The earliest endosymbiotic mineralized tubeworms from the Silurian of Podolia, Ukraine

Abstract

The earliest endosymbiotic tubeworms have been discovered within skeletons of the tabulate coralHeliolitessp. from the Silurian (Ludlow) of Podolia, Ukraine. The new tubeworm species has a maximum diameter about 1 mm, a slightly conical tube, a smooth lumen in the tube and a lamellar wall structure. The tube wall is 0.05-0.10 mm thick. The new endosymbiotic tubewormCoralloconchus bragensisn. gen. and sp. shares zoological affinities with the tentaculitids (incertae sedis) and is assigned to the Family Cornulitidae (Tentaculita, Cornulitida).

Calcareous tubeworms of the Phanerozoic

“…However, if we add Palaeozoic tubeworms of lophophorate affinities to this record, the shelly faunas of the Palaeozoic era may have been even more dominated by lophophorates than previously thought. The diversity of Palaeozoic problematic tubeworms was highest in the Silurian and Devonian (Bouček 1964;Richards 1974;Larsson 1979;Vinn 2004Vinn , 2005aVinn , 2006aTaylor & Wilson 2008;Vinn & Mõtus 2008) and decreased markedly in the Carboniferous. Hitherto reported shell repair indicates attempted predation on the problematic tubeworms in the Late Ordovician (Vinn 2009a), Silurian (Larsson 1979;Vinn & Mutvei 2005;Vinn & Isakar 2007;Vinn 2009a), and Devonian (Wilson & Taylor 2006).…”

“…They share affinities with tentaculitids (Weedon 1991(Weedon , 1994) and more generally with lophophorates (Taylor & Vinn 2006). The other common Palaeozoic tubewormlike calcitic problematica (tentaculitids, cornulitids, and trypanoporids) have often been affiliated with annelids, but are more recently transferred to lophophorates (Weedon 1990(Weedon , 1991(Weedon , 1994Vinn & Mutvei 2005;Vinn 2005aVinn , 2006bVinn & Isakar 2007;Vinn & Mõtus 2008). Some tubeworm-like Early Palaeozoic phosphatic fossils such as Sphenothallus (van Iten et al 1992) and the related hyolithelminth Torellella (Vinn 2006c) have been interpreted as cnidarians on the basis of their tube structure.…”

“…However, some of the Early Palaeozoic questionable polychaete worm borings in brachiopod shells could have been made by phoronids (Vinn 2005b). Enigmatic Palaeozoic tubicolous biomineralized tubeworms such as cornulitids (Vinn & Mutvei 2005;Vinn 2005a;Vinn & Mõtus 2008), microconchids (Taylor & Vinn 2006;Vinn 2006a, Vinn & Taylor 2007, Tymbochoos (Vinn 2006b), Anticalyptraea (Vinn & Isakar 2007), and tubicolous colonial hederelloids (Taylor & Wilson 2008), could represent calcifying phoronids or phoronid-related lophophorate worms.…”

The worm endosymbionts in tabulate corals from the Silurian of Podolia, Ukraine; pp. 185–192

“…4) in two coralla of Heliolites sp. (Vinn & Mõtus 2008). The infestation pattern of tabulate corals by C. sibiriensis is not random.…”

“…As a result of this interaction, a cavity is produced within the host skeleton in which the endosymbiont lives (Tapanila 2005). Three species of endosymbiotic worms, Chaetosalpinx ferganensis Sokolov, 1948, Chaetosalpinx sibiriensis Sokolov, 1948(= Camptosalpinx estonicus Klaamann, 1958, and Coralloconchus bragensis Vinn & Mõtus, 2008, are known in the Silurian tabulate corals of Baltica (Tapanila 2005;Vinn & Mõtus 2008). Chaetosalpinx sibiriensis has hitherto been reported from Parafavosites germana (Wenlock, NE Russia, Sokolov 1948) and Paleofavosites balticus (Llandovery, Estonia, Klaamann 1958).…”