Folguerolesia boscoi ( Vía Boada, 1959 ) Via Boada, 1959

Artal, Pedro & Hyžný, Matúš, 2016, An appraisal of Typilobus Stoliczka, 1871 (Crustacea, Brachyura, Leucosioidea), with description of a new family and genus, Zootaxa 4117 (3), pp. 387-398 : 393-396

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.

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.

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.

Figures

FIGURE 2. Morphological variation shown in several species assigned to Typilobus. A, Typilobus marginatus Morris & Collins, 1991, holotype NHMUK In 62163 in dorsal (A 1) and ventral view (A 2); B – C, Typilobus sadeki Withers, 1925, holotype NHMUK In 22991 (B) and In 22992 (C) in dorsal (B 1, C 1) and ventral views (B 2, C 2); D, Typilobus belli Quayle & Collins, 1981, holotype NHMUK In 61707; E, Typilobus moralejai Müller, 1993, holotype MGSB 51918; F, Typilobus cf. corrodatus Noetling, 1885, BSPG 1981 XI 15. Specimens in E and F were coated with ammonium chloride prior the photography. Scale bar equals 5 mm.

FIGURE 3. Folguerolesia boscoi (Vía Boada, 1959) comb. nov. A, MGSB 15932 (holotype, indeterminate sex), in dorsal (A 1), postero-dorsal (A 2) and lateral (A 3) views; B, MGSB 79789 (female), in dorsal view under different light conditions (B 1, B 2), in lateral view (B 3), in frontal view (B 4), in posterior view (B 5), and ventral view (B 6); MGSB 79790 (male), in dorsal (C 1), postero-dorsal (C 2), lateral (C 3), and ventral view (C 4). All specimens were coated with ammonium chloride prior the photography. All specimens are to scale. Scale bar equals 5 mm.

FIGURE 4. Folguerolesia boscoi (Vía Boada, 1959) comb. nov. A, MGSB 79790, ventral view of a male, with (A 1) and without (A 2) ammonium chloride; B, MGSB 79789, ventral view of a female, with (B 1) and without (B 2) ammonium chloride. Scale bar equals 5 mm.