Rivista Italiana di Paleontologia e Stratigrafia volume 104 numero 3 15 Dicembre 1998 NOA BREVry . SHORT NOTE CTENOGNATHICHTHYS BELLOTTII (DE ALESSANDRI, 1910): NOMENCLATURAL PROBLEMS AND STRATIGRAPHICAL IMPORTANCE OF THIS MIDDLE TRIASSIC ACTINOPTERYGIAN FISH ANDREA TiNTORI* Receioed February 6, 1998; accepted September 2, 1998 Key-uords: Middle Triassic, paleopterygians, nomenclature, ho- lotype, neotype, stratigraphy. Riassunto. Durante la revisione della collezione paleontologìca depositata presso il Liceo Gìnnasio 'A.Volta' di Como, è stato rinve- nuto l'esemplare figurato da De Alessandri (1910) come esemplare ti- pico della sua nuova specre HeteroLepidotus (?) bellottii. Ciò solleva una questione nomenclaturale, poìchè, considerando perso i1 materia- ìe originario, è srato recentemente istituito un neotipo in seguito all'attribuzione di questa specie al nuovo genere Ctenognathichtlrys (Bùrgin, 1992). Seguendo il Codice Internazionale di Nomenclatura Zoologica, la questione è stata sottoposta alla Commissione Interna- zionale di Nomenclatura Zoologica. Poichè alcuni requisiti necessari per I'erezione di un neotipo non sono stati soddisfatti, l'olotipo deve essere considerato a tutti gli effetti come l'esemplare portatore del nome. Viene inoltre messa in evidenza I'importanza stratigrafica di questa specie presente sia nella Formazione di Perledo-Varenna (mate- riale originario) che nella Formazione di Besano (Scisti Ittiolitici di Besano o Grenzbitumenzone Auct.). Questo conferma che la fauna di Perledo, generalmente considerata un tutt'uno, è in realtà composta da almeno tre diverse associazioni di fossili avendo alcune specie (probabilmente 3) in comune con la fauna della Formazione di Besa- no e del1a parte inferiore del Calcare di Meride (Ladinico inferiore) e aimeno cinque specie in comune con la fauna della Kalkschìeferzone (membro sommitale del Calcare di Meride, Ladinico sommitale) rin- venuta à Ca' del Frate piggiù, Varese, Italia) e nei pressi di Meride (Tr cF . Abstract. The existence of one of the origìnal specimens of Ctenognatbicbtlrys bellottii (De Alessandri 1910), figured and labelled as 'type specimen' by De Alessandri himself, raises a nomenclaturaì question as there is also a neotype designated by Bùrgin (1992). The International Commission of Zoological Nomenclature has been as- ked to rule on the validity of the neotype. As some of the require- ments for the designation of a neotype were not met, the holotype should be treated as the name-bearing type. The discovery of this species in both the Besano Formation (Grenzbitumenzone Auct ) and the Perledo-Varenna Formation is very imPortànt lrom a stratr- graphic point of view, confirming that the so called Perledo fish-fau- na is composed of different assemblages. In fact, the Perledo fauna has most species in common with the Ca' de1 Frate (Viggiù, Varese, Italy) fauna from the Kalkschieferzone (uppermost Meride Lime- stone), which is latest Ladinian in age, while a few of the Perledo species have been found also in the Grenzbitumenzone and/or in the low-er Meride Lìmestone o{ Lower Ladinian age. lntroduction. During the revision of the paleontological coliec- tion stored in the Liceo Ginnasio 'A.Volta' school in Como (Italy), I was charged by the Archeological Sur- vey of Iombardy with the Triassic vertebrates. This small collection consists of twenty specimens, mainly found in the quarries around Perledo (Lecco, northern Italy). This material proved to be very important becau- se, like almost all the other specimens known from Per- ledo, it s/as collected in the first half of the last century and was used by De Alessandri (1910) for his mono- graph on the Triassic fishes from lombardy. Since then, very fe'w specimens have been collected and, in any case) nobody has ever described them. Furthermore, the Mu- seo Civico of Milano, which housed the main collec- tion, was destroyed during the Second World War, so that few of the described specimens have survived, the ones stored in the Senckenberg Museum in Frankfurt and in the Italian Geological Survey in Rome, other than those in Como. The reason why almost all Perledo vertebrates have been found during the last century is still unknown. Quarry.work, in fact, was carried on until 40 years ago, but new paleontological finds were limited to a few remains of Sawricbthys and Lariosaurus, whlle some other specimens have been collected by the author during field surveys. As for many other old collections, the exact strati- graphic position of the fossils inside the Periedo-Varenna Formation is not known; this is particularly regrettable since the unit is about 600 m thick (Gaetani et al., 1992). Nonetheless, comparison with the other Middle Triassic faunas recovered