Diplopeltoides bulbosus Holovachov & Boström 2017, comb. nov.
Creators: name: Holovachov, Oleksandr
name: Boström, Sven
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Nematoda
Chromadorea
Araeolaimida
Axonolaimidae
Diplopeltoides
Diplopeltoides bulbosus

description: Diplopeltoides bulbosus (Vitiello, 1972) comb. nov.
Figs 5–6, 11A; Table 3
Diagnosis
Diplopeltoides bulbosus is characterised by by a body of 1.12–1.58 mm long; cuticle with longitudinal striation visible only under SEM; cuticularised plate absent; cephalic sensilla papilliform, 1–2 µm long; amphidial fovea an inverted U-shape, 21–28 µm long and 7–11 µm wide, with fine striation; narrow space between amphidial branches not cuticularised; secretory-excretory pore located opposite to basal pharyngeal swelling; tail cylindrical or clavate with bluntly rounded terminus; testes outstretched; spicules 34–50 µm long, strongly curved, with dorsally bent manubrium and subcylindrical, gradually narrowing shaft; gubernaculum plate-like, with or without caudal apophysis.
Material examined
SWEDEN: 3 ♀♀, 2 ♂♂, Skagerrak, 58°19′15.6″–20.9″ N, 10°29′33.5″–34.0″ E, soft bottom 352– 374 m deep, 10 Oct. 2012, “ Inventering Bratten ” leg. (SMNH-159537); 1 ♂, soft bottom 232–240 m deep, Skagerrak, 58°27′36.7″–43.3″ N, 10°32′52.0″–59.4″ E, 12 Oct. 2012, “ Inventering Bratten ” leg. (SMNH-159538); 7 ♀♀ (used for SEM), Skagerrak, 58°22′17.8″–19.4″ N, 10°23′50.8″–24′03.2″ E, soft bottom 351–387 m deep, 10 Oct. 2012, “ Inventering Bratten ” leg.
Description
Adult
Body cylindrical, posteriorly tapering in the tail region, straight or variously curved upon fixation. Cuticle coarsely annulated along entire body, except for smooth anterior end and terminal part of tail; annules 2.5–3 µm wide at mid-body region; longitudinal striation not observed under light microscope, but distinct under scanning electron microscope, covers annules over most of body length, except for anteriormost and posteriormost parts. Somatic setae present along pharyngeal region and on tail. Labial region bluntly rounded. Cuticularised plate underlying cephalic cuticle around amphid absent. Inner and outer labial sensilla not seen. Cephalic sensilla papilliform, equal to 0.1 labial region diameter in length, their bases are located 3.5–6 µm from anterior end. Amphids similar in shape and size between sexes: amphidial fovea an inverted U-shape with ventral branch longer than dorsal branch; tip of ventral branch bent to dorsal side. Interior of amphideal fovea with fine striation visible under light and scanning electron microscopes. Narrow space between amphidial branches (amphidial shield) not cuticularised. Stoma very small, its cuticularised lining uniform with lining of pharynx. Pharynx distinctly subdivided into anterior corpus and posterior postcorpus; corpus cylindrical or slightly fusiform, muscular; postcorpus consists of anterior narrow non-muscular isthmus and pear-shaped glandular basal swelling. Pharyngeal gland nuclei and orifices indistinct. Nerve ring surrounding isthmus. Secretory-excretory system present; secretory-excretory pore located along ventral body line opposite to basal pharyngeal swelling; secretory-excretory duct very short, leading from pore to ampulla; renette cell obscure. Tail cylindrical or clavate, with bluntly rounded terminus. Caudal glands opening via three separate openings, spinneret absent.
Female
Reproductive system didelphic, amphidelphic, reflexed; ovary branches symmetrical. Anterior ovary situated to either right (usually) or left (rarely) of intestine; posterior ovary situated to either left (usually) or right (rarely) of intestine. Vulva pore-like, located posterior to mid-body. Vagina straight, 0.3–0.4 of vulval body diameter, with thick walls and developed sphincter muscle at proximal part; pars
refringens vaginae absent. Intrauterine egg not seen; sperm is visible in uterus. Rectum short, 0.7–0.9 of corresponding body diameter long.
Male
Reproductive system diorchic, both testes outstretched. Spicules paired and symmetrical, strongly curved, with dorsally bent manubrium and subcylindrical, gradually narrowing shaft. Gubernaculum plate-like, with caudal apophysis that is variable in size and can be indistinct in some specimens. Caudal setae present, arranged in subventral and subdorsal rows, but difficult to observe.
Remarks
The recently collected population of D. bulbosus is similar to type specimens in general morphology, measurements and shape of amphids, except for the spicule length. Vitiello (1972) stated in the original description that the spicules are 25 µm long, compared to 45–50 µm in our specimens. Measured from the drawings in the original description, the spicule length of the type specimen appears to be closer to 34 µm.
description: Published as part of Holovachov, Oleksandr & Boström, Sven, 2017, Three new and five known species of Diplopeltoides Gerlach, 1962 (Nematoda, Diplopeltoididae) from Sweden, and a revision of the genus, pp. 1-35 in European Journal of Taxonomy 369 on pages 13-17, DOI: 10.5852/ejt.2017.369, http://zenodo.org/record/3838436