Note : - Sudasinghe et al., 2018 based on a phylogenetic study, resolved the issues raised in this post at the end. Now Rasboroides nigromarginatus is considered as a synonym of Rasboroides vaterifloris
Sudasinghe, H., Herath, J., Pethiyagoda, R. and Meegaskumbura, M. , 2018, ‘Undocumented translocations spawn taxonomic inflation in Sri Lankan fire rasboras (Actinopterygii, Cyprinidae)’. PeerJ [Online journal], (20 December 2018). Link >>
Endemic genus Rasboroides is restricted to the shaded rain
forest streams of South-western wet zone from Kalu to Walawe drainages. A single species of Rasboroides formerly
known as Rasbora vaterifloris was divided into four different species
recently base on morphological differences. Table 1 summarized some of their
morphological features with distribution in the country base on Batuwita S. et
al., 2013.
Rasboroides
nigromarginatus ( Black Line Golden Rasbora/කලු-ඉරි හල්මල්දන්ඩියා[Kaluiri Halmaldandiya])
Rasboroides nigromarginatus was
first described by a German scientist H. Meinken in 1957 as a new species base on a single specimen
collected from the ‘Ceylon’ without knowing exact locality. He had found that specimen among some exported ornamental fishes from Sri Lanka and considered it as a
synonymy of Rasboroides vaterfloris (Deraniyagala,
1958 & Pethiyagoda, 1991). It has not been collected since then until the rediscovery in 1994 from Athwelthota by R. Pethiyagoda & K. Manamendra Arachchi and
independently in 2010 by members of Wildlife
Conservation Society, Galle.
With the recent review of Rasboroides group it is now considered as a valid species occurs only in Athwelthota area of Kalu
river basin. Here we record a possible range extension of this species again on
Kalu river basin but considerable
distance away from the type locality. We
would like to keep exact locality undisclosed, considering past
experiences of extinction of some rare
endemic fish species from certain localities without proper protection, due to
excess collection for export and local ornamental fish industry (Ex. Extinction
of bright color Rasboroides species from Puwakpitiya Dola in Indikada Mookalana and total extinction of them from Madakada Mookalana - Chamikara S., 2012).
We were able to observe and photograph four live specimens of
Rasboroides in a tributary of Kalu
River in the Kiriella area of the Rathnapura district. The stream is bordered to a rubber plantation
but with well wooded banks with several indigenous plants. One specimen we observed was bit bigger than other three and lack black color of un-branched
ray of dorsal and other fins on the leading edge (However it is slightly
visible on the dorsal fin ray on nearly half of its length – See picture). But three small specimens had prominent black
lines along leading edge of all their fins. Other than that large specimen was more yellowish on its dorsal and upper half of the side and fins while small
specimens had more silver in dorsal as well as venter and sides. However orange red color of dorsal fin and
orange of caudal fin was not observed in any specimens. Taking accurate
measurements of the specimens was impossible with living fishes due to obvious
reason. But approximate size of the large specimen was visually estimated as
30mm and about 20mm of small three. Body
depth of all 4 specimens was around 30% SL.
Three out of four species of
Rasboroides have been recorded from Kalu
river basin and R. vaterifloris reported from Small shaded streams and rivulets
in and around Gilimale is the closet
Rasboroides locality recorded so far to the locality of the current specimens. However
morphological features of them much resembles to the R. nigromaginatus hitherto
only recorded from Athwelthota
area.
Is this a hybridization of R. nigromaginatus and R. vaterifloris? Why only small individuals have prominent black ray on leading edges of fins? Are they juveniles and would it be faded away in adult specimens? Or we are here dealing with two different species (We have observed that small individuals are schooling separately during our observation)? More research need to be done before come to a conclusion especially with exact measurements and scale counts with preserved specimens. But which is beyond our scope and for the time being we would like just to report this observation and highlight the need of conducting more research on our ichthyofauna and also most importantly conserving of their habitats with special consideration towards the streams and rivulets outside the protected forest reserves in Southwestern wet zone of the country. Because those water sources are highly vulnerable to the human activities (We got to known that excessive fishing have been practicing in above area some time even with using explosives which destroy every living inhabitants of the stream from big to small). There are enough possibilities of discovering new species not only of fishes but also other animals as well in these unprotected areas and it is needed to conserve them before those ‘to be discovered’ species would be vanishing from the world before even known to the scientific community.
Is this a hybridization of R. nigromaginatus and R. vaterifloris? Why only small individuals have prominent black ray on leading edges of fins? Are they juveniles and would it be faded away in adult specimens? Or we are here dealing with two different species (We have observed that small individuals are schooling separately during our observation)? More research need to be done before come to a conclusion especially with exact measurements and scale counts with preserved specimens. But which is beyond our scope and for the time being we would like just to report this observation and highlight the need of conducting more research on our ichthyofauna and also most importantly conserving of their habitats with special consideration towards the streams and rivulets outside the protected forest reserves in Southwestern wet zone of the country. Because those water sources are highly vulnerable to the human activities (We got to known that excessive fishing have been practicing in above area some time even with using explosives which destroy every living inhabitants of the stream from big to small). There are enough possibilities of discovering new species not only of fishes but also other animals as well in these unprotected areas and it is needed to conserve them before those ‘to be discovered’ species would be vanishing from the world before even known to the scientific community.
