Browsing by Author "Wirtz, Peter"
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- A new species of Corcyrogobius (Teleostei: Gobiidae) from Ile de Ngor, SenegalPublication . Kovacic, Marcelo; Wirtz, Peter; Schliewen, Ulrich K.Corcyrogobius pulcher sp. nov. is described from off Ile de Ngor. Dakar, Senegal. Corcyrogobius pulcher is distinguished from its two congeners by having the rear edge of the jaws ending posteriorly below mideye, second dorsal fin 1/9, pectoral fin rays 17, pelvic fins oval or truncated posteriorly, scales in lateral series 26-27, anterior oculoscapular head canal with pore beta, suborbital row b of sensory papillae anteriorly beginning below vertical of posterior edge of eye, dark vertical caudal bar, branchiostegal membrane without intense dark spot, cheek with two oblique whitish stripes, the first going from the eye downwards and forward to the posterior jaws, the second on the preopercular, alternating with brown oblique stripe going from behind the eye downwards and forward across the cheek. Furthermore, mitochondrial COI-barcoding data unambiguously support the species-level distinctiveness of the three Corcyrogobius species. A key to the species of Corcyrogobius is provided.
- Alarm reaction and absence of alarm reaction to simulated predation on conspecifics in two temperate sea urchin speciesPublication . Wirtz, Peter; Duarte, JoanaBody fluids released by prey can signal the presence of a nearby predator. Numerous aquatic organisms show alarm responses to body fluids of conspecifics (reviewed by Chivers & Smith 1998, and by Ferrari et al. 2010). For nine sea urchin species, an alarm response to the smell of crushed conspecifics or the smell of extracts of conspecifics has been shown (Snyder & Snyder 1970, Mann et al. 1984, Parker & Shulman 1986, Campbell et al. 2001, Hagen et al. 2002, Vadas & Elner 2003). Two sea urchin species also responded to extracts from other species of the same genus (Parker & Shulman 1986). The sea urchins either moved to nearby shelter or moved away from the direction of the extract. We tested the two common, temperate eastern Atlantic sea urchins Arbacia lixula and Sphaerechinus granularis for the presence of such alarm reactions to simulated predation on conspecifics. (Introduction)
- An updated checklist of the marine Decapoda of ascension Island, central Atlantic OceanPublication . De Grave, S.; Anker, A.; Dworschak, P. C.; Clark, P. F.; Wirtz, PeterThe decapod Crustacea from Ascension Island are reported upon on the basis of major expeditions undertaken during 2008 and 2012, including several minor additional collections made in other years. Two species, Gnathophyllum americanum and Corallianassa longiventris are new records for the island bringing the total known marine decapod fauna to 75 species, of which 11 are currently endemic to Ascension Island.
- Ascension Island shallow-water Zoantharia (Hexacorallia: Cnidaria) and their zooxanthellae (Symbiodinium)Publication . Reimer, James Davis; Lorion, Julien; Irei, Yuka; Hoeksema, Bert W.; Wirtz, PeterThis is the first report on the Zoantharia fauna (Cnidaria: Hexacorallia) of the isolated oceanic island of Ascension, southern Atlantic, where zoantharians are a dominant component of the shallow-water benthos. Specimens from two expeditions (1983, 2012) were examined regarding external morphology and molecular phylogeny using three DNA markers, which confirmed the presence of four zoantharian species: Palythoa caribaeorum; Palythoa aff. clavata; Parazoanthus swiftii; and Zoanthus sp. Two of these, Palythoa aff. clavata and Parazoanthus swiftii, were previously only known from the western Atlantic and Caribbean. Molecular examination of the zooxanthellae (=Symbiodinium spp.) of Palythoa specimens showed that they were in association with only one type, subclade C1.
- Cinetorhynchus gabonensis, a new species of hinge-beak shrimp (Crustacea: Decapoda: Rhynchocinetidae) from the eastern AtlanticPublication . Duris, Zdenek; Sobanova, Anna; Wirtz, PeterA new species of the rhynchocinetid genus Cinetorhynchus, C. gabonensis sp. n. from the Atlantic waters of Gabon, is described based on morphological and molecular comparisons and its distinctive colour pattern. This is the second known species of the genus in the eastern Atlantic, and the third species in the Atlantic as the whole. The new species is more closely related to the western Atlantic C. manningi, both having quadrispinose ambulatory dactyli (i.e. with unguis + 3 ventral spinules), but differs from the latter by the presence of an arthrobranch on the three anterior pereiopods (vs only on the first pereiopod in C. manningi). The branchial formula of the new species is consistent with most of the Indo-West Pacific congeners, and with the amphi-Atlantic C. rigens
- Cirripedia of MadeiraPublication . Wirtz, Peter; Araujo, Ricardo; Southward, Alan J.We give a list of Cirripedia from Madeira Island and nearby deep water, based on specimens in the collection of the Museu Municipal do Funchal (Historia Natural) (MMF), records mentioned in the literature, and recent collections. Tesseropora atlantica Newman and Ross, 1976 is recorded from Madeira for the first time. The Megabalanus of Madeira is M. azoricus. There are 20 genera containing 27 species, of which 22 occur in depths less than 200 m. Of these shallow water species, eight are wide-ranging oceanic forms that attach to other organisms or to floating objects, leaving just 13 truly benthic shallow water barnacles. This low diversity is probably a consequence of the distance from the continental coasts and the small area of the available habitat. No endemic species have been found.
