Identification of tenuis of four French Polynesian <i>Carapini</i> (Carapidae: Teleostei)

Four species of adult Carapini (Carapidae) occur on Polynesian coral reefs: Encheliophis gracilis, Carapus boraborensis, C. homei and C. mourlani. Samples collected in Rangiroa and Moorea allowed us to obtain different tenuis (larvae) during their settlement phases or directly inside their hosts. These were separated into four lots on the basis of a combination of pigmentation, meristic, morphological, dental and otolith (sagittae) features. Comparison of these characters with those of the adults allows, for the first time, taxonomic identification of these tenuis-stage larvae

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

Fishes 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

Commensal vs. parasitic relationship between Carapini fish and their hosts: some further insight through d13C and d15N measurements

In the Moorea Lagoon (French Polynesia), the pearlfish Carapus boraborensis, Carapus homei, Carapus mourlani and Encheliophis gracilis are generally found inside echinoderm hosts such as the holothurian Bohadschia argus and the starfish Culcita novaeguineae. At the end of their larval stage, these fish settle on the reef and directly enter their echinoderm host where they undergo an important metamorphosis. The aim of this study was to get further insight on the type of symbiosis (commensal vs. parasite) between these fish and their hosts. d15N and d13C measurements were determined in the tissues of invertebrate hosts (holothurians and starfish) and carapids (larvae, juveniles and adults). The obtained isotopic signatures reveal different kinds of associations: metamorphosing larvae, juveniles and adults of C. boraborensis and C. homei do not feed at all on host holothurian tissues, C. mourlani and its asterian host display a commensal relationship without any feeding association, while E. gracilis is likely to feed on the tissue of the holothurian

Distinctive Anatomical Features of the Branchial Basket in four Carapidae Species (Ophidiiformi, Paracanthopterygii)

The present study focuses on the branchial basket in four Carapidae species: Carapus acus , Encheliophis boraborensis , Encheliophis homei and Encheliophis gracilis . The aim is to highlight the skeletal and muscular features of the branchial basket, especially those that are believed to be related to their way of life and/or to be linked to the presence of primary sound-producing muscles. The space occupied by the primary sound-producing muscles between the neurocranium and the branchial basket gives rise to distinctive skeletal and muscular features. They prevent the 1st pharyngobranchials from becoming attached to the neurocranium in the normal way. These do not seem to play any role in the suspension of the upper pharyngeal jaws, as it is usually the case in teleosteans. The 1st epibranchials are separated from the 2nd pharyngobranchials. Ossified interarcual elements jointed to the 2nd pharyngobranchials and 1st epibranchials are found in the position usually occupied by the latter. The presence of primary sound-producing muscles gives rise to the need for the reorganisation of the musculature which is seen in particular with regards to the levatores branchiales. These are not found on the neurocranium but on the hyomandibular. The general skeletal and muscular data and the observations of the stomach contents suggest that the action of the branchial basket is restricted to carrying food in Carapus acus , Encheliophis boraborensis and Encheliophis homei , whereas it could also play a role in the work of cutting up soft food in Encheliophis gracilis