ANARTIA, 25 (2013 “2015”): 64 - 94
ISSN: 1315-642X
Six New Species of Freshwater Crabs
from Pantepui, Venezuela (Crustacea:
Decapoda: Pseudothelphusidae)
Héctor Suárez
Centro de Ecología, Instituto Venezolano de Investigaciones Científicas,
Apartado Postal 21827, Caracas 1020A, Venezuela.
Correo electrónico: hsuarez@ivic.gob.ve
Abstract
Six new species of pseudothelphusid crabs (Crustacea: Deca-
poda: Brachyura)aredescribedfromseveralriversof the Pantepui re-
gion of Venezuela, in the states of Amazonas and Bolívar: Microthel-
phusa aracamuniensis, n. sp., M. guaiquinimaensis, n. sp., M. maiguali-
daensis, n. sp., M. marahuacaensis, n. sp., M. roraimaensis, n. sp., and
Fredius cuaoensis, n. sp.
Keywords: Brachyura, Cerro Guaiquinima, Cerro Marahuaca, Fre-
dius, Microtelphusa, Monte Aracamuni, Serranía de Mai-
gualida, Río Cuao, Roraima.
Seis nuevas especies de cangrejos de agua
dulce del Pantepui, Venezuela (Crustacea:
Decapoda: Pseudothelphusidae)
Resumen
Se describen seis nuevas especies de cangrejos pseudotelfúsidos
(Crustacea: Decapoda: Brachyura) procedentes de varios ríos de la
región pantepuyana de Venezuela, en los estados Amazonas y Bolí-
var: Microthelphusa aracamuniensis, n. sp., M. guaiquinimaensis, n. sp.,
urn:lsid:zoobank.org:pub:5A6BF416-41F9-46AD-88B0-47CBC9674966
M. maigualidaensis,n.sp. M. marahuacaensis,n. sp., M. roraimaensis,n.
sp.,yFredius cuaoensis, n. sp.
Palabras clave: Brachyura, Cerro Guaiquinima, Cerro Marahuaca,
Fredius, Microtelphusa, Monte Aracamuni, Serranía
de Maigualida, Río Cuao, Roraima.
INTRODUCTION
The mountains of the Guiana Shield are located between the
Río Orinoco to the North and the Río Negro to the South, in North
-
ern South America. Its highest prominence is the Pico da Neblina
(3045 m). This group of mountain systems is developed essentially
over two geological substrates: a basement of igneous-metamorphic
rocks (acid granites) and a layer of sedimentary rocks (sandstones)
deposited over that basement (Maguire 1979).
Sandstones, almost entirely belonging to the Roraima Forma-
tion, have suffered important and repeated tectonic and structural
transformations, resulting in fragmented portions of tabular moun-
tains,moreorlessisolatedfromeachother. They have been called Te-
puyes (Tepui, in singular) by local aboriginal people. Tepui summits
usually reach 1500 to 2600 m, but there are a few exceptions where
higher elevations are met (for example Roraima-Kukenán: 2800+ m,
Serranía La Neblina: 3000+ m). Tepuyes emerge abruptly, like
blocks, from lowland to medium elevation hilly areas of savanna and
forest, givingthe local landscape a unique and impressive aspect (Hu
-
ber 1988).
Costa et al. (2014) recorded more than fifty tepuyes in the Gui
-
ana Shield; presenting, for the first time thus, their distribution in a
map with indication of the mountain summits reaching at least 1500
m. This map is coupled with a table presenting, for each tepui, in nu
-
merical figures, the maximum elevation, the area of their summits
and their batters (when known). It is noteworthy that this map shows
only tepuyes above 1500 m, with the exception of Cerro Ichún (430
m), which was included due to its large extension and proximity to
other elevated ranges.
In 1955, Mayr and Phelps, Jr. employed the term “Pantepui” to
define “the sandstone table mountains located in the states of Ama
-
New species of freshwater crabs from Pantepui 65
zonas and Bolívar in Venezuela, and the neighboring areas of Gui
-
ana, Brazil and Colombia”. This definition contains an explicit geo
-
graphical criterion related to the magnitudes of altitude and surface
area of the mountains, as well as an implicit biological criterion, re
-
ferring to the condition of life in those regions (Costa et al. 2014).