- Comment on 'Island biogeography: patterns of marine shallow-water organisms' by Hachich et al., Journal of Biogeography (2015)Publication . Ávila, Sérgio P.; Cordeiro, Ricardo; Haroun, Ricardo; Wirtz, PeterIn a recent article, Hachich et al. ( 2015, Journal of Biogeography, 42, 1871-1882) studied the large-scale biogeographical patterns of the species-area, species-island age and species-isolation relationships associated with marine shallow-water groups ( reef fish, gastropods and seaweeds) from 11 Atlantic archipelagos. We here express our concerns regarding the data accuracy used to compute the different models that tested the null hypothesis of species richness being independent of the selected variables. In our commentary, we focus mainly on the use of out-of-date checklists of gastropod and seaweed species from different archipelagos, but we also point out inaccuracies in some island age estimates and explain our disagreement with the use of the 200 m depth limit for the shallow-water gastropods and seaweeds.
- Digging with 'hands': observations of food capture in the flying gurnard Dactylopterus volitans (Linnaeus, 1758)Publication . Davenport, John; Wirtz, PeterVideofilms of a foraging flying gurnard (Dactylopterus volitans) were collected at Itaipu, Niteroi, RJ, Brazil. Analysis revealed details of the use of anterior parts of the pectoral fins which act as digging 'hands' to access infaunal prey items that are subsequently captured by oral suction feeding. Each pectoral fin has two distinct sections articulated separately on the pectoral girdle. The digging 'anterior pectoral fin' mainly consists of segmented and flexible fin rays but has an anterior robust unsegmented ray that provides an edge to the 'hand', allowing penetration of the substratum. The huge 'posterior pectoral fins' are supported by unsegmented rays. Most digging episodes involved one 'hand' and consisted of 1-7 cycles of movement with frequencies 1.15-3.74 cycles s(-1). During a cycle, the 'hand' is moved forwards and medially above the substratum, then is twisted medially and simultaneously depressed so that the anterior unsegmented ray impacts and enters the substratum. The hand is then drawn backwards and laterally to disturb the substratum. To prevent upward pitching of the head during digging, the 'posterior pectoral fins' are both moved anteriorly and laterally to shift the centre of gravity forwards while the caudal and second dorsal fins continue to provide propulsive force.
- Diplecogaster tonstricula, a new species of cleaning clingfish (Teleostei: Gobiesocidae) from the Canary Islands and Senegal, eastern Atlantic Ocean, with a review of the Diplecogaster-ctenocrypta species-groupPublication . Fricke, Ronald; Wirtz, Peter; Brito, AlbertoThe Diplecogaster-ctenocrypta species-group is reviewed it comprises two species. The clingfish Diplecogaster ctenocrypta from the Canary Islands is redescribed. The new species Diplecogaster tonstricula, a facultative cleaner of other teleosts, is described on the basis of eight specimens and colour photos from Senegal and the Canary Islands, eastern Atlantic Ocean. The species is small, apparently not exceeding 23mm total length; it is characterised by having nine dorsal-fin rays, eight anal-fin rays, 24-25 pectoral-fin rays, 14-15 principal caudal-fin rays, 13-16 rakers on third gill arch, pelvic disc without lateral papillae in region A, disc region B with two rows of weak papillae, interorbital distance 4.1-4.6 in head length, distance between disc and anus 14-17% of SL, head and body with 10-13 narrow vertical brownish bars, cheek with a white ocellus surrounded by black, and with a small black spot in the middle. The new species is compared with other species of the genus; a key to the six known species of the eastern Atlantic, Mediterranean and Black Sea and South African genus Diplecogaster is presented. A checklist is provided for the species of Diplecogaster and their synonyms.
- Diversity of Saint Helena Island and zoogeography of zoantharians in the Atlantic Ocean: jigsaw falling into placePublication . Santos, Maria E. A.; Wirtz, Peter; Montenegro, Javier; Kise, Hiroki; Lopez, Cataixa; Brown, Judith; Reimer, James DavisDiversity surveys in isolated sites, such as oceanic islands, provide biogeographic data that can improve our analyses and knowledge of evolutionary processes in the oceans. Zoantharians (Cnidaria: Anthozoa) are common and widespread components of shallow-water reefs, but distributional analyses are scarce for this group. In this study, we collected Zoantharia specimens from around Saint Helena Island (STH) in the mid-Atlantic and identified species using external morphology and molecular data. Moreover, we compiled and analysed the most comprehensive distributional data for zoantharian species in the subtropical and tropical Atlantic Ocean to date. Our results show eight zoantharian species in STH, which includes seven new records for STH waters. Furthermore, all families and genera of the suborder Brachycnemina recorded are widespread in the Atlantic Ocean, including at least four amphi-Atlantic species. The Caribbean is the richness centre in the Atlantic Ocean for zoantharian species, a pattern similar to that observed for many other subtropical/tropical marine taxa. However, Zoantharia may have a lower endemism rate in some areas than other common reef animals, for example zooxanthellate scleractinian corals and reef fishes. Moreover, zoantharian species have a more extensive distribution than close-related taxa such as zooxanthellate scleractinian corals and hydrocorals in the Atlantic Ocean.