A new species of the genus Alsodes (Anura: Neobatrachia) from the Nothofagus forest, Coastal Range, Southern Chile, identified by its karyotype
Author
Cuevas, César C.
text
Zootaxa
2008
1771
43
53
journal article
10.5281/zenodo.182136
89f06dbf-d0eb-4d31-a9ec-78df82bd6676
1175-5326
182136
Alsodes norae
sp. nov.
(figs. 2, 3)
Holotype
.
IZUA
3541, an adult male with well developed sexual secondary attributes collected by César Cuevas, Javiera Cuevas, and Ignacio Cuevas, on
12 May 2006
; Parque Oncol (
39º41’S
,
73º18’W
;
720 m
elevation;
29 km
NW, 35 minutes by road from Valdivia city), Valdivia Province, Western slopes of the Coastal range (fig. 1).
Paratypes
.
IZUA
3534-3535: two males,
IZUA
3536, 3540; two females, and
IZUA
3537 – 3539; three juveniles, collected on
5 may 2003
by César Cuevas and Javiera Cuevas at the
type
locality. Same data as
holotype
.
Diagnosis.
Alsodes norae
sp. nov.
can be distinguished from its congeners by the following combination of characters: 1) maximum snout-vent length in males (SVL) 61.4 mm, 2) spine of contrasting vivid, yellow and black colours, 3) head with yellowish triangle between anterior border of the eyes and the snout tip, 4) snout slightly truncated in dorsal and lateral profile, 5) iris brilliant bronze-yellowish, 6) postocular fold well developed extending beyond of the insertions of arms, 7) flanks very granular, 8) Inner palmar tubercle oval and enlarged, bigger than the outer, 9) carpal elements of hands cartilaginous, 10) dorsum of legs with thin dark transversal bars, 11) toes thin, long and strongly fringed, 12) 2n = 30 (22 biarmed and 8 uniarmed chromosomes), FN = 52, 13) NOR on pair 4.
Comparison:
Alsodes norae
can be distinguished from
A. valdiviensis
because the new species present the carpal elements cartilaginous (ossified in
A
.
valdiviensis
). The new species differs of
A. barrioi
because this species possesses a strongly truncated snout, and little developed palmar, metatarsal and subarticular tubercles. It differs from
A. vanzolinii
, because this species has the loreal region flat (concave in
A. norae
), and the postocular fold reaching only the insertion of arms (beyond in
A. norae
). It differs from
A. nodosus
by the form of nuptial bilateral patches on the chest. In
A. nodosus
these are formed by eight to nine little rounded patches composed of tiny thorns (a big one in
A. norae
). From the chromosome perspective,
Alsodes norae
can be easily distinguished from the other
Alsodes
species from the Coastal Range;
A. valdiviensis
,
A. barrioi
,
A. vanzolinii
,
and
A. nodosus
,
because these species have 2n = 26; NF = 52, 2n = 34; NF = 52, 2n = 26; NF = 50, and 2n = 22; NF = 44 respectively. Moreover,
A. norae
has four uniarmed pairs (fig. 4), contrasting with
A. barrioi
(eight),
A. vanzolinii
(one) and
A
.
valdiviensis
(fig. 6A, all biarmed pairs). When C-banding patterns of
Alsodes norae
are compared with those of other species, the five species located in the Coastal Range display autoapomorphic patterns of C- bands (fig. 5). Finally,
A. norae
is restricted to a very small area and has not been encountered in sympatry with any of the other congeneric species (see fig. 1).
FIGURE 2.
Holotype of
Alsodes norae
(A) Lateral view, (B) dorsal view. Bar equal 1 cm.
TABLE 1.
Measurements (mm) of the type series, adults and juveniles of
Alsodes norae
sp. nov.
