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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Cervonema

Cervonema Wieser, 1954 (ref. ID; 3571)

Chromadorida Filipjev, 1929: Family Comesomatidae Filipjev, 1918: Subfamily Sabatieriinae Filipjev, 1934 (ref. ID; 3571)

ref. ID; 3571

Type species

Cervonema allometricum Wieser, 1954 (ref. ID; 3571)
  1. Cervonema allometricum Wieser, 1954 (ref. ID; 3571)
  2. Cervonema gourbaulti Muthumbi, Soetaert & Vincx, 1997 (ref. ID; 1902 original paper)
  3. Cervonema jenseni Gourbault, 1980 (ref. ID; 1902)
  4. Cervonema minutus Muthumbi, Soetaert & Vincx, 1997 (ref. ID; 1902 original paper)
  5. Cervonema tenuicauda Schuurmans Stekhoven, 1950 (ref. ID; 1902)
  6. Cervonema tenuicaudatum (Stekhoven, 1950) Wieser, 1954 (ref. ID; 3571)
    Syn; Linhomoella tenuicaudata Stekhoven, 1950 (ref. ID; 3571)

Cervonema gourbaulti Muthumbi, Soetaert & Vincx, 1997 (ref. ID; 1902 original paper)

Diagnosis

Cervonema gourbaulti sp. n. is characterised by long outer labial and cephalic sensilla that are equal in length (4-5 µm); multispiral amphids with five to six turns; an elongate crenate terminal pharyngeal bulb; a tail with a rather long cylindrical part (3/4 the total length of the tail). C. gourbaulti sp. n. resembles C. jenseni Gourbault, 1980 but can be differentiated from it in the size of the spermatozoa in the testes, which are larger in C. gourbaulti sp. n. compared to C. jenseni; C. jenseni has a gubernaculum and its tail is one third conical and two thirds cylindrical (filiform) and relatively shorter in length (body length divided by tail length=7.5-10.2 compared to body length divided by tail length=3.4-6.3 in C. gourbaulti sp. n. (ref. ID; 1902)

Descriptions

Marine species. (ref. ID; 1902)
  • Female: They are similar to males in general body shape, cuticle, and anterior sensilla. They are however thicker than the males; the maximum diameter at the pharynx is 40-41 µm and the mbd is 39-47 µm. They have smaller (12-13 µm or 60-80% corresponding body diameter) amphids than males. The reproductive system is amphidelphic with outstretched ovaries. Each branch has a short ovary and a large spermatheca filled with sperms. The anterior branch is to the right and the posterior to the left of the intestine. Tail is similar to that of the males (234-460 µm long); and the tail length divided by anal body diameter 7.6-16. (ref. ID; 1902)
  • Male: Body is cylindrical and tapers at both ends. The cervical region is narrow and elongate and the tail is conical with a posterior filiform end. The cuticle has fine striations which start immediately posterior of the cephalic setae. The somatic setae are short, few and scattered. The six inner labial sensilla are indistinct. The six outer labial and four cephalic sensilla are equal (4-5 µm long) in length. The amphids are spiral with 5 turns; and they have a diameter of 13-15 µm (73-88% corresponding body diameter); the anterior border of the amphids is 17-24 µm from the anterior (at least two x head diameter at the level of the cephalic setae from the anterior). The stoma is narrow, unarmed and surrounded by the pharyngeal muscle. Pharynx is cylindrical, 187-240 µm long and slightly expanded at the terminal end to form an elongate crenated bulb, 61-79 µm long by 22-27 µm wide. The dorsal pharyngeal gland opening is at the base of the stoma. The maximum body width at the pharyngeal region is 34-36 µm. The nerve ring is located at 43-48% of the pharyngeal length from the anterior. The opening of the ventral gland is located posterior of the nerve ring at 52-56% of the pharyngeal length from the anterior. The ventral gland is small. Cardia is 8-12 µm long. There are brownish particles enclosed in the intestinal cells which give the intestine a brownish to dark colour appearance. In one female specimens such particles were seen in the lumen of the intestine and the rectum giving the evidence that these particles could be passed from the intestinal cells and excreted to the outside. The reproductive system is diorchic, with opposed and outstretched testes. Each branch has a short germinal zone and the testes are filled with large elongate sperm cells (14-31 µm long). The anterior branch is to the left and the posterior one to the right of the intestine. The spicules are simple with the ventral part being slightly longer than the dorsal part. There are several glandular cells located around the spicules in addition to anterior 5-6 pairs of copulatory ones. The tail is conical (one fifth of the length) and the posterior part is filiform; and measures 206-338 µm long (tail length divided by anal body diameter 7.4-11.3). There are numerous setae at the conical part and fewer on the rest of the tail and two terminal ones. (ref. ID; 1902)

    Etymology

    The species name is given in honour of Dr. Nicole Gourbault of the Museum National d'Histoire naturelle de Paris. (ref. ID; 1902)

    Cervonema minutus Muthumbi, Soetaert & Vincx, 1997 (ref. ID; 1902 original paper)

