Pseudoplatycoma malaysianis, Chen, Cheng-Ann, 2015

Chen, Cheng-Ann, 2015, A new marine nematode genus Pseudoplatycoma with a new species from the Sulu Sea and revision of the subfamily Platycominae (Enoplida: Leptosomatidae), Zootaxa 3905 (2), pp. 233-244 : 235-238

Pseudoplatycoma malaysianis n. gen. n. sp.

( Fig. 1–5 , Table 1)

Material examined. One male and one female.

Holotype Male, collected on 15 September 2012, Sulu Sea (15 m) depth, 7° 16' 57.68"N, 117° 1' 37.79"E. Sandy bottom. ( BMRI.NEM 0003).

Allotype Female ( BMRI.NEM 0003-1), same collection data as holotype.

Description. Male Body long (6686 µm). Body diameter uniform except near anterior and posterior ends; maximum about 150 µm. Head diameter about 26–27 µm. Cuticle smooth. Mouth surrounded by four low lips. Labial papillae not clearly observed. Eight cephalic setae. Three stout cervical setae at the posterior of the amphid. Four somatic setae on the left side ( Fig. 1 ) which are absent on the right side. One seta on esophageal region (as well as three stout cervical setae). Virtually no buccal cavity; mouth opening merging into oesophagus. Oesophagus cylindrical; length approximately one sixth of the total body length. Nerve ring about 340 µm from anterior. Amphids pocket-like and slightly pointed in the centre. Ocellus-like pigment spots present throughout the body region from posterior of the nerve ring (370 µm from anterior) to the anterior of the spicule. Pigment spot c.d. ranging from 31 µm to 41 µm. Tail conical.

Spicules paired, 100 µm long and slightly curved ventrally. Proximal end of spicule bluntly rounded. Distal end of spicule forming a screw-like pattern. Gubernaculum with paired dorsal apophyses, caudally directed. Paired subventral setae present at the cloaca. Three additional subventral setae located near a small pre-cloacal supplement. One caudal seta present at the tail region. Six pairs of heavily cuticularized paired tubular supplements located from 240 µm anterior to the cloaca.

Female. body larger than the male ( Table 1). Body shape similar to male but longer relative to length. Head diameter and amphid smaller than male. First pigment spot further from anterior and nerve ring compared to the male. Smaller pigment spots (23–25 µm). Vulva about 3700 µm from anterior, or 54 % of total body length. a.b.d. 71 µm. Reproductive system didelphic amphidelphic. Tail relatively longer than in male.

Characters Holotype Allotype Total body length 6686.0 6971.9 Head diameter 26.5 25.6

Length of cephalic setae 12.2 14.3

Amphid diameter 10.6 5.9

Amphid diameter / corresponding body diameter (%) 36.8 27.6

Nerve ring from anterior extremity of body 337.3 365.9

Oesophagus length 1169.6 1326.0 Oesophagus c.d. 70.1 69.9

Maximum body diameter 146.0 149.0

First pigment spot from anterior 373.1 449.1

First pigment spot from nerve ring 13.7 61.7

......continued on the next page Diagnosis. P. malaysianis n. gen. n. sp. is characterized by having four low lips, pocket-like amphids that are slightly pointed in the center, six pairs of heavily cuticularized paired tubular supplements, pigment spots throughout the body, a bluntly rounded spicule, gubernaculum apophyses caudally directed and a conical tail. There are no other species of the genus.

Etymology. The species name refers to the name of the country, Malaysia, where the species was found.

Figures

FIGURE 1. P. malaysianis n. gen. n. sp. a) Lateral view of male anterior body region. b) Lateral view of male posterior body region. Scale bar: A, B = 100 µm. PS = Pigment spots; SP = Subventral papillae.

FIGURE 2. P. malaysianis n. gen. n. sp. a) Lateral view of male head. b) Male copulatory apparatus. Scale bar: A, B = 20 µm.

FIGURE 3. P. malaysianis n. gen. n. sp. a) Lateral view of female head. b) Female posterior body region. Scale bar: A = 20 µm; B = 50 µm.

FIGURE 4. P. malaysianis n. gen. n. sp. a) Lateral view of a male anterior body region. b) Lateral view of a male posterior body region. c) Ocelli-like pigment spots. d) Male copulatory apparatus.

FIGURE 5. P. malaysianis n. gen. n. sp. a) Lateral view of male head. b) Lateral view of male head showing amphid. c) Lateral view of female head.