Pacific Science, vol. 61, no. 2 (2007)

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Conservation Status of the Endemic Bees of Hawai‘i, Hylaeus (Nesoprosopis) (Hymenoptera: Colletidae)
Karl N. Magnacca, 173

The 60 species of native Hylaeus bees in the Hawaiian Islands are important pollinators in native ecosystems, but they have been almost completely ignored in conservation studies. The only previous assessment of the conservation status of the individual species was not based on recent collections. Here I report on conservation status of all known species, based on collections made from 1999 to 2002. Species are arranged into six categories according to degree of threat, and species considered to be threatened are discussed individually. Five species have not been collected recently from one or more islands from which they are historically known, seven are restricted to endangered habitat, 10 are considered to be very rare and potentially endangered, and 10 have not been collected recently and could be extinct. With such a high proportion of rare species and the importance of Hylaeus species as pollinators, further work on their ecology is needed.

Reproductive Biology of the Brown Tree Snake, Boiga irregularis (Reptilia: Colubridae), during Colonization of Guam and Comparison with That in Their Native Range
Julie A. Savidge, Fiona J. Qualls, and Gordon H. Rodda, 191

Since their introduction to Guam shortly after World War II, brown tree snakes, Boiga irregularis (Merrem), have seriously impacted the biota and human population of the island. Understanding the biology of this exotic species will likely be important to the success of control programs. We compared the reproductive biology of 782 B. irregularis caught on Guam during the 1980s with results from published studies of native-range populations. Average and maximum sizes of mature snakes on Guam were larger than those from Australian populations. The majority of female brown tree snakes matured at snout-vent lengths (SVLs) of 910–1,025 mm, and most males matured at SVLs of 940–1,030 mm on Guam. Based on growth rates from the early 1990s on Guam, sexual maturity is estimated to occur during a snake’s third or fourth year. Only one female (0.3%) in our data set had oviductal eggs. Clutch size was estimated at 4.3 (SD = 2.2), based on large vitellogenic ovarian follicle (≥30 mm in length) and oviductal egg counts. Unlike their Australian counterparts, the Guam population reproduced year-round. Our data offer insights into the likely reproductive patterns of brown tree snakes should they infest other islands in the Pacific region.

Consistent Frequency of Color Morphs in the Sea Star Pisaster ochraceus (Echinodermata: Asteriidae) across Open-Coast Habitats in the Northeastern Pacific
Peter Raimondi, Raphael D. Sagarin, Richard Ambrose, Christy Bell, Maya George, Steven Lee, David Lohse, C. Melissa Miner, and Steven Murray, 201

The sea star Pisaster ochraceus (Brandt, 1835) is among the most conspicuous members of northeastern Pacific rocky-shore fauna due to its dramatic color variation, ranging from bright yellowish orange to brown to deep purple. Despite a large body of ecological and developmental biology information on P. ochraceus, few studies have rigorously examined color patterns or their causes across its geographic range. We used thousands of observations of sea star color and size taken from southern California to northern Oregon to show that the frequency of orange sea stars is approximately 20% with little variation across a broad latitudinal band. However, the frequency of orange sea stars in a population increases with the size of the animals in most populations. We consider several alternative hypotheses for these color patterns but find that the most parsimonious explanation is that adult color is a selectively neutral genetic trait that expresses itself ontogenetically. These novel findings point to the need for renewed study of the basic biology of this key ecological species.

Interspecific Spawning between a Recent Immigrant and an Endemic Damselfish (Pisces: Pomacentridae) in the Hawaiian Islands
Karen P. Maruska and Kimberly A. Peyton, 211

