Patterns of morphological diversity among and within arcid bivalve species pairs separated by the Isthmus of Panama

2001 ◽  
Vol 75 (3) ◽  
pp. 590-606 ◽  
Author(s):  
Peter B. Marko ◽  
Jeremy B. C. Jackson
Keyword(s):  
Morphological Variation ◽  
Fossil Record ◽  
Eastern Pacific ◽  
Nominal Species ◽  
Western Atlantic ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
Recent Species ◽  
Discriminant Analyses ◽  
Collection Sites

Geminate species are morphologically similar sister-species found on either side of the Isthmus of Panama. The existence of all geminates in the tropical Eastern Pacific ocean and the Caribbean Sea is most often explained by vicariance: closure of the Central American Seaway 3.1 to 3.5 Ma simultaneously isolated populations of species with amphi-American distributions. In this paper, we test the potential of morphological measurements for discriminating between Recent geminate species pairs from three genera (Arca, Arcopsis, and Barbatia) in the bivalve family Arcidae and examine the prospects for distinguishing nominal species in the fossil record. Fourteen morphological variables were used to characterize shell shape and multivariate methods were used to discriminate between five Recent species pairs. Collection sites were also used as a priori groups for discrimination to describe patterns of intraspecific morphological variation and to evaluate differences among samples from different geographic regions.On average, 84 percent of specimens within geminate pairs are classified correctly following five separate discriminant analyses with nominal species as the grouping variable. Although all but one arcid species pair are discriminated with high statistical significance, some collection sites within species are highly morphologically distinct. Overall, a large proportion of specimens from each collection locality (79 percent on average) can be classified correctly to site although no single site possessed a multivariate centroid that was significantly different from all other conspecific centroids. The distinctiveness of some collection sites, however, raises the possibility that some nominal species may harbor cryptic species, indicating the need for wider geographic surveys of both molecular and morphological variation within geminate species pairs.The eigenvalue coefficients derived from the Recent samples of one geminate pair (Arca mutabilis and A. imbricata) were used to assess the potential for identifying arcid species in the fossil record. Discriminant analyses of fossil Arca indicate that the forms that characterize Recent A. mutabilis and A. imbricata are present in the fossil record as far back as the Late Early Miocene, in the Cantaure Formation of Venezuela. Because a deep water connection between the Eastern Pacific and Western Atlantic existed until the Middle Miocene, the morphological differences associated with Recent A. mutabilis and A. imbricata likely existed well before the rising Isthmus affected ocean circulation patterns in tropical America. Therefore, despite great overall morphological similarity, these putative geminate species likely have a time of divergence that is at least four times older than final seaway closure. The geographic distribution of fossils also suggests that morphological forms associated with each Recent species had amphi-American distributions both before and after isthmus formation but are now geographically restricted to either side of the isthmus in the Recent fauna.

Revision of the family Euryplacidae Stimpson, 1871 (Crustacea: Decapoda: Brachyura: Goneplacoidea)

Zootaxa ◽  
2010 ◽  
Vol 2375 (1) ◽  
pp. 1 ◽  
Author(s):  
PETER CASTRO ◽  
PETER K. L. NG
Keyword(s):  
Florida Keys ◽  
Eastern Pacific ◽  
Nominal Species ◽  
Pacific Region ◽  
Tropical Eastern Pacific ◽  
Atlantic Region ◽  
Western Atlantic ◽  
The Family ◽  
The World ◽  
Pacific Species

