Diplopeltoides suecicus, Holovachov & Boström, 2017

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, European Journal of Taxonomy 369, pp. 1-35 : 5-10

publication ID

https://doi.org/ 10.5852/ejt.2017.369

publication LSID

lsid:zoobank.org:pub:67FB160D-14E1-4970-8190-4F927DDC4DC4

DOI

https://doi.org/10.5281/zenodo.3852352

persistent identifier

https://treatment.plazi.org/id/BD6CBB55-4DF6-4E17-802B-093C3DE95BD5

taxon LSID

lsid:zoobank.org:act:BD6CBB55-4DF6-4E17-802B-093C3DE95BD5

treatment provided by

Carolina

scientific name

Diplopeltoides suecicus
status

sp. nov.

Diplopeltoides suecicus sp. nov.

urn:lsid:zoobank.org:act:BD6CBB55-4DF6-4E17-802B-093C3DE95BD5

Figs 1–3 View Fig View Fig View Fig ; Table 1 View Table 1

Diagnosis

Diplopeltoides suecicus sp. nov. is characterised by a body of 0.82–1.02 mm long; cuticle with longitudinal striation visible only under SEM; cuticularised plate underlying cephalic cuticle around amphid present; cephalic sensilla setiform, 4–6 µm long; amphidial fovea an inverted U-shape, 14– 21 µm long and 6–9 µm wide; wide space between amphidial branches areolated; secretory-excretory pore located opposite to basal pharyngeal swelling; tail subcylindrical with bluntly rounded terminus; testes outstretched; spicules 27–31 µm long, strongly curved, with weakly defined manubrium and subcylindrical shaft; gubernaculum plate-like, with caudal apophyses.

Etymology

The specific epithet “ suecicus ” (masculine) – Swedish, refers to the country where the new species was first discovered.

Type material

Holotype

SWEDEN: ♂, Gullmarn Fjord near Fiskebäckskil, 58°15′25″ N, 11°27′30″ E, soft mud from 30 m deep, 11 Aug. 2011, O. Holovachov leg. ( SMNH Type-8840 ).

GoogleMaps

Paratypes

SWEDEN: 4 ♀♀, 1 ♂, Gullmarn Fjord near Fiskebäckskil, 58°15′25″ N, 11°27′30″ E, soft mud from 30 m deep, 11 Aug. 2011, O. Holovachov leg. ( SMNH Type-8841); 1 ♀, 2 ♂♂, Gullmarn Fjord near Fiskebäckskil, 58°15′37″ N, 11°27′43″ E, soft mud from 44 m, 11 Aug. 2011, O. Holovachov leg. ( SMNH Type-8842).

Description

Adult

Body cylindrical, posteriorly tapering in the tail region, straight or weakly ventrally curved upon fixation. Cuticle coarsely annulated along entire body, except for visually smooth anterior end (faint annulation is visible under the scanning electron microscope) and terminal part of the tail; annules 1.5–2.5 µm wide at mid-body region; longitudinal striation not observed under the light microscope but distinct under the scanning electron microscope, covers annules over entire body length. Somatic setae visible on tail. Labial region bluntly rounded, lips fused. Cuticularised plate underlying cephalic cuticle around amphid, extending from the level of the anteriormost edge of amphid to the posteriormost edge of amphid, 17– 21.5 µm long and 12–14.5 µm wide at its base; cuticular plates are connected with each other on ventral and on dorsal sides. Inner labial sensilla not seen; outer labial sensilla small papilliform, located on the anterior surface of lips. Cephalic sensilla setiform, equal to 0.5–0.8 labial region diameters in length, their bases are located 1.5–2 µm from anterior end. Amphids similar in shape and size between sexes: amphidial fovea an inverted U-shape with its dorsal branch longer than ventral branch. Wide space between amphidial branches (amphidial shield) strongly cuticularised and areolated. Stoma very small, its cuticularised lining is uniform with the lining of the 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 the ventral body line opposite to basal pharyngeal swelling; secretory-excretory duct very short, leading from pore to ampulla; renette cell small, its body adjacent and ventral to anterior part of intestine. Tail subcylindrical 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 or left of intestine; posterior ovary situated to either right or left of intestine. Vulva pore-like, located at or immediately posterior to mid-body. Vagina straight, 0.2–0.3 of the vulval body diameter, with developed sphincter muscle at its proximal part; pars refringens vaginae absent. Intrauterine egg not seen; sperm is often present in the uterus. Rectum short, 0.7–0.9 of the corresponding body diameter long.

