Microrasbora Annandale, a new genus record in China, with description of a new species (Teleostei: Cyprinidae)

Abstract

A new species of genus Microrasbora Annandale (1918), M. microphthalma, is described from the Nanwan River, a tributary of the Ruili River, Irrawaddy drainage, in southwest Yunnan province, China.
This new species is the first record of the genus Microrasbora in China. Microrasbora microphthalma can be distinguished from the other species of Microrasbora by the following combination of characters: 15–16 predorsal scales, eye diameter/head length 27–38%, eye diameter/interorbital
width 70–93%, predorsal length/ standard length 60–68%, the preanal length/ standard length 65–71% and the origin of dorsal
fin is posterior of that of the ventral fin.

Full text

Microrasbora Annandale, a new genus record in China,
with description of a new species (Teleostei: Cyprinidae)
Yan-E. Jiang &Xiao-Yong Chen &Jun-Xing Yang
Received: 9 September 2007 / Accepted: 28 January 2008 / Published online: 6 March 2008
#Springer Science + Business Media B.V. 2008
Abstract A new species of genus Microrasbora
Annandale (1918), M. microphthalma, is described
from the Nanwan River, a tributary of the Ruili River,
Irrawaddy drainage, in southwest Yunnan province,
China. This new species is the first record of the
genus Microrasbora in China. Microrasbora micro-
phthalma can be distinguished from the other species
of Microrasbora by the following combination of
characters: 15–16 predorsal scales, eye diameter/head
length 27–38%, eye diameter/interorbital width 70–
93%, predorsal length/ standard length 60–68%, the
preanal length/ standard length 65–71% and the origin
of dorsal fin is posterior of that of the ventral fin.
Keywords Taxonomy .Habitat .
Microrasbora microphthalma .China
Introduction
The genus Microrasbora (Cyprinidae: Danioninae)
was established by Annandale in 1918 with M.
rubescens (type species) and M. erythromicron.M.
erythromicron was thought not belong to Micro-
rasbora and was put into the genus Danio according
to Kottelat and Witte (1999). M. erythromicron may
be congeneric with Celestichthys margaritatus by
Roberts (2007). Rasbora maculate (Duncker 1904)
and R. heteromorpha (Duncker 1904) were tentatively
put into the genus Microrasbora by Annandale, but
never been considered as members of Microrasbora
(Kottelat and Witte 1999). In 1993, R. maculate was
transferred to the genus Boraras by Kottelat and
Vidthayanon. And R. heteromorpha was put into
genus Trigonostigma by Kottelat and Witte (1999).
Herre (1939) described Microrasbora gatesi which
was collected from Rangoon and Hlegu, Irrawaddy
drainage, Myanmar. Microrasbora nana and M.
kubotai were described by Kottelat and Witte
(1999). Microrasbora nana was collected from
Sittang River basin, and M. kubotai from Ranong
Province, Thailand.
The genus Microrasbora can be distinguished from
other genera of Danioinae or Rasborinae by the
following characters: body rather short and strongly
compressed; eyes large and prominent, the diameter
of the eye is about 1.5 times in interorbital width.
Mouth small and oblique, almost semicircular; lower
Environ Biol Fish (2008) 83:299–304
DOI 10.1007/s10641-008-9336-8
Xiao-Yong Chen and Jun-Xing Yang contributed equally to this
paper.
Y.-E. Jiang :X.-Y. Chen (*):J.-X. Yang
Department of systematic Zoology,
Kunming Institute of Zoology,
Chinese Academy of Sciences,
32 Jiao Chang Dong Road,
Kunming, Yunnan 650223, People’s Republic of China
e-mail: chenxy@mail.kiz.ac.cn
Y.-E. Jiang
Graduate School of Chinese Academy of Sciences,
10039, Beijing, People’s Republic of China