not far from Perledo (the Kalkschieferzone from Ca' del Frate (Viggiù, VA, Italy) and Meride (TI, CH) and the Besano-Monte S.Giorgio 'r Tlinarìmenrn ,l; qcienze della Terra, Università degli studi di Milano, Via Mangiagalli 34,Lz)fi3 Milano (Italia). e-mail: Andrea.Tinto- ri@unimi.it A. Tintori fauna) helps us in the srratigraphic definition of the per- ledo fossils" The lack of a complere modern revision of the Perledo fishes can be easily ascribed to the shortage of new material, giving even grearer importance to histori- cal collections. Bùrgin (1992) erected the new genus Ctenognatbi- chthys, to which he assigned a few Grenzbitumenzone specimens of the species Ctenognathichtlrys bellottii, orí- ginally described on Perledo marerial as Heterolepidorus (?) bellottii by De Alessandri (1910). Bùrgin (1992, p.78) designated also a neotype for this species, assuming the original specimens to be lost. Actually, the type speci- men still exists in the collection of the Liceo Ginnasio 'A.Volta' in Como, where it has been housed for at least 60 years (Fig. t). The type specimen ot Ctenognathichthys bellotti (De Alessandri, 191 0). Bùrgin (1992, p. Z8), describing the new genus Ctenognathichthys, wrofe "The holotype .was said to be located at the Museo Civico di Como, Italy (De Ales- sandri: 111). However, an intensive search failed to loca- te this specimen (G. Achermann, pers. comm.). Thus, it is necessary to designate a neotype. The neotype has been chosen from the Tessin collection and represents an almost complete specimen (PIMUZ T.4349) lrom Point 902 (layer 165), preserved in lateral aspect (Figs. 83 & 84)". Actually, I was also asked to help in locating the type specimen. At the time I did not know rhe exacr composition of the Como school collection, so I gave Bùrgin (phone comm.) the address and phone number of the Liceo Ginnasio 'A.Volta'. On the other hand, G. Achermann, a Swiss reporrer living in Italy, apparently never asked the Director of the Museo Civico di Como about the Perledo marerial (L Castelletti, wrirten comm.). Thus, neither was the director of the Museo Civico di Como directly inquired about the Perledo ma- Fig. 1 - Ctenognathichtlrys beLlottii (De Alessandri 1910): the holotype from Perledo, stored et the Liceo Ginnasro Statale 'A.Volta', Como, Italy (cata- logue n. 96"3890.10623). Spe- cimen dusted with ammo- nium chloride. Scale bar - 20 mm^ terial, norwas my suggestion foilowed. Therefore, Bùrgin's reasons for believing the holo- type to be lost are very weak (ICZN 1985, art. 75 d(3)). Furt- hermore, the designation of a neotype is not compulsory (ICZN 1.985, art" 75a); rn this case it was not necessary because no "exceptional circumstances" (ICZN 1985, art. Zsb(il) exrsted, Cteno- gnathichtbys bellotti being the only species ascribed to the genus, with no possibility of being confused with similar species. In addition, other rules were not fulfil- led by Bùrgin (1992) in erecting the neotype, especially regarding its locality and supposed age. It comes, in facr, from the Grenzbitumenzone of Monre S.Giorgio, whose stratigraphic and geographic positions are remarkably different from those of the type specimen (iCZN 1985, art. zsd(s)). Thus, in my opinion, even assuming the type spe- cimen to be 1ost, there was no need to designate a neo- type. F{owever, as rhe ICZN (1985, art. Z5h) states that similar cases must be referred ro rhe Commission, I submitted the question ro the International Commission on Zoological Nomenclature. Finally, as some of the re- quirements for the designation of a neotype were not met, the holotype should be treated as the name-bearing type without any further Commission pronouncement (P. Tubbs, written comm.). By the way, in that same paper (Búrgin, 1992), erecting the new species Peltoplewrws nothocephalus, Búrgin (1992, p. 123) gave the correcr etymology of the specific name, bur then used Peltopleurus notbosomoides throughout the description as well as in the caprions (but see Bùrgin, 1992, pag. 5 and 155). That the two names referred to the same species is proved by the ho- lotype (PIMUZ 7.2902) which is figured as peltopleurus nothosomoides (Bùrgin, 1992, fíg. 148) after having been cited as Pehopleurus notbocephalu.s. As Bùrgin himself agrees (written comm.), I consider Pebopleurus notboce- phalus as the valid specific name, for which the etymo- logy has been given, under the ICZN (1985, art. 24). The specific name Peltopleurus nothosomoides must rhen be considered a junior synonym. The original marerial of Ctenognathichtl4ts bellottii stored in Como consists of a complete specimen, though the body and the posterior half of the skull are preserved as counterparts. Glued to the specimen was a hand-written label (Fig. 2), most