratypes: four females from type locality, in a formaldehyde. A YSI-Pro Plus ® multiparameter permanent glycerine slide mount each. Two females instrument (YSI, USA) was pre-calibrated and used in the Museum of Biology, Sun Yat-sen University, for measuring in situ water temperature, salinity, pH, Guangzhou, China (SYS ROT00020, SYS and dissolved oxygen. ROT00021); one female in the Museum of Live samples were brought to the laboratory, and Hydrobiological Sciences, Institute of Hydrobiology, observed immediately using a BX51 microscope® Chinese Academy of Sciences, Wuhan, China (MHBS (Olympus, Japan) equipped with a TrueChrome R GD 2019010003); one female in the Academy of Metrics® camera (Tucsen, China) at a magnifi cation Natural Sciences of Drexel University, Philadelphia, of (400–1000)×. Preparation of trophi for light and USA (ANSP 2139). scanning electron microscopy (SEM) was done Additional material: numerous specimens from the following De Smet (1998), using a 10% NaOCl roadside creek site preserved in 4% formaldehyde solution to dissolve the soft parts. For taking scanning solution with added glycerine in Eppendorf vials, all electron micrographs, an EVO MA15® (ZEISS, kept in the collection of the fi rst author at South China Germany) microscope operated at 20 kV was used. Sea Environmental Research Center in South China Measurement of animals was done by using Tcapture® Institute of Environmental Sciences, Ministry of imaging software. Trophi elements were measured by Ecology and Environment, Guangzhou, China. ImageJ 1.46r (https://imagej.nih.gov/ij/) (Abràmoff et al., 2004). All measurements are presented as mean ± 3.3 Diagnosis standard deviation (SD), n= number of individuals Female about 150–160-μm long. Body moderately measured. Permanent mounts of voucher specimens elongate, weakly arched dorsally, almost fl at ventrally, were prepared in glycerine glass slides according to slightly compressed laterally. Head large, in average Jersabek et al. (2010). 26% of body length. Foot short, in average 12% of The classifi cation of Cephalodella trophi follows body length. Tail relatively large, almost as long as Wulfert (1937, 1938) and Fischer and Ahlrichs (2011), foot. Toes medium-sized, in average 24% of total while terminology of trophi structures follows De length, near conical, evenly tapering into acutely Smet and Verolet (2016). pointed tips, straight or very weakly recurved dorsally. Two frontal red eyespots. Trophi type B, moderately 3 TAXONOMY asymmetrical, with more strongly developed left side. Phylum ROTIFERA Cuvier, 1812 Rami with two acutely pointed, long alulae and Class EUROTATORIA De Ridder, 1957 9–10/7 (left/right) teeth on inner margins. Fulcrum Subclass Plate, 1889 relatively long, inverted T-shaped (ventral/dorsal Superorder PSEUDOTROCHA Kutikova, 1970 view), with dorsally recurved posterior half and large Order Hudson & Gosse, 1886 distal projection (lateral view). Manubria Family NOTOMMATIDAE Hudson & Gosse, 1886 asymmetrical, right side shorter and weaker, lacking Genus Cephalodella Bory de St. Vincent, 1826 typical lamellae on shaft, J-shaped or crutch-shaped Cephalodella changdensis sp. nov. in posterior half.

3.1 Type locality 3.4 Etymology

A fast - fl owing roadside creek (29°7′57.81″N, This species is named after the city of Changde, 111°40′30.58″E) and a small roadside concrete ditch Hunan Province, China, where the new species was (29°7′20.46″N, 111°39′49.19″E), near Maojiashan found. Village in Dingcheng District, Changde City, Hunan Province, China. 3.5 Description of female

3.2 Type material Body (Figs.1a & 2) moderately elongate and slightly compressed laterally, ventral margin almost Holotype: a female in a permanent glycerine glass straight or weakly curved, dorsal margin slightly slide mount deposited in the Museum of Biology, Sun gibbous when not well-extended. Lorica soft and Yat-sen University, Guangzhou, China (SYS smooth, trunk with three ill-defi ned plates, two ROT00019). dorsolaterally, one ventrally. Ventral and dorsal plates 1902 J. OCEANOL. LIMNOL., 38(6), 2020 Vol. 38

