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FOUR NEW SPECIES OF RIVULUS POEY, 1860,
SUBGENUS CYNODONICHTHYS MEEK, 1904
(TELEOSTEI: CYPRINODONTIFORMES: RIVULIDAE)
FROM THE MAGDALENA RIVER BASIN, CENTRAL
COLOMBIA, INCLUDING NOTES ON RIVULUS
(CYNODONICHTHYS) ELEGANS STEINDACHNER, 1880.
Four new species of Rivulus Poey, 1860, subgenus Cynodonichthys Meek, 1904
(Teleostei: Cyprinodontiformes: Rivulidae) from the Magdalena River Basin, Central
Colombia, including notes on Rivulus (Cynodonichthys) elegans Steindachner, 1880.
Frans B. M. Vermeulen *
ABSTRACT.
Four new rivulid species are described: Rivulus (Cynodonichthys) azurescens,
Rivulus (Cynodonichthys) pivijay, Rivulus (Cynodonichthys) ribesrubrum, and
Rivulus (Cynodonichthys) xi. Rivulus azurescens and R. ribesrubrum belong to the
R. elegans species-group. Rivulus pivijay and R. xi are closely related to the R.
elegans species-group, but differ by: 1) a unique reticulate brown color pattern on
the body (versus a pattern of red longitudinal stripes); 2) males with the caudal-fin
without a yellow/orange posterior border (versus males with a yellow/orange
posterior border); and 3) the presence of an ocellus (faint or weak in adult males)
on the caudal peduncle in both sexes (versus absence of an ocellus in both sexes,
except in females of R. magdalenae and R. boehlkei. Huber & Fels 1985. Some
notes concerning R. (Cynodonichthys) elegans Steindachner, 1880 are included for
comparison.
Key words : taxonomy, Rivulus (Cynodonichthys) azurescens, elegans, pivijay,
ribesrubrum, xi, new species, Central Colombia
* Tanki Leendert 194c, Aruba. E-mail: vermeulen@setarnet.aw
INTRODUCTION.
The richness and diversity of the Neotropical rivulid killifish fauna is emphasized by
the continuing discovery and description of new species. Many of these novelties are from
newly explored areas that were previously inaccessible. However, some, like the present
subjects, are from regions whose fish faunas were (partially) sampled years earlier, but
where subsequent, more intensive field collections had been curtailed by prolonged
periods of political instability.
The New World Killifish genus Rivulus Poey, 1860 is represented by the
assemblage also known as the Rivulus elegans species group, in the river systems of
Central Colombia and the southern half of Panama. Species of this assemblage occur in
small mountain streams with clear water under the cover of primary forest up to 1,300 m
altitude. The Rivulus elegans species-group comprises six members considered as valid:
R. boehlkei Huber 1992, Rio La Miel, Caldas Dpt. Colombia; R. chucunaque Breeder
1925, from the Chucunaque River, Darien Province, Panama; R. elegans Steindachner
1880, near Cáceres, Rio Cauca, Rio Magdalena basin, Antioquia, Colombia; R. leucurus
Fowler 1944, from the upper Rio Juradó, North-West Colombia; R. magdalenae
Eigenmann & Henn, in Henn, 1916, from Ibagué, upper Rio Magdalena, Colombia and R.
pacificus Huber 1992, from the Rio Condoto, Choco Dpt., Colombia, Rio San Juan Basin.
Members of the R. elegans species group belong to the subgenus Cynodonichthys, which
currently includes 27 species (Costa, 2011) from Central America and Trans-Andean
South America. The subgenus includes medium to large-sized species, reaching between
50 and 80 mm SL, with short fins, usually rounded (the caudal fin is truncate in a few
species).
Costa (2011) divided Rivulus into six genera (some previously considered to be
subgenera). The proposed classification was: Atlantirivulus Costa, 2008, Anablepsoides
Huber, 1992, Cynodonichthys Meek, 1904 (including the subgenus Vomerivulus Fowler,
1944 if valid), Melanorivulus Costa, 2006, Laimosemion Huber, 1999 (with the sub genus
Owiyeye Costa, 2006) and Rivulus Poey, 1860. Rivulus comprises only two species from
Cuba, and a third species of still uncertain status, Rivulus roloffi Trewavas, 1948 from
Hispaniola in the Caribbean Sea. A seventh genus, Kryptolebias Costa, 2004 was well
established.
Huber (2012) suggested that Costa’s (2011) proposal was premature. The
combined set of mitochondrial and morphologic data was questionable. Huber maintained
Rivulus as a single genus. His scientific work (Huber 2012) was based on 144 external
characters which resulted in 3 trees only, very much in line with the global stability of
major lineages and the consensus tree produces bootstrap values that are much higher
than previously released studies with morphological and osteological characters, while
continuing to recognize Kryptolebias as a separate genus. The present author follows the
conclusions by Huber.
This article describes four species of the genus Rivulus Poey, 1860 and the
subgenus Cynodonichthys Meek, 1904 (both terms sensu Huber, 2012 - not sensu Costa,
2011). They are described from specimens collected in Central Colombia in 2008 and
2009. That fieldwork also yielded topotypical specimens of the virtually unknown Rivulus
elegans Steindachner, 1880. Apparently, no other correctly identified specimens of this
species have been reported since the type series was collected in 1878 (Huber, 1992:
190 – 192). Some aspects of its biology, including life colors, are reported here for the first
time. These observations provide a comparative basis for the recognition of specific novel
features of each of the four new taxa.
All four new species are referred to Huber’s (1992) “Rivulus elegans species group.”
Except for R. pivijay, they all inhabit small, clear - running mountain streams under
primary forest canopy at altitudes of up to about 1300 m, a habitat they share with R.
elegans and with some populations of the two best - known members of the R. elegans
group, R. magdalenae Eigenmann & Henn and R. chucunaque Breder. The description of
R. pivijay and R. xi as members of the Rivulus elegans group widens the set of
characteristics so far specific to the Rivulus elegans group, bearing a white or orange
caudal distal band in males as these characters are not present in both new species.
(Huber 1992).
MATERIALS AND METHODS.
Morphology and meristics. Measurements and counts follow Huber (1992).
Measurements are tabulated as percentage of standard length (SL). Measurements were
taken with a digital Mitutoyo caliper and are rounded off to one tenth of a millimeter. Fin-
ray counts include all elements. Terminology for frontal squamation follows Hoedeman,
1958. Material was deposited at the Alexander von Humboldt Institute, Bogotá, Colombia
under the acronym IAvH-P (IAvH-P = Instituto de Investigación de Recursos Biológicos
Alexander von Humboldt, Bogotá, Colombia). Additional material was donated to RMNH
(ZMA), Naturalis, Nationaal Natuurhistorisch Museum, Leiden, The Netherlands (formerly
named Rijksmuseum van Natuurlijke Historie). For some species only a small number of
specimens was available to the author for a technical description, due to unpredictable
adverse circumstances.