The family Euryplacidae Stimpson, 1871, traditionally included in the Goneplacidae MacLeay, 1838, is revised based on the examination of the type material of many of its species as well as unidentified and previously identified material from around the world. The revised family now consists of 31 species (including five that are described as new) belonging to 13 genera (including four that are described as new): Eucrate De Haan, 1835, with eight species, of which one is new; Euryplax Stimpson, 1859, with two species; Frevillea A. Milne-Edwards, 1880, with three species; Henicoplax n. gen., with five species of which three are new; Heteroplax Stimpson, 1858, monotypic; Machaerus Leach, 1818, with two species; Nancyplax Lemaitre, García-Gómez, von Sternberg & Campos, 2001, monotypic; Platyozius Borradaile, 1902, monotypic; Psopheticoides Sakai, 1969, monotypic; Systroplax n. gen., monotypic; Trissoplax n. gen., with two species, of which one is new; Trizocarcinus Rathbun, 1914, with two species; Villoplax n. gen., monotypic; and Xenocrate Ng & Castro, 2007, monotypic. The genus Platyozius and Eucrate formosensis Sakai, 1974, are removed from the synonymy of Eucrate and E. alcocki Serène, in Serène & Lohavanijaya, 1973, respectively. Neotypes are selected for Heteroplax dentata Stimpson, 1858, and Pilumnoplax sulcatifrons Stimpson, 1858, two species described from Hong Kong that have a confusing taxonomic history. A neotype is also selected for Euryplax nitida Stimpson, 1859, described from the Florida Keys. Seven nominal species described by other authors were found to be junior subjective synonyms for other species: Eucrate affinis Haswell, 1882, E. costata Yang & Sun 1979, E. haswelli Campbell 1969, and Pseudorhombila sulcatifrons var. australiensis Miers, 1884, of Trissoplax dentata (Stimpson, 1858); Galene laevimanus (Lucas, in Jacquinot & Lucas, 1853) of Eucrate dorsalis (White, 1849); Heteroplax nagasakiensis Sakai, 1934, of H. transversa Stimpson, 1858; and Pilumnoplax sulcatifrons Stimpson, 1858, of Eucrate crenata (De Haan, 1835). Eight euryplacid genera are exclusively found in the Indo-West Pacific region (except one species introduced in the Mediterranean), one is exclusive to each the Eastern Atlantic and Tropical Eastern Pacific regions, three to the Western Atlantic region, and one genus has both Western Atlantic and Tropical Eastern Pacific species.

scholarly journals Convergence, divergence, and parallelism in marine biodiversity trends: Integrating present-day and fossil data

2015 ◽  
Vol 112 (16) ◽  
pp. 4903-4908 ◽  
Author(s):  
Shan Huang ◽  
Kaustuv Roy ◽  
James W. Valentine ◽  
David Jablonski
Keyword(s):  
Fossil Record ◽  
Eastern Pacific ◽  
Marine Biodiversity ◽  
Western Atlantic ◽  
Geographic Ranges ◽  
Diversity Gradients ◽  
Marine Bivalves ◽  
Fossil Data ◽  
Warm Temperate

Paleontological data provide essential insights into the processes shaping the spatial distribution of present-day biodiversity. Here, we combine biogeographic data with the fossil record to investigate the roles of parallelism (similar diversities reached via changes from similar starting points), convergence (similar diversities reached from different starting points), and divergence in shaping the present-day latitudinal diversity gradients of marine bivalves along the two North American coasts. Although both faunas show the expected overall poleward decline in species richness, the trends differ between the coasts, and the discrepancies are not explained simply by present-day temperature differences. Instead, the fossil record indicates that both coasts have declined in overall diversity over the past 3 My, but the western Atlantic fauna suffered more severe Pliocene−Pleistocene extinction than did the eastern Pacific. Tropical western Atlantic diversity remains lower than the eastern Pacific, but warm temperate western Atlantic diversity recovered to exceed that of the temperate eastern Pacific, either through immigration or in situ origination. At the clade level, bivalve families shared by the two coasts followed a variety of paths toward today’s diversities. The drivers of these lineage-level differences remain unclear, but species with broad geographic ranges during the Pliocene were more likely than geographically restricted species to persist in the temperate zone, suggesting that past differences in geographic range sizes among clades may underlie between-coast contrasts. More detailed comparative work on regional extinction intensities and selectivities, and subsequent recoveries (by in situ speciation or immigration), is needed to better understand present-day diversity patterns and model future changes.

scholarly journals Revision of the ‘dragon-head’ cusk eels of the genus Porogadus (Teleostei: Ophidiidae), with description of eight new species and one new genus