jaw without any symphysial prominence (process).
No barbels. Pharyngeal bone with two or three rows
of teeth. Dorsal fin inserted in advance of anal fin,
with 8–10 (5–7 branched) rays, simple rays non-
osseous; Anal fin with eight to 13 branched rays.
Caudal fin strongly forked. Scales very large, thin, not
easily discernible, deciduous, lateral line absent.
(Talwar and Jhingran 1991).
At present, there are four valid species in genus
Microrasbora,Microrasbora rubescens,M. gatesi,M.
kubotai and M. nana.
In November 2006, a diminutive fish was collected
in Nanwan River, a tributary of Irrawaddy drainage,
Yunnan, China. By this study, it is proved to be an
undescribed species, is described as a new species and
new genus record herein, and is compared with the
other four species of the genus.
Material and methods
Type specimens of Microrasbora microphthalma are
deposited in Kunming Institute of Zoology (KIZ),
Chinese Academy of Sciences (CAS). The specimens
of other species of this genus is not available for this
study, so only literature were used for comparison.
Counts and measurements followed Hubbs and
Lagler (2004). Counts and measurements were taken
from the left side of the specimens if possible.
Measurements were made with digital dial calipers
and recorded to 0.1 mm. Vertebrate number from one
boned specimen. Data of the water by WTW Multi
3501. Abbreviations used in this study are: standard
length (SL), total length (TL), body depth (BD), head
length (HL), head depth (HD), eye diameter (ED),
caudal-peduncle length (CPL), caudal-peduncle depth
(CPD), interorbital width (IOW), predorsal length
(Predl), preventral length (Prevl), preanal length
(Preal), body weight (BW).
Results
Microrasbora microphthalma, sp. nov. (Fig. 1). Ho-
lotype: KIZ 2006003337, 19.0 mm SL, 0.15 g BW,
Nanwan River (a tributary of upper Irrawaddy), 1 km
from Simenkan Village, Qingping Township, Long-
chuan County, Yunnan Province, China. 24°16′32.5″N
97°54′06.6″E, 946 m; Chen XY, Du LN, Jiang YE and
Liu C, November 2006. Paratypes: KIZ 2006003323-
2006003336, 15 specimens, 14.9–25.7 mm SL, 0.06–
0.25 g BW, collected with the holotype.
Diagnosis
Microrasbora microphthalma is distinguished from
the other species of the genus Microrasbora by the
following characters: 15–16 pre-dorsal scales, the pre-
dorsal length is 60–68% of standard length, the pre-
anal length is 65–71% of standard length, the eye
diameter is 27–38% of head length, and 70–93% of
inter-orbital width., the dorsal origin is posterior of
that of the pelvic fin.
Microrasbora microphthalma is different from M.
rubescens in number of branched pectoral-fin rays
and predorsal scales (Table 1). The origin of dorsal fin
is posterior to that of the pelvic fin in M. micro-
phthalma vs. slightly in advance of that in M.
rubescens.
Microrasbora microphthalma is different from M.
gatesi in ED/HL, ED/IOW, HL/IOW, branched
dorsal-fin rays, anal branched fin and predorsal scales
(Table 1). The body is grizzly white in M. micro-
phthalma, but very pale yellowish in M. gatesi. There
are black dots on fins except pelvic fin in M.
microphthalma, but only soft dorsal rays speckled
with minute black dots (Herre 1939)inM. gatesi.
Microrasbora microphthalma is different from M.
kubotai with BD/SL, ED/HL, branched caudal-fin and
predorsal scales (Table 1). The body is grizzly white
in M. microphthalma, but yellowish in M. kubotai.
And a few black pigments over hypural complex
(Kottelat and Witte 1999)inM. kubotai, but no
pigments there in M. microphthalma.
Fig. 1 Microrasbora microphthalma, holotype, KIZ
2006003337, 19.0 mm SL, Nanwan River, Qingping township,
Longchuan county, Yunnan, China
300 Environ Biol Fish (2008) 83:299–304

