Diplopeltoides linkei Jensen, 1991

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 : 23-25

Diplopeltoides linkei Jensen, 1991

Fig 9 . A–C; Table 6

Diagnosis

Diplopeltoides linkei is characterised by a body of 0.48–0.63 mm long; cuticle with longitudinal striation; cuticularised plate underlying cephalic cuticle around amphid present; cephalic sensilla setiform, 2–3 µm long; amphidial fovea an inverted U-shape, 14–19 µm long and 7–8 µm wide; narrow space between amphidial branches not ornamented; secretory-excretory pore located opposite to isthmus; tail conoid; testes opposed; spicules 29–36 µm long, strongly curved, with round manubrium and subcylindrical shaft; gubernaculum plate-like, without apophyses.

Material examined

SWEDEN: 1 ♂, Skagerrak, 58°28′22.1″–19.2″ N, 10°29′35.6″–43.6″ E, soft bottom 248–316 m deep, 11 Oct. 2012, “Inventering Bratten” leg. (SMNH-159564); 1 ♂, Gullmarn Fjord near Lysekil, 58°15.73′ N, 11°26.10′ E, mud from 53 m deep, 14 Aug. 2014, O. Holovachov and U. Jondelius leg. (SMNH-159565).

Description

Adult male

Body cylindrical, posteriorly tapering in tail region, weakly curved upon fixation. Cuticle coarsely annulated along entire body, except for smooth anterior end (annulation starts at level of posterior ¼ of amphid) and terminal part of tail; annules 3–4 µm wide at mid-body region; longitudinal striation is distinct under the light microscope, covers annules over entire body length. Somatic setae not observed. Labial region bluntly rounded. Cuticularised plate underlying cephalic cuticle around amphid strongly developed, extending from level of anteriormost edge of amphid to level of posteriormost edge, 18.5–19 µm long and 13–14.5 µm wide at base; cuticular plates connected with each other on ventral and on dorsal sides. Inner and outer labial sensilla not seen. Cephalic sensilla setiform, equal to 0.3 labial region diameters in length, their bases are located 3.5–4 µm from anterior end. Amphidial fovea an inverted U-shape with ventral branch longer than dorsal branch. Narrow space between amphidial branches (amphidial shield) not cuticularised and not ornamented. Stoma very small, its cuticularised lining is uniform with 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 large, orifices of pharyngeal glands indistinct. Nerve ring surrounding isthmus. Secretory-excretory system present; secretory-excretory pore located along ventral body line opposite to isthmus; secretory-excretory duct very short; renette cell not observed. Tail conoid. Caudal glands opening via three separate openings, spinneret absent. Reproductive system diorchic, testes opposed: anterior testis outstretched and posterior testis reflexed. Spicules paired and symmetrical, strongly curved, with round manubrium and subcylindrical shaft. Gubernaculum plate-like, without apophyses. Caudal setae: two subventral pairs and single subdorsal.

Female

Not found.

Remarks

The recently collected population of D. linkei is similar to the type specimens from the Norwegian Sea in general morphology, structure of cuticle and anterior end, except for the somewhat longer body (0.62–0.63 mm vs 0.48–0.50 mm in type specimens) and longer spicules (32–36 µm vs 29 µm).

Figures

Fig. 9. A–C. Diplopeltoides linkei Jensen, 1991, male. A. Anterior end, surface view. B. Pharyngeal region, optical median section. C. Tail. — D–G. Diplopeltoides longicaudatus sp. nov., male. D. Tail. E. Anterior end, surface view. F. Pharyngeal region, optical median section. G. Cloacal region. Scale bar: A–C, E–G = 20 µm, D = 40 µm.

Tables

Table 6. Measurements (in µm) of Diplopeltoides linkei Jensen, 1991, Diplopeltoides longicaudatus sp. nov. and Diplopeltoides grandis sp. nov. (for D. linkei: each male individual measurement separated with a semicolon; “?” indicates that the character can not be observed or measured).

Species	linkei	longicaudatus sp. nov.	grandis sp. nov.
Sex	male	holotype male	holotype female
Number of specimens	2	1	1
Body length	639; 623	1031	2063
Body diameter (BD)	28; 32	20	44
Pharynx length	128; 133	67	131
Tail length	86; 81	93	125
Anal body diameter (ABD)	24; 24	15	30
a	23.1; 19.6	51.5	47.5
b	5.0; 4.7	15.4	15.7
c	7.4; 7.7	11.1	16.5
c’	3.7; 3.3	6.4	4.2
V or T (%)	52.5; 53.6	38.1	58.7
Labial region diameter	10.0; 10.5	5.0	14.0
Cephalic setae length	3.0; 3.0	13.0	18.5
Amphid from anterior end	6.0; 7.0	8.0	12.5
Dorsal amphid branch length	17.0; 18.5	6.0	30.0
Ventral amphid branch length	18.0; 19.0	5.0	25.0
Amphid width	7.5; 8.0	4.0	14.0
Nerve ring from anterior end	75; 81	?	97
Nerve ring from anterior end as % of pharynx length	59; 61	?	74
Secretory-excretory pore from ant. end	95	53	99
Secretory-excretory pore from ant. end as % of pharynx length	74	79	76
Anterior gonad length (to flexure)	–	–	310
Posterior gonad length (to flexure)	–	–	262
Vagina or spicules length	32; 36	27/31	10
Rectum or gubernaculum length	7; 4	?	18
Vagina length / BD	–	–	0.2
Rectum or spicules / ABD	1.4; 1.5	1.9/2.1	0.6