A new fish species is discovered and scientifically named

1. Mystus indicus and M. heoki, two new catfishes from Kerala, India
MATHEWS PLAMOOTTIL AND NELSON P. ABRAHAM
Asst. Professor, Govt. College Chavara, Kollam Dt., Kerala, India
Associate Professor, St.Thomas College, Kozhencherry, Pathanamthitta Dt., Kerala, India
ABSTRACT - Mystus indicus, a new species of the family Bagridae, is described from Kuttoor of Manimala
River in Kerala, India. It is distinguished from its congeners by the following combination of characters: snout
longer; median groove on head appear as double cephalic fontanels; occipital process reaches to basal bone of
dorsal fin, on both sides of occipital process a thick layer of flesh present, which conceals the former from side
view; rayed dorsal base prominently swollen on both sides. Mystus heoki, new species, differs from its relative
species in having a markedly elongate body, shorter head and smaller eyes; occipital process short and it never
reach basal bone of dorsal fin and the former is not visible as it is concealed under a thick layer of flesh; adipose
dorsal fin small, its base short, and it is located fairly away from rayed dorsal fin. The new species of fishes are
described and compared with related species.
KEYWORDS – Manimala River, taxonomy, new description, Mystus malabaricus.
urn:lsid:zoobank.org:pub:31DEDA60-E850-49DD-A818-4A2894FF6219
urn:lsid:zoobank.org:act:FC8365F6-B11D-4C4E-A7CC-A6B8334CF2F3
urn:lsid:zoobank.org:act:FC8365F6-B11D-4C4E-A7CC-A6B8334CF2F3
Introduction
Catfishes constitute a large group of chiefly fresh water
fishes distributed around the world. Africa, India and
SouthAmerica are rich in quantity and species diversity
of catfishes. Rita, Sperata, Mystus, Hemibagrus,
Horabagrus, Rama, Chandramara and Batasio are
the bagrid cat fish genera found in India (Misra, 1976;
Talwar & Jhingran, 1991; Jayaram & Sanyal, 2003;
Jayaram, 2006); of these Mystus, Hemibagrus,
Horabagrus and Batasio alone are known from inland
water bodies of Kerala.
Mystus is the most common genus in India,
especially in Kerala. The fishes of this genus though not
growing to large size, excepting a few, provide by
numbers the required protein to the masses (Jayaram &
Sanyal, 2003). Mystus vittatus, M. oculatus, M.
montanus, M. malabaricus, M. armatus, M.
canarensis and M. gulio are the major Mystus species
of Kerala (Misra, 1976; Easa & Shaji, 2003; Jayaram &
Sanyal, 2003; Jayaram, 2006, 2010).
Biosystematica
ISSN: 0973-7871(online)
ISSN: 0973-9955 (print)
Biosystematica, 2013,7(1): 43-58
43
© Prof. T.C. Narenderan Trust for Animal Taxonomy
http://www.tcntrust.org/journal.php
Corresponding author: mathewsplamoottil@gmail.com
The first author could collect eight specimens of
Mystus species from Kuttoor of Manimala River in
Kerala, India and other different six specimens of this
genus from Elankadu of the same river; these bagrid
fishes bear features of the genus but carry enough
characters to distinguish from their congeners; so they
are described here as two new species Mystus indicus
and M. heoki respectively.
Materials and methods
Fishes were collected using cast nets and preserved in
10% formalin. Identification of various Mystus species
was carried out following Jerdon (1849), Day (1865, 1877
& 1889), Misra (1976), Jayaram & Sanyal (2003) and
Jayaram (2006 & 2010). Methods used are those of
Jayaram (2002) and measurements follow standard
practices. Body depth and body width were measured
both at dorsal-fin origin and anus, vertically from dorsal-
fin origin to belly and from anus to dorsum, respectively.
Abbreviations: ZSI- Zoological Survey of India,
Kolkata, West Bengal; ZSI/SRC- Zoological Survey of

2. Biosystematica, 2013, 7(1)
44
India, southern regional centre, Chennai, Tamil Nadu;
ZSI/WGRC- Zoological Survey of India, Western Ghats
regional centre, Calicut, Kerala; KFRI- Kerala Forest
Research Institute, Peechi, Kerala; STC/DOZ- St.
Thomas college, Department of Zoology; TL- total
length; SL- standard length; HL- head length; BDD-
body depth at dorsal fin origin; HD- head depth; RD-
rayed dorsal fin; AD- adipose dorsal fin; LBA- length
of base of anal fin; LBAD- length of base of adipose
dorsal fin; LBRD- length of base of rayed dorsal fin;
LCP- length of caudal peduncle; DCP- depth of caudal
peduncle; CL- caudal lobe; DspT- dorsal spine teeth;
PspT- pectoral spine teeth; HT- holotype; PT- paratype.
Mystus indicus, sp. nov
( Fig. 1 & 2; 6. G, 7. G & Table 1, 3 & 4)
urn:lsid:zoobank.org:act:CE0E1E2C-0BCC-464A-
ACE0-00AA97D1192F
Materials Examined
Holotype: ZSI/FF 4627, 100 mm SL, Kuttoor, Manimala
River, Kerala, India; collected by Mathews Plamoottil,
17 February 2011.
Paratypes: ZSI/WGRC/2418, 7 specimens, 81- 107 mm
standard length, Kuttoor of Manimala River, Kerala,
India; collected by Mathews Plamoottil, 07 March 2011.
Diagnosis: The new species can be differentiated from
all its relative species in having an elongated snout, a
thick layer of flesh present on both sides of occipital
process, pectoral spine with more teeth, greater pre pelvic
length, rayed dorsal fin base prominently swollen on both
sides and wide caudal peduncle. Mystus indicus can
be differentiated from M. montanus in having double
median cephalic fontanels (vs. a single median
longitudinal groove), pectoral fin with 6- 8 branched rays
(vs. 6 branched rays) and lesser pre dorsal length (30.8-
36.0 % SL vs. 39.1- 43.8). The new species differs from
Mystus armatus in having pectoral fin with 6-8 branched
rays (vs. 9), caudal fin with 15- 17 rays (vs. 19) and
median longitudinal groove on head shallow and wide
(vs. narrow and moderately deep). The new species
differs from Mystus oculatus in having a cephalic
fontanel which never reach occiput (vs. fairly reach
occiput in M. oculatus), 7- 8 branched rays in anal fin
(vs. 9- 10), and longer adipose dorsal fin base (26.2-
33.7 % SL vs. 17.2- 19.0). The new species differs
from Mystus malabaricus and M. canarensis in having
occipital process reaching basal bone of dorsal fin (vs.
never reach) and occipital process naked and visible (vs.
a thick flesh covers occipital process and so it is invisible).
Description: Body elongate, compressed. Head
depressed, head length 5.0- 5.7 in total length and 3.8-
4.5 in standard length; head width 68.0- 83.3 and snout
length 36.2- 42.5 in percent of head length. Body height
at dorsal origin 5.0- 6.8 in total length and 4.0- 5.3 in
standard length; ventral profile of the body more convex
than dorsal profile. No considerable rise in the profile
from snout to base of first dorsal fin. Dorsal surface of
head rough; occipital process rugose with granulated
lines; opercle rough with radiating lines; shoulder bone
rather longer than deep at its base with rough lines. Eyes
with free orbital margins, 3.6- 4.2 in head, 1.3- 1.7 in
snout and interorbital width. Greatest width of the head
greater than its length behind the angle of mouth. Mouth
sub terminal, transverse, upper jaw longer, its gape width
34.8- 40.9 in percent of head length. Maxillary barbels
reach to posterior end of anal fin base, outer mandibulars
reach considerably behind half way between pectorals
and pelvics, inner mandibulars reach middle of pectoral
base and nasals extend to occiput. Nasals located nearer
to snout than orbit. A prominent depression present
between nasal barbels. Median longitudinal groove on
head shallow, wide and appear as two fontanels, reaching
fairly behind orbit mostly near to occiput. Occipital
process reaches to basal bone of dorsal fin; on both sides
of the former a thick layer of flesh present, which
conceals the occipital process from side view but it never
cover the occipital process. Teeth villiform in band in
jaws. A prominent depression present on the humeral
region of the body.
Rayed dorsal fin, 1.1- 1.7 in head, arises at 1/2 to
1/3 of length of pectoral from its anterior end, nearer to
adipose dorsal origin than to snout end; its tip reaches
origin of adipose dorsal, above at or behind the middle
of ventral fin. Outer margin of dorsal fairly convex.
Only a little space present between rayed dorsal and
adipose dorsal; inter dorsal space considerably shorter
than rayed dorsal base. Rayed dorsal base, 1.6- 2.5 in
adipose dorsal base, prominently swollen on both sides,
mostly flesh colored. Dorsal spine, 1.6- 2.2 in head
length, osseous, moderately strong; posterior half of its
inner surface serrated, outer side smooth. Adipose dorsal
originates a little behind rayed dorsal base and above
middle of ventral and fairly in front of anal origin; its
height 5.2- 6.5 and its base 26.2- 33.7 in percent of
standard length.
Pectorals, 1.3- 1.6 in head, low, not reaching pelvic
fin, with a strong spine, 1.4- 1.7 in head and with 16
strong denticulations, of which 7 or 8 teeth more
pronounced in the terminal half. Base of pectoral is
slightly fleshy. Ventral, 1.4- 1.8 in head, arises just
PLAMOOTTIL &ABRAHAM

