Dorylaimopsis jinmendaoica Xiao & Guo 2023, sp. nov.

Morphological description of Dorylaimopsis jinmendaoica sp. nov.

urn:lsid:zoobank.org:act: C5A49413-A464-4ABC-8B52-6E7D0B1EB9E7

(Figures 1–2, Table 1)

Type material. Seven males and five females were collected from stations JMJGYH1, JMJGYM1, JMJGYL1 and JMGNTH 1 in February 2021. Holotype: ♂1 on slide number JMJGY20210221 H14. Paratypes: ♂2 on slide number JMJGY20210221 H17, ♂3 on slide number JMJGY20210221 H121, ♂4 on slide number JMJGY20210221 H16, ♂5 on slide number JMJGY20210221 M02, ♂6 on slide number JMJGY20210221 M11, ♂7 on slide number JMGNT20210221 H15, ♀ 1 on slide number JMJGY20210221 H18, ♀ 2 on slide numberJMJGY20210221 H115, ♀ 3 on slide number JMJGY20210221 H130, ♀ 4 on slide number JMJGY20210221 L120 and ♀ 5 on slide number JMJGY20210221 L124.

Type locality and habitat. All specimens were collected from a mangrove (Avicennia marina) forest in Jiangongyu on Jinmen Island. Station JMJGY: 118°18'3.24″E – 118°18'38.52″E, 24°25'12″N – 24°25'38.28″N; Station JMGNT: 118°18'15.84″E, 24°29'9.24″N. The sediment is mainly argillaceous with a small amount of sandy.

Etymology. Species epithet refers to the type locality: Jinmen Island.

Males. Body cylindrical, tapering slightly towards the extremities. Cuticle marked by transverse rows of fine punctations. Lateral differentiation consists of four to five longitudinal rows of larger dots, beginning just posterior to amphidial fovea, extending down almost to base of pharynx and then taking the form of a series of coarse dots in two longitudinal rows terminating in the cloacal area. Lateral differentiation 10–12 µm wide at mid-body, 9–11% cbd. Besides, at tail in four to seven longitudinal rows of dots. Head blunt, slightly isolated from the rest of body. Inner labial sensilla papilliform. Six outer labial sensilla setiform, and four cephalic setae about 3.0–4.9 µm long. Somatic setae scattered and numerous. Amphidial fovea in the shape of a spiral with 2.5–2.75 turns, 9–12 µm wide, and occupying about 41–58% cbd, located immediately posterior to cephalic setae.Anterior portion of buccal cavity cup-shaped, with three triangular teeth. Posterior portion of buccal cavity cylindrical, cuticularized, narrow, 31–33 μm deep and 6 μm wide. Pharynx largely cylindrical with widened base, lacking true bulb, 0.10–0.12 times the length of the body. Nerve ring near the middle of pharynx. Ventral gland cell long-oval shaped, located at the level of anterior end of intestine. Excretory pore anterior to nerve ring. Cardia small, conical and embedded in intestine. Tail length 177–241 µm, conico-cylindrical, with numerous conical setae. Tail tip slightly enlarged. Caudal glands and spinneret present.

Two testes, opposed and outstretched. Anterior testis to the left and posterior testis to the right of the intestine. Spicules length 115–130 µm, paired, equal and arcuated. Proximal end slightly cephalated and with short median cuticularized strip. Ventral apophysis or joint line at middle of spicules absent. Gubernaculum with two caudo-dorsally directed apophysis, rodlike, 28–36 µm long. Approximately 17–21 fibriform precloacal supplements present, not so obvious.

Females. Similar to males in general characteristics. But the tail longer (c 7.6–9.1 vs. c 9.3–12.0). Reproductive system amphidelphic, ovaries outstretched.Anterior ovary to the left and posterior gonad to the right of the intestine. Vulva at 44.0–48.4% of the body length. Short vagina with thick walls perpendicular to the longitudinal body axis.

Dorylaimopsis Jinmendaoica sp. nov. is characterized by head with constriction behind the cephalic setae; the lateral differentiation of longitudinal rows of larger dots which consists of two rows of dots in the middle of body; the amphidial fovea in the shape of a spiral with 2.5–2.75 turns; the buccal cavity cylindrical, with three teeth; spicules equal arcuated; gubernaculum with two caudo-dorsally directed apophyses, rodlike; 17–21 fibriform precloacal supplements present; excretory pore anterior to nerve ring.

Dorylaimopsis Jinmendaoica sp. nov. is most similar to D. variabilis in having the same lateral differentiation pattern of longitudinal rows of dots and the same length of spicules. It differs from the latter species in the length of cephalic setae (3.0–4.9 μm vs. 5.0–9.0 μm) and the number of turns of amphidial fovea (spiral with 2.5–2.75 turns vs. spiral with 2.75–3.0 turns in D. variabilis). It also differs in the location of the excretory pore and the shape of the spicules. The excretory pore anterior to nerve ring in the new species vs. the excretory pore posterior to nerve ring in D. variabilis. Besides, Dorylaimopsis Jinmenislandica sp. nov. is also similar to D. longispicula and D. papilla in having the same lateral differentiation pattern of longitudinal rows of dots. However, there are some differences in other characteristics. Compared to D. longispicula, this new species has a different number of turns of amphidial fovea (spiral with 2.5–2.75 turns vs. spiral with 3.0 turns in D. longispicula) and has a shorter spicule (Spic 115–130 μm vs.179–197 μm in D. longispicula). Compared to D. papilla, this new species has a longer buccal cavity (Bl 28– 33 μm vs. 18–21 μm in D. papilla) and has a longer spicule (Spic 115–130 μm vs.101–107 μm in D. papilla). The ventral glands of D. longispicula and D. papilla both open posteriorly the nerve ring, which is different in the new species (opens before the nerve ring). In this paper, differentiating characteristics of all known male Dorylaimopsis species are given in Table 2 (Ditlevsen, 1919; Cobb, 1920; Chitwood 1936; Timm 1961; Inglis 1961; Inglis 1963; Inglis 1968; Grimaldi & Susanna 1968; Platonova 1971; Jensen 1979; Zhang 1992; Muthumbi et al. 1997; Chen & Vincx 1998; Gagarin & Thanh 2006; Tu et al. 2008; Leduc 2012; Gagarin 2013; Gagarin 2017; Guo et al. 2018; Huang et al. 2018 and Fu et al. 2019).