Bournelyreidus teodorii, Van Bakel & Guinot & Artal & Fraaije & Jagt, 2012

Van Bakel, Barry W. M., Guinot, Danièle, Artal, Pedro, Fraaije, René H. B. & Jagt, John W. M., 2012, A revision of the Palaeocorystoidea and the phylogeny of raninoidian crabs (Crustacea, Decapoda, Brachyura, Podotremata) 3215, Zootaxa 3215 (1), pp. 1-216 : 81-82

Bournelyreidus teodorii n. sp.

( Fig. 24A )

Diagnosis. Carapace large, oval, elongated, widest at one-third of total carapace length from front. Posterolateral margin with divergent posterior portion; anterolateral margin shorter, with 2 small teeth. Orbitofrontal margin tridentate, occupying about half of maximum carapace width. Outer orbital corners prominent, supraorbital borders with 2 orbital notches. Rostrum triangular, bifid, excavated. Carapace surface with minute pits and granules.

Derivation of name. Named in honour of Mr Dominique Téodori (Pechbonnieu, France), who collected and donated the specimen.

Material examined. Holotype ( MNHN.F A38533 ) collected at working quarry southeast of the village of Saint-Loup-en-Comminges (Haute-Garonne, Midi-Pyrénées, southwest France; September 2009), from a bluegrey marly limestone bed at the base of a series assigned to the ‘Marnes bleues de Saint-Loup’. A second specimen in the private collection of D. Teodori has also been examined; this retains a better-preserved anterolateral and frontal margin, so that features of the holotype could be checked and confirmed. Co-occurring macrofaunal assemblages are rich in holasteroid echinoids, ostreid bivalves, fishes, cephalopods (e.g., the scaphitid ammonite Hoploscaphites constrictus ( Sowerby, 1817) and other unidentified crustaceans. The thickness of such limestone levels varies between 0.1 and 0.3 m; they alternate with softer marls. As noted by Kennedy et al. (1986: 1004, 1005, fig. 2) and Peybernès et al. (1998), the ‘Marnes bleues de St. Loup’ in the Blajan-Bazordan anticline are of late Maastrichtian age.

Description. Carapace large (maximum length 66 mm, width 40 mm), oval, elongated, widest behind the lateral spines at about at one-third of total carapace length from front. Orbitofrontal margin tridentate, occupying about half of maximum carapace width. Base of rostrum about one-third of orbitofrontal region. Rostrum triangular, bifid, excavated. Large subcircular orbits with prominent outer orbital spines. Supraorbital borders with 2 relatively deep orbital fissures. Posterolateral margin with diverging posterior portion; anterolateral margin shorter, with 2 rather small, forwardly directed spines. Branchiocardiac grooves, impressions of epimeral adductor muscle scars faint. Carapace surface with minute pits, granules. Granules significantly coarser along lateral margins. Both chelipeds similar in size, form; merus, carpus, propodus of comparable length, width, covered with granules; propodus distinctly more flattened.

Remarks. Despite the fact that the carapace has suffered from sediment compaction, the morphology of the orbitofrontal and anterolateral margins allows assignment of this form to Bournelyreidus n. gen. It is distinguished from B. carlilensis n. comb. and B.? oaheensis n. comb. in attaining a markedly larger size and in having a less broad orbitofrontal region and a much larger carpus. Bournelyreidus tridens n. comb. has a much shorter anterolateral margin, and a more projected orbitofrontal region; its posterolateral margins are more concave and less divergent than the new species. Bourneylyreidus manningi n. comb. has much coarser ornamentation and a more clearly areolated carapace. The new species differs from B. laevis n. comb. in having a broader base to the rostrum and subcircular orbits rather than near-rectangular ones; it can also be distinguished from B. eysunesensis n. comb. by its less concave anterolateral margin between the outer orbital and first anterolateral spine.

Figures

FIGURE 24. A, Bournelyreidus teodorii n. sp. (Lyreididae, Lyreidinae), MNHN.F A38533 (holotype; ex D. Téodori Collection); middle/upper Maastrichtian, Saint-Loup-en-Comminges (Haute-Garonne, southern France); dorsal view of carapace and chelipeds; B, Lyreidus tridentatus De Haan, 1841 (Lyreididae, Lyreidinae), MAB k. 2883 (male), Recent, Philippines; dorsal view of carapace. Scale bars: A: 10mm; B: 5mm.