CHROMADORIA Pearse, 1942

Fu, Su-Jing, Cai, Li-Zhe, Boucher, Guy, Cao, Jing & Wu, Chen, 2013, Two new Richtersia species from the northern Beibu Gulf, China, Journal of Natural History 47 (29 - 30), pp. 1921-1931 : 1923-1926

Subclass CHROMADORIA Pearse, 1942 Order CHROMADORIDA Filipjev, 1929 Suborder CHROMADORINA Filipjev, 1929 Family SELACHINEMATIDAE Cobb, 1915

Genus Richtersia Steiner, 1916

Richtersia beibuwanensis sp. nov.

( Figures 2 and 3 ; Table 1)

Type material

Four males and four females were measured and studied.

Holotype. Adult male (slide 201103632, station 3, coordinates: 20.6505 ◦ N, 108.0381 ◦ E, water depth 41 m, mean particle diameter 8.7 µm, silt-clay 67.64%), collected in June 2006.

Paratypes. Two adult males (slide 201106771, station 6, coordinates: 20.6488 ◦ N, 108.6226 ◦ E, water depth 43 m, mean particle diameter 7.612 µm, silt-clay 92.60%), collected in October 2007; one adult male (slide 201103600, station 3), collected in April 2007; four adult females (slide 201103632, 201103900-902, station 3), collected in June 2006.

Etymology

This species is named for the sampling place Beibu Gulf.

Description

Male. Body short, cylindrical, rounded anteriorly, tapering posteriorly, largest width in mid-body region, tail short.

Cuticle annulated, the width of annules is about 1 µm. Each annule carrying numerous short, stout spines pointing backward anteriorly, becoming gradually larger from head region toward cloacal region. These spines arranged in regular longitudinal rows from the end of pharynx. At the end of pharynx about 32 rows, in mid-body region about 28 rows, at level of cloaca about 10 rows. Posterior one-third of tail carrying no spines. Two-thirds of tail with regular annules, and one-third of tail-tip smooth.

Somatic setae (about 3 µm) arranged in eight rows.

The six internal labial setae (about 6 µm) are situated on a hyaline labial membrane. The six external labial setae (about 6 µm) and the four cephalic setae (about 4 µm) are almost at the same level.

Amphideal fovea, surrounded by spines, large with width 50–70% of corresponding head diameter, round and ventrally wound spiral, three and a half turns, located about 8.8 µm from anterior end.

Labial membrane, with 12 lobes, strengthened by 12 cuticular tubes, forming a pyramidal invagination of the cheilostome wall into the stoma. Invagination with 12 lobes, alternating with 12 triangular prisms. Stoma triangular, unarmed and partly surrounded by pharyngeal tissue. Pharynx cylindrical with crenated wall and without bulb. Cardia is triangular and prominent. Intestine a simple tube with cells containing brown granules, more abundant in the anterior part of intestine, evenly placed in the other parts and bordered by microvilli. Nerve ring not observed. Ventral gland and pore not observed.

Reproductive system monorchic, with outstretched testis, lying ventrally from intestine, reaching into pharyngeal region. Vas deferens arranged in transverse bands, with small granules. Two unequal spicules, left spicule (98.2 µm) about twice as long as right spicule (44.0 µm). Right spicule has a capitulum. Gubernaculum (24.9 µm) double, an inverted L-shaped, with an anterior apophysis on each side. Tail short, three caudal glands of the same length.

Females. Only features different from those of male are mentioned. More clumsy than male. Amphideal fovea, smaller, width about 36% of corresponding head diameter, ventrally wound spiral, one turn, surrounded by cuticular annulation. Reproductive system didelphic, amphidelphic. Ovaries reflexed.

Diagnosis

Richtersia beibuwanensis sp. nov is characterized by the presence of multispiral amphids in the male (3.5 turns, width 50–70% of corresponding head diameter) and unispiral amphids in the female (about 36%). In the cervical region, the short spines are numerous and irregular, and from the mid-body region, the spines are regular. There are two unequal spicules. Furthermore, the gubernaculum has anterior apophyses.

Remarks

In Richtersia beibuwanensis sp. nov., the pattern of the spines in the anterior region, the shape of the amphids of males and females are similar to those of Richtersia staresensis Soetaert and Vincx, 1987 and Richtersia coomansi Soetaert and Vincx, 1987 . However, the new species is stouter than the latter two (mean a = 7.1 in males, 5.8 in females compared with values between 10 and 18 in the two other species). The multispiral amphids of the male is round with 3.5 turns whereas it is more flattened with respectively 3 and 5.25 turns in R. staresensis and R. coomansi . Both right and left spicules (51 and 108 µm) in R. beibuwanensis sp. nov. are longer than that in R. staresensis (41 and 93 µm), shorter than R. coomansi (66–80 and 124–143 µm), but the ratio of left and right spicules of all is similar. Furthermore, there is a ‘hairy’ tail in the female of R. coomansi that the other two species do not have.

Figures

Figure 2. Richtersia beibuwanensis sp. nov. (A) Entire male; (B) female anterior end.

Figure 3. Richtersia beibuwanensis sp. nov. (A) Entire male; (B) male anterior end; (C) female anterior end; (D) rows of cuticular spines at mid-body region.