Bothus parvulus ( Gorjanović-Kramberger, 1884 )

Gol’din, Pavel, Haiduc, Bogdan Stelian, Kovalchuk, Oleksandr, Górka, Marcin, Otryazhyi, Pavlo, Brânzilă, Mihai, Păun, Elena Ionela, Barkaszi, Zoltán, Ţibuleac, Paul & Răţoi, Bogdan Gabriel, 2020, The Volhynian (late Middle Miocene) marine fishes and mammals as proxies for the onset of the Eastern Paratethys re-colonisation by vertebrate fauna, Palaeontologia Electronica (a 43) 23 (3), pp. 1-20 : 8

Bothus parvulus ( Gorjanović-Kramberger, 1884)

Figure 3I

1970 Caprovesposus sp. ; Macarovici, pl. 1, fig. 4.

Material and locality. Incomplete skeleton; Româneşti.

Description. An incomplete body of a sinistral flatfish (SL ca. 16.5 mm) with a reduced and partly broken caudal peduncle. The body is oval, 7.6 mm wide. The head is deep (5.9 mm or 128% head length) and relatively short (4.6 mm; 28% SL). The skull is asymmetrical, and its neurocranial part is roughly triangular. The small mouth (ca. 5% SL) is oblique, directed 60° to central body axis. The opercle is large and ovoid, and the preopercle is slender and boomerang-shaped. The preserved vertebral column is composed of 35 subrectangular vertebrae, including 10 abdominal and roughly 25 caudal ones. This assumption is based on the length of a vertebra and the total length of the vertebral column. The neural spines are long, and a few anterior abdominal spines bear conspicuous kinks at the bases. Imprints of myorhabdoi are visible at the distal tips of neural and haemal spines. Anterior pterygiophores of the dorsal fin are hourglass shaped. There are 17 principal rays in the caudal fin. The number of rays in other fins is unknown because of incompleteness of the specimen.

Comparison. The specimen described is almost identical to those of Bothus parvulus from the Sarmatian s.s. beds of Dolje ( Croatia) in size, body and head proportions ( Schwarzhans et al., 2017d, fig. 3, table 2), and in the total number of vertebrae. This specimen differs from the Middle Miocene Bothus sp. from the North Caucasus ( Carnevale et al., 2006) in having a larger size, a greater number of precaudal vertebrae, a shorter and deeper head, in the shape of the preopercle, and in the structure of anterior neural spine bases.

Remarks. The specimen is assigned to Pleuronectoidei based on body shape, asymmetrical skull and the dorsal fin extension over the orbital region ( Chapleau, 1993; Carnevale et al., 2006). The presence of myorhabdoi and 17 rays in the caudal fin are diagnostic for Bothidae ( Hensley, 1977; Hensley and Ahlstrom, 1984; Carnevale et al., 2006; Schwarzhans et al., 2017d). Relationships between separate taxa within this family based on osteological characters remain not completely resolved ( Chapleau, 1993; Chanet and Schultz, 1994). However, the shape of anterior dorsal fin pterygiophores and their insertion into cavities of the supraoccipital crest and the presence of robust rectangular haemal spines ( Chanet and Sorbini, 2001; Carnevale et al., 2006) support its assignment to the genus Bothus . A boomerang-shaped preopercle and a kink at the base of anterior neural spines of the dorsal fin ( Schwarzhans et al., 2017d) indicate that it is Bothus parvulus .

Figures

FIGURE 3. Fish remains from the Volhynian beds of Romania and Ukraine: A-B – Sarmatella doljeana (Kramberger, 1884), anterior part of the body (A), and caudal part (B), Leucuşeşti; C – Clupeinae gen. et sp. indet., isolated scale, Voineşti; D-E – Scombroidei indet., caudal part (D), Erbiceni, and middle part of the body (E), Aroneanu; F – Sparus brusinai (Kramberger, 1882), skeleton, Hrushivtsi; G-H – Sparus cf. brusinai (Kramberger, 1882), right dentary in lateral (G) and dorsal view (H), Pârâul lui Gheorghe; I – Bothus parvulus (Kramberger, 1883), body imprint, Româneşti. Scale bars equal 2 mm in C, 5 mm in A-B, D-E, G-I, and 2 cm in F.