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Zoologische Abhandlungen (Dresden)
56
: 99–105
99
Gymnogeophagus caaguazuensis
sp. n. - a new species of
cichlid fi sh (Teleostei: Perciformes: Cichlidae) from the
drainage of the lower río Paraguay in Paraguay
W
OLFGANG
S
TAECK
Auf dem Grat 41a, D-14195 Berlin
Abstract
.
Gymnogeophagus caaguazuensis
sp. n. is described from the drainage of the upper
río Tebicuary-mi in the province of Caaguazú in Paraguay. It can be distinguished from all other
described
Gymnogeophagus
species by the following combination of characters: body deep, caudal
peduncle short, caudal fi n of males lyreate, 26–28 scales in a lateral line and small size.
Resumo.
Gymnogeophagus caaguazuensis
, espécie nova, é descrita da drenagem do alto rio
Tebicuary-mi (província Caaguazú, Paraguai).
Gymnogeophagus caaguazuensis
é distinta das
demais espécies descritas do gênero
Gymnogeophagus
pela combinação das seguintes caracteristicas:
corpo relativamento alto, pedúnculo caudal curto, nadadeira caudal dos machos em forma de lira,
26–28 escamas no linha lateral e tamanho pequeno.
Resumen
. Se describe una nueva especie de cíclido,
Gymnogeophagus caaguazuensis
, de la cuenca
del alto río Tebicuary-mi (provincia Caaguazú de Paraguay). La nueva especie se distingue de
todas las demás especies del género
Gymnogeophagus
por la siguiente combinación de carácteres
diagnósticos: cuerpo relativamente alto, pedúnculo caudal corto, aleta caudal de los machos en
forma de lira, 26–28 escamas en la serie longitudinal y talla pequeña.
Kurzfassung
.
Gymnogeophagus caaguazuensis
sp. n. wird aus dem oberen río Tebicuary-mi in
der Provinz Caaguazú in Paraguay beschrieben. Die neue Art unterscheidet sich von allen anderen
bisher beschriebenen
Gymnogeophagus
-Arten durch die Kombination folgender diagnostischer
Merkmale: Körper hoch, Schwanzstiel kurz, Schwanzfl osse der Männchen leierförmig, 26–28
Schuppen in der Längsreihe und geringe Größe.
Key words.
Taxonomy, ichthyology, freshwater, ecology, Cichlidae, new species, Paraguay.
Introduction
The South American cichlid genus
Gymnogeophagus
was fi rst erected by M
IRANDA
-R
IBEIRO
(1918) as a monotypic genus for
G. cyanopterus
(=
G. balzanii
). In 1976 it was reviewed
and redescribed by G
OSSE
who included three additional species. Later R
EIS
& M
ALABARBA
(1988) and R
EIS
et al.
(1992) revised the genus again and rearranged the species. The genus,
which contains medium-sized geophagine cichlids (maximum SL 90–169 mm), is distributed
in the in the southern tropical or subtropical regions of Bolivia, Brazil, Paraguay, Uruguay and
northern Argentina.
The majority of the
Gymnogeophagus
species is endemic to the drainages of both some coastal
rivers in Uruguay and in the states of rio Grande do Sul and Santa Catarina in southern Brazil
and to the river systems of the río Paraguay, río Paraná and río Uruguay. The only exception
is
Gymnogeophagus
balzanii
(P
ERUGIA
,1891), which is also known from the Amazon River
basin, for there is a single record from the río Guaporé, a tributary to the río Madeira (R
EIS
&
M
ALABARBA
, 1988).
The genus
Gymnogeophagus
M
IRANDA
-R
IBEIRO
, 1918 is diagnosed by two derived features, viz.
(1) the possession of a forwards directed spine on the top of the fi rst dorsal-fi n pterygiophore,
and (2) the loss of the bony supraneurals (R
EIS
& M
ALABARBA
, 1988). As currently recognized,
it includes nine nominal species (R
EIS
& M
ALABARBA
, 1988; R
EIS
et al.
, 1992; C
ASCIOTTA
et
al
., 2000), but about a dozen others remain to be described (W
IMBERGER
et al
., 1998; S
TA E C K
,
2001). Some of them are well-known in the aquarium trade and in the popular literature and
© Zoologische Abhandlungen, ISSN 0375-5231, Dresden 15.12.2006
100
S
TAECK
:
S
TA E C K
: New
Gymnogeophagus
from Paraguay
provisionally referred to by popular names. The purpose of the present paper is to give a
formal description of one of these species which brings the total number of described taxa in
the genus to ten and elevates the number of species known from Paraguay to at least three.
Material and Methods
The holotype and paratypes were fi xed in 75% ethanol. The type specimens are deposited in
Staatliches Museum für Tierkunde Dresden (MTD F).
Measurements and counts were taken according to R
EIS
& M
ALABARBA
(1988). Measurements
were made with a dial caliper reading to the nearest 0.1 mm. Numbers in brackets after counts
indicate the number of specimens examined with that condition. Comparisons were made with
specimens of
G. gymnogenys
. Data from the original species descriptions and redescriptions
(H
ENSEL
, 1870; G
OSSE
, 1976; R
EIS
& M
ALABARBA
, 1988) were also used.