b

a

c

Fig.1 Cephalodella changdensis sp. nov. a. female habitus, lateral view; b. trophi, ventral view; c. trophi, lateral view (scale bar: a: 50 μm; b–c: 5 μm). separated by wide, posteriorly fl aring lateral sulci. widest posteriorly in dorsal/ventral view, weakly Connecting folds of plates conspicuous in well- defl exed, off set by distinct neckfold, occasionally extended animals. Dorsal plates separated by distinct with inconspicuous lips. Corona strongly oblique, V-shaped dorsal sulcus. Head relatively large, with markedly convex, often with protruding epipharyngeal average length 26% (22%–28%) of body length, elements. Dorsal antenna in posterior third of head. No.6 WEI et al.: C . changdensis sp. nov. from China 1903

a bcd

efg

h

Fig.2 Light microscope photographs of Cephalodella changdensis sp. nov. a–c. female habitus, lateral view; d. female habitus, ventral view; e. anterior part of body, lateral view; f. posterior part of body, lateral view; g. eye spots, dorsal view; h. neck region showing granular appearance of gastric glands, dorsal view (scale bar: a–d: 50 μm, e–h: 50 μm). Foot short, with average length 12% (12%–13%) of foot segment, with well-developed fold in dorsal. body length, very slightly defl exed, trapezoidal in Toes medium-sized, with average length 24% (23%– lateral view. Tail relatively large, almost as long as 25%) of total length, almost conical, broadest at their 1904 J. OCEANOL. LIMNOL., 38(6), 2020 Vol. 38