Later on, several authors have offered different interpretations
of the term Pantepui, which deviates from the original concept (Mül
-
ler 1973, Hoogmoed 1979, Steyermark 1979, Brown 1987, Neild
1996). In an attempt to give a clearer meaning from the geographical
and biological points of view, Huber (1987) stated that “the “Bioge
-
ographical province of Pantepui, which forms part of the Guyana re
-
gion, is composed by the set of orographic ecosystems developed on
the tabular mountains (tepuyes) of the Roraima Formation of the
Guiana Shield, ranging from 1200-1500 m to 3045 m. It is a tropical
oreobiome in the sense of Walter (1976). The tepuian oreobiome in-
cludes all ecosystems of the superior foothills and summits of the te-
puyes, located in the tropical meso and sub-microthermic altitudinal
levels”.
Nine species of freshwater crabs have hitherto been described
from the rivers of this biogegraphical region (sensu Huber, 1987 and
Costa, [2014]). They belong to the genera Fredius Pretzmann (7 spe-
cies), Microthelphusa Pretzmann (1 species) and Prionothelphusa Ro-
dríguez (1 species) (Rodríguez 1980, Suárez 2006, Cumberlidge
2007). Five new species of Microthelphusa and one new species of Fre-
dius are described in this work, all specimens known of these taxa
werecollected in the mountains of Pantepui, in Venezuela (Plate 1).
A group of Microthelphusa species is distributed from the foot
-
hills of the Andes, along the Cordillera de la Costa (Northern Vene
-
zuela) to the East, until Trinidad: M. barinensis (Rodríguez 1980, M.
forcarti (Pretzmann 1968), M. ginesi Rodríguez and Estevez 1972, M.
odaelkae (Bott 1970), M. racenisi (Rodríguez 1966), M. sucreensis Ro
-
dríguez and Campos 2000, M. turumikiri Rodríguez 1980 and M. vilo
-
riai Suárez 2006. Another group of species is exclusive of the Pante
-
pui province: M. aracamuniensis Suárez, n. sp.; M. bolivari Rodríguez
1980; M. guaiquinimaensis Suárez, n. sp.; M. maigualidaensis Suárez,
n. sp.; M. marahuacaensis Suárez, n. sp.; M. meansi Cumberlidge,
2007; M. rodriguezi (Pretzmann 1968); M. roraimaensis Suárez, n. sp.;
M. somanni (Bott 1967); and M. wymanni
(Rathbun 1905). Apart from
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ANARTIA, 25 (2013 “2015”): 64 - 94
Six new species of freshwater crabs from Pantepui, Venezuela 67
Plate 1. Map of the area of capture localities of the six new species of freshwater crabs described in this paper.
its insular geographical distribution, the genus Microthelphusa exhib
-
its a clear altitudinal preference. Its species are only found above 500
m, and apparently, up to 2000 m (Table 1). The pattern of spatial dis
-
junction is reflected in high levels of endemism. Diagnostic charac
-
ters for the genus are summarized by Suárez (2006).
On the other hand, the genus Fredius, hitherto embraces twelve
known species. Fredius cuaoensis Suárez, n. sp., is certainly the
smallest representative of the genus. It also represents the highest al
-
titudinal distribution for the genus.
METHODS
For the descriptions and comparisons, the author examined un
-
der magnification, samples of preserved biological material col
-
lected years ago by several explorers, which are deposited and cata
-
logued in the Colección de Crustáceos Decápodos “Dr. Gilberto Ro
-
Suárez
68
ANARTIA, 25 (2013 “2015”): 64 - 94
Table 1. Altitudinal distribution of Microthelphusa species.
Species Altitude (meters above sea level)
M. rodriguezi –
M. barinensis 530-570
M. odaelkae 600-800
M. wymani 880
M. roraimaensis 950
M. bolivari 1000
M. meansi 1135
M. guaiquinimaensis 1380-1400
M. aracamuniensis 1000-1500
M. ginesi 1400
M. turumikiri 1500
M. maigualidaensis 1500
M. marahuacaensis 1500
M. viloriai 1500
M. forcarti 1603-1800
M. racenisi 1400-2000
dríguez” (CCDGR-IVIC), of the Instituto Venezolano de Investiga
-
ciones Científicas (IVIC), Caracas-Venezuela.
Description methods followed recommendations of the Fourth
Edition of the International Code of Zoological Nomenclature (ICZN
1999).
Line drawings of morphological structures were produced with
a camera lucida attached to a Stereomicroscope Wild M5. Tridimen
-
sional images of type specimens were produced by digitally adjusting
superimposed photographs (Zerene Stacker® software ) taken with a
camera Canon Eos Rebel T3 on a Leica Reprovit®, with ring flash
lighting.
Abbreviations used are cl: cephalothorax length, cb: cephalo
-
thorax breadth, m: meters above sea level, leg.: legit, fig.: figure, pl.:
plate.
