First record of Mugil hospes in the Gulf of Mexico and its identification from Mugil curema using ctenii

Abstract

This study gives the first record of Mugil hospes distributed in the Gulf of Mexico. This species previously has been confused with its congener Mugil curema and can be easily differentiated by the shape of the ctenii on their scales.

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Journal of Fish Biology (2011) 78, 386–390
doi:10.1111/j.1095-8649.2010.02863.x, available online at wileyonlinelibrary.com
First record of Mugil hospes in the Gulf of Mexico and its
identification from Mugil curema using ctenii
A. L. Ib ´
a˜
nez*†,M.Gonz
´
alez-Castro‡and E. Pacheco-Almanzar*
*Universidad Aut´onoma Metropolitana-Iztapalapa Departamento de Hidrobiología, Av. San
Rafael Atlixco 186, Col. Vicentina, M´exico D.F. 09340, M ´exico and ‡Laboratorio de
Ictiologia, Departamento de Ciencias Marinas, UNMdP, Argentina
(Received 9 February 2010, Accepted 28 October 2010)
This study gives the first record of Mugil hospes distributed in the Gulf of Mexico. This species
previously has been confused with its congener Mugil curema and can be easily differentiated by
the shape of the ctenii on their scales. ©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles
Key words: ctenii shape; distribution; mullet; scales.
Agassiz (1834) classified fishes on the basis of four scale types: ‘Les Placoides’, ‘Les
Ganoides’, ‘Les Ctenoides’ and ‘Les Cycloides’ (Roberts, 1993). Later, Goodrich
(1907) and Lagler (1947) contributed further work on the importance of scales in
fish classification. More recently, scale morphology has been employed to identify
inland fishes of North America (Daniels, 1996) and also to make keys of freshwa-
ter fishes from various regions such as California (Casteel, 1972) and Britain and
Ireland (Maitland, 2004). Scales have been used for the identification of species of
Mugilidae from India, Israel and Taiwan (Pillay, 1951; Chervinski, 1984; Liu &
Shen, 1991). Besides the overall morphology of the scales, the shape of the ctenii
is also species specific and has been used to distinguish between juveniles of stiped
mullet Mugil cephalus L. and white mullet Mugil curema Valenciennes (Ib´
a˜
nez &
Gallardo-Cabello, 2005).
Distinguishing M. curema and hospe mullet Mugil hospes Jordan & Cuvier is
not always straightforward for researchers not experienced in fish identification. The
two species are genetically closely related (Fraga et al., 2007) and morphologically
similar, with almost the same numbers of scales in longitudinal series (35 – 40 in M.
curema v. 37–40 in M. hospes ) and in circumpeduncular series (17 –19 in M. curema
v. 19 in M. hospes) (Harrison, 2002; Harrison et al., 2007). According to Harrison
(2002) and Harrison et al. (2007), M. hospes has an elongate body (body depth at
origin of first dorsal fin is 22– 26% of standard length, LS; body depth at origin of
anal fin is usually 21– 23% LS); the pectoral fin has 13 or 14 soft rays [ ´
Alvarez-
Lajonchere (1982) reported 16 pectoral rays, although that is not confirmed in this
†Author to whom correspondence should be addressed. Tel.: +52 55 5804 6585; email: ana@xanum.uam.mx
386
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles

FIRST RECORD OF MUGIL HOSPES IN THE GULF OF MEXICO 387
study] and is long, reaching the level of the origin of the first dorsal fin or extending
just beyond this (pectoral-fin length is 21 – 24% LS, 80 –96% of head length, LH);
there are 11– 13 scales in longitudinal series anterior to the tip of pectoral fin; the
teeth on the lips are minute. In comparison, M. curema has a deeper body (body
depth at origin of first dorsal fin usually 26– 30% LS; body depth at origin of anal fin
usually 21– 27% LS); the pectoral fin has 15 – 17 soft rays, and usually does not quite
reach the level of the origin of the first dorsal fin (pectoral-fin length is 16– 21% LS,
70–83% LH); 8– 11 scales in longitudinal series anterior to tip of pectoral fin; the
teeth are small to minute. Moreover, Gonz´
ales-Sans´
on et al. (1978) mentioned that
in fresh specimens M. curema shows a black iris and the presence of a moderate-to-
large ‘goldish’ spot on the opercle, whereas M. hospes has a yellow iris and lacks
the ‘goldish’ spot.
Although the two species can be diagnosed by key differences in the number of
soft rays in the pectoral fin and numbers of scales in longitudinal series anterior to
the tip of the pectoral fin, the shape of the scales’ ctenii shows specific variations
that provide additional, reliable information for identification.
Between November 2008 and January 2009 commercial catches landed on five
coastal areas in the Gulf of Mexico were sampled. Fifty specimens were exam-
ined from each of Madre Lagoon, Tamiahua Lagoon, Cazones River and Alvarado
Lagoon, and 54 specimens were examined from Mecoac´
an Lagoon (Fig. 1). Spec-
imen identification was based on Thomson (1997), Harrison (2002) and Harrison
et al. (2007). Meristic and seven morphometric characters were measured on the left
México
Gulf of México
Tamiahua Lagoon
Madre Lagoon
Cazones River
Alvarado Lagoon
Mecoacán Lagoon
99° 53′85° 40′
18° 20′
25° 29′
0 100 km
N
50
U.S.A.
n = 50
n = 50 (1)
n = 50 (2)
n = 50
n = 54
Fig. 1. Sampling areas and total number of all species of fishes sampled by area (n). Numbers of specimens
of Mugil hospes in parentheses.
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 78, 386 – 390