Character abreviations are: SVL, snout vent length; HL, head length; HW, head width; ED, eye distance; IDi, internarial distance; ThL, thigh length; TL, tibia length; FL, Foot length. * Cleared and stained.
| Characters Holotype |
Paratype |
Paratype |
Paratype |
Paratype |
Paratype |
Paratype Paratype |
| IZUA 3541 |
IZUA 3534 |
IZUA 3535 |
IZUA 3536 |
IZUA 3537 |
IZUA 3538 |
IZUA 3539 IZUA 3540 |
| male |
male |
male |
female |
female |
juvenile |
juvenile female * |
| SVL 61.4 |
48.1 |
36.2 |
35.8 |
30.6 |
29.9 |
28.9 46.0 |
| HL 23.2 |
18.0 |
13.2 |
13.0 |
12.8 |
10.2 |
10.5 17.7 |
| HW 24.0 |
20.3 |
14.4 |
13.5 |
12.7 |
11.8 |
11.9 17.3 |
| ED 8.9 |
5.2 |
4.4 |
4.9 |
3.8 |
3.5 |
3.9 5.3 |
| IDi 5.6 |
4.6 |
3.7 |
3.4 |
3.5 |
3.3 |
3.4 5.0 |
| ThL 32.1 |
24.5 |
17.2 |
15.8 |
15.2 |
14.1 |
14.0 22. 8 |
| TL 31.9 |
26.6 |
16.4 |
15.9 |
14.8 |
13.4 |
12.4 22.6 |
| FL 51.3 |
43.7 |
24.9 |
24.4 |
22.0 |
20.9 |
20.8 34.2 |
Description of the
Holotype
.
A male with body robust, arms and legs well developed. SVL 61.4 mm. Head depressed 1.1 times wider than long. Snout slightly truncated in dorsal and lateral profiles (fig. 2 A, B).
Canthus rostralis
well developed slightly curved. Loreal region slightly concave in cross section and skin smooth. Nostrils located anterolaterally, nearest to the tip of the snout than anterior border of the eyes. Eye diameter near 1:1 the eye-nostril distance. Interorbital distance 1.6 times internarial distance. Tympanum absent, postocular fold well developed extending beyond the insertion of arms. Tongue rounded, with a notch at the tip. Choanae rounded; dentigerous processes (4 - 5) of vomer between the choanae. Forelimbs of male not hypertrophied. Fingers long with white rounded tips, in order of increasing length: I = II – III – IV. Webbing on hand absent. Palmar tubercles well developed; the inner bigger than the outer which is divided in two (fig. 3A). Male with dorsal surface of first and second finger with thorny excrescences (fig. 3B).
Hind
limbs normally developed. Tibiotarsal joint reaches the anterior border of the eye. Toes long, thin, with white rounded tips and strongly fringed, in order of increasing lengths: I – II – III – V – IV (fig. 3C). Inner metatarsal tubercle oval and prominent. Tarsal fold well developed, covering ¾ of the tarsus. Flanks very granular; dorsal surface of body moderate in rough aspect. Arms, legs and ventral surface of body smooth. Skin around vent and posterior thighs grainy. Chest of male with two clearly delimited bilateral rounded patches (fig. 3D). Measurements of the
type
series are shown in the
Table 1
.
TABLE 2.
Relative length, arm ratio (mean and standard deviation), and types of chromosomes of
Alsodes norae
sp. nov.
| Chromosomes |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
14 |
15 |
| RL a 111.94 |
101.13 |
92.83 |
88.67 |
80.12 |
71.82 |
69.93 |
62.11 |
59.43 |
54.38 |
48.77 |
46.34 |
39.76 |
39.28 |
32.52 |
| AR b 1.15 |
3.31 |
3.74 |
1.62 |
3.12 |
∞ |
1.88 |
∞ |
1.97 |
1.30 |
∞ |
∞ |
1.38 |
1.39 |
1.29 |
| CC c M |
ST |
ST |
M* |
ST |
T |
SM |
T |
SM |
M |
T |
T |
M |
M |
M |
a According to
Bogart 1970
, b long arm / short arm, and c 1.0 – 1.7 = M = metacentric; 1.8 – 3.0 = SM = submetacentric; 3.1 – 7.0 = st = subtelocentric; 7.1 - ∞ = T = telocentric. * Secondary constriction position.
