Garra poecilura

Garra: vernacular Gangetic name for a particular species of “sand-digger,” which Francis Buchanan-Hamilton applied as a generic name for bottom-dwelling cyprinids “with no affinity to another genus”.

poecilura: from the Ancient Greek ποικιλος (poecilio-), meaning 'variegated', and ονρα (oura), meaning 'tail', in reference to the vividly-patterned caudal peduncle and caudal-fin.

This species is known only from its type locality, a minor tributary within the Irrawaddy River system draining the eastern slope of the Rakhine Yoma mountain range in western Myanmar.

Type locality is 'Irrawaddy River drainage, Naung Pin Thar Chaung, a small stream at logging road about 1 kilometer from Ngathaingchaung-Gwa road, 17°31'44"N, 94°48'46"E, Ayeyarwaddy Division, Myanmar'.

The Naung Pin Thar Chaung is located in a hilly area mostly comprising bamboo forest. In 1998 the water was clear, colourless and flowing at a moderate pace over a substrate of rocks and gravel. It was 1-2 metres wide and maximum depth was only 0.5 metres.

Due to the surrounding forest some stretches were shaded and others more open. Sympatric species included Garra spilota, Homalopteroides modestus, Mystus pulcher, and Xenentodon cancila, plus unidentified members of Brachydanio, Schistura, Syncrossus and Channa.

G. poecilura can be distinguished from other members of the genus by the following combination of characters: rounded snout; rostral lobes with tubercules present, proboscis absent; scaled predorsal region, chest, and abdomen; two pairs of barbels; 29 lateral line scales; 16 circumpeduncular scale rows; colour pattern including a weakly-defined horizontal band or series of dark blotches on the flank, a dark brown spot immediately posterior to the upper extremity of the opercle, two vertical rows of black spots on the caudal-fin.

The genus Garra is a particularly enigmatic grouping with new taxa described on a regular basis, while many of the existing ones may represent cases of misidentification or synonyms of other species. Some of the revisions have also been called into question, which has added further confusion. A full generic review would be ideal but is unlikely to materialise given the extensive distribution of its members which range from southern China across much of southeast Asia, India and the Middle East as far as north/central Africa.

Instead a number of less-extensive works published in recent years have resulted in a gradual, but continuing, improvement in knowledge, and it remains possible that the genus will be broken up into smaller taxa since the current assemblage is almost certainly polyphyletic.

Garra species are usually included in the subfamily Labeoninae/Cyprininae or tribe Labeonini (name varies with author) which by recent thinking is further divided into four subtribes; Labeoina, Garraina, Osteochilina, and Semilabeoina (Yang et al., 2012)[5]. The putatively monophyletic Garraina comprises a number of genetic lineages including Garra sensu stricto (which also includes Horalabiosa, Phreatichthys and possibly other genera), a small clade comprising Garra cambodgiensis and G. fascicauda (thus rendering Garra polyphyletic), Paracrossocheilus, and Gonorhynchus (which includes Akrokolioplax).

Two Garra species, G. imberba and G. micropulvinus, are placed in the Semilabeoina assemblage, and the generic name Ageneiogarra Garman, 1912 has been suggested for them, although this does not appear to have been widely followed (e.g. Kottelat, 2013). In addition, some genera which were previously considered to be close relatives of Garra species such as Discogobio, Discocheilus and Placocheilus, are now also placed in this subtribe.

All genera currently included in Garraina possess a lower lip modified to form a mental adhesive disc, allowing the fish to cling to surfaces in turbulent conditions. In most species the upper lip is almost entirely reduced and both the upper and lower jaw margins are keratinised, i.e., horny, and used to scrape food items from the substrate.

Garra species are distinguished from other Garraina members by the first two pectoral-fin rays usually being thickened, fleshy and unbranched, possession of 10-11 dorsal-fin rays, and a combination of internal characters. Some species have evolved particular environmental specialisms such as highly reduced eyes in hypogean forms or the ability to survive in thermal springs.