Bournelyreidus tridens ( Roberts, 1962 ) 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 : 83

Bournelyreidus tridens ( Roberts, 1962) n. comb.

Raninella tridens Roberts, 1962: 187 .

( Fig. 23B )

Material examined. Casts of GAB 37-832 (ventral) and GAB 37-833 (dorsal) ( Bishop 1983b: fig. 3l; table 1) ( MAB k.0214).

Remarks. Raninella tridens (see Roberts 1962: 187, pl. 88, figs. 5, 6), from the Campanian of New Jersey and Delaware, U.S.A. and the lower Maastrichtian of Mississippi ( Bishop 1983b), is here transferred to Bournelyreidus n. gen. The carapace is small, elongated, and the cuticle shows fine granules (upright nodes). The orbital margin is horizontal, branchiocardiac grooves are weak, the median third of the carapace has vertical margins, the posterior portions of the posterolateral margin being divergent and slightly concave. Sternite 3 is crown shaped, sternite 4 is long, with strongly concave lateral margins and it joins the pterygostome anteriorly. The posterior corner of the pterygostome is recessed for the rather small mxp3 coxa. Episternites 4 small, separated by distinct, crescentshaped sutures. Sternite 5 is comparatively large, widened anteriorly and with two small depressions posteriorly; the episternites show rather short, curved projections. No pegs are discernible, which may be the result of incomplete preservation, or the specimen represents a mature female in which the holding was lost. The projections are curved outwards, and seem to ‘rest’ on the surface of sternite 6; such configuration suggests the specimen to be a mature female. Only the anterior portion of sternite 6 is preserved; it is strongly excavated. In Lyreidinae the surface in between these projections and the anterior portion of sternite 6 is typically excavated as a kind of sternoabdominal depression. No medial line is present on sternites 1‒6, a characteristic of the genus. Exposed pleurites 5 and 6 are preserved; they are rather low, and notably granular.

Figures

FIGURE 23. A, C, Bournelyreidus laevis (Schlüter in von der Marck & Schlüter, 1868) n. comb. (Lyreididae, Lyreidinae), MAB k. 2882 (cast of RME 551.763.333; indeterminate sex), upper Santonian, Erkenschwick (Münsterland, northwestern Germany); left lateral view, and dorsal view of carapace; B, Bournelyreidus tridens (Roberts, 1962) n. comb., MAB k. 0214 (cast of GAB 37–833; indeterminate sex), lower Maastrichtian, Mississippi (U.S.A); dorsal view of carapace. Scale bars: 5mm.