DESCRIPTIONS.
Rivulus (Cynodonichthys) elegans Steindachner, 1880
(Fig. 1, Table 1)
Fig. 1: Rivulus (Cynodonichthys) elegans. Pair, upper male, lower female. Collected near
Cáceres, Taraza at field nr. COL 2009-08. Specimens not preserved.
Topotype: IAvH-P 11254, male 58.3 mm SL,: Quebrada La Cristalina, a small tributary to
the Cauca River near Cáceres, Antioquia Dpt., Colombia. Tiny tributary stream at the
opposite side of the creek near the local school football field. Coordinates: 7°35’55”N
75°19’15”W. Field nr. COL 2009-07. Collected by F.B.M. Vermeulen and F. A. Correa –
Polo, June 25, 2009.
Topotype: RMNH.PISC.36363, male, 53.2 mm SL: Taraza, Antioquia Dpt., Colombia. On
the route from Cáceres to Medellin, 6 KM after passing Taraza at kilometer mark 112, a
steep cascading mountain creek coming down from a massive rock wall. Coordinates:
7°30’00”N. 75°20’43”W. Field nr. COL 2009-08. Collected by F.B.M. Vermeulen and F. A.
Correa – Polo, June 26, 2009.
Diagnosis: Rivulus elegans is distinguished from its group members in Central Colombia
by having the following combination of characters: Except for R. azurescens, Rivulus
elegans show a more slender and elongated body as expressed by the low average body
depth at anus level to the SL (19.4 % vs. 19.7-22.6 %) compared to other relatives, except
for Rivulus chucunaque, described herein.
Rivulus elegans further differs in color from others in the group by having light brownish
body with orange dots forming continuing lines vs. blue body and dark red dots not
forming continuing lines in R. ribesrubrum and R. azurescens and brownish irregular
markings in R. pivijay and R. xi, by overall hyaline yellow- to greenish unpaired fins
without pigmented margins vs. more colored fins with marginal- or sub marginal bands in
R. azurescens and R. xi, by the absence of a caudal spot in all stages of life vs. the
presence of a caudal spot in R. magdalenae (female only) and in both sexes in R.
boehlkei, R. pivijay and R. xi.
Huber (1992) considers Rivulus elegans closely related to Rivulus chucunaque Breder
1925 from Panama but R. elegans has more scales LL (39-40 vs. 35 – 36) than R.
chucunaque, more minute scale rows on caudal-fin base (6-7 rows vs. 3-4 rows), pelvic
fins reaching anal-fin base in males vs. pelvic fins reaching not beyond genital opening in
males, R. elegans differs substantial in body- and fin color pigmentation with R.
chucunaque (orange spots forming broken lines on body and hyaline unpaired fins, vs.
pink to tomato red spots on each scale in combination with densely red spots in unpaired
fins). Both taxa, but also the related R. sucubti (if valid) and R. leucurus share the whitish
rear border in the caudal-fin, medium size, rather slender shape and bearing irregular red
dots on the body. (Huber 1992)
Description: Morphometric and meristic characters of 2 topotypes are presented in Table
1. Largest individual examined 53.2 mm SL; dorsal profile slightly convex from snout to
dorsal fin, almost straight on caudal peduncle; ventral profile slightly convex from lower
jaw to posterior of anal-fin base, almost straight along caudal peduncle; body slender,
cylindrical anteriorly, more compressed posteriorly; greatest body depth well before
ventral-fin insertion. Dorsal fin triangular with a disruption close to insertion, in males more
rounded and slightly shorter in females; anal-fin rectangular in males, rounded in females,
caudal truncated with rounded edges in males, a little smaller and more rounded in
females, pectorals rounded in both sexes, more elongated in males; pelvic-fin in males
reaching second anal-fin rays, slightly shorter in females reaching not beyond base anal-
fin insertion; interspace between pelvic-fins small (less than 1mm). Mouth opening
dorsally oriented; dorsal origin in a vertical through base between ninth and tenth anal-fin
ray; dorsal-rays 9-10; anal-rays 15-16; pelvic-rays 7-8; pre-dorsal length from tip of snout,
71.5 – 74.8 % of SL (average 73.1); scales large, cycloid; body and head entirely scaled
with exception of cheek; scales cover 40 % of the surface of the caudal-fin base; frontal
squamation E-type, frontal scales circularly arranged around A-scale without free margins;
E-scales full exposed; longitudinal series of scales from gill cover to posterior end of
hypural plate 39-40 + 6-7 rows of scales at the base of caudal covering about 40% of the
caudal-fin length; transverse series of scales 10; scale rows around caudal peduncle 18;
number of vertebrae 33; epipleural ribs not bifurcated. Sensory organs, supra-orbital
posterior series: 3 neuromast pairs, in 2 V-shaped grooves; 2 sensory organs in mandible
series; 2 sensory organs, supra-orbital lateral series: in 2 continuous straight grooves;
Pre-orbital (lacrimal) sensory organs series: no pores but isolated buttons; Post-orbital
sensory organs series: an un-counted series of small buttons.
Table 1: Morphometric and meristic characters of Rivulus (Cynodonichthys) elegans.
Topotype Topotype largest smallest average
in mm in % SL % SL % SL % SL
n=4 n=4 n=4
Measurements
Total length (mm) 58.3 119.7 65.0 44.2 56.3
Standard length (mm) 48.8 100.0 53.2 36.1 46.7
Pre-dorsal length 72.1 74.8 71.5 73.1
Pre-anal length 61.6 62.2 58.3 60.1
Length of dorsal-fin base 13.5 13.5 9.4 11.2
Length of anal-fin base 22.5 22.5 21.2 21.7
Pelvic-fin length 9.1 9.3 7.9 8.7
Body depth 19.7 21.1 18.3 19.4
Caudal- peduncle depth 13.4 14.8 11.3 12.9
Head length 26.8 26.8 24.2 25.5
Counts
Dorsal-fin rays 10 10 9 9.5
Anal-fin rays 16 16 15 15.3
Pelvic-fin rays 8 8 7 7.8
Dorsal to Anal position 10 10 9 9.8
Meristic
Scales in longitudinal series 39 40 39 39.3
scales on caudal fin base 6 7 6 5.3
Scales in transversal series 10 0 0 0.0
Colors in life: Male. Body overall light brown to golden, towards the dorsal region darker.
At the sides a faint purple hue is present. The purple is a bit deeper towards the peduncle.
The ventral side of the body pale white. Seven lines of tomato red spots cover the sides of
the body, the upper line merely unbroken the others with series of spots forming broken
lines, lines towards the ventral part more disrupted. Cheeks pale white. Gill covers brown
with some tomato red markings and soft blue center. Reticulate markings posterior to the
gill covers absent. Eyes with yellow-brown iris, more bright yellow during courtship. Pelvic
fins soft yellow-green without markings towards the base with bluish hue. Anal fin same
ground color as pelvic fins but with some red dots scattered on the bluish part at the base.
