Ophioscion Gill, 1863

Chao, Ning Labbish, Carvalho-Filho, Alfredo & Santos, Jonas De Andrade, 2021, Five new species of Western Atlantic stardrums, Stellifer (Perciformes: Sciaenidae) with a key to Atlantic Stellifer species, Zootaxa 4991 (3), pp. 434-466 : 437

Genus Ophioscion Gill, 1863 as a junior synonym of Stellifer Oken, 1817

Gill (1863) designated the genus Ophioscion with the eastern Pacific species, O. typicus Gill, 1863 , as the type species, which was distinguished only from Bairdiella by having an oblong head, a narrow and prominent snout with a small, inferior mouth. The gas bladder of O. typicus has two chambers, as present in all stelliferines, but lacks appendages on the hind margin of the anterior chamber ( Fig. 1A , left). Chao (1978) distinguished the genus Ophioscion from Stellifer , by lacking a pair of variably developed appendages on the hind margin of the anterior chamber ( Fig. 1 ). Sasaki (1989) incorrectly assigned the tooth plate on pharyngobranchial 2, enlarged and anteriorly located, as an autapomorphic character of Ophioscion ; when in fact they share this derived condition with other closely related genera (e.g. Bairdiella ), and this should be considered a homoplasy. Additionally, Sasaki added the medially concave ventral margin of the palatine as an autapomorphy of Stellifer . Therefore, the morphological features separating the current Stellifer genus from other genera within Stelliferinae are the enlarged lapillus that is about the same size of the oval shaped sagittal otoliths ( Fig. 2 ) vs. shorter and triangular in Bairdiella , Corvula , Elattarchus and Odontoscion ( Fig. 3 ), and the vertebral counts of 10 abdominal and 15 caudal in Stellifer (Ophioscion) , vs. either 12+13 or 11+ 14 in other stelliferine genera ( Fig. 4 ). Recent molecular studies ( Santos et al. 2013; Barbosa et al. 2014; Lo et al. 2015; Silva et al. 2018) have confirmed that Stelliferinae is a monophyletic group, but the monophyly of Ophioscion and Stellifer are not supported. We agree with the suggestion of Silva et al. (2018) that Ophioscion is a junior synonym of Stellifer .

Figures

FIGURE 1. Two-chambered gas bladders of Stelliferinae, left & right halves represent different forms or taxa. A. left, Bairdiella, Corvula, Elattarchus, Odontoscion & Stellifer (Ophioscion); right, S. naso & S. venezuelae. B. left, S. microps, hatched area indicates drumming muscle patch; right, small knob-like such as S. griseus, S. colonensis, S. lanceolatus, etc. C. left, S. brasiliensis; right, S. rastrifer.

FIGURE 2. CT scan of the ventral region of the head of Stellifer collettei new species (paratype: MCZ 157278, 76.2 mm SL) showing the in situ positions of three pairs of otoliths; a large lapillus located anteriorly, a large triangular-shaped sagitta in the middle, and a thin asteriscus located post-laterally (CT Scan by Andrew Williston, MCZ, Harvard University).

FIGURE 3. Otoliths of Stelliferinae.A. Bairdiella chrysoura. B. Stellifer punctatissimus. C. Stellifer rastrifer. A, B, C, Sagitta: left image, lateral view with medial surface facing to the left; right image, medial surface view. A’, B’, C’, Lapillus: left image, lateral view with medial surface facing to the left; right image, medial surface view. a, b, c,Asteriscus: left image, lateral surface, right image, medial surface (otolith orientations follow in situ position in Fig. 2).

FIGURE 4. Stelliferinae vertebral columns with a total of 25 vertebrae (precaudal + caudal).A. Bairdiella (11+14); B. Corvula, Elattarchus & Odontoscion (12+13); C. Stellifer (10+15). a. indicates the first vertebrae; b. the first caudal vertebrae.