Abbreviations
. E1 = row of scales in the horizontal series directly above the longitudinal
row including the lower lateral line; SL = standard length; TL = total length; MTD F = Staat-
liche Naturhistorische Sammlungen Dresden, Museum für Tierkunde, Fischsammlung;
ZMB = Museum für Naturkunde, Berlin.
Gymnogeophagus caaguazuensis
sp. n.
(Figs. 1–3)
Holotype.
MTD F 30367, 84.8 mm SL, male, upper río Tebicuary-mi (approx. 25°28’S,
56°10’W), tributary to río Tebicuary (drainage of the lower río Paraguay), at ruta No. 7 approx.
25 km east of Cnel. Oviedo in the province of Caaguazú in Paraguay,
leg
. February 2005 by
W. S
TAECK
.
Paratypes.
MTD F 30384–30393, 10 specimens (6 males, 4 females), 56.8–86.3 mm SL,
collecting data like holotype.
Non-types.
MTD F 30368–30383, 16 juveniles, 19.8–37.3 mm SL, collecting data like
holotype.
Priv. Coll. S
TA E C K
, 2 females, 70.5 and 58.4 mm SL, collecting data like holotype.
Comparative material.
Gymnogeophagus
gymnogenys
(H
ENSEL
1870): ZMB 7465, 1 male,
125 mm SL, Brazil, rio Grande do Sul, rio Cadeia (Lectotype); ZMB 22299, 4 specimens,
81.6–153.6 mm, collecting data like holotype (Paralectotypes). Priv. Coll. S
TA E C K
, 1 male,
84.4 mm SL, Uruguay, rio Tacuari, 14.2.2000. Priv. Coll. S
TA E C K
, 1 male, 82.5 mm SL,
Uruguay, arroyo Yerbal, 16.2.2000.
Diagnosis
. A small mouthbrooding species of
Gymnogeophagus
with a conspicuous secondary
sexual dimorphism. It differs from all the other described species in the genus in the following
combination of characters: (1) body comparatively deep, (2) caudal peduncle short, (3) caudal
fi n of males lyreate, (4) 26 to 28 scales in E1 row and (5) small size (max. SL 86.3 mm).
Description.
Based on the holotype and 10 paratypes. See fi gs. 1–3 for general shape and colour patterns.
Body proportions are summarized in table 1.
Gymnogeophagus caaguazuensis
is a strikingly dimorphic, rather deep-bodied, robust species
with males being considerably larger, more brightly coloured and developing pointed fi ns and
a tumescent, adipose hump on top of their heads.
Body laterally compressed. In anterior view with keeled nape. Dorsal outline more arched than
ventral outline. In adult males dorsal contour conspicuously divided into two segments with
different degrees of arching: dorsal head contour from snout tip to top of adipose hump very
Zoologische Abhandlungen (Dresden)
56
101
Fig. 1.
Gymnogeophagus caaguazuensis
sp. n., holotype, two months after fi xation, MTD F
30367.
steep and straight (save for small concavity above anterior half of orbit); body contour at base
of dorsal fi n only slightly arched. Ventral head contour with slightly inclined straight lower jaw
and straight sloping posterior section. In females dorsal and ventral outline evenly arched from
snout to last dorsal fi n ray, respectively to fi rst anal fi n ray.
Snout moderately long. Mouth terminal. In upper and lower jaw numerous small uniscupid
conical teeth, which are moderately recurved and not arranged into conspicuous series. Outer
teeth slightly larger than inner ones. Orbit close to forehead contour, all in dorsal half of head.
Dorsal fi n usually originating anterior to vertical line through posterior bony margin of
operculum. Large individuals with pointed prolongation of the soft dorsal fi n, usually
reaching base of caudal fi n. Soft anal fi n of adult males pointed, usually reaching caudal-fi n
base. Pectorals long, usually reaching anal-fi n base. Pelvic fi ns of females roundish, in males
pointed, reaching slightly beyond anus. Caudal fi n in females concave, in males lyrate, deeply
emarginate and with a pointed prolongation of both lobes.
Body scales moderately large and ctenoid, except for cycloid and ctenoid small-scaled pre-
ventral area. Operculum with cycloid and ctenoid scales, usually irregularly scattered. Cheeks
naked or rarely with up to 3 scales. Dorsal fi n, anal fi n, pelvic and pectoral fi ns without scales.
Caudal fi n scaled only at its base.
Teeth of lower pharyngeal tooth plate conical and pointed, not numerous; a few postero-
medial teeth much stronger and with blunt cusps (studied in 2 female non-types of 70.5
and 58.4 mm SL).
External gill rakers on fi rst gill arch: 3–4 epibranchial and 6–7 ceratobranchial (studied in 2
female non-types of 70.5 and 58.4 mm SL).