RESULTS
Systematics
Family Pseudothelphusidae Rathbun, 1893
Tribe Kingsleyini Bott, 1970
Genus Microthelphusa Pretzmann, 1968
Microthelphusa aracamuniensis, new species
Figs.1-2, Pl. 1 (distribution), Pl. 2A
Material examined: Cerro Aracamuni, Estado Amazonas, Venezuela, Octo
-
ber 1987, leg. Terramar, 1 male holotype, cl. 17.3 mm, cb. 27.3mm, mature female
paratypes, cl. 17.1 and 15.9 mm, cb. 30.2 and 24.5 mm (CCDGR-IVIC-1088); Cerro
de La Neblina, Departamento Río Negro,Estado Amazonas,Venezuela, 1820-1880
m, leg. W. R. Buck, 7 February 1984, 1 male cl. 19.4 mm, cb. 33.2 mm, 1 mature fe
-
male cl. 21.0 mm, cb. 36.6 mm (CCDGR-IVIC-1090); Cerro de La Neblina, 5°51’N,
65°58’W, Estado Amazonas, Venezuela, 1800 m, leg. P. Spangler and R. A. Faitoute,
3 juvenile male’s cl. 12.5-6.5 mm, cb. 19.8-9.4 mm, 5 juvenile female’s cl.
11.4-5.1mm, cb. 17.9-7.4mm (CCDGR-IVIC-1090).
Diagnosis: Male gonopods with marginal lobe simple, cup
shaped, reaching middle of apical lobe; apical lobe triangular in cau
-
dal view with cephalic border extending farther than caudal one;
field of apical spines very narrow, straight, developed along main
axis of gonopod, with small apical notch; mesial process triangular,
New species of freshwater crabs from Pantepui 69
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with proximal border angled, ending in acute spine directed back
-
wards and slightly upwards.
Description of holotype: Cephalothorax 1.56 times as wide as
long, dorsal surface smooth and polished; cervical grooves shallow
and slightly arquate, not reaching margin of cephalothorax; antero-
New species of freshwater crabs from Pantepui 71
Figure 2. A.- Variation in the shape of thelateral border of cephalothorax of
Microthelphusa aracamuniensis, n. sp.; B.- Third maxilliped of the Holotype;
C.- Left major cheliped of the Holotype.
lateral margins with shallow and long postorbital depression, rest of
border smooth, except for 4-5 obsolescent squamiform papillae set
far apart. Postfrontal lobes low, oblong, inconspicuous; median
groove indistinct over frontal region, deep and wide between post-
frontal lobes. Surface of cephalothorax between post-frontal lobes and
front inclined anteriorly, slightly concave in frontal view. Upper mar
-
gin of front slightly convex in dorsal view, without median notch,
marked with row of minute coalescent papillae; lower margin thin,
slightlysinuousin frontal view, advanced in front of upper margin; sur
-
face of front between upper and lower borders narrower at middle.
Palm of largest chela inflated, with lower margin strongly sinu
-
ous; fingers long, not gaping. Walking legs slender, but not unusually
elongated, largest being those of third pair (total length 1.33 widths
of cephalothorax); merus in this pair 3.8 times longer than wide.
Exopod of third maxilliped 0.38 length of ischium of endognath.
Male gonopods straight in caudal and lateral views. Marginal
lobe simple, cup shaped, reaching middle of apical lobe; apical lobe
triangular in caudal view with cephalic border extending farther than
caudal one; field of apical spines very narrow, straight, developed
along main axis of gonopod, with small apical notch; mesial process
triangular, with proximal border angled, ending in acute spine di-
rected backwards and slightly upwards.
Remarks: This species displays considerable variability in the
morphology of cephalothorax. In the female paratypes cervical
grooves are deeper and straight, the postorbital notch is absent and
the lateral border has 2-3 coalescent papillae before level of cervical
groove, and approximately 10 papillae placed at considerable inter
-
vals from each other behind it; the postfrontal lobes are obsolescent
and the median groove is absent. The specimens from Cerro de La
Neblina have a distinct postorbital notch and 14-16 distinct triangu
-
lar teeth, regularly spaced over the lateral border; the upper border of
the front is well defined, with a row of small but distinct tubercles; in
the largest specimens the median groove between the postfrontal
lobes is distinct throughout, whereas in the juveniles it is absent. The
cephalothorax is relatively narrow in the holotype, while in the fe
-
male paratype and in the male and female from Cerro de La Neblina
it is considerably wider (cb/cl=1.77, 1.71, 1.74, respectively); juve
-
niles have a narrow cephalothorax (cb/cl=1.44-1.50).