Dorsal dusk green with large number of red spots forming a pattern of lines near the base
and dotted lines in the remaining posterior part of the dorsal. None of the unpaired fins
show a distinct colored marginal band but have a weak darker color towards the edges.
Pectorals hyaline yellowish, transparent without any markings; caudal golden yellow with
a distinct whitish- to pale orange band at the posterior margin. On the caudal base the
lines on the body transforms in a number of small orange spots fading into very fine
orange speckles towards the center of the caudal fin. An indistinct trace of a dark upper-
and lower margin of the caudal is visible. No supracaudal ocellus, or so-called Rivulus
spot, is present on the peduncle at any stage of life.
Female. Similar to male but subdued. Body light brown with a pale blue shine, the light
brownish color to the dorsal more darkening. The seven lines on the sides of the body
containing fewer dots and these dots have an orange color, not red, or not as red as in
males. Dorsal hyaline with some brown dots at the base only. Anal close to the base
bluish with some orange speckles, further green–yellow without any trace of marginal
band. Pelvic fins with green hue. Caudal at the base yellow to the center hyaline green.
No markings on caudal-fin except for a few small spots at the base. No supracaudal
ocellus, or so-called Rivulus spot, is present on the peduncle at any stage of life.
Rivulus (Cynodonichthys) azurescens new species
(Figs. 2-3, Table 2)
Fig: 2. Rivulus (Cynodonichthys) azurescens, male from type locality. Specimen not
preserved.
Fig: 3. Rivulus (Cynodonichthys) azurescens, female from type locality. Specimen not
preserved.
Holotype: IAvH-P 11255: male 56.6 mm SL.; Little mountain creek, 4 kilometer before
entering Doradal, on the left side of the auto route nr. 60 coming from Medellin in direction
Puerto Triunfo, Antioquia department, Colombia. The creek is opposite the entrance of
Rancho San Silvestre. Coordinates 5°54”93’N 74°46”85’W, altitude 353 m., collected by
F.B.M. Vermeulen & F.A. Correa-Polo, February 19, 2008.
Paratype: one female, RMNH.PISC.36364, 28.2 mm SL: Little mountain creek, 4
kilometer before entering Doradal, on the left side of the auto route nr. 60 coming from
Medellin in direction Puerto Triunfo, Antioquia department, Colombia. The creek is
opposite the entrance of Rancho San Silvestre. Coordinates 5°54”93’N 74°46”85’W,
altitude 353 m., collected by F.B.M. Vermeulen & F.A. Correa-Polo, February 19, 2008.
Diagnosis: Rivulus azurescens n. spec. is distinguished from its group members in having
the combination of following features: R. azurescens has lower number of dorsal-fin rays
(9-10 vs.11 for R. ribesrubrum), higher number of anal-fin rays (16 vs. 13-14 for R.
pivijay), lower number of scales LL (35-36 vs. 39-40 in R. elegans and R. ribesrubrum)
and (41-42 in R. xi). R. azurescens has largest number of scale-rows at caudal peduncle
(7-8 vs. 4-7 in all group members), males of R. azurescens differ from all group members
by the deep azure-blue color on the flanks, the aubergine reticulated pattern with yellow
distal band in dorsal, the marbled red pattern on blue at the basis in anal-fin and the
intense orange color at upper and rear borders of the caudal. Females do show the same
azure body color as in males - but subdued - with red spots vs. yellow-brown body with
orange spots in R. elegans and R. ribesrubrum and marbled brown body without colored
spots in R. pivijay and R. xi. Females also differ remarkably in fin coloration by showing
marginal- and sub marginal borders in pelvic- anal- and caudal fins vs. absent marginal-
and/or sub marginal borders in any fin of other group members.
Description: Morphometric and meristic characters of types are presented in Table 2.
Largest individual examined 56.6 mm SL; dorsal profile slightly convex from snout to
dorsal fin, almost straight on caudal peduncle; ventral profile convex from lower jaw to
posterior of anal-fin base, almost straight along caudal peduncle; body slender, cylindrical
anteriorly, more compressed posteriorly; greatest body depth well before ventral insertion;
dorsal fin triangular with a disruption close to insertion, in males more rounded and slightly
shorter in females; anal fin rectangular in males rounded in females; caudal truncated with
rounded upper edge in males, a little smaller and more rounded in females; pectorals
rounded in both sexes, more elongated in males; pelvic fin in males reaching second
anal-fin rays, slightly shorter in females reaching not the base anal-fin insertion;
interspace between pelvic fins small (less than 1mm.) Mouth opening dorsally oriented.
Dorsal origin in a vertical through base between ninth and tenth anal-fin ray; dorsal rays
10; anal rays 16; pelvic rays 7; pre-dorsal length from tip of snout, 72.5 – 74.7 % of SL
(average 73.9); scales large, cycloid; body and head entirely scaled with exception of
posterior part of the lower jaw; frontal squamation E-type, frontal scales circularly
arranged around A-scale without free margins, E-scales full exposed; largest sample
examined (Holotype) had a damaged / malformed frontal squamation; longitudinal series
of scales from gill cover to posterior end of hypural plate 35-36 + 7-8 rows of scales at the
base of caudal covering about 45% of the fin length; transverse series of scales 10;
number of vertebrae 33; epipleural ribs not bifurcated; sensory organs, supra-orbital
posterior series: 3 neuromast pairs, in 2 V-shaped grooves; 2 sensory organs in mandible
series; 2 sensory organs, supra-orbital lateral series in 2 continuous straight grooves; pre-
orbital sensory organs series: no pores but isolated buttons; post-orbital sensory organs
series: an un-counted series of small buttons.
Table 2: Morphometric and meristic characters of Rivulus (Cynodonichthys) azurescens
new species.
Holotype Holotype largest smallest
in mm in % SL in % SL in % SL
n=2 n=2
Measurements
Total length 67.6 120.9 70.5 67.6
Standard length 55.9 100 55.9 55.8
Pre-dorsal length 72.6 75.4 72.6
Pre-anal length 60.7 63.2 60.7
Length of dorsal-fin base 13.1 13.4 13.1
Length of anal-fin base 22.4 22.4 21.3
Pelvic-fin length 9.9 11.3 9.9
Body depth at anus level 20.6 24.5 20.6
Caudal- peduncle depth 14.3 15.8 14.3
Head length 25.1 28.6 25.1
Counts
Dorsal-fin rays 11 11 11
Anal-fin rays 17 17 16
Pelvic-fin rays 9 9 8
Dorsal to Anal position 10 10 9
Scales
Scales in longitudinal series 41 41 39
scales on caudal fin base 7 7 6
Scales in transversal series 10 10 10
Colors in life: Male. Dorsal side of the body dark brown, azure blue laterally, pale purple
ventrally, orange dots forming 7 - 8 clear horizontal lines laterally over the body, less
intense towards the ventral region; dorsal portion of head and lower jaw dark brown; post
orbital region bluish ; opercula with yellow- golden mark anterior the pectoral fin insertion;
chin bluish-grey ; eye iris brown- golden; the lower half and center of the dorsal fin has a
pattern of aubergine red markings forming horizontal lines, more posterior fading in spots,
the upper part is orange-golden with a thin black margin; anal fin is blue at the basal half
with red irregular markings and spots, pale yellow for the remaining part showing a
marginal band of faint orange black pigment along the lower border; caudal in center grey
with green- yellow speckles, the anterior margin shows a broad band of orange that
continues along the dorsal part, forming an orange sub margin with a faint black marginal
band. The lower margin of the caudal shows a broad black margin; pectorals hyaline with
orange at the base; pelvic fins blue with some red speckles at the base, an orange band
at the distal part with an aubergine margin. A Rivulus-spot is absent in all stages of life.
