Testudinella zhujiangensis, Wei & Smet & Xu, 2010

Wei, N., Smet, W. & Xu, R., 2010, A New Species Of Testudinella (Rotifera: Testudinellidae) From Qi’Ao Island, Pearl River Estuary, China, Acta Zoologica Academiae Scientiarum Hungaricae 56 (4), pp. 307-315 : 308-312

Testudinella zhujiangensis sp. n.

( Figs 2–4 )

Type locality – An artificial lake of Qi’ao – Dangan provincial mangrove nature reserve on Qi’ao Island (22°26’N, 113°38’E), Zhuhai, Guangdong Province, China .

Holotype – A female in a permanent, glycerine glass slide mount deposited in the Biology Museum of Sun Yat-sen University , Guangdong, China ( ROT00004 ).

Paratypes – Two females in Biology Museum of Sun Yat-sen University (ROT00005, ROT 00006) ; 3 females in the Academy of Natural Sciences of Philadelphia ( ANSP 2074 ) and one in the Royal Belgian Institute of Natural Sciences ( RBINS), Brussels, Belgium (No. IG. 31542, RIR 201) .

Etymology – The name of the new species is derived from Zhujiang, the Chinese name of the

Pearl River , referring to the estuary the type locality is situated in .

Diagnosis – Testudinella zhujiangensis sp. n. is characterized by: a vase-shaped, anteriorly truncated lorica; dorsal anterior margin with broad flat median part and almost straight or weakly undulate lateral parts; ventral anterior margin with shallow median sinus bordered laterally by straight or weakly curved edges; cross-sectional view cruciform with broadly rounded lateral edges; foot opening sub-terminal, a shallow inverted U-shaped slit; distal foot pseudosegment moderately long, penultimate one shorter; unci teeth with lanceolate head; head of major teeth of similar dimension and shape; webbing of minor teeth almost extending up to heads.

Description of female – The lorica ( Fig. 2 ) is vase-shaped, truncate anteriorly, smooth or occasionally very weakly striated ( Fig. 2A ). The ratio lorica length/lorica width is 1.49–1.67 (average 1.57). The dorsal anterior margin shows a broad, flat median part connected by straight or weakly undulate lateral parts. The ventral margin shows a shallow median sinus, bordered laterally by straight ( Fig. 2A, B ) or weakly curved ( Fig. 2C–E ) edges. The dorsal anterior margin not or just reaches ( Fig. 2F ) the ventral margin. The posterior margin is smoothly rounded or very weakly rounded-angular ( Fig. 2F ), or shows an inconspicuous rounded projection ( Fig. 2B ). In cross-sectional view ( Fig. 2G ) the body appears more or less cruciform by the presence of two longitudinal dorsal and ventral furrows, delimiting a protruding median part and broadly rounded lateral edges. The foot opening is sub-terminal, on the ventral side; it takes the shape of a shallow inverted U-shaped slit widening distally. The foot is composed of a long wrinkled proximal part, a short slender penultimate and a longer distal pseudosegment ending in a ciliated cup ( Fig. 2H ). The ratio lorica length/position of antennae relative to the antero-dorsal margin averages 2.30 (2.14–2.57) for the lateral antennae and 3.00 (2.76–3.06) for the dorsal antenna. Two red eyespots.

Trophi malleoramate ( Figs 3 , 4 ). The rami ( Fig. 3A : r) are elongate-triangular with rounded latero-ventral margins, delimiting large latero-ventral fenestrae ( Fig. 3B : rf). The frontal ones of the latero-ventral margins bear a short and blunt, caudally recurved alula ( Fig. 3B : al). Median rami apophyses ( Fig. 3B : ra) are weakly developed. The inner margins of the distal rami sections caudally show 14–16/15–17 (left/right) arched and webbed rami scleropili ( Fig. 3B : as). Basal apophyses form moderately developed ridges, composed of partially fused scleropili ( Fig. 4 : ba). The fulcrum ( Fig. 3A : f) is short and plank-shaped, composed of a double layer of long and longitudinally oriented sclerite bodies, with obvious proximal opening frontally ( Fig. 4 : fo). The unci plates ( Fig. 3A : u) consist of 10–12/9–12 (left/right) weakly curved and strongly webbed teeth. Each uncus has 3, occasionally 4, major teeth with moderately offset lanceolate heads of almost similar dimension. The minor teeth have a lanceolate head bearing two minute lateral knobs at their base; the webbing almost extends up to the base of the heads. The crescent-shaped manubria are composed of a superimposed dorsal, median, ventral and small sub-ventral chamber ( Fig. 3B : dc, mc, vc, svc).

Male and eggs unknown.

Measurements – Lorica length 120–127 µm (mean = 123 µm, N = 10), lorica width 74–82 µm (mean = 78 µm, N = 10), anterior aperture width 49–53 µm (mean = 51 µm, N = 10), penultimate foot pseudosegment 4–5 µm (mean = 4 µm, N = 4), distal foot pseudosegment 14–15 µm (mean = 14, N = 4); trophi (N = 5): length × width 17.0–20.0 × 22.5–26.0 µm, ramus 10.0–12.5 µm, fulcrum 6.0–8.5 µm, largest major tooth 10.0–12.0 µm, manubrium 8.5–12.0 µm.

Distribution and ecology – The species was to date only collected from the littoral plankton of an artificial lake at depths of about 50 cm and distances from the shore of about 2 m, as well as from a mangrove swamp near this lake on Qi’ao sub-ventral chamber, u: uncus, vc: ventral chamber

Island of the Pearl River estuary. Its occurrence was restricted to January and April in the lake, and March, August, September, November and December in the swamp. The highest densities were noted in April for the lake (up to 100 individuals L –1) and December for the swamp (72 individuals L –1). Water depth of the littoral zone of the lake comes to 1 m and the wet depth of the mangrove swamp is about 30 cm. Water temperatures varied from 14–30 °C, salinity varied from 10–22‰.

Figures

Fig. 2. Testudinella zhujiangensis sp.n.: A. Lorica,dorsal view.B–F. Lorica, ventralview.G. Lorica, cross-sectional view. H. Foot pseudosegments. Scale bars: A–G: 50 µm, H: 25 µm

Fig. 3. Testudinella zhujiangensis sp. n., scanning electron microscope photographs of trophi. A. Frontal view. B. Caudal view. Scale bar: 10 µm. al: alula, as: arched scleropili, dc: dorsal chamber, f: fulcrum, m: manubrium, mc: median chamber, r: ramus, ra: ramus apophysis, rf: ramus fenestra, svc:

Fig. 4. Testudinella zhujiangensis sp. n., scanning electron microscope photograph of trophi. Detail of major teeth and proximal part of fulcrum, frontal view. Scale bar: 10 µm. ba: basal apophysis, fo: