Laeviprosopon sublaeve (von Meyer, 1860)

Starzyk, Natalia, Van Bakel, Barry W. M., Klompmaker, Adiël A., Schweigert, Günter & Fraaije, René H. B., 2023, A new approach to the systematics of Laeviprosopon (Brachyura: Homolidae), with remarks on the molting process of early brachyurans, Palaeontologia Electronica (a 10) 26 (1), pp. 1-24 : 7-9

Laeviprosopon sublaeve (von Meyer, 1860)

Figure 1

1857 Prosopon sublaeve von Meyer , p. 556.

1860 Prosopon sublaeve von Meyer. – von

Meyer, p. 209, pl. 23, figure 23.

1925 Prosopon sublaeve von Meyer. – Beurlen,

p. 484, 485.

1929 Prosopon laeve var. sublaevis von Meyer.

– Glaessner, p. 344.

1933 Laeviprosopon laeve var. sublaevis (von

Meyer). – Glaessner, p. 180.

1988 Laeviprosopon sublaeve (von Meyer) . –

Wehner, p. 119, text-figure 32, pl. 8, figure

3.

Diagnosis. (After Schweitzer and Feldmann 2008, emended). Carapace longer than wide, rectangular; front broadly convex; orbits well-developed for genus; regions ornamented with tubercles and larger nodes, especially posteriorly, five tubercles on each side of mesogastric region.

Discussion and type designation. Laeviprosopon sublaeve was described by von Meyer (1860), who illustrated a drawing of a specimen from Oerlinger Thal near Ulm (late Kimmeridgian). He drew transverse grooves dividing areas laying on both sides of the mesogastric region on epigastric, protogastric, hepatic and subhepatic regions and five tubercles laying on each side of the mesogastric region. Both on the drawing and in the description (translated in Schweitzer and Feldmann, 2008), the transverse grooves are present. Unfortunately, all of the six syntypes of von Meyer are lost, so that there is no possibility left to select a lectotype.

Wehner (1988) illustrated a specimen (GPIT- PV-51741) of Laeviprosopon sublaeve from Oerlinger Thal housed in the Museum of the University in Tübingen. Wehner cited the label with the wrong information: the mentioned specimen is not one of the specimens illustrated by Quenstedt (1857, pl. 95) and probably not illustrated in later books of Quenstedt (see Quenstedt 1885, pl. 31, fig. 21). As this information was erroneous, we cannot be sure if the locality described as Oerlinger Thal is right. However, as all six syntypes are lost, we here designate the specimen described by Wehner as a neotype. Its current number in the paleontological collection of Tübingen University is GPIT-PV-51741 .

The specimen has all the diagnostic characters described and drawn by von Meyer. On the photo published by Wehner, two tubercles seem to be visible on each side of the mesogastric region, while the drawing made by Wehner (who studied the actual specimen) shows only one tubercle on each side (Wehner, 1988, figure 32B, C; pl. 8, figure 3).

The specimens assigned to L. sublaeve by Schweitzer and Feldmann (2008, figure 1.10 and 1.11, herein Figure 6 ) differ. Both specimens have transverse grooves between the cervical and branchial groove, which are absent in the specimens described by von Meyer (1860) and Wehner (1988). From the neotype specimen we consider it is barely possible that both von Meyer and Wehner could have overlooked the presence of these grooves on their drawings and descriptions. As specimens NHMW 1990/0041/4051 and NHMW 1990/0041/3295 described by Schweitzer and Feldmann (2008) are most similar to Laeviprosopon fraasi , we consider them to represent this species (see text below and Figure 6 ).

Figures

FIGURE 1. Stratigraphic range of the species herein considered within Laeviprosopon with schematic drawings of all the species.

FIGURE 6. Laeviprosopon fraasi A - NHMW 1990/0041/3295, Ernstbrunn; B - NHMW 1990/0041/4051, Ernstbrunn; C - holotype, BSP AS III 309, Štramberk; D - NHMW 1990/0041/3295; E - NHM W1990/0041/4051; F - holotype, BSP AS III 309. Orbital margin marked with an arrow. lh – linea homolica. Scale bars equal 1.0 mm.