Zootaxa ◽  
2021 ◽  
Vol 5029 (1) ◽  
pp. 1-96
Author(s):  
WERNER W. SCHWARZHANS ◽  
PETER R. MØLLER
Keyword(s):  
New Species ◽  
Sampling Bias ◽  
Eastern Pacific ◽  
Lateral Line System ◽  
Nominal Species ◽  
Line System ◽  
Discovery Research ◽  
Continental Slopes ◽  
Species Pairs ◽  
Being Moved

The ophidiid genus Porogadus occurs between 800 and 5300 m in the tropical and subtropical world oceans. Fifteen nominal species have been described since 1878 and most of them until 1902. The genus has been highlighted as needing revision in recent compilations about ophidiiforms and here we present the first comprehensive review. Twelve of the previously described species are here accepted as valid with two being moved to the newly established genus Tenuicephalus n. gen. that encompasses fishes differing from those of Porogadus in the extremely weak ossification, the stout head, absence of head spines and absence of the “triple” lateral line system considered typical for Porogadus and a reduced dentition. In addition, eight new species are described: Porogadus caboverdensis, P. dracocephalus, P. lacrimatus, P. mendax, P. solomonensis, P. turgidus, Tenuicephalus multitrabs and T. squamilabrus.                 The species of Porogadus show a distinctive depth segregation with the majority of species having a demersal bathyal life-style between 800 and 3500 m and other species being more or less exclusively restricted to abyssal depths below 3000 m. The biogeographic distribution pattern of bathyal groups shows putative species pairs in the Atlantic versus the eastern Pacific and a clear separation of eastern Pacific from Indo-West Pacific species. The geographic effects and timing are being discussed that may have led to this speciation events. Generally, we found widely distributed species that are found far away from continental masses and others restrained to continental slopes and sometimes exhibiting regionalism. In abyssal depth, the Cabo Verde and Canary basins off NW-Africa have yielded three exclusive species, but it is uncertain at this stage whether this could represent a sampling bias with this area being extensively sampled by the Discovery research vessel (BMNH) over the years from 1970–1998. Another instance of a potentially endemic abyssal species is that of Porogadus melanocephalus in the Bay of Bengal. The latter has been caught with 45 specimens in a single trawl, representing the highest number of Porogadus specimens collected in any trawl and indicating that these fishes may actually not be as rare as one might assume from the literature.  

Taxonomy and phylogeny of Armina (Gastropoda: Nudibranchia: Arminidae) from the Atlantic and eastern Pacific

2011 ◽  
Vol 91 (5) ◽  
pp. 1107-1121 ◽  
Author(s):  
Diana P. Báez ◽  
Néstor Ardila ◽  
Ángel Valdés ◽  
Arturo Acero P.
Keyword(s):  
Phylogenetic Analysis ◽  
Branch And Bound ◽  
Branch And Bound Algorithm ◽  
Eastern Pacific ◽  
Nominal Species ◽  
Western Atlantic

Armina is the most species-rich genus of the Arminidae family with over 50 nominal species. Material of the genus Armina from the western Atlantic and the eastern Pacific was revised. Six species have been documented from the western Atlantic; however, we have determined that only four of them are valid: Armina muelleri, A. wattla, A. juliana and A. elongata. Also, only three out of seven species previously registered in the eastern Pacific were recognized in the present study: A. californica, A. cordellensis and Armina sp., an unnamed species. The phylogenetic analysis of 13 taxa and 17 characters was performed using the program PAUP (Phylogenetic Analysis Using Parsimony). The Branch-and-Bound algorithm generated a 29-step tree with the following relations: (Histiomena convolvula, (Dermatobranchus sp., ((((A. californica , (A. maculata, A. muelleri)), ((A. loveni, A. neapolitana), A. wattla)), (A. cordellensis, (Armina sp., A. juliana))), (A. tigrina, A. elongata)))). The monophyletic evidence for Armina is discussed and compared to possible speciation processes similar to those found in other Opisthobranchia groups.

scholarly journals A new bathyal ophiacanthid brittle star (Ophiuroidea: Ophiacanthidae) with Caribbean affinities from the Plio-Pleistocene of the Mediterranean