Male

Reproductive system diorchic, both testes outstretched. Spicules paired and symmetrical, strongly curved, with weakly defined manubrium and subcylindrical shaft. Gubernaculum plate-like, with a pair of strong closely set caudal apophyses. Caudal setae present, arranged in subventral and subdorsal rows, but difficult to observe and count.

Remarks

Diplopeltoides suecicus sp. nov. is most similar to D. axayacatli and D. grandis sp. nov. in having strongly developed cuticularised plate and amphid with wide and ornamented interamphideal shield. The new species differs from D. axayacatli in the shape of the amphid (loop-shaped vs hook-shaped in D. axayacatli ), shorter cephalic setae (4–6 µm vs 15–20 µm in D. axayacatli ), gubernaculum with strong apophyses (vs without apophyses in D. axayacatli ) and shorter tail (c’ = 2.8–3.7 vs 5.0–6.0 in D. axayacatli ); it differs from D. grandis sp. nov. in shorter body (0.82–1.02 mm vs 2.06 mm in D. grandis sp. nov.) and shorter cephalic setae (4–6 µm vs 18.5 µm in D. grandis sp. nov.).

Table 1. Measurements (in µm) of Diplopeltoides suecicus sp. nov., presented as mean and (range).

Sex Holotype male Female Male
Number of specimens 1 5 4
Body length 932 896 (821–980) 963 (932–1018)
Body diameter (BD) 23 32 (30–33) 22 (19–24)
Pharynx length 87 87 (81–92) 88 (87–90)
Tail length 67 60 (57–67) 73 (67–83)
Anal body diameter (ABD) 19 20 (18–21) 21 (19–23)
a 40.9 28.1 (24.8–33.1) 44.8 (39.1–49.8)
b 10.8 10.3 (9.6–10.9) 10.9 (10.4–11.3)
c 13.8 14.9 (14.2–15.9) 13.2 (12.2–13.9)
c’ 3.5 3.1 (2.8–3.4) 3.6 (3.5–3.7)
V or T (%) 52.0 52.9 (50.0–55.3) 73.0 (52.0–92.8)
Labial region diameter 8.0 8.6 (8.0–9.0) 8.1 (7.5–8.0)
Cephalic setae length 6.0 5.0 (4.0–6.0) 5.7 (5.5–6.0)
Amphid from anterior end 7.5 5.8 (5.5–6.0) 6.7 (5.5–7.5)
Dorsal amphid branch length 17.0 15.5 (14.0–16.5) 17.9 (15.0–21.0)
Ventral amphid branch length 15.0 14.5 (13.0–17.0) 17.1 (15.0–19.0)
Amphid width 8.0 6.6 (6.0–7.0) 7.8 (6.0–9.0)
Nerve ring from anterior end 56 55 (51–63) 56
Nerve ring from anterior end as % of pharynx length 65 64 (56–73) 65
Secretory-excretory pore from ant. end 74 75 (63–82) 80 (74–84)
Secretory-excretory pore from ant. end as % of pharynx length 86 86 (78–92) 90 (86–94)
Anterior gonad length (to flexure) 104 (83–114)
Posterior gonad length (to flexure) 113 (93–124)
Vagina or spicules length 27 8 (6–10) 29 (27–31)
Rectum or gubernaculum length 9 16 (14–18) 8 (6–9)
Vagina length / BD 0.2 (0.2–0.3)
Rectum or spicules / ABD 1.4 0.8 (0.7–0.9) 1.4 (1.3–1.5)
SMNH

Department of Paleozoology, Swedish Museum of Natural History

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