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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Pternepsilonema

Pternepsilonema Verschelde & Vincx, 1993 (ref. ID; 883 original paper)

ref. ID; 883

Diagnosis

Pternepsilonema gen. n. differs from all other Epsilonematid genera by its large number of subcephalic setae (fourteen to sixteen). Pternepsilonema gen. n. resembles Polkepsilonema gen. n. but can be distinguished of it by location of subcephalic setae (all situated at posterior edge of head capsule in Pternepsilonema gen. n.; eight to ten out of fourteen (to eighteen) setae situated on anterior half of rostrum in Polkepsilonema gen. n.) and by shape of ambulatory setae (straight, heavy setae with double distal tip in Pternepsilonema gen. n. compared to bent, slender setae with single tip in Polkepsilonema gen. n.). (ref. ID; 883)

Descriptions

Body epsilon-shaped. Maximum body diameter 1.4 (males) to 1.6 (females) times minimum body diameter. Ambulatory setae apparently in six (seven) longitudinal rows: in fact existing out of one pair of longitudinal external rows with field of ambulatory setae in between; ambulatory setae straight, broad and hollow, with double distal tip: inconspicuous, straight anterior tip and bent posterior tip. Head capsule with four cephalic and fourteen to sixteen subcephalic setae. Subcephalic setae all situated at, or just in front of, posterior edge of head capsule (i.e. rostrum). Inconspicuous amphid also located at posterior edge of rostrum. Males can have copulatory thorns. Vulva of females located among ambulatory setae. (ref. ID; 883)

Etymology

From Greek: Pterna=heel of a shoe, referring to shape of distal tip of ambulatory setae. (ref. ID; 883)

Type species

Pternepsilonema servaesae (ref. ID; 883)
  1. Pternepsilonema servaesae Verschelde & Vincx, 1993 (ref. ID; 883 original paper)

Pternepsilonema servaesae Verschelde & Vincx, 1993 (ref. ID; 883 original paper)

Diagnosis

Pternepsilonema servaesae gen. et sp. n. is characterized by an inconspicuous pore-shaped amphid; by ornamentation of heavily cuticulized annules; conspicuous, large spines dorsally to dorsolaterally on second half of the body and by broad, straight ambulatory setae with distal double tip. Females and juveniles show firm, hollow supporting setae, not present in males (sexual dimorphism). (ref. ID; 883)

Descriptions

Type species. (ref. ID; 883)
  • Male: Body epsilon-shaped, large (615 µm) with 116 broad annules. Ornamentation (seen by means of light microscope) of deeper layers of cuticle: in pharyngeal region, annules (3-4 µm) have a mosaic of large, differently sized, vacuoles; between dorsal and ventral body curvature, annules (width 3 µm) show a more single row of whimsical vacuoles; posterior to ventral curvature, slimmer annules (1-2 µm) with single row of squared vacuoles; in the anal region, annules (4 µm) ornamented with a mosaic of whimsical vacuoles; posterior tail annules (4.3 µm) show large number of small vacuoles. Cuticle surface ornamented wit ridges. Long somatic setae in pharyngeal region arranged in six longitudinal rows; posterior to ventral curvature in four rows: laterally and subdorsally on both sides of body. Ambulatory setae in six (seven) longitudinal rows; a pair of external subventral rows of eighteen setae with a field of setae in between (depending on annule, two to five setae present between external ones). Ambulatory setae straight, firm and hollow, each ending on a double distal tip: straight inconspicuous anterior tip and bent posterior tip. Ventral (to subventral) field of tiny spines located from dorsal curvature to first ambulatory setae. Five or six pairs of single large copulatory thorns (6 µm) located ventrally between posterior ambulatory setae. Five pairs of short, slim supporting setae following on external rows of ambulatory setae; two last pairs somewhat shifted to ventrolateral compared to first three. Short subventral, somatic setae located on second annule in front of - and first annule behind anus and on last body annule. Dorsal to subdorsal field of long, firm spines, located posterior to ventral curvature, as far as tenth annule in front of tail. Rostrum heavily cuticularized; four cephalic and fourteen to sixteen subcephalic setae (not placed exactly symmetrical). Subcephalic setae all located, together with inconspicuous amphid, at or just in front of posterior edge of the rostrum. Amphidial pore dorsally shifted. Buccal cavity with distinct dorsal and smaller ventral tooth. Pharynx with endbulb; lumen of pharynx shows a curve (although pharynx itself is straight). Nerve ring situated midway between this curve and the endbulb. Small cardia (3 µm). Testis extends to dorsal curvature. Large spermatozoids (length: 14 µm; width: 10 µm) with conspicuous nucleus. Spicules arcuate; club-shaped capitulum; broad velum. Slender gubernaculum. Tail with nine broad annules; non-annulated tailtip heavily cuticularized. Caudal glands extending dorsally above spicules; one spinneret (tailtip) with three separate pores. (ref. ID; 883)
  • Female: Body, annules, ornamentation, pattern of setae as in male; somatic setae of pharyngeal region long and slim. Ambulatory setae in six apparent rows: two external rows (with up to twenty broad, hollow setae) with a field of setae in between. Vulva situated among ambulatory setae. Three firm, hollow supporting setae. Ventrally in this region, three slim somatic setae. One or two pairs of paraanal setae. Ventral field of hairlike spines located between dorsal curvature and first ambulatory setae. Behind ventral curvature and reaching as far as fifth annule in front of tail, dorsal to dorsolateral field of short to very long, heavy spines (measuring up to 28 µm long and 4 µm wide). Head capsule thickly cuticularized; four cephalic setae. Fourteen to sixteen subcephalic setae located, together with pore-shaped amphid, at or just in front of posterior edge of rostrum. Buccal cavity with large dorsal and small ventral tooth. Broad, fringed vulva which rizes above surrounding body annules. Short, bipartite vagina; genital tract didelphic, amphidelphic with reflected ovaries. Tail with six broad annules; non-annulated tailtip thickly cuticularized; caudal glands extending dorsally above rectum, reaching the intestine; spinneret with three separate pores. (ref. ID; 883)
  • Juvenile (third or fourth stage): Body annules slimmer than in adults; ornamentation consisting of single rows of small, whimsical or oval vacuoles; ridges on annule surface more pronounced than in adults: they are prolonged behind posterior edge of every annule resulting in small spines. Ambulatory setae in five rows, external row counting fourteen setae. Two pairs of supporting setae which are similar to those of females. Behind ventral curvature, reaching as far as tail, five or six pairs of very large and firm spines preceded by a pair of small ones. Head capsule with four cephalic and nine subcephalic setae; pore-like amphid. Tail and caudal glands as in males. (ref. ID; 883)

    Etymology

    Named in honour of Rose-Marine De Baerdemaeker-Servaes. (ref. ID; 883)