ISSN 00329452, Journal of Ichthyology, 2013, Vol. 53, No. 9, pp. 687–701. © Pleiades Publishing, Ltd., 2013. Original Russian Text © E.M. Baykina, 2013, published in Voprosy Ikhtiologii, 2013, Vol. 53, No. 6, pp. 671–686. Diagnostic Importance of Visceral Skull Bones of Recent and Fossil Clupeinae (Pisces, Clupeidae) E. M. Baykina Moscow State University, Moscow, 119991 Russia email: [email protected] Received November 15, 2012 Abstract—An analysis of visceral skull bones morphology of six recent genera (Clupeonella, Sprattus, Clupea, Sardina, Sardinops, and Sardinella) and three fossil species (Illusionella tsurevica, I. pshekhensis, and Clupea doljeana) of Clupeinae was carried out. Description of bones of maxillary and opercular regions was done for examined taxa subject to generic and infra and interspecific variability. Due to ascertained features of vis cerocranium morphology of Illusionella species, we can distinguish them from all of the recent European clu peins. Also there is a number of generic features in this article which give us a possibility to distinguish either recent or fossil forms, even in case of separate paleoichhthyological material. DOI: 10.1134/S0032945213050019 Keywords: Pisces, Clupeinae, Illusionella, Clupea doljeana, visceral skull, generic features, Europe From Paleocene–Neogene deposits of Eastern cise drawings. Also rather valuable is the work of Phil Paratethys, a multitude of representatives of the sub lips (1942) dedicated to the osteology of one species of family Clupeinae are known. Most of them were dis the genus Sardinops—S. caerulea. However, typical of covered and described in the 19th–early 20th centu most descriptions is a situation when, in the diagnosis ries and are stored in museum funds of Europe under of this or another taxon, characters of different generic names Clupea and Alosa. In collections formed ranks—from subfamily to specific—appear. In addi from deposits of Ciscaucasia, there are also genera tion, the emphasis is on the structure of neurocranium Sardinella and Clupeonella rich in species composition of Clupeidae, while this information can be used with (Danil’chenko, 1980). Early researchers (Heckel, great limitations with respect to fossils. 1850; Kner, 1863; GorjanovicKramberger, 1884) The study performed demonstrated that visceral repeatedly noted that fossil Clupeidae are a very prob skull elements, namely big bones of the jaw apparatus lematic group since their diagnosis even up to species and opercular region clearly noticeable and recog is strongly hindered or impossible altogether. Similar nized on fossil material, even if it is separated, are far views are determined by the imperfection of the sys more informative for the systematic differentiation. tem of Clupeidae at the time and by specific features of On the basis of recent and fossil taxa, an attempt was proper fossil material. Its significance is affected by a made to order diagnostic characters of generic and multitude of facts: conditions of burial, the extent of specific ranks using the comparativeanatomical preservation and deformation, perspective of imprint method and the method of statistical analysis of cranio in a rock, etc. Thus, the primary assignment of Euro logical indices, as was, for instance, done in the paper pean fossil Clupeidae to the genera Clupea or Alosa of Vasil’eva (1996) for species of the genus Alosa (sub meant nothing but that this or that form should be family Alosinae). The unified system of characters will considered a herring. Many generic definitions of Clu permit comparison of fossil genera and species with peidae in collections of the 19th–early 20th centuries recent ones, as well as with each other, and obtainment are, as a rule, erroneous and should be revised. This of more precise definitions. This in turn will provide a can be aided by revealing diagnostic characters, pri possibility for a more efficient use of paleoichthyolog marily of the whole generic rank, used for both recent ical material, including fragmentary material, for pur and fossil Clupeinae. Craniological material can form poses of biostratigraphy. the basis for such work. The skull osteology of recent representatives of MATERIAL AND METHODS Clupeinae is known due to works of Matthews (1887), Smitt (1895), Ridewood (1904), Regan (1917), Phil Skulls of recent and fossil representatives of the lips (1942), Svetovidov (1952), Whitehead (1973, subfamily Clupeinae served as material for the study. 