The Habitat of Rasboroides nigromaginatus(?)
R.
vaterifloris
|
R.
nigromaginatus
|
R. pallidus
|
R. rohani
|
|
Male –Upper
body color
|
Golden brown
lightening on side to silvery, scattered with melanophores
|
Golden
orange, sides and venter silver
|
Dorsal color
varies from pinkish-grey to dark golden yellow, lighter latterly. Silver on
venter
|
Dorsally
greyish-yellow, golden yellow on sides and silvery-white on venter.
|
Male- belly
|
Silver
|
Silver
|
Silver
|
|
Dorsal Fin
|
Hyaline with
scattered melanophores
|
Orange red, Longest
un-branched dorsal fin ray black along its entire length.
|
Golden yellow
|
Golden yellow
|
Anal fin
|
Hyaline with
scattered melanophores
|
Yellow with
scattered melanophores. Unbranched rays of leading edge black
|
Golden yellow
|
Yellow-orange
|
Pectoral fin
|
Hyaline with
scattered melanophores
|
Yellow with
scattered melanophores. Unbranched rays of leading edge black
|
Golden yellow
|
Golden yellow
|
Pelvic fin
|
Hyaline with
scattered melanophores
|
Yellow with
scattered melanophores. Unbranched rays of leading edge black
|
Golden yellow
|
Golden yellow
|
Caudal fin
|
Greenish
Yellow
|
Orange.
|
Lighter with
upper lobe hyaline
|
Yellow-orange
on lower lobe. Upper lobe hyaline.
|
Sclera
|
Upper third
of sclera deep Orange
|
Dense melanophores
on sclera above and below giving effect of black bar on eye (Bothe M and F)
|
||
Opercle
|
Suffused with
dark red (Bothe M and F)
|
|||
Female
|
Similar to
male but lighter in color, yellowish tan dorsally whitish with scattered
melanophores on sides, belly white
|
Similar but
lighter in color. Lacking black dorsal and anal fin margins and yellowish tan
dorsally. Whitish with scattered melanophores on sides, , belly white
|
Overall light
whitish orange. Lighter ventrally and on fins, which are partly hyaline
|
Sexes alike
|
Fins
|
Pectoral fin
reaching beyond pelvic fin base; pelvic fin reaching beyond anal fin origin.
Dorsal fin origin located halfway between snout-tip and hypural notch.
|
Pectoral fin
reaching beyond base of pelvic fin; pelvic fin reaching beyond origin of anal
fin; Dorsal fin origin located halfway between snout-tip and hypural notch.
|
Pectoral fin
reaching base of pelvic fin; pelvic fin reaching origin of anal fin. Dorasl
fin origin located halfway between snout-tip and hypural notch.
|
Pectoral fin
reaching base of pelvic fin; pelvic fin reaching origin of anal fin. Dorasl
fin origin located halfway between snout-tip and hypural notch.
|
Dorsal fin
origin
|
1 scale width
behind the pelvic fin origin
|
1 scale width
behind the pelvic fin origin
|
3 scale width
behind the pelvic fin origin
|
3 scale width
behind the pelvic fin origin
|
Pelvic fin
origin
|
Midway
between pectoral fin base and anal fin origin
|
Closer to
anal fin origin than to pectoral fin base.
|
Falling
midway between pectoral fin base and anal fin origin
|
Closer to
anal fin origin than to pectoral fin base
|
Dorsal margin
of the operculum
|
More or less
straight
|
Deep
indentation
|
||
Dorsal
profile of the head
|
Approximately
straight behind the level of the eye in the male
|
Slightly
concave
|
Slightly
concave behind level of eye, arched thereafter
|
Approximately
straight posterior to level of eye
|
Male Interorbital
width
|
29-33 % HL
|
17-22 % HL
|
||
Male Internarial
width
|
19-21 % HL
|
11-17 % HL
|
||
Female anal
fin depth
|
23.5-24.8 % SL
|
17.4 – 22.7 %
SL
|
||
Female interorbital
width
|
25-33 % HL
|
16-21 % HL
|
33-36%HL
|
25-28 % HL
|
Female Caudal-peduncle depth
|
12.4 – 13.4 %
SL
|
10.4 – 12.3 %
SL
|
||
Female Caudal-peduncle length
|
18.6-21.2% SL
|
21.1-25 % SL
|
||
Body depth
|
31-32.8 % SL
( 31.1-32.8 in males and 31 – 31.7 in females)
