Beatogordius nagalandis, Yadav, Arun K., Schmidt-Rhaesa, Andreas & Limatemjen,, 2017

Yadav, Arun K., Schmidt-Rhaesa, Andreas & Limatemjen,, 2017, First report of the Gondwana genus Beatogordius from India, with further records of two Chordodes species (Gordiida, Nematomorpha), ZooKeys 643, pp. 53-61 : 54-55

Beatogordius nagalandis sp. n. Figs 1, 2

Type locality.

P-Khel Viswema Village, Kohima, Nagaland, India, from the community tap water. Collected by Mrs Bazule Toso.

Holotype.

A single male specimen from the type locality; alcohol preserved pieces of holotype deposited in the Museum of Department of Zoology, NEHU, Shillong with the accession no. MDOZ/NEHU/INV/112.

Host.

unknown

Etymology.

The species has been named after one of the Indian states, Nagaland, from where the specimen was collected.

Diagnosis.

Cuticle in midbody with longitudinal elevated ridges, which sometimes branch and fuse. Ridges highest in the central part, lower in lateral parts. Surface of ridges with fine cracks perpendicular to longitudinal axis. Cuticle between the ridges with 4 µm long spines. Ridges change to isolated areoles towards the anterior, anterior tip free of cuticular structures. Posterior end of male with two tail lobes, each lobe about three times as long as wide. Cloacal opening surrounded by spines, further spines in the region posterior of the cloacal opening. Anterolateral bristlefields are likely present. Adhesive warts with a keel are present on the ventral side anterior of the cloacal opening.

Description.

The holotype is 130 mm long, with a diameter of 0.37 mm in the midbody region. The specimen is very light (yellowish-white) in colour. The posterior end has two tail lobes.

The cuticle is structured by long elevated bands or ridges running parallel to the longitudinal axis of the animal (Fig. 1 a–d). These bands sometimes branch or fuse, and branches may end blindly (Fig. 1b, c). In most observed regions the bands are composed of a higher central part and lateral lower parts (Fig. 1d, e). In some regions the lower parts were not clearly observed, but this may be due to a covering of dirt in the region between the bands. The surface of the bands contains numerous fine cracks orientated perpendicular to their axis (Fig. 1d). In some regions these cracks appear without a certain pattern and are only partial (Fig. 1e), in others they appear to separate the band into numerous subunits (Fig. 1d). The region between the bands is often filled with debris, in parts where the dirt could be removed there are bristles or spines which are up to 4 µm long (Fig. 1d, e).

In the anterior end, approximately 270 µm from the anterior tip, the longitudinal bands gradually turn into polygonal or irregularly shaped individual areoles (Fig. 2 a–c). Between these areoles solid spines of 1-2 µm length are scattered (Fig. 2d). The anterior most 75 µm are free of cuticular structures (Fig. 2a).

The posterior end has two tail lobes and contains the ventral cloacal opening (Fig. 2f). This is oval, approximately 20 × 45 µm in size and surrounded by circumcloacal spines (Fig. 2e). These spines are stout, approximately 5 µm long, which are apically branched. The cloacal opening is 30-35 µm from the point where the separation into two tail lobes starts. The tail lobes are approximately three times as long as broad (roughly 300 × 100 mm). Posterior to the cloacal opening, extending onto the inner side of the tail lobes, are conical spines, which decrease in size posteriorly (Fig. 2e, f). Anterolaterally of the cloacal opening are structures which could represent parts of anterocloacal bristle fields, but as there is some dirt and suboptimal cuticle preservation in this region, this observation has to be taken with caution (Fig. 2f, g).

In the ventral region anterior of the posterior end, modifications of the cuticle were observed. There are paired stripes, in which elevation with longitudinal keels of 7.5 to 10 µm occur (Fig. 2h, i). Eight rows of such keeled structures occur in one stripe.

Taxonomic remarks.

In most Beatogordius species, areoles are clearly recognized as the basic elements, which form the longitudinal lines, and should be considered a characteristic of the genus ( De Villalobos et al. 2003, Schmidt-Rhaesa and de Villalobos 2002). More or less continuous lines occur in Beatogordius sankurensis Sciacchitano, 1958 and Beatogordius wilsoni Sciacchitano, 1958 from Africa (see Schmidt-Rhaesa and de Villalobos 2002), Beatogordius lineatus Schmidt-Rhaesa & Bryant, 2004 from Australia ( Schmidt-Rhaesa and Bryant 2004), and Beatogordius chinensis Schmidt-Rhaesa, 2011 from China ( Schmidt-Rhaesa 2011). Among all the above-mentioned species, Beatogordius chinensis is the only species to display long spines in the region between the longitudinal bands. The difference from the Indian Beatogordius is that in Beatogordius chinensis the bands have a “pearl-collar” appearance, which means that they usually have broader and narrower regions, whereas in the Indian Beatogordius the bands are of continuous thickness. It might be supposed that the Indian and the Chinese species are closely related. Beatogordius chinensis is the only species reported outside former Gondwana continents, but the collecting locality in Yunnan province is very close to Nagaland province, approximately 300-400 km east.