3. Biosystematica, 2013, 7(1)
45
below the last dorsal ray or a little in front of it, near to
anal fin than pectoral fin base; its tip never reaches anal
fin, but reaches anal opening and its outer margin slightly
convex; its base swollen and light red colored. Anal fin,
1.6- 2.4 in head, originates a snout length behind adipose
dorsal origin, near to pelvic fin origin than caudal base
and its tip reach anal papilla; its outer margin convex.
Length of base of anal fin 1.9- 3.1 in adipose dorsal
base. Tips of caudal lobes pointed; upper lobe the longer;
least height of caudal peduncle 1.3- 1.7 in its length.
Skin smooth. Lateral line proceeds to extreme tip
of caudal peduncle. Lateral line and sense organs on it
clearly visible. Body muscles are distinctly seen on
lateral sides of body.
Coloration: Upper lateral sides yellowish green; lower
lateral sides white; rayed dorsal, adipose dorsal and anal
fin greenish yellow; caudal hyaline; its base light yellow;
a thin bluish black line passes through lateral line; light
grayish indistinct bluish black spot present on humeral
and caudal regions. One to two anterior dorsal rays,
ventral and anal fins with a light black shade. Eyes
bluish.
Distribution. - Currently known only from the type
locality in Kerala.
Habitat. – Manimala River at Kuttoor, the type locality
of Mystus indicus, is floored by means of gravelly sand
dominated sediments. River width varies between 50
m and 125 m; the depth ranges from 1 m to 15 m and
river bank height varies between 0.5 and 1.5 m. This
stretch of the river contains many pools, including Kalleli
kadavu with a depth of 15 m, most of them are formed
by illicit and indiscriminate scooping of sand. A major
portion of the river is covered by moderately developed
riparian vegetation. The major species in the riparian
flora include Bambusa bambos, Bambusa vulgaris and
Ochreinauclea missionis. The varities that occur in
minor proportions comprise Hibiscus tiliaceus, Ficus
glomerata, Hydnocrpus pentandra, Holigarna
arnottiana ,Pongamia pinnata, Ficus exasperata and
Tribulus terrestris. Anquilla bengalensis, A. bicolor,
Barilius bakeri, Danio malabaricus, D.
aequipinnatus, Salmostoma boopis, Rasbora
daniconius, Puntius vittatus, Dawkinsia filamentosa,
Haludaria fasciata, Pethia ticto, Horabagrus
brachysoma, Mystus gulio, Mystus armatus,
Heteropneustus fossilis, Clarias dussumeiri, Etroplus
suratensis, Etroplus maculatus, Oreochromis
mossambica, Mastacembelus armatus,
Macrognathus guentheri etc are the co- occurring fish
species.
Etymology. – Species name refers to the country from
which it was described firstly. Latin word “indicus”
means ‘of India’.
Comparisons
The present fish shows some similarities to Mystus
montanus reported firstly by Jerdon (1849) from
Manantavady River in Wayanad and redescribed later
by Day (1865, 1877 & 1889) from the same locality;
similar to the present species, in M. montanus (Fig. 6.
C & 7. C; Table 3 & 4) occipital process reaches the
basal bone of dorsal fin. But the present fish greatly
differs from M. montanus in many other taxonomic
aspects. In M. montanus median longitudinal groove is
single (vs. median longitudinal groove on head appear
as two fontanels in the new fish), dorsal surface of head
smooth (vs. dorsal surface of head rough), maxillary
barbels extend up to half way between ventral and anal
fins (vs. maxillary barbels reaching posterior end of anal
fin base), external mandibulars reach behind half length
of pectoral fin (vs. external mandibulars extend
considerably behind half way between pectoral and
pelvic), dorsal spine with 8 teeth (vs. 6-7), adipose dorsal
originates from above the middle of origin of ventral and
anal fins (vs. adipose dorsal originates above middle of
ventral fin), highest point of adipose dorsal is roughly on
the level of dorsal profile of body (vs. adipose dorsal
projects fairly above the dorsal surface of body), pectoral
fin with 6 branched rays (vs. 6- 8), caudal fin with 15
rays (vs. 15- 17), pre dorsal length greater (39.1- 43.8
% SL vs. 30.8- 36.5), an oval or roughly rectangular
distinct deep black spot present on caudal base (vs. no
distinct black spot present on caudal base), a silvery line
along the side and two light yellow bands one above and
one below the lateral line (vs. a bluish black line along
the lateral line and light bands absent above or below
lateral line) and anal origin an eye diameter behind
adipose dorsal fin origin (vs. anal origin, a snout length
behind adipose dorsal origin).
Mystus oculatus (Fig. 6. E & 7. E; Tabel 3 & 4),
described by Valenciennes (1839) from Malabar, is a
related species of the new species; but some scientists
such as Steven Grant (1999, 2004) are of opinion that
M. oculatus is a synonym of M. armatus. Mystus
oculatus is similar to M. armatus in having a black spot
on the front of dorsal spine, median longitudinal groove
formed of two fontanels and occipital process reaches
the basal bone of dorsal fin. But Mystus oculatus shows
many taxonomical differences to M. armatus. In M.
oculatus, anal fin rays are iii, 9- 10 (vs. iii, 8 in M.
armatus), caudal fin with 17 rays (vs. 19), height of
Mystus indicus and M. heoki, two new catfishes from Kerala, India

