A new roundworm species from India is a link between 2 genera

April 13, 2016, Pensoft Publishers
Biogeographical distribution of species of Acrostichus Rahm 1928. Credit: Dr. Qudsia Tahseen

The unique features and blending characters of a new roundworm species, discovered in India, make the nematode a distinct yet intermediary or connecting link between two supposedly distant genera. The new worm is a hermaphrodite that primarily feeds on bacteria. The study, conducted by a research team from the Aligarh Muslim University, India, led by Dr Qudsia Tahseen, is published in the open access Biodiversity Data Journal.

The newly discovered nematode belongs to the genus Acrostichus, which is reported from all continents except Australia. The biogeographical records show larger distribution of these in subtropical to temperate regions (Image 3). They can be found in soil, fresh water, polluted water, decaying matter and even in beetle feces.

The new roundworm, called Acrostichus medius, is hereby reported from soil rich in organic matter. The population comprises of both hermaphroditic female and males (Image 2). The species seems to serve a transitional role in the evolutionary process linking the Acrostichus and Diplogastrellus genera.

The narrow mouth cavity eliminates the possibility of predation thus leaving bacteriophagy as the only option in terms of its feeding behavior.

The new species is unique in possessing robust male copulatory organs (spicules) having furcate distal ends with fine extensions and a ventral attenuated arm. Such copulatory organs are unusual for the group and it also reflects a more complex type of copulation process involving elaborately-built female vagina.

New roundworm, Acrostichus medius: anterior end (left) and uterine region (right) of a hermaphroditic female. Credit: Dr. Qudsia Tahseen

Apart from other intermediate characters, the new species possesses paired female genital branches with a gradual reduction in the posterior genital branch up to the extent of the post-uterine sac in some individuals. Thus, the new species seems to be a transitional species in the evolutionary process and shows affinities to both Acrostichus and Diplogastrellus genera.

The characters of twenty species were taken for cluster analysis of Acrostichus. In the constructed phylogram (Image 1), Diplogastrellus cerea, a species of closely related genus, stands out from all species of Acrostichus. The A. medius occupies an intermediate position between the outgroup species and other congeners.

Phylogram showing relationship between species of Acrostichus Rahm 1928 based on morphological data with Diplogastrellus cerea as an outgroup. Credit: Dr. Qudsia Tahseen

Explore further: A new jumping spider with mating plug discovered from the 'Western Ghats'

More information: Qudsia Tahseen et al. Description of a new species of Acrostichus Rahm 1928 (Nematoda: Diplogastridae) from India with a note on its position and relationship with the congeners, Biodiversity Data Journal (2016). DOI: 10.3897/BDJ.4.e8029

Related Stories

Researchers describe three new species of fruit flies

October 2, 2015

Acanthiophilus is a genus of fruit flies that infest plants of the tribe Cardueae (thistles) within the family Asteraceae. Members of this genus live in Africa, the Canary Islands, Europe, and Asia. Some species of Acanthiophilus ...

Recommended for you

A decade on, smartphone-like software finally heads to space

March 20, 2019

Once a traditional satellite is launched into space, its physical hardware and computer software stay mostly immutable for the rest of its existence as it orbits the Earth, even as the technology it serves on the ground continues ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.