Heterobranchus austriacus Thenius, 1952

Kovalchuk, Oleksandr & Ferraris, Carl J., 2016, Late Cenozoic catfishes of Southeastern Europe with inference to their taxonomy and palaeogeography, Palaeontologia Electronica 51 (9), pp. 1-17 : 2-3

† Heterobranchus austriacus Thenius, 1952

Figure 2.1 -10

1952 Heterobranchus austriacus sp. nov.; Thenius, abb. 3.

1954 Heterobranchus austriacus Thenius, 1952 ; Weinfurter, plate 6, figures 12-14.

2002 Heterobranchus austriacus Thenius, 1952 ; Böhme, plate 4, figures 1-3, 6.

Material. pectoral-fin spines – 34 left, 34 right

( NMNHU-P 33/570-637, Mykhailivka 2), 8 left, 12 right ( NMNHU-P 41/2891-2893, 2908-2924, Frunzovka 2), 5 left, 1 right ( NMNHU-P 41/3459- 3464, Palievo), 2 left ( NMNHU-P 41/3563-3564, Otradovo), 4 right ( NMNHU-P 41/3731-3734, Kubanka 2), 1 left, 1 right ( NMNHU-P 41/3412- 3413, Novoelizavetovka 2).

Description. Slender pectoral -fin spine ( Figure 2.1, 2.4, 2.6 ) is slightly curved posteriorly. There are numerous blunt denticulations along the postaxial margin of the shaft. The regular denticulations are weak and directed perpendicular to the shaft. The anterior margin of the shaft has small rounded (tear-shaped) denticulations ( Figure 2.1, 2.6, 2.9 ). A well-developed shallow groove is situated proximally along the posterior margin of the shaft ( Figure 2.2 ). Edges of the pectoral-fin spine are narrow and laterally compressed; therefore the shaft is lenticular in cross-section. The broad cleithral surface ( Figure 2.3, 2.5, 2.7, 2.10 ) is crescent-shaped with numerous frequent ridges, which are characteristic of the genus Heterobranchus ( Böhme, 2002) . The three processes are designated as dorsal, ventral and anterior ( Diogo et al., 2001) or dorsolateral, ventrolateral and axial ( Otero and Gayet, 2001), respectively. The ventrolateral3 process is large, with a proximally directed rounded tip; the dorsolateral process is medium-sized and the axial process is smooth. A right pectoral-fin spine with an abnormal accrete intravital fracture ( Figure 2.8 ) was obtained from the Mykhailivka 2 locality.

Remarks. The pectoral-fin spines are similar in overall morphology and size to those identified as Heterobranchus austriacus from the Vösendorf- Brunn and Sandberg in Austria ( Gaudant, 1994; Böhme, 2002). However, pectoral-fin spines from the late Miocene of Ukraine have a larger ventrolateral process and more regular denticulations at the postaxial margin.

Figures

FIGURE 2. Isolated bones assigned to †Heterobranchus austriacus Thenius, 1952. 1-3, left pectoral-fin spine (NMNHU-P 33/570, Mykhailivka 2): dorsal view (1), ventral view (2), proximal articulation surface (3). 4-5, right pectoral-fin spine (NMNHU-P 41/3732, Kubanka 2): dorsal view (4), proximal articulation surface (5). 6-7, right pectoral-fin spine (NMNHU-P 41/2891, Frunzovka 2): dorsal view (6), proximal articulation surface (7). 8, right pectoral-fin spine with wrong accrete fracture (NMNHU-P 33/574, Mykhailivka 2), lateral view. 9-10, right pectoral-fin spine (NMNHU-P 41/2908, Frunzovka 2): lateral view (9), proximal articulation surface (10). Scale bars equal 5 mm (Figure 2.1-2, 2.4, 2.6, 2.8-9) and 2 mm (Figure 2.3, 2.5, 2.7, 2.10).