Acutogordius finni Schmidt-Rhaesa & Schwarz, 2016

Schmidt-Rhaesa, Andreas, 2016, New records of Indian Nematomorpha, with the description of a new species from the genus Chordodes, Zootaxa 4158 (2), pp. 272-280 : 278

Acutogordius finni Schmidt-Rhaesa & Schwarz, 2016

( Figure 5 A–F)

Material examined. Two male specimens from the Tuirial River , in the vicinity of Aizawl, Aizawl District, Mizoram, India (23°47’08 N; 92°48’36 E). Collected on October 11, 2014 . The Tuirial River is a tributary of the Barak drainage (Brahmaputra-Ganga Basin). Deposited in the Zoological Museum in the Department of Zoology at Pachhunga University College, Aizawl-Mizoram, India, accession number PUCZM -A/V/16005.

Description of specimens. Both specimens are 240 mm long, one has a diameter of 0.6 mm, the other of 0.9 mm. They are light brown in colour, with a white anterior tip followed by a darker collar. The posterior end tapers, a postcloacal crescent is present. Therefore the specimens belong to the genus Acutogordius .

The body cuticle is covered by abundant stout bristles ( Fig. 5 A). In one specimen the bristles appear to form lines on both sides along the ventral midline ( Fig. 5 B). At the posterior end on the lateral sides of the tail lobes, the bristles become longer ( Fig. 5 C, D, F). The postcloacal crescent is semicircular and extends onto the tail lobes ( Fig. 5 C, D). In one specimen, a dense aggregation of short spines is present in the region of the distal tips of the postcloacal crescent and the aggregation extends slightly onto the anterior part of the inner side of the tail lobes ( Fig. 5 D, E). These spines are not present in the other specimen ( Fig. 5 C).

Remarks. The characters described above fit, at least in one specimen, to a species recently described from the Philippines ( Schmidt-Rhaesa & Schwarz 2016). The absence of a distinctive character like having the spines close to the tips of the postcloacal crescent is surprising. As both specimens described here correspond in other characters and were found in the same location it appears likely that they represent the same species. Either they are indeed two different species or the possession of spines is a highly variable character.

Figures

FIGURE 5. Acutogordius finni. A – C from specimen (1), D – F from specimen (2). A. The body cuticle contains short spines (encircled). B. In the ventral midline, cuticular spines are arranged in two longitudinal rows. C. Posterior end with cloacal opening (co), postcloacal crescent (pcc) and converging tail lobes. D. Posterior end showing the position of images E and F. E. Solid spines are present at the ends of the postcloacal crescent, in the anterior region of the inner side of the tail lobes. F. Spines on the cuticle become longer and more slender towards the end of the body.