Zootaxa ◽  
2020 ◽  
Vol 4820 (1) ◽  
pp. 19-30
Author(s):  
LEA D. NUMBERGER-THUY ◽  
BEN THUY
Keyword(s):  
Deep Sea ◽  
Fossil Record ◽  
Brittle Star ◽  
Morphological Comparison ◽  
Western Atlantic ◽  
Faunal Turnover ◽  
Unknown Species ◽  
Recent Species ◽  
The Mediterranean ◽  
New Discovery

Identifiable remains of large deep-sea invertebrates are exceedingly rare in the fossil record. Thus, every new discovery adds to a better understanding of ancient deep-sea environments based on direct fossil evidence. Here we describe a collection of dissociated skeletal parts of ophiuroids (brittle stars) from the latest Pliocene to earliest Pleistocene of Sicily, Italy, preserved as microfossils in sediments deposited at shallow bathyal depths. The material belongs to a previously unknown species of ophiacanthid brittle star, Ophiacantha oceani sp. nov. On the basis of morphological comparison of skeletal microstructures, in particular spine articulations and vertebral articular structures of the lateral arm plates, we conclude that the new species shares closest ties with Ophiacantha stellata, a recent species living in the present-day Caribbean at bathyal depths. Since colonization of the deep Mediterranean following the Messinian crisis at the end of the Miocene was only possibly via the Gibraltar Sill, the presence of tropical western Atlantic clades in the Plio-Pleistocene of the Mediterranean suggests a major deep-sea faunal turnover yet to be explored.

Description of cryptic taxa within the Alpheus bouvieri A. Milne-Edwards, 1878 and A. hebes Kim and Abele, 1988 species complexes (Crustacea: Decapoda: Alpheidae)

Zootaxa ◽  
2009 ◽  
Vol 2153 (1) ◽  
pp. 1-23 ◽  
Author(s):  
ARTHUR ANKER ◽  
CARLA HURT ◽  
NANCY KNOWLTON
Keyword(s):  
Genetic Data ◽  
Eastern Pacific ◽  
Northeastern Brazil ◽  
Western Atlantic ◽  
Isthmus Of Panama ◽  
Species Complexes ◽  
The Caribbean ◽  
Cryptic Taxa ◽  
Coi Sequences ◽  
Final Closure

Alpheus bouvieri A. Milne-Edwards, 1878 and A. hebes Kim and Abele, 1988 are reviewed based on morphological and genetic data. Alpheus bouvieri, previously believed to be distributed in the eastern Pacific and Atlantic, is restricted to the Atlantic populations; the eastern Pacific populations (A. bouvieri sensu Kim and Abele 1988) are assigned to A. javieri n. sp. A second new species, A. agilis n. sp., closely related to the eastern Pacific A. hebes, is described based on recently collected specimens from the eastern Atlantic (São Tomé, Cape Verde) and western Atlantic (Atol das Rocas off northeastern Brazil). The absence of A. agilis n. sp. (or any other representative of the A. hebes clade) in the Caribbean Sea is likely due to a relatively recent (~1–2 my) extinction. Genetic data (COI sequences) indicates that A. bouvieri and A. javieri n. sp., and A. hebes and A. agilis n. sp. diverged approximately 6 and 7.5 mya, respectively, i.e., around 3 my before the final closure of the Isthmus of Panama.

Occurrence and biogeographic significance of Heliaster (Echinodermata: Asteroidea) from the Pliocene of southwest Florida

1988 ◽  
Vol 62 (01) ◽  
pp. 126-132 ◽  
Author(s):  
Douglas S. Jones ◽  
Roger W. Portell
Keyword(s):  
Central American ◽  
Eastern Pacific ◽  
Whole Body ◽  
Marine Fauna ◽  
Western Atlantic ◽  
Southwest Florida ◽  
Extant Species ◽  
Geologic Record ◽  
Central American Isthmus

