Until dirt do us apart: On the unremarkable palp morphology of the spider Sternospina concretipalpis Schmidt & Krause, 1993, with comments on the genus Prionolaema Simon, 1894 (Araneae, Tetragnathidae)
Author
Dimitrov, Dimitar
Author
Álvarez-Padilla, Fernando
Author
Hormiga, Gustavo
text
Zootaxa
2008
1698
49
56
journal article
10.5281/zenodo.180745
66f073b9-f692-4384-8998-ac652d284c81
1175-5326
180745
Tylorida striata
(Thorell, 1877)
(
Fig. 1
A–D)
Meta striata
Thorell, 1877b: 427
Meta striata
Hasselt, 1882: 25
.
Argyroepeira bigibba
Thorell, 1887: 140
.
Argyroepeira
s.
Thorell, 1887: 142.
T. striata
Simon, 1894a
: 737
, f. 809.
Argyroepeira
s.
Workman & Workman, 1894: 19, pl. 19.
T. magniventer
Bösenberg & Strand, 1906: 187
, pl. 15, f. 397.
T. striata
Bösenberg & Strand, 1906: 187
, pl. 15, f. 420.
Sternospina concretipalpis
Schmidt and Krause, 1993
: 7
, f. 1.
New synonymy
N.B. See
Platnick (2008)
for complete list of citations.
Types
.
Tylorida striata
: The
location of the Thorell’s
type
is uncertain but most likely it is deposited in the Natural History Museum of the city of Geneva (Levi, unpublished notes) – not examined.
Sternospina concretipalpis
: male
holotype
from the
Comoros
Islands, Grande
Comore
, Boboni,
625 m
,
28.xi.1983
, R. Jocqué (RMCA 160.838, examined).
Justification of the transfer: Detailed study of the
S. concretipalpis
type
shows that this specimen has all diagnostic characteristics of
T. striata
, including the shape of the conductor and embolus, the spermatic duct path, the shape of the paracymbium and the cymbium dorso-basal process (
Fig. 1
A–B). Although we did not examine the
type
of
T. striata
, there are numerous good illustrations of this species available in the literature to facilitate identification (e.g.,
Chrysanthus, 1963
;
1975
; Davies, 1998;
Tanikawa, 2004
). The palpal fusion mentioned by
Schmidt and Krause (1993)
proved to be a misinterpretation, probably as a result of the bad condition of the specimen. The two palps are not fused, but one of them lacks the cymbium together with the tegular and embolic divisions (see below). Based on these observations, we transfer
S. concretipalpis
to
Tylorida
and as a consequence the former genus becomes a junior synonym of
Tylorida
.
Another three species of
Tylorida
have distribution ranges close (or including) the
Comoro Islands
:
T. ventralis
(Thorell, 1877)
,
T. culta
(
O
. P.-Cambridge, 1869) and
T. mornensis
(Benoit, 1978)
. The three of them, however, have very different spermatic duct paths. Additionally,
T. culta
differs in having an elongated and mostly cylindrical abdomen while
T. mornensis
has a distinctive dark marking on the abdomen.
In the original description of
S. concretipalpis
, the authors claim that both palps are fused; if true this would be unique among spiders, as such a remarkable morphological feature has never been described for a spider (or any other arachnid, for that matter). Detailed study of the only available specimen indicates that this statement was a misinterpretation. The right palp of the specimen is broken and is missing all sclerites distal to the tibia (
Fig. 1
C–D). The left palp is slightly damaged (the tegulum is partially broken) but all structures can be observed (
Fig. 1
A–D). Several cotton fibers were holding the remains of the right palp to the cymbium of the left one, thus superficially giving the impression that both are connected, but careful examination of the specimen after removing the cotton fibers demonstrated that the two palps are not more fused together than they are in any other spider species.
The record of
T. striata
on the
Comoro Islands
broadens considerably westwards the known distribution range for this species which is known from
China
to
Australia
. This distribution is quite unusual considering the fact that there are no records of this species from the Indian peninsula. The disjunction may be an artifact resulting from fragmentary knowledge of the real geographic distribution of
T. striata
.