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ANARTIA, 25 (2013 “2015”): 64 - 94
Distribution: Only known from the type locality mounts Ara
-
camuni and Cerro de La Neblina, Venezuela, near the Brazilian bor
-
der (1800 – 1880 m) (Pl.1).
Etymology: The specific epithet aracamuniensis refers to the
geographical procedence of the holotype of this new taxon, Cerro
Aracamuni (1400 m) one of the most prominent summits of the Ser
-
ranía La Neblina in the Brazilian-Venezuelan border.
Microthelphusa marahuacaensis, new species
Figs. 3-4, Pl. 1 (distribution), Pl. 2B
Material examined: Cerro Marahuaca, Estado Amazonas, Venezuela, on the
batter of the mountain at 1600 m, leg. E. Osuna, 1 male holotype, cl. 14.8 mm, cb.
24.5mm (CCDGR-IVIC-1109).
Diagnosis: Male gonopods with marginal lobe rounded, cup-
shaped, ending distally in small acute spine; apical lobe with caudal
lamella rounded, shorter than cephalic one, cephalic lamella with
border turned over field of spines, forming elongated flap; field of
apical spines narrow, slit-like, developed along main axis of gono-
pod; mesial process wide, triangular, with proximal border rounded,
ending in acute tip directed backwards and slightly upwards.
Description of holotype: Cephalothorax 1.66 as wide as long,
dorsal surface covered by minute papillae not visible to naked eye; cer-
vical groove straight, deep proximally, and thin, slightly curved dis-
tally, ending near anterior margin of cephalothorax. Anterolateral
margin with notch behind orbit, followed by few crenulations; rest of
margin with approximately 15 sub-equal triangular papillae, except for
last 2-3 that are smaller. Post-frontal lobes low, rounded. Median
groove absents, but cephalothorax depressed in this area. Surface of
cephalothorax in front of postfrontal lobes slightly excavated in frontal
view and inclined anteriorly. Upper border of front slightly convex in
dorsal view, with a row of papillae interrupted at middle, but without
median notch. Lower margin almost straight in frontal view, ad
-
vanced. Surface of front between upper and lower borders low.
Palm of largest chela moderately inflated, with lower margin
sinuous; fingers long, not gaping. Walking legs long and slender, larg
-
est being those of third pair (total length 1.7 width of cephalothorax);
merus in this pair 3.7 times longer than wide; spines of dactylus very
New species of freshwater crabs from Pantepui 73
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small. Exopod of third maxilliped 0.40 length of ischium of endog
-
nath.
Male gonopods short and stocky, with marginal, apical, and
mesial lobes well developed. Marginal lobe rounded, cup-shaped,
ending distally in small acute spine; apical lobe consisting of two dis
-
tinct lamellae, caudal one shorter and rounded, cephalic one with
border turned over field of spines, forming elongated flap; field of
apical spines lodged between two lamellae, narrow, slit-like, devel
-
oped along main axis of gonopod; mesial process wide, triangular,
with proximal border rounded, ending in acute tip directed back
-
wards and slightly upwards.
New species of freshwater crabs from Pantepui 75
Figure 4. A.- Left major cheliped of the Holotype of Microthelphusa ma-
rahuacaensis, n. sp.; B.- Third maxilliped of the Holotype.
Habitat: The holotype was found within the leaves of the bro
-
meliad Brocchinia tatei L.B. Smith, but we cannot ascertain whether
this species lives habitually on this plant.
Remarks: This specie separates from M. aracamuniensis, and
from the rest of the known species of Microthelphusa, because its cau
-
dal plate is pronouncedly shorter than its cephalic, and possesses a
keel striking over its surface; the marginal lobe’s apex ends up in a
thorn in caudal sight. In this species the lateral border of the cephalic
lamella is more broadened than the caudal lamella. This is the only
species of the genus that shows thorns on the distal portion of the fur
-
row of the gonopod. Its cephalic lamella is rounded off.
Distribution: Known exclusively from one individual found on
the summit of Cerro Marahuaca (1600 m) one of the tepuyes of
Amazonas State, Venezuela (Pl. 1).
Etymology: The specific name marahuacaensis alludes to the
type locality of this species.
Microthelphusa guaiquinimaensis, new species
Figs. 5-6, Pl.1 (distribution), Pl. 2C
Material examined: Cerro Guaquinima, Estado Bolívar, Venezuela, 5°50’N,
63°50’W, 1400 m, 30 May 1987, leg. S. Gorzula; 1 male holotype, cl. 16.1 mm, cb.