The Indo-Pacific damselfish Abudefduf vaigiensis (Quoy & Gaimard, 1825) was first observed in the Hawaiian Islands in the early 1990s and is now clearly established as a breeding population in the Islands. Sightings of fish with color patterns intermediate between those of A. vaigiensis and the very similar endemic Hawaiian sergeant, Abudefduf abdominalis (Quoy & Gaimard, 1825), suggest that hybridization of the two has occurred naturally. This study provides direct evidence of crossbreeding from observations and video footage of two separate spawnings in nearshore waters of O‘ahu and a third spawning in a public aquarium display tank. Reproductive behaviors were similar in intra- and interspecific spawning. However, one important difference was the absence of courtship by the male A. abdominalis toward the female A. vaigiensis in the interspecific spawnings. Instead, the female A. vaigiensis initiated spawning and the male A. abdominalis remained to fertilize, guard, fan, and clean the hybrid clutch along with a previous clutch until the embryos hatched. Embryos collected from one hybrid clutch showed normal embryonic development and subsequently hatched to produce viable swimming larvae. These observations represent a rare example of interspecific spawning in the damselfish family (Pomacentridae) and an exceptional opportunity to study hybridization and introgression in a wild population of coral reef fishes.

Genetic Population Structure of the Hawaiian Alien Invasive Seaweed Acanthophora spicifera (Rhodophyta) as Revealed by DNA Sequencing and ISSR Analyses
Daniel C. O’Doherty and Alison R. Sherwood, 223

Acanthophora spicifera (Vahl) Børgesen is the most widespread and invasive alien macroalga on coral reefs throughout the main Hawaiian Islands. This alga disperses from harbors and ports to coral reefs throughout the state, producing high quantities of biomass that affect a wide range of reef flora and fauna. Population samples of A. spicifera from across the main Hawaiian Islands were collected and compared through two kinds of analyses: DNA sequencing (based on a variable region of the nuclear large subunit ribosomal RNA gene, and the mitochondrial cox 2-3 spacer region) and fragment techniques (Inter-Simple Sequence Repeats [ISSRs]). DNA sequencing revealed no variation for the two markers, even when collections from other areas of the Pacific and Australia were included. In contrast, ISSR analyses revealed highly structured Hawaiian populations of A. spicifera with a substantial range of both within- and among-population variation, with individual plants forming discrete clusters corresponding to geographic locality.

Modeling Streamflows and Flood Delineation of the 2004 Flood Disaster, Mānoa, O‘ahu, Hawai‘i
Aly I. El-Kadi and Eric Yamashita, 235

In October 2004 a flood caused extensive damage to the University of Hawai‘i (UH) campus and neighboring residential areas in Mānoa Valley, O‘ahu, Hawai‘i. This modeling study was aimed at streamflow evaluation and flood delineation for the area impacted by the flood. The study concluded that the HEC-1 model of the U.S. Army Corps of Engineers is suitable for simulating storm runoff response for the study area, considering the nature of small Hawai‘i watersheds, which generate hydrographs with steep rising and falling limbs. The curve-number method of the U.S. Soil Conservation Service is also suitable because it predicts reasonably well the main features of streamflow hydrographs, including runoff duration and time of peaks. To improve on accuracy, however, there is a need for better characterization of spatial rainfall distribution through measurements. A flood delineation model, which treats the flood as a hypothetical dam break, was used to predict the floodwater pathway, flood zone extent, maximum flood depth, and the time to reach that depth. The model predicted an upper value for storm total flow volume that would not cause flooding on the UH campus. Although not fully validated, the developed models can guide data-collection and decision-making processes. For example, the models demonstrated that it is possible to mitigate the flood through streamflow diversion and stream dredging, realignment, and lining. For efficient management, we recommend defining a new subwatershed of the Ala Wai basin (to be called the West Mānoa Watershed) that contains the university campus.

Endemic Land Snail Fauna (Mollusca) on a Remote Peninsula in the Ogasawara Archipelago, Northwestern Pacific
Satoshi Chiba, Angus Davison, and Hideaki Mori, 257