1985), and Grande (1985). Of special note is the work The study was made of 20 specimens of Clupeonella of Ridewood (1904) provided with anatomically pre cultriventris cultriventris, Sprattus sprattus balticus, 687 688 BAYKINA Clupea harengus (15 specimens of C. harengus haren addition, tilt angle (=deviation angle) of zygapophysis gus and 5 specimens of C. harengus membras), and (Amx)—angle between the axis of proper zygapophy Sardina pilchardus sardine; ten specimens of Sardi sis and the axis of the longitudinal bony rib of maxil nops melanostictus (after Whitehead et al., 1985); and lare—was determined. one specimen of Sardinella aurita (fixed in alcohol Supramaxillare posterior. For this sample from the collection 9318 of the sector of ich bone, three measurements were made and values of thyology of the Zoological Museum, Moscow State two indices were calculated: Lsmx—length of bone University). The fossil material includes: nine speci together with process; Hsmx—bone depth along its mens of Illusionella tsurevica Baykina (PIN dorsoventral axis; lsmx—length of process from the no. 5073—Konkian stage, northern vicinity of the vil anterior end of the bone to the point of bend of the sur lage of Tsurevskii, Pshekha River, Krasnodar krai), six face on the ventral side of the bone (Fig. 1b); Smx1— specimens of I. pschekhensis Baykina (PIN index of the length of process (ratio of the length of no. 5422—Sarmatian stage, 0.5 km northward the process of supramaxillare to Lsmx); Smx2—index of northern marginal area of the village of Tsurevskii, the bone body depth (ratio of the body depth and Pshekha River, Krasnodar krai), and six specimens of Lsmx). Clupea doljeana Kramberger (collection of D. Kram berger no. 27 “Sarmatian Fishes of Croatia and S u b o p e r c u l u m. Bone proportion was assessed Slavonia” from the Croatian Museum of Natural His from three measurements and two indices: Lsop— tory in the city of Zagreb—Sarmatian stage, localities maximum bone length along the craniocaudal axis; Dolye, Podsused, and Vranche, Croatia). Skulls of Hsop—maximum bone depth along the dorsoventral only adult fish were considered. axis; lsop—length of process along its axis from the dorsoventral end up to the point of bend at connection Recent material was processed by maceration of with the bone body on the posterior surface of subo salted heads in hot water, and fossil material was sub perculum (Fig. 1c); Sop1—index of the length of pro jected to mechanical preparation. In addition, for sev cess (ratio of the length of process and the bone eral samples of the genus Illusionella, the method of length); Sop2—index of the bone body depth (ratio of transfer of skeletal remains to epoxy resin was used to the bone body depth and its length). elucidate the details of skull structure. I n t e r o p e r c u l u m. For this bone, three mea For analysis, nine bones of visceral skull were cho surements were made and two indices were deter sen: maxillare, second supramaxillare, suboperculum, mined: Liop—bone length; Hiop—bone depth at its interoperculum, praeoperculum, operculum, last ray anterior end; H’iop—bone depth at posterior end of branchiostegal membrane, anguloarticulare, and (Fig. 1d); Iop —anterior index (ratio of interopercu dentale. These bones that are usually distinguishable 1 lum depth at anterior end to bone length); Iop2—pos on the skull of fossil forms also occur in an isolated terior index (ratio of interoperculum depth at poste form. In this case, taxon diagnosis becomes most dif rior end to bone length). ficult for the researcher. P r a e o p e r c u l u m. To assess habitus of this We provide methods of measuring bones and bone, six measurements were made because of its description of the system of indices accepted in the complicated form: Lpop—bone length from the ante given paper below. rior end of the bone to extreme point at posterior mar M a x i l l a r e. Bone sizes and proportions were gin along the axis via longitudinal crest of the horizon assessed according to three measurements and two tal branch; Hpop—bone depth from the dorsal end of indices: Lmx—bone length along the longitudinal axis the bone to the extreme point at ventral margin along without zygapophysis; Hmx—maximum bone depth the axis through the longitudinal crest of the vertical along its dorsoventral axis; lmx—length of zygapophysis branch; L’pop—length of horizontal branch from the from the extreme articular head until the point it interacts anterior end of the bone to the point of intersection with the longitudinal axis of maxillare (Fig. 1a); Mx1— with the longitudinal crest of the vertical branch; index of elongation of zygapophysis (ratio of zygapo H’pop—depth of vertical branch from the dorsal end physis length and the bone length); Mx2—index of of the bone to the point of intersection with the longi maxillare habitus (ratio of depth and bone length). In tudinal crest of the horizontal branch; lpop—length of Fig. 1. Schemes of main measurements of bones of visceral skull of representatives of Clupeinae: (a) maxillare (Lmx—length