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Ptygura thalenoiensis Meksuwan, Pholpunthin & Segers, 2011 (Figs 7–8) We only found one specimen of this recently described, unmistakable species. The present record from Huguangyan Lake in Southern China is the third of this species, expanding its known range within the Oriental region beyond Cambodia (Segers et al., 2010) and its type locality in Thailand (Meksuwan et al., 2011).

Lecane zhanjiangensis sp. nov. (Figs 2–3) Diagnosis. Lorica longer than wide; dorsal plate anteriorly narrower, medially wider than ventral plate; head aperture margin of dorsal lorica plate protruding significantly beyond ventral plate, with antero-lateral corners forming large semicircular projections, serrated anteriorly with three to five minute spines; antero-lateral corners of ventral plate with large acutely pointed projections; ventral transverse fold incomplete; foot pseudosegment trapezoidal, non-projecting; two relatively short toes, parallel-sided proximally, tapering to acute tips in distal third, no claws; trophi modified malleate; rami asymmetrical, with rounded alulae; unci with one major and two or three minor teeth. Type locality. Littoral zone of the Shimenhe River outlet in Shimenhe Bay (N21° 24' 2.05", E110° 23' 12.30"), under the Shimen Bridge of Shenyang-Haikou Expressway (G15), Potou district, Zhanjiang City, Guangdong Province, China, distant from shore about 1.5 m, depth about 0.6 m, salinity 18.3‰, temperature 25.1?, pH 7.22, DO 3.86 mg /L, transparency 0.55 m, chlorophyll-a 5 µg /L, on 13 April, 2017. Holotype. A female in a permanent glycerine glass slide mount deposited in the Museum of Biology, Sun Yatsen University, Guangzhou, China (SYS ROT 00016). Paratypes. Four females from type locality, in a glycerine permanent slide mount each. Two females in the Museum of Biology, Sun Yat-sen University, Guangzhou, China (SYS ROT 00017, SYS ROT 00018); one female in the Museum of Hydrobiological Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China (MHBS R GD 2019010002); one female in the Academy of Natural Sciences of Drexel University, Philadelphia, USA (ANSP 2138). Etymology. This species is named after the city of Zhanjiang, Guangdong, where the new species was found. Description of female. Lorica (Fig. 2) relatively soft, easily deformed. Head protruding significantly in imperfectly contracted specimens, with two or three pairs of acute spines bilaterally. Head aperture margins ventrally and dorsally almost straight in the middle, dorsal head aperture margin clearly protruding beyond ventral plate. Antero-lateral parts of dorsal plate with large semicircular projections, each with a series of three to five minute, more or less acute spines medially; antero-lateral corners of ventral plate with broad-based, acutely pointed projections with smoothly curved, medially convex inner margins. Dorsal plate smooth, near elliptical in wellcontracted animals. Ventral plate weakly ornamented, near parallel-sided and longer than wide; anteriorly wider, medially narrower than dorsal plate. Posterior margins of dorsal and ventral plate convex, without projections. Deep lateral sulci in well-contracted specimens. Ventral plate with weak, incomplete transverse fold. Foot pseudosegment trapezoidal, sub-terminal, non-projecting. Prepedal fold broad, rounded posteriorly. Coxal plates rounded triangular. Two parallel-sided, relatively short toes, with straight inner margins and curved external edges, then tapering to pointed tips in distal third, no claws. Trophi modified malleate (Fig. 3). Fulcrum short and plank-shaped in lateral view, rounded distally, broadly curved dorso-ventrally. Rami weakly asymmetrical, both with rounded alulae. Unci slightly asymmetrical, with one major ventral, and two or three minor teeth dorsally. Manubria elongate, with posterior