Laeviprosopon, Glaessner, 1933

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 : 4

Genus LAEVIPROSOPON Glaessner, 1933

Type species. Prosopon laeve von Meyer, 1860 , by original designation.

Other species included. Laeviprosopon crassum Klompmaker, 2013 ; L. edoi Klompmaker, 2013 ; L. ewakrzeminskae n. sp.; L. fraasi (Moericke, 1889) as Prosopon ; L. grandicentrum Schweitzer and Feldmann, 2008 ; L. hispanicum Klompmaker, 2013 ; L. icaunensis (Van Straelen, 1936) as Prosopon ; L. joecollinsi n. sp.; L. laculatum Schweitzer and Feldmann, 2008 ; L. lazarae Franţescu, 2011 ; L. lanceatum n. sp.; L. musialiki Starzyk, 2020 ; L. planum Klompmaker, 2013 ; L. punctatum (von Meyer, 1860) as Prosopon ; L. sublaeve (von Meyer, 1860) as Prosopon .

Diagnosis. As in Klompmaker (2013). “Carapace rectangular, typically longer than wide, often narrowing slightly anteriorly; regions well-defined by deep grooves; rostrum variable, projected well beyond orbits; orbits shallow, rimmed, directed forward, located at base of rostrum; augenrest poorly formed to nearly absent; subhepatic region inflated, sometimes greatly; epigastric region separated from protogastric and hepatic regions by transverse groove; hepatic and protogastric regions confluent or partly divided by groove on lateralmost part of dorsal carapace; cervical groove deep, strongly concave forward to sinuous; branchiocardiac groove usually shallower than cervical groove; post-cervical groove usually short; posterolateral portions of carapace often broken as if less calcified than other portions of carapace.” Remarks. As was mentioned in the introduction, the systematic position of Laeviprosopon has changed several times. Authors that did not confirm the presence of linea homolica placed it in the family Prosopidae (superfamily: Homolodromioidea ), while authors that confirmed the presence of this structure in L. laeve placed the genus in the family Homolidae (superfamily: Homoloidea ). In this paper, we show unequivocal evidence of the presence of linea homolica in three Late Jurassic representatives of Laeviprosopon . Eleven new specimens of L. laeve represent molds with clearly visible molting lines similar to a linea homolica, which is also present on the carapaces of L. fraasi and L. laculatum . Specimens of four Cretaceous species of Laeviprosopon ( L. hispanicum , L. planum , L. edoi and L. crassum ) are also molds presenting the same type of molting line. These observations are sufficient to reassign Laeviprosopon to the family Homolidae as it includes the oldest known brachyurans with a linea homolica (see chapter Discussion for more details).