Trischistoma waiotama, 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 : 12-15

Trischistoma waiotama sp. nov.

( Figs 7 , 8 )

Measurements

Table 2.

Material examined

Holotype: NNCNZ, slide No. 270.

Paratype: twenty six females. NNCNZ, slide Nos 2618–2643 (2618–2627 and 2637–2641 were measured).

Description

General. Body slender, 20–23 μm diameter at mid-region, bent dorsad mainly in the posterior part ( Fig. 7 A). Orthometanemes present. Cuticle very thin, 1–2 μm thick, practically smooth, two separated irregular lines defined by four incisures in each lateral field ( Fig 8 A), beginning at level of cephalic setae, merging at about 3–4 times body diameter anterior to nerve ring and separating again at about 1.5–2 times body diameter posterior to nerve ring, ending near caudal glands. Labial region broadly rounded, slightly offset, separated from neck, 9–11 μm diameter ( Figs 7 B; 8B). Body at posterior end of oesophagus 2.1–2.5 times as wide as head. Inner labial papillae small. Outer labial and cephalic setae in two circles separated longitudinally by nearly the length of a cephalic seta (5–6 μm) ( Figs 7 B; 8B). Inner labial setae 5–7 μm long, cephalic setae 3–5 μm long (about half labial diameter). Ventral cervical seta present, very thin, 90–95 μm from anterior end ( Fig. 7 A & B). Amphid small, calyci- Mouth cavity quite narrow; dorsal teeth minute, anterior tooth at 1.3–1.5 times head diameter from anterior end, posterior tooth at 2.6–2.8 times head diameter from anterior end ( Fig 7 B). Oesophagus cylindrical, strongly muscular, 151–198 μm long. Dorsal pharyngeal gland opening directly into buccal cavity. Cardia small, disc-like. No glands between pharynx and intestine ( Figs 7 C; 8D). Intestine with wide lumen, containing amorphous remains of food. Rectum length less than anal body diameter (10–14 μm vs 15–16 μm). Coelomocytes not seen.

Female. Gonad prodelphic, 142–200 μm long or 17–23% of body length; reflexed, but tip not reaching vulva ( Figs 7 A; 8E). Vulval lips not sclerotized, vagina short, about one third of body diameter. Posterior uterine sac absent. Uterus containing 0– 2 eggs, 62–72 µm long (2.9–3.2 times body diameter) and 16–22 μm diameter ( Fig. 8 E). Vulva-anus distance 1.2–1.6 tail lengths. Tail 50–72 μm long, 6.6–9.1% of total body length, conoid, ventrally bent with straight or dorsally curved tip. Caudal glands three, spinneret small ( Fig. 7 E).

Male. Not known.

Locality and habitat

Holotype and nine paratypes (slide nos 2618–2626) from soil and litter mixture, 0–10 cm depth under a group of native podocarp trees ( Podocarpus spp.), Waiotama , New Zealand (35º 46.641 S, 174º 8.210 E). Coll. Chris Winks, 0 8. iii. 2008; seventeen paratypes (slide nos 2627–2643) from soil and litter mixture, 0–10 cm depth under a native Dacrycarpus dacrydioides tree. Auckland Botanic Garden, South Auckland, New Zealand (37º 0.657 S, 174º 57.491 E). Coll. Zeng Qi Zhao, 23. iv. 2008.

Diagnosis and Relationships

Trischistoma waiotama sp. nov. is characterised by a single ventromedian seta in the cervical region and its short body length ( Fig. 7 B).

Trischistoma waiotama sp. nov. differs from T. otaika sp. nov., T. monohystera , T. equatoriale in having females lacking a postvulval uterine sac and a short body (675–908 μm vs 1215–1326 μm, 1500–2100 μm & 1370–1620 μm, repectively).

Females of T. waiotama sp. nov. are similar to those of T. triregius sp. nov., T. pellucidum , T. tukorehe sp. nov. and T. gracile in lacking a postvulval uterine sac. They can be differentiated from T. tukorehe sp. nov. and T. gracile by having a short body (675–908 μm vs 1088–1149 μm & 1000–1200 μm, respectively); from T. triregius sp. nov. by having a single ventromedian seta vs a pair of setae in the cervical region, and from T. pellucidum by having more posterior vulva (V 79 –83% vs 73–74%).

Based on the SSU and LSU molecular phylogenetic studies ( Figs 3 ; 4), T. waiotama sp. nov. differed from Trischistoma otaika sp. nov. Trischistoma triregius sp. nov. by 0.48% (8 in 1657 bp), 1.51% (25 in 1657 bp) respectively for SSU; and by 6.5% (50 in 768 bp) and 8.1% (62 in 768 bp) repectively for LSU.

Etymology

Waiotama refers to the type locality where the holotype was designated. It is used here as a noun in apposition.

Figures

FIGURE 3 Bayesian tree inferred from SSU gene rDNA sequences. Posterior probabilities exceeding 50 % are given on appropriate clades. Nematode species, GenBank numbers are listed for each taxon.

FIGURE 7 Trischistoma waiotama sp. nov. female. A: Entire body, lateral. B: Pharyngeal region, lateral, showing single ventromedian seta. C: Oesophago-intestinal junction. D: en face view. E: Tail. Scale bars: A, B, C, E = 50 μm; D = 10 μm.

FIGURE 8 Trischistoma waiotama sp. nov. female. A: Pharyngeal region, showing cuticle in the anterior part.: Pharyngeal region, lateral. Arrow indicates amphid. C: Pharyngeal region, showing cuticle in the anterior part. Arrow indicates line in cuticle. D: Oesophago-intestinal junction (arrowed). E: Genital region lateral, eggs arrowed. F: Vulva.