Phylogenetic analysis of the pearlfish tribe Carapini (Pisces: Carapidae)

Abstract

 AbstractParmentier, E., Castillo, G., Chardon, M. and Pandewalle, P. 2000. Phylogenetic analysis of the pearlfish tribe Carapini (Pisces: Carapidae).-Acta Zoologica (Stockholm) 81 : 293 -306Fishes of the tribe Carapini ( Encheliophis and Carapus ) share a noteworthy peculiarity: they shelter in holothurian echinoderms or bivalve hosts. Some species are considered parasitic, others commensal. This study focuses on the phylogeny of the tribe, using two other Carapidae species as an outgroup ( Snyderidia canina and Onuxodon fowleri ). Insofar as possible, the selected anatomical and behavioural characters where chosen in an ecomorphological perspective, as features that could be responses to various lifestyle-related constraints. Our character selection also took into account the fact that some features are (presumably) linked. Such features were grouped together as a single trait to avoid their overvaluation.This methodology enabled commensals to be separated from parasites, the former belonging to Carapus and the latter to Encheliophis. Carapus species reflect in their morphology the constraints imposed by a diet of hard, mobile, elusive prey, showing predator-type features: a strong dentition, a wide mouth opening, a robust food intake apparatus. On the other hand, the endoparasitic Encheliophis species show a generally weaker buccal apparatus and narrow mouth opening, in relation to the different constraints of their lifestyle where the diet constraints are less pronounced: they eat body parts of their host. Changes in both generic diagnoses are proposed and three species are transferred from Encheliophis to Carapus.

Unique morphologies of Encheliophis vermiops (Carapidae) with revised diagnosis of the genus

“…Most of these characters are not useful because the Carapini species have overlapping meristic values, cardiform teeth and small teeth on the dentary (Markle and Olney 1990;Parmentier et al 2000). In this diagnosis, the presence of the adnate maxilla allows us only to ascertain that the specimens in this study belong to the Encheliophis (Parmentier et al 2000). As a result, the diagnosis of E. vermiops in Markle and Olney (1990) is not useful for recognising the species.…”

“…They also add: the posterior position of the maxilla is partly adnate; cardiform teeth are present on the premaxilla; enlarged fangs are absent; dentary and palatine bear tightly spaced triangular teeth, which appear to interdigitate; the swimbladder is short without a pseudochamber. Most of these characters are not useful because the Carapini species have overlapping meristic values, cardiform teeth and small teeth on the dentary (Markle and Olney 1990;Parmentier et al 2000). In this diagnosis, the presence of the adnate maxilla allows us only to ascertain that the specimens in this study belong to the Encheliophis (Parmentier et al 2000).…”

“…5245) and paratype (AMS IB. The cephalic morphology of the genus Encheliophis has been thoroughly described by Markle and Olney (1990) and by Parmentier et al (1998Parmentier et al ( , 2000. The sound-producing apparatus is described in detail in Parmentier et al (2003).…”

“…Several species that belong to the genera Onuxodon, Carapus and Encheliophis are well known for their unusual behaviour of entering and living inside invertebrate hosts such as species of the Holothuroidea, Asteroidea and Bivalvia (Arnold 1956;Trott 1981;Markle and Olney 1990). The species that belong to the genus Encheliophis are parasites of holothurians (Parmentier et al 2000;Parmentier and Das 2004). Encheliophis is diagnosed by 11 autapomorphies (Parmentier et al 2000), among which are two characters easily observable in the field: the maxillaries and premaxillaries are united by short connective fibres to function as a unit, and both elements are bound to the skin, preventing a large gape (Parmentier et al 1998).…”

“…The species that belong to the genus Encheliophis are parasites of holothurians (Parmentier et al 2000;Parmentier and Das 2004). Encheliophis is diagnosed by 11 autapomorphies (Parmentier et al 2000), among which are two characters easily observable in the field: the maxillaries and premaxillaries are united by short connective fibres to function as a unit, and both elements are bound to the skin, preventing a large gape (Parmentier et al 1998). Five Encheliophis are recognised: Encheliophis gracilis (Bleeker 1856), Encheliophis sagamianus (Tanaka 1908), Encheliophis vermiops Markle and Olney 1990, Encheliophis vermicularis Müller 1842, and Encheliophis chardewalli Parmentier 2004.…”