FIGURE 3.
Morphological details of the male holotype IZUA 3541 of
Alsodes norae
. Left hand (A) palmar attributes, (B) nuptial asperities. Left foot (C) plantar surfaces. Chest (D) ventral view with nuptial pad. Pectoral girdle (E) arciferal. Bars equal 5 mm.
Pectoral girdle.
The
paratype
IZUA 3540 has the pectoral girdle arciferal and the xiphisternum notoriously expanded and deeply notched with a little hole in the centre (fig. 3E).
Colour in life.
Dorsal ground of head, forelimbs, hindlimbs and body of vivid yellow colour with moderately granular appearance. A dark bat figure with spread wings is observed along the dorsum of head ending at the middle of body. Hindlimbs dorsally with thin dark transversal bars. Ventral surface of thighs yellowish in colour in the groin region. Venter light cream with dark reticulations. Upper part of the iris golden yellowish with black reticulations (fig. 2A).
FIGURE 4.
Chromosomes of
Alsodes norae
(A) Standard karyotypes, (B) C-banded karyotype, (C) secondary constriction and (D) nucleolus organizer region position.
Colour in preservative (alcohol 70 %).
The
holotype
(IZUA 3541) has the dorsal ground of head, forelimbs, hind limbs and body slight grey with a dark bat-like figure with spread wings in form, starting from the middle of eyes until the insertion of arms, ending towards the vent as many parallel longitudinal lines in appearance (fig. 2B). Head with a light gray triangle between eyes and the tip of the snout. A dark line extends over postocular fold. Belly, throat, ventral areas of arms and thighs whitish in the
holotype
, but with dark reticulations in the younger specimens.
Variation.
One female (IZUA 3537), a preadult (IZUA 3534) and a juvenile (IZUA 3538) exhibit the same general characteristics of the
holotype
with some minor differences. The dorsum, flanks, and dorsal surfaces of the legs are covered with minute granules. The postocular fold reaches the middle of the body. Measurements of these specimens are shown in
Table 1
.
Chromosomes.
Chromosomal polymorphisms among individuals analyzed were not detected. So, the standard karyotype of
Alsodes norae
sp. nov.
possesses a diploid number of 30 chromosomes (eleven biarmed and four uniarmed pairs) with a fundamental number (FN) 52. A moderate gap size it is discernible between pairs 5 and 6. According to their relative lengths, pairs 1 – 2 are large (> 100 units), 3 – 5 intermediate (80 – 100 units) and 6 – 15 are small (<80 units). By their centromeric ratio (r), pairs 1, 4, 10, 13 – 15 are metacentric (M); 7 and 9 submetacentric (SM); 2, 3 and 5 subtelocentric (ST), and 6, 8, 11 and 12 telocentric (T). A secondary constriction of
type
IV (
King 1980
) was detected on the long arm of pair 4 (M). Karyotype data are shown in
Table 2
.
The C-banded karyotype (fig. 4B) exhibits: centromeric bands on all except pairs 6, 7, 11, 12, and 13; telomeric bands on short arms of pairs 1, 3, and 5; paracentromeric bands on telocentric pairs 8, 10, 11 and 12, and interstitial bands on both short and long arms of pair 1, and in long arms of pairs 5, 7 and 14. Finally, heterochromatic blocks were detected on long arms of pairs 2, 3, and 6. The C-banded ideogram is represented in the figure 5B. Silver staining of chromosomes showed the NORs (with tandem duplication, fig. 4D) to be located within the secondary (nucleolar) constrictions on the short arm of pair 4 (fig. 4C).
Distribution and ecology.
The new species is only known from the
type
locality, Parque Oncol, a small woody area of only 754 ha, recognized as a fragment of the original Valdivian rain forest (
Veblen
et al
. 1980
).
FIGURE 5.
C-bands ideograms of the five
Alsodes
species from the Coastal Range of Chile (A)
A. valdiviensis
, (B)
A. norae
, (C)
A. vanzolinii
, (D)
A. barrioi
, (E)
A. nodosus
.
