G. arupi can be distinguished from its sympatric congener Garra kempi by the following characters: perforated lateral line scales 35-36 (vs. 40-42); vent to anal distance 52.0-60.0 (vs. 50.0-52.9%) pelvic to anal distance; predorsal scales 11-12 (vs. 13-14); circumpeduncular scales 16 (vs. 12); transverse scales between anal fin origin and lateral line 3½ (vs. 2½,); presence of a distinct submarginal band on the dorsal fin (vs. absence); presence of a weakly-developed proboscis and transverse band of tubercles on the snout tip (vs. absence); and the presence of 7-8 thin stripes on the caudal peduncle (vs. absence).
It is told apart from the sympatric G. lissorynchus in the following characters: predorsal scales 11-12 (vs. 14-15); branched dorsal fin rays 7 (vs. 6); branched anal fin rays 5 (vs. 4); transverse scales between the anal fin origin and the lateral line 3½ (vs. 4½); absence of a W-shaped color band on the caudal fin (vs. presence); absence of a rostral lobe on the snout (vs. presence); presence of a transverse band of tubercles on the snout tip (vs. absence); and vent to anal distance 52.6-60.0 (vs. 37.3-40.2%) pelvic to anal distance.
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)[8]. 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 species, G. micropulvinus and Ageneiogarra imberba, are placed in the Semilabeoina assemblage. The generic name Ageneiogarra Garman, 1912 was suggested for both, and the Catalog of Fishes and FishBase now use it for A. imberba. 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.
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