Evidence Supporting a Sister-Group Relationship between Clupeoidea and Engrauloidea (Clupeomorpha)
The suborder Clupeoidei, with about 350 species, includes almost all Recent species of the Clupeomorpha, but relationships among the three clupeoid superfamilies (Engrauloidea, Clupeoidea and Pristigasteroidea) remain unresolved to date. The Clupeoidea and Engrauloidea are herein hypothesized as sister groups on the basis of morphological evidence. Among the proposed characters, only the presence of cartilage chevrons at the tips of epicentrals was previously reported as a possible synapomorphy for the Clupeoidea + Engrauloidea. Two additional characters are herein proposed in support of this hypothesis: the posteriorly directed parapophyses of the second vertebra and the interzygapophysal articulation. Evidence counter to this proposed relationship is the common presence of the gongyloid cartilage in the branchial arches of Pristigasteroidea and Engrauloidea, a structure apparently previously unrecorded in the literature and whose homologies are discussed. Additional circumstantial evidence for the clade Clupeoidea + Engrauloidea are also discussed. The position of Pristigasteroidea as a basal group of Clupeoidei has potential implications for the currently accepted sister-group relationship between Clupeomorpha and Ostariophysi.Abstract
Anterior vertebrae and parapophyses of (A) Ilisha kampeni (MZUSP 62477), (B) Stolephorus indicus (MZUSP 63113), and (C) Alosa pseudoharengus (MZUSP 62471) in ventral view, showing orientation of parapophyses of second vertebra. Rib of the third vertebra not represented. Abbreviations: papv2, parapophyses of the second vertebra; v1–3, first, second, and third vertebrae. Scale bars: 1 mm
Posterior caudal vertebrae in lateral view (anterior facing left), showing interzygapophysal articulation in (A) Chirocentrus dorab (MZUSP 62467), (B) Dorosoma cepedianum (MZUSP 62481) and (C) Cetengraulis edentulus (MZUSP 11634). In all drawings, posteriormost vertebra shown is preural 2. Abbreviations: postz, postzygapophyses (only haemal series indicated); prez, prezygapophyses (only neural series indicated). Scale bars: 1 mm
Posterior caudal vertebrae in lateral view (anterior to left), showing condition of pre- and postzygapophyses in (A) Pristigaster cayana (MZUSP 7023) and (B) Denticeps clupeoides (MZUSP 62480). In all drawings, posteriormost vertebra shown is preural 2. Abbreviations: postz, postzygapophyses (only haemal series indicated); prez, prezygapophyses (only neural series indicated). Scale bars: 1 mm
Partial view of dorsal gill-arch skeleton in dorsal view (cartilage in solid black) in (A) Pellona harroweri (MZUSP 11238) and (B) Anchoviella lepidentostole (MZUSP 51826). Abbreviations: E1–2, first and second epibranchials; GO, gongyloid cartilage; I1–3, first, second, and third infrafaryngobranchials. Scale bars: 1 mm