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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Paramesonchium

Paramesonchium Hopper, 1967 (ref. ID; 3571)

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

ref. ID; 3571

Type species

Laimella serialis Wieser 1954, designated by Hopper 1967 (ref. ID; 3571)
  1. Paramesonchium belgicum Jensen, 1976 (ref. ID; 1902)
  2. Paramesonchium mombasi Muthumbi, Soetaert & Vincx, 1997 (ref. ID; 1902 original paper)
  3. Paramesonchium seriale (Wieser, 1954) Hopper, 1967 (ref. ID; 3571)
    Syn; Laimella serialis Wieser, 1954 (ref. ID; 3571)
  4. Paramesonchium serialis Wieser, 1954 (ref. ID; 1902)

Paramesonchium mombasi Muthumbi, Soetaert & Vincx, 1997 (ref. ID; 1902 original paper)

Diagnosis

Paramesonchium mombasi sp. n. is characterised by long labial (5 µm) and cephalic (21 µm) setae that are close to each other; cuticle punctated with transversely arranged rows of dots and lateral differentiation of three longitudinal rows of larger dots; amphids are wide (80-90% corresponding body diameter). P. mombasi sp. n. resembles P. belgicum Jensen, 1976 but they can be distinguished from each other by the length of the anterior sensilla; in P. belgicum, cephalic sensilla are longer, 36 µm and labial sensilla are 4 µm long, it is a much thicker nematode (body length divided by maximum body diameter 52-79 compared to body length divided by maximum body diameter 138.4-142.3 in P. mombasi sp. n.); P. belgicum lacks lateral differentiation of longitudinal rows of dots and it has five pre-cloacal supplements which begin far in front of the cloaca. P. mombasi sp. n. also resembles P. serialis Wieser, 1954 but it can be distinguished from it by the shape of the head with the labial sensilla inserted into raised parts of the lips in P. serialis; the length of the anterior sensilla (6 µm for the labial and 32 µm for the cephalic setae); the diameter of the amphid is smaller (13 µm; 70% corresponding body diameter) and the stoma has teeth. P. serialis also has several shorter setae at the pharyngeal region compared to P. mombasi sp. n. (ref. ID; 1902)

Descriptions

Marine species. (ref. ID; 1902)
  • Male: Body is cylindrical and slender, with a blunt head end. The head region shows a kind of a constriction just behind the cephalic setae. The cuticle is annulated and punctated. The punctations are arranged in transverse rows throughout the body. Laterally, there are three longitudinal rows of larger dots that extend from 64 µm away from the anterior until the conical part of the tail. Annules are more pronounced at the pharyngeal and tail regions. Somatic setae were observed only at the cylindrical part of the tail. The anterior sense organs are long; the inner labial sensilla are indistinct, the outer labial sensilla are 5 µm and cephalic sensilla are 21 µm long. There are also four prominent cervical setae (14 µm long) 23 µm from the anterior. The amphids are spiral with 2.75 turns, 9-11 µm in diameter (90% head diameter at the level of the cephalic setae). They are located immediately posterior of the cephalic setae. Stoma is large, cup-shaped, 7-9 µm long with sclerotised walls. Pharyngeal muscles surround part of the stoma. The pharynx is cylindrical, 162-165 µm long and slightly expanded at the terminal end to form the bulb 10 µm wide. The nerve ring surrounds the pharynx at 80-82 µm from the anterior, and the opening of the ventral gland is located posterior of it (103-177 µm from anterior). The ventral gland is located at 46 µm posterior of the pharyngo-intestinal junction. Cardia is long and pear-shaped. The reproductive system is diorchic, with opposed and outstretched testes. Spicules are arcuate, 17 µm long (1.1 and 1.2 anal body diameter). The gubernaculum is short with a dorso-caudally curved gubernacular apophysis 12 µm long. There are six to seven ventral pre-cloacal supplements located close to each other. Posterior of the cloacal, there are three subventral setae at the conical part of the tail. The tail is conico-cylindrical, 90 µm long (tail length divided by anal body diameter 5.6 and 6.4), with a slightly swollen tip. There are two long setae at the tip. (ref. ID; 1902)

    Etymology

    The species is named after the town of Mombasa in Kenya. (ref. ID; 1902)