A Trematode Flatworm from the intestines of freshwater Fish in Hidalgo State, Mexico.

Trematode Flatworm infections are very common in freshwater Fish, but tend not to be well studied except in instances where they also cause infections in Humans or domestic animals. However in recent years it has been shown that these parasites can be very useful in understanding the evolution of freshwater ecosystems, as they have a much shorter generation time, and therefore evolve more rapidly, with different populations becoming reproductively isolated much more quickly than their hosts, which can provide insight into the movements of ancient waterways.

In a paper published in the journal ZooKeys on 16 February 2015, Christian Bautista-Hernández, Scott Monks and Griselda Pulido-Flores of the Centro de Investigaciones Biológicas at the Universidad Autónoma del Estado de Hidalgo and Rafael Miranda of the Department of Zoology and Ecology at the University of Navarra describe a new species of Trematode Flatworm from two species of Poeciliid Fish (Tooth Carp) from the Río Malila a tributary of the Río Conzintla in Hidalgo State, Mexico.

The new species is placed in the genus Paracreptotrema and given the specific name rosenthali, in honour of Gil Rosenthal of the Department of Biology at Texas A&M University. It was found in the intestines of two species of Fish, Xiphophorus malinche (Highland Swordtail) and Pseudoxiphophorus jonesii (Barred Killifish).

Ventral view of Paracreptotrema rosenthali; arrows indicate fragments of

eyespot pigment. Bautista-Hernández et al. (2015).

Members of the genus Paracreptotrema have previously been found in Poeciliid and Profundulid Fish in river basins in Central America, as far north as the Isthmus of Tehuantepec in southeastern Mexico. The Río Malila forms part of the Río Pánuco Basin, which is separated from these Fish populations be the Mexican Plateau, suggesting the historic presence of a previously unknown connection between these waterways.

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A new species of Toothcarp from Iran.

The Toothcarps of the genus Aphanius are the only Eurasian members of the Family Cyprinodontidae; all other members of the family are restricted to the Americas, where they are variously known as Pupfish, Flagfish and Killifish (the term Killifish is also used to describe a number of Fish in other families; some members of the genus Aphanius are also called Killifish). Toothcarp are small carnivorous fish found in rivers and ponds across southern Europe, North Africa and southwest Asia; they are not closely related to true Carp.

In a paper published in the journal ZooKeys on 17 August 2012, a team of scientists led by Azad Teimori of the Department of Earth and Environmental Sciences at Ludwig-Maximilians-University, and the Department of Biology at the Faculty of Sciences at Shahid-Bahonar University of Kerman, describe a new species of Toothcarp from Namak Lake basin in Markazi Province in north-central Iran.

The new species of Toothcarp was discovered during fieldwork in 2007 in a shallow pond in the Namak Lake basin, 5 km south east of the city of Arak. The pond was roughly  4 × 6 m, and fed by drainage from a natural spring. The water was warm (23℃), and semi-stagnant. The pool had a muddy bottom with some gravel and lacked vegetation; the surrounding area was dominated by Rushes and Bulrushes. The new Fish was the only species present, it was also found in a number of nearby springs.

The pool in which the new species of Toothcarp was discovered. Teimori et al. (2012).

The new species is named Aphanius arakensis, the Arak Toothcarp, it is a 22.5-38.5 mm fish that was identified as a probable new species on the basis of the distinctive male colouration (dark grey with blue bars, the females are grayish), and this was later confirmed on the basis of otolith (ear-bone) morphology and gene sequencing.

Aphanius arakensis. (Top) male. (Bottom) female. Teimori et al. (2012).

The number of species of Aphanius in Iran has increased rapidly in recent years, since it has been discovered that differences in male colouration usually reflect different species, suggesting that sexual selection is the major driver of speciation in the group here (and probably elsewhere). It is highly probable that more species will be described in the group in the near future.

Map showing the distribution of endemic Aphanius species in Iran. Teimori et al. (2012).

See also New species of Grenadier from Japan, Two new species of Asian Sea Bass from South Asia, New species of Priapiumfish from the Mekong Delta, Head-Butting in Giant Bumphead Parrotfish and Boney Fish on Sciency Thoughts YouTube.

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