Historically, the Ogasawara Archipelago harbored more than 90 native land snail species, 90% of which were endemic. Unfortunately, about 40% of the species have already gone extinct across the entire archipelago. On Hahajima, the second-largest island and the one on which the greatest number of species was recorded, more than 50% of species are thought to have been lost. We report here the results of a recent survey of the snails of a remote peninsula, Higashizaki, on the eastern coast of Hahajima. Although the peninsula is small (∼0.3 km²) and only part is covered by forest (<0.1 km²), we found 12 land snail species, all of which are endemic to Ogasawara. Among these species, five had been thought to already be extinct on Hahajima, including Ogasawarana yoshiwarana and Hirasea acutissima. Of the former, there has been no record since its original description in 1902. Except for the much larger island of Anijima and the main part of Hahajima, no single region on the Ogasawara Archipelago maintains as great a number of native land snail species. It is probable that the land snail fauna of the Higashizaki Peninsula is exceptionally well preserved because of a lack of anthropogenic disturbance and introduced species. In some circumstances, even an extremely small area can be an important and effective refuge for threatened land snail faunas.

Odonata of Yap, Western Caroline Islands, Micronesia
Donald W. Buden and Dennis R. Paulson, 267

Fifteen species of Odonata are recorded from Yap, Micronesia—two Zygoptera and 13 Anisoptera. None is endemic to Yap. Hemicordulia lulico occurs elsewhere only in Palau, whereas most of the other species are widespread in the western Pacific and Indo-Australian regions. Macrodiplax cora and Tramea loewi, both recorded by Lieftinck in 1962, were the only species not encountered during this study; Tramea loewi remains known in Micronesia only from a single male collected in Yap by R. J. Goss in 1950. Six of the breeding species in Yap that are widespread in Indo-Australia occur no farther east in the Caroline Islands except possibly as unusual extralimital records in the cases of Agriocnemis femina and Neurothemis terminata; the four other species reaching only as far east as Yap are Anaciaeschna jaspidea, Agrionoptera insignis, Orthetrum serapia, and Rhyothemis phyllis. Orthetrum serapia is reported from Micronesia for the first time, although a very old single specimen record of O. sabina from Tobi Island may possibly pertain to O. serapia. The odonate fauna of the outer islands of Yap State is poorly known; only six species have been recorded from among four of the 15 island groups. In addition, Tramea transmarina euryale rather than T. t. propinqua was found to be the subspecies occurring in the Chuuk Islands, contrary to earlier publications.

A New Species of Cophixalus (Anura: Microhylidae) from Misima Island, Papua New Guinea
Stephen J. Richards and Paul M. Oliver, 279

Cophixalus misimae Richards & Oliver, n. sp., is described from low-altitude rain forest on Misima Island, Louisiade Archipelago, Papua New Guinea. It is a small (males 15.5–16.1 mm, females 19.3–19.6 mm) terrestrial species with a visible tympanum, a snout that is distinctly truncate in dorsal view, unwebbed toes, a dark brown lateral stripe, and a call consisting of a train of high-pitched pulses. It is the third species of Cophixalus known from the Louisiade Archipelago and is currently known only from Misima Island.

First Record of Vegetative Cells of Pyrodinium bahamense (Gonyalucales: Goniodomataceae) in the Gulf of California
Aída Martínez-López, Ana E. Ulloa-Pérez, and Diana C. Escobedo-Urías, 289

As part of an ongoing monitoring study of phytoplankton in coastal lagoons on the east side of the Gulf of California, Pyrodinium bahamense Plate, 1906 var. bahamense was collected in the Topolobampo–Santa Maria–Ohuira coastal lagoon system in the Gulf of California in May 2005. Average concentrations of P. bahamense were 100 cells liter-1. This finding is the first observation of vegetative cells of this tropical species in the Gulf of California and represents its northernmost occurrence to date.

Metopograpsus oceanicus (Crustacea: Brachyura) in Hawai‘i and Guam: Another Recent Invasive?
Gustav Paulay, 295

The grapsid crab Metopograpsus oceanicus (Jacquinot, 1852) is recorded from the Hawaiian Islands for the first time; it appears to be established at least in Kāne‘ohe Bay on O‘ahu. I review the ecology of the species in Oceania and argue that it was introduced both to the Hawaiian Islands and Guam, likely by shipping traffic. A brief review of Metopograpsus in the Hawaiian Islands is also presented.

Association Affairs, 301


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