Spawning clasps and gamete deposition in pebble nest-building minnows (pisces : cyprinidae)

Spawning in five species of North American cyprinid minnows (Rhinichthys a. atratulus, Exog/ossum laurae, Semotilus atromaculatus, Nocomis leptocephalus, and N. micropogon ) are analyzed on videotape filmed in Virginia and Maryland streams. Behaviors are chronologically resolved into a sequence of categories (Interim, Approach, Alignment, Run, Clasp and Dissociation) exemplary of a successful spawn as defined by the clasp. The categories are used to describe spawning behaviors in each species. In all species studied, a successful spawn is a female initiated event effecting the clasping response of a male. The species-specific pattern of male-female interactions not only reflects the coordination of the spawning clasp, but the architecture of the spawning substrate. In the pebble nest-building cyprinids (i. e., species of Exoglossum, Semotilus and Nocomis ) a successful spawn is the end result of a topographically fixed sequence of behaviors that place the clasped pair over a discrete area of the nest specifically composed for gamete deposition and retention

Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator

Is there only one electric eel species? For two and a half centuries since its description by Linnaeus, Electrophorus electricus has captivated humankind by its capacity to generate strong electric discharges. Despite the importance of Electrophorus in multiple fields of science, the possibility of additional species-level diversity in the genus, which could also reveal a hidden variety of substances and bioelectrogenic functions, has hitherto not been explored. Here, based on overwhelming patterns of genetic, morphological, and ecological data, we reject the hypothesis of a single species broadly distributed throughout Greater Amazonia. Our analyses readily identify three major lineages that diverged during the Miocene and Pliocene—two of which warrant recognition as new species. For one of the new species, we recorded a discharge of 860 V, well above 650 V previously cited for Electrophorus, making it the strongest living bioelectricity generator. © 2019, The Author(s)

Taxonomy of the Neotropical Thorny Catfishes (Siluriformes: Doradidae) and Revision of Genus Leptodoras

422 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2002.Cladistic analysis of relationships among Leptodoras and related taxa (Anduzedoras, Doras, Hassar, Hemidoras) using morphological data recovers Leptodoras praelongus (Myers & Weitzman) as the most ancestral species. The most derived clade is composed of two nominal species, Leptodoras juruensis Boulenger and Leptodoras myersi Bohlke, and one undescribed species, Leptodoras sp. 3. A sister-group relationship between Leptodoras and the monotypic Anduzedoras oxyrhynchus (Valenciennes) is supported by four unambiguous synapomorphies: predorsal distance ≤41% of standard length, first vertebra conspicuously expanded, maxillary edentulous, and average sum of midlateral scutes ≥70. This relationship and those among species of Leptodoras suggest a gradual evolution from a midwater or hyperbenthic form to a truly benthic, relatively deepwater form.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Taxonomy of the Neotropical Thorny Catfishes (Siluriformes: Doradidae) and Revision of Genus Leptodoras

422 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2002.Cladistic analysis of relationships among Leptodoras and related taxa (Anduzedoras, Doras, Hassar, Hemidoras) using morphological data recovers Leptodoras praelongus (Myers & Weitzman) as the most ancestral species. The most derived clade is composed of two nominal species, Leptodoras juruensis Boulenger and Leptodoras myersi Bohlke, and one undescribed species, Leptodoras sp. 3. A sister-group relationship between Leptodoras and the monotypic Anduzedoras oxyrhynchus (Valenciennes) is supported by four unambiguous synapomorphies: predorsal distance ≤41% of standard length, first vertebra conspicuously expanded, maxillary edentulous, and average sum of midlateral scutes ≥70. This relationship and those among species of Leptodoras suggest a gradual evolution from a midwater or hyperbenthic form to a truly benthic, relatively deepwater form.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Platydoras birindellii, new species of striped raphael catfish (Siluriformes: Doradidae) from the Xingu Basin, Brazil

A new species of Platydoras is described from the rio Xingu Basin, Brazil. Platydoras birindellii is distinguished from congeners by having gas bladder simple (vs. with posterior secondary chamber) and dorsal and caudal fins uniformly dusky (vs. with distinct marks composed of dark broad band or blotch on central portion of dorsal fin and pair of dark broad stripes on caudal fin, one central to each lobe). Platydoras birindellii shares a simple gas bladder with the sister taxon to Platydoras, Centrochir crocodili, a monotypic genus endemic to the Magdalena Basin. With respect to the caudal skeleton, the parhypural is incompletely fused to hypurals 1+2 in P. birindellii, a condition that is intermediate between those of Centrochir (parhypural typically separated from hypurals 1+2 by distinct suture) and Platydoras (parhypural typically fully fused to hypurals 1+2). Platydoras birindellii is commonly found in rocky clearwater rapids and apparently endemic to the middle and upper portions of the Xingu draining the Brazilian Shield. © 2018 by the Academy of Natural Sciences of Drexel University