probably by De Ales- sandri himself, as all the specimens he cited in his work (De Alessandri, 1910) bear similar labels. Being on the underside of the specimen, the label is somewhat worn, but still legible: 'Esempl(are) tipi(co)': type specimen. Also the locality 'Perledo' is clear, even if De Alessandri wrote (1910) that the specimen was without previous 1a- bel, but being together with the other Perledo speci- mens and in rock of the same lithology it could well have come from the Perledo area. I agree with his inter- pretation because its preservation is that peculiar to the Perledo fishes. In De Alessanciri's (1910) picture this specimen appeared incomplete (see also Bùrgin, 1992) because the head remained unprepared and covered by a thin laver of matrix. I have prepared the hidden region, but, as in most of the Perledo material, the scarce bone preserva- tion makes the boundaries of the individual bones very uncertain. The large tooth-bearing bones are detectable and the peculilr teeth. which gave lhe name to this genus, are also distinctly visible. The broad frontals and the other dermal bones of the sku1l roof cannot be traced in detail, but they seem very close to the restoration made by Biirgin (1992). The opercular is more rectanguiar th.rn in Bùrgin's restoration, and its size is comparable to that of the subopercular. IJnfortunately, the preoper- cular region is disturbed and its peculiar shape cannot be detected. Squamation is composed of +l-++ transverse rows, each with 18 scales (respectively about 45 and 20 in the Grenzbitumenzofle specimens). Trunk scales are rectan- gular, and higher than long except in the six most ven- tral elements of each row, where scales become suddenly 419 Fig. 2 The original label. most pro- bably handwritten by De Alessandri, which was glued on the lower surface of the slab of the holotype of Cte- nognatbícbthys bellottù (De Alessanclri 1910). .r"r,, l^*, r h" l".oth hcino t qriee rhcir hciohr Tnwrrd rhe cludrl region, scales become gradually rhomhic. losinq the denticula- rion o[ the posterior edge thar is quite strong in the trunk re- gion. Also. the ornlmenretion of r he scrles v,lries wir h posi- tion on rhe body. Along the J^-^.1 ._ .-^:- :.. f-^rt oI theuvrùdr rrrdrÉllrr rll rrvl dorsal fin, dorsalmost scales are heavily ornamented with longi- tudinal ridges. Thinner ridges rre present .ill along the trunk region, being somewhat stronger in the ventrai part, iust above the low ridges" The small dorsai fin ori- ginates at the 31st scale-row, while the anal begins four rows in advance; both fins are very small. The caudal fin shows 6-7 epaxial rays. More than 30 segmented lepido- trichia are preserved and the central ones probably have been destroyed in the past during preliminary prepara- tion. The ventral lobe of the caudal fin, as well as the ana1, is preserved as impression: this kind of preserva- tion, with the extremities of the fish remaining on the counterpart, is comrnon Jmong the few known speci- mens from Perledo. After the preparation of and the new observations on the Como specimen, described and frgured by De Alessanclri (1910), its conspecificity with the ne.w mate- rial described by Btirgin (1,992) and its status as the ori- ginal type specimen of the type species of Ctenognatbt- chth^t,s is bevond anv doubt. Stratigraphic significance oî Ctenognathichthys bel- Iottii. Vhile very little interest has been payed recently to the Perledo vertebrate fauna. another famous Middle Triassic paleontologicai area, the Besano-Monte S. Gior- gio, h.rs seen r renell,rl of sttrdies, especiallv concerning fishes. The two localities are about 35 km apart from each other and both fossiliferous sequences span almost the whole Ladinian. They formed in the same sedimen- tary basin, but under different environmental condi- tions (Bernasconi, 1991; Tintori, 1.992; Bernascont ta Rrva, 1993; I-ombardo, 1,997, Tintori & Lombardo, in oress). C. belLottii holotype rediscoaery + 1\) MONTE SAN GIORGIO A. Tintori P. porroi, P. altolepis, A. nothosomoides, A. macroptera, F. trottii - Peltople u rus sP.n.A .--- r.._.