This species may have appeared in the aquarium trade under the misapplied names Puntius arulius and P. tambraparniei in the past, both of which are also now classified within Dawkinsia.
See the relevant profiles for D. arulius and D. tambraparniei for additional information regarding that confusion, since here we concentrate on D. rubrotincta.
It was initially described by Jerdon in 1849 but placed in synonymy with P. arulius by Day (1878), where it remained for over 100 years before being revalidated by Knight et al. (2011) and placed within the Puntius filamentosus 'group' of related species which also contained P. arulius, P. assimilis, P. exclamatio, P. filamentosus, P. rohani, P. rubrotinctus, P. singhala, P. srilankensis, and P. tambraparniei, but all of these were moved to the new genus Dawkinsia by Pethiyagoda et al. (2012).
Dawkinsia species are defined by the following combination of characters: adult size normally 80 – 120 mm3.1 – 5 in SL; rostral barbels absent; maxillary barbels present or absent; last unbranched dorsal-fin ray smooth; 4 unbranched and 8 branched dorsal-fin rays; 3 unbranched and 5 branched anal-fin rays; lateral line complete, with 18-22 scales on body; gill rakers simple, acuminate (not branched or laminate); no antrorse predorsal spinous ray; free uroneural present; 4-5 supraneurals; 15 precaudal and 14-17 caudal vertebrae; post-epiphysial fontanelle absent; infraorbital 3 slender, not overlapping preoperculum; juvenile (< 50 mm2.0 in SL) colour pattern consisting of three black bars on body, retained in adults of some species; a black, horizontally elongate blotch on the caudal peduncle in adults.
D. rubrotincta is easily told apart from most congeners since it possesses three, vs. 2, dark markings on the body, a character shared only with D. arulius, D. srilankensis, and D. tambraparniei.
However in P. rubrotinctus the three markings are relatively small and well-defined, measuring just two scales high and three wide, whereas in the other three species they are much larger and more diffuse.
It further differs from D. arulius in the following characters: dorsal to hypural distance 49.8 - 54.6 % SL vs. 57.3 - 57.6 % SL; interorbital width 28.4 - 35.6 % HL vs. 39.1 - 39.7 % HL; 10(8) - 11(4) gill rakers in the first gill arch vs. 8(3).
It differs from D. tambraparniei and D. srilankensis by possession of a more terminal mouth vs. sub-terminal (D. tambraparniei) or inferior (D. srilankensis) and lacking filamentous extensions to the dorsal-fin in males (vs. presence in D. tambraparniei and D. srilankensis).
It also has a longer maxilla than D. tambraparniei (26.5 - 32.3 % HL vs. 19.0 - 21.6 % HL) and is further separated from D. srilankensis by the following characters: head length 28.3 - 32.8 % SL vs. 24.8 - 26.7 % SL; body depth 34.9 - 41.8 % SL vs. 28.0 - 31.9 % SL; interorbital width 28.4 - 35.6 % HL vs. 37.8 - 42.5 % HL; barbels 7.3 - 13.4 % HL vs. 0.0 - 1.8 % HL.
The precise relationships within the genus are still open to question in some respects with Knight et al. (2011) suggesting that members may hybridise naturally at some localities.
For example, a D. arulius-like fish (possibly D. rubrotincta) co-occurs with D. assimilis in the Kallada River at Thenmalai, which also happens to be the type locality of D. exclamatio.
The latter is somewhat anomalous since it's the only Dawkinsia species other than D. rubrotincta to feature a (roughly) W-shaped mid-lateral blotch, but also has a laterally-elongated blotch on the caudal peduncle as in other genus members.
D. exclamatio should also have a sub-terminal mouth and lack dorsal-fin filaments but some specimens possess a terminal mouth and/or possess dorsal filaments, and one specimen also had black caudal-fin tips as typically seen in D. filamentosa, whereas the description states that the fin tips are only dusky and lack distinctive markings.
Forms apparently intermediate between D. filamentosa and D. tambraparniei have also been collected where the two occur together in the Thamirabarani River, Tamil Nadu.
While no conclusions were reached because DNA testing was not performed, hybridisation between D. filamentosa and D. arulius in that river had previously been speculated and is a phenomenon known to be more common in the family Cyprinidae than in any other group of fishes, meaning future research may yield interesting results.
The genus Puntius was for a number of years viewed as a polyphyletic catch-all containing over 100 species of small to mid-sized cyprinid until Pethiyagoda et al. (2012) published a partial review covering South Asian members.
The majority of sub-Himalayan Puntius species were reclassified and new genera Dawkinsia, Dravidia, and Pethia erected to accomodate some of them, with the remainder either retained in Puntius or moved to the existing Systomus assemblage, though the definition of the latter was altered meaning some Southeast Asian species formerly placed there are no longer members.
It subsequently became clear that the name Dravidia was preoccupied by a genus of flesh fly, therefore the replacement name Haludaria was made available by Pethiyagoda (2013).
No species from Indochina, China, or Indonesia were included in the study meaning a significant number of former Puntius are currently classed as incertae sedis, i.e., of uncertain taxonomic placement, and this also applies to a number of South Asian species of unresolved status.
They’re perhaps best referred to as ‘Puntius‘ for the time being whereby the genus name is surrounded by quotation marks to denote its questionable usage, and that is the convention used here on SF.
Editing needs JavaScript. This is the text as it was last saved.