Female. Dorsal side of the body dark brown, purple to blue laterally, pale purple to white
ventrally, small orange dots forming 7 - 8 broken horizontal lines laterally ending at the
peduncle region; dorsal portion of head and lower jaw dark brown; post orbital region
bluish ; opercula with yellow-golden marking anterior the pectoral-fin insertion; chin bluish-
grey; eye iris brown-golden; dorsal fin hyaline whitish with faint brown speckles more
concentrated to the base, no marginal lines; anal fin is whitish blue at the basal portion, no
distinct markings, greenish in the central part with red-brown sub marginal line and black
margin border; caudal hyaline green at center, borders show faint orange sub marginal
band with black outer border; pectorals hyaline some orange at the base; pelvic fins
hyaline with bluish shine, orange sub marginal line and black border. A Rivulus spot is
absent in all stages of life.
Reproduction: The adult female can produce an average of 10-15 eggs daily. Spawning at
top of substratum. Eggs have a moderate to large diameter of 1.9 – 2.1 mm., amber
colored, chorion without filaments but with clusters of adhesive fibers. Development time
16 – 20 days.
Distribution and habitat: Known only from the type locality, numbered with field nr. COL
2008-11, a steep mountain creek under primary forest canopy, clear swift running water,
stony cascading profile, no aquatic vegetation, temperature 20 °C at 19.45 hours, pH 5.8.
The creek is situated along the auto route from Medellin to Puerto Triunfo, about 4
kilometers before Doradal and opposite from the entry of a ranch with the name “Rancho
San Silvestre”.
Etymology: The name of the new species is referring to the iridescent reflecting “azure
blue” color on the sides in males and in a lesser degree also in females.
Rivulus (Cynodonichthys) pivijay new species
(Fig. 4-5: Table 3)
Figure 4: Rivulus (Cynodonichthys) pivijay – male. Near Pivijay village, Magdalena Dpt.,
Colombia. Specimen not preserved.
Figure 5: Rivulus (Cynodonichthys) pivijay – female. Near Pivijay village, Magdalena
Dept., Colombia. Specimen not preserved.
Holotype: IAvH-P: 11257, male 48.1 mm SL; 2 Paratypes, one female 40.7 mm, one male
36.1 mm collected with Holotype, Magdalena Department, Northern Colombia; south from
Ciénaga Grande de Santa Martha; swamp on 28.3 km at the right side of the road from
Fundacion to Pivijay; 10°28’25”N - 74°26’45”W, altitude 7 m., collected by F.B.M.
Vermeulen & F.A. Correa-Polo, March 1, 2008.
Paratypes: one male, RMNH.PISC.36365, 46.6 mm SL: Collected with holotype,
Magdalena Department, Northern Colombia; south from Ciénaga Grande de Santa
Martha; swamp on 28.3 km at the right side of the road from Fundacion to Pivijay;
10°28’25”N - 74°26’45”W, altitude 7 m., collected by F.B.M. Vermeulen & F.A. Correa-
Polo, March 1, 2008.
Diagnosis: Rivulus pivijay n. spec. is distinguished from all other known Central
Colombian group members in having the combination of following features: Lower range
LL scales (34 - 36 vs. 41- 42 in Rivulus xi and 39 – 41 in all others within the central
Colombian clade). Rivulus pivijay has relative high pre-dorsal length (71.5 -77.9 vs. 70.6 -
74.8) compared to the other taxa described herein; lower number of anal-fin rays (13-14
vs. 14-16 in Rivulus elegans and Rivulus xi, 15-16 in Rivulus magdalenae, 16-17 in
Rivulus azurescens and Rivulus ribesrubrum); lowest number of vertebrae (31 vs. 33-36);
unique tomato red color in unpaired fins in males and a reticulated strong melanistic
pattern on flanks of females, not seen in any other of its clade members; bearing a
Rivulus spot in males (juvenile and sub-adults) and in females in all stages of life, a
feature shared only by Rivulus xi and females of R. magdalenae and R. boehlkei and not
by any of the others in the elegans group and by the absence of a white - or orange distal
band in the caudal in males, a feature shared by Rivulus xi only. In general Rivulus pivijay
reaches smaller SL and is more compact in the body than Rivulus xi, based on DNA
sequences not included in this work, genetically its closest relative. Largest sample
measured: SL 48.1 mm. vs. SL 57.9 mm. for Rivulus xi.
Description: Morphometric and meristic characters of Holotype and Paratypes presented
in Table 3. Largest specimen examined 48.1 mm SL.; body cylindrical, at first impression
rather compact, posterior more compressed at level of caudal peduncle; dorsal and
ventral profile a little convex; caudal peduncle at upper and lower profile nearly straight,
peduncle relatively short; snout blunt and short; mouth opening dorsally oriented; eyes
positioned on upper portion of the head sides. Dorsal and anal fins all rounded, slightly
more pointed in males, all without filaments; anal fin embedded somewhat in the lower
body line; dorsal fin origin at vertical trough base of anal fin-rays 9
th
- 10
th
; pectoral fins
rounded, more elongated in males; pelvic fins short, longer in males reaching the first
anal-fin ray in males, reaching the urogenital opening in females, positioned on the
outermost lower bodyline and with minimal interspace, less than 1 mm. in both sexes;
caudal truncated, in males slightly longer than in females; dorsal-fin rays 8-9, anal-fin rays
13-14, pelvic-fin rays 6 - 7.; frontal squamation E – type; longitudinal series of scales 34-
36, on caudal 4-5 rows covering approximately 20 % of the caudal fin length; transverse
series 9-10; number of vertebrae 31; epipleural ribs not bifurcated. Sensory organs,
supra-orbital posterior series: 3 neuromast pairs, in 2 V-shaped grooves; 2 sensory
organs in mandible series; 1 sensory organ supra-orbital lateral series: in 1 continuous
straight grove; pre-orbital sensory organs series: no pores but isolated buttons; post-
orbital sensory organs series: an un-counted series of small buttons.
Table 3: Morphometric and meristic characters of Rivulus (Cynodonichthys) pivijay new
species.
