Scientists have described four new species of kuhli- or eel-loaches from Myanmar and India.
Ralf Britz and James Maclaine of the Natural History Museum in London undertook a review of the Pangio species of Myanmar (formerly Burma) and named three new species, Pangio signicauda, P. lumbriciformis and P. elongata. They also described a new species from India called Pangio apoda.
The review, which was published in the latest edition of the journal Ichthyological Exploration of Freshwaters, looked at all of the Pangio species found in Myanmar.
The Pangio genus, which contains around a further 25 species, is best represented in the Sunda Islands, which are home to a total of 16 species.
Comparatively fewer Pangio species are known from India and Myanmar. Pangio pangia, P. longipinnis and P. goaensis are known from India, while P. pangia and P. fusca occur in Myanmar.
Pangio signicaudaPangio signicauda is known from the Ayeyarwaddy basin in Myanmar and has a unique colour pattern within the Pangio genus.
Britz and Maclaine said that it had a number of "dark saddle-like marks on the dorsum, a dark transverse stripe or double-spot at the caudal fin base and a horizontal stripe and a transverse subdistal band in the caudal fin".
Pangio lumbriciformisLike P. signicauda, the new species Pangio lumbriciformis also has dark saddle-like marks and a dark double-spot on the tail:
"Body with a light grey to whitish background. Dorsum and sides very sparsely covered with numerous tiny, round, black spots of 10-25μm diameter. Aggregations of spots form a series of up to 20 dark saddles that are relatively distinctly set apart from the background.
"Density of spots decreasing along sides, so that ventral side is devoid of any spots. A longitudinal stripe of subdermal pigment along horizontal septum quite well developed."
It is more slender than P. signicauda, with a body depth of 10.8-13.8 of SL, compared to 13.6-15.4 of SL. The caudal peduncle is also considerably slimmer.
Pangio apodaPangio apoda was discovered in the Brahmaputra drainage in West Bengal, India, by Heok Hee Ng. Older specimens were also found in the Natural History Museum's collections which date back to 1932, and were collected in Sevoke stream in Calcutta.
Like Pangio pulla and Pangio fusca, Pangio apoda lacks the pelvic girdle and associated pelvic fins - hence the Latin name, which roughly translates to "without foot".
It is a drab, uniform light to reddish brown colour without any markings. It is believed to be restricted to the Tista drainage in West Bengal.
Pangio elongata
Pangio elongata is known from two streams in Tenasserim and Mitan Chaung in Tanintharyi province in Myanmar. Records suggest that the species has been collected as early as 1887 when it was caught by Fea at Meetan, but the species was recorded by Vinceguerra as P. pangia a couple of years later.
The nondescript brown loach, has a uniform light or reddish brown colour and lacks markings. It is laterally compressed, with a body depth 12.3 times standard length and a body width of 2.1 times in its depth.
Britz and Maclaine said that Pangio elongata cannot be easily assigned to any of the four species groups identified by Kottelat and Lim, as although it shares the plain colouration seen in members of the oblonga group, vertebral counts are much higher.
Pangio taxonomyBritz and Maclaine said that counting the number of fin rays was not without difficulty: "We counted only eight pectoral fin rays and six pelvic fin rays in the alcohol specimens of P. signicauda and P. lumbriciformis, whereas the cleared and double stained specimens of the two species showed nine pectorial fin rays and seven pelvic fin rays.
"The difference is due to the tiny size of the medialmost ray in both fins, which, if present, may be missed in alcohol specimens. We therefore expect some other counts, which in some species are based exclusively on alcohol specimens, to be one short of the actual number of rays in the fins."
The authors did not study type material of P. goaensis or P. longipinnis, but stated that they had doubts as to whether Pangio longipinnis was actually a member of the Pangio genus at all.
"The dorsal fin in the 62mm holotype and only specimen of P. longipinnis is situated opposite the pelvic fins, rather than between the level of the pelvic and anal fins, a character that sets P. longipinnis apart from all other known Pangio species.
"From the description and the accompanying illustrations we think that P. longipinnis is rather a species of the genus Lepidocephalichthys, a conclusion which is supported by the caudal-fin spot of 'P. longipinnis', a common marking in the colour pattern of Lepidocephalichthys species.
For more information see the paper: Britz R and J Maclaine (2007) - A review of the eel-loaches, genus Pangio, from Myanmar (Teleostei: Cypriniformes: Cobitidae). Ichthyological Exploration of Freshwaters, Vol. 18, No. 1, pp. 17-30.