25.9 mm (CCDGR-IVIC1113). Cerro Guaquinima, Estado Bolívar, Venezuela,
5°58’N, 63°27’W, 1380 m alt., 27 March 1985, leg. F. Barreto, 1 male paratype, cl.
14.2 mm, cb. 22.3 mm (CCDGR-IVIC1114).
Diagnosis: Male gonopods with marginal lobe elongated, cup-
shaped, bent laterally at distal portion. Apical lobe consisting of two
distinct lamellae fused to form rounded process, projected mesially
into small triangular spine, cephalic lamella longer, with border
thickened; field of apical spines narrow, slit-like, developed trans
-
versely to main axis of gonopod. Mesial process wide triangular,
with proximal border rounded, ending in strangled tip directed back
-
wards and slightly upwards.
Description of holotype: Cephalothorax 1.56 times as wide as
long, dorsal surface covered by minute papillae not visible to naked
eye; cervical groove proximally almost straight, deep, continuous
with middle grooves of cephalothorax, becoming obsolescent dis
-
tally. Anterolateral margin with depression behind orbit, followed by
4-5 indistinct papillae; rest of margin with approximately 15 very
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ANARTIA, 25 (2013 “2015”): 64 - 94
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New species of freshwater crabs from Pantepui 77
Figure 5. A.- Total caudal view of the first gonopod of the Holotype of
Microthelphusa guaiquinimaensis, n. sp.; B-E.- Detail of the Holotype first
gonopod in caudal view (B), lateral view (C), cephalic view (D), and mesial
view (E).
small denticles. Postfrontal lobes absent, with eroded depression in
its place. Median groove undefined, but cephalothorax surface exca
-
vated in this area. Surface of cephalothorax in front of postfrontal
lobes depressed at middle; upper margin of front sinuous in dorsal
view, thin, with row of minute papillae, without median notch.
Lower margin sinuous in frontal view, very advanced, surface of
front completely visible in dorsal view of cephalothorax.
Palm of largest chela inflated; fingers short, slightly gaping, sur
-
face polished, with only minute non-colored papillae disposed in
rows. Walking legs slender, but not conspicuously long, largest being
those of third pair (total length 1.27 width of cephalothorax); merus
in this pair 3.4 times longer than wide; spines of dactylus very small.
Exopod of third maxilliped 0.37 length of ischium of endognath.
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ANARTIA, 25 (2013 “2015”): 64 - 94
Figure 6. A.- Right major cheliped of the Holotype of Microthelphusa guai-
quinimaensis, n. sp.; B.- Third maxilliped of the Holotype.
Male gonopods strangled at middle in caudal view, with mar
-
ginal, apical, and mesial lobes well developed. Marginal lobe elon
-
gated, cup-shaped, bent laterally at distal portion; apical lobe consist
-
ing of two distinct lamellae fused to form rounded process, projected
mesially into small triangular spine, cephalic lamella longer, with
border thickened; field of apical spines narrow, slit-like, developed
transversely to main axis of gonopod; mesial process wide triangular,
with proximal border rounded, ending in strangled tip directed back
-
wards and slightly upwards.
Remarks: This species can be separated from other Microthel
-
phusa because its lateral border cephalic lamella contracts exposing
the beginning of the fusion between the lateral lobe and the lateral
border of the cephalic lamella. In lateral sight the lateral threshold is
left over a projection shaped like a spine that separates the apical lobe
from the mesial one.
Distribution: Known to be Cerro Guaiquinima (1400 m) in the
Guiana Shield (Pl. 1).
Etymology: guaiquinimaensis means from Guaiquinima, the
aboriginal local name of the mountain where this species came from.
Microthelphusa maigualidaensis, new species
Figs.7-8, Pl. 1 (distribution), Pl. 2D
Material examined: Serranía de Maigualida, Estado Amazonas, 15 Novem
-
ber 1988, leg. S. Gorzula and G. Medina, 1 male holotype, cl. 17.6 mm, cb. 28.6 mm,
1 male paratype, cl. 16.5 mm, cb. 27.1 mm, 1 mature female paratype, cl. 14.1 mm,
cb. 22.0 mm (CCDGR-IVIC-1108).
Diagnosis: Male gonopods with marginal lobe strongly ribbed,
spatulate, with terminal border rounded and scalloped (crenate),
curved laterally, its base continued laterally by supplementary bul
-
bous projection, with surface deeply wrinkled; apical lobe consisting
of two distinct lamellae fused to form triangular process, with distal
border with strong wrinkles, cephalic lamella longer, with border
thickened and papillated on cephalic side; field of apical spines rela
-
tively wide, open, developed along main axis of gonopod, with in
-
cipient bulge at base; mesial process deep, auriculate, ending in acute
tip directed caudally, with deep furrow (fold) on cephalic side.
