Synonchiella rotundicauda Leduc 2013, sp. nov.
Creators: name: Leduc, Daniel
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Nematoda
Adenophorea
Desmodorida
Selachinematidae
Synonchiella
Synonchiella rotundicauda

description: Synonchiella rotundicauda sp. nov.
Figs 1-3, Table 1
urn:lsid:zoobank.org:act: 2145BDA7-84F7-4DF4-A401-7B706F0C0088
Diagnosis
Synonchiella rotundicauda sp. nov. is characterised by cephalic setae 0.25 cbd long, mandibles each with two pairs of hooks and two wing-like projections laterally, multispiral amphideal fovea with 3.5 turns, eight cup-shaped pre-cloacal supplements, and short tail (2.2. abd) with rounded extremity.
Etymology
The species name is derived from the Latin rotundus (= round, circular) and cauda (= tail), referring to the unusual rounded shape of the tail.
Material examined
Holotype
NEW ZEALAND: ♂, NIWA 88354, 17 Apr. 2007, NIWA cruise TAN0705, station 172, eastern Chatham Rise crest, 43.5162° S, 178.6167° W, 422 m, fine sand (53.5%), silt/clay (23.5%), very fine sand (18.9%).
Paratype
NEW ZEALAND: 1 ♀, NIWA 88355, 15 Nov. 2011, NIWA cruise TAN1116, station 107, northern flank of Chatham Rise, 42.8625° S, 177.9253° E, 467 m.
Description
Male
Body cylindrical, tapering slightly towards anterior extremity. Cuticle ~ 2.0 μm thick throughout body, thicker in tail region, 4 μm, with transverse rows of punctations, without lateral differentiation. Somatic setae short and sparse, in four sublateral rows. Head blunt, rounded, not set off. Six conical inner labial papillae, ~ 1.5 μm long; six longer outer labial setae, 4 μm long, and four cephalic setae, ~ 1 μm long, situated close to or slightly anteriorly to outer labial setae (Fig. 1C). Amphideal fovea cuticularised, multispiral, 3.5 turns. Anterior portion of buccal cavity short and narrow, with inconspicuous rhabdions at anterior extremity. Posterior buccal cavity with three equal mandibles, 15 μm long, with one mandible situated dorsally and two sub-ventrally; each mandible with two pairs of hooks at anterior extremity and two larger wing-like projections emerging laterally and pointing anteriorly; mandible also with small duct apparently connecting anterior extremity of marginal tubes and opening into buccal cavity near anterior end of mandible (Fig. 1G). Posterior buccal cavity surrounded by slightly swollen pharyngeal tissue, pharynx widening posteriorly, not forming true bulb. Several light refractive, golden-brown corpuscules present in pharyngeal region (also present in tail; Fig. 3A, B). Nerve ring at 45% of pharynx length from anterior end. Secretory-excretory (S-E) system present, cellular body of ventral gland small, situated immediatly posterior to pharynx, pore situated ~ 0.5 cbd posterior to nerve ring.
Reproductive system diorchic with outsretched testes. Both anterior and posterior testes on right of intestine. Oval-shaped, nucleated sperm cells, ~ 6 × 7 μm. Spicules paired, strongly curved, 1.8 abd long, widest in middle portion and tapering distally; thin cuticular projection extending from proximal end over almost half of spicule length. Gubernaculum small, plate-like, without lateral pieces, parallel to distal end of spicules. Mid-ventral row of eight cup-shaped pre-cloacal supplements, ~ 4 μm wide and 4 μm deep, situated 6-8 μm apart; distance between supplements increasing slightly anteriorly. Pre-cloacal supplements thickly cuticularised with nerve entering anterior side of cup. No pre-or postcloacal setae or papillae observed. Tail short, with rounded posterior extremity, posterior half with few short setae and ducts, some of which are not connected to setae; terminal setae not observed. Three caudal glands and small spinneret present.
Female
Similar to males, but with smaller amphideal fovea, 2.5 turns. Reproductive system with posterior ovary reflexed, on right of intestine; anterior ovary poorly developed (Fig. 2B). Vulva located at mid-body. Vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.
Remarks
In contrast to Synonchiella rotundicauda sp. nov., all other Synonchiella species are characterised by relatively long, conico-cylindrical tails with a thin cylindrical portion. S. minor is characterised by a relatively short conical tail (2.9 abd), but can be distinguished from S. rotundicauda sp. nov. in having smaller amphid with 1.75 turns (vs. 2.5 turns in S. rotundicauda sp. nov.), longer spicules (200 vs. 51 μm), and more pre-cloacal supplements (42-46 vs. 8).
description: Published as part of Leduc, Daniel, 2013, Two new genera and five new species of Selachinematidae (Nematoda, Chromadorida) from the continental slope of New Zealand, pp. 1-32 in European Journal of Taxonomy 63 on pages 4-9, DOI: 10.5852/ejt.2013.63, http://zenodo.org/record/3823012