chambers extending up to curved tips. Male and eggs unknown. Measurements. Body (N = 10 females): lorica ventral plate length 87–95 µm (mean = 91± 3 µm), ventral plate width 52–60 µm (mean = 55± 3 µm), dorsal plate length 83–92 µm (mean = 88± 3 µm), dorsal plate width 59–70 µm (mean = 65± 3 µm), anterior aperture width 40–53 µm (mean = 45± 5 µm), toe length 29–32 µm (mean = 30± 1 µm); trophi (N = 5): right ramus length 8.9–11.4 µm (mean = 10.0± 1.1 µm), manubrium length 25.2–28.4 µm (mean = 26.3± 1.2 µm), first right uncus tooth length 11.4–12.0 µm (mean = 11.7± 0.3 µm). Distribution and ecology. Lecane zhanjiangensis sp. nov. was found in two locations in South China, one from the type locality with small numbers collected on 13 April, 2017 (Tab. 1) and one from another brackishwater site (N20° 1' 6.5", E110° 23' 17.45") in the Nandujiang River Estuary, Haikou City, Hainan Province with one specimen collected on 7 April, 2017. The ecological characteristics of the waters were: salinity 18.3 and 14.7 ‰, water temperature 25.1 and 26.4°C, pH 7.22 and 7.9, DO 3.86 and 6.70 mg /L, transparency 0.55 and 1.50 m, chlorophyll-a 5 and 4 µg /L respectively. The high salinity in the localities clearly indicates it is a true brackishmarine Lecane. It co-occurred with two other saltwater species, viz. Trichocerca marina (Daday, 1890) (Fig. 9) and a species from the Brachionus plicatilis - complex (Tab. 2) in the type locality and one Synchaeta sp. in the Nandujiang River Estuary site. Comments. The new species possibly is closely related to Lecane insulaconae Fontaneto, Segers & Melone, 2008, a marine Lecane described from the Adriatic Sea, near the outlet of the Isonzo River, Northern Italy. Main differences between the two species are as follows: (1) dorsal plate near elliptical with average ratio of length/ width 1.37 (1.27–1.47) in L. zhanjiangensis sp. nov. vs. almost circular in L. insulaconae with the ratio about 1.05, calculated from Fontaneto et al. (2008: Fig. 2), (2) antero-lateral projections on the ventral lorica plate drawn out into a single acutely pointed spine in the new species vs. bifid antero-lateral projections in L. insualconae, (3) foot pseudosegment trapezoidal, sub-terminal, never projecting in the new species vs. terminal, near rectangular, scarcely projecting in L. insulaconae, (4) toes smoothly tapering to acute tip in L. zhanjiangensis sp. nov., but with incompletely separated claws in L. insulaconae. Lecane zhanjiangensis sp. nov. also superficially resembles L. yatseni Wei & Xu, 2010, a brackish-water species described from Qi’ao Island in the Pearl River Estuary, Southern China, and recently also recorded from the Nandujiang River Estuary (N19° 59' 25", E110° 23' 34"), Hainan Province, Southern China. The two species have clearly different anterior lorica margins and shapes of toes, however, so can hardly be confused. The record of a previously undescribed Lecane from a freshwater river in Kansas, USA, misidentified as a “small form of L. levistyla (Olofsson) ” (Turner, 1996) (Fig. 2E), bears a striking resemblance to the newly discovered Chinese species. The only morphological differences between specimens from the U.S. and from China are in the relative proportions of lorica plates (dorsal plate relatively shorter in U.S. animals), and slightly shorter toes in the American animals. Such differences may well result from the observer’s perspective, e.g. if seen from a more posteriorly view, or if specimens are not studied in a perfectly horizontal position. We therefore tentatively identify the U.S. specimens as belonging to the same morphospecies, L. zhanjiangensis sp. nov., notwithstanding that different ecology (brackish vs. freshwater) and disjunct distribution across different continents and biogeographical realms make assuming genetically distinct sibling species equally plausible.

Brachionus cf. caudatus var. indica Novotn��-Dvoř��kov��, 1963 (Fig. 4) The specimens found in the littoral zone of Moyangjiang River (Fig. 4A; Tab. 1), and in another three localities in Changde City, Hunan Province, on 16 September 2017 (Fig. 4 B���4E), largely conform to the description of Brachionus caudatus var. indica Novotn��-Dvoř��kov��, 1963, and only differ in minor aspects. The antero-lateral dorsal spines are almost as long as the median spines in specimens from Moyangjiang River and Changde, while they are longer than the median ones in B. caudatus var. indica. Moreover, the ventral median sulcus of the anterior aperture is much deeper in specimens from Moyangjiang River (Fig. 4A) if compared to B. caudatus var. indica and specimens from Changde City (Fig. 4B). Our specimens also show a high similarity with Brachionus caudatus f. majusculus Ahlstrom, 1940 from Florida, from which they differ by ventrally directed posterior spines (Fig. 4E). These are inserted in the same plane as the body axis in B. caudatus f. majusculus. Another similar infraspecific taxon that has been described within the caudatus -complex and that requires attention here is Brachionus caudatus f. apsteini Fadeev, 1925. As in var. indica, posterior spines arise at an angle ventrally in f. apsteini, but are relatively shorter. Previous records of a variant of B. caudatus, sub B. caudatus f. apsteini Fadeev, 1925, as a common taxon in the Southwestern Islands of Japan, show a striking resemblance to our B. cf. caudatus var. indica, and most likely concern the same taxon (Sudzuki, 1992: Plate XII: Figs 2���7). Further specimen material needs to be examined by also including molecular methods to determine the taxonomic status of these supposedly infraspecific taxa within the highly variable morphospecies B. caudatus Barrois & Daday, 1894., Published as part of Wei, Nan, Jersabek, Christian D. & Yang, Yufeng, 2019, Rotifers from China (Western Guangdong Province), with description of Lecane zhanjiangensis sp. nov. (Rotifera: Monogononta: Lecanidae), pp. 66-80 in Zootaxa 4603 (1) on pages 66-80, DOI: 10.11646/zootaxa.4603.1.3, http://zenodo.org/record/2673283, {"references":["Novotna-Dvorakova, M. (1963) Rotatorien des Flusses Yamuna (Indien). Vestnik Ceskoslovenske spolecnosti zoologicke, 27 (3), 170 - 177, pls. 1 - 2.","Sudzuki, M. (1992) Seasonal and local occurrences of the Rotifera in southwestern islands of Japan. Japanese Society of Systematic Zoology, 46, 29 - 70, pls. 1 - 32."]}

Trichocerca marina (Daday, 1890) (Fig. 9) This strictly saltwater species was previously recorded in brackish-water habitats of the Mulanxi River, Fujian Province (Xu, 1998) and on Qi’ao Island in the Pearl River Estuary, Guangdong Province (Wei & Xu, 2014) in China. We found several specimens of this species in the estuarine area of Shimenhe River, Zhanjiang, Guangdong, and here present SEM pictures of its trophi (Fig. 9)., Published as part of Wei, Nan, Jersabek, Christian D. & Yang, Yufeng, 2019, Rotifers from China (Western Guangdong Province), with description of Lecane zhanjiangensis sp. nov. (Rotifera: Monogononta: Lecanidae), pp. 66-80 in Zootaxa 4603 (1) on pages 66-80, DOI: 10.11646/zootaxa.4603.1.3, http://zenodo.org/record/2673283, {"references":["Xu, Y. Q. (1998) A new species and two new records of rotifers from Fujian, China. Acta Hydrobiologica Sinica, 22, 164 - 167. [in Chinese]","Wei, N. & Xu, R. L. (2014) Distinct difference of littoral rotifer community structure in two mangrove wetlands of Qi'ao Island, Pearl River estuary, China. Zoological Studies, 53 (30), 1 - 12. https: // doi. org / 10.1186 / s 40555 - 014 - 0030 - 6"]}