    Diagnosis

    Cervonema minutus sp. n. is characterised by amphids with 4-5 turns (80-90% corresponding body diameter) and situated at least 3x(head diameter) at the level of the cephalic setae from the anterior; an extremely attenuated anterior end and short simple spicules (0.8 anal body diameter long). C. minutus sp. n. resembles C. macramphis Jensen, 1979, but it can be distinguished from it by the position of the amphid from the anterior (2x(head diameter) at the level of the cephalic setae), the shape and length of the spicules (42-43 µm long) and the presence of the gubernaculum is C. macramphis. C. minutus sp. n. also resembles C. papillatum Jensen, 1988, but it differs from it in the length of the cephalic sensilla (3 µm long), the diameter of the amphid in relation to corresponding body diameter (which is 70% of corresponding body diameter) and its position from anterior (2x(head diameter)). C. minutus sp. n. is further distinguished from C. papillatum by the presence of supplements (6-7) in the latter and the tail shape that is shorter and wider at the cylindrical part. (ref. ID; 1902)

    Descriptions

    Marine species. (ref. ID; 1902)
  • Female: Females are similar to the males in most aspects; general body shape, cuticle, anterior sense organs and tail shape, however, the tail length divided by anal body diameter is larger than in the males (tail length divided by anal body diameter=6.5). The reproductive system is amphidelphic with outstretched ovaries; the ovaries are short and contain a mature ovum in each branch. (ref. ID; 1902)
  • Male: Body is slender and attenuated at both ends; cervical region is elongate and narrow; the tail is long filiform. The cuticle is very finely striated. Somatic setae are few and obvious only on the tail. The anterior sensilla are fine; the inner labial sensilla are indistinct, outer labial and cephalic sensilla are of equal length (2 µm long). The amphids are spiral with 4-5 turns, 8-10 µm in diameter (80-100% corresponding body diameter). The anterior most edge of the amphid is 16-17 µm from the anterior (at least three head diameters). The stoma is very narrow. The pharynx is cylindrical 130-141 µm long, with a slightly expanded terminal bulb, 19-24 µm wide. The nerve ring is located at 57-59% of the pharyngeal length from the anterior. The ampulla of the ventral gland opens posterior of the nerve ring at 65-68% of the length of the pharynx from the anterior. Ventral gland is small. Cardia is small. The reproductive system is diorchic, with opposed and outstretched testes. The anterior branch is to the left and the posterior one to the right of the intestine. The sperm cells are elongate, appear striated. The spicules are short (17-19 µm), flat and in association with several glandular cells. The tail is conical with a filiform end, 110-115 µm long (tail length divided by anal body diameter 4.9-5.2). The caudal glands open through a terminal spinneret. There are three terminal setae. (ref. ID; 1902)

    Etymology

    The species name is derived from the word minute. It is so called because it is smallest Cervonema species recorded. (ref. ID; 1902)

    Cervonema tenuicauda Schuurmans Stekhoven, 1950 (ref. ID; 1902)

    Descriptions

    Marine species. (ref. ID; 1902)
  • Female: They are similar to males in body shape, anterior sensilla, amphids, pharyngeal region and tail. The reproductive system is amphidelphic with outstretched ovaries. The anterior branch is to the left and the posterior one to the right of the intestine. Each branch has a short ovary and either a large spermatheca filled with sperm cells or small one. The vulva and vagina are simple located at 50-55% of the body length from the anterior. (ref. ID; 1902)
  • Male: The body is cylindrical and tapering at both ends. The head measures 7-8 µm in diameter. The cuticle is faintly striated with striations beginning at the anterior border of the amphid. No lateral differentiation. Somatic setae are short and scattered. The anterior sensilla are in two circles; inner labials sensilla are indistinct, the outer labial and the cephalic sensilla are equal in length, 3 µm long (38-50% corresponding body diameter). The amphids are spiral with three to four turns, 6-9 µm in diameter (54-67% corresponding body diameter) and they are located 9-11 µm from the anterior end. The stoma is long (6-8 µm) and narrow and it is surrounded by the pharyngeal tissue on the posterior part. The pharynx is cylindrical, 137-158 µm long and it is expanded posteriorly to form an elongate bulb (30-33% of the pharyngeal length). The nerve ring is located at 44-49% of the pharyngeal length from the anterior. The opening of the ventral gland is situated posterior of the nerve ring at 51-56% of the length of the pharynx. The ventral gland is small and located posterior of the pharyngeal-intestinal junction. The cardia is 8-9 µm long and pear shaped. The reproductive system is diorchic, with opposed and outstretched testes. Anterior branch is to the left and the posterior one is to the right of the intestine. The spematozoa are large elongate to oval shaped and appear striated. The spicules are simple, slightly curved (17-21 µm long) and equal to the anal body diameter. Gubernaculum is absent. There are 6-7 very fine pre-cloacal supplements. The tail is conical with a filiform posterior part (95-110 µm long); the conical part is 35-45% of the tail length (tail length divided by anal body diameter 5.1-6.5). There are three short setae at the tail tip. (ref. ID; 1902)