Gieysztoria shantouensis Zhang, Li & Wang, 2014

Zhang, Hang, Li, Yi-Kui, Wu, Cheng-Chen & Wang, An-Tai, 2014, Two new species of the genus Gieysztoria (Rhabdocoela: Dalyelliidae) from China, Zoological Systematics 39 (4), pp. 485-495 : 486-488

3.1 Gieysztoria shantouensis Zhang, Li & Wang , sp. nov. ( Figs 1–8 )

Material examined. Holotype PLA-G0060 , ditches in Chengtian , Chaonan, Shantou, Guangdong (23°10'57"N, 116°28'18"E) ( Fig. 17 ) , 21 January 2013, coll. Yi-Kui Li. saved in Bouin’s solution and stained by H.E. method. Paratypes. PLA-G0061 – PLA-G0066 , same data as holotype ( PLA-G0061 – PLA-G0063 , the whole specimens; PLA-G0064 –PLA- G0066, isolated sclerotic stylets). All materials were deposited in National Zoological Museum , Institute of Zoology, Chinese Academy of Sciences ( IZCAS), Beijing, China .

Description. Live individual about 1 005–1 340 μ m long, and middle part of bodies up to 280–350 μ m wide. Anterior part of body bluntly rounded, posterior part tapered. Whole body appears spindle-like. Salmon pink pigments distribute under epidermis ( Fig. 1 ). Two reniform eyes locate at back of forebrain near pharynx, space between them about 72 μ m. Barrel-shaped pharynx 170 μ m long and 160 μ m wide. Pocket-like intestinal canal connects to pharynx, with distinct glands in junction ( Figs 1–2, 5–6 ).

Reproductive system. Hermaphrodite, with one gonopore. Female reproductive system consists of an ovary, oviducts, uterus, receptaculum seminis, vitellaria, bursa copulatrix, genital atrium and common gonopore. Strip-shaped ovary lies at back of posterior intestine. Oviducts from rear of ovary lead to uterus near rump. Branches of oviducts lead to spherical receptaculum seminis which contains serried sperms. An orange-yellow elliptic egg, with 190 μ m long and 96 μ m wide, often appears inside uterus, both ends of it slightly sharp ( Fig. 3 ). Two vitellaria extend dorsolaterally, with 380 μ m long. Each vitellarium with numerous finger-shaped branches. Vitelloducts from left and right join together at back of intestines, then lead to uteru, and other side of it connects genital atrium. Finger-shaped bursa copulatrix comprises myofibers, and opens into genital atrium through a pore ( Figs 5–6 ).

Male reproductive system consists of testes, vas deferens, a vesicula seminalis, a vesicula granulorum, prostate tissues and a sclerotic stylet. Paired oval-shaped testes situated laterally at posterior intestine, with a vas deferens at backend of each testis extending to vesicula seminalis. Double-ball-shaped vesicula seminalis contains serried sperms, covered by a muscular layer. Behind it lies a cylindrical-shaped vesicula granulorum, which comprises eosinophilic granules inside, outside lies prostate cells. Sclerotic stylet, with total length 137 μ m, connecting to backend of vesicula granulorum, consists of a closed girdle and 7 spines. Girdle formed by sclerotic collagenous fibers, with height 44 μ m, diameter 70 μ m. Base of each spine connected to a U-shaped muscular layer. Lateral spines appear dagger-shaped, middle ones cynodontshaped. Spines differ in length, shortening from both sides to middle gradually. Outer spine 94 μ m long, and the middle 59 μ m long ( Figs 4–7 ). Stylet of immature individual is not fully sclerotized, with some unsclerotized collagenous fibers around girdle ( Fig. 8 ).

Etymology. The specific name refers to the type locality, Shantou City, Guangdong Province, China.

Discussion. Sclerotic stylet is the critical taxonomic character to identify species of genus Gieysztoria . The genus Gieysztoria is divided into two groups, Aequales and Inaequales ( Luther, 1955). The stylet of Aequales usually contains a proximal girdle and lateral spines which are similar in size and shape. Species of Inaequales have complicated stylets, and are divided into four subgroups: Fenestratae, Radiatae, Aberrantes, Falcatae ( Luther, 1955; Damborenea et al., 2005; Van Steenkiste et al., 2012). The proximal girdle of Fenestratae has one or more pores; Radiatae does not have pores, and has actinomorphic stylet; Aberrantes has the stylet irregular ( Luther, 1955; Damborenea et al., 2005). The stylet of the Falcatae is a small thick hook-like spine, which is similar to a raptor’s claw ( Van Steenkiste et al., 2012). By comparing, the new species belongs to Gieysztoria, Inaequales, Aberrantes.

Nine species, G. shantouensis Zhang, Li & Wang , sp. nov., G. oligocentra ( Steinböck, 1948) , G. papii ( Young, 1977) , G. pseudodiadema (Noreña-Janssen, 1995) , G. shenzhensis (Wang & Wu, 2005b) , G. pulchra (Wang & Deng, 2006) , G. macrovariata ( Weise, 1942) , G. macrovariata 9-spinosa ( Luther, 1955), G. octospinosa ( Luther, 1955) are similar because of the number of the terminal spines of stylet. Among them, the stylet of G. oligocentra , G. papii and G. pseudodiadema have 8, 6 and 8 spines, respectively. However, G. oligocentra and G. papii belongs to Aequales, and G. pseudodiadema and the new species belong to Inaequales. The stylet of G. pseudodiadema is 60–70 μ m long, and the spines are 42 μ m long. The shape of stylet between G. pseudodiadema and the new species is significantly different. And the length of stylet of the new species is 2 times as long as G. pseudodiadema ( Luther, 1955; Damborenea et al., 2005). G. shenzhensis has 8 spines within its stylet, with 4 thick and 4 flagellous spines, actinomorphic, belongs to Radiatae, a subgroup of Inaequales ( Luther, 1955), which is significant different with the new species. G. pulchra , G. macrovariata and G. macrovariata 9-spinosa belong to the same subgroup with the new species ( Luther, 1955). They have 13, 10 and 9 spines within their stylets, respectively, while the new species has 7 spines within its stylet. The stylet of G. octospinosa is the most similar to the new species. However, its stylet is 55 μ m in length, has 8 sclerotic spines, and spines in the middle are longer than those in the lateral. The stylet of the new species is 137 μ m long in total, has 8 spines, and spines in the middle are shorter than those in the lateral.

Figures

Figs 1–5. Gieysztoria shantouensis Zhang, Li & Wang, sp. nov. 1–2. Alive individual. 3. Egg. 4. Stylets. 5. Whole specimen. Scale bars: 1–2=200 μm, 3–4 =50μm, 5 =100μm.

Figs 6–8. Gieysztoria shantouensis Zhang, Li & Wang, sp. nov. 6. Ventral view. 7. Stylets. 8. Unbaked stylets. Scale bars: 6=100 μm, 7–8=50 μm.

Fig. 17. Distribution of Gieysztoria spp.