Key to Colurella species recorded in China, modified from De Smet et al. (2015) 1. One toe............................................................................. C. unicauda Eriksen - Two toes, spread or appressed giving impression of single toe.................................................. 2 2. Lorica broad lenticular in lateral view; head aperture margins oblique, strongly directed ventrally; two short spread toes........................................................................................... C. obtusa (Gosse) - Lorica elongate, plump or ovate, not broad lenticular in lateral view; head aperture margins not or only weakly directed ventrally............................................................................................... 3 3. Toes short, toe length/lorica length usually �� 1/4, always separate............................................... 4 - Toes long, toe length/lorica length usually Ż 1/3, spread or appressed............................................. 6 4. Lorica moderately slender; head aperture smaller than greatest lorica height; posterior end of lorica gradually merging into downward curving short projections....................................................... C. uncinata (M��ller) - Lorica moderately slender or plump; head aperture as long as or slightly smaller than greatest lorica height; posterior end of lorica gradually merging into downward curving short or more or less long projections.............................. 5 5. Lorica plump, ending in short, mostly downward curving acute tips.................. C. uncinata bicuspidata (Ehrenberg) - Lorica moderately slender, ending in robust, mostly ventrally directed acute tips........... C. uncinata deflexa (Ehrenberg) 6. Lorica ovate, length/height ��� 1.7; head aperture margins almost rounded, usually highest in median part................ 7 - Lorica moderately slender or elongate, length/height �� 1.7; head aperture margins variable, usually not rounded.......... 9 7. Posterior end of lorica asymmetrical, right side smoothly rounded or with shallow notch, left side tapering to acute tip............................................................................................. C. ovalis sp. nov. - Posterior end of lorica symmetrical....................................................................... 8 8. Foot aperture without dorsal notch; lorica posterior end triangular in lateral view, tongue-shaped in ventral/dorsal view; toes usually appressed............................................. C. sanoamuangae Chittapun, Pholpunthin & Segers - Foot aperture with wide u-shaped dorsal notch; toes spread.................................... Colurella sp. (Fig. 5) 9. Posterior end of lorica tapering to acute angles or tips, occasionally weakly extended or merging into hook-shaped latero-dorsally pointing projections............................................................. C. adriatica Ehrenberg - Posterior end of lorica angular with blunt tip, obtuse or rounded................................................ 10 10. Foot aperture with or without inconspicuous dorsal notch; posterior end of lorica angular with blunt tip................ 11 - Foot aperture with conspicuous dorsal notch or incision, more or less deeply extending dorsally; posterior end of lorica obtuse or rounded.......................................................................................... 12 11. Animal slightly smaller (lorica length 60���82 ��m; toe length 30���38 ��m); lorica usually higher (length/height average 1.59 (1.50���1.85)); ventral sulcus with conspicuous median keel......................................... C. psammophila - Animal slightly larger (lorica length 92 ��m; toes length 42 ��m); lorica relatively lower (length/height 1.87); ventral sulcus without median keel.............................................................. C. cf. psammophila (Fig. 6) 12. Animal usually larger (lorica length 71���110 ��m); head aperture smaller than greatest lorica height; dorsal margin evenly curved; toes usually appressed......................................................... C. colurus (Ehrenberg) - Animal usually smaller (lorica length 50���86 ��m); head aperture almost as long as greatest lorica height; dorsal lorica margin almost straight anteriorly, posterior part strongly curved; toes spread or appressed................................. 13 13. Lorica usually higher (length/height 1.56���1.88); head and foot apertures shallower; toes spread..... C. hindenburgi Steinecke - Lorica usually lower (length/height 1.75���2.15); head and foot apertures deeper; toes spread or appressed...................................................................................................... C. geophila Donner, Published as part of Wei, Nan, Jersabek, Christian D., Xu, Runlin & Yang, Yufeng, 2019, New species and records of Colurella (Rotifera: Lepadellidae) from South China, with a key to Chinese Colurella, pp. 475-490 in Zootaxa 4586 (3) on page 488, DOI: 10.11646/zootaxa.4586.3.5, http://zenodo.org/record/2647236, {"references":["De Smet, W. H., Melone, G., Fontaneto, D. & Leasi, F. (2015) Marine Rotifera. Vol. 50. Calderini, Milano, 252 pp."]}

Colurella sanoamuangae Chittapun, Pholpunthin & Segers, 1999 (Fig. 10) This species was to date only recorded from the Oriental region, in Thale Noi Lake on Malay Peninsula of Thailand (Segers & Pholpunthin, 1997), in coastal peat swamps in the Phuket Province of Thailand (Chittapun et al., 1999; 2007; Segers & Chittapun 2001) and from Northeast India (Sharma & Sharma, 2005; 2014). We found it at three sites on Qi���ao Island (Tab. 1) in low number and at two sites in the Nandujiang River Estuary, Haikou, Hainan Province (sampled biannually, Tab. 1). Colurella sanoamuangae is characterized by the posterior end of the lorica forming a triangular projection (lateral view), that overlays the foot aperture as a tongue-shaped structure (ventral/dorsal view) (Chittapun et al., 1999). This seems to be a stable morphological feature, as far as can be judged from previous observations. Accordingly, a previous record under this name from Iran, with posteriorly rounded lorica (Reihan Reshteh & Rahimian, 2014), probably represents another as yet undescribed species (Jersabek & Leitner, 2013). According to our present knowledge, C. sanoamuangae is an endemic species widely distributed in the Oriental region. Measurements. Body (N = 5 females): lorica length 97.8���101.4 ��m, lorica width 46.7���48.5 ��m, lorica height 59.4���67.2 ��m, anterior aperture width 45.8���48.2 ��m, second foot pseudosegment 6.7���8.1 ��m, third foot pseudosegment 7.9���10.1 ��m, toe length 46.6���47.5 ��m., Published as part of Wei, Nan, Jersabek, Christian D., Xu, Runlin & Yang, Yufeng, 2019, New species and records of Colurella (Rotifera: Lepadellidae) from South China, with a key to Chinese Colurella, pp. 475-490 in Zootaxa 4586 (3) on pages 486-488, DOI: 10.11646/zootaxa.4586.3.5, http://zenodo.org/record/2647236, {"references":["Chittapun, S., Pholpunthin, P. & Segers, H. (1999) Rotifera from peat-swamps in Phuket Province, Thailand, with the description of a new Colurella Bory de St. Vincent. International Review of Hydrobiology, 84, 587 - 593. https: // doi. org / 10.1002 / iroh. 199900052","Segers, H. & Pholpunthin, P. (1997) New and rare Rotifera from Thale-Noi Lake, Pattalang Province, Thailand, with a note on the taxonomy of Cephalodella (Notommatidae). Annales de Limnologie-International Journal of Limnology, 33, 13 - 21. https: // doi. org / 10.1051 / limn / 1997001","Chittapun, S., Pholpunthin, P. & Segers, H. (2007) Diversity of rotifer fauna from five coastal peat swamps on Phuket Island, Southern Thailand. ScienceAsia, 33, 383 - 387. https: // doi. org / 10.2306 / scienceasia 1513 - 1874.2007.33.383","Segers, H. & Chittapun, S. (2001) The interstitial Rotifera of a tropical freshwater peat swamp on Phuket Island, Thailand. Belgian Journal of Zoology, 131, 65 - 71.","Sharma, B. K. & Sharma, S. (2005) Biodiversity of freshwater rotifers (Rotifera, Eurotatoria) from North-Eastern India. Mitteilungen aus dem Museum fur Naturkunde in Berlin-Zoologische Reihe, 81 (1), 81 - 88. https: // doi. org / 10.1002 / mmnz. 200310002","Sharma, B. K. & Sharma, S. (2014) The diversity and distribution of Lepadellidae (Rotifera: Eurotatoria: Monogononta) of India. International Review of Hydrobiology, 99, 1 - 9. https: // doi. org / 10.1002 / iroh. 201401739","Reihan Reshteh, R. & Rahimian, H. (2014) Rotifers of southwest Iran: a faunistic and biogeographical study. Turkish Journal of Zoology, 38, 525 - 537. https: // doi. org / 10.3906 / zoo- 1212 - 16","Jersabek, C. D. & Leitner, M. F. (2013) The Rotifer World Catalog. World Wide Web electronic publication. Available from: http: // www. rotifera. hausdernatur. at / (accessed 10 March 2019)"]}

