Richtersia coifsoa, Fu & Cai & Boucher & Cao & Wu, 2013

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 : 1926-1930

Richtersia coifsoa sp. nov.

( Figures 4 and 5 ; Table 2)

Type material

Holotype. Adult male (slide 201105521, station 5, coordinates: 21.0553 ◦ N, 108.3442 ◦ E, water depth 30 m, mean particle diameter 6.68 µm, silt-clay 98.02%) collected in June 2006.

Paratypes. One adult male (slide 201105511, station 5) collected in June 2006; one adult male (slide 201106770, 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 and all others collected at station 3, in June 2006 (slides 201103900–914).

Etymology

This work was part of the Chinese offshore investigation funded by the State Oceanic Administration of People’s Republic of China. This species is named for the abbreviation of ‘Chinese offshore investigation funded by the State Oceanic Administration’.

Description

Male. Body very stout (a less than five in males and three in females), cylindrical, truncated anteriorly, tapering posteriorly, largest width at the end of pharynx. Tail short.

Cuticle annulated covered with epizoic microorganisms. The width of annules ranges from 1.5 µm in the cervical region to 2.3 µm in the first half of pharynx region. Every annule carrying spines aligning in 20 longitudinal rows in the anterior part and midbody, and six rows in the posterior part of the body. Arrangement of spines becomes irregular, pointing backward on tail. Annulated cuticule in the anterior two-thirds of tail and smooth cuticule in the posterior third. Spines becoming progressively larger from head region (7.2 µm) towards cloacal region (11.0 µm).

Somatic setae not observed.

Cephalic region with a thick and prominent cuticular collar, carrying six prominent horns, the external circle of setae and the amphideal fovea, which appears as a transversally flattened unispiral structure (100% of corresponding head width).

Six internal labial setae (4–6 µm) situated at the base (inner border) of the labial membrane. The six external labial setae (4–7 µm) and the four cephalic setae (2.8–4 µm) situated on one cuticular ridge, parallel with the cuticular collar.

Labial membrane, with 12 lobes, strengthened by 12 cuticular tubes, forming a pyramidal invagination of the cheilostome wall into the stoma. Stoma rectangular, unarmed with an inner zigzag lining whose posterior half part surrounded by pharyngeal tissue. Undulated anterior border of stoma visible. Pharynx mainly muscular, widened posteriorly and without bulb. Cardia is triangular and small. Intestinal cells containing large and brown granules, bordered by microvilli. Nerve ring not obvious. Ventral gland and pore not visible.

Reproductive system monorchic, testis outstretched, reaching into pharyngeal region, locating ventrally from intestine. Anterior part of vas deferens with granules. Two unequal spicules, both have capitulum, and left spicule twice or three times the length of the right spicule. Gubernaculum double, without apophysis. Three caudal glands present.

Female. Only features differing from those of male are mentioned.

Amphideal fovea, also transversally flattened one turn spiral, but much smaller, width 24–32% of corresponding head width, surrounded by a cuticular annulation.

Intestine overlapping posterior part of pharynx, ventral inner wall of anterior intestine extending into the lumen. More coloured granules of intestinal cells than that in males.

Reproductive system didelphic, amphidelphic. Anterior tract reaching pharyngeal region. Ovaries probably antidromously reflexed.

Diagnosis

Richtersia coifsoa sp. nov. is characterized by its short, stout body with long tail, the regular arrangement of spines into longitudinal rows, the six prominent horns in the cuticular collar, the shape of the amphids (a large flattened unispiral amphids in the male, width 100% of corresponding head diameter; a small transversally flattened unispiral amphids in the female, width about 25% of corresponding head diameter), the long spines and the presence of two unequal spicules with capitulum.

Remarks

Richtersia kreis i Boucher, 1975 and Richtersia heipi Soetaert and Vincx, 1987 have similarly shaped amphids: large flattened spiral in the male and small transversally flattened spiral in the female. The new species R. coifsoa sp. nov. differs by the general shape and length / diameter ratio (a less than three in females and five in males compared with a = 6.2–13.3 and 7.6–9.4 for the two previous mentioned species respectively); the presence of six prominent horns on the cuticular collar; the lower number of longitudinal rows of spines (20 to 6 in the posterior part of the body compared with 32 to 26 in R. kreisi and 30–40 in R. heipi ), and the larger size of body spines; the unequal spicules (much longer left spicule) are as in R. kreisi whereas those of R. heipi have nearly equal left and right spicules.

Figures

Figure 4. Richtersia coifsoa sp. nov. (A) Entire male; (B) apical view at the level of the prisms and invagination; (C) female anterior end.

Figure 5. Richtersia coifsoa sp. nov. (A) Entire female; (B) entire male; (C) male anterior end and with tubules (arrow); (D) female anterior end; (E) female pharynx region; (F) female head and with ‘prism’ (arrow); (G) the six horns on the anterior part of the male head (arrows); (H) the placement of spines on the male body.