Colurella ovalis, Wei & Jersabek & Xu & Yang, 2019

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, Zootaxa 4586 (3), pp. 475-490 : 476-480

publication ID	https://doi.org/ 10.11646/zootaxa.4586.3.5
publication LSID	lsid:zoobank.org:pub:E7AA11D0-E7E9-4673-820C-8DBA7AC55A5C
persistent identifier	https://treatment.plazi.org/id/2E16BB0D-FF9C-FFF6-FF0D-FB8075CBE1C4
treatment provided by	Plazi
scientific name	Colurella ovalis
status	sp. nov.

Treatment

Colurella ovalis sp. nov.

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Diagnosis. Ovate lorica; head aperture margins dorsally and ventrally smoothly arched, more or less convex medially; posterior end of lorica asymmetric, right side smoothly rounded or with shallow notch, left side tapering to acute tip; foot with three pseudosegments; toes long, usually appressed; trophi malleate; rami robust, triangular without lateral alulae, inner margins straight; basifenestrae triangular, large and deep; basal apophyses plate-shaped with long distal alulae; fulcrum short, triangular, strongly expanded distally; unci plate with 6/6 teeth (right/left), minor dorsal uncini without tooth head; manubria stout, clava strong.

Type locality. Littoral of a mangrove swamp (N22° 25' 42.41", E113° 37' 51.89") in Qi’ao–Dan’gan Provincial Mangrove Nature Reserve on Qi’ao Island, Zhuhai, Guangdong Province, China: depth about 30 cm, distance from shore about 1 m, salinity 6 ‰, water temperature 32 °C, on 30 August 2007.

Holotype. A female in a permanent glycerine glass slide mount deposited in the Museum of Biology , Sun Yatsen University, Guangzhou, China ( SYS _ ROT 00013).

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 00014, SYS_ROT00015); one female in the Museum of Hydrobiological Sciences , Institute of Hydrobiology , Chinese Academy of Sciences , Wuhan , China ( MHBS _R_GD_2019010001); one female in the Academy of Natural Sciences of Drexel University, Philadelphia, USA ( ANSP 2136 View Materials ) .

Etymology. The species name ovalis , a Latin adjective, meaning ovate, refers to the lorica shape of the new species.

Description of female. Lorica smooth, spindle-shaped in dorsal, ovate in lateral view. Average length/height and length/width ratios 1.50 (1.41–1.56) and 2.14 (2.03–2.30), respectively. Head aperture margins smoothly arched dorsally and ventrally, more or less bulged medially in lateral view; dorsally with small V-shaped sinus ( Fig. 2C View FIGURE 2 ), ventrally with deep V-shaped sinus ( Figs. 1E View FIGURE 1 , 2F View FIGURE 2 ). Dorsal margin very slightly curved anteriorly, strongly curved in posterior half, rounded posteriorly ( Figs. 1 View FIGURE 1 A–1D, 2A, 2B, 2D, 2E). Ventral margin smoothly curved. Right posterior end of lorica smoothly rounded ( Figs. 1C View FIGURE 1 , 2D View FIGURE 2 ), occasionally with tiny notch ( Figs. 1A View FIGURE 1 , 2A View FIGURE 2 ). Left posterior end near rectangular with acute tip ( Figs. 1B, 1D View FIGURE 1 , 2B, 2E View FIGURE 2 ). Foot aperture asymmetry evident in dorsal or ventral view, with left lorica extension lateral to the foot ( Figs. 1E View FIGURE 1 , 2C, 2F View FIGURE 2 ). Ventral sulcus very shallow and mostly parallel with ventral margin ( Figs. 1A, 1B View FIGURE 1 ) or almost straight and deeper ( Figs. 1C, 1D View FIGURE 1 ). Foot with three pseudosegments, the third one 1.31 times (1.17–1.52 times) as long as the second one. Toes relatively long, usually appressed, straight to weakly curved.