Whole body asteroid fossils are rare in the geologic record and previously unreported from the Cenozoic of Florida. However, specimens of the extant species,Heliaster microbrachiusXantus, were recently discovered in upper Pliocene deposits. This marks the first reported fossil occurrence of the monogeneric Heliasteridae, a group today confined to the eastern Pacific. This discovery provides further non-molluscan evidence of the close similarities between the Neogene marine fauna of Florida and the modern fauna of the eastern Pacific. The extinction of the heliasters in the western Atlantic is consistent with the pattern of many other marine groups in the region which suffered impoverishment following uplift of the Central American isthmus.

scholarly journals Evaluating the role of contracting and expanding rainforest in initiating cycles of speciation across the Isthmus of Panama

2012 ◽  
Vol 279 (1742) ◽  
pp. 3520-3526 ◽  
Author(s):  
Brian Tilston Smith ◽  
Amei Amei ◽  
John Klicka
Keyword(s):  
Bird Species ◽  
Tropical Regions ◽  
Isthmus Of Panama ◽  
Species Pairs ◽  
The Matrix ◽  
High Species Richness ◽  
The Rich ◽  
The Tropics ◽  
The Impact

Climatic and geological changes across time are presumed to have shaped the rich biodiversity of tropical regions. However, the impact climatic drying and subsequent tropical rainforest contraction had on speciation has been controversial because of inconsistent palaeoecological and genetic data. Despite the strong interest in examining the role of climatic change on speciation in the Neotropics there has been few comparative studies, particularly, those that include non-rainforest taxa. We used bird species that inhabit humid or dry habitats that dispersed across the Panamanian Isthmus to characterize temporal and spatial patterns of speciation across this barrier. Here, we show that these two assemblages of birds exhibit temporally different speciation time patterns that supports multiple cycles of speciation. Evidence for these cycles is further corroborated by the finding that both assemblages consist of ‘young’ and ‘old’ species, despite dry habitat species pairs being geographically more distant than pairs of humid habitat species. The matrix of humid and dry habitats in the tropics not only allows for the maintenance of high species richness, but additionally this study suggests that these environments may have promoted speciation. We conclude that differentially expanding and contracting distributions of dry and humid habitats was probably an important contributor to speciation in the tropics.

Distribution, history, and taxonomy of the Thais clade (Gastropoda: Muricidae) in the Neogene of tropical America

2001 ◽  
Vol 75 (3) ◽  
pp. 697-705 ◽  
Author(s):  
Geerat J. Vermeij
Keyword(s):  
New Species ◽  
South Atlantic ◽  
Eastern Pacific ◽  
Caribbean Region ◽  
Large Species ◽  
The South ◽  
Western Atlantic ◽  
Extinction Rates ◽  
Tropical America ◽  
The Caribbean

The earliest known members of the Thais clade of rapanine muricid neogastropods comprise four species from the Cantaure Formation (early Miocene: Burdigalian) of Venezuela; three of these species are new. Neorapana rotundata Gibson-Smith et al., 1997, is most closely related to the Recent Pacific Mexican N. tuberculata (Sowerby, 1835), and represents the only known Atlantic occurrence of the genus. Thais brevicula new species is closest to T. callaoensis (Gray, 1828) from the Recent of northern Peru and the Galápagos. A review of the genus Thais indicates that the typical members of this group occur in the South Atlantic, West Africa, and eastern Pacific, but not in the Recent fauna of the southern Caribbean. Stramonita bifida new species is a large species related to the Recent S. haemastoma floridana (Conrad, 1837), which occurs throughout the Caribbean. A review of American species of Stramonita indicates that the taxon S. biserialis (de Blainville, 1832) from the Recent fauna of the eastern Pacific, and the taxon S. h. haemastoma (Linnaeus, 1767), may each be composed of more than one species despite the teleplanic dispersal of their larvae. Stramonita semiplicata new species is closely related to the Recent S. bicarinata (de Blainville, 1832) from the South Atlantic, and represents a lineage that occurred in the Caribbean region until at least the late Miocene. It may have given rise to the eastern Pacific genus Acanthais. The higher diversity and greater antipredatory specialization of eastern Pacific as compared to western Atlantic members of the Thais clade may have resulted from higher post-Miocene rates of speciation and lower extinction rates in the eastern Pacific.

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