Microrasbora microphthalma is different from M.
nana with HD/HL, ED/HL, Preal/SL, branched
caudal-fin and predorsal scales (Table 1). The color
in life is brownish gray in M. microphthalma, but
slightly yellow with iridescent blue sides and silvery
eyes and belly (Herre 1939)inM. nana. A black
blotch at tip of last simple and first two branched
dorsal-ray, and a fainter blackish blotch at tip of last
simple and first 3–4 branched anal rays (Kottelat and
Witte 1999)inM. nana, but not in M. microphthalma.
Description
General appearance is shown in Fig. 1. Counts and
proportional measurements are shown in Table 1. Body
elongate and compressed. Dorsal origin is posterior to
that of pelvic fin, distinctly nearer caudal base than
snout-tip. Fold pectoral fin not reaching the origin of
ventral. Ventral fin not reach anal origin, and ventral
fin closer to anal origin than that of pectoral. Base of
anal fin closer to that of pelvic fin than to caudal.
Table 1 Counts and morphometric characters of Microrasbora fishes
M. microphthalma M. nana
a
M. kubotai
a
M. rubescens
b
M. gatesi
c
n=16 n=5 n=6 n=1 n=17
Total length (mm) 17.0–33.4 (25.1; 4.2)
Standard length (mm) 14.9–25.7 (20.2; 2.8) 13.9–15.2 7.5–19.0 30.0 16.0–23.0
Dorsal–fin rays III, 7–8 III, 7 II–III, 7 II, 6–7 III, 5–6
Anal-fin rays III, 9–10 III, 10–11 III, 9–10 III, 10–12 III, 12–13
Pectoral-fin rays I, 9–10 10–12 10–11 11 I, 10
Pelvic-fin rays I, 5–7 6 7 7 I, 6
Caudal branched rays 10+ 10 9+ 8 9 + 8 26
Predorsal scales 15–16 11–13 10–11 12–14 12–14
Longitudinal scales 24–27+ 1–225–26+1–224–25+ 1(3) 28–30 + 1–226–28+1–2
Circumpeduncle scales 4 0.5–4–0.5 0.5–4–0.5
Vertebrae 12+18 12–13+17–18 13+ 16
Percentage of SL (%)
TL 114.0–130.0 (124.0; 4.7) 129.0–140.3
HL 25.0–31.0 (28.0; 1.7) 23.0–23.8 26.7–28.8
Predorsal length 60.0–68.0 (63.0; 2.3) 54.5–58.8 54.4–58.6
Prepelvic length 46.0–54.0 (51.0; 2.2) 47.4–49.1 47.7–50.0
Preanal length 65.0–71.0 (68.0; 1.8) 59.4–61.8 60.6–63.4
BD 22.0–29.0 (25.0; 2.0) 25.3–29.6 30.0–34.6
CPD 8.0–13.0 (11.0; 1.3) 11.8–14.2 12.5–14.4
CPL 16.0–23.0 (20.0; 1.8) 21.9–24.8 20.1–24.4
Percentage of TL (%)
HL 20.0–26.0 (22.0; 0.0) 25.0
CPL 12.0–20.0 (16.0; 1.2)
CPD 7.0–10.0 (9.0; 0.0) 11.0
Percentage of HL (%)
HD 67.0–79.0 (73.0; 3.3) 90.0–98.0 73.0–79.0
SNL 22.0–31.0 (27.0; 0.0) 18.0–22.0 21.0–25.0 21.0–23.0
ED 27.0–38.0 (34.0; 2.6) 39.0–43.0 42.0–48.0 40.0–42.5
Percentage of IOW (%)
HL 203.0–285.0 (243.0; 0.2) 256.0–303.0 208.0–238.0 360.00
ED 70.0–93.0 (82.0; 0.1) 146.0–156.0
Percentage of CPD (%)
CPL 126.0–238.0 (179.0; 0.3) 150.0–200.0 160.0–190.0
a
From Kottelat and Witte (1999)
b
From Annandale (1918), some data were converted to fit the table
c
From Herre (1939), some data were converted to fit the table
Note: The mean and SD (standard deviation) are in parentheses
Environ Biol Fish (2008) 83:299–304 301

