scholarly journals Morphological variation in the hydromedusa genus Polyorchis on the west coast of North America

1980 ◽  
Vol 58 (11) ◽  
pp. 2089-2095 ◽  
Author(s):  
John T. Rees ◽  
R. J. Larson
Keyword(s):  
North America ◽  
Morphological Variation ◽  
West Coast ◽  
Baja California ◽  
Geographic Range ◽  
Valid Species ◽  
The West ◽  
Radial Canal

Morphological variation in the hydromedusan genus Polyorchis on the west coast of North America is analyzed in relation to gonad number, tentacle number, and radial canal diverticula number relative to the height of the bell. In specimens of Polyorchis examined, it is concluded that P. penicillatus (Eschscholtz, 1829) is highly variable morphologically over its known geographic range from Alaska to Baja California. Polyorchis montereyensis Skogsberg, 1948 is considered a synonym of P. penicillatus, and P. haplus Skogsberg, 1948, is retained as a valid species.

Geographic range in Chthamalus along the west coast of North America

2005 ◽  
Vol 85 (2) ◽  
pp. 327-331 ◽  
Author(s):  
J.P. Wares ◽  
A.E. Castañeda
Keyword(s):  
North America ◽  
Cryptic Species ◽  
Genetic Markers ◽  
West Coast ◽  
Environmental Gradients ◽  
Geographic Range ◽  
The West ◽  
Barnacle Species ◽  
Range Overlap

Identification of the range boundaries and microgeographic distribution of cryptic species is greatly facilitated by the use of genetic markers. Here we characterize the geographic range overlap between two cryptic species, Chthamalus fissus and C. dalli, and show that as with other barnacle species, their distribution and abundance is probably dictated more by microhabitat characteristics and the presence of conspecifics than broader environmental gradients. We also show that C. dalli appears to be panmictic across the studied range.

New early Eocene marine gastropods from Baja California Sur, Mexico

1990 ◽  
Vol 64 (1) ◽  
pp. 99-103 ◽  
Author(s):  
Richard L. Squires ◽  
Robert Demetrion
Keyword(s):  
North America ◽  
West Coast ◽  
Baja California ◽  
Western Hemisphere ◽  
Baja California Sur ◽  
The West ◽  
Lower Eocene ◽  
Marine Gastropods ◽  
First Occurrence ◽  
Molluscan Fauna

Three gastropod species are described from a previously unknown shallow-marine molluscan fauna in the lower Eocene Bateque Formation, southwest of San Ignacio, Baja California Sur, Mexico. Velates batequensis n. sp., a commonly occurring neritid in the Bateque, is the only ribbed Velates known from the Western Hemisphere. The fairly rare Platyoptera pacifica n. sp. is the earliest record of this strombid genus and its first occurrence on the west coast of North America. The very rare Cypraedia sp. is also the first occurrence of this cypraeid-like genus on the west coast of North America.

PHORONIDEA FROM THE PACIFIC COAST OF NORTH AMERICA

1959 ◽  
Vol 37 (2) ◽  
pp. 87-111 ◽  
Author(s):  
Joan Rattenbury Marsden
Keyword(s):  
North America ◽  
West Coast ◽  
Pacific Coast ◽  
Geographic Range ◽  
The West ◽  
Taxonomic Relationships ◽  
The Pacific ◽  
Phoronopsis Harmeri

Six phoronids from the west coast of North America, Phoronis vancouverensis, Phoronis pallida, Phoronis psammophila, Phoronis ovalis, Phoronopsis harmeri, and one that is possibly Phoronis architecta, are described. Phoronopsis harmeri is considered to be synonymous with Phoronopsis viridis. Taxonomic relationships within the Phoronidea are discussed. It is suggested that the phylum may most naturally be divided into four categories of wide geographic range. The characteristics of each of these categories are discussed.