|
26.9-33% SL
(28.2-33 in males and 26.9-29.1 in females)
|
34.3-37.5%SL
of males and 33-36.7in females
|
35.6 -40% SL
in males and 33.3-36.8 % SL in females
|
Size
|
Male –
23.9-29.8mm Female – 22.1 – 25.5mm
|
Males 26.2 –
30.2 Female – 26.5 – 27.3mm
|
Up to 24.6 mm
SL (males 21.5-24.6 and females 20.2- 20.7)
|
Up to 35.5mm
SL (Males 25.3-35.5 and Females 23-30.8)
|
Scales on
transverse line on the body
|
½ 8 ½
|
½ 8 ½
|
½ 6 ½ or ½ 7
½ ( ½ 6[3] or 7 ½ [12] )
|
½ 8 ½
|
Scales on caudal
peduncle
|
½ 4 ½
|
½ 4 ½
|
½ 3 ½
|
½ 4 ½
|
Predorsal
scales
|
10[2],11[6],12[2]
|
11[4] or
12[6]
|
10[7],11[5],12[3]
|
11[5],12[6],13[4]
|
Prevental
scales
|
15[2] or
16[8]
|
14[2], 15[7],
16[3]
|
13[7],14[4],15[2]
|
14[3],15[9],16[3]
|
Abdominal
vertebrae
|
12[1] or
13[1]
|
12
|
11[4], 12[1],
13[1]
|
12
|
Caudal
vertebrae
|
16[1] or
17[1]
|
16
|
16[2] or
17[4]
|
17
|
Total
vertebrae
|
29
|
28
|
28-29
|
29
|
Scales on
lateral series on body
|
21[2],22[1],23[1],24[5],25[1]
|
23[1],24[1],25[7],26[2],27[1]
|
20[1], 21[1], 22[7],23[0],24[6]
|
25[3],26[8],27[1],28[3]
|
Perforated
scales arterially
|
4[3],5[2],6[5]
|
1[1],2[5],3[7]
|
1[11] or 2[4]
|
1[6],2[3],3[5]
|
Lateral
processes to the kinethmoid
|
2
|
1
|
||
Female eye
diameter
|
39 – 40% HL
|
29-34 % HL
|
||
Pharyngeal-teeth
formula
|
5,4,3-3,4,5
|
5,4,3-3,4,5
|
5,4,3-3,4,5
|
5,4,2 -2,4,5
|
Dorsal fin
rays
|
3 unbranched
and 7 ½ bracnched
|
3 unbranched
and 7 ½ bracnched
|
3 unbranched
and 7 ½ bracnched
|
3 unbranched
and 7 ½ bracnched
|
Anal fin rays
|
3 unbranched
and 5 ½ [2] or 6 ½[8] branched
|
3 unbranched and
6 ½ branched
|
3 unbranched
and 6 ½ branched
|
3 unbranched
and 6 ½ branched
|
Caudal fin
rays
|
17 branched
rays 9 on upper and 8 on lower lobes
|
17 branched
rays 9 on upper and 8 on lower lobes
|
17 branched
rays 9 on upper and 8 on lower lobes
|
17 branched
rays 9 on upper and 8 on lower lobes
|
Pectoral fin
rays
|
1 unbranched
and 11 ½ [4] or 12 ½ [6] branched
|
1 unbranched
and 11 ½ branched
|
1 unbranched
and 11 ½ branched
|
1 unbranched
and 11 ½ branched
|
Pelvic fin
rays
|
1 unbranched
and 6 ½ [3] or 7 ½ [7] branched
|
1 unbranched
and 6 ½ branched
|
1 unbranched
and 6 ½ branched
|
1 unbranched
and 6 ½ branched
|
Lateral line
|
Incomplete
|
Incomplete
|
Incomplete
|
Incomplete
|
Distribution
|
Restricted to
Kalu basin. Small shaded streams and rivulets in and around Gilimale. Type
locality – Ilukwaththa ferry of Kalu river at Gilimale
|
Restricted to
the Athwelthota of Kalu basin
|
Shallow slow
flowing densely shaded low land rain forest streams with sandy silt
substrates of Kalu (Mahakalupahana, Yagirala), Benthara(Bambaravana), Gin
(Kottawa-Kombala FR)Polathu-Modara (Kottawa-Kombala FR), Nilvala (Dediyagala
FR) basins.
|
Suriyakanda
in Walawe river basin. Shallow slow flowing shady streams with a sandy-silt
substrates and dense leaf litter in submontane forests.
|
Literature Cited
Batuwita S., de Silva M. and Edrisinghe U., 2013. A review of the danionine genera
Rasboroides and Horadandia (Pisces: Cyprinidae), with description of a new
species from Sri Lanka Ichthyol. Exploe. Freshwaters, Vol. 24, No. 2, 121-140
pp.
Chamikara S., 2012. පාට වර්ණ කොහි ගියාද හල්මල් දන්ඩියනේ? - සදාහරිත වෙළුම 1 කලාපය 9
Deraniyagala, P.E.P.1958. Three new cyprinoids, a new catfish
and variation among some cyprinoids and an anabantoid of Ceylon. Spolia
Zeylanica, 28: 129-138.
Meinken, H. 1957. Rabora nigromarginata n. spec. die
"Rote rasbora". Die Aquarien - und Terrarien Zeitschrift, 10: 65-68.
Pethiyagoda, R. 1991. Freshwater fishes of Sri Lanka.
Wildlife Heritage Trust, Colombo, xiii+362pp.
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