Mudwigglus patumuka

Leduc, Daniel, 2013, Mudwigglus gen. n. (Nematoda: Diplopeltidae) from the continental slope of New Zealand, with description of three new species and notes on their distribution, Zootaxa 3682 (2), pp. 351-370 : 354-357

Mudwigglus patumuka gen. et sp. n.

( Figs 1–3 , Table 1)

Type specimens. Holotype male, collected on 26 April 2007 ( NIWA cruise TAN0705, station 271), northwestern Chatham Rise (42.622° S, 175.926 E), water depth: 1195 m, sediment depth: 1–5 cm, silt/clay content: 5.8%, CaCO3 content: 79% (NIC 865973). Paratype male, collected on 9 April 2007 ( NIWA cruise TAN0705, station 78), central Chatham Rise (43.979° S, 179.633° E), water depth: 530 m, sediment depth: 1–5 cm, silt/clay content: 32.2%, CaCO3 content: 60%, sediment chlorophyll a concentration: 63 ng /gDW sediment (NIC 865974). One paratype male, collected on 11 October 2001 ( NIWA cruise TAN0116, station U2602D), southern Chatham Rise (46.666 ° S, 178.500° E), water depth: 2800 m, sediment depth: 0–5 cm, silt/clay content: 33.0%, CaCO3 content: 40%, sediment chlorophyll a concentration: 14 ng /gDW sediment (NIC 865975). Three paratype males and one paratype female, collected on 20 February 2011 ( NIWA cruise TAN1103, station 69), central Chatham Rise (43.331° S, 178.288° E), water depth: 350 m, sediment depth: 1–5 cm (NIC 865976). Two paratype females collected on 26 April 2007 ( NIWA cruise TAN0705, station 272), northwestern Chatham Rise (42.627° S, 175.930 E), water depth: 1197 m, sediment depth: 1–5 cm, silt/clay content: 5.8%, CaCO3 content: 79% (NIC 865977).

Etymology. The species name is derived from the Maori words patu muka (= flax pounder), because the tail of this species is of a similar shape (short, blunt, and rounded).

Description. Males. Cylindrical body, colourless, tapering slightly towards the anterior extremity. Cuticle 1 Μm thick, with annuli (i.e., sutures running through the entire cuticle) beginning at level of cephalic setae to near tail tip, situated 2 Μm apart in pharyngeal region and 3 Μm apart in rest of body, no lateral differentiation. Two subventral and two subdorsal rows of short (1 Μm long), sparse somatic setae extending from posterior edge of fovea amphidialis to level of cloaca. Hypodermal gland present, most conspicuous in mid-body region, opening through inconspicuous pore at base of somatic setae ( Figure 1 D, 3B). Lateral chords with honeycomb-like appearance and clusters of small, elongated inclusions always situated ventrally ( Figure 1 D). Two pairs of subventral setae, one pair of subdorsal setae, and three short terminal setae on tail.

Labial region rounded, not set off. Inner labial sensillae not observed. Six minute outer labial sensillae and four cephalic setae, 1–1.5 Μm long. Subcephalic setae absent. Fovea amphidialis an elongated loop, with strongly cuticularised outline, 2.5 times longer than wide. Buccal cavity cup- or funnel-shaped, separated from anterior extremity by narrow, 4–5 Μm long mouth opening surrounded by bulge of inner portion of lip region. Walls of buccal cavity lightly cuticularised. Teeth not observed. Pharynx short, cylindrical, without subdivisions except for oval-shaped basal bulb. Pharyngeal lumen not cuticularised, valvular apparatus absent. Muscular tissue of basal bulb arranged in bundles. Pharyngeal glands and their orifices indistinct. Nerve ring at 60–70% of pharynx length. Secretory-excretory system present, renette cell at level with intestine, ampulla and pore at level of pharyngeal bulb. Pore opening surrounded by small but distinct cuticularised ring. Cardia short.

Reproductive system diorchic with two testes directed anteriorly. Anterior testis outstretched, to the right of intestine, posterior testis antidromously reflexed, situated ventrally. Mature sperm globular to elongated, nucleated, width 5–8 Μm, length 7–10 Μm. Spicules paired, equal, short, arcuate and without capitulum. Spicules evenly cuticularised along entire length, pointed distally. Velum absent. Gubernaculum with straight dorso-caudal apophyses. Rectal gland surrounds distal end of spicules. One pair of large ejaculatory glands situated anteriorly to spicules ( Figure 1 F). Four small tubular pre-cloacal supplements (three in one paratype), one pre-cloacal seta, 1–2 Μm long. Tail short, conical with blunt tip. Three caudal glands each with separate outlet.

Females. Similar to males, but with slightly longer body, smaller fovea amphidialis, and shorter tail. Somatic setae present. Female reproductive system didelphic, amphidelphic with reflexed ovaries. Anterior ovary located to the right of intestine, posterior ovary to the left of intestine. One paratype with both ovaries to the right of intestine. Spermathecae not observed. Vulva located mid-body. Two elongated, granular hypodermal glands situated laterally at level of vulva, pore indistinct ( Figure 2 C). Vagina not at right angle with body surface but directed posteriorly ( Figure 2 B and 3A). Pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships. Mudwigglus patumuka gen. et sp. n. is characterised by its relatively long body (787–945 Μm), strongly cuticularised fovea amphidialis, males with short arcuate spicules and gubernaculum with dorso-caudal apophyses, female with vagina directed posteriorly and elongated hypodermal glands at level of vulva, and short conical tail with blunt tip and three terminal setae. M. patumuka gen. et sp. n. can be differentiated from all other species of the genus based on its relatively large size and presence of short conical tail with blunt tip and three terminal setae (vs conico-cylindrical tail in the other species of the genus).

Figures

FIGURE 1. Mudwigglus patumuka gen. et sp. n. A: Male anterior region; B: male head; C: female head; D: male lateral chord, left hand side view; E: female tail; F: male posterior region. Scale bar = 20 Μm.

FIGURE 2. Mudwigglus patumuka gen. et sp. n. A: Entire male; B: entire female; C: female reproductive system, showing position of elongated lateral hypodermal glands, ventral view. Scale bar: A and B = 45 Μm; C = 25 Μm.

FIGURE 3. Mudwigglus patumuka gen. et sp. n. light micrographs. A: Vulva, left hand side view; B: male lateral chord and hypodermal gland, left hand side view; C: male mid-body region, left hand side view, showing vas deferens (far left), posterior testis (centre), and beginning of anterior testis (far right). Arrow shows position of somatic seta. Scale bar = 20 Μm.