A critical review of ontogenetic development in Terebellidae (Polychaeta)

Abstract

Garraffoni, A.R.S. and Lana, P.C. 2010. A critical review of ontogenetic development in Terebellidae (Polychaeta). -Acta Zoologica (Stockholm) 91: 390-401.This study reviews the ontogenetic variability of the head, the first segments and the uncini in Terebellidae, based on primary literature and development series of four terebellid species. We test hypotheses on character homologies and indicate informative characters for future phylogenetic analyses. The prostomium, identified as the region above the prototroch band of the larva, in addition to being the region of origin of the buccal tentacles, contains a series of nerves originating from the cerebrum. The peristomium, which contains the mouth, is innervated by the stomogastric nerve and consists of upper and lower lips and an internal pharynx. The loss of the first notochaetae and neurochaetae in the course of development is a recurrent pattern in terebellids. The claviform chaetae disappear with age and growth, and can be used to define the larval stage. Chaetogenesis shows that the long shaft-shaped manubrium and posterior process develop from different regions. The uncini terminology 'double rows' was reinterpreted and renamed 'inverted rows', which better reflects the inversion of chaetal positions during ontogenetic development.

Morphology of terebelliform polychaetes (Annelida: Polychaeta: Terebelliformia), with a focus on Terebellidae

“…However, all our interpretations and conclusions are based exclusively on the morphology of the adults and some need to be confirmed by developmental studies, especially with regard to the development of the prostomium, peristomium and anterior segments. A recent study on larval development of four species of Terebellinae (Garraffoni & Lana 2009) confirmed our interpretation on the anterior end of terebellids.…”

“…We believe that a major contribution to this poor state of knowledge is the confusion that exists in the literature with regard to the morphology of Terebelliformia, especially the anterior end, as also discussed by Garraffoni & Lana (2009). This is mainly due to the fact that authors have used different names for the same structures and often have not used the terms consistently over time, making it difficult to make comparisons and assess homologies between taxa (see Table 1 in Zhadan & Tzetlin [2002] and Garraffoni & Lana [2009]).…”

Spaghetti to a Tree: A Robust Phylogeny for Terebelliformia (Annelida) Based on Transcriptomes, Molecular and Morphological Data

“…Buccal tentacles. It is generally accepted that the tentacles of Terebellidae and Trichobranchidae are prostomial based on the morphology of the adult [26,63,77] and the larvae [78][79][80][81][82][83]. Homology of the terebellid and trichobranchid prostomial tentacles with the tentacles of Ampharetidae, Melinnidae and Pectinariidae is debated.…”

“…Even though the manubrium (handle, shaft) is not prolonged in this type, they are often described as "long-handled" or "long-shafted" [26], a term, which is also confusingly used for trichobranchid hooks (where the term is appropriate because the manubrium is elongated). Several authors have pointed out that these two types are not homologous, as only the posterior process, not the entire body of the uncinus, is elongated [25,26,77,109].…”

A redescription of Unobranchus (Annelida: Terebellida: Trichobranchidae), with notes on the systematics of Trichobranchidae

“…The main difference between the two families is that Trichobranchidae have thoracic neurochaetae with a long shaft and small terminal teeth above the main fang (except for the first chaetiger in Terebellides Sars, 1835, where the chaetae have a simpler structure), whereas the Terebellidae usually have uncini (small multi-toothed hooks with a short shaft) in this position (thoracic neurochaetae are absent in some Polycirrinae). The exact morphology has been discussed by Garraffoni and Lana (2010). Since 1917, the group has been treated as a subfamily (e.g.…”