Description of holotype: Cephalothorax 1.63 times as wide as
long, dorsal surface smooth and polished, partially covered by
New species of freshwater crabs from Pantepui 79
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minute papillae only visible under magnification; cervical grooves
straight, narrow deep, well defined proximally, becoming obsoles-
cent distally. Anterolateral margin with conspicuous postorbital
notch; 12 flat, rounded papillae behind level cervical grooves, first
five papillae of this series indistinct and placed far apart, becoming
more prominent and closer posteriorly. Postfrontal lobes absent, its
place indicated by faint depressions. Median groove absent, and
cephalothorax surface not excavated in this area. Surface of cephalo
-
thorax in front of postfrontal lobes regularly rounded, not inclined
towards middle; upper margin of front absent, lower margin straight,
partially visible in dorsal view of cephalothorax.
Palm of largest chela inflated; fingers short, thick, leaving small
round gap at internal base when closed, surface of chela polished,
with only minute non-colored papillae disposed in rows. Walking
legs slender, but not conspicuously long, largest being those of third
pair (total length 1.20 width of cephalothorax); merus in this pair 2.8
New species of freshwater crabs from Pantepui 81
Figure 8. A.- Left major cheliped of the Holotype of Microthelphusa maigua-
lidaensis, n. sp.; B.- Third maxilliped of the Holotype.
times longer than wide; spines of dactylus very small. Exopod of
third maxilliped 0.46 length of ischium of endognath.
Male gonopods short and stocky, straight in caudal and lateral
views, with marginal, apical, and mesial lobes well developed; marginal
lobe strongly ribbed, spatulate, with terminal border rounded and scal
-
loped (crenate), curved laterally, its base continued laterally by supple
-
mentary bulbous projection, with surface deeply wrinkled, apical lobe
consisting of two distinct lamellae fused to form triangular process, with
distal border with strong wrinkles, cephalic lamella longer, with border
thickened and papillated on cephalic side; field of apical spines rela
-
tivelywide, open, developed along main axis of gonopod, with incipient
bulge at base; mesial process deep, auriculate, ending in acute tip di
-
rected caudally, with deep furrow (fold) on cephalic side.
Remarks: Of this new group of species, M. maigualidaensis,is
the more physically derived, showing rudimentary reminiscences of
the members of the genus Fredius, as the lateral massive lobe, which
in this taxon appears to be partly product of the fusion of the mar-
ginal lobe with the basal lobe of the field of thorns, it closes the lower
part of the apical lobe in this way, producing a much shorter and ro-
bust appearance. In this species the mesial border of the caudal la-
mella shows transverse keels conferring to it a wrinkled appearance.
A reduction of the latter is appreciated in cephalic sight, giving it
digitiform aspect.
Distribution: Individuals of this species have been found only
in the mountains of the Serranía de Maigualida (Pl. 1).
Etymology: Maigualida is the local name of a remote moun
-
tain range in the border of the Bolivar and Amazonas States in Vene
-
zuela, which form part of the biogeographic Province of Pantepui.
M. maigualidaensis, is named after this mountain range, which is its
type locality.
Microthelphusa roraimaensis, new species
Figs. 9-10, Pl. 1 (distribution), Pl 2E
Material examined: Creek affluent of Kukenan River, at base of Monte Ro
-
raima, Estado Bolívar, Venezuela, 950 m, 6 June 1989, leg. P. Lau, 1 male holotype, cl.
13.5, cb. 21.1 (CCDGR-IVIC-1111). Same data, 31 March 1989, leg. C. Lasso, 1 male
cl. 10.3 mm, cb. 15.3 mm, 1 female, cl. 7.3 mm, cb. 10.4 mm (CCDGR-IVIC-1112).
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New species of freshwater crabs from Pantepui 83
Figure 9. A. Total caudal view of the first gonopod of the Holotype of
Microthelphusa roraimaensis, n. sp.; B-E.- Detail of the Holotype first
gonopod in caudal view (B), lateral view (C), cephalic view (D), and mesial
view (E).
Diagnosis: Male gonopods with marginal lobe spoon-shaped,
curved laterally, with terminal border rounded and fused to lateral
surface; apical lobe consisting of two distinct lamellae fused to form
hooded process, its mesial border folded, caudal lamella longer, end
-
ing in globose projection, cephalic lamella bent cephalically, field of
apical spines relatively wide, open, developed along main axis of
gonopod; mesial process forming bulbous projection on lateral and
cephalic sides, ending mesially in long slender spine directed cau
-
dally.
