Dichromadora sinica, Huang & Zhang, 2010

Huang, Y. & Zhang, Z. N., 2010, Three new species of Dichromadora (Nematoda: Chromadorida: Chromadoridae) from the Yellow Sea, China, Journal of Natural History 44 (9 - 10), pp. 545-558 : 554-557

Dichromadora sinica sp. nov.

( Figures 5 , 6 )

Type material

Four males and five females were observed. Holotype: one male, specimen number of new species: LU71 (slide number: LUQ08 I 341) ; paratypes: 14 males, 10 females LU72–79 ( LUQ08 I 342–5, LUQ08 II 384, LUQ08 III 402–3 ) .

Type locality and habitat

Intertidal muddy sediment at Qingdao coast of the Yellow Sea: 36°4′ N, 120°19′ E.

Etymology

This species is named for the country of the type locality, China .

Measurements

The measurements are given in Table 3. Holotype, one male: 136 M 748 850 µm; a = 35.4, b = 6.3, c = 8.3, spic = 30, 20, 23, 24, 23. Paratype: 148 V 744 880 µm; a = 24.4, b = 5.9, c = 6.5, V% = 45% 21, 30, 36, 24.

Description

Males. Body is slender, blunt at the anterior end and attenuating at the tail end ( Figure 5C ); 839–933 µm in length and 24 µm in maximum diameter. Cuticle is homogeneously annulate with transverse rows of punctations, and anterior one or two transverse rows consist of small punctations. There are four longitudinal rows of dots as lateral differentiations that extend from the anterior to the posterior end. The inner two longitudinal rows of dots are thick, and the distance between these dots is about 5 µm at the cervical region and 3 µm at the rest of the body. Somatic setae are sparse and short.

The head is flattened and has four fine and long cephalic setae, up to 22 µm long. Amphids were not seen. The buccal cavity contains a dorsal hollow tooth. Pharynx is 139 µm in length, cylindrical, with an anterior bulb and a posterior well-developed double bulb ( Figure 5A ). Nerve ring was not seen. The ventral gland is large, located at posterior of the pharyngo-intestinal junction. The ventral gland opening was not seen.

The reproductive system is monorchic, with outstretched testis, located to the right of the intestine. The spicules are 29 µm (1.3 a.b.d.), arcuate, tapering and forming a hook at distal end ( Figure 5B ). The gubernaculum is slender and simple, about 18 µm long. There are four (3 + 1) conical precloacal supplements with posterior three more closely spaced (4 µm apart) separated from anterior one (about 20 µm apart). The most posterior supplement was located about 20 µm in front of the cloaca. There is a pair of large subventral double-jointed postcloacal papillae which adjoin cloaca.

Tail is 80 µm (3.7 a.b.d.) long, conico-cylindrical with a clear spinneret. Three caudal glands are located close to the anterior end of tail.

Females. Similar to males. The reproductive system is amphidelphic with reflexed ovaries, anterior branch located to the right of the intestine and posterior branch is to the left of it. The vulva is simple, at 47% of body length from the anterior end.

Differential diagnosis

Dichromadora sinica sp. nov. is characterized by long cephalic setae, presence of clearly anterior pharyngeal bulb and well-developed posterior double bulb, four longitudinal files of dots, spicules with distal hook, four (3 + 1) precloacal supplements and paired subventral double-jointed postcloacal papillae in males. The species is similar to D. quadripapillata Muthumbi and Vincx, 1998 in the character of lateral differentiation and it also resembles D. loisae Muthumbi and Vincx, 1998 , in double pharyngeal bulb. The species differs from the latter two species in the length of cephalic setae, the number and arrangement (3 + 1) of the precloacal supplements, and the presence of double-jointed postcloacal papillae in males.

Figures

Figure 5. Dichromadora sinica sp. nov. (A) lateral view of male anterior end, showing buccal cavity, teeth, cephalic setae, lateral punctuation, double bulb and ventral gland cell; (B) lateral view of male tail end, showing spicule, gubernaculum and four precloacal supplements (C) lateral view of female body, showing vulva and ovary.

Figure 6. Dichromadora sinica sp. nov. (A) lateral view of male anterior end, showing buccal cavity, cephalic setae and lateral punctuation; (B) lateral view of male anterior end, showing double bulb; (C) lateral view of male tail end, showing spicule, gubernaculum and precloacal supplements; (D) lateral view of male tail end, showing spicule and and double-jointed postcloacal papillae.