4. Biosystematica, 2013, 7(1)
46
adipose dorsal fin is greater (5.5- 6.7 % SL vs. 4.7),
length of base of adipose dorsal fin shorter (17.2- 19.0
% SL vs. 28.9), inter dorsal distance greater (16.5- 18.2
% SL vs. 8.3), dorsal spine longer (14.4- 16.5 vs. 11.8),
median fontanel starts from in front of nasals and it reach
occipital process (vs. median fontanel starts from behind
nasal barbels origin and it never reach occipital process),
nasal barbels reach half way between posterior margin
of orbit and occiput (vs. reach occipital process),
maxillary barbels reach posterior most base of anal fin
(vs. reach to caudal base), posterior tip of adipose dorsal
fin never reaches the tip of anal fin (vs. reach behind
anal fin tip ), posterior base of adipose dorsal is in the
level of posterior base of anal fin (vs. considerably behind
the posterior base of anal fin), ventral fin tip never reach
anal fin origin (vs. reach anal fin origin), tip of pectoral
fin never reach anterior base of adipose dorsal (vs. reach
fairly behind the adipose dorsal origin) and no spine let
present before dorsal fin ( vs. a spine let present before
dorsal spine).
The new species differs greatly from Mystus
oculatus. In M. oculatus median longitudinal groove
on head fairly reach occiput (vs. it never reach occiput
in M. indicus), nasal barbels never reach occiput (vs.
reach occiput), tip of rayed dorsal never reach adipose
dorsal origin (vs. fairly reach adipose dorsal origin),
posterior base of adipose dorsal never reach above the
level of posterior base of anal fin (vs. fairly reach), 8- 9
branched rays present in pectoral fin (vs. 6- 8), 9- 10
branched rays present in anal fin (vs. 7- 8), 12- 14 teeth
present on inner side of pectoral spine (vs. 15- 16), a
distinct black spot present in front of dorsal spine base
(vs. no black spot), dorsal spine longer (14.4-16.5 % SL
vs. 8.8- 14.0), adipose dorsal fin base shorter (17.2- 19.0
% SL vs. 22.9- 33.7), inter dorsal distance greater (16.5-
18.2 % SL vs. 5.5- 9.4) and eye diameter greater (33.0-
40.0 % HL vs. 21.7- 29.2)
The present fish shows distinct differences from
Mystus armatus (Fig. 6. D & 7. D; Table 3 & 4)
described by Day (1865) from Karavannor River of
Kerala. In Mystus armatus, a spine let present in front
of dorsal spine (vs. spine let absent in the new species),
pectoral fin with 9 branched rays (vs. 6- 8), longer anal
fin (length of anal 18.2 % SL vs. 9.3- 15.4), adipose
dorsal fin shorter (4.7 % SL vs. 5.2- 6.5), caudal fin
with 19 rays (vs. 15- 17), median longitudinal groove on
head narrow and moderately deep (vs. shallow and wide),
maxillary barbels reach to caudal fin base (vs. maxillary
barbels reach only to posterior end of anal fin base), a
black spot present in front of dorsal spine (vs. black
spot absent), tip of ventral fin reaches anal fin origin
(vs. never reaches anal origin) and dorsal fin as high as
body below it (vs. dorsal fin fairly shorter than body
height at dorsal origin).
Mystus indicus can be distinctly separated from
Mystus malabaricus (Fig. 6. A & 7. A; Table 3 & 4)
described by Jerdon (1849) from ‘mountain streams of
Malabar’ and redescribed later by Day from Wayanad
(Day, 1865, 1877, 1889). It is a common Mystus species
of northern Kerala especially rivers of Wayanad (Hora
& Law, 1941; Hora, 1942; Jayaram, 1954, 1966, 1977
& Rajan, 1955). But no type specimens are available
for M. malabaricus. First author of this paper collected
some specimens of M. malabaricus from Mananthvady
River of Wayanad, from where Day collected and
redescribed it. As many new fishes of Jerdon were
described fromWayanad especially from Mananthavady
River, M. malabaricus might also have been described
from there. The presently collected specimens of
Mystus malabaricus from Mananthavady River were
found to be similar in characters with Jerdon’s
description. But Jerdon had not mentioned about a color
band in the mid lateral line of the body. But this character
can be seen only in larger specimens; smaller specimens
of M. malabaricus are without any distinct bands or
spots. That may be the reason why Jerdon not mentioned
about the mid lateral body stripe.
In Mystus malabaricus cephalic fontanel is single
(vs. two cephalic fontanels in the new species), occipital
process never reach basal bone of dorsal fin (vs. reaches
basal bone of dorsal fin), pectoral spine with 7- 13 teeth
(vs. 15- 16), head width equaling its length behind angle
of mouth (vs. width of head greater than its length behind
the angle of mouth), depth of caudal peduncle greater
(13.3- 15.5 % SL vs. 10.0- 12.3), width of caudal
peduncle shorter (3.0- 4.7 % SL vs. 5.0- 7.2), inter orbital
width lesser (26.8- 30.0 % HL vs. 31.0- 45.0) and width
of gape of mouth greater (40.0- 44.4 % HL vs. 31.0-
40.0).
The present species can be distinctly separated
from Mystus canarensis (= Hara malabarica) (Fig.
6. B & 7. B; Table 3 & 4) in many characters. ‘Hara
malabarica’ was described originally by Day (1865)
from Mundakkayam of Travancore Hills in Kerala.
Mystus canarensis was a replacement name suggested
for Hara malabarica by Steven Grant (1999, 2004). It
was based on a specimen from Canara (AMS B.7624)
and Grant considers it was from Mangalore of
Karnataka. But Day (1865) described Hara
malabarica from ‘Travancore’- “I received some
specimens of this fish from Rev. H. Baker (junior) from
PLAMOOTTIL &ABRAHAM

5. Biosystematica, 2013, 7(1)
47
the mountain streams of Travancore”. Day (1865, 1877
and 1889) described many other new species of fishes
(Haludaria fasciatus (=Puntius melanympyx Day),
Garra malabarica, Mesonemacheilus triangularis,
Puntius denisonii) all which were ‘received from Rev.
H. baker, jun…obtained in the stream at Mundakkayam,
in the hill ranges of Travancore’ (Day, 1865). Hara
malabarica also might have been received from
Mundakkayam of Kottayam district. More over the five
specimens collected by the first author of this paper from
Mundakkayam match in all taxonomical characters to
Day’ s description (1865) of Hara malabarica. Similar
to Day’s description (1865) the color of the presently
collected specimens is deep leaden, a dark brown spot
on shoulder surrounded by a lighter margin, bases of
pectoral and anal yellowish, no distinct colour band on
lateral line, occipital process never reaches basal bone
of dorsal fin, lateral line with sensory organs in the form
of short parallel tubes, pectoral fin with 8 teeth on inner
margin and outer margin finely serrated externally and
caudal fin lunated. As the Mystus canarensis of Grant
(1999) does not possess many of the above mentioned
characters and also because it was not collected from
its type locality in Kerala, the neotype designation cannot
be accepted here and the replacement name is
considered as invalid. (Wayanad, the locality of Rahul
kumar’s (photo of) Mystus canarensis is 245 miles away
and Mangalore, the type locality of Grant’s species (AMS
B.7624) is 314 miles away from Mundakkayam, the type
locality of Hara malabarica). The fresh specimens of
’Mystus canarensis’ from Wayanad by Rahul Kumar
given in Grant’s paper (1999, 2004) are undoubtfuly of
young ones of Mystus malabaricus. The first author
collected many specimens (ZSI FF 4931) of the latter
species from Mananthavady of Wayanad; young ones
of it are very similar to the photos of fresh specimens
given by Grant and they have no distinct mid lateral colour
band similar to ‘Hara malabarica’. The name Mystus
canarensis is used here tentatively as more studies are
required to propose a new name.
The Mystus indicus differs from Mystus
canarensis in having an occipital process which reaches
basal bone of dorsal fin (vs. occipital process never reach
basal bone of dorsal fin in Mystus canarensis), tip of
rayed dorsal fin reaches origin of adipose dorsal fin (vs.
never reach), maxillary and mandibular barbels with usual
thickness (vs. maxillaries and mandibulars with unusual
thickness), maxillaries reach to posterior end of anal fin
base (vs. maxillaries extend only to ventral tip or a little
behind it), caudal fin with 15- 17 rays (vs. caudal fin
with 18 rays), pectoral spine with 15- 16 teeth (vs. 8)
and dorsal spine with 6-7 teeth (vs. without teeth), head
depth greater (14.4- 16.2 % SLvs. 11.2- 13.0), pre dorsal
length shorter (30.8- 36.0 % SL vs. 36.2- 38.1), adipose
dorsal fin longer (5.2- 6.5 % SL vs. 3.8- 4.9), distance
from dorsal front to occiput shorter (60.6- 64.2 % HL
vs. 72.1- 79.6) and head length excluding snout longer
(72.0- 75.7 % HL vs. 65.3- 70.7).
Remarks: Mystus indicus is an edible fish present in
the lower reaches of Manimala River in Kerala. Local
fishermen have observed these bagrid fishes appear along
with other catfishes and Puntius species during monsoon
season. It is expected that more details of its biological
and taxonomical aspects may be unveiled in future by
collection and analysis of more specimens of these fishes.
Mystus heoki, sp. nov
(Fig. 3- 5; 6. F & 7. F; Table 2, 3 & 4)
urn:lsid:zoobank.org:act:FC8365F6-B11D-4C4E-A7CC-
A6B8334CF2F3
Holotype: ZSI/FF 4626, 137 mm SL, Elankadu,
Manimala River, Kerala, India; collected by Mathews
Plamoottil, 10 January 2011.
Paratypes: ZSI/WGRC 2419, 5 specimens, 85.5- 120
mm standard length, Elankadu, Manimala River, Kerala,
India; collected by Mathews Plamoottil, 10 January 2011.
Diagnosis: The new species can be differentiated from
all its congeners in having a markedly elongated body
(body height 15.0- 16.9 % SL), shorter head (18.9- 22.5%
SL), smaller eyes (16.7- 20.4 % HL), shorter rayed
dorsal (14.3- 15.4 % SL) and shorter pectoral fin (13.3-
14.3 % SL). Mystus heoki can be differentiated from
Mystus malabaricus in having seven branched rays in
pectoral fin (vs. eight in M. malabaricus), shorter head
(18.9- 22.5 % SL vs. 23.8- 24.7), and greater inter dorsal
distance (12.9- 15.3 % SL vs. 8.2- 11.3). The new
species differs from Mystus canarensis in having a
longer snout (36.4- 41.7 % HL vs. 31.7- 36.3 in the new
species), 7 branched rays in pectoral fin (vs. 8) and a
distinct blue band present on mid lateral line (vs. absent).
The new species differs from Mystus armatus, M.
montanus and M. oculatus in having short occipital
process which never reach basal bone of dorsal fin (vs.
comparatively long occipital process which reaches basal
bone of dorsal fin), dorsal spine without distinct teeth
(vs. 6-8 teeth), shorter head and shorter pectoral spine.
Description: Body elongate and compressed; body
depth at dorsal fin origin 7.3- 7.9 in total length and 5.9-
6.7 in standard length; Head depressed, head length
5.5- 6.5 in total length and 4.5- 5.3 in standard length;
Mystus indicus and M. heoki, two new catfishes from Kerala, India

