Papuan frogs of the genus Cophixalus (Anura: Microhylidae): new synonyms, new species, and a dichotomous key
Author
Kraus, Fred
text
Zootaxa
2012
3559
1
36
journal article
10.5281/zenodo.282919
09d06f43-47e0-4f67-8ed9-54c16248c2c4
1175-5326
282919
Cophixalus ateles
(Boulenger, 1898)
Boulenger (1898) described
Cophixalus ateles
on the basis of several specimens obtained from Moroka, a region in Central Province,
Papua New Guinea
, that is approximately
20–30 km
E of Port Moresby in the foothills of the Owen Stanley Mts. These specimens reside in the British Museum of Natural History in London and the Museo Civico di Storia Naturale Giacomo Doria in Genoa. The most distinctive feature of this species was its very short first finger without a dilated disc, a feature that has proven diagnostic for several other
Cophixalus
species described since that time (
Zweifel, 1956a
,
1980
;
Kraus and Allison, 2000
,
2009
;
Günther, 2006
). However, since Boulenger’s description,
C. ateles
has remained poorly known. The name had been applied to animals from the Central Highlands (
Zweifel, 1956b
;
Tyler, 1963 a
,
b
) that are now referred to
C. shellyi
Zweifel, 1956a
. From those mid-Twentieth-Century publications it appeared that
C. ateles
and
C. shellyi
were similar species: “It is not certain that the apparently diagnostic characters of
C. shellyi
will continue to appear so when more specimens of
shellyi
and
ateles
become available...” (
Zweifel, 1956a
), and “It does appear that
shellyi
is even closer to
ateles
than originally suspected, but until additional topotypic material of the latter is obtained, the specific status of
shellyi
must remain suspect...” (
Tyler, 1963b
). This assumption of close relationship was based primarily on the shared character of a reduced first finger, but both
Zweifel (1956a)
and
Tyler (1963b)
noted that Boulenger’s (1898) illustration of the hand of
C. ateles
did not agree well with available specimens. Those discrepancies, the faded color patterns and soft state of preservation of the
type
series (
Tyler,1963b
), and the lack of additional topotypic material of
C. ateles
have made exact identity of that species uncertain to the present.
More recently,
Kraus and Allison (2006)
named three new species of closely related
Cophixalus
that occur in the Papuan Peninsula of New
Guinea
. Of these,
C. sisyphus
was diagnosed by its small size (SV =
12–14.1 mm
), tuberculate dorsum, reduced first finger with a poorly developed disc lacking a circum-marginal groove, variegated or striped dorsal pattern, and a variety of morphometric details distinguishing it from its close relatives
C. variabilis
and
C. timidus
, also named in that same paper. Directly relevant to the present discussion is that
Kraus and Allison (2006)
distinguished
C. sisyphus
from
C. ateles
by the tuberculate dorsum and variegated or striped dorsal pattern of the former. This determination was based on photographs of two
paralectotypes
in the British Museum, which were very faded, as noted earlier (
Tyler, 1963b
), and showed no evidence of dorsal tuberculation.
Since the description of
Cophixalus sisyphus
two additional specimens of that species (BPBM 27492, 27494) have become available from near Moroka, Central Province,
PNG
, the
type
locality of
C. ateles
. This unexpected discovery, and recent opportunities to directly compare
paratypes
of
C. sisyphus
(BPBM 19304–05, 19314) to the
lectotype
(MSNG 29116) and seven
paralectotypes
of
C. ateles
(MSNG 50182 [
5 specimens
under same number], BMNH 1947.2.12.6–7) allowed me to determine whether the presumptive diagnostic features of
C. sisyphus
were valid vis-à-vis
C. ateles
. They are not.
FIGURE 1.
Bivariate plot of principal component 1 (eigenvalue = 0.125) versus principal component 2 (eigenvalue = 0.025) for two paralectotypes of
Cophixalus ateles
(filled diamonds), 24 types of
C. sisyphus
(triangles), one recent specimen of
C. sisyphus
from the type locality for
C. ateles
(open diamond), 14 types of
C. timidus
(squares), and 49 types of
C. variabilis
(circles) showing no morphometric discrimination between
C. ateles
and
C. sisyphus
. Component loadings presented in Table 1. All specimens are male.