Holotype Holotype largest smallest average
in mm in % SL in % SL in % SL in % SL
n=4 n=4 n=4
Measurements
Total length 58.3 121.1 58.3 44.9 42.1
Standard length 48.1 100.0 48.1 36.1 42.9
Pre-dorsal length 73.2 77.9 73.2 75.8
Pre-anal length 61.2 62.3 58.7 60.7
Length of dorsal-fin base 10.7 12.5 8.5 10.3
Length of anal-fin base 19.8 21.0 19.8 20.2
Pelvic-fin length 10.2 10.2 7.8 8.8
Body depth at anus level 20.0 21.2 18.1 19.7
Caudal- peduncle depth 13.8 13.9 12.7 13.3
Head length 25.2 25.6 23.6 24.7
Counts
Dorsal-fin rays 9 9 8 8.3
Anal-fin rays 13 14 13 13.8
Pelvic-fin rays 7 7 6 6.8
Dorsal to Anal position 10 10 9 9.8
Scales
Scales in longitudinal series 35 36 34 34.8
scales on caudal fin base 5 5 4 4.8
Scales in transversal series 10 10 9 9.8
Colors in life: Male. Dorsal side of the body dark to greenish brown, purple blue laterally,
bluish to white ventrally, brown blotches starting posterior to the gill-cover form a broken
line along the dorsal part of the body, more towards the mid-section of the body more
brown spots form a set of 5 to 6 irregular lines, this arrangements of lines is not constant
in all individuals and can vary; ventral portion of body scales have pale red and blue
colors without clear markings; dorsal portion of head and lower jaw dark brown; opercula
golden with blue blotch anterior of the pectoral fin insertion; chin bluish-grey; eye iris
golden; dorsal-fin has red blotches at the base, more to the tip transformed in broken lines
on reddish background; anal at the base portion blue, fading into brown-red and further
down to the margin fading in black, some red spots are spread out near the base not
forming lines; anal-fin is red-brown with red elongated markings following the fin rays and
with in-between some red spots, dorsal portion more hyaline red, outer part fading to
black; ventral fins hyaline, bluish at the base more black at the distal part with a faint black
margin along the first ray and small red dots not forming a pattern; pectorals hyaline with
orange at the base. In juvenile and sub-adult males a so-called Rivulus spot is present
which disappears in full adult males only during state of excitement.
Female. Side of body grey to light brown, scales with dark- brown blotches forming
irregularly zig-zag markings; dorsum, head and lower jaw dark brown; ventral portion also
with dark brown markings on grey background; chin bluish grey to white, post orbital
region with dark brown markings, mid portion opercula golden with green blotch anterior
pectoral fin insertion; eye iris brown- golden; dorsal-fin hyaline with faint brown speckles,
no marginal lines; anal hyaline green with weak brown spots at the base, not forming
lines, no marginal lines; caudal hyaline with yellowish shine large number of black spots,
larger at the center, smaller towards the margins; a dark circular Rivulus spot is situated
at the dorsal side on the caudal peduncle near the base of the caudal-fin and is
surrounded completely by a whitish border, at the dorsal part of the peduncle a number of
fine black speckles is present; pectorals hyaline yellow; ventral fins hyaline with bluish
shine, no markings or marginal lines.
Reproduction: The adult female can produce an average of 8-10 eggs daily. Spawning at
top of substratum. Eggs have a moderate to large diameter of 1.8 – 2.0 mm., amber
colored, chorion without filaments but with clusters of adhesive fibers. Ready to hatch in
16 – 20 days.
Distribution and habitat: Known only from the type locality, a swamp, heavily filled with
aquatic plants and grasses, along the side of the road between Fundacion and Pivijay
Coordinates 10°28’25”N –74°26’45”W, altitude 7 meters above sea level, temperature
26°C at 9.30 hours PM, pH 5.85
Etymology: The new species is named after the village Pivijay, south from the Ciénaga
Grande de Santa Marta, Magdalena Department, Northern Colombia where the species
was discovered. The name Pivijay is said also the local name of the “Small- leaf Rubber
plant: Ficus benjamina Fam. Moraceae, that is known from this area. The species was
distributed among hobbyists under the field code: COL 2008-28 – Rivulus species
“Pivijay”.
Rivulus (Cynodonichthys) ribesrubrum new species
(Figs. 6-7: Table 4).
Fig: 6. Rivulus (Cynodonichthys) ribesrubrum - male from type locality Rio La Miel, Caldas
Dpt. Colombia. Specimen not preserved.
Fig: 7. Rivulus (Cynodonichthys) ribesrubrum - female from type locality Rio La Miel,
Caldas Dpt. Colombia. Specimen not preserved.
Holotype: IAvH-P 11256, male 55.9 mm SL.; Upper Rio La Miel, small clear water creek,
tributary to right bank of Rio La Miel. San Miguel, Caldas Dpt. Central Colombia.
Coordinates: 5°36’28” N – 74° 99’35” W. Altitude 290 meter, collected by F.B.M.
Vermeulen and F. A. Correa - Polo. February 20, 2008.
Paratype: RMNH.PISC.36366, male 55.8 mm SL.; Upper Rio La Miel, small clear water
creek, tributary to right bank of Rio La Miel. San Miguel, Caldas Dpt. Central Colombia.
Coordinates: 5°36’28” N – 74° 99’35” W. Altitude 290 meter, collected by F.B.M.
Vermeulen and F. A. Correa - Polo. February 20, 2008.
Diagnosis: Rivulus ribesrubrum n. spec. is distinguished from other group members from
Central Colombia in having the combination of following features: R. ribesrubrum has high
counts on dorsal-fin rays (11 vs. 8-9 in R. pivijay and R. xi), (9 in R. boehlkei), (9-10 in R.
elegans and 10 in R. azurescens); highest number of anal-fin rays (16-17 vs. 13-14 for R.
pivijay having the lowest). Males Rivulus ribesrubrum differs in color by the soft blue shine
on the flanks and the scattered red dots not forming lines vs. blue body having red lines of
dots in R. azurescens and R. elegans and a dark melanistic pattern in R. pivijay and R. xi.
Females have a yellow-brown basis color with orange dots that is shared with R. elegans
and Rivulus chucunaque females but differs from all other group members that are known
alive.
Description: Morphometric and meristic characters of Holotype and Paratypes presented
in Table 4. Largest specimen examined 55.9 mm SL., body cylindrical, at first impression
rather compact, posterior more compressed at level of caudal peduncle; dorsal and
ventral profile slightly convex, caudal peduncle at upper and lower profile nearly straight,
peduncle relatively short; snout short equal to eye diameter; mouth opening upwards
oriented; eyes positioned at midlevel of mouth-opening; dorsal and anal-fin all rounded,
slightly more pointed in males, all without filaments; anal-fin positioned at the lower body
line not embedded; dorsal fin origin at vertical trough base of 10
th
anal-fin ray; pectoral
fins rounded, slightly more elongated in males; pelvic fins short, reaching the first anal fin-
ray in males, reaching the urogenital opening in females, positioned on the outermost
lower bodyline and with minimal interspace, less than 1 mm. in both sexes; caudal
truncated, in males slightly longer than in females; dorsal-fin rays 11, anal-fin rays 16-17,
pelvic-fin rays 8 - 9.; frontal squamation E – type; longitudinal series of scales 39-40, on
caudal 6-7 more scales rows covering approximately 30 % of the caudal-fin length;
transverse series 9-10; number of vertebrae 34; epipleural ribs not bifurcate; sensory
organs, supra-orbital posterior series: 3 neuromast pairs, in 2 V-shaped grooves; 2
sensory organs in mandible series; 1 sensory organ supra-orbital lateral series: in 1
continuous straight grove; Pre-orbital sensory organs series: no pores but isolated
buttons; Post-orbital sensory organs series: an un-counted series of small buttons.
Table. 4: Morphometric and meristic characters of Rivulus (Cynodonichthys) ribesrubrum
new species.
Holotype Holotype largest smallest
in mm in % SL in % SL in % SL
n=2 n=2
Measurements
Total length 67.6 120.9 70.5 67.6
Standard length 55.9 100 55.9 55.8
Pre-dorsal length 72.6 75.4 72.6
Pre-anal length 60.7 63.2 60.7
Length of dorsal-fin base 13.1 13.4 13.1
Length of anal-fin base 22.4 22.4 21.3
Pelvic-fin length 9.9 11.3 9.9
Body depth at anus level 20.6 24.5 20.6
Caudal- peduncle depth 14.3 15.8 14.3
Head length 25.1 28.6 25.1
Counts
Dorsal-fin rays 11 11 11
Anal-fin rays 17 17 16
Pelvic-fin rays 9 9 8
Dorsal to Anal position 10 10 9
Scales
Scales in longitudinal series 41 41 39
scales on caudal fin base 7 7 6
Scales in transversal series 10 10 10
Colors in life: Male. Dorsal side of the body dark grey-brown, iridescent blue laterally, pale
purple to whitish ventrally, red dots laterally spread out over the body not forming
continued lines, dorsal portion of head and lower jaw dark brown; post orbital region with
bluish hue on yellow basis; chin bluish-grey; eye iris brown- golden; dorsal fin hyaline
yellow with sub marginal red border and dark margin, the center towards the base show
numerous spots in signal red color; anal at the base bright blue with a shine of purple and
show in that part numerous signal red spots; the middle section of the anal is green
without markings followed by a narrow sub marginal red band and at the outer edge a fine
black margin; caudal in center hyaline green - yellow showing fine iridescent green
speckles and fine brown dots from hypural plate towards the center, dorsal- and ventral
border of the caudal show a thin orange margin and anterior border has a broad orange
band; pectorals hyaline with orange translucent color at the base; pelvic fins blue with red
margins. No Rivulus spot in any stage of life.
Female. Dorsal side of the body yellowish brown, depending on mood with, or without, a
series of darker scales forming an irregular longitudinal line, sides pale grey ventrally
more pale, sides with irregular series of dots similar as in males but yellow (v.s. signal-red
in males); dorsal portion of head and lower jaw brown; opercula with yellow- green center;
chin soft yellow; eye iris brown- golden; dorsal-fin hyaline yellow with faint yellow speckles
more concentrated to the base, no marginal lines; anal-fin hyaline green, blue at the base
with small yellow speckles; caudal hyaline yellowish green, no markings; pectorals
hyaline; pelvic fins hyaline with yellow shine. No Rivulus spot is present in any stage of
life.
Reproduction: The adult female can produce between 10 and 15 eggs daily. Spawning at
top of substratum. Eggs have a moderate to large diameter of 1.6 – 1.9 mm, amber
colored, and chorion without filaments but with clusters of adhesive fibers. Eggs need a
developing time of 20 -24 days.
Distribution and habitat: Known only from the type locality, numbered with field nr. COL
2008-12, a creek under primary forest canopy, clear swift running water, sandy bottom
with rock boulders and shallow shores, weak cascading profile, no aquatic vegetation,
temperature 20 °C. The creek tributes the upper part of Rio La Miel below the hydro
electro power dam that forms the “Embalsa La Miel”. Rio La Miel is a very fast running
and tumbling clear water river in a very narrow riverbed with stone walls rising high up
hanging over on both sides and this river is hard to concur. The species seems to prefer
the mountainous areas seeking a niche for safe location that are difficult to penetrate by
other fish species like predators. The present author searched intensively to Rivulus
boehlkei that is reported further downstream below San Miguel in a creek feeding Rio La
Miel, Caldas Dpt. but was not able to collect this taxon during his visit closest to the exact
given location.
Etymology: The name of the new species is referring to the unique currant- red spotted
markings on body and fins. (from New Latin: ribes) = currant or gooseberry and (from
Latin: rubrum) = red.
Rivulus (Cynodonichthys) xi new species
(Figs. 8-9: Table 5).
Fig. 8 (previous page): Rivulus (Cynodonichthys) xi, male, Playoncito, Santander
Department, Colombia. Paratype.
Fig. 9: Rivulus (Cynodonichthys) xi, female. Playoncito, Santander Department, Colombia.
Holotype.
Holotype: IAvH-P 11258, female, 57.9 mm SL; Playoncito creek, tributary of Betania river,
Magdalena Basin, Santander Dept., Colombia, approx. 40 km north from San Alberto in
direction of El Playon, 7°33’50”N –73°13’90”W, altitude 588 m; collected by F.B.M.
Vermeulen & F.A. Correa-Polo, February 26, 2008.
Paratypes: IAvH-P 11259, 8 specimen 43.6 – 54.9 mm SL, collected with Holotype,
Playoncito creek, tributary of Betania river, Magdalena Basin, Santander Dept.,
Colombia.; approx. 40 km north from San Alberto in direction of El Playon, 7°33’50”N -
73°13’90”W, altitude 588 m; collected by F.B.M. Vermeulen & F.A. Correa-Polo, February
26, 2008.
Paratype: RMNH.PISC.36367, male 50.7 mm. SL; collected with Holotype, Playoncito
creek, tributary of Betania river, Magdalena Basin, Santander Dept., Colombia.; approx.
40 km north from San Alberto in direction of El Playon, 7°33’50”N –73°13’90”W, altitude
588 m; collected by F.B.M. Vermeulen & F.A. Correa-Polo, February 26, 2008.
Diagnosis: Rivulus xi n. sp. is distinguished from all other Central Colombia congeners in
having the combination of following features: higher range LL scales (41-42 vs. 34-36 in
Rivulus pivijay and 39-41 in all others within the central Colombian clade). Rivulus xi has
relative low pre-dorsal length (70.6 – 74.8 vs. 71.5 -77.9) compared to the others taxa
described herein; higher number of anal fin rays (14 - 16 vs. 13-14 in Rivulus pivijay.
