Mudwigglus micramphidium, Holovachov, 2017

Holovachov, Oleksandr, 2017, Belgopeltula belgica (Vincx & Gourbault, 1992) gen. et comb. nov. and Mudwigglus micramphidium sp. nov. from the west coast of Sweden, and reappraisal of the genus Pseudaraeolaimus Chitwood, 1951 (Nematoda: Araeolaimida: Diplopeltidae), European Journal of Taxonomy 383, pp. 1-21 : 10-12

Mudwigglus micramphidium sp. nov.

urn:lsid:zoobank.org:act:C5028B8C-5860-45B6-A1D0-DBF6E1B30ED2

Fig. 3 ; Table 1

Diagnosis

Mudwigglus micramphidium sp. nov. is characterised by a body of 0.6 mm long; cephalic sensilla 1.5 µm long; amphidial fovea an inverted U-shape, 8 µm long and 3.5 µm wide; gymnostom without cuticularised ring; tail elongate conoid, with subcylindrical distal part; terminal setae absent; spicules 15 µm long; gubernaculum present; two midventral precloacal setae.

Etymology

The specific epithet refers to the overall similarity between the new species and M. macramphidium , as well as one of the major differences between these two species (amphid size).

Material examined

Holotype

SWEDEN: ♂, Skagerrak , 58°28′12.1″ –19.5″ N, 10°37′01.1″ –07.1″ E, soft bottom 180–216 m deep, 10 Oct. 2012, “Inventering Bratten” leg. ( SMNH Type-8889 ).

Description

Adult male

Body cylindrical, tapering posteriorly in the tail region, strongly ventrally curved upon fixation. Cuticle finely striated along the entire body, annules without longitudinal striation or any other ornamentation visible under the light microscope. Somatic setae present, sparsely distributed over entire body, with one ventrosublateral pair in the pharyngeal region just posterior to nerve ring, and three pairs along the tail: one dorsosublateral pair short distance posterior to cloacal opening, one ventrosublateral pair at about the middle of tail length, and one sublateral pair close to tail terminus. Labial region truncate conoid; lips fused. Inner and outer labial sensilla not observed. Cephalic sensilla small setiform, equal to 0.2 labial region diameters in length, their bases are located 5 µm from anterior end. Amphidial fovea an inverted U-shape with its dorsal branch slightly longer (8 µm) than ventral branch (6.5 µm). Amphidial fovea length (longest) to width ratio is 2.2. Narrow space between amphidial branches not refractive and not ornamented. Distinct cell with large nucleus is located behind the amphid, and is connected to amphidial fovea. Stoma very small, but distinctly subdivided into three sections: cheilostom narrow tubular, 3 µm long; gymnostom truncate conoid, narrowing towards anterior end, with weakly cuticularised walls, 3 µm long and 2 µm wide, without cuticularised ring; stegostom very short conoid, its lining is uniform with the lining of the pharynx. Pharynx distinctly subdivided into anterior corpus and posterior basal bulbus; corpus subcylindrical, muscular; basal bulbus ovoid, muscular. Dorsal pharyngeal gland nucleus located in the basal bulbus; dorsal pharyngeal glad orifice penetrates pharyngeal lumen at the base of the stoma. Ventrosublateral pharyngeal gland nuclei and orifices indistinct. Nerve ring encircling pharynx at posterior third of its length. Secretory-excretory system present; renette cell located opposite to the ventral side of the basal bulbus and anterior part of the intestine; secretory-excretory pore opens to the exterior at level of the basal bulbus. Reproductive system diorchic; anterior testis outstretched, posterior testis outstretched, with posteriorly reflexed terminal section of the germinal zone. Large spermatogonia are visible. Spicules paired and symmetrical, arcuate, with weakly developed manubrium and subcylindrical shaft. Gubernaculum present, platelike. Male accessory apparatus composed of two midventral precloacal setiform sensilla. Tail elongate conoid, subcylindrical distally. Terminal setae absent. Caudal glands and their outlets obscure.

Female

Not found.

Remarks

Mudwigglus micramphidium sp. nov. closely resembles M. macramphidium described from New Zealand ( Leduc 2013) in general body size ( Table 2 ), shape and length of the tail and absence of gubernaculum apophysis. The new species can be separated from M. macramphidium in having shorter amphid (amphid length/width ratio 2.2 in M. micramphidium sp. nov. vs 3.5 in M. macramphidium ), shorter spicules (15 µm in M. micramphidium sp. nov. vs 23–25 µm in M. macramphidium ), male accessory apparatus (two precloacal setae in M. micramphidium sp. nov. vs one precloacal setae and two tubular supplements in M. macramphidium ).

Figures

Fig. 3. Mudwigglus micramphidium sp. nov., holotype male (SMNH Type-8889) entire view. Scale bar = 20 µm.