6. Biosystematica, 2013, 7(1)
48
dorsal profile roughly straight from caudal base to dorsal
front and then bends moderately to snout tip. Ventral
profile nearly straight. Snout broad and its length 1.0-
1.3 times inter orbital distance; mouth sub terminal,
transverse, width of its gape 41.7- 48.7 in percent of
head length, upper jaw longer. Eyes comparatively
smaller, 4.1- 6.0 in head length, 1.9- 2.6 in inter orbital
width and 1.9- 2.2 in snout length; median longitudinal
groove on head reaches considerably behind posterior
border of orbit, but never reach occipital process; the
latter is short and does not reach the basal bone of dorsal
fin. Occipital process invisible as a thick layer of flesh
covers the region between its origin and dorsal fin front.
Teeth villiform and in bands on jaws and palate, a slightly
curved continuous band on upper jaw and a mesially
interrupted band on lower jaw.
Four pairs of barbels: one pair maxillaries reaching
considerably behind pelvic fin, mostly reach near to
the origin of anal fin, one pair nasals extending fairly
behind orbit, mostly reach very near to occiput, one
pair inner mandibulars reaching base of pectoral spine
and a pair of outer mandibulars reaching nearly end of
pectoral fin.
Rayed dorsal fin shorter, 1.2- 1.5 in head and 0.9-
1.1 in body depth at dorsal fin, originates near to the
posterior tip of pectoral, fairly in front of pelvic fin base,
nearer to adipose dorsal origin than to snout tip; rayed
dorsal fin provided with a slender spine, 1.7- 2.5 in head,
shorter than pectoral spine, its tip non- osseous,
filamentous and finely serrated behind, outer surface
smooth. Length of base of rayed dorsal fin 0.9- 1.1 in
inter dorsal distance, and 1.4- 1.8 in adipose dorsal base;
a fleshy ridge present at the base of first dorsal fin; outer
margin of the fin fairly convex. Adipose dorsal base
1.4- 1.6 times length of base of rayed dorsal fin, 1.6- 1.8
times anal fin base and 1.4- 1.7 in inter dorsal distance
and extending considerably behind the base of last anal
ray; posterior tip of adipose dorsal extends to tip of anal.
A moderate mid dorsal ridge present between rayed
dorsal and adipose dorsal. Pectoral fin short, 1.4- 1.6 in
head, its spine strong, 1.6-2.0 in head, with 10- 11 teeth
on inner edge but smooth externally, its tip non- osseous
and never reach pelvic fin; outer margin of pectoral
nearly straight. Pelvic fin, 1.6- 1.8 in head, origin just
behind last dorsal ray, nearer to anal origin than to pectoral
base. Pelvic fins shorter than pectoral fins and does not
reach anal fins; its outer margin convex. Anal fin, 1.9-
2.3 in head, origin just behind adipose dorsal origin,
nearer to pelvic origin than to caudal base and not reach
caudal fins; posterior margin of anal fairly straight.
Caudal fin bilobed, upper lobe longer 1.1- 1.2 times the
lower lobe, depth of caudal peduncle 1.4- 1.7 in its length
and 8.5- 9.1 in standard length; outer margin of caudal
lobes rounded.
Skin smooth; dorsal surface of head almost smooth
but with a number of minute pores. Sensory organs
clearly visible on lateral line.
Coloration: Fresh specimens: greenish above lateral line,
below it greenish white; fins hyaline to light greenish. A
bluish oval spot present on shoulder, another triangular
bluish spot on caudal base and a distinct and thick band
of bluish color in between the two along the lateral line,
width of which is more than half the diameter of eyes.
Body and fins decorated with tiny black dots.
Preserved specimens: after long preservation in formalin
body color turns to light brownish.
Distribution. - Currently known only from the type
locality in Kerala.
Habitat.- Manimala River at Elankadu, the type locality
of Mystus hoeki, is floored generally by rocky
substratum; patches of cobbles, boulders and gravelly
sand occur at certain places. The width of the river
channel varies between 20 m and 42 m. This high level
area is characterized by intermittent occurrence of
moderately dense riparian vegetation. Ficus
exasperata, F. glomerata, Gmelina arborea, Bambusa
bambos and B. vulgaris are the major trees. Wood trees
such as Teaks and Albizia, herbaceous plants such as
Maranta arundinacea, Colocasia esculenta and
Eclipta prostrata are infrequently seen. Anquilla
bengalensis, Danio malabaricus, Barilius bakeri,
Rasbora daniconius, Etroplus maculatus, Garra
mullya, Dawkinsia filamentosa, Mesonemacheilus
triangularis, Clarias dussumeiri, Glyptothorax
elankadensis, Mastacembelus armatus,
Macrognathus guentheri, Haludaria fasciatus etc are
the co- occurring fish species.
Etymology. – The specific epithet “heoki” is named
after the eminent scientist Heok Hee Ng, Singapore,
who contributed much to the taxonomy of catfishes.
Comparisons: The present species shows some
similarities to Mystus malabaricus, M. canarensis, M.
armatus, M. oculatus and M. montanus found in
Kerala. But these Bagrids can be distinctly distinguished
from the present fish in many taxonomic characters (Fig.
5 & 6; Table 1 & 2). In Mystus malabaricus (Jerdon)
8 branched rays present in dorsal fin (vs. 7 in Mystus
heoki), head is longer (head length 23.8- 24.7 % SL vs.
18.9- 22.5), body at dorsal fin origin higher (BDD 19.0-
20.5 % SL vs. 15.0- 16.9), pre dorsal distance greater
(34.8- 37.1 % SL vs. 31.7- 34.2), rayed dorsal fin longer
PLAMOOTTIL &ABRAHAM

