An appraisal of Typilobus Stoliczka, 1871 (Crustacea, Brachyura, Leucosioidea), with description of a new family and genus
Author
Artal, Pedro
Author
Hyžný, Matúš
text
Zootaxa
2016
4117
3
387
398
journal article
38953
10.11646/zootaxa.4117.3.6
6d80337f-4669-4d0c-9a6b-97be42d7b7f2
1175-5326
266705
115D5789-D296-44AD-B76A-C71F88BE3586
Folguerolesia boscoi
(
Vía Boada, 1959
)
comb. nov.
(
Figs 3
,
4
)
Typilobus boscoi
Vía Boada, 1959
: 370
, fig. 10; 1969: 153, fig. 19, pl. 10, figs 1–5;
Karasawa, 1998
: 99
;
Schweitzer
et al
., 2010
: 91
(list);
Feldmann
et al
., 2011
: 327
(list)
Diagnosis
. As for genus.
Emended description.
Small carapace; from subcircular to longitudinally elliptical in outline; only slightly longer than wide, widest anteriorly, at level of epibranchial region; dorsal surface strongly convex in both directions. Front slightly projected, somewhat raised, narrow, bilobed, with slight axial depression. Front with downturned apex. Orbits small, subcircular, anteriorly directed. Lateral margins broadly arched, bearing 5 strong spines, the last one conspicuously long. Posterior margin short, with 2 long lateral spines. Dorsal carapace surface very well defined by strong swellings, well-marked grooves. Gastric regions undifferentiated, strongly swollen. Hepatic region small, subtriangularly elongated, with 2 small lateral spines, slightly swollen, bounded by marked cervical, hepatogastric grooves. Cardiac region strongly swollen, with strong axial subconical protuberance; separated from gastric region by deep groove. Branchial regions swollen, globose, not divided into portions. Intestinal region small, flat. Cervical groove well marked, continuous from side to side, notching lateral margins. Branchial groove deep. Dorsal carapace surface densely, uniformly covered by pearl-like granules. Sternum broad, longitudinally oval, lateral margins slightly raised, densely granular in females. Sternites 1–4 fused, sternites 1–3 strongly downturned. Episternites long, granular, with vertical margins. Female pleonal segments broadly ovate, nearly covering complete sternum, all segments free. Male pleonal segments subtriangular, narrow, with pleonal segments 3–4 fused, telson short, conspicuously reduced, scarcely reaching sternite 4. Anterior portion of pleonal cavity narrow, long, nearly reaching sternite 2. Pereiopod coxae large, condyles stout, gynglimes adapted for pereiopods.
FIGURE 3
.
Folguerolesia boscoi
(Vía Boada, 1959)
comb. nov.
A, MGSB15932 (holotype, indeterminate sex), in dorsal (A1), postero-dorsal (A2) and lateral (A3) views; B, MGSB79789 (female), in dorsal view under different light conditions (B1, B2), in lateral view (B3), in frontal view (B4), in posterior view (B5), and ventral view (B6); MGSB79790 (male), in dorsal (C1), postero-dorsal (C2), lateral (C3), and ventral view (C4). All specimens were coated with ammonium chloride prior the photography. All specimens are to scale. Scale bar equals 5 mm.
Material examined.
The
holotype
of indeterminate sex,
MGSB
15932 (max. carapace length 9.6 mm; max carapace width 9.4 mm); one female specimen,
MGSB
79789 (max. carapace length 9.1 mm; max. carapace width 8.9 mm); one male specimen,
MGSB
79790 (max. carapace length 6.3 mm; max. carapace width 5.8 mm); a partially preserved female specimen,
MGSB
79791.
Occurrence.
The species is known only from the Middle Eocene (middle Lutetian) of the Vic area, (Barcelona,
Spain
) and Girona Province (Catalonia).
Remarks
.