Rivulus xi differs by its color pattern that show’s an unique brown-golden XX-pattern on
the flanks in males, subdued in females, not seen in any other of its clade members and
unique in the genus; by bearing a Rivulus spot in males (juvenile and sub-adults only) and
in females in all stages of life, a feature shared only by Rivulus pivijay, females of Rivulus
magdalenae and R. boehlkei and not by any of the others in the R. elegans group and are
also distinguished by the absence of a white- or orange distal band in the caudal of males,
a feature shared by Rivulus pivijay and R. boehlkei only. In general Rivulus xi reaches
larger SL and is more elongated than Rivulus pivijay, based on DNA sequences
genetically its closest relative. Number of vertebrae in Rivulus xi is highest in the group
(36) while R. pivijay has lowest (31); largest specimen of Rivulus xi measured SL 57.9
mm. vs. SL 48.1 mm. in largest R. pivijay measured.
Description: Morphometric and meristic data of the Holotype and Paratypes are presented
in Table 5. Body slender and elongated, greatest body depth well before pelvic-fin
insertion; body slightly compressed more compressed at the caudal peduncle, dorsal
profile somewhat concave, straight on caudal peduncle; ventral profile more convex but
straight at caudal peduncle; snout length equals eye diameter; mouth opening upwards
oriented; dorsal and anal fins all rounded, slightly more pointed in males, all without
filaments; anal- fin embedded somewhat in the lower body line; dorsal-fin origin at vertical
trough base of anal-fin rays 10
th
- 11
th
; pectorals rounded, more elongated in males;
pelvic-fins slightly longer in males, reaching the first to second anal-fin ray, reaching the
urogenital opening in females, positioned on the outermost lower bodyline and with
minimal interspace, less than 1,5 mm. in both sexes; caudal rounded, in males slightly
longer than in females; dorsal-fin rays 8-10, anal-fin rays 14-16, pelvic-fin rays 6 - 7;
frontal squamation E – type; longitudinal series of scales 41 - 42, on caudal 5 – 7 more
rows covering approximately 33 % of the caudal length; transverse series 9-10. Number
of vertebrae 36; epipleural ribs not bifurcated; sensory organs, supra-orbital posterior
series: 3 neuromast pairs, in 2 V-shaped grooves; 2 sensory organs in mandible series; 2
sensory organs, supra-orbital lateral series: in 2 continuous straight grooves; Pre-orbital
(lacrimal) sensory organs series: no pores but isolated buttons; Post-orbital sensory
organs series: an un-counted series of small buttons.
Colors in life: Male. Dorsal side of the body dark brown, green-golden laterally, bluish
ventrally, orange blotches posterior to the gill-cover forming a broken line that fades out
more posterior into an irregular line of x-shaped orange-brown colored markings, more
ventrally, also posterior to gill-cover, orange colored scales form X-shaped markings
becoming more intense towards the caudal peduncle region; on ventral portion scales
Table 5: Morphometric and meristic characters of Rivulus (Cynodonichthys) xi new
species.
Holotype Holotype largest smallest average
in mm in % SL in % SL in % SL in % SL
n=10 n=10 n=10
Measurements
Total length (mm) 69.7 120.3 69.7 52.9 60.5
Standard length (mm) 57.9 100.0 57.9 43.6 49.7
Pre-dorsal length 71.5 74.8 70.6 73.0
Pre-anal length 58.4 62.7 58.3 60.8
Length of dorsal-fin base 13.3 13.3 9.7 11.2
Length of anal-fin base 20.0 22.7 18.6 20.6
Pelvic-fin length 9.3 10.8 8.8 9.9
Body depth at anus level 19.3 20.9 17.4 19.7
Caudal-peduncle depth 13.5 14.1 12.2 13.5
Head length 23.3 28.8 23.3 25.9
Counts
Dorsal-fin rays 8 10 8 9.0
Anal-fin rays 15 16 14 15.0
Pelvic-fin rays 7 7 6 0.0
Dorsal to Anal position 9 11 9 9.8
Scales
Scales in longitudinal series 42 42 41 40.5
Scales on caudal fin base 7 7 5 5.8
Scales in transversal series 10 10 9 9.4
have pale red and blue colors without clear markings; dorsal portion of head and lower
jaw dark brown; post orbital region golden; opercula with blue blotch anterior to the
pectoral-fin insertion; chin bluish-grey; eye iris orange; dorsal-fin golden, slightly hyaline
with reddish brown markings at the base forming faint lines, more distal with speckles of
the same color; no marginal lines; anal-fin blue at the basal portion with red elongated
vertical markings, green at the central portion with red-brown dots not forming lines, a
marginal band of faint dark aubergine pigment is present; caudal-fin golden, to the outer
margin hyaline, near base with reddish brown dots, pectorals hyaline yellow; pelvic-fins
hyaline, blue at the base, more green at the distal part, with an aubergine margin at the
tip.
Female: Side of body grey to light brown, scales with dark-brown to red edges forming
irregularly fine X- shaped markings at the posterior section, more anteriorly 5 - 6 sets of
scales, reddish brown colored, forming oblique lines that reach the dorsal region and
postorbital region on the head; dorsum, head and lower jaw dark brown; on ventral portion
scales have pale red and blue colors without clear markings; chin bluish grey to white, mid
portion opercula golden with green blotch anterior to pectoral-fin insertion; eye iris orange;
dorsal-fin hyaline whitish with faint brown speckles, no marginal lines; anal-fin as in males
but more subdued, blue at the basal portion with red elongated vertical markings,
greenish in the central part with red-brown dots not forming lines, weak marginal border;
caudal hyaline with yellowish shine at upper- and lower borders near the peduncle and a
large number of brown speckles, larger at the center, smaller towards the margins; a dark
circular Rivulus spot is situated at the dorsal side on the caudal peduncle near the base of
the caudal-fin and is surrounded completely by a whitish border; pectorals hyaline yellow;
pelvic-fins hyaline with bluish shine, no marginal borders.
Reproduction: The adult female can produce between 8 and 10 eggs daily. Spawning at
top of substratum. Eggs have a moderate to large diameter of 2.14 – 2.17 mm, chorion of
eggs without filaments but with clusters of adhesive fibers. Ready to hatch in 16 – 17
days.
Distribution and habitat: Known only from the type locality, a mountain creek at 588
meters altitude under primary forest canopy, clear medium-fast running water, stony
cascading profile, no aquatic vegetation, temperature 24 °C at 18.55 hours, pH 5.8
Etymology: The Greek “xi” denotes the 14
th
letter of the alphabet. The new species is
named Rivulus xi alluding to the unique x-markings on the sides of the male. The species
was distributed among hobbyists under the field code: COL 2008-23, Rivulus species
“Santander”.
Fig. 10: Distribution map showing the species names and locations of members within the
Rivulus (Cynodonichthys) elegans group of Central Colombia and connecting Panama.
