A new iphiculid crab (Crustacea, Brachyura, Leucosioidea) from the Middle Miocene of Austria, with notes on palaeobiogeography of Iphiculus
Author
Hyžný, Matúš
Author
Gross, Martin
text
Zootaxa
2016
4179
2
263
270
journal article
10.11646/zootaxa.4179.2.6
06e87c9b-0077-437a-b313-4aa8cd55cce3
1175-5326
PMC5321562
27811673
163902
7BEE4FFC-36E8-473D-8D4E-53D151A8CD2F
Iphiculus eliasi
sp. nov.
(
Figs 2
A, 3A–E, 4A–C)
Diagnosis
. Carapace transversely subovate in outline, widest at level of posteriormost anterolateral spine; lateral margins bearing 6 short triangular spines; dorsal carapace surface covered evenly with large rounded tubercles: hepatic region with tubercle, gastric region with 3 pairs of tubercles, branchial region with 3 tubercles.
Etymology.
The species name is dedicated to Eliáš, son of the first author.
Material examined.
Holotype: near-complete carapace UMJGP Inv.No. 75.612, max. length,
15.7 mm
; max. width, 19.0 mm (
Figs 3
A–D). Paratype: near-complete carapace UMJGP Inv.No. 75.613, max. length, 13.0 mm (preserved portion); max. width,
17.2 mm
;
Fig. 3
E). Additional specimen: carapace fragment UMJGP Inv.No. 211339;
Fig. 4
A–C).
FIGURE 3.
Type material of
Iphiculus eliasi
sp. nov.
A–D, holotype UMJGP 75.612 in dorsal (A), posterodorsal (B), frontal (C), and posterior view (D); E, paratype UMJGP 75.613 in dorsal view. Specimens were coated with ammonium chloride prior the photography. All specimens to scale.
Description.
Small carapace; transversely subovate in outline; slightly wider than long, widest at midlength, at level of posteriormost anterolateral spine; dorsal surface moderately convex in both directions. Front not projected, slightly raised, narrow, not well preserved, presumably bilobed. Orbits small, concave, anteriorly directed. Lateral margins bearing 6 short triangular spines, anterolateral margin with 4 spines, posterolateral margin with 2 spines; corners between posterolateral, posterior margins pointed; posterior margin straight, narrow. Dorsal surface of carapace evenly covered with many large, densely packed granules, nearly identical in size (if cuticular surface preserved) or with round concave pustules (if cuticular surface not preserved). Carapace surface covered evenly with large rounded tubercles: hepatic region with 1 tubercle, gastric region with 3 pairs of tubercles, branchial region with 3 tubercles. Carapace grooves absent in anterior carapace portion, well developed in posterior carapace portion. Gastric region large, indistinctly demarcated with grooves. Cardiac region ovate in outline, strongly arched. Branchial regions broad. Intestinal region narrow without large spines. Sternum, pleon, pereiopods unknown.
Occurrence.
The species is known only from its
type
locality at
Wetzelsdorf
(
Austria
).
Remarks
.
Iphiculus eliasi
sp. nov.
is closest to the extant
I. convexus
in terms of the morphology of the dorsal carapace. The latter species, however, has a relatively wider carapace closer to the anterior half and possesses more large round tubercles on the dorsal carapace, especially on the hepatic and gastric regions (
Fig. 2
A
versus
Fig. 2
B). Another extant species,
I. spongiosus
, differs from
I. eliasi
sp. nov.
by the presence of large anterolateral spines and the possession of dorsal carapace tubercles which are more projected outwards (Ng
et al.
2008: fig. 79). Similarly, all fossil species of
Iphiculus
so far known, i.e.
I. granulatus
Morris & Collins, 1991
,
I
.
miriensis
Morris & Collins, 1991
, and
I. sexspinosus
Morris & Collins, 1991
, have well-developed anterolateral spines (
Morris & Collins 1991: figs 15, 14 and 17, respectively
) which are absent in
I. eliasi
sp. nov.
FIGURE 4.
Additional material of
Iphiculus eliasi
sp. nov.
A–C, UMJGP 21.1339 with partially degraded cuticular surfaces (B–C). Specimen in A was coated with ammonium chloride prior the photography.
Iphiculus eliasi
sp. nov.
also resembles some
Typilobus
species.
Typilobus kishimotoi
Karasawa, 1998
, from the Miocene of
Japan
has similarly shaped carapace outline and possesses large rounded tubercles on the dorsal surface; but the tubercles are fewer than in
I. eliasi
sp. nov.
(
Fig. 3
A vs.
Karasawa 1998
: fig. 2). Additionally,
T. kishimotoi
has two longitudinal ridges behind the median sulcus of the frontal region (
Karasawa 1998: fig. 2.2b
), a feature that is absent in the new species (
Figs. 2
A, 3A, 3C).
One specimen of
Iphiculus eliasi
sp. nov.
(UMJGP 21.1339) exhibits partial cuticle degradation on the preserved portion of the carapace (
Fig. 4
A–C). It suggests rather complex internal structure of the tuberculation of leucosioids; tubercles are expressed differently in various cuticular layers. It was already noted that taphonomic aspects of the cuticle preservation in fossil crabs may have major impact on taxonomical evaluation of the characters such as carapace ornamentation (e.g.
Feldmann & Portell 2007
;
Klompmaker
et al.
2015
). Therefore, only large rounded tubercles present also on the specimen without preserved cuticle (
Fig. 3
A–D) are considered of taxonomical importance herein.
Vía (1941)
reported an “
Iliinae
,
Ebaliinae
?” from the Middle Miocene of
Catalonia
,
Spain
. His figure (
Vía 1941: pl. 10, fig. 75
) clearly represents a leucosioid crab with striking similarities to
Iphiculus eliasi
sp. nov.
Müller (1993: figs 5M–N)
refigured the specimen in greater detail (although still insufficient for closer comparison) and assigned it questionably to the leucosiid genus
Randallia
Stimpson, 1857
sensu lato
(see
Galil 2003
). Re-examination of the specimen is needed to resolve its affinities.