Ptycholaimellus pirus, Huang, Yong & Gao, Qun, 2016

Huang, Yong & Gao, Qun, 2016, Two new species of Chromadoridae (Chromadorida: Nematoda) from the East China Sea, Zootaxa 4144 (1), pp. 89-100 : 91-94

Ptycholaimellus pirus sp. nov.

( Figs 1–2 )

Type material. Five males and two females were measured and studied. Holotype: ♂1 on slide Meio-23(0-2)-2; paratypes: ♂2, ♂3, ♂4, ♂5, ♀1 and ♀2 on the same slide Meio-23(0-2)1–2. Type specimen was deposited in the Qingdao Institute of Oceanology, Chinese Academy of Sciences.

Type locality and habitat. Intertidal silt sediment from the coast of Kangmei Town, Dongshan Island, East China Sea (117°29' E, 23°43' N). Specimens only present in samples of surface layer sediment to a depth of 0–2 cm.

Etymology. Species name refers to the shape of the terminal pharyngeal bulb.

Measurements. Table 1.

Description. Males. Body cylindrical with blunt anterior end and tapered tail end. Cuticle punctated and annulated, six longitudinal rows of horizontal double dots extending from anterior to posterior extremity ( Fig. 2 D). The two lateral longitudinal rows of double dots are larger, about 2 µm apart, and the other longitudinal rows of dots are smaller, about 1 µm apart. Long somatic setae, 11–18 µm long, scattered over body. Anterior end slightly rounded, separated from rest of body by a collar (groove). Amphidial fovea not invisible. Inner and outer labial sensillae inconspicuous; four cephalic setae about one head diameter long. Buccal cavity with a large cuticularized S-shaped hollow dorsal tooth, apical end of tooth hook-like. Pharynx cylindrical with an anterior bulb and a well developed posterior bulb. Anterior bulb asymmetric and larger on the dorsal side; the posterior bulb pear-shaped with an anterior constriction, 25–28 µm long, occupying 26–30% of total pharyngeal length. Cardia not seen. Ventral gland cell located posterior to the terminal pharyngeal bulb, 150 µm from the anterior end, sac-shaped, opens into the collar through a slender duct.. Tail about 4.2 a.b.d. long, elongate conoid, with a short spinneret.

Holotype Paratypes

Characters

♂1 ♂ 2–5 Mean ♀ 1–2 Mean Total body length 698 651–678 667 720–747 734 Maximum body 22 22–25 23.8 32 32 diameter

Head diameter 11 10 10 12–14 13 Reproductive system monorchic with outstretched testis located to right of intestine. Spicules slender, strongly curved, 1.5 a.b.d. long. Gubernaculum plate 11 µm long, parallel to spicules. Precloacal supplements absent.

Females: Similar to males in most respects. Reproductive system amphidelphic with two opposed, reflexed ovaries, anterior ovary located on right and posterior one on left of intestine. Vulva located at about mid body length.

Differential diagnosis and discussion. Ptycholaimellus pirus sp. nov. is characterized by having cuticle with six longitudinal rows of double dots and long somatic setae; relatively long cephalic setae; a pear-shaped terminal pharyngeal bulb occupying less than 30% of pharyngeal length; and an elongate conical tail. The new species differs from other species of this genus by having a short pear-shaped terminal pharyngeal bulb which is less than 30% of total pharyngeal length, and cuticle with six longitudinal rows of horizontal double dots. It resembles Ptycholaimellus jensenii Muthumbi & Vincx 1998 and P. boucheri Jensen & Nehring 1992 in body size and shape. However, it differs from these species by having cuticle with six longitudinal rows of horizontal double dots and long somatic setae (vs cuticle with only two longitudinal rows of lateral horizontal double dots and almost without somatic setae); longer cephalic setae (12–13 µm vs 3–5 µm), smaller ventral gland cell, and a shorter gubernaculum (11 µm vs 14–19 µm). It is similar to P. vincxae Jensen & Nehring 1992 and P. macrodentatus (Timm, 1961) Wieser & Hopper 1967 in the shape of the anterior end and length of cephalic setae. It differs from P. vincxae by the absence of the gubernacular apophysis (vs presence of the apophysis in P. vincxae ) and differs from P. macrodentatus by having cuticle with six vs two lateral longitudinal rows of double dots.

Figures

FIGURE 1. Ptycholaimellus pirus sp. nov. (A) lateral view of the male anterior part; (B) entire view of the female body; (C) lateral view of the male posterior part.

FIGURE 2. Ptycholaimellus pirus sp. nov., micrographs. (A) lateral view of the male body anterior part; (B) lateral view of the female body anterior part; (C) lateral view of the male tail; (D) lateral view of the male body posterior part.