Trophi malleate ( Fig. 3 View FIGURE 3 ). Rami robust, almost equicrural triangular with blunt margins laterally, left slightly longer than right; cristae rami ( Fig. 3C View FIGURE 3 : cr) on molar surface well-developed, protruded ventrally ( Figs. 3A, 3C, 3D View FIGURE 3 ), decreasing in height toward dorsal; inner margins both anteroposteriorly and dorsoventrally almost straight, rami sclerites well-fused without prominent rami apophyses and teeth; basal chambers and basifenestrae ( Fig. 3B View FIGURE 3 : bf) large and deep, triangular, opened dorsally; basal apophyses ( Figs. 3A, 3C View FIGURE 3 : ba) almost symmetrical, welldeveloped plates with ventrally recurved long distal alulae and caudally opened chambers, composed of a series of fused scleropili. Fulcrum short, near equicrural triangular, strongly expanded distally with median shallow ventral chamber ( Fig. 3A View FIGURE 3 ). Unci plates consist of 6 major uncini ( Fig. 3E View FIGURE 3 : mau), with offset knobbed head and shaft, gradually decreasing in length, and minor dorsal uncini ( Fig. 3E View FIGURE 3 : miu) without teeth and offset head; first major tooth strongly offset with lanceolate head, about 3/10 of total length; subuncus a bundle of slender sclerite bodies ( Figs. 3A, 3D View FIGURE 3 : su); preuncinal tooth ( Figs. 3E, 3C View FIGURE 3 : pt) long with inapparent lanceolate head. Manubria stout, broad, clava strong, cauda weakly curved ventrally, dorsal chamber ( Fig. 3G View FIGURE 3 : dc) a large thin triangular lamella, median chamber ( Fig. 3G View FIGURE 3 : mc) strongly developed with large elongate opening; ventral chamber ( Fig. 3G View FIGURE 3 : vc) triangular with small opening.

Male and eggs unknown.

Measurements. Body (N = 10 females): Lorica length 91.8–95.8 µm (mean = 93.5± 1.4 µm), lorica height

59.0– 65.8 µm (mean = 62.5±2.0 µm); lorica width 40.7–45.3 µm (mean = 43.5± 1.7 µm), second foot pseudosegment 5.8–8.2 µm (mean = 6.9± 0.7 µm), third foot pseudosegment 7.3–10.1 µm (mean = 9.0±1.0 µm), toe length 30.4–37.6 µm (mean = 35.0± 2.3 µm); trophi (N = 5): left ramus length 7.9–8.4 µm (mean = 8.1± 0.2 µm), fulcrum length 2.9–3.3 µm (mean = 3.0± 0.2 µm), fulcrum width 5.3–6.3 µm (mean = 5.9± 0.5 µm), manubrium length 14.0– 14.7 µm (mean = 14.3± 0.3 µm), largest uncus tooth length 6.7–7.8 µm (mean = 7.5± 0.5 µm), left basal plate width 2.9–3.2 µm (mean = 3.0± 0.1 µm).

Distribution and ecology. Distribution and ecological characteristics of the new species are shown in Table 1 View TABLE 1 . To date it was most frequently collected during our monthly sampling of three sites ( Tab. 1 View TABLE 1 ) in Qi’ao–Dan’gan Provincial Mangrove Nature Reserve on Qi’ao Island, Zhuhai, Guangdong Province, China, from January 2007 to December 2010. Only one specimen was found in the middle of the Shizimen water channel, in the natural reserve of Macao mangrove forest ( Tab. 1 View TABLE 1 ) on 9 December 2010.

It was the most dominant species at mangrove swamp sampling sites with very shallow water on Qi'ao Island ( Wei & Xu, 2014; sub Colurella sp. 1), and was present during about half of the sampling months (23/48 months) ( Fig. 4 View FIGURE 4 ), which indicates that Colurella ovalis sp. nov. probably is a eurythermal and euryhaline (cf. Fontaneto et al., 2006; Fontaneto et al., 2008a) interstitial animal.

Comments. The new species shares a superficial morphological similarity with Colurella sinistra Carlin, 1939 . They both have a posteriorly asymmetrical lorica, but can easily be distinguished by size and shape of it. Colurella ovalis sp. nov. is larger with an ovate lorica, and it is also distinct by the shape of the posterior lorica margins. In C. ovalis sp. nov., the left side ends in an acute tip and the right side is smoothly rounded, or occasionally with a shallow notch, whereas in the more elongate C. sinistra it is usually the right side of the lorica that ends in a sharply offset and recurved tip, with the other side forming an obtuse angle ( Carlin, 1939).

With its ovate lorica shape, Colurella ovalis sp. nov. also bears some resemblance to C. sanoamuangae Chittapun, Pholpunthin & Segers, 1999 . It differs by a more rounded lorica, however, with an average length/height ratio of 1.50 (1.41–1.56) and a length/width average of 2.14 (2.03–2.30), compared to about 1.7 and 2.4 in C. sanoamuangae , based on the figures of the original description ( Chittapun et al., 1999) and specimens from Hainan Island ( Tab. 1 View TABLE 1 ); moreover, the lorica is symmetrical in C. sanoamuangae , with a peculiar posterior triangular tip in lateral view, tongue-shaped projection over the foot aperture in ventral or dorsal view. Additionally, the majority of specimens of the new species has a much shallower ventral sulcus than C. sanoamuangae .