Garra rakhinica KULLANDER & FANG, 2004

Etymology

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”.

rakhinica: named for the Rakhine Yom mountains/Rakhine state in Myanmar, to which it is endemic.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

This species is known only from its type locality, a minor stream draining in to the Bay of Bengal from the western slope of the Rakhine Yoma mountain range in western Myanmar.

Type locality is ‘Taunggok, Thade River drainage, Yan Khaw Chaung, about 4 kilometers on logging road from Gwetauk village, 23 kilometers on road Taunggok-Pyay, 18°47’48″N, 94°21’46″E, Rakhine State, Myanmar’.

Habitat

In March 1998 the type locality comprised a small forest river reduced to a series of interconnected remnant pools with a width of approximately 2 m and maximum depth of 1 m. The water was clear and still or flowing slowly in places with a substrate of gravel, pebbles, and larger rocks, and there was no aquatic vegetation.

Sympatric fish species included Brachydanio feegradei, Devario xyrops, Garra vittatula, Xenentodon cancila, and Sicyopterus fasciatus, plus unidentified species of Lepidocephalichthys and Channa.

Maximum Standard Length

50 – 60 mm.

NotesTop ↑

G. rakhinica can be distinguished from other members of the genus by the following combination of characters: rostral furrow shallow and snout tip smoothly rounded; rostral lobe present, proboscis absent; scaled predorsal region, chest, and abdomen; two pairs of barbels; 28 lateral line scales; 16 circumpeduncular scale rows; colour pattern almost uniform greyish on body and caudal-fin; a dark spot immediately posterior to the upper extremity of the opercle; lower caudal-fin lobe with blackish marking close to tip, tip white; tip of upper caudal-fin lobe white.

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). 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.

References

1. Kullander, S. and F. Fang, 2004 - Ichthyological Exploration of Freshwaters 15(3): 257-278
   Seven new species of Garra (Cyprinidae: Cyprininae) from the Rakhine Yoma, southern Myanmar.
2. Kottelat, M., 2013 - Raffles Bulletin of Zoology Supplement 27: 1-663
   The fishes of the inland waters of southeast Asia: a catalogue and core bibiography of the fishes known to occur in freshwaters, mangroves and estuaries.
3. Stiassny, M. L. J. and A. Getahun, 2007 - Zoological Journal of the Linnean Society 150(1): 41-83
   Phylogenetic relationships of labeonine cyprinids of the disc-bearing group (Pisces: Teleostei).
4. Yang, L., M. Arunachalam, T. Sado, B. A. Levin, A. S. Golubtsov, J. Freyhof, J. P. Friel, W-J. Chen, M. V. Hirt, R. Manickam, M. K. Agnew, A. M. Simons, K. Saitoh, M. Miya, R. L. Mayden, and S. He, 2012 - Molecular Phylogenetics and Evolution 65(2): 362-379
   Molecular phylogeny of the cyprinid tribe Labeonini (Teleostei: Cypriniformes).
5. Zhang, E., 2005 - Zoological Studies 44(1): 130-143
   Phylogenetic relationships of labeonine cyprinids of the disc-bearing group (Pisces: Teleostei).