Cenomanocarcinus cristatus ( Jux, 1971 )

Guinot, Danièle, Vega, Francisco J. & Van Bakel, Barry W. M., 2008, Cenomanocarcinidae n. fam., a new Cretaceous podotreme family (Crustacea, Decapoda, Brachyura, Raninoidia), with comments on related families, Geodiversitas 30 (4), pp. 681-719 : 681-719

Cenomanocarcinus cristatus ( Jux, 1971) ( Fig. 7 )

MATERIAL EXAMINED. — Afghanistan, upper Campanian : holotype, female 47 × 46 mm (without lateral spines) ; the specimen was squeezed transversely and deformed, as shown by the asymmetrical carapace ( GIK 538 ) ( GIK 536 in Jux 1971) .

Remarks

Jux (1971: 157, fig. 2, pl. 17) established a new genus, Hasaracancer (type species H. cristatus Jux, 1971 ) from the upper Campanian of Afghanistan, described as a raninid and thus assumed to be a podotreme crab. It was transferred to the Necrocarcinidae by Schweitzer et al. (2003a: 32, 33; 2004: 90, table 1) and Schweitzer & Feldmann (2005: tables 4, 5, 7), a heterotreme family according to those authors. The elongate and narrow carapace ( Fig. 7B ) is obviously deformed, without lateral spines preserved. The dorsal surface bears an axial ridge with fairly large tubercles and two long lateral ridges lined by small, close-set tubercles; the orbits are small, closely spaced. The superficial resemblance in carapace outline and ornamentation between H. cristatus and Necrocarcinus renfroae Stenzel, 1945 ( Stenzel 1945: pl. 41, fig. 13) ( Fig. 8B, D ) is likely due to a similar style of deformation. The mxp3 and sternum are absent in H. cristatus while the abdomen ( Fig. 7A ) apart from the telson is entirely preserved. The abdomen is extremely wide (even for a female) and unfolded (at least somites 1 to 4 in line with the carapace, thus dorsal; only a slight folding posteriorly; with somites 1-6 of the same width, 2-5 being conspicuously inclined laterally; somite 1 very short, somite 6 strongly developed). The curved lateral parts were compared to pleurae by Jux (1971: 161), who placed Hasaracancer with the Raninoidea , close to Notopocorystes McCoy, 1849 . The incompletely folded

and partially dorsal abdomen of H. cristatus is the possible product of the holotype being an exuvia, rather than a corpse. The abdomen is interpreted to have been normally folded underneath the carapace, as in other species of Cenomanocarcinus . Despite the presence of a near complete cervical groove which distinctly delineates the anterior part of the carapace in H. cristatus , Hasaracancer is referred herein to Cenomanocarcinus .

Figures

FIG. 7. — Cenomanocarcinus cristatus (Jux, 1971), upper Campanian, Afghanistan, holotype of Harasacancer cristatus (specimen squeezed transversely and deformed), female 47 × 46 mm (without lateral spines) (GIK 538): A, side view; B, dorsal view. Scale

FIG. 8. — A-D, “Necrocarcinus” renfroae Stenzel, 1945, Early Cretaceous, upper Albian, Texas, Pawpaw Formation; A, B, paratype (BEG-21094-A3), frontal and dorsal views; C, D, holotype (BEG-21093-A3), frontal and dorsal views; E, F, Necrocarcinus labeschii (Deslongchamps, 1835), Albian, Calais, Escalles, northwest France (B. van Bakel Colln), left chela and carapace. Scale