Folguerolesia boscoi
appears to be morphologically close to some species of
Typilobus
that were described from Paleogene strata. Representatives of this group share several common features. The carapace is somewhat longer than wide, with subcircular or longitudinally subelliptical outline; dorsal grooves are strongly marked; the hepatic region is elongated and subtriangular in outline; and the gastric area is fairly elongated. Some of these species bear pronounced teeth or spines on the lateral, postero-lateral, and/or posterior margins of the carapace.
FIGURE 4
.
Folguerolesia boscoi
(Vía Boada, 1959)
comb. nov.
A, MGSB79790, ventral view of a male, with (A1) and without (A2) ammonium chloride; B, MGSB79789, ventral view of a female, with (B1) and without (B2) ammonium chloride. Scale bar equals 5 mm.
Typilobus trispinosus
is rather close to
Folguerolesia boscoi
. The hepatic regions are subtriangular elongated, the gastric region is distinctly longer than wide, the spines on the posterior margin are conspicuously long, and the cardiac spine is not very different from the conical protuberance seen in
F. boscoi
.
Typilobus trispinosus
differs by the absence of lateral spines, the possession of more prominent cardiac spine and the gastric region reaching a strong posterior placement.
Typilobus corrodatus
and
T. semseyanus
appear to be close to
F. boscoi
.
Unfortunately, as already mentioned by
Feldmann
et al
. (2011
: 328) these species were illustrated by sketches and the descriptions are not detailed enough. A recovered specimen from the Eocene of
Italy
was directly compared with a cast of the
type
specimen of
T. semseyanus
and was assigned to this species (
Beschin
et al
. 1998
: 17, fig. 6). Characters such as the complete dorsal surface densely covered by pearl-like granules, the general outline, the shape and distribution of dorsal regions, and grooves, are shared with
F. boscoi
.
Typilobus corrodatus
and
T. semseyanus
, however, have carapace granulation with larger spaces between the granules, the front with a deep median notch, and no lateral spines.
Typilobus granulosus
has a proportionally wider carapace and a different position of the lateral spines, which are fewer and less well developed than those of
F. boscoi
. The branchial nodes are blunt and disposed dorsally, a feature not seen in
F. boscoi
.
Typilobus sadeki
Withers, 1925
, having a similar carapace outline as
T. granulosus
, has dorsal grooves that are less marked than those in
F. boscoi
, and the hepatic region is larger and more equidimensional. The male and female pleon is subtriangular, narrow, with all pleonal segments free in
T. sadeki
; the telson is conspicuously long in both sexes (
Fig. 2
B2–C2).
Typilobus marginatus
Morris & Collins, 1991
, differs from
F. boscoi
in a number of characters. The former species has the carapace with a strongly transversely elliptical outline, distinctly wider than long, less pronounced dorsal grooves, different distribution of dorsal regions, and does not have strong lateral spines (
Fig. 2
A).
Typilobus modregoi
exhibits a moderately vaulted carapace, without lateral spines, and the posterior margin bear two small, blunt protuberances, the dorsal surface present very weak grooves.
Typilobus belli
Quayle & Collins, 1981
, appears to be subcircular in outline, with a carapace broader than wide, the gastric area is much less elongated, the lateral margins lack spines and the two posterior spines are distinctly smaller (
Fig. 2
D).
Typilobus obscurus
Quayle & Collins, 1981
, is similar to
T. belli
, with a rounded carapace, wider than long; branchial and cardiac regions that are larger and swollen; and lateral and posterior margins without spines.
Typilobus alponensis
Beschin, De Angeli & Zorzin, 2009
, appears to represent a distinct morphotype on its own. The front is much more projected, the subcircular outline of the carapace lacks lateral spines, the posterior margin bears two blunt protuberances instead of spines; the cardiac region is more anteriorly situated, and the intestinal region larger (
Beschin
et al
. 2009
: 72, pl. 3, fig. 1).
Typilobus alponensis
may deserve re-assignment to a new genus, different from
Typilobus
. Better preserved material and presence of ventral portions can resolve this issue.