Campylostoma Bell, 1858

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

?Genus Campylostoma Bell, 1858 ( Fig. 1C, D )

MATERIAL EXAMINED. — Lower Eocene (Ypresian), London Clay, Isle of Sheppey, casts of 2 carapaces ( MNHN R03315), 1 carapace (B. van Bakel Colln).

Remarks

Campylostoma Bell, 1858 (type species by monotypy: Campylostoma matutiforme Bell, 1858: 23 , pl. 3, figs 8-10, from lower Eocene, Ypresian, of southern England; see also Carter 1898: 30), previously assigned to the Calappidae De Haan, 1833 ( Bell 1858: 23; Lőrenthey 1929: 300, fig. 20c; Glaessner 1969: R494, fig. 305.1; Feldmann 1993: 208), later to the Necrocarcinidae as a calappoid family ( Förster 1968: 181; Schweitzer & Feldmann 2000: 246, key, fig. 1; Collins 2002: 85; Fraaije 2002: 914; Schweitzer & Feldmann 2005: 34), was finally considered to be a dorippoid representative ( Schweitzer et al. 2003a: 32).

The remarkably well-preserved specimens of C. matutiforme found in a London Clay nodule ( Collins 1961: 85, pl. 12, figs 1, 1a, 3, 3a) are much smaller (carapace length 13.3 mm) than the type series (carapace length 32.5 mm), yet show the same long epibranchial spine “produced to a length equal to three-quarters of the carapace width” ( Collins 1961: 85). Thus the mention of an epibranchial spine as “unnaturally developed” or “hypertrophied” ( Bell 1858: 23 footnote and caption of fig. 9 in pl. 3) is not justified, nor is the representation of nearly equal-sized anterolateral spines in reconstructions by Salter & Woodward (1865) and Schweitzer & Feldmann (2000: fig. 1), which have led to a misrepresentation of Campy-

lostoma carapace outline.

The epibranchial spine in C. matutiforme ( Fig. 1D ) is better developed and more inclined posteriorly than in species of Cenomanocarcinus . Like in Cenomanocarcinus , the buccal cavity of Campylostoma is “narrowed forwards in a curved line”, and the mxp3 consists of an elongate endopodite ischium and broad exopodite ( Bell 1858: 23, pl. 3, fig. 10). Additionally, the close-set and narrow orbits and pterygostomian regions are similar in Campylostoma and Cenomanocarcinus . The monotypical genus Campylostoma is removed herein from the Dorippoidea and transferred among the podotreme crabs, as a possible cenomanocarcinid.

Necrocarcinus bispinosus Segerberg, 1900 ( Segerberg 1900: 372, pl. 9, fig. 7), from the Danian of Scandinavia, considered to belong to Campylostoma ( Fraaije 2002: 913) , possesses on each side of the carapace a nearly complete epibranchial spine which is strongly produced, located posteriorly on the lateral border and directed obliquely.

REMARKS ON SPECIES PREVIOUSLY ASSIGNED

TO CENOMANOCARCINUS

Figures

FIG. 1. — A, B, E, F, Cenomanocarcinus inflatus Van Straelen, 1936, upper Cenomanian, Le Mans; C, D, Campylostoma matutiforme Bell, 1858, lower Eocene (Ypresian), London Clay, Isle of Sheppey (B. van Bakel Colln); A, B, paralectotype, 44 × 52 mm (MNHN R05504);E, F, topotypical specimen, 27 × 38 mm, estimated width at least 40 mm by including complete epibranchial spines (MHN LM 3806);E, dorsal carapace with partially preserved epibranchial spines;A, frontal view; B, dorsal carapace;C, frontal view;D, dorsal