Pogaina shenzhenensis Wang & Zhong, 2019

Zhong, Lin-Hong, Xie, Yao-Hang, Hu, Xiao-Zhou, Chen, Yu-Si, Feng, Wei-Tao, Zhang, Yu & Wang, An-Tai, 2019, Two new brackish-water species of Pogaina (Rhabdocoela: Provorticidae) from China, Zootaxa 4679 (2), pp. 353-364 : 356-359

Pogaina shenzhenensis Wang & Zhong n. sp.

( Figs. 3–4 )

Locality. Same as Pogaina sinensis n. sp.

Material examined. Holotype: PLA-Pr011, one whole-mounted specimen. Paratypes: PLA-Pr012, one wholemounted specimen; PLA-Pr013-015, whole-mounted stylet; PLA-Pr016-018, serially-sectioned (sagittal) specimens.

Etymology. Species named after the type locality.

Description. The overall morphology is similar to that of P. sinensis n. sp.. The active adult specimen is 550–750 μm long (ẍ=650 μm; n=3) and 140–160 μm wide (ẍ=150 μm; n=3), with clearly visible zooxanthellae distributed all over the body ( Fig. 3 A–B). The spherical-shaped seminal vesicle (80–100 μm in diameter, ẍ=90 μm; n=3) is located at 33% of the body, and the posterior end connects to the prostate vesicle ( Fig. 3A & C & E , 4 A–B). The prostate vesicle is 75–85 μm long (ẍ=80 μm; n=3) and connects to the stylet posteriorly ( Fig. 3 C & E , 4 A–B). As a whole the stylet (130–140 μm long, ẍ=135 μm; and 30–45 μm wide proximally, ẍ=37 μm; n=3) has the aspect of a N-shaped structure. The distal end continues at one section in a fine band, while the distal rim including the band is provided with dense needle-like sturcture ( Fig. 3 E–J, 4A–C). A copulatory bursa, connected to the common genital atrium, is present. ( Fig. 3D , 4 A–B).

A pair of ellipsoidal ovaries (80–90 μm in length, ẍ=85 μm; n=3) is located at 75% ( Fig. 3A & C–D, 4A–B). Two vitellaria enter the female canal ( Fig. 4 A–B), which is slightly swollen in the middle and is filled with eosinophilic granules. The distal end of the female canal enters the common genital atrium through a short duct surrounded

by sphincter. The seminal receptacle (80–100 μm in diameter, ẍ=90 μm; n=3) is situated anterior to the female ca- nal. It contains large amount of sperm and eosinophilic granules ( Fig. 3A & C–D, 4A–B).

Phylogenetic analyses. The NCBI blast analyses showed that Pogaina shenzhenensis n. sp. is most similar to Pogaina sp. 1 NVS- 2013 in both 18S rDNA (percentage identity: 93.03%; query cover: 98%) and 28S rDNA (percentage identity: 88.96%; query cover: 100%). Similarly, Pogaina sinensis n. sp., is also most similar to Pogaina sp. 1 NVS- 2013 in terms of 18S rDNA (percentage identity: 97.71%; query cover: 99%) and 28S rDNA (percentage identity: 92.57%; query cover: 100%). The concatenated 18S and 28S rDNA genes phylogenetic analyses using Bayesian Inference (BI) and Maximum Likelihood (ML) methods ( Figs 5–6 ) showed that two specimens of P. sinensis n. sp., as well as those of P. shenzhenensis n. sp. clustered together, respectively. Within the genus Pogaina , the two new species P. sinensis n. sp. and P. shenzhenensis n. sp. form a well-supported clade with other species of the genus, including Pogaina sp. 3, Pogaina sp. 2, Pogaina sp. 1 and P. paranygulgus . As such, the molecular data supports the establishment of P. shenzhenensis n. sp. and P. sinensis n. sp. as new species within the genus.

Figures

FIGURE 3. Pogaina shenzhenensis n. sp.: (A–B) live specimen; (C) squeezed live specimen; (D–E) reproductive organs (partim); (F) unfolded stylet; (G–J) different focuses of the stylet.

FIGURE 4. Pogaina shenzhenensis n. sp.: (A) habitus from a live animal; (B) sagittal reconstruction of atrial organs, showing reproductive organs (partim); (C) stylet.

FIGURE 5. The phylogenetic tree inferred from concatenated sequences of 18S and 28S rDNA genes, constructed by Bayesian Inference. Bayesian posterior probabilities are indicated.

FIGURE 6. The phylogenetic tree inferred from concatenated sequences of 18S and 28S rDNA genes, constructed by Maximum Likelihood. Maximum likelihood bootstrap values are indicated.