388 A. L. IB ´
A˜
NEZ ET AL.
Table I. Morphometric and meristic data of specimens of Mugil hospes capturedintheGulf
of Mexico
Specimens
A-1 A-2 T-1
Morphometrics
LT(mm) 250·0 291·0 288·0
LS(mm) 194·0 233·0 226·0
LH(as % LS)24·3 23·6 22·7
Eye diameter (as % LH)25·4 25·4 27·1
Pectoral fin length (as % LSand LH) 22·9 and 94·321·0 and 89·1 20·8 and 91·6
Snout length (as % LH) 27·5 27·3 27·3
Predorsal fin length (as % LS) 48·5 48·1 48·0
Meristics
Longitudinal scale rows 37 37 39
Transverse scale rows 12 12 13
Anal fin rays III-9 III-9 III-9
Second dorsal-fin rays i-8 i-8 i-8
Pectoral fin rays 14 14 14
A, Alvarado Lagoon; LH, head length; LS, standard length; LT, total length; T, Tamiahua Lagoon.
side of each specimen. The scales of the left flank of the fish were observed under
×10 magnification with a Carl Zeiss stereo compound microscope (www.zeiss.com).
Specimens are now preserved and deposited in the Mugilidae collection of the Uni-
versidad Aut´
onoma Metropolitana-Iztapalapa in M´
exico City.
From the 254 specimens examined, 251 were M. curema (with size range:
158–322 mm LS)and only three were M. hospes (with size range: 194–233 mm
LS), two of which were from Alvarado Lagoon and one was from Tamiahua Lagoon
(Fig. 1). Morphometric and meristic characters of the three specimens of M. hospes
are summarized in Table I. The specimen (A-1) from Alvarado Lagoon is shown
in Fig. 2. Both species have ctenoid scales but with noticeable differences in the
shape of the ctenii. The ctenii of M. hospes are triangular tooth shape [Fig. 3(a)],
whereas the ctenii of M. curema are a flexible rhomboid plaque that appears as a soft
veil [Fig. 3(b)]. These characteristics of the ctenii were found in all the specimens
Fig.2. Mugil hospes 250 mm total length, captured at Alvarado Lagoon (specimen A-1).
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 78, 386 – 390

FIRST RECORD OF MUGIL HOSPES IN THE GULF OF MEXICO 389
(a)
(b)
Fig. 3. Photomicrograph (×10 magnification) of the ctenii of (a) Mugil hospes and (b) Mugil curema.
from all lengths. Accordingly ctenii shape can provide a useful tool to discriminate
between these two species.
Mugil hospes has been reported from Caribbean and western central Atlantic
Ocean waters. According to Harrison (2002), the distribution of M. hospes in the
Atlantic Ocean coastal waters extends from Colombia to Brazil. ´
Alvarez-Lajonchere
(1976) reports this species for Cuban waters of the Caribbean (Tunas de Zaza),
and Thomson (1997) cited M. hospes in the west Atlantic Ocean from Key West,
Florida to Brazil, where specimens examined were from Brazil, Ecuador, Venezuela
and Surinam. No specimens originating from the Gulf of Mexico are present in
the Mexican National Fish Collection from the Institute of Biology (IBUNAM-P),
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 78, 386 – 390

390 A. L. IB ´
A˜
NEZ ET AL.
Universidad Nacional Aut´
onoma de M´
exico at M´
exico City. Therefore, the present
study gives information on the first record of M. hospes from the Gulf of Mexico.
Special thanks to I. J. Harrison for his helpful comments that improved the first version
of this manuscript and to P. Castillo-Galicia and J. Juarez-Flores for assisting in field work.
This study was totally supported by the Universidad Aut´
onoma Metropolitana-Iztapalapa in
M´
exico. M. Gonz´
alez- Castro is supported by Consejo Nacional de Investigaciones Científicas
yT
´
ecnicas (CONICET).
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©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 78, 386 – 390