The tadpole of
A. norae
has yet not been collected. This woody area was characterised by
Oberdorfer (1960)
as dominated principally by
Eucryphia cordifolia
and
Aextoxicum punctatum
and less by
Laureliopsis philippiana
,
a vegetational asociation named as Lapagerio-Aextoxiconetum and Laureliopso-Weimanniatumm Oberd, occurring in a zone of great humidity along the Pacific coast (
Veblen
et al.
1980
). The Valdivian rain forest region generally has a west coast maritime climate [Oceanic Region with Mediterranean influence (zone of oceanic tendency)] (di
Castri 1968
) characterized by an annual average temperature of 10.5 ºC (with a maximum average of 14.2 ºC and a minimum average of 6.9 ºC), relative humidity 84 % and rainfall
2000 - 2500 mm
per year. Specimens of
Alsodes norae
sp. nov.
were frequently found under fallen logs into the humid forest. Other frogs that occur in Parque Oncol are
Batrachyla antartandica
,
Rhinoderma darwinii
,
Eupsophus roseus
and
E. vertebralis
. However, at first sight animals of these species are easily distinguishable in their phenotypic appearance from those of
Alsodes
.
Batrachyla antartandica
,
R. darwinii
and
E. roseus
are smaller sized frogs (
30 mm
to
40 mm
).
Eupsophus vertebralis
also is a large sized frog but it differs from
Alsodes norae
in possessing a white vertebral line and in lacking bilateral nuptial patches in the chest (Formas 1982).
Etymology.
The specific name of the new taxa is the genitive Latin form of Nora, the author`s grandmother, an extraordinary Chilean woman.
FIGURE 6.
Karyotypes with 2n = 26 (A)
Alsodes valdiviensis
with comparative purposes. Reformed from that of (B)
Alsodes norae
(2n = 30), and (C)
A. barrioi
(2n = 34) by means of hypothetic mechanisms of chromosome evolution in some
Alsodes
species. In B and C small numbers beside some chromosomes indicate the original chromosome position procedence.
Discussion.
Although only three adult males (IZUA 3534, 3535, 3541), two females (IZUA 3536, 3537, 3540) and three juveniles (IZUA 3538 - 3539) of
Alsodes norae
were collected in the
type
locality, their generic assignments is justified by the absence of a tympanum in all specimens, added to the male morphologic attributes (thorny excrescences on the thumb and chest, arciferal pectoral girdle) (fig. 3), which are concordant with the generic diagnosis given by
Cei (1980)
and
Formas
et al
. (1998)
. In addition, the skull of
A
.
norae
(here not described) presents a similar cranial pattern as those previously described for
A
.
gargola
,
A
.
vanzolinii
, and
A
.
valdiviensis
(
Lynch 1978
,
Formas and Vera 1982
;
Formas
et al.
2002
).
Formas
et al
. (2002)
described
A. valdiviensis
from Cerro Mirador, Cordillera Pelada (
40º08’S
,
73º40’W
;
1100 m
altitude). This area of the Coastal Range is distant only
60 km
(in a straight line) to the
type
locality of
A. norae
, however, both mountainous formations (Cerro Mirador and Parque Oncol) are separated by the Valdivia river estuary (fig. 1). The specimens of
A. valdiviensis
show morphological and chromosomal differences to those of
A. norae
.
Alsodes valdiviensis
has: opaque colours on the dorsum, unbarred legs, a postocular fold reaching the anterior border of arms, palmar tubercles more reduced in size, general aspect less granulose, prevomers with seven prevomerine teeth (
4-5 in
A. norae
). Its carpal elements are osseous while there are cartilaginous in
A. norae
,
a condition only described before for
Insuetophrynus acarpicus
(Barrio 1970)
, and
Telmatobius chusmisensis
(
Formas et al. 2006
)
. Finally, both species differ in their chromosomic complement (2n=26,
A. valdiviensis
; 2n=30,
A. norae
).
