Bucculentum bachmayeri Schweitzer & Feldmann, 2009

Krzemińska, Ewa, Starzyk, Natalia, Fraaije, René H. B., Schweigert, Günter & Lukeneder, Alexander, 2021, Jurassic brachyurans of the genus Bucculentum, Zootaxa 5032 (3), pp. 395-410 : 401-402

Bucculentum bachmayeri Schweitzer & Feldmann, 2009

Fig. 1C, D , 5

2009a Bucculentum bachmayeri in: Schweitzer & Feldmann, Ann. Naturhist. Mus. Wien 110 A: 81, fig. 1.4, 3.1, 3.2. Diagnosis. Carapace widest across hepatic regions which are more expanded laterally than in Bucculentum bucculentum , but flattened (in frontal view); augenrest positioned perpendicular to body long axis, bounded by small tubercles on outer-orbital edge; suborbital spine bifid, its two prongs being thin and long; cardiac region small, ovate, with one dominant, sharp tubercle.

Material examined. Holotype, NHMW 1990 /0041/3376, near Dörfles, Vienna, Ernstbrunn Limestone, Tithonian. Specimen SMNS 70606 : Bad Überkingen-Oberböhringen near Geislingen an der Steige , southern Germany (N 48 o 61’, E 9 o 79’); Upper Kimmeridgian, Pseudomutabilis Zone (leg. H. Kuschel).

Additional description. The frontal view of the holotype exposes a very characteristic feature of this species: the hepatic regions are broad and flattened when compared to B. bucculentum , so that the distance between the upper margin of the augenrest and the surface of the hepatic region over it is very short (marked with an arrow in Fig. 5A ); the same character is visible in the specimen SMNS 70606 ( Fig. 5C , arrow). The area of the augenrest is flat and smaller than in B. bucculentum ; the plane of the augenrest is perpendicular to the long body axis, similar to B. bucculentum . The suborbital spine in the holotype is bifid, and its two prongs are thin ( Fig. 5B ); in the specimen SMNS 70606 these spines are not preserved. The lateral sides of carapace are endowed with strong, short spurs partially preserved in SMNS 70606 ( Fig. 5E, F ).

The known specimens delimit the range of this species to Late Kimmeridgian-Tithonian.

Figures

FIGURE 1. Nomenclature of carapace and ground plans of species of Bucculentum: A, B, Bucculentum bucculentum (dorsal and frontal view, respectively); C, D, Bucculentum bachmayeri (dorsal and frontal view, resp.); E, F, Bucculentum horstkuscheli, n. sp. (dorsal and frontal view, resp.); G, Bucculentum plettenbergense, n. sp., dorsal view (a, augenrest; ag, augenrest groove; bcg, branchio-cardiac groove; c, cardiac region; cg, cervical groove; h, hepatic region; ebr, epibranchial region; mbr, metabranchial region; mg, mesogastric region; msbr, mesobranchial region; pcg, postcervical groove; s, suborbital spine).

FIGURE 5. Bucculentum bachmayeri. A–B, holotype NHMW 1990/0041/3376 (Tithonian): frontal view (A, short distance over augenrest is arrowed), suborbital spine (B, arrow). C, specimen #SMNS 70606 Bad Überkingen-Oberböhringen (Late Kimmeridgian). Bars 1 mm.