7. Biosystematica, 2013, 7(1)
49
(17.6- 19.8 % SL vs. 14.3- 15.4), tip of rayed dorsal fin
reaches adipose dorsal front (vs. never reach adipose
dorsal), adipose dorsal base length greater (27.3- 30.7
% SL vs. 20.0- 23.9), anal fin longer (11.2- 15.1 % SL
vs. 9.2- 10.5), inter dorsal distance shorter (8.2- 11.3 %
SL vs. 12.9- 15.3), orbits set closely (inter orbital distance
26.8- 30.0 % HL vs. 32.4- 38.6), maxillaries reach only
to tip of pelvic fin (vs. reach origin of anal fin), nasal
barbels reach the midpoint between orbit and occiput
(vs. reach very near to occiput) and snout shorter (29.3-
34.7 % HL vs. 36.4- 41.7). Moreover, numerous tiny
pores are present on the head of the new fish which are
absent in M. malabaricus.
The present species can be distinctly separated
from Mystus canarensis in many characters. In Mystus
canarensis median longitudinal groove on head is divided
into two portions (vs. cephalic fontanel is single in Mystus
heoki), maxillaries reach to end of ventral fins (vs. reach
near to anal origin), outer mandibulars reach near to
middleofpectoralfins(vs.reachtipofpectorals),occipital
process covered by a thin sheath of flesh (vs. occipital
process covered by a thick layer of flesh), head longer
(HL 22.8- 24.3 % SL vs. 18.9- 22.5), body at dorsal fin
origin higher (17.2- 20.8 % SL vs. 15.0- 16.9), a dark
brown humeral spot surrounded by a lighter margin (vs.
absent), pre dorsal length greater (36.2- 38.1 % SL vs.
31.7- 34.2), rayed dorsal fin longer (15.8- 17.8 % SL vs.
14.3- 15.4), dorsal spine shorter (8.1- 9.4 % SL vs. 9.6-
12.8), 8-9 branched rays in pectoral fin (vs. 7), 18 rays
in caudal fin (vs. 15), both lobes of caudal fin overlap
each other (vs. caudal lobes never overlap), body deep
leaden (vs. greenish) and snout shorter (31.7- 36.3 %
HL vs. 36.4- 41.7).
Mystus oculatus, Mystus armatus and M.
montanus are not much related to the new species
because in them, unlike M. heoki, occipital process
reaches basal bone of dorsal fin. Mystus armatus (Day)
can be distinctly differentiated from the new species.
In Mystus armatus, head longer (26.0 % SL vs. 18.9-
22.5 in M. heoki), body deep (body height at rayed dorsal
fin 22.4 % SL vs. 15.0- 16.9), median longitudinal groove
on head divided into two fontanels (vs. single fontanel),
occipital process reaches the basal bone of dorsal fin
(vs. never reach), occipital process naked (vs. covered
by a thick layer of flesh), maxillaries reach near to caudal
fin base (vs. reach near to anal fin origin), outer
mandibulars reach near to ventral fin origin (vs. reach
near to tip of pectorals), rayed dorsal fin longer (22.4 %
SL vs. 14.3- 15.4), tip of first dorsal reach considerably
behind the origin of adipose dorsal (vs. never reach
adipose dorsal), length of base of adipose dorsal greater
(28.9 % SL vs. 20.0- 23.9), inter dorsal distance equals
to snout length (vs. fairly greater than snout length), tips
of caudal lobes pointed (vs. rounded), a black spot present
on the base of dorsal spine front (vs. no color spot) and
caudal fin with 19 rays (vs. 15).
Mystus oculatus (Valenciennes) can be distinctly
differentiated from the new species. In M. oculatus,
pectoral fin with 8-9 branched rays (vs. 7 in Mystus
heoki), anal fin with 9-10 branched rays (vs. 8), caudal
fin with 17 branched rays (vs. 15), median longitudinal
groove on head divided into two fontanels (vs. a single
fontanel), occipital process reaches basal bone of dorsal
fin (vs. never reach), eye diameter nearly equal to inter
orbital width (vs. fairly shorter than inter orbital width),
a deep black spot present in front of dorsal spine (vs.
absent), head longer (HL 23.3- 25.6 % SL vs. 18.9- 22.5),
head depth greater (66.0- 71.0 % HL vs. 52.0- 62.5),
inter dorsal distance greater (16.5- 18.2 % SL vs. 12.9-
15.3) and adipose dorsal fin base shorter (17.2- 19.0 %
SL vs. 20.0- 23.9).
Mystus montanus (Jerdon) is not a closely related
species to Mystus heoki. In M. montanus, occipital
process reaches the basal bone of dorsal fin (vs. occipital
process never reach the basal bone of dorsal fin in the
new species), tip of rayed dorsal fin reaches origin of
adipose dorsal (vs. never reach), posterior tip of outer
margin of dorsal spine with three small teeth (vs. outer
margin of dorsal spine smooth), a deep black rectangular
or oval spot present on caudal base (vs. a triangular
bluish spot), no distinct color band on mid lateral line
(vs. a thick blue band) and two thin yellowish lines
present one above and one below lateral line (vs. no
distinct color lines above or below lateral line).
Mystus heoki can be distinctly separated from M.
indicus in many relevant taxonomic characters. In
Mystus heoki body depth is lesser (15.0- 16.9 % SL vs.
18.8- 25.3 in Mystus indicus), head shorter (18.9- 22.5
% SL vs. 22.4- 26.0), head depth lesser (10.9- 12.5 %
SL vs. 14.4- 16.2), eyes smaller (16.7- 20.4 % HL vs.
24.0- 29.2), frontal groove single (vs. double), occipital
process shorter, never reaches basal bone of dorsal fin
(vs. longer, reaches basal bone of dorsal fin), rayed dorsal
fin shorter (14.3- 15.4 % SL vs. 15.8- 21.8) and pectoral
spine shorter, 10.5- 13.3 % SL (vs. 13.5- 17.6), 10- 11
teeth on pectoral spine (vs. 15- 16). M. heoki differs
from M. indicus in many other morphometric characters
as shown in Table 4.
Comparative material
Mystus malabaricus: ZSI FF 4931, 5 ex., 71.5-102 mm
SL, Kallodi, Mananthavady River,Wayanad, Kerala, coll.
Mystus indicus and M. heoki, two new catfishes from Kerala, India

8. Biosystematica, 2013, 7(1)
50
Table 1. Morphometric features of Mystus indicus (n=8)
Sl. No. Characters Holotype(HT) Range(HT+7Paratypes) Mean SD
1 Total length (mm) 131.0 102.5-136.0 120.4 10.8
2 Standard length(mm) 100.0 81.0-107.0 94.1 8.0
Percentage of standard length
3 Head length 24.0 22.4-26.0 24.8 2.2
4 Head depth 15.0 14.4-16.2 15.3 0.6
5 Head width 18.0 16.7-20.2 18.2 1.0
6 Body depth at dorsal origin 21.0 18.8-25.3 20.5 3.0
7 Body depth at anal origin 19.0 17.8-21.2 18.8 1.9
8 Body width at dorsal origin 17.8 16.7-19.2 17.2 1.2
9 Body width at anal origin 13.0 9.4-13.0 11.5 1.1
10 Pre dorsal length 36.0 30.8-36.0 34.3 2.0
11 Post dorsal length 70.0 64.5-70.8 66.3 3.4
12 Pre pectoral length 22.0 20.0-22.9 21.6 1.0
13 Pre pelvic length 51.0 50.6-55.5 53.8 1.6
14 Pre anal length 70.0 69.2-76.8 73.8 2.7
15 Length of rayed dorsal fin 17.5 15.8-21.8 18.6 2.1
16 Height of adipose dorsal fin 5.5 5.2-6.5 5.8 0.6
17 Length of pectoral 19.0 17.3-19.2 18.1 1.3
18 Length of pelvic 17.0 12.1-17.6 14.7 2.1
19 Length of anal 13 9.3-15.4 11.5 1.9
20 Length of dorsal spine 11.2 10.2-14.0 12.0 1.7
21 Length of pectoral spine 17.0 13.5-17.6 15.3 1.7
22 Length of base of RD 16.0 15.6-17.8 16.6 1.3
23 Length of base of AD 28.0 26.2-33.7 29.3 3.1
24 Length of base of pectoral 5.2 4.6-5.8 5.2 0.7
25 Length of base of pelvic 3.2 3.2-4.3 3.7 0.4
26 Length of base of anal 15.0 11.2-15.0 13.3 2.1
27 Length of base of caudal 13.0 12.9-14.0 13.3 0.9
28 Distance from pectoral to pelvic 30.0 29.2-33.3 31.2 1.6
29 Distance from pelvic to anal 24.0 20.6-24.0 22.4 1.4
30 Distance from anal to caudal 29.8 29.2-30.6 29.8 1.6
PLAMOOTTIL &ABRAHAM
Mathews Plamoottil, 20.03.2013; ZSI/SRC 313, 2 ex.,
Muthanga,coll.R.S.Pillai,12.10.1976;ZSI/WGRC9395,
1 ex., Ranipuram, Kazargod Dt, coll. M. madhavan,
idenfified by K.C. Gopi, 07.07.1996; ZSI unreg. 7 ex.,
Mananthavady River at Choothakadavu near Kaniyaram,
coll. K. C. Jayaram, 14.02.1985; ZSI uncat, 3 ex., Cauvery
River, Kerala, coll. G. M. Natarajan, 1984; Mystus
oculatus: ZSI FF 4933, 5 ex., 85- 91 mm SL,Arattupuzha,
Karavannoor River, Trichur, Kerala, coll. Mathews
Plamoottil, 10.01.2013; ZSI 487, I ex., India, purchased
from Francis Day; ZSI, unreg, 4 ex., 78.0- 86.8 mm SL,
Chaliyar River at Edavanna, 2 km from Manjeri, Kerala,
coll. K. C. Jayaram and Anuradha, 18.02. 1985; Mystus
armatus: STC/DOZ 10, 1 ex., 84.8 mm SL,Arattupuzha,
Karavannoor River, Trichur, coll. Mathews Plamoottil,
13.01. 2013; ZSI/WGRC 7886, 2 ex., Kuniyanpuzha,
Kazargod, coll. Jafer Sherif, identified by K. C. Gopi,
01.07.1995; ZSI/WGRC 7425, 1 ex., Bhavani River,
Wayanadu, coll. P. M. Suresh, 02.02. 1995; ZSI/WGRC/
8470, 3 ex., Thoonacadavu dam, Parambikkulam WLS,
Palakkadu, coll. P. M. Sureshan, identified by. K. C. Gopi,
27.10.95; ZSI uncat. 10 ex., 60- 84 mm SL, Puzhakkal,
15 km north of Trichur, Kerala, coll. K. C. Jayaram and
Anuradha Sanyal, 20. 02. 1985; ZSI uncat. 6 ex., 56- 77
mm SL, Muppinipotti on Punnanpuzha, Kerala, coll. K.
C. Jayaram & Anuradha Sanyal, 18.02. 1985; ZSI/
WGRC/9397, 1 ex., Ranipuram, Kazargod, coll. M.
Madhavan, idenfified by K.C. Gopi, 07.07.1996; Mystus
montanus: STC/DOZ 11, 1 ex., 67.5 mm SL, Koodal
kadavu, Mananthavady River, Wayanad, coll. Mathews
Plamoottil, 16.03.2013; KFRI/88, 1 ex., Noolpuzha, coll.
Shaji, C. P, 11.06.1996; ZSI uncat, 8 ex., 65- 76 mm SL,