New Eocene marine bivalves from Baja California Sur, Mexico

1990 ◽  
Vol 64 (3) ◽  
pp. 382-391 ◽  
Author(s):  
Richard L. Squires ◽  
Robert Demetrion
Keyword(s):  
North America ◽  
West Coast ◽  
Type Species ◽  
Baja California ◽  
Middle Eocene ◽  
Central Area ◽  
Baja California Sur ◽  
Left Valve ◽  
The West ◽  
Lower Eocene

A new genus, a new subgenus, and five new species of pterioid bivalves are described from shallow-marine faunas in the middle lower to middle Eocene Bateque Formation in the vicinity of Laguna San Ignacio to about 105 km southward, Pacific coast of Baja California Sur, Mexico. Batequeus n. gen. is a medium-sized pectinid with equally convex valves, a short byssal notch, anterior auricles smaller than the posterior ones, the left valve with numerous very closely spaced radial riblets that show the imbricated growth lines very well, the right valve with about 30 low, flat-topped radial ribs that can be grooved, and intercalary ribs on both valves. It is only known from its type species, Batequeus mezquitalensis n. sp., which is from the middle Eocene part of the Bateque Formation. Spondylus batequensis n. sp., a very spinose species, is from the middle lower Eocene part of the Bateque Formation and is only the second reported Spondylus from the lower Eocene of the west coast of North America. Pycnodonte (Phygraea) pacifica n. sp., a species characterized by a radial sulcus that originates in the umbo area, occurs in both the middle lower and middle Eocene parts of the Bateque Formation. Phygraea has not been reported previously from the west coast of North America. Pycnodonte (Pegma) n. subgen. has a plicate left valve with a large attachment area (that can cover the entire valve) and a right valve that usually has an inflated smooth central area surrounded by plicate margins. It is only known from its type species, Pycnodonte (Pegma) bajaensis n. sp., which occurs in both the middle lower and middle Eocene parts of the Bateque Formation. Cubitostrea mezquitalensis n. sp., a strongly ornamented species, is from the middle Eocene part of the Bateque Formation and is the first occurrence of this genus from the west coast of North America.

The Lower Jurassic phosphorites of southeastern British Columbia and terrane accretion to western North America

1989 ◽  
Vol 26 (8) ◽  
pp. 1612-1616 ◽  
Author(s):  
T. P. Poulton ◽  
J. D. Aitken
Keyword(s):  
British Columbia ◽  
North America ◽  
Oceanic Crust ◽  
West Coast ◽  
Cold Water ◽  
Lower Jurassic ◽  
Depositional Model ◽  
Western North America ◽  
The West ◽  
Terrane Accretion

Sinemurian phosphorites in southeastern British Columbia and southwestern Alberta conform with the "West Coast type" phosphorite depositional model. The model indicates that they were deposited on or near the Early Jurassic western cratonic margin, next to a sea or trough from which cold water upwelled. This suggests that the allochthonous terrane Quesnellia lay well offshore in Sinemurian time. The sea separating Quesnellia from North America was partly floored by oceanic crust ("Eastern Terrane") and partly by a thick sequence of rifted, continental terrace wedge rocks comprising the Purcell Supergroup and overlying Paleozoic sequence. This sequence must have been depressed sufficiently that access of upwelling deep currents to the phosphorite depositional area was not impeded.

Squat lobsters (Crustacea: Decapoda: Anomura: Galatheoidea) from off the northwestern coast of the Baja California Peninusla, Mexico

Zootaxa ◽  
2021 ◽  
Vol 4965 (2) ◽  
pp. 375-384
Author(s):  
MICHEL E. HENDRICKX
Keyword(s):  
West Coast ◽  
Gulf Of California ◽  
Baja California ◽  
Baja California Peninsula ◽  
The West ◽  
Western Mexico ◽  
Exploratory Survey ◽  
Northwestern Coast ◽  
First Time ◽  
Squat Lobsters

Four species of squat lobsters were collected off the northwestern coast of the Baja California Peninsula, Mexico, during an exploratory survey of fishing resources. Janethogalathea californiensis, described from California was previously known from off the west coast of the Baja California Peninsula (two localities) and from the Gulf of California (three localities). Of the three species of Munida collected during the survey, M. tenella is recorded off the west coast of the Baja California Peninsula for the first time. These are the fourth record of M. hispida and the second record of M. quadrispina in western Mexico.

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