When compared side by side, there is no morphological feature to distinguish the
types
of the two species. Further, except for the smooth skin and some rather shrunken measurements of some of the
types
of
C. ateles
, there is no obvious difference in shape of body proportions to distinguish them from the
paratypes
of
C. sisyphus
. This is confirmed by principal components analysis of these specimens vs.
type
specimens of the closely related
C. sisyphus
,
C. timidus
, and
C. variabilis
. In both bivariate (
Fig. 1
) and 3-dimensional (not shown) plots of wellpreserved specimens, the two specimens of
C. ateles
cluster with the
type
series of
C. sisyphus
to the exclusion of the similar
C. timidus
and
C. variabilis
. The specimens of
C. ateles
are, indeed, at one extreme of the distribution of
C. sisyphus
along PC1. This axis largely reflects specimen size, judging by the uniformly positive loadings of the constituent variables (
Table 1
). The position of the
C. ateles
specimens at the low end of PC1 seems to be a reflection of their smaller measurements for a number of features relative to their overall body size. This apparently reflects measurement error—especially with respect to disc width—due to the soft and somewhat shrunken state of preservation of these specimens. When disc widths for these two specimens are artificially increased to be in line with those obtained from the recent
C. sisyphus
types
of those body sizes, both
C. ateles
types
more closely approach the distribution of the
C. sisyphus
types
, with the
C. ateles
specimen lower on the graph now lying in the midst of adjacent
C. sisyphus
specimens (graph not shown). Thus the little difference that appears between the
C. ateles
types
and
C. sisyphus
types
in multivariate analysis seems to merely reflect differences in preservation quality.
TABLE 1.
Loadings for log-transformed characters used in principal components analysis of covariance matrix for adult males of
Cophixalus ateles
,
C. sisyphus
,
C. timidus
, and
C. variabilis
. Included specimens are listed in the Appendix.
| PC1 |
PC2 |
PC3 |
| Eigenvalue |
0.12466 |
0.02471 |
0.01154 |
| Cumulative percent variation |
0.678 |
0.812 |
0.875 |
| Variable |
| logSV |
0.269 |
0.087 |
0.202 |
| logTL |
0.361 |
0.011 |
0.292 |
| logEN |
0.248 |
0.097 |
0.081 |
| logIN |
0.125 |
0.008 |
-0.031 |
| logSN |
0.228 |
0.079 |
0.042 |
| logTY |
0.267 |
-0.951 |
-0.115 |
| logEY |
0.208 |
0.064 |
0.258 |
| logHW |
0.240 |
0.017 |
0.149 |
| logHL |
0.240 |
0.014 |
0.194 |
| logHandL |
0.397 |
0.109 |
0.227 |
| log3rdF |
0.469 |
0.172 |
-0.455 |
| log4thT |
0.246 |
0.160 |
-0.683 |
Color pattern for several of the
type
specimens is faded, but others show the dorsal and ventral pattern elements typical of
C. sisyphus
, including dark dorsal blotches and supratympanic line (two specimens), a broad mid-dorsal pale stripe margined in black (one specimen), dark punctations on the chin and chest (six specimens), and paired pale pectoral spots (two specimens). Furthermore, in basing their diagnosis of
C. sisyphus
vis-à-vis
C. ateles
on the smooth skin and lack of color pattern in the latter,
Kraus and Allison (2006)
overlooked the fact that Boulenger (1898) mentioned that
C. ateles
had small warts and some pattern elements, although the latter were not specified in detail beyond noting the occasional presence of black dorsolateral lines and a light vertebral stripe. The frequent hourglass pattern seen on the dorsum and the dark flecking and blotching often seen in
C. sisyphus
(
Kraus and Allison, 2006
)
were not mentioned by Boulenger, although the black dorsolateral lines he did mention presumably represent the lateral margins of the hourglass markings described for
C. sisyphus
. Given the lack of structural differences between
C. ateles
and
C. sisyphus
and the fact that the few color-pattern details given by Boulenger for
C. ateles
are consistent with some of the patterns seen in
C. sisyphus
, I synonymize
C. sisyphus
with
C. ateles
. The taxonomic history of
C. ateles
becomes: