Benjamin W. van Ee’s research while affiliated with University of Puerto Rico System and other places

Biotic indices (bioindicators) can be individual species, species groups, or communities of species used to assess habitat quality. But, to be used effectively, managers require basic information on species used as indicators, including species distribution, differentiation between similar species, and environmental conditions associated with species presence. We addressed these problems concurrently in two related species, the Mottled Sculpin (Cottus bairdii) and the Slimy Sculpin (Cottus cognatus), as habitat quality indicators in the Manistee River in Michigan, USA. We determined the abundance and distribution of these species and related their presence to concurrent in-stream measurements of temperature, dissolved oxygen, pH, conductivity, turbidity, and stream quality score based on macroin-vertebrate diversity. Cladistic analyses of CO1 supported recognition of Mottled Sculpin and Slimy Sculpin as distinct species and confirmed initial field identification to species using morphological characteristics. Both species were most abundant in headwater regions, decreased downstream, and were sympatric at 5 of 12 (42%) locations. Mottled Sculpin were associated with lower conductivity, pH, and stream quality scores. Slimy Sculpin were associated with higher levels of DO and lower levels of turbidity. As a management indicator species of the US Forest Service, Mottled Sculpin alone may be ineffective as a habitat quality indicator, but concurrent use of Mottled Sculpin and Slimy Sculpin as a related-species complex might allow sufficient coverage to permit assessment of stream quality if species-specific differences in environmental tolerances are precisely determined.

Biological indicators (bioindicators) can be individual species or species groups used to assess habitat quality. Unfortunately, conservationists often lack information on species distribution, how to differentiate between similar species, and environmental conditions associated with the presence of a species. We addressed these problems using two “sister” species of fish, the Mottled Sculpin (Cottus bairdii) and the Slimy Sculpin (Cottus cognatus), as stream quality indicators in the Manistee River watershed in the Huron-Manistee National Forests in Michigan, USA. We determined the abundance and distribution of these species and related their presence to concurrent in-stream measurements of temperature, dissolved oxygen, pH, conductivity, turbidity, and stream quality score based on macroinvertebrate diversity. To be certain of identification, we sequenced the Cytochrome c Oxidase Subunit I (CO1) molecular marker for specimens and used it as a DNA barcode to determine a specimen’s species. Cladistic analyses of CO1 unambiguously supported recognition of Mottled Sculpin and Slimy Sculpin as distinct species, confirming initial 87.5% correct identification using morphological characteristics, with uncertainty limited to juvenile fish. Field determinations increased to 100% correct identification as investigators gained more experience. Both species were most abundant in headwater regions, decreased downstream, and were sympatric at several locations. Mottled Sculpin were more likely to be found at stream locations with lower conductivity, pH, and stream quality scores, whereas Slimy Sculpin presence was more strongly associated higher levels of DO and lower levels of turbidity. Such findings are important because Mottled Sculpin are a designated management indicator species of the US Forest Service in the Huron-Manistee National Forests, but may be ineffective as a habitat quality indicator when used alone. Concurrent use of Mottled Sculpin and Slimy Sculpin as a management indicator sister-species complex could allow sufficient landscape coverage to permit habitat assessment if species-specific differences in environmental tolerances are precisely determined.

A revised assessment of Croton L. sect. Geiseleria (A. Gray) Baill. is provided. The section as now circumscribed includes 84 species ranging across warm areas of the Americas. A nuclear ITS phylogeny of 150 accessions from 83 species and a chloroplast trnL-F phylogeny of 89 accessions from 65 species were generated to confirm correct phylogenetic placement of the species and to determine if any species previously included in the section should now be excluded. Seven new species are described, and we present a taxonomic synopsis that lists all currently accepted species along with their synonyms, distributions, and pertinent comments. We also recognize four subsections within Croton sect. Geiseleria and list their corresponding species. Based on both morphological and molecular criteria, we now recognize C. lagunillae Croizat as a distinct species, rather than as a variety of C. guildingii Griseb. (now treated as C. suavis Kunth), and we treat C. ramillatus Croizat var. magniglandulifer V. W. Steinm. as a species, C. magniglandulifer (V. W. Steinm.) B. W. van Ee. We also exclude C. tetradenius Baill. from Croton sect. Geiseleria (A. Gray) Baill. along with related species such as C. pulegiodorus Baill. and C. leptobotryus Müll. Arg., which are either members of Croton sect. Adenophylli Griseb. or else may merit new sectional status. We also exclude C. waltherioides Urb., although it is not clear to which section of Croton it belongs.

We evaluated the impact of the Harrisia Cactus Mealybug (HCM), Hypogeococcus sp. (Hemiptera: Pseudococcidae), on seed germination of Pilosocereus royenii (Cactaceae) in Puerto Rico. Mature fruits were collected from individuals of P. royenii at various levels of HCM infestation, ranging from completely healthy plants to fruits growing directly on HCM-induced tumors. We hypothesized that germination will be directly and negatively affected by HCM infestation severity. After measuring germination and seedling survival for 160 days, we observed that seeds from fruits growing on tumors had the lowest germination rate compared to the other categories, as hypothesized. In addition, lightly infested plants germinated at a lesser rate compared to healthy plants, while seeds from severely infested plants germinated at a greater rate, contrasting with our hypothesis. We suggest that when the infestation is light, the host might be reallocating resources towards developing defensive responses. In contrast, when the infestation is severe, the host might be reallocating resources toward increasing germination.

Croton kinondoensis, a new species from Kenya, is described and illustrated here with photographs. It is found in the sacred Kaya Kinondo Forest, one of the last remaining coastal forests patches in Kenya. Its morphology and systematic position based on ITS and trnL-F DNA sequence data clearly place it within the Adenophorus Group of Croton, a clade of ca. 15 species otherwise known only from Madagascar and the Comoros Archipelago. Its closest affinities appear to lie with Croton mayottae, from the island of Mayotte, and C. menabeensis, from northwestern Madagascar. This new species likely represents an independent dispersal of Croton from Madagascar to mainland Africa.