9. Biosystematica, 2013, 7(1)
51Mystus indicus and M. heoki, two new catfishes from Kerala, India
Sl. No. Characters Holotype(HT) Range(HT+7Paratypes) Mean SD
31 Distance from AD to caudal 12.3 11.5-13.7 12.5 0.9
32 Length of caudal peduncle 16.0 15.9-17.9 16.7 0.8
33 Depth of caudal peduncle 11.8 10.0-12.3 11.5 0.8
34 Width of caudal peduncle 7.2 6.0-7.2 6.6 0.9
35 Distance from RD toAD 8.0 7.2-9.4 8.0 1.2
36 Length of upper caudal lobe 32.0 26.2-32.0 28.4 1.8
37 Length of lower caudal lobe 28.0 20.6-28.0 24.7 2.3
38 Distance from anal to vent 4.7 3.9-4.9 4.5 0.7
39 Distance from ventral to vent 15.2 14.2-16.6 15.3 1.1
40 Head length (mm) 24.0 20.0-29.0 23.4 2.9
Percent of head length
41 Head depth 62.5 59.0-66.7 63.4 3.8
42 Head width 75.0 68.0-83.3 73.9 6.3
43 Distance from occiput to snout 86.0 85.4-86.2 85.8 3.7
44 Distance from occiput to dorsal 62.8 60.6-64.2 62.5 4.0
45 Length of frontal groove 62.8 56.6-66.5 62.0 3.9
46 Length of occipital process 56.6 43.6-56.8 48.4 2.8
47 Width of base of occipital process 9.6 8.3-12.0 10.3 1.0
48 Eye diameter 29.2 24.0-29.2 26.7 2.4
49 Postorbital length 45.9 40.4-46.8 44.4 1.8
50 Head length excluding snout 72.2 72.0-75.7 73.3 2.6
51 Inter orbital width 37.5 36.3-45.0 39.2 4.4
52 Inter narial width 21.7 20.0-25.0 23.2 2.2
53 Snout length 37.5 36.2-42.5 38.8 3.1
54 Width of gape of mouth 37.5 34.8-40.9 38.4 3.3
55 Length of maxillary barbels 295.8 289.7-375.0 328.1 29.9
56 Length of nasal barbels 56.3 44.8-80.0 61.1 10.9
57 Length of outer mandibular barbels 120.8 106.9-170.0 141.9 21.8
58 Length of inner mandibular barbels 87.5 75.8-105.0 94.8 9.8
Ratios
59 TL/head length 5.4 5.0-5.7 5.4 0.5
60 TL/body height at dorsal fin origin 6.2 5.0-6.8 5.6 1.1
61 SL/ head length 4.2 3.8-4.5 4.1 0.4
62 SL/ body depth at dorsal fin origin 4.6 4.0-5.3 4.8 0.5
63 SL/ height of adipose dorsal fin 5.6 5.2-6.5 5.8 1.1
64 HL/height of rayed dorsal fin 1.3 1.1-1.7 1.3 0.3
65 HL/length of dorsal spine 1.7 1.6-2.2 2.0 0.3
66 HL/length of pectoral fin 1.3 1.3-1.6 1.4 0.3
67 HL/length of pectoral spine 1.6 1.4-1.7 1.6 1.0
68 HL/length of pelvic fin 1.5 1.4-1.8 1.6 0.6
69 HL/length of anal fin 2.2 1.6-2.4 2.0 1.0
70 HL/eye diameter 4.0 3.6-4.2 3.8 0.4
71 Length of base ofAD/ LBRD 1.8 1.6-2.5 1.9 0.3
72 Length of base of AD/LBA 2.0 1.9-3.1 2.1 0.3
73 Length of caudal peduncle/DCP 1.5 1.3-1.7 1.4 0.3
74 Inter orbital width/Eye diameter 1.3 1.3-1.7 1.4 0.2
75 Snout length/eye diameter 1.5 1.3-1.7 1.4 0.3

10. Biosystematica, 2013, 7(1)
52
Table 2. Morphometric features of Mystus heoki new sp. (n=6)
No Characters Holotype(HT) Range(HT+5PT) Mean SD
1 Total length (mm) 167.0 105.5-167.0 134.8 18.5
2 Standard length (mm) 137.0 85.5-137.0 108.0 15.8
Percentage of standard length
3 Head length 18.9 18.9-22.5 21.1 1.1
4 Head depth 10.9 10.9-12.5 12.1 0.7
5 Head width 15.3 14.8-17.4 16.1 0.9
6 Body depth at dorsal origin 16.8 15.0-16.9 16.2 1.2
7 Body depth at anal origin 15.3 13.3-16.4 15.2 0.9
8 Body width at dorsal origin 16.1 12.5-15.2 15.4 1.7
9 Pre dorsal length 32.8 31.7-34.2 33.7 1.5
10 Post dorsal length 67.2 59.7-67.2 64.9 2.3
11 Pre pectoral length 14.6 14.6-19.2 18.6 1.5
12 Pre pelvic length 45.9 43.3-45.9 45.2 1.2
13 Pre anal length 66.1 60.9-66.1 64.9 2.3
14 Length of rayed dorsal 15.3 14.3-15.4 16.3 1.3
15 Length of adipose dorsal 3.6 3.6-5.7 4.2 0.7
16 Length of pectoral 13.9 13.3-14.3 13.9 0.6
17 Length of pelvic 11.7 11.7-13.1 12.4 0.6
18 Length of anal 10.0 9.2-10.5 10.9 1.2
19 Length of caudal fin 23.7 22.7-24.5 23.6 24.0
20 Length of dorsal spine 10.2 9.6-12.8 10.6 1.4
21 Length of pectoral spine 12.0 10.5-13.3 12.6 1.5
22 Length of base of rayed dorsal 14.6 14.0-14.8 14.6 0.4
23 Length of base of adipose dorsal fin 23.3 20.0-23.9 22.4 2.9
24 Length of base of anal fin 12.4 11.7-13.5 13.0 0.9
25 Length of base of caudal fin 14.8 14.8-15.2 15.0 0.6
26 Distance from pectoral to pelvic 28.1 21.0-28.1 24.3 2.6
27 Distance from pelvic to anal 19.4 17.3-19.4 18.5 0.9
28 Distance from anal to caudal 28.6 29.4-33.0 31.2 1.6
29 Distance from Adipose dorsal to caudal fin 15.6 14.1-16.8 15.8 1.4
30 Length of caudal peduncle 16.0 16.0-18.7 17.9 1.2
31 Depth of caudal peduncle 10.9 10.0-11.8 10.7 0.7
32 Width of caudal peduncle 5.1 5.1-5.9 5.6 0.7
33 Distance from rayed dorsal to adipose dorsal 13.9 12.9-15.3 13.6 1.1
34 Distance from ventral to vent 16.8 15.4-17.2 16.4 1.1
35 Distance from anal to vent 3.3 2.8-4.8 3.5 1.4
36 Head length (mm) 26.0 18.5-26.0 23.1 2.5
Percentage of head length
37 Eye diameter 19.2 16.7-20.4 19.9 3.5
38 Inter orbital width 38.5 32.4-38.6 35.9 2.3
39 Snout length 38.5 36.4-41.7 38.9 1.7
40 Width of gape of mouth 46.2 41.7-48.7 46.7 2.8
41 Distance from occiput to snout 85.0 83.7-85.2 84.4 4.2
42 Distance from occiput to dorsal fin 74.2 73.8-75.4 74.6 1.4
PLAMOOTTIL &ABRAHAM