Description of holotype: Cephalothorax 1.56 times as wide as
long, dorsal surface covered by minute papillae only evident when
magnified; cervical grooves straight, narrow deep, well defined
proximally, becoming shallower distally, ending near margin of
cephalothorax. Anterolateral margin with shallow post-orbital
notch, series of small closely set papiliform teeth evenly distributed
along margin. Post-frontal lobes low, defined anteriorly by wide de-
pressions. Median groove absent and cephalothorax surface not ex-
cavated in this area. Surface of cephalothorax in front of postfrontal
lobes regularly inclined anteriorly, but not towards middle; front in
dorsal view strongly sinuous, upper margin of.front ill defined, with
few papillae, lower margin sinuous, advanced, clearly visible in dor-
sal view of cephalothorax.
Palm of largest chela (right) moderately inflated; fingers long,
slender, gaping, surface of chela polished, with rows of minute coni-
cal hairs implanted in pores. Walking legs slender, but not conspicu
-
ouslylong, largest being those of third pair (total length 1.01 width of
cephalothorax); merus in this pair 2.9 times longer than wide; spines
of dactylus relatively strong. Exopod of third maxilliped 0.20 length
of ischium of endognath.
Male gonopods short and stocky, straight in caudal and lateral
views, with marginal, apical, and mesial lobes well developed; mar
-
ginal lobe spoon-shaped, curved laterally, with terminal border
rounded and fused to lateral surface; apical lobe consisting of two
distinct lamellae fused to form hooded process, its mesial border
folded, caudal lamella longer, ending in globose projection, cephalic
lamella bent cephalically, field of apical spines relatively wide, open,
developed along main axis of gonopod; mesial process forming bul
-
New species of freshwater crabs from Pantepui 85
bous projection on lateral and cephalic sides, ending mesially in long
slender spine directed caudally.
Remarks:AsinM. maigualidaensis, a retraction of the lateral
margin of the cephalic lamella and the basal lobe of the field of
thorns has fused to close the field. The apex of the mesial process has
turned into a thorn; in cephalic sight the apical border of the caudal
lamella projects prominently over cephalic lamella. As viewed from
the same angle, there is an enlargement of the lateral border of ce
-
phalic lamella. Rudiment of the lateral lobe similar to members of
the genus Fredius.
Distribution: this species is so far known from the medium ele
-
vation (950 m) of the Roraima-Kukenan Massif in Venezuela close
to the border with Brazil and Guiana (Pl. 1).
Etymology: The name roraimaensis, of this species of Microthel-
phusa refers to its type locality.
DISCUSSION OF MICROTHELPHUSA
Campos (2001) and Campos and Magalhães (2004) have pos-
tulated that the genus Rodriguezus Campos y Magalhães, represents
a sister-group to all other Kingsleyini. In this genusthe orifice of the
branchial efferent channel is partly closed by a spine of the jugal an-
gle and by the production of the lateral lobe of the epistome, the
merus of the third maxilliped has the endognath regularly curved,
and its exognath is approximately 0.5 times the length of ischium.
As shown by Rodríguez (1986), the adaptation of pseudothelphu
-
sids to air breathing led to a progressive opening of the orifice of the
branchial efferent channel and to an indentation in the border of the
merus; this process is accompanied by a reduction of the exognath
in the third maxilliped. In the species of Microthelphusa dealt with
above, the border of the merus is rounded, as it is in Rodriguezus, but
its exognath is approximately 0.4 times or less the length of the is
-
chium, and the orifice of the branchial efferent channels is open,
thus pointing to a more derived condition. The first male gonopods,
however, retain some of the primitive traits of Rodriguezus,asdis
-
cussed below.
The type of gonopod more closely associated with Rodriguezus
is that of Microthelphusa aracamuniensis, n. sp. Both taxa share simi
-
Suárez
86
ANARTIA, 25 (2013 “2015”): 64 - 94
larities, in the shape of the apex of the marginal lobe, the field of
thorns, and in the shape of the prolongation of the keel of the lateral
border of the cephalic lamella. The latter forms an angular lobe un
-
derneath the apex of the marginal lobe, which should be called basal
lobe of the field of thorns. Microthelphusaaracamuniensis is apparently
the more primitive species in its genus, however, it still shows some
features of Rodriguezus.
