Trischistoma tukorehe, Zhao, Zeng Qi, 2011

Zhao, Zeng Qi, 2011, A review of the genus Trischistoma Cobb, 1913 (Nematoda: Enoplida), with descriptions of four new species from New Zealand, Zootaxa 3045, pp. 1-25 : 15-18

Trischistoma tukorehe sp. nov.

( Figs 9 , 10 )

Measurements

Table 2.

Material examined

Holotype: NNCNZ, slide No. 271. Paratypes: ten females. NNCNZ, slide No. 2645–2652.

Descriptions

General. Body slender, 24–27 μm diameter at mid-body, bent dorsad mainly in the posterior part ( Fig. 9 A). Orthometanemes present. Cuticle very thin, 1–2 μm thick, rough surface, two separated lines in lateral field defined by four incisures, irregular, beginning at the level of cephalic setae, merging 2–2.5 times body diameter anterior to nerve ring and separating gradually from about 1–2 times body diameter posterior to nerve ring, and ending near caudal glands. Labial region broadly rounded, slightly offset, separated from neck, 12–16 μm diameter ( Figs 9 A; 10A). Body at posterior end of oesophagus 1.8–2.1 times diameter of head. Inner labial papillae small. Outer labial and cephalic setae in two circles separated by 8–9 μm ( Figs 9 B; 10A). Outer labial setae 6.5–7.4 μm long (about half labial diameter), subcephalic setae 5–6 μm long. Ventral cervical setae absent. Amphid small, calyciform ( Fig. 9 B).

Mouth cavity quite narrow; dorsal teeth prominent, anterior tooth 1.3–1.7 times head diameter from anterior, posterior 2.2–2.6 times head diameter from anterior ( Figs 9 B; 10A). Oesophagus cylindrical, strongly muscular, 251–287 μm long. Dorsal pharyngeal gland opening directly into mouth cavity. Cardia small, disc-like. No glands between pharynx and intestine ( Fig. 10 F). Intestine with wide lumen, containing amorphous remains of food. Rectum about as long as anal body diameter. Coelomocytes not seen.

Female. Gonad prodelphic, 163–220 μm long or 15–19% body length; reflexed, tip not reaching vulva. Distance between posterior end of oesophagus and vulva 1.8–2.1 times longer than oesophagus. Vulval lips slightly sclerotized ( Fig. 10 H), vagina short, less than one third body diameter. Posterior uterine sac absent. Uterus with 0– 1 eggs, each 86–143 µm long (3.3–5.5 times body diameter), 15–21 μm diameter ( Fig. 10 G). Vulva–anus distance 1.9–2.6 tail lengths. Tail 75–92 μm long, 6.8–8.5% of total body length, conoid, ventrally bent with straight or dorsally curved tip ( Figs 9 D; 10J). Caudal glands three, spinneret small.

Male. Not found.

Locality and habitat

Holotype and paratypes collected from litter samples from native forest at Tukorehe Scenic Reserve, near Rotorua, New Zealand (38˚ 0.019 S, 175˚ 53.247 E). Dominant plant species are tawa ( Beilschmiedia tawa , mangeao ( Litsea calicaris ), and rewarewa ( Knightia excelsa ). Coll. Zeng Qi Zhao, 23. xi. 2007.

Diagnosis and Relationships

Trischistoma tukorehe sp. nov. is characterised by having two prominent dorsal teeth ( Fig. 10 A) and relatively long body.

Trischistoma tukorehe sp. nov. differs from T. otaika sp. nov., T. monohystera , T. equatoriale in lack of a postvulval uterine sac in females and short body length (1088–1149 μm vs 1215–1326 μm, 1500–2100 μm & 1370–1620 μm respectively).

Females of T. tukorehe sp. nov. are similar to those of T. triregius sp. nov., T. pellucidum , T. waiotama sp. nov. and T. gracile in lacking a postvulval uterine sac. However, T. triregius sp. nov., T. pellucidum , and T. waiotama sp. nov. have shorter bodies (611–846 μm, 680–850 μm & 675–908 μm vs 1088–1149 μm for T. tukorehe sp. nov.). T. gracile is smaller in diameter (39–47 vs 49– 58), de Man’s Index b (3.8–4.1 vs 4.4–5.3) and morphometric index c ’ (3.9–4.9 vs 4.7–5.9).

Etymology

Tukorehe refers to the type locality. It is used here as a noun in apposition.

Other species

Figures

FIGURE 9 Trischistoma tukorehe sp. nov. female. A: Entire body. B: Pharyngeal region, lateral. C: Genital region, lateral. D: Tail. Scale bars: A, B, C, D = 50 μm.

FIGURE 10 Trischistoma tukorehe sp. nov. female. A: Pharyngeal region, showing outer labial and cephalic setae., Teeth arrowed. B: Pharyngeal region, ventral. Amphid aperture arrowed. C: Pharyngeal region, cuticle in anterior part, lateral. Arrow indicates line in cuticle. D: en face view. E: Nerve ring (arrowed). F: Oesophago-intestinal junction (arrowed). G: Genital region, lateral. H: Vulval region, lateral. I: Vulva, ventral view. J: Tail. K: Anus and caudal glands (arrowed).