Colurella psammophila Segers & Chittapun, 2001 (Figs. 7���9) This presumed Oriental endemic was to date only known from the hygropsammon of Mai-Khao peat swamp on Phuket Island, Thailand (Segers & Chittapun, 2001; Chittapun et al., 2007). The present record is the second ever of this species (Wei & Xu, 2014). The specimens found in the Pearl River Estuary (Figs. 7, 8) and in Nandujiang River Estuary (Tab. 1) showed great morphological variability, which mainly resulted in two forms with different lorica shape and fewer transitional specimens (Fig. 8F, 8T). Both forms frequently co-occurred in the samples of the mangrove swamp with all live (Fig. 8 A���8C) and fixed (Fig. 8 D���8T) specimens having a median keel (Figs. 7E, 7F, 8 A���8C, 8K, 8S) in the ventral sulcus, but the two main forms differing in lorica shape as follows: (1) the typical form of the species as originally described (Figs. 7A, 7B, 8 A���8E); (2) lorica ventral margin undulate with conspicuous median bulge and anteroventral lorica margin with shallow concavity or smoothly curved (Figs. 7C, 7D, 8 G���8O). Possibly, this variability was to some extent caused by fixation effects, due to different levels of contraction. We examined numerous trophi of both forms, to confirm conspecificity (Fig. 9). Besides, we found a single specimen with slightly larger and higher lorica and the anterior head aperture margins smoothly curved (dorsally and ventrally straight, medially curved in the original description) (Figs. 7G, 8U), which probably also belongs to Colurella psammophila. This species was collected predominantly from swamps with shallow waters in South China. It was present over many months in mangrove swamps and estuarine habitats in Haikou, Hainan Province, so can be regarded as a eurythermal and euryhaline species (cf. Fontaneto et al., 2006; Fontaneto et al., 2008a). Measurements. Body (N = 15 females): lorica length 70.0��� 81.5 ��m (mean = 74.8�� 3.1 ��m), lorica height 43.0��� 48.9 ��m (mean = 45.9�� 1.9 ��m), lorica width 34.4���38.4 ��m (mean = 36.9�� 1.3 ��m, N = 8), anterior aperture width: 35.0���42.0 ��m (mean = 39.0�� 2.5 ��m), second foot pseudosegment 6.0���8.0 ��m (mean = 6.4�� 0.7 ��m), third foot pseudosegment 7.0���8.0 ��m (mean = 7.4�� 0.5 ��m), toe length 33.0��� 37.7 ��m (mean = 35.0�� 1.3 ��m); lorica length/ height: 1.50���1.68 (mean = 1.59�� 0.07 ��m); third/second foot pseudosegment: 0.88���1.33 ��m (mean = 1.15�� 0.13 ��m). Colurella psammophila (?) specimen (Figs. 7E, 8U). Body (N = 1 female): lorica length 88.7 ��m, lorica height 53.3 ��m, anterior aperture width 46.5 ��m, second foot pseudosegment 6.5 ��m, third foot pseudosegment 7.8 ��m, toe length 40.7 ��m., Published as part of Wei, Nan, Jersabek, Christian D., Xu, Runlin & Yang, Yufeng, 2019, New species and records of Colurella (Rotifera: Lepadellidae) from South China, with a key to Chinese Colurella, pp. 475-490 in Zootaxa 4586 (3) on pages 482-486, DOI: 10.11646/zootaxa.4586.3.5, http://zenodo.org/record/2647236, {"references":["Segers, H. & Chittapun, S. (2001) The interstitial Rotifera of a tropical freshwater peat swamp on Phuket Island, Thailand. Belgian Journal of Zoology, 131, 65 - 71.","Chittapun, S., Pholpunthin, P. & Segers, H. (2007) Diversity of rotifer fauna from five coastal peat swamps on Phuket Island, Southern Thailand. ScienceAsia, 33, 383 - 387. https: // doi. org / 10.2306 / scienceasia 1513 - 1874.2007.33.383","Wei, N. & Xu, R. L. (2014) Distinct difference of littoral rotifer community structure in two mangrove wetlands of Qi'ao Island, Pearl River estuary, China. Zoological Studies, 53 (30), 1 - 12. https: // doi. org / 10.1186 / s 40555 - 014 - 0030 - 6"]}