A high latitude Gondwanan species of the Late Devonian tristichopterid Hyneria (Osteichthyes: Sarcopterygii)

Abstract

We describe the largest bony fish in the Late Devonian (late Famennian) fossil assemblage from Waterloo Farm near Makhanda/Grahamstown, South Africa. It is a giant member of the extinct clade Tristichopteridae (Sarcopterygii: Tetrapodomorpha) and most closely resembles Hyneria lindae from the late Famennian Catskill Formation of Pennsylvania, USA. Notwithstanding the overall similarity, it can be distinguished from H. lindae on a number of morphological points and is accordingly described as a new species, H. udlezinye sp. nov. The preserved material comprises most of the dermal skull, lower jaw, gill cover and shoulder girdle. The cranial endoskeleton appears to have been unossified and is not preserved, apart from a fragment of the hyoid arch adhering to a subopercular, but the postcranial endoskeleton is represented by an ulnare, some semi-articulated neural spines, and the basal plate of a median fin. The discovery of H. udlezinye shows that Hyneria is a cosmopolitan genus extending into the high latitudes of Gondwana, not a Euramerican endemic. It supports the contention that the derived clade of giant tristichopterids, which alongside Hyneria includes such genera as Eusthenodon, Edenopteron and Mandageria, originated in Gondwana.

Second species ofEusthenodon(Tristichopteridae, Sarcopterygii) from the Upper Devonian (Famennian) Catskill Formation of Pennsylvania, U.S.A., and a review of globalEusthenodonoccurrence

“…Hyneria ,” (Gess, 2011: p. 266), or suggested the taxon to be “close to Hyneria ” (Gess, 2011, p. 294; Gess & Clément, 2019, p. 2). Gess and Ahlberg (2022:p. 30), in a conference abstract, considered the assignment to Hyneria to be “confirmed.” Most recently, Gess and Ahlberg (2023) described Hyneria udlezinye from Waterloo Farm. The material that they referred to the new species includes some, though not all, of the specimens figured by Gess and Hiller (1995; AM4868, 5249, 5389, 5391) and additional specimens including a partial parietal shield (AM6535c, d), a partial postparietal shield (AM6540a), isolated cheek bones (AM6503a, 6526b, 6535b, 6541b, 18001), a partial lower jaw and isolated lower jaw bones (AM5668, 6502a, 18000a), dermal palatal bones (AM6508a, b; 6528a, b), operculogular/extrascapular bones (AM5532, 5888, 6542b, 6521a), pectoral girdle bones (AM6516a, b; 6528a; 6540b; 6545; 18003), axial and fin bones (AM18002), and lepidotrichia and scales (AM6533b, 6540, 18004).…”