A NEW POROLEPIFORM-LIKE FISH, PSAROLEPIS-ROMERI, GEN. ET SP. NOV. (SARCOPTERYGII, OSTEICHTHYES) FROM THE LOWER DEVONIAN OF YUNNAN, CHINA

A new sarcopterypian fish, Psarolepis, gen. nov. (Sarcopterygii, Ostei chthyes) is described from the Lower Devonian of Eastern Yunnan, China . The new genus manifests many porolepiform-like features that are com monly used to distinguish porolepiforms from osteolepiforms, such as i nternasal cavity well developed, parasphenoid not protruding forward t o ethmoidal region, vomeral area rectangular in shape and not meeting at median line, dorsal part of interorbital wall broad and tectum orbi tale well developed, external surface of lower jaw with three large fo ssae, and well developed parasymphysial plates at anterior tip of lowe r jaws. This new form also shares some features with Powichthys, Young olepis and Diabolepis that are not found in typical porolepiforms, suc h as intracranial joint situated at the level of the trigeminal exit, posterior face of ethmosphenoid facing posteroventrally, X-type skull table, and sutures always visible between premaxilla and the rest of t he frontoethmoidal shield. Unique features of the new form include: co mplete lack of ventral or ventrolateral endoskeletal opening of the na sal cavity; extremely short sphenoidal region; presence of postorbital pillar flanking lateral cranial wall; supraorbital sensory canal not reaching anterior part of snout; median rostral toothed and taking par t in upper jaw margin; and lower jaw with five coronoids. This new for m probably represents a basal member of the clade that includes Powich thys, Youngolepis, Diabolepis and Dipnoi (=Dipnoiformes of Cloutier, 1 990). The unusual character combination raises interesting questions a bout the interrelationship of the Dipnomorpha (sensu Ahlberg, 1991) an d helps to illustrate the possible character transformation sequence o f the stem lineage of dipnoans.