ab c

d e

Fig.3 Cephalodella changdensis sp. nov., scanning electron microscope photographs of trophi a. complete set, ventral view; b. complete set, lateral view; c. complete set, dorsolateral view; d. rami and unci, ventral view; e. rami and unci, lateral view (scale bar: a–c: 5 μm, d–e: 2 μm). base in lateral view, evenly tapering into sharply Trophi (Figs.1b, 1c & 3) virgate, type B according pointed tips, with almost straight ventral margin, and to Wulfert (1937, 1938) and Fischer and Ahlrichs straight or very weakly recurved dorsal margin. Brain (2011), moderately asymmetrical, with more strongly long, saccate, extending till neckfold, connecting to a reinforced left side. Rami composed of subbasal, pair of red-pigmented frontal eyespots. No basal and dorsal chambers. Subbasal rami chambers retrocerebral organ. Mastax large, slightly shorter strong asymmetrical. Right side fairly narrow, with than head. Oesophagus longer than mastax. Gastric larger, postero-anteriorly elongated triangular glands irregularly spherical in dorsal/lateral view, full fenestra. Left side relatively large and broad, with of rounded glandular granula. Stomach yellowish, smaller rounded-triangular fenestra. Left/right rami wall thick, indistinctly separated from moderately tip with 9–10/7 well-fused teeth on inner margin. long intestine. Anus underneath tip of tail. Basal rami chambers shallow with large fenestrae Protonephridial bladder very large when completely opening ventro-laterally, dorsal margin of chambers fi lled. Vitellarium with 8 nuclei. Pedal glands large, extending into acute and long, posteriorly pointed near comma-shaped in lateral view, extending into alulae. Dorsal chambers very shallow with very large trunk. lateral fenestrae, dorsal margin of chambers with No.6 WEI et al.: C . changdensis sp. nov. from China 1905 inconspicuous fl abella, ribbon-like shaft, composed 2018. It was present four times (except June 22, 2018) of fused sclerite elements. Fulcrum very long, narrow in plankton samples and two times (September 16, proximally in ventral view, gradually thickening 2017 and September 19, 2018) in periphyton samples towards distal part and widely extended bilaterally at (from the submerged macrophyte Limnophila sp.) distal end, giving it an inverted T-shaped appearance; from the creek, while a perennial occurrence of the in lateral view widest proximally, slightly narrower species was observed in plankton samples from the and with curved ventral margin towards distal part, ditch. Physico-chemical characteristics of the waters strongly recurved dorsally at distal end. No basal in both sites were: water temperature 9.4–27.5°C, fulcrum apophysis. Unci single-toothed, acute rod- salinity 0.09–0.28, pH 5.34–7.87, dissolved oxygen shaped with broadly expanded dorsal lamina. Left 7.50–12.00 mg/L. uncus stronger than right one. Tooth slightly longer than shaft. Manubria asymmetrical. Left manubrium 3.8 Comparison with related species slightly longer and stronger, with straight anterior The peculiar shape of the fulcrum in Cephalodella half, a longitudinal fenestra in median chamber, small changdensis sp. nov., being relatively long, inverted semicircular lamellae in dorsal manubrial chamber, T-shaped (ventral/dorsal view) with large dorsally and crutch-shaped posterior half. Right manubrium extended distal projection (lateral view), can hardly shorter and more slender, with anterior half and be confused with other congeners. manubrial foramen similar as in left manubrium, but Based on the revision of the genus Cephalodella posterior J-shaped or crutch-shaped. Pleural rod long, by Nogrady and Pourriot (1995), C . changdensis sp. S-shaped in lateral view. nov. keys out to C . pachydactyla Wulfert, 1937. It Male and eggs remain unknown. however diff ers from C . pachydactyla in the following 3.6 Measurement aspects: (1) body moderately elongate, without retrocerebral organ and salivary glands—compared to Body ( n= 8 swimming females): total length a more sturdy body, with retrocerebral organs and 150.1–158.4 μm (mean= 153.3±3.7 μm, n= 8), body several small plus one large salivary glands in length (excl. toes) 111.5–120.1 μm (mean= 116.8± C . pachydactyla ; (2) toes conical, evenly tapering to 4.1 μm, n= 8), head length 24.5–33.2 μm acute tips, straight or weakly recurved dorsally, (mean = 29.9±3.5 μm, n= 8), head height 31.5–34.0 μm whereas they are stout, with tips abruptly tapering and (mean = 32.7±1.0 μm, n= 8), trunk length 68.8– then curved dorsally in C . pachydactyla ; (3) fulcrum 73.2 μm (mean= 71.2±1.9 μm, n= 8), trunk width inverted T-shaped (ventral view), with dorsally 38.2–41.8 μm (mean = 40.0±1.8 μm, n= 3), foot length recurved distal part terminating in a large bilaterally 13.9–14.7 μm (mean= 14.5±0.4 μm, n= 8); toe length extended projection (lateral view), while the fulcrum 35.5–37.6 μm (mean = 36.5±0.9 μm, n= 8), ratio of distal end is spatulate (both in ventral and lateral total length/toe length 4.0–4.3 (mean= 4.2±0.1, n= 8). views) in C . pachydactyla ; (4) manubria clearly Trophi: ramus length 8.3–8.9 μm (mean= 8.6± asymmetrical, with the left side more strongly 0.2 μm, n= 5), ramus width (incl. alulae) 10.9–11.1 μm reinforced, while they are symmetrical, carrying (mean = 11.0±0.1 μm, n= 2), fulcrum length 15.6– diff erently shaped and relatively larger