Genus Fredius Pretzmann, 1967
The genus FrediusPretzmann, hitherto comprises five species of
large freshwater crabs geographically restricted to the Guiana region
and the Amazon Basin. Rodríguez and Pereira (1992) discussed in
great detail the systematics and distribution of this genus. The new
species described here is smaller than the others previously known.
Fredius cuaoensis, new species
Figs.11-13, Pl. 1 (distribution), Pl. 2F
Material examined: Alto Río Cuao, Estado Amazonas, Venezuela, 5 Octo-
ber 1957, leg. S. Zent, 1 male holotype, cl. 19.9 mm, cb. 30.6 mm (CCDGR-IVIC-
1117).
Diagnosis: Marginal lobe with conspicuous knob-like projec-
tion, continued laterally by subapical bulge; apical lobe subquadrate,
strongly marginated proximally, projected mesial into acute conical
spine directed caudally and distally; field of apical spines narrow, de
-
veloped along main axis of gonopod; mesial process with conical
acute spine directed caudally and distally, with bifid tip; cephalic sur
-
face of this lobe thickened and connected to subapical bulge.
Description of holotype: Cephalothorax 1.54 times as wide as
long, dorsal surface covered by minute papillae not visible unless
magnified; cervical grooves shallow and thin, almost straight, ending
near anterior margin of cephalothorax; anterolateral margins with
shallow postorbital notch, remaining margin with approximately 15
large papillae, coalescent towards beginning of series. Post-frontal
lobes low, small. Median groove absent. Surface of cephalothorax in
front of postfrontal lobes slightly concave in frontal view and in
-
clined anteriorly. Upper border of front slightly convex in dorsal
view; well defined and provided with row of flat papillae, without
New species of freshwater crabs from Pantepui 87
urn:lsid:zoobank.org:act:D53A29E4-422F-4329-83CC-30AA051C9A61
New species of freshwater crabs from Pantepui 89
Figure 12. A.- Fredius cuaoensis, n. sp., detail of the Holotype first gonopod
in mesial view; B.- Apical view of the first gonopod; C.- Third maxilliped of
the Holotype.
Suárez
90 ANARTIA, 25 (2013 “2015”): 64 - 94
Plate 2. Dorsal view of the cephalothorax of six freshwater crab new spe-
cies: A.- Microthelphusa aracamuniensis, n. sp.; B.- M. marahuacaensis, n. sp.;
C.- M. guaiquinimaensis, n. sp.; D.- M. maigualidaensis, n. sp.; E.- M. rorai-
maensis, n. sp.; F.- Fredius cuaoensis, n. sp.
median notch; lower margin thin, slightly sinuous and depressed at
middle in frontal view, advanced; surface of front between upper and
lower borders high.
Palm of largest chela inflated, with lower margin sinuous; fin-
gers short, moderately gaping, mobile finger with scattered black
dots near tip. Exopod of third maxilliped 0.48 length of ischium of
endognath.
Male gonopod short and stocky, straight in caudal and lateral
views. Marginal lobe short, straight, with conspicuous knob-like pro-
jection, continued laterally by subapical bulge; apical lobe subquad-
rate, strongly marginated proximally, projected mesially into acute
conical spine directed caudally and distally; field of apical spines nar
-
row, developed along main axis of gonopod, lodged between two la
-
mellae which constitute apical lobe; cephalic lamella prolonged dis
-
tally and bent cephalically; mesial lobe with conical acute spine di
-
rected caudally and distally, with bifid tip; cephalic surface of this
lobe thickened and connected to sub-apical bulge.
Remarks: The sub-apical bulge present in the first gonopod of
this species is characteristic of the genus Fredius, but other characters,
like the narrow field of spines and the spiniform mesial lobe appear
more typically in Microthelphusa.
Distribution: So far known from the upper Río Cuao in the
State of Amazonas, Venezuela. It might be an endemic to this region.
New species of freshwater crabs from Pantepui 91
Figure 13. Righ major cheliped of Fredius cuaoensis, n. sp.
Etymology: Fredius cuaoensis owns its name to the Amazonian
River Cuao, where the only specimen known was collected by An
-
thropologist Stanford Zent.
ACKNOWLEDGEMENTS
I thank Ángel L. Viloria, for critically reading the first versionof
this article. Two anonymous reviewers effectively corrected my Eng
-
lish grammar and style, and made useful suggestions to improve the
quality of the text. Wilmer Rojas provided technical support in the
elaboration of the plates,and Grisel Velásquez elaborated the map of
the locations of capture of the taxa herein described. I thank the edi
-
tors of Anartia for efficiently dealing with the reviewing and editing
of my notes.
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