11. Biosystematica, 2013, 7(1)
53
No Characters Holotype(HT) Range(HT+5PT) Mean SD
43 Head length excluding snout 67.1 66.8-67.7 67.2 0.7
44 Post orbital length 46.2 45.8-47.3 46.6 1.3
45 Length of frontal groove 63.7 62.7-63.9 63.2 2.1
46 Length of maxillary barbels 284.6 200.0-284.6 258.9 26.9
47 Length of nasal barbels 65.4 64.8-70.8 66.9 3.8
48 Length of outer mandibulars 130.8 92.0-137.5. 120.5 16.8
49 Length of inner mandibulars 76.9 72.0-83.3 77.2 5.1
Ratios
50 Total length/head length 5.7 5.5-6.5 5.8 0.7
51 TL/body height at dorsal fin origin 7.6 7.3-7.9 7.6 0.4
52 Standard length/head length 4.8 4.5-5.3 4.8 0.6
53 SL/body height at dorsal fin origin 6.2 5.9-6.7 6.2 0.7
54 Length of rayed dorsal fin/BDD 0.9 0.9-1.1 1.0 0.1
55 Head length/length of rayed dorsal fin 1.3 1.2- 1.5 1.3 0.1
56 Head length/length of dorsal spine 2.0 1.7-2.5 2.0 0.5
57 Head length/length of pectoral spine 1.8 1.6-2.0 1.8 0.2
58 Head length/length of pelvic 1.6 1.6-1.8 1.7 0.1
59 Head length/ length of anal fin 2.0 1.9-2.3 2.1 0.4
60 Length of base of RD/inter dorsal distance 1.1 0.9-1.1 1.0 0.1
61 Length of base of AD/Length of base of RD 1.5 1.4-1.6 1.5 0.1
62 Length of base of adipose dorsal/LBA 1.6 1.6-1.8 1.7 0.2
63 LCP/depth of caudal peduncle 1.5 1.4-1.7 1.6 0.1
64 Length of lower CL/ length of upper CL 1.2 1.1-1.2 1.1 0.1
65 LBAD/inter dorsal distance 1.5 1.4-1.7 1.5 0.1
66 Head length/eye diameter 5.2 4.1-6.0 5.2 0.6
67 SL /depth of caudal peduncle 8.8 8.5-9.1 8.9 0.4
68 Inter orbital length/eye diameter 2.1 1.9-2.6 2.2 0.5
69 Snout length/eye diameter 2.0 1.9-2.2 2.0 0.4
70 Inter orbital width/ snout length 1.0 1.0-1.3 1.2 0.1
Mystus indicus and M. heoki, two new catfishes from Kerala, India
Table 3. Meristic counts of Mystus heoki, M. indicus and relative species
Characters Mystus heoki M. indicus M. montanus M. armatus M. malabaricus M. canarensis M. oculatus
Dorsal fin II,7 I,7 I,7 II,7 I, II, 6-7 I,7 I,7
Pectoral fin I,7 I,6-8 I,6 I,9 I,7-8 I,9 I,8-9
Ventral fin i,5 i,5 i,5 i,5 i,5 i,5 i,5
Anal fin ii-iii,8 iii,7-8 iii,8 iii,8 iii,8 iii,8 iii,9-10
Caudal fin 15 15-17 15 19 17 18 17
DspT 0 6-7 8 6 0 0 2-8
PspT 10-11 15-16 14-15 10-14 7-13 8 12-14

12. Biosystematica, 2013, 7(1)
54
Table 4. Biometric characters of relative species of Mystus heoki and M. indicus
Characters M. heoki M. indicus M. M. oculatus M.armatus M. M.
malabaricus ZSI 4933 STC/ montanus canarensis
ZSI 4931 DOZ 10 STC/DOZ 11 ZSI 4939
Total length (mm) 105.5-167.0 102.5-136.0 92.0-127.0 111.0-122.0 112.8 86.3 107.0-126.0
Standard length(mm) 85.5-137.0 81.0-107.0 71.5-102.0 85.0-91.0 84.8 67.5 87.0-101.0
Percentage of Standard length
Head length 18.9-22.5 22.4-26.0 23.8-24.7 23.3-25.6 26.0 28.1 22.8-24.3
Head depth 10.9-12.5 14.4-16.2 13.2-14.4 16.0-18.2 16.0 17.0 11.2-13.0
Head width 14.8-17.4 16.7-20.2 16.7-17.8 15.1-18.3 19.5 20.7 15.0-17.8
Body depth at dorsal origin 15.0-16.9 18.8-25.3 19.0-20.5 20.9-23.0 22.4 23.0 17.2-20.8
Body depth at anal origin 13.3-16.4 17.8-21.2 16.8-17.8 17.4-19.2 18.9 19.3 16.6-18.1
Body width at dorsal origin 12.5-15.2 16.7-19.2 15.2-16.8 15.5-16.7 17.7 17.0 14.7-16.8
Pre dorsal length 31.7-34.2 30.8-36.0 34.8-37.1 37.2-37.8 36.0 40.0 36.2-38.1
Post dorsal length 59.7-67.2 64.5-70.8 64.8-67.1 63.1-66.2 66.0 64.4 62.0-65.8
Pre pectoral length 14.6-19.2 20.0-22.9 20.4-22.3 22.0-26.1 23.6 23.7 18.7-21.3
Pre pelvic length 43.3-45.9 50.6-55.5 49.0-51.0 47.1-51.2 49.5 50.4 48.7-49.7
Pre anal length 60.9-66.1 69.2-76.8 67.1-69.4 68.1-75.6 67.8 72.6 66.3-70.7
Length of rayed dorsal fin 14.3-15.4 15.8-21.8 17.6-19.8 21.1-23.6 22.4 20.4 15.8-17.8
Height of adipose dorsal 3.6-5.7 5.2-6.5 4.1-5.7 5.5-6.7 4.7 6.0 3.8-4.9
Length of pectoral 13.3-14.3 17.3-19.2 15.7-17.8 18.0-20.0 20.0 17.8 16.6-17.2
Length of pelvic 11.7-13.1 12.1-17.6 13.7-15.3 13.9-15.6 18.3 13.3 14.0-16.1
Length of anal 9.2-10.5 9.3-15.4 11.2-15.1 13.0-15.1 18.2 15.6 11.3-13.6
Length of dorsal spine 9.2-10.5 10.2-14.0 9.8-10.8 14.4-16.5 11.8 10.4 8.1-9.4
Length of pectoral spine 10.5-13.3 13.5-17.6 12.0-13.3 15.1-17.2 15.3 16.2 11.2-13.0
Length of base of RD 14.0-14.8 15.6-17.8 15.3-16.2 14.0-15.3 17.1 16.3 13.0-15.0
Length of base of AD 20.0-23.9 26.2-33.7 27.3-30.7 17.2-19.0 28.9 21.5 22.8-25.1
Length of base of anal 11.7-13.5 11.2-15.0 13.6-15.3 12.8-14.0 12.8 11.1 9.8-12.4
Length of base of caudal 14.8-15.2 12.9-14.0 15.3-16.5 11.8-13.9 14.5 14.5 12.0-14.7
Inter dorsal distance 12.9-15.3 7.2-9.4 8.2-11.3 16.5-18.2 8.3 8.9 11.8-15.5
Distance from pectoral to pelvic 21.0-28.1 29.2-33.3 28.3-31.7 25.9-30.8 28.3 28.1 28.7-32.4
Distance from pelvic to anal 17.3-19.4 20.6-24.0 19.6-20.1 19.8-22.2 18.2 22.2 18.7-22.4
Distance from anal to caudal 29.4-33.0 29.2-30.6 30.0-3.6 28.3-314 30.7 28.1 30.2-31.6
Distance fromAD to caudal 14.1-16.8 11.5-13.7 12.0-14.2 16.1-18.0 14.2 14.7 11.8-14.9
Length of caudal peduncle 16.0-18.7 15.9-17.9 16.4-18.5 15.6-19.2 18.9 14.8 18.2-20.1
Depth of caudal peduncle 10.0-11.8 10.0-12.3 13.3-15.5 10.6-11.6 11.8 11.9 11.9-14.1
Width of caudal peduncle 5.1-5.9 6.0-7.2 3.0-4.7 4.7-6.1 3.5 5.6 4.0-5.4
Distance from anal to vent 2.8-4.8 3.9-4.9 3.6-5.1 6.0-7.6 5.1 4.4 4.8-5.4
Distance from ventral to vent 15.4-17.2 14.2-16.6 15.3-16.8 14.0-15.9 14.2 15.6 14.1-16.7
Head length (mm) 18.5-26.0 20.0-29.0 17.5-24.5 20.0-23.0 22.0 19.0 20.0—24.5
Percentage of head length
Head depth 52.0-62.5 59.0-66.7 53.7-60.0 66.0-71.3 61.4 60.5 48.8-56.1
Head width 70.3-83.3 68.0-83.3 68.3-72.2 65.0-71.7 75.0 73.7 65.1-74.1
Eye diameter 16.7-20.4 24.0-29.2 23.7-29.3 28.3-40.0 30.0 26.3 20.4-27.5
Inter orbital width 32.4-38.6 36.3-45.0 26.8-30.0 23.6-27.5 28.6 33.2 30.2-35.0
Inter narial width 20.2-24.3 20.0-25.0 18.4-22.2 16.0-17.5 22.7 18.4 18.6-25.0
Snout length 36.4-41.7 36.2-42.5 29.3-34.7 26.1-28.3 31.8 30.5 31.7-36.3
Length of frontal groove 62.7-63.9 56.6-66.5 55.6-68.3 77.8-89.5 43.2 46.8 40.8-56.1
Post orbital length 45.8-47.3 40.4-46.8 41.5-48.9 41.0-45.6 40.5 47.4 44.0-47.0
Head length excluding snout 66.8-67.7 72.0-75.7 67.8-70.5 70.5-74.8 68.2 73.7 65.3-70.7
Width of gape of mouth 41.7-48.7 34.8-40.9 40.0-44.4 35.0-41.3 40.0 44.7 39.0-40.8
Distance from occiput to snout 84.5-84.7 85.4-86.2 83.7-87.8 85.0-95.0 84.1 85.3 81.6-88.4
Distance from occiput to dorsal 73.8-75.4 60.6-64.2 61.1-65.8 58.3-66.5 54.5 52.6 70.7-79.6
Length of maxillary barbels 200.0-284.6 289.7-375.0 253.2-291.7 308.7-322 363.6 226.3 228.6-265.9
Length of nasal barbels 64.8-70.8 44.8-80.0 61.2-75.0 66.0-70.0 77.3 57.9 59.2-85.4
Length of outer mandibulars 92.0-137.5. 106.9-170.0 110.2-126.7 122.6-145 170.5 100.0 92.7-132.1
Length of inner mandibulars 72.0-83.3 75.8-105.0 78.8-88.6 72.7-90.0 100.0 63.2 65.3-75.0
PLAMOOTTIL &ABRAHAM