Head is short and its dorsal profile slightly convex.
Snout is blunt and rounded. Mouth is small and there
are no tubercles on the lower jaw.
Scales thin and transparent. lateral line absent.
Anus close to anal-fin origin. Pharyngeal teeth three
rows, teeth pattern is 542–245. Vertebrae 12+18,
from one specimen KIZ 2006003323.
Coloration of living specimens The color of body is
brownish gray. A black midlateral stripe from back of
operculum to base of caudal fin. And a silvery stripe
from anterior axis of anal fin to base of caudal fin.
Operculum, eyes and suborbital area silvery. Bases of
pectoral, pelvic and anal fins yellowish red.
Coloration in preservation (75% ethanol) (Fig. 1)
The body is grizzly white with a black interaxial
stripe. The stripe is more diffuse anteriorly where
melanophores are more scattered; it ends shortly
before base of caudal fin. Dots are on the part above
interaxial strip at both sides of specimen. A black
pentagonal spot is found in the front of nape, and
behind it a black stripe along the median line of the
back, from head to tail. A few scattered pigments are
on all rays of fins except pelvic fins. Operculum, eyes
and area under eyes are silvery white. There is a row
of black pigments at the top of eye socket.
Distribution
Present known from the Nanwan River, a tributary of
the Ruili River, Yunnan Province, China (Fig. 2).
Etymology
From the Greek, micro means small. ophthalm, from
opthalmos,Greek, means eyes. microphthalma refer
to relative smaller eyes when compared to its congers,
gender feminine.
Habitat and ecology
All individuals of M. microphthalma were collected
in one site on the Nanwan River, 1 km from
Simenkan village, a right bank tributary of the Ruili
river. The Nanwan River is a small hill stream, with
sandy bottom and numerous cobblestones (about
100 mm in diameter). The width of the stream is
about 5 m, water depth is 0.80 m, and the water
transparency is 0.44 m. The temperature of the stream
is 20.3°C, the pH value of the stream is 6.80. Water
velocity in the middle of the stream is 0.99 m s
−1
(Gong et al. 2005).
There is a wooden fence in the left side of the river.
And M. microphthalma was collected from the place
between the bank and the fence. The wooden fence is
approximately 1 m long and 1 m high, about 0.20 m
out of the water, and 0.50 m far away from the bank.
Several other species of fish were collected at the same
time: Danio albolineata (Cyprinidae), Pseudorasbora
parva (Cyprinidae), Puntius ticto (Cyprinidae),
Abbotina rivularis (Cyprinidae), Lepidocephalichthys
hasselti (Cobitidae), Gambusia affinis (Poeciliidae),
Tilapia aureus (Cichlidae), Channa gachua (Channi-
dae). All of these species were collected by handnet.
Zooplankton, phytoplankton and sand were found
in the intestines of M. microphthalma. The phyto-
planktons of diatoms are Gomphonema,Cymbella,
Navicula,Achnanthes,Diatoma and Closterium.
Discussion
Microrasbora microphthalma is the first species of
the genus Microrasbora which has been found in
China, from the Irrawaddy river drainage. Only M.
gatesi and M. microphthalma occur in Irrawaddy
drainage. Microrasbora rubescens occurs in Salween
and M. nana in Sittang drainages. Microrasbora
kubotai is known in the western slope of Peninsular
Thailand (Kottelat and Witte 1999).
Microrasbora microphthalma is the northmost in
distribution and M. kubotai the southmost, while the
other three species are almost live in the same
longitudinal area. It makes genus Microrasbora a
group almost confined in China–Myanmar–Thailand
region with Myanmar the distribution center.
Microrasbora species share some characters. M.
kubotai and M. nana share the following characters: 7
branched dorsal fin rays, 9+ 8 branched caudal fin rays,
0.5–7–0.5 horizontal scale, 0.5–4–0.5 scale around
caudal peduncle and absence of lateral line. M. nana,
M. rubescens and M. gatesi share the same 6 branched
pectoral fins. Both M. kubotai and M. microphthalma
have 9–10 branched anal-fin. M. rubescence and M.
gatesi have 12–14 predorsal scale. M. rubescens and
302 Environ Biol Fish (2008) 83:299–304

M. microphthalma share the same character, pectoral
fin not reaching pelvic fin. Both M. microphthalma and
M. nana without tubercles on lower jaw.
Key to species of Microrasbora
1(8) No black blotch at tip of dorsal fin and no
grayish blotch at the tip of anal fin.
2(7) 25–30+1–2 scales in longitudinal series; 12–17
pre-dorsal scales; 8–14 branched anal-fin rays
3(6) 12–14 pre-dorsal scales, 10–14 branched anal-fin
rays
4(5) 10–12 branched anal-fin rays, anal papilla
black……………………….……M. rubescens
5(4) 13–14 branched anal-fin rays, anal papilla not
distinctly colored………………..…M. gatesi
Fig. 2 Type distribution
of Microrasbora fishes
(empty square M.
microphthalma;filled circle
M. kubotai;filled pentagon
M. gatesi;filled square M.
rubescence;✹M. nana)
Environ Biol Fish (2008) 83:299–304 303

6(3) 14–17 pre-dorsal scales, 8–9 branched anal-fin
rays………………………..M. microphthalma
7(2) 24–25+1 scales in longitudinal series; 10–11
pre-dorsal scales; 9–10 branched anal-fin
rays…………………………….M. kubotai
8(1) A black blotch at tip of dorsal fin and grayish
one at the tip of anal fin…M. nana
Acknowledgments We are deeply indebted to Du Lina
and Liu Chun for help collecting specimens. Thanks are given
to Maurice Kottelat for providing papers related to this
study. The authors are grateful to Yang Jian and Holly
Barclay who helped improve the manuscript. This work was
funded by the National Basic Research Program of China (973
Program) (2007CB411600), the National Basic Research
Program of China (2003CB415103), the National Natural
Science Foundation of China (30730017) and Major Research
Plan of National Natural Science Foundation of China
(90411002).
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