Dorsal fi n XIII.10 (2), XIII.11 (4), XIV.9 (3), XIV.10 (1) XIV.11 (1). Anal fi n III.7 (1), III.8
(10). Scales in E1 row 26 (3), 27 (5), 28 (3). Scales on upper lateral line: 16 (4), 17 (6), 18 (2);
on lower lateral line 9 (2), 11 (9), 12 (1).
Colouration in life.
Body of adult males with greyish white ground colour. Ventral region
yellowish to deep yellow, forehead and nape tan. Cheeks often with a few irregularly shaped
metallic greenish to golden dots. Upper and frontal part of iris brown. Lips grey. Posterior
part of gill cover often with a tinge of orange. On the body sides several longitudinal series of
scales with a small golden or greenish dot, which form up to eight iridescent thin longitudinal
lines.
102
S
TAECK
:
S
TA E C K
: New
Gymnogeophagus
from Paraguay
Table 1
.
Morphometry of
Gymnogeophagus caaguazuensis
. Measurements of holotype and 10
paratypes in percent of SL (except SL in mm); min = lowest value, max = highest value, mean =
arithmetic mean, sd = standard derivation.
Measurement
min
max
mean
sd
Standard length
56.8
86,3
70.71
Head length
31.7
36.6
34.13
1.57
Snout length
10.7
15.0
12.84
1.47
Body depth
38.0
42.8
40.00
1.47
Eye diameter
8.9
11.4
10.01
0.83
Interorbital width
9.3
13.7
11.83
1.26
Preorbital depth
8.2
11.9
9.96
1.25
Caudal peduncle depth
13.3
14.9
13.97
0.59
Caudal peduncle length
13.9
17.4
15.92
0.99
Pectoral fin length
27.3
33.8
30.90
1.80
Last dorsal fin spine length
11.0
13.3
12.09
0.81
Frequently with a dark infraorbital stripe from the eye to the corner of the preopercle and a
dark supraorbital stripe from eye to eye. In the middle of the fl anks a large black rectangular
lateral blotch extending dorso-ventrally from the upper lateral line to the scales 6 or 7 to 9 or 10
in E1 row. An irregular dark horizontal lateral band from gill cover to caudal spot is interrupted
both behind the lateral blotch and in front on the caudal peduncle. In adult specimens vertical
bars usually reduced to a large blotch in front of the origin of the dorsal fi n and another above
the lateral blotch.
In adult males caudal fi n yellowish with broad red margins and irregularly arranged silvery
or bright blue roundish dots. Soft portion of dorsal fi n red with silvery to bright blue dots.
Proximal portion of anal fi n yellow, distal portion deep red with well-defi ned silvery to bright
blue dots. Ventral fi ns reddish with several bluish longitudinal streaks. Pectoral fi ns hyaline.
Colouration of female specimens similar but more pallid.
Colouration in alcohol.
Dark markings well preserved, but general appearance of preserved
specimens paler. Iridescent marks and bright blue dots become white, red pigmentation
becomes pale brown. The ventral orange colouration becomes whitish.
Geographical distribution.
At present
Gymnogeophagus caaguazuensis
is known only from
the type locality in the drainage of the lower río Paraguay in the province of Caaguazú in
Paraguay.
Ecological notes.
Field observations at the type locality indicate that the habitats preferred by
Gymnogeophagus
caaguazuensis
are bare sandy bottoms among rocky areas in small rivulets
which may have a strong current during the rainy season. But during the dry season and the
period of low water this species is found in pools and ponds with more or less stagnant water.
Water data collected in February at the type locality: pH 7.9; electrical conductivity 240 µS/cm;
water temperature 24.2 °C. The associated fi sh fauna included
Phalloceros caudimaculatus
(Poeciliidae),
Rineloricaria
sp. (Loricariidae) and two small characid species.
Reproductive behaviour.
Gymnogeophagus
species display a variety of parental care and
mating systems ranging from mouthbrooding and polygyny to substrate spawning and
monogamy. Breeding was observed in aquarium:
Gymnogeophagus caaguazuensis
is a
Zoologische Abhandlungen (Dresden)
56
103
3
2
3
Fig. 2.
Live
topotypic adult male of
Gymnogeophagus caaguazuensis
sp. n., approx. 10 cm TL,
photographed in aquarium; not preserved.
Fig. 3.
Live topotypic adult female of
Gymnogeophagus caaguazuensis
sp. n., approx. 8 cm TL,
photographed in aquarium; not preserved.
delayed (larvophile) maternal mouthbrooder. Like several of its congeners this species starts
reproduction like a substrate spawner, i. e. the parents initially spawn on a stone. But just prior
to the hatching of the larvae the female picks up the eggs and then orally broods the larvae
and young.
In front of ripe females courting males display a conspicuous quivering movement of their
mouths caused by opening and closing the mouth with extremely high frequency. This
peculiar behaviour during courtship seems to be a synapomorphy of the mouthbrooding
Gymnogeophagus
species, as it has been observed only within this species complex (S
TA E C K
,
2003).
Etymology.
The specifi c epithet
caaguazuensis
refers to the province of Caaguazú in Paraguay,
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