Prochromadorella gracilis, Huang & Wang, 2011

Huang, Y. & Wang, J. Y., 2011, Two new free-living marine nematode species of Chromadoridae (Nematoda: Chromadorida) from the Yellow Sea, China, Journal of Natural History 45 (35 - 36), pp. 2191-2201 : 2196-2200

Prochromadorella gracilis sp. nov.

( Figures 3 , 4 )

Type material

Six males and three females were measured and studied.

Holotype: ♂ 1 on slide LUH083305 ; paratypes: ♂ 2 on slide LUR 081234; ♂ 3, ♀ 2 on slide LUH083302-7 ; ♂ 4 on slide LUH 083302-2 ; ♂ 5, ♂ 6 on slide LUH083302-8 ; ♀ 1, ♀ 3 on slide LUH083302-6 .

Type locality and habitat

Intertidal sandy sediment in the Yellow Sea, from Rizhao coast to Huangdao coast of Shandong province (from 35 ◦ 26’ N, 119 ◦ 34’ E, to 35 ◦ 59’ N, 120 ◦ 10’ E) .

Etymology

This species is named after the shape of body.

Measurements

Measurements are given as follows, see also Table 2.

Holotype ♂ 1

– 155 M 1395 1550 µm; a = 70.5, b = 10.0, c = 9.9, Spic = 22 µm 13212221

Paratype ♀ 1

– 154 V 1310 1495 µm; a = 62.3, b = 9.7, c = 8.0, V% = 46%

14212418

Description

Males. Body slender cylindrical, blunt at the anterior end and attenuating at the tail end ( Figure 3B ). Cuticle heterogeneous with a lateral differentiation only in the anterior pharyngeal region up to half of the pharyngeal length ( Figure 4A,B ). Transverse Notes: de Man a, body length/max. body diameter; a.b.d., anal body diameter; de Man b, body length/pharynx length; de Man c, body length/tail length; c.d., corresponding diameter; V%, position of vulva from anterior end expressed as a percentage of total body length.

rows of three to six large round dots in the cervical region, then smaller, even and elongated ( Figure 4D ).

Amphidial fovea transverse slit-like, 8–10 µm long, located in front of the cephalic setae ( Figure 3C ). Four cephalic setae located at a distance of 6 µm from the anterior end. Labial sensillae papilliform and indistinct. Few short somatic setae scattered along the anterior and posterior regions of the body. Buccal cavity small, conical with one dorsal tooth and two subventral ones usually protruding outside the stoma. Pharynx cylindrical with a slightly swollen posterior end. Nerve ring surrounds the pharynx at 55% of the pharyngeal length from the anterior. Ventral gland located posteriorly of the pharyngo–intestinal junction.

Reproductive system monorchic, with outstretched testis, located to the right of the intestine. Spicules 1.3 a.b.d., arcuate, with a slight swelling at proximal end. Gubernaculum 14 µm long, simple and parallel to the posterior part of the spicules. Five cup-shaped pre-cloacal supplements located from about 18 µm to 80 µm in front of the cloaca and spaced at about 15 µm from each other ( Figure 4D ).

Tail conico-cylindrical with a pointed tip, 7.4 a.b.d. long. Three caudal glands located close to the anterior end of tail.

Females. Similar to males, but the tail is longer than that of males. Reproductive system amphidelphic with two opposed, reflexed ovaries, anterior branch located to the right of the intestine and posterior one to the left of it. Vulva simple and situated slightly pre-median, at 46% of body length from anterior end.

Differential diagnosis

Prochromadorella gracilis sp. nov. is characterized by the combination of the presence of lateral differentiation at the anterior pharyngeal region, small stoma with outstretched teeth, slit-like amphides and five pre-cloacal supplements. The species is similar to Prochromadorella septempapillata Platt, 1973 in the structure and size of body, and differs from the latter in the number of pre-cloacal supplements (five versus seven), smaller stoma and indistinct teeth. This new species is close to Prochromadorella diltlevseni (de Man, 1922) Lorenzen, 1971 in the number (five) of pre-cloacal supplements and the structure of the stoma. The species differs from the latter in the longer body (1114–1637 versus 505–960 µm), longer female tail (10.4 a.b.d. versus 5.2 a.b.d.) and the larger dots as lateral differentiation at the anterior pharyngeal region. Moreover, the new species has a higher value of de Man’s ratio “a” 55.7–70.8 versus 33.6–50 in males and 61.3–65.5 versus 25–40 in females.

Figures

Figure 3. Prochromadorella gracilis sp. nov. (A) Lateral view of male posterior end, showing spicule, gubernaculum and pro-cloacal supplement; (B) lateral view of female body, showing vulva, ovary and sperm packets; (C) lateral view of male anterior end, showing teeth, cephalic seta, amphidial fovea and lateral punctation.

Figure 4. Prochromadorella gracilis sp. nov. (A) Lateral view of male anterior end, showing stoma and lateral punctation; (B) lateral surface view of female anterior end, showing cephalic seta and lateral punctation; (C) lateral view of male anterior end, showing spicule and procloacal supplement; (D) lateral view of male posterior end, showing spicule, gubernaculum and pro-cloacal supplement.