Axonolaimus de Man, 1889

Ansari, Kapuli Gani Mohamed Thameemul, Lyla, Somasundharanair & Khan, Seyd Ajmal, 2018, New distributional records of free-living marine Nematodes from Indian waters IV. Linhomids and Axanolaimids, Records of the Zoological Survey of India 118 (4) : -

Genus Axonolaimus de Man, 1889

5. Species: Axonolaimus paraspinosus Stekhoven & Adam, 1931

Synonym: Axonolaimus similis Schulz, 1932

Material examined: 2 males collected from Cuddalore – SIPCOT 30-50m depth(19.12.2008)and Tammenapatanam 151- 150m depths (16.12.2008).

de Man ratio: a b c Male: 48.14-49.32 7.96-8.14 6.97-7.16

Description: Body length 1-1.2mm. Maximum diameter 35-37µm. Cuticle finely striated. Six small cephalic papillae. Four(5-8µm) cephalic setae and four subcephalic setae about half the length and situated just posterior to the cephalic setae. Somatic setae short and sparse mainly confined to cervical and caudal regions. Loop-shaped amphids (3-7µm in diameter) wide. Buccal cavity long and double conical shape with longitudinal cuticularised ridges in the anterior part. Oesophagus(135-141µm) widens posteriorly, but with no distinct bulb. Tail (7.9-8.6a.b.d.) conical except for the posterior eighth, with a slight terminal dilation. Spicules 33-36µm. Gubernaculum with two 16-18µm posteriorly directed de Man ratio: a b c

Male: 38.99±0.17 5.44±0.31 11.56±0.29 (38.79-39.14) (5.12-5.86) (11.22-11.89)

Female: 41.12 5.64 12.18 apophysis. 19-21 precloacal supplements consisting of minute ventral pits ( Figure 5 ).

Female: Not found

Feeding type: The specimens showed large buccal cavity that is not armed with teeth.According to the classification of buccal cavity by Wieser (1953), this species is a nonselective deposit feeder (1B).

Habitat: Sandy and silty sediments. Description: Body length 0.9-1.2mm in male and 1.1mm in female.Maximum diameter 23-25µm in male and 24µm in female. Cuticle finely striated. Six cephalic papillae. Four cephalic setae (18-21µm). Subcephalic setae in two whorls: four (8-11µm) in submedian positions, about halfway down the length of amphids; second whorl of four (9-12µm) sublateral and four (3-6µm) submedian setae jest posterior to amphids. Somatic setae up to 14-16µm, sparsely scattered along the length of the oesophagus, but virtually absent from the remainder of the body except for the tail. Loop-shaped amphids (6-10µm in diameter). Buccal cavity with odontia pointed anteriorly.Oesophagus cylindrical (185-199µm in male and 188µm in female) without posterior bulb. Tail conical (4.6-5.2a.b.d. in male

4.8a.b.d. in female). Spicules 15-23µm, uniformly curved, proximally cephalate. Gubernaculum with 7-12µm dorsal apophysis. Indistinct papilliform precloacal supplements, apparently only four. Two ovaries. Vulva present at 56- 58% of body length ( Figure 6 ).

Feeding type: The specimens showed large buccal cavity that is not armed with teeth.According to the classification Distribution: India: Cuddalore –SIPCOT and Tammenapatanam. Elsewhere: Netherland ( Hansson, 1998); England ( Warwick et al., 1998); European waters ( De Smet et al., 2001); English Channel, Belgium, Finland and Kieler Buchat ( Hansson, 1998).

Remarks: The specimens examined conformed well to the earlier description of Warwick et al. (1998) except for the smaller body size. The total body length described was

1.3-1.7mm and tail length 4.6a.b.d. The body length of the specimen studied at present was found smaller being 1-1.2mm and the tail length 7.9-8.6a.b.d. This is the first record of the species from the Indian waters.

Figures

Figure 5. Axonolaimus paraspinosus Stekhoven & Adam, 1931 a) entire male, b) male head, c) male tail.

Figure 6. Odontophora exharena Warwick and Platt, 1973 a) entire male b) male head, c) male tail, d) female head, e) female tail, f) entire female.