13. Biosystematica, 2013, 7(1)
55Mystus indicus and M. heoki, two new catfishes from Kerala, India
Fig. 1. Fresh specimen of Mystus indicus, Paratype, ZSI/WGRC/2418
Fig. 2. Formalin preserved specimen of M. indicus, Holotype, ZSI FF 4627
Fig. 3. Freshly collected specimen of M. heoki, Paratype, ZSI/WGRC 2419

14. Biosystematica, 2013, 7(1)
56
Fig. 4. Freshly collected specimen of M. heoki, Holotype, ZSI FF 4626
Fig. 5. Preserved specimen of M. heoki, Paratype, ZSI/WGRC 2419
PLAMOOTTIL &ABRAHAM

15. Biosystematica, 2013, 7(1)
57
Fig. 6. Relative species of M. indicus and M. heoki
A. Mystus malabaricus; B. M. canarensis; C. M. montanus; D. M. armatus; E. M. oculatus; F. M. heoki; G. M. indicus.
Fig. 7. Dorsal view of head of M. indicus, M. heoki and relative species
A. Mystus malabaricus; B. M. canarensis; C. M. montanus; D. M. armatus; E. M. oculatus; F. M. heoki; G. M. indicus.
Mystus indicus and M. heoki, two new catfishes from Kerala, India

16. Chittoorpuzha at Thathamangalam road bridge about 17
km south of Palaghat town, coll. K. C. Jayaram &
Anuradha Sanyal, 20. 02. 1985; ZSI uncat, 7 ex., 59- 78
mm SL, Malampuzha dam, Kerala, coll. K. C. Jayaram
& Anuradha Sanyal, 22.02. 1985; ZSI/SRC/5217, 1 ex.,
42 mm SL, Parambikulam, coll. M. B. Reghunathan,
13.08.97; Mystus canarensis: ZSI FF 4939, 1 ex., 88.5
mm SL, Manimala River at Mundakkayam, Kerala, coll.
Mathews Plamoottil, 10.02.12; STC/DOZ 12, 4 ex., 87-
101 mm SL, Manimala River at Mundakkayam, Kerala,
coll. Mathews Plamoottil, 10.02.12.
Acknowledgments
First author acknowledges the University Grants Commission
of India for sanctioning Faculty Development Programme to
undergo research. Both the authors acknowledge Principal,
St. Thomas College, Kozhencherry, Kerala for providing the
facilities.
References
Day, F. 1865. The Fishes of Malabar. Bernard Quaritch,
London, pp. 184.
Day, F. 1877. The fishes of India: being a natural history of
the fishes known to inhabit the seas and fresh waters
of India, Burma, and Ceylon. London, pp. 448- 452.
Day, F. 1889. Fauna of British India including Ceylon and
Burma. Taylor and Francis, London, pp. 159- 162.
Easa, P. S., & C. P. Shaji. 2003. Biodiversity documentation
for Kerala, Part 8: Freshwater fishes. Kerala Forest
Research Institute, Peechi, pp.71- 79.
Grant, S. 1999. A replacement name (nomen novum) and
neotype designation for Hara malabarica Day, 1865,
with notes on related species (Siluriformes). Aqua. J.
Ichthyol. & Aquatic Biol. 3 (4): 169- 174.
Grant, S. 2004. The striped cat fishes of the genus Mystus
Scopeli 1777 (Siluriformes: bagridae). J. Catfish Study
Group 5 (2): 5- 17.
Hora, S. L., & N. C. Law. 1941. Siluroid fishes of India, Burma
and Ceylon. IX. Rec. Indian Mus. 43 (1): 238.
Hora, S. L. 1942. Alist of the fishes of the Mysore state and
its neighboring hill ranges of the Nilgiris, Wayanad
and Coorg. Rec. Indian Mus. 44 (2): 197.
Jayaram,K.C.1954. SiluroidfishesofIndia,BurmaandCeylon.
XIV. Fishes of the genus Mystus Scopeli. Rec. Indian.
Mus. 51 (4): 544.
Jayaram, K. C. 1966. Contributions to the study of Bagrid
fishes (Siluroidea: Bagridae). 1.Asystematic account
of the genera Rita Bleeker, Rama Bleeker, Mystus
scopeli, and Horabagrus Jayaram. Int. Rev. Ges.
Hydrobiol. 51 (3): 446.
Jayaram, K. C. 1977. An aid to identification of siluroids. 1.
Bagridae. Rec. Zool. Surv. India. Occ. Paper No.8: 27.
Jayaram, K. C., & A. Sanyal. 2003. Revision of the fishes of
the genus Mystus Scopoli. Records of Zoological
Survey of India, Occasional Paper No. 207, pp. 1-136.
Jayaram, K. C. 2002.Fundamentals of fish taxonomy. Narendra
publishing House, Delhi, pp. 53-65.
Jayaram, K. C. 2006. Catfishes of India, Narendra Publishing
House, Delhi, pp. 34-58.
Jayaram, K. C. 2010. Fresh water fishes of the Indian region.
Narendra publishing House, Delhi, pp. 256-262.
Jerdon, T. C. 1849. On the fresh water fishes of Southern
India. Madras J. Lit. Sci.15:302-345.
Misra, K. S. 1976. The fauna of India and Adjacent countries.
Zoological Survey of India, Kolkata, pp. 81-101.
Rajan,S.1955.Notesonacollectionoffishfromtheheadwaters
of the Bhavani River, South India. J. Bombay nat. Hist.
soc. 53: 45.
Talwar, P. K., &A. Jhingran. 1991. Inland fishes of India and
adjacent countries. Oxford and IBH publishing Co.
Pvt. Ltd, pp. 554-573.
Valenciennes, M. A. 1839. Histoire Naturelle des Poossons.
Paris 14: 424.
PLAMOOTTIL &ABRAHAM
Received: 10 Oct 2012
Accepted: 10 May 2013
Published: 4 Nov 2013