Charles H. Nelson

A new simplified method for constructing Wagner networks and the cladistics of Pentachaeta (Compositae, Astereae)

The new procedure for constructing a Wagner network presented differs from Farris’s (1970) method in that the amount of computation required is reduced. The usefulness of this procedure was examined by applying it to the 20 characters considered in a recent monograph of the seven OTUs of the genusPentachaeta. A single network was derived from some 945 or more networks possible for this group. A comparison of the network constructed by this simplified method to that constructed by Farris’ procedure revealed no differences. An attempt to reconstruct the cladistic history of this group by generating a Wagner tree based on the network resulted in four equally possible trees, suggesting that further data are needed before cladogenesis in this group is resolved.

Surface ultrastructure and evolution of tarsal attachment structures in Plecoptera (Arthropoda: Hexapoda)

The plantar surfaces of the stonefly tarsomeres and pretarsus are examined chiefly using scanning electron microscopy (SEM) of 39 Plecoptera exemplar species representing each family within the two suborders Arctoperlaria and Antarctoperlaria. Features examined include the shape and size of the tarsomeres as well as external features of the plantar surfaces of the tarsomeres, unguitractor plate, claws, arolium and orbicula. Characteristics presumed to be part of the stonefly ground pattern were determined by mapping these features on a cladogram of stonefly phylogeny (Zwick 2000, Annual Review of Entomology 45:709–746). This analysis indicates that the following characters are part of the stonefly ground pattern: (1) cylindrical shape of the tarsomeres, (2) an elongate tarsomere 1, (3) a short tarsomere 2, (4) presence of hairy euplantulae on the plantar surfaces of tarsomeres 1 and 2, (5) absence of specialised attachment surfaces on the plantar area of tarsomere 3, (6) absence of setae on the arolium plantar surface, and (7) presence of setae on the orbicula surface. Hairs covering the euplantulae of tarsomeres 1 and 2 and the median longitudinal unscelerotised region of tarsomeres 1–3 are non-setal cuticular projections and appear to be acanthae. Hairy euplantulae are unusual and are only present in one other insect order, the Mantophasmatodea. Specialised tenent setae were not found. The presence of hairy euplantulae as part of the stonefly ground pattern contradicts the recent view (Beutel and Gorb 2006, Arthropod Systematics & Phylogeny 64:3–25) that stoneflies lack pad-like euplantulae and that the ancestral condition for tarsomeres 1 and 2 may be a narrow median longitudinal unsclerotised band such as that found in representatives of the Austroperlidae. The hypothesis that Plecoptera are the sister clade to the remaining Neoptera suggests that euplantulae might be a synapomorphy of both clades. On the other hand, placement of Plecoptera within a monophyletic Polyneoptera clade within the Neoptera suggests that euplantulae could be an autapomorphy of this subordinate clade.

Effects of stream acidification on lotic salamander assemblages in a coal-mined watershed in the Cumberland Plateau

We studied the effects of acid mine drainage (AMD) from abandoned coal mines on lotic salamanders and environmental conditions in the upper watershed (Cumberland Plateau) of North Chickamauga Creek (NCC; Tennessee River drainage) in southeastern Tennessee, USA, from 1996–97. Study sites (2nd- or 3rd-order reaches) were sampled in an AMD-influenced section (five sites) and in two reference streams (two minimally disturbed sites). A total of 212 plethodontids (premetamorphic larvae) representing four species were collected by kicknetting in riffles (n = 99) and electrofishing in mixed habitats (n = 113). The dusky salamander (Desmognathus fuscus) was the most abundant species in both AMD and reference reaches (> 80 – 90% of total catches), successively followed by the southern two-lined salamander (Eurycea cirrigera), spring salamander (Gyrinophilus porphyriticus), and red salamander (Pseudotriton ruber). Mining-influenced reaches were characterized by acidic flows (mean pH = 3.8–5.6), zero to low alkalinity, and elevated conductivity, sulfate, hardness, aluminum, and manganese, as well as very low abundances of salamanders. Reference reaches were slightly acidic to circumneutral (mean pH = 6.0–6.9) with low to moderate alkalinity, low levels of conductivity, hardness, sulfate, and metals, and high salamander abundances. Our findings document the impact of acid/metal pollution from past coal mining activities on lotic salamanders in a Cumberland Plateau