Calappidae, De Haan, 1833

Schweitzer, Carrie E. & Feldmann, Rodney M., 2010, New fossil decapod crustaceans from the Remy Collection, Muséum national d’Histoire naturelle, Paris, Geodiversitas 32 (3), pp. 399-415 : 404-405

Calappidae gen. et sp. indet. ( Fig. 1C, D )

MATERIAL EXAMINED. — Carapace ( MNHN R03836, coll. Milne-Edwards).

MEASUREMENTS. — Measurements (in mm) taken on the dorsal carapace of MNHN R03836: maximum carapace width = 35.8; maximum carapace length> 33.0; frontoorbital width = 19.7; frontal width = 7.5.

OCCURRENCE. — Paleogene rocks of Dax, Landes, in Aquitaine, France.

DESCRIPTION

Carapace ovate, about as wide as long, widest at about midlength; moderately vaulted both longitudinally and transversely.Front narrow, about 20% maximum carapace width, broken.Orbits directed forward; rims unknown; fronto-orbital width 55% maximum carapace width. Anterolateral and posterolateral margins confluent; anterolateral portion appearing to have had small spines or protuberances; posterolateral portion possibly rimmed; posterior margin broken.

Protogastric regions weakly inflated, merged with mesogastric region.Metagastric and urogastric regions confluent, about same height as mesogastric region, lateral margins concave. Cardiac region roundedtriangular, elongate, two swellings anteriorly. Lateral margins bounded by deep, lateral groove. Intestinal region poorly defined.Hepatic region weakly inflated centrally.Epibranchial region arcuate,weakly inflated. Remainder of branchial regions undifferentiated.

Th ird maxillipeds elongate.

Male sternum long, narrow. Sternites 1-2 fused, no evidence of suture, triangular, separated from sternite 3 by complete suture. Sternite 3 about as long as wide, deeply depressed axially, separated from sternite 4 by deep, oblique grooves. Sternite 4 much longer than wide, deeply grooved axially, sterno-abdominal cavity extending about one-quarter the distance onto sternite, with short episternal projections, directed anterolaterally. Sternite 5 wider than long, suture 4/5 incomplete, with short episternal projections, directed laterally; sternite 6 wider than long, suture 5/6 incomplete, with short episternal projections, directed posterolaterally; sternite 7 wider than long, suture 6/7 incomplete, directed strongly posterolaterally; sternite 8 short, wide; directed strongly posterolaterally, suture 7/8 may or may not have been incomplete: preservation insufficient to determine.

Remainder of carapace and appendages unknown.

DISCUSSION

The specimen described here appears to be referable to the family based upon its ovate shape; closely spaced, circular orbits; well-defined axial regions that are bounded by deep grooves; narrow sternum with deep sterno-abdominal cavity; and sternal sutures 4/5 and 5/6 definitely interrupted. The specimen described here seems to lack posterolateral spines, eliminating it from the speciose Eocene genus Calappilia and also from Calappa , but those margins are heavily damaged. Species of Mursia generally have granular ornamentation on the dorsal carapace, which the specimen described here lacks. However, the specimen is damaged on all of the margins, so it is not possible to place it within a genus. Although the dorsal carapace is poorly preserved, the sternum is quite well preserved. Recovery of more specimens will help to place this specimen within a taxon.

Figures

FIG. 1. — Fossil Brachyura from Monségur (Gironde, France): A, Remyranina ornata (Remy, 1960) n. comb., cast of holotype, MNHN R03847, dorsal carapace; B, Calappilia? gorodiskii (Remy in Gorodiski & Remy, 1959) n. comb., cast of holotype, MNHN R03840, dorsal carapace; C, D, Calappidae gen. et sp. indet., dorsal (C) and ventral (D) surfaces, MNHN R03836; E, Mursia simplex (Remy, 1960) n. comb., cast of holotype, MNHN R03849, dorsal carapace; F, Szaboa lamarei n. sp., holotype, MNHN R03779, dorsal carapace. Scale bars: 1 cm.