Dichromadora multisetosa, 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 : 550-554

Dichromadora multisetosa sp. nov.

( Figures 3 , 4 )

Type material

Five males and four females were observed. Holotype: one male, specimen number of new species: LU62 (slide number: LUQ08 I 345) ; paratypes: 14 males 10 females LU63–70 ( LUQ08 I 341,3,6, LUQ08 III 403 ) .

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 after the many long somatic setae all over the body.

Measurements

The measurements are listed in Table 2. Holotype, one male: 86 M 441 516 µm; a = 20, b = 6, c = 6.9, spic = 34, 14, 22, 26, 21. Paratype, one male: 86 V 396 476 µm; a = 16.4, b = 5.5, c = 6, V% = 50%, 14, 26, 29, 21.

Description

Males. Body is cylindrical, blunt at the anterior end and attenuating at the tail end ( Figure 3A,D ); 474–535 µm in length and 23–26 µm in maximum diameter. Cuticle is homogeneous with transverse rows of punctations. There are two longitudinal rows of thick round dots as lateral differentiation that extend from the anterior to the posterior end. Long somatic setae, up to 19 µm are in four sublateral files down the body length.

The head is flattened and has four longer cephalic setae ( Figure 3B ), 10 µm long. Amphids are invisible. There is a large hollow dorsal tooth in the buccal cavity and other teeth are indistinct. Pharynx is about 90 µm in length, with a prominently anterior dorsal bulb and a rounded posterior bulb that is 18 µm in diameter at the widest part. Nerve ring is not clear. The ventral gland is located at the 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 36 µm (1.7 a.b.d.) long, arcuate and slender, distal end tapering ( Figure 3C ). The gubernaculum has a broad dorsocaudal apophysis, about 12 µm long. There are no precloacal supplements. Tail tapers gradually, 3.7 a.b.d. long.

Females. Similar to males. The reproductive system is amphidelphic with reflexed ovaries, anterior branch located to the right of the intestine and posterior one to the left of it. The vulva is simple, at 50% of body length from the anterior end.

Differential diagnosis

Dichromadora multisetosa sp. nov. is characterized by the presence of a clearly anterior dorsal bulb and rounded posterior pharyngeal bulb, long somatic setae and a broad dorsal caudal apophysis of gubernaculum. It is the only species that has gubernaculum with dorsocaudal apophysis in this genus. The species can be distinguished from other Dichromadora species described without precloacal supplements by clearly rounded posterior pharyngeal bulb, long somatic setae and a broad dorsocaudal apophysis of gubernaculum.

Figures

Figure 3. Dichromadora multisetosa sp. nov. (A) lateral view of male body; (B) lateral view of female anterior end, showing buccal cavity, tooth, bulb, lateral punctuation and ventral gland cell; (C) lateral view of male tail end, showing spicule and gubernacular apophysis; (D) lateral view of female body, showing vulva and ovary.

Figure 4. Dichromadora multisetosa sp. nov. (A) lateral view of male body; (B) lateral view of female anterior end, showing dorsal tooth, anterior dorsal bulb and posterior bulb; (C) lateral view of female anterior end, showing somatic setae and ovary.; (D) lateral view of male body, showing spicule and gubernacular apophysis.