Most of
Alsodes
species have been described based on external adult morphology but some of them only have been recognized as different by displaying autoapomorphic chromosomic characteristic (
Veloso
et al
. 1979
;
1981
;
Cuevas and Formas 2005b
). In this framework, distributional criteria and chromosome evidence (2n = 30; FN = 52,
Fig. 4
,
5
B) are the main arguments that justified the erection of the new taxon herein (
Cuevas and Formas 2005b
). The genesis of 2n =
30 in
A
.
norae
probably involved Robertsonian rearrangements (fissions of biarmed chromosomes) (
Cuevas and Formas 2005b
) which occurred in a hypothetical ancestor with 2n = 26, such as was proposed by
Formas
et al.
(2002)
for
A. barrioi
. This hypothesis can be illustrated by a didactical exercise, i.e., when all telocentric pairs of
A
.
norae
and those of
A. barrioi
are fused by the centromeric region conforming a karyotype with 2n = 26 from each other (fig. 6 B, C). The cases of
A. nodosus
(loss of four small pairs, NF = 44) and
A. vanzolinii
(presence of a telocentric pair, NF = 50), may be explained by translocations and pericentric inversions respectively (
Veloso
et al
. 1979
;
Cuevas and Formas 2003
).
The discordance between chromosome and morphological evolution observed in
Alsodes
(
Cuevas and Formas 2001
)
, agrees with
Lande`s (1979)
hypothesis which claims that chromosome rearrangements do not involve drastic phenotypic changes. Such chromosome mechanisms would occurs in isolated populations (such as members of
Alsodes
underwent along the Coastal Range, fig. 1) involving demographic processes (small population size). This suggests a conserved morphological evolution in
Alsodes
such as has been observed in other amphibians (
Bogart 1991
;
Cherry
et al
. 1978
;
Stuart
et al
. 2006
), as in the case of
Eleutherodactylus
.
When gross chromosome morphology (2n, FN) is analyzed in relation to geographical range,
Alsodes
can be grouped into species with variable karyotypes i.e. 2n = 30, FN = 52 (
A
.
norae
sp. nov.
); 2n = 22, FN = 44 (
A. nodosus
); 2n = 26, FN = 50 (
A. vanzolinii
); 2n = 34, FN = 52 (
A. barrioi
); 2n = 26, FN = 52 (
A
.
valdiviensis
) (fig. 5) (
Veloso
et al
. 1981
; Formas and Vera 1983;
Cuevas and Formas 2003
;
2005b
) distributed along the Coastal Range (32º to 40ºS); and species that share a karyotype with 2n = 26, FN = 52 (
A. australis
,
A. gargola
,
A. hugoi
,
A. igneus
,
A. kaweshkari
,
A. montanus
,
A. pehuenche
,
A. tumultuosus
,
A. verrucosus
) (
Kuramoto 1990
;
Cuevas and Formas 2003
;
2005b
) distributed along the Andes Range (32º to 48ºS). An exception to this rule is
A
.
nodosus
with a range including both the Coastal Range and the Andes (
Bogart 1970
) (fig. 1).
In the last 10 years, eight new Chilean anurans species (14.3% of total current members) have been described [six in
Alsodes
(
Formas
et al
. 1997
;
1998
;
2002
;
Cuevas and Formas 2001
;
2005a
), and two in
Eupsophus
(
Ibarra-Vidal
et al
. 2004
;
Veloso
et al.
2005
)]. These are examples of multiple cases of phenotypically resembling species which imply that amphibian diversity remains significantly underestimated along the Chilean territory. Thus, the outstanding chromosome heterogeneity (fig. 5), and restricted distribution at high altitudes encourage to carry on future analyses of specimens from new places of the Coastal Range (Chiloé Island
42.5ºS
; Osorno Province
40.8ºS
; Cautín Province
39.5ºS
; and Cauquenes Province 36ºS). Such studies would likely result in the discovery of new chromosome numbers, and detect new species in the genus
Alsodes
.
Finally, the recognition of the Coastal Range as an important center of diversification of the Chilean anuran fauna (unknown in all its extension), could constitute a cornerstone to the conservation of this unique geomorphologic and floristic formation.