Diplopeltoides longicaudatus, 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 : 26

Diplopeltoides longicaudatus sp. nov.

urn:lsid:zoobank.org:act:048C4270-0463-408E-89EE-8D6B2A8E61C3

Fig. 9 D–G; Table 6

Diagnosis

Diplopeltoides longicaudatus sp. nov. is characterised by a body of 1.03 mm long; cuticle without longitudinal striation; cuticularised plate underlying cephalic cuticle around amphid present; cephalic sensilla setiform, 13 µm long; amphidial fovea an inverted U-shape, 6 µm long and 4 µm wide; narrow space between amphidial branches not ornamented; excretory pore indistinct; tail elongate conoid; spicules unequal in size, 27–31 µm long, arcuate, with small ovoid manubrium and subcylindrical shaft; gubernaculum absent; midventral precloacal cuticular ridge present.

Etymology

The specific epithet refers to the characteristic long tail in this species.

Type material

Holotype

SWEDEN: ♂, Skagerrak , 58°20.32′–20.38′ N, 11°12.73′–12.68′ E, coarse shell sand 14–17 m deep, 19 Aug. 2014, O. Holovachov and U. Jondelius leg. ( SMNH Type-8843 ).

Description

Adult male

Body cylindrical, posteriorly tapering in tail region, strongly ventrally curved upon fixation. Cuticle finely annulated along entire body, except for smooth anterior end and terminal part of tail; annules 1.5 µm wide at mid-body region; longitudinal striation not observed under light microscope. Somatic setae indistinct. Labial region truncate conoid; lips fused. Cuticularised plate underlying cephalic cuticle around amphid weakly developed, extending from level of cephalic setae bases to posteriormost edge of amphid, 9 µm long and 7.5 µm wide at base; cuticular plates connected with each other on ventral and on dorsal sides. Inner and outer labial sensilla not observed. Cephalic sensilla setiform, equal to 2.7 labial region diameters in length, their bases are located 1.5 µm from anterior end. Amphidial fovea an inverted U-shape with dorsal branch longer than ventral branch. Narrow space between amphidial branches (amphidial shield) not cuticularised and not ornamented. Stoma very small, its cuticularised lining uniform with lining of the pharynx. Pharynx distinctly subdivided into anterior corpus and posterior postcorpus; corpus fusiform, muscular; postcorpus consists of anterior narrow non-muscular isthmus and weakly developed basal swelling. Pharyngeal gland nuclei and orifices indistinct. Nerve ring not observed. Secretory-excretory system not observed. Tail elongate conoid. Caudal glands opening via three separate openings, spinneret absent. Reproductive system obscure. Spicules paired and somewhat unequal in size, arcuate, with small ovoid manubrium and subcylindrical shaft. Gubernaculum absent. Midventral cuticular ridge extending anteriorly from about level of middle of spicules for 150 µm towards mid-body. Caudal setae not observed.

Female

Not found.

Remarks

Diplopeltoides longicaudatus sp. nov. is unique among known species of Diplopeltoides in having a precloacal cuticular ridge in males – a feature found in several species of the related genus Tarvaia Allgén, 1934 ( Holovachov et al. 2012). In having a cuticularised plate underlying the cuticle of the anterior end, the new species is similar to D. ornatus , D. linkei , D. axayacatli , D. grandis sp. nov. and D. suecicus sp. nov. The new species further differs from D. ornatus and D. linkei in the structure of cuticle (smooth vs striated under the light microscope); a body length of 1.03 mm vs 0.43–0.63 mm, the length of the cephalic setae (13 µm vs 2–4 µm) and tail (c’ = 6.4 vs 3.2–4.2); it differs from D. axayacatli , D. grandis sp. nov. and D. suecicus sp. nov. in having no interamphideal shield (vs present and ornamented).

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.