2 Key Laboratory of Ecology and Biodiversity of Shandong Colleges and University, Liaocheng 252059, China
The genus Sabatieria was established by Rouville based on the type species Sabatieria cettensis in 1903. It is a dominating and large genus in a variety of habitats. To date, 99 valid species have been recorded around the world (Leduc, 2017; Guo et al., 2018; Bezerra et al., 2019). Platt (1985) reviewed the genus and divided 36 valid species into five groups (praedatrix group, armata group, pulchra group, celtica group, and ornata group) according to the main characteristics including the length of cephalic setae, the number of turns of amphideal fovea, the type and distribution of precloacal supplements, features of gubernaculum and apophyses and character of cuticle punctation. Subsequently, Botelho et al. (2014) reviewed the genus in 2014, confirmed 66 valid species, and concurrently described two new species from Brazil: Sabatieria labium and Sabatieria verteris. In the same year, Rosli et al. (2014) also revised the genus, and gave the modified list including 68 valid species that were divided into five groups. Meanwhile, they described a new species Sabatieria dispunctata from New Zealand. The newly recorded species in this genus were Sabatieria megadena Leduc (2017) also from New Zealand and Sabatieria conicoseta Guo, Chang & Yang, 2018 from China.
Sediment samples were collected in many sites from intertidal to sublittoral regions in 2015 and 2016 with the aim to study the biodiversity of free-living marine nematodes in the Jiaozhou Bay of Qingdao, China. The average abundance of the nematodes was 2 538±676 inds./10 cm2. Up to now, 198 nematode species were identified from these habitats (Gao, 2017; Huang et al., 2018, 2019). Sabatieria is the common and abundant genus in the Jiaozhou Bay. Four species of Sabatieria were discovered, and among them, an unrecorded species was identified and is described here as Sabatieria sinica sp. nov.2 MATERIAL AND METHOD
Undisturbed samples of seafloor sediment were taken using a 0.1-m2 improved Gray-O'Hara box corer at a grid of sixteen sampling stations (36°7′10″N–36°35′6″N; 120°14′12″E–120°30′58″E, water depth 3.8–18 m) in July 2016 in the Jiaozhou Bay, Qingdao. The nematodes were collected, sorted, and slide mounted as already indicated in our previous papers (Gao and Huang, 2017; Huang et al., 2018). The descriptions were made from glycerin mounts using a differential interference contrast microscope (Leica DM-2500). Line drawings were made with the aid of a camera lucida. All measurements were obtained using Leica LAS X version 3.3.3, and all curved structures were measured along the arc or median line. Type specimens were deposited in the Key Laboratory of Biodiversity, Liaocheng University, Shandong, China.3 SPECIES DESCRIPTION
Order Araeolaimida de Coninck and Schuurmans Stekhoven, 1933
Family Comesomatidae Filipjev, 1918
Genus Sabatieria De Rouville, 19033.1 Type material
Two males and three females were collected from the Jiaozhou Bay. Holotype, ♂1 on slide number JZW11-4. Paratypes: ♂2, ♀1, ♀2, and ♀3 on the slide number JZW11-2, JZW11-4, and JZW11-3, respectively.3.2 Type locality and habitat
Specimens were collected from the surface 0–2 cm sublittoral silt sediment at station JZW-11 in the Jiaozhou Bay (JZW-11: 36°10′16″N; 120°16′51″E), water depth of 5.5 m.3.3 Etymology
The new species is named after the national name of type locality belonging to, China.3.4 Measurement
All measurement data are given in Table 1.3.5 Description
Males: body cylindrical, attenuated at both ends. Cuticle homogeneous with transverse rows of punctuations from the anterior border of the amphideal fovea to the cylindrical part of tail, and without lateral differentiation of coarse dots. Cervical setae twinning, short, 2.5–3 μm long, three to four pairs. Somatic setae short and sparse. Head slightly set off by constriction posterior to cephalic setae. Inner labial sensilla invisible. Outer labial sensilla papilliform. Four cephalic setae, 3–4.5 μm long. Multi-spiral amphideal fovea with 2.25 turns, 8–9 μm in diameter or 47% of corresponding body diameter. Anterior border of amphideal fovea at the level of cephalic setae. Buccal cavity small, cup-shaped with slightly sclerotized walls. Pharynx cylindrical, with an ovalshaped posterior bulb. Cardia conical. Nerve ring near middle of pharyngeal length, 119–122 μm from the anterior end, 56%–57% of the pharyngeal length. Secretory-excretory system distincte, excretory pore slightly posterior to nerve ring, 141 μm from the anterior end; ampulla large; renette cell large and conspicuous, located posterior to pharyngealintestinal junction.