crutches in 17.7 μm (mean= 16.7±0.8 μm, n= 5), fulcrum width C . pachydactyla ; and (5) inner rami margins with 3.9–4.6 μm (mean= 4.3±0.4 μm, n= 3), right uncus 9–10/7 (left/right) teeth—but no teeth recognizable in length 6.9–7.7 μm (mean= 7.1±0.4 μm, n= 4), right C . pachydactyla . manubrium length 14.5–16.3 μm (mean= 15.2±0.7 μm, Owing to the presence of double frontal eyespots n= 5), left manubrium length 16.0–18.5 μm and type B trophi with crutched manubria, (mean = 17.7±1.1 μm, n= 4), right manubrium crutch Cephalodella changdensis sp. nov. also bears length 5.4–6.0 μm (mean= 5.6±0.3 μm, n= 4), left superfi cial similarity with its congeners C . cyclops manubrium crutch length 7.1–7.5 μm (mean= 7.2± Wulfert, 1937 and C . sterea (Gosse, 1887). However, 0.1 μm, n= 5). C . changdensis sp. nov. can be easily distinguished from C . cyclops by the two separated eyespots, the 3.7 Distribution and ecology relatively longer toes (1/3>toe length/total length To date, Cephalodella changdensis sp. nov. is only >1/5), the inverted T-shaped fulcrum (ventral view) known from the two sites in Changde City, collected and the asymmetrical manubria, whereas both on fi ve occasions during diff erent seasons in 2017 and eyespots within a common capsule, shorter toes (toe 1906 J. OCEANOL. LIMNOL., 38(6), 2020 Vol. 38 length/total length <1/5), a spatulate distal fulcrum 11 (7): 36-42. end (ventral view) and almost symmetrical manubria De Smet W H, Verolet M. 2016. Epibiotic rotifers of Gammarus can be recognized in C . cyclops . It is distinct from pulex (L.) (Crustacea, Amphipoda), with descriptions of taxa currently attributed to the highly variable two new species and notes on the terminology of the trophi. Zootaxa , 4107 (3): 301-320, https://doi.org/10. C . sterea , a complex mainly in morphology of the 11646/zootaxa.4107.3.1. trophi: rami with a pair of long pointed alulae and De Smet W H. 1998. Preparation of rotifer trophi for light and manubria only with small semicircular lamellae are scanning electron microscopy. Hydrobiologia , 387-388: characteristics of the new species, whereas only the 117-121, https://doi.org/10.1023/A:1017053518665. left ramus carrying a small alula, and manubria Fischer C, Ahlrichs W H. 2011. Revisiting the Cephalodella forming long lamellae that cover at least half of the trophi types. Hydrobiologia , 662 (1): 205-209, https://doi. shaft are typical features in C . sterea , in addition to org/10.1007/s10750-010-0497-z. the diff erently formed fulcrum, inverted T-shaped Gosse P H. 1887. Twenty-four more New Species of Rotifera. with dorsally recurved distal part in C . changdensis Journal of the Royal Microscopical Society , 7 (6): 861- 871, https://doi.org/10.1111/j.1365-2818.1887.tb01590.x. sp. nov. of the usual form (straight in lateral view, Jersabek C D, Bolortsetseg E, Taylor H L. 2010. Mongolian spatulate distal end) in C . sterea . Moreover, eyespots rotifers on microscope slides: instructions to permanent generally lie in a single capsule in C . sterea , but they specimen mounts from expedition material. Mongolian are separate in C . changdensis sp. nov. Another Journal of Biological Sciences , 8 (1): 51-57, https://doi. species that shows superfi cial resemblance to the new org/10.22353/mjbs.2010.08.06 species, in terms of trophi morphology, is C . dentata Jersabek C D, Leitner M F. 2013. The Rotifer World Catalog. Wulfert, 1937. Both species have long alulae on both World Wide Web electronic publication. http://www. rami and asymmetrical manubria without distinct rotifera.hausdernatur.at/. Accessed on 2019-03-20. lamellae, but they can safely be diff erentiated by the Jersabek C D, Weithoff G, Weisse T. 2011. Cephalodella acidophila n. sp. (Monogononta: Notommatidae), a new absence of eyespots and the more slender toes in rotifer species from highly acidic mining lakes. Zootaxa , C . dentata . 2939 (1): 50-58, https://doi.org/10.11646/zootaxa.2939.1.2. Nogrady T, Pourriot R. 1995. Family Notommatidae. In : 4 DATA AVAILABILITY STATEMENT Rotifera. Volume 3: The Notommatidae and the Scaridiidae. In : Nogrady T ed. Guides to the Identifi cation The authors declare that the data supporting the of the Microinvertebrates of the Continental Waters of the fi ndings of this study are available within the article. World. SPB Academic Publishing, Amsterdam, The The original data of measurements will be available Hague. p.1-229, 239-248. on request from the fi rst author. Segers H. 2007. Annotated checklist of the rotifers (Phylum Rotifera), with notes on nomenclature, taxonomy and 5 ACKNOWLEDGMENT distribution. Zootaxa , 1564 (1): 1-104, https://doi.org/10. 11646/zootaxa.1564.1.1. The authors would like to thank LONG Aihong, Wulfert K. 1937. Beiträge zur Kenntnis der Rädertierfauna YU Wenbo and LIANG Diwen for their kind help in Deutschlands. Teil III. Archiv für Hydrobiologie , 31 : 592-635. sample collection. Comments and suggestions of the Wulfert K. 1938. Die Rädertiergattung Cephalodella Bory de reviewers are greatly appreciated. St. Vincent. Bestimmungsschlüssel. Archiv für Naturgeschichte , 7 : 137-152. References Zhuge Y, Huang X F, Koste W. 1998. Rotifera recorded from China, 1893-1997, with remarks on their composition and Abràmoff M D, Magalhães P J, Ram S J. 2004. Image distribution. 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