Volume 23, Issue 2 – 28 April 2017
Volume 23, Issue 2 – 28 April 2017
New Scientific publication – started delivery on April 28, 2017
Ivan Sazima: Deception, protection, and aggression in the mangrove: three juvenile fishes and floating leaves in Southeast Brazil, pp. 41-46
Mangroves and similar habitats generally harbour rich and varied fish assemblages composed mostly of juvenile individuals (nurseries). I report here on juveniles of three fish species that make use of floating leaves in mangroves, tidal creeks, and beaches with freshwater influence. The tripletail Lobotes surinamensis uses leaves as a form of masquerade (resemblance to decaying leaves) both as protection against potential predators and as disguise to approach prey (aggressive mimicry). The mullet Mugil liza uses leaves as shelter against potential predators. The leatherjacket Oligoplites saurus uses leaves mostly as cover to approach its prey. These three fish species illustrate the variety of opportunities to use floating leaves in mangrovelike habitats. No doubt there are additional uses, but the majority of them would likely be a way to elude potential predators in one of the most vulnerable life stages of a fish.
A tripletail (Lobotes surinamensis) juvenile lies on its right side, hovering near a decaying leaf that floats at the water surface in the shallow portion of a beach under freshwater influence. Note the overall similarity of shape and colour of the fish and a leaf. Standard length 41.6 mm (ZUEC 892), 29 March 1983. Photo by I. Sazima.
João Paulo Krajewski, Roberta M. Bonaldo and Ivan Sazima: Do cleaner wrasses rub on reef manta rays to remove their own parasites?, pp. 47-53
Cleaner wrasses of the genus Labroides are the epitome of a cleaner fish. Herein we describe two cleaner wrasse species, Labroides bicolor and Labroides dimidiatus, displaying a behaviour known as chafing or flashing. When chafing, a fish rubs itself against sandy bottoms, rocks, vessels, or other rough surfaces including sea turtles and sharks. We recorded the two cleaner wrasse species rubbing themselves against the rough skin of reef manta rays, Manta alfredi, on a coral reef cleaning station at Yap, Micronesia, western Pacific. As chafing is a way to relieve skin irritation and an alternative to reduce external parasites, we suggest that these specialised wrasse species use this behaviour to remove their own ectoparasites when other cleaning services are unavailable. The recorded ray-wrasse cleaning association is noteworthy, since the rays provide food and cleaning opportunity to the wrasses at the same time.
A reef manta ray, Manta alfredi, passes slowly above a cleaning station held by two cleaner wrasse species, Labroides bicolor and L. dimidiatus. Note a L. bicolor individual (foreground) partly hidden by the first right gill slit of the ray. Photo by J. P. Krajewski.
Book review: The teeth of non-mammalian vertebrates by B. Berkovitz & P. Shellis, p. 54
Dalton Tavares Bressane Nielsen: Description of two new species of the Melanorivulus zygonectes
species group (Cyprinodontiformes: Cynolebiidae) from Rio Xingu and Rio Tapajós basins, Brazil, pp. 55-67
Two new species of the genus Melanorivulus are described, both belonging to the Melanorivulus zygonectes species group. Melanorivulus canesi n.sp. is found at a tributary of the middle Rio Xingu basin, Pará, state of Brazil. It differs from the other species of the Melanorivulus zygonectes species group by its color pattern, with males presenting metallic green color at body sides. Melanorivulus britzkei n.sp. is found at a tributary of the right bank in the middle Rio Tapajós basin, Pará state, Brazil. It differs from the other species of the Melanorivulus zygonectes species group by males presenting a yellow metallic color pattern in the head and by a white pelvic fin. A key to the species belonging to the Melanorivulus zygonectes species group is presented.
Melanorivulus britzkei, MZUSP 121646, holotype, male, 31.0 mm SL, in life (photo reversed). Photo by W. M. Ohara.
News: Aphanius sp., pp. 68-72