Reproductive system diorchic, testes opposite and outstretched. Spicules thick with median hollow region, proximal half oval and straight, distal half tapered and curved, with a distinctive constriction or joint between the two halves, 54–69 μm (1.3–1.7 times as long as body diameter at the level with cloaca) long along arcuate. Gubernaculum with a long straight dorso-caudal apophysis, 28–30 μm long. 6–7 papillar precloacal supplements, more or less evenly spaced. Tail 3.2–3.8 body diameter at anus, conico-cylindrical with rounded swollen tip bearing three terminal setae, 6–7 μm long. Cylindrical part about third of total length. A row of ventral caudal setae located at conical portion of tail. Three caudal glands obvious.
Females: similar to males in most morphologicaly aspects excepting tail without ventral caudal setae, amphideal fovea with 2 turns. Reproductive system didelphic with two opposite and outstretched ovaries. Vagina trumpet-shaped, 0.3 times vulval body diameters long. A large sack-like spermatheca situated at each side anterior and posterior to vulva and filled with oval sperms. Vaginal glands present. Vulva with slightly raised lips and situated at about mid-body.3.6 Differential diagnosis and discussion
Sabatieria sinica sp. nov. is characterized by homogeneous cuticle without lateral differentiation; cephalic setae 3–5 μm; spiral amphideal fovea with 2–2.25 turns; thick and arcuate spicules with median hollow region and a mid-constriction or joint; gubernaculum with relatively long dorso-caudal apophyses; 6–7 prominent papillar precloacal supplements. Sabatieria sinica sp. nov. belongs to pulchra group mainly because of the low number of supplements (5–9), the gubernaculum with median pieces, relatively short cephalic setae and short paired cervical setae. Most species in the pulchra group have the amphids with 3–4 turns, but some species such as S. propisinna and S. breviseta have the amphids with only 2.5 and 2.25 turns, respectively. The described species is most close to the pulchra group to comprehensively consider its main characteristics and does not fit under the other groups. The pulchra group currently includes eight species: S. breviseta Stekhoven, 1935; S. maboyae Gourbault & Vincx, 1990; S. mortenseni (Ditlevsen, 1921) Leduc & Wharton, 2008; S. pisinna Vitiello, 1970; S. propisinna Vitiello, 1976; S. pulchra (Schneider, 1906) Tchesunov, 1978; S. pumila Leduc, 2013; S. punctata (Kreis, 1924) Timm, 1952 (Botelho et al., 2014; Rosli et al., 2014).
This new species is most similar to Sabatieria pulchra (Schneider, 1906) Tchesunov, 1978 in morphological features, but differs from the latter species in having thick and jointed spicules (vs slender spicules only enlarged proximal end not constricted at mid in S. pulchra), longer gubernacular apophyses (28–30 μm vs 19–22 μm), slightly shorter cephalic setae (3–5 μm vs 6–7 μm long), and the disposition of precloacal supplements (6–7 papillar precloacal supplements, more or less evenly spaced vs 7–9 tubular precloacal supplements, anterior ones more closely spaced). The difference of Sabatieria sinica sp. nov. with other congeners can be referred to the key below.
Update key to known species of pulchra group
1 Cephalic setae longer than 0.5 head diameter.........2 Cephalic setae shorter than 0.5 head diameter...........3
2 Spicule 2.1 abd, 4–5 precloacal supplements..........................S. maboyae Gourbault & Vincx, 1990 Spicule 1 abd, 6 precloacal supplements........................S. mortenseni Leduc & Wharton, 2008
3 Spicule with distal hook and short distal lamella.................................................S. pumila Leduc, 2013 Spicule without distal hook........................................4
4 Body length shorter than 800 μm............................5 Body length longer than 1 000 μm............................6
5 Cephalic setae 0.22 head diameter, lateral differentiation absent..............S. pissina Vitiello, 1970 Cephalic setae 0.43–0.44 head diameter, lateral differentiation present.......S. propissina Vitiello, 1976
6 Lateral differentiation present, amphideal fovea 3 turns.......................................S. punctata Timm, 1952 Lateral differentiation absent.....................................7
7 Spicule thick with mid constriction, cephalic setae 3–5 μm..............................................S. sinica sp. nov. Spicule slender without mid constriction...................8
8 Body 1.9–2.3 mm, amphids 2.5 turns, cephalic setae 6–7 μm.............................S. pulchra Tchesunov, 1978 Body 1.1–1.3 mm, amphids 3.5 turns, cephalic setae 3–4 μm...........................S. breviseta Stekhoven, 19354 DATA AVAILABILITY STATEMENT
The authors declare that the data supporting the findings of this study are available within the article. The data will be available on request from the corresponding author.5 ACKNOWLEDGMENT
The authors are greatly thankful to Dr. HUANG Mian and Mrs. GAO Qun for their kind help in specimen sorting and slide mounting. We are sincerely grateful to two anonymous referees for reviewing and improving the manuscript.
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