DISCUSSION.
Most species of the Rivulus elegans species group have their geographic distribution
between the mountain ranges of the western and eastern Andes in Central Colombia up
to altitudes of 1300 meters above sea level and the connecting southern part of Panama.
The new taxon Rivulus xi occurs at heights of 550 to 600 meters in mountain creeks
feeding the Magdalena Basin while Rivulus pivijay occurs at almost sea level in swamps
near the delta of the Magdalena River. Most taxa occur along the outermost edges of tiny
swift mountain creeks that are tributaries to the Magdalena and Cauca rivers, both
belonging to the Magdalena Basin. Other taxa like Rivulus pacificus Huber 1992 are
reported from Rio Condoto, Atrato River Basin, Choco Dpt., Pacific coast and Rivulus
leucurus Fowler 1944 from Rio Juradó, along the Colombian Pacific coast near the border
with Panama. Both species are thought to be members of the Rivulus elegans group, but
are only known from museum material in poor condition.(Huber 1992) To explain the
presence of the two species R. pacificus and R. leucurus on the Pacific coast west from
the western Corderilla and R. chucunaque on the connecting Panama Isthmus it is
necessary to understand the complexity of the geological history of the area. As early as
the Late Paleocene (50–60 Ma), the Andean orogeny was initiated with major uplift
coinciding with increased volcanism along the eastern arc of the subduction zone. In the
north, the Andes are made up of three relatively distinct and parallel cordilleras, each the
result of different geological processes occurring at different times. The Western
Cordillera is an accreted arc formed in the early Paleocene by compressional deformation
caused by collision of western volcanic arcs with the continental margin. In the north-
western margin this was caused by the subduction of the Nazca Plate. Collision of the
Panama-Choco island arc with the northwestern margin of the South American plate from
12 to 6 Ma was primarily responsible for the uplift of the Eastern Cordillera (Duque-Caro
1990). The narrow Cauca-Patia graben separates the Western and Central cordilleras,
while the broader and elongate Magdalena Valley separates the Central and Eastern
cordilleras. Most taxa within the R. elegans group, including the 4 new species described
herein, have their distribution in tributaries of the Cauca – Magdalena basin. Alternating
episodes of uplift and erosion continued through the Cenozoic, with approximately one-
third of the present elevation in the central Andes achieved by 20 Ma and no more than
half of the present elevation achieved by 10 Ma (Gregory-Wodzicki 2000). Therefore,
much of the Andes in the central and northern regions is very young, and modern
elevation was achieved no earlier than 2.7 Ma. The Choco Block likely originated far from
South America, at least as far as northern Central American latitudes, previous to its
accretion onto the northwestern flanks of the Cordillera Occidental. Where its components
originally formed and how they were amalgamated however, are questions difficult to
answer at present.
The subduction of the Caribbean plate underneath the South American plate produced
the uplifting of the central Cordillera of Colombia, while volcanic islands began to appear
in the region now occupied by the Isthmus of Panama. A widespread extensive lowland
fish fauna, most likely including members of the R. elegans group, was in place before
this vicariant event. The last great and extensive marine incursion event in northern South
America is dated at around 15–10 Ma as sea level rose between 30 and 60 meters above
level at present. Regardless of the exact level of the rise, marine transgressions would
have caused the retraction and partial extinction of the lowland fish faunas in many parts
of northern South America. During periods of low sea level however fish species from the
lowlands could benefit from a wider lowland with freshwater habitats along the coast and
migration became possible towards the Panama Isthmus and towards the Choco block at
the Pacific side of the western Corderilla. This could be an explanation of their presence
in southern Panama and the Choco Dpt.
Although the Rio Cauca is a tributary of the Rio Magdalena and consequently is included
within the latter basin in most classifications, it is also regarded as a separate and distinct
biogeographic unit because the two hydro sheds are indeed distinct at higher elevations
and in their headwater regions, separated by the Cordillera Central. This could explain the
differences found in species within the R. elegans group of the Cauca – Magdalena basin
at present time.
The author did visit the type locality of Rivulus boehlkei during his expeditions but was not
able to collect the species. The new Rivulus ribesrubrum was discovered not far from the
original type locality of R. boehlkei in a small creek, tributary at the right bank of the steep
upper Rio La Miel about 27 kilometer upstream from the town of San Miguel and about 7
kilometer below the hydroelectric power dam that forms the Embalsa La Miel while R.
boehlkei was reported from a temporary brook, tributary to Rio La Miel, Magdalena Basin,
Caldas Prov., Central Colombia, between 5.3 & 12 kilometer downstream from San
Miguel village near the point where the Rio La Miel joins the Rio Cauca. I did try to find
this brook and Rivulus boehlkei following the detailed info on the locality but was not able
to relocate the place. R. ribesrubrum does not show an ocellus in either sex in any stage
of life; has a short snout and a vertical border on the distal margin caudal fin in males. A
barred pattern laterally, a more ventrally oriented position of the mouth, a prominent
supracaudal ocellus in females and fainter in males are reported for R. boehlkei (Huber
1992), and do not match with data found in R. ribesrubrum. The characters mentioned for
R. boehlkei need further study to clarify the phylogenetic position of this species and new
specimens including observations of live fishes are needed to achieve this study. Because
of the harsh accessibility of the Andes and still unstable political situation in the area the
complete geographical ranges of the new taxa are not known. New surveys and extensive
collecting are needed to get a better picture of their geographic spreading and limits.
Reports of Rivulus elegans and Rivulus magdalenae from Villavicencio, a town east of the
eastern Cordillera located in the Orinoco River Basin of the Colombian Llanos are
probably incorrect. This town is a major player in fish exports worldwide, with commercial
companies that may have collected fishes from the Magdalena Basin, and then
erroneously list Villavicencio as the original source. The west flank of the eastern
Corderilla is therefore most likely the outermost boundary where members of the Rivulus
elegans species group have their geological occurrence but future sampling is needed to
confirm this theory.
ACKNOWLEDGEMENTS.
The author likes to express his thanks to Francisco Correa Polo, Santa Marta, Colombia
for his extensive work in the field and his mother Dinorah E. Polo-Alcalá for her hospitality.
To Professor Eberhard Wedler, Santa Marta, Colombia for his hospitality, advice and help
in the field. To professor J. Mol, Surinam, to professor Don Taphorn and professor Bruce
Turner, USA and Dr. Isaäc Isbrücker, The Netherlands for advice and help with this
manuscript. To Dr. A. Aarn, Australia, for corrections in the manuscript. To Dr. R.W. van
den Bos and S.C. Lesire-Rigot, Aruba, for providing radiographs of all taxa. To the Von
Humboldt Institute, Bogota, Colombia and Naturalis, Leiden, The Netherlands for the
proper storage of the type series. The paper benefited from the comments and criticisms
provided by anonymous referees.
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Manuscript submitted on September 8. 2013.