-'T-ll:-#l - t:-ft-f:- Ff--T-i-rl r-r---T_---T-1 E l-r-----7r-t// // | @ t"ry t-v-;;71 r-r=-r=--] E;EITFFIl+ffi w=r-/--7---7- c o o, .E J Fig. 3 - Stratigraphy of the Besano-Monte S.Grorgio and the Perledo-Varenna area with correlation based on fishes present in both the sequences KSZ, Kalkschieferzonel' Pporroi, Prohalecites porroi; Paltolepis, Perleidus altolepis; A.notbosomoides, ÀLlolrpirtot6 nothoso- moi'd.es; A,macroptera, Aneurolepis macroptera: Etrottii, Furo trottii; C.bellottii, Ctenognathicht/rys bellottii; S.cortasquornàsus, Sauricbtlrys costdsqu+înosrts. Lithology: 1, sandy limestones; 2, marls; 3, thin bedded limestones, sometime larninated; 4, organic matter rich shales; 5, massive dolostones; 6, volcanic ashes; 7, biocalcarenitic limestones; 8, intrabasinal breccias; 9, thin bedded dolostones. Saurichthys macrocepnalus Upper Salvatore Dolomite Grenzbitu menzone -, C. bellottii , - ;'' Habroíchthys sp. S. cosfasquarnosus In the Besano-M.te S.Giorgio-Viggiù area, the site of Ca' del Frate (Viggiù-VA) has been exploited since the beginning of the 80s (Tintori et al., 1985; Tintori & Renesto, 1990; Tintori, 1990a,b). It is situated in the Kalkschieferzone, the upper member of the Meride Limestone (Senn, 1924). This member yields vertebrates from several levels (Bùrgin, 1995; Furrer, 1,995; Yirz, 1945; pers.obs.) across its 100 m of thickness; fish spe- cies, though, seem to have an uneven distribution, some of them being very common throughout the unit, and others being represented by single or raîe specimens. Lombardo (1997) descrlbes 15 species from Ca' del Fra- te, while in different levels in rhe area of Meride only a few species have been found, some so far unknown from Ca' dei Frate (Tintori et a1., in press). After the 1996-97 field seasons in Ca' del Frate and Meride, the recovered fish specimens number more than 3,000, of which at Ieast 95o/o belong to the small species Probaleci- tes porroi and fewer than 5o/o have been collected around Meride. A few fish species are common to Perledo and Ca' del Frate: Prohalecites porroi, Perleidus altolepis, Allolepi- dotus bellotti, Peltopleurus sp. n. A, Aneurolepis macropte- ra aîd Fwro trottii. Other species found in the Perledo area are unknown in the Kalkschieferzone, but have been found in the older vertebrate levels of the Monte S.Giorgio area (Fig. 3). For instance, aparf from a detached mandible (Tintori et. al, in press) and a Iarge skull recently found PERLEDO -VARENNA AREA Lierna Formation Perledo Member Esino Formation in the lower Kalkschieferzone near Meride, Saurtchtlrys seems to be absent in the middle Kalkschieferzone fossi- liferous level of Ca' del Frate. This fact led Tintori (1990b) to assume) for the first time, that the perledo fauna, where Saurichthys is well represented, embraces different fossil assemblages. Actually, Rieppel (1985), in his revision of the Middle Triassic Saurichtltys, observed that Saurichthys macrocephalus is presenr in both the per- ledo and the lower Meride Lm. faunas and that Sauri- chthys costasqua?nosus has been found in the Grenzbitu- menzone and the Perledo faunas, without discussing the stratigraphical implicar ions. Ascribing Grenzbitumenzone specimens ro rhe species CtenognathíchtLrys bellottií, which is not found above this level, Bùrgin (1992) fixther srrengrhened the simiiarity between the Grenzbitumenzone and part of the Perledo faunas, to which belongs the original speci- men described by De Alessandri (1910). The fact that Saurichtlrys costasquamosus and Cte- nognathcbtlrys bellottii are found in the Perledo-Varenna Formation, and are yielded also by the earliest Ladinian beds of the Grenzbitumenzone, seems ro contradict the age of the base of the former unit, which is considered upper Early Ladinian on rhe basis of conodonts (Gaeta- ni et al., 1992). However, the actual age difference be- tween the two units yielding Saurichtlrys costasquamosus and Ctenognathichtlrys bellottii may be very small (A. Nicora, pers. comm). The fact that these two species are found also in the late Ear|y Ladinian suggesrs their di- T I N U) Yo o q) c J .T o) = C. bellottii bolotype rediscovery REFERENCES 421 stribution could cover a wider time-span than we pre- viously knevr. Actually, two species of Cnenognatbi- chthys, one very close to Cnenognathichtlrys bellottii, have been recently found in the Middle Ladinian Pro- santo Formation of Eastern Switzerland (Bùrgin, pers. comm.). The same can be hypothesized for other fishes of the Grenzbitumenzone: some factors, such as a chan- ge in the depositional environment in the Besano-Monte San Giorgio area, may have prevented their local preser- vation later in the Ladinian. We suggest that during the Lower Ladinian the required conditions for vertebrate fossilization ended in the area of Besano-Monte San Giorgio, while, with slightly different characteristics, they persisted in the Perledo-Vareflna area. Only in the latest Ladinian were both areas again suitable for preser- ving a significant vertebrate record: ar. fhaf time the Kalkschieferzone and the Perledo member yield a very similar fauna. The stratigraphic distribution of fish species or ge- nera will be more precisely known when all the species contained in the three major vertebrate levels of the lower Meride Limestone have been individuated (Furrer, 1995). 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