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We document development type for 33 species of benthic opisthobranch gastropods – 15 for the first time – collected mainly from the Southern California Bight. Fourteen of the newly examined species had planktotrophic development, while the dorid nudibranch Atagema alba had capsular metamorphic development, the first example of direct development in a non-dendrodoridid nudibranch known from the northeast Pacific Ocean. For the remaining 18 species our new data are either consistent with earlier determinations of development type, or confirm previous inferences. The new data also broaden geographic coverage for some species, and for the sacoglossan Stiliger fuscovittatus and the nudibranch Melibe leonina, suggest that egg size is inversely related to temperature. We correct the previous erroneous identification of nephrocysts as eyespots in the hatching planktotrophic larvae of the nudibranchs Tritonia festiva and Janolus fuscus. These results further highlight the predominance of planktotrophic development in benthic opisthobranchs from the northeast Pacific Ocean.
Wildfires in southern California chaparral burn at high intensities and often cover thousands of hectares. Some small mammals survive the fire, while others colonize from scattered unburned islands and from intact vegetation bordering the main fire perimeter. For ten years (2002–2011) we live-trapped two grids and used the number of captures to examine post-fire small mammal use of a narrow 65-m zone straddling the high-contrast edge between burned and unburned chaparral on the perimeter of a high-intensity wildfire. Results indicate that agile kangaroo rats (Dipodomys agilis) were captured more often in open, burned areas than in unburned chaparral. Deer mice (Peromyscus maniculatus) were captured equally in burned and unburned chaparral but did not show an affinity for either habitat or the edge of the burn. Pinyon mice (Peromyscus truei) were captured most often in unburned chaparral throughout the study but were prevalent on the burn edge in years one and four. In the first year post-fire, California mice (Peromyscus californicus) were captured more frequently in unburned than burned chaparral but in years four and five, captures shifted toward the edge and then into the burn areas in year nine. We did not find evidence that any of the four species were dedicated edge specialists in this study. Neither pinyon mice nor California mice appeared to be permanent residents of the burns in the first ten years post-fire. We suggest that future research on post-fire small mammal succession in chaparral would benefit from chronosequence studies that give a more comprehensive, long term picture of succession.
The family Cetorhinidae Gill includes one extant genus, Cetorhinus Blainville, and a single living species, the basking shark, C. maximus (Gunnerus). Basking sharks are coastal pelagic to oceanic with circumglobal distribution in boreal to warm-temperate waters of the continental and insular shelves. Second only in size to the whale shark, Rhincodon typus, basking sharks attain a maximum total length of 12 to 15 m (although generally not exceeding 9.8 m), and are planktivorous, feeding by filtering copepods, barnacles, decapod larvae and fish eggs from the water. The first Tertiary records of undisputed cetorhinids are from the middle Eocene of Antarctica, possibly the middle Eocene of Russia, and the late Eocene of Oregon. Eocene cetorhinids are referred to Keasius taylori, and Oligocene through early Miocene basking sharks are traditionally assigned to Keasius parvus. The earliest occurrence of Cetorhinus in the northeastern Pacific is early Miocene, and fossils attributed to this genus are relatively common in middle Miocene through Pleistocene marine sediments of Oregon, California, and Baja California, Mexico. Late Miocene and younger Cetorhinus are conventionally placed in the extant species, C. maximus. Late Miocene fossils of a basking shark from the Coos Conglomerate Member of the Empire Formation, Oregon, were collected in 1972 by students from the University of California, Berkeley. Associated vertebrae and gill rakers compare favorably in size and overall morphology with those of adult Recent C. maximus. Based on correlations of vertebral and gill raker dimensions with the total length for Recent C. maximus, the Empire basking shark is estimated to have been between 4.5 and 5.75 m in total length. Although gill rakers and vertebrae from the Empire Formation compare favorably with those of C. maximus, a definitive identification requires dentition. The occurrence of Cetorhinus cf. C. maximus in the late Miocene of Oregon is consistent with other late Miocene records of this species in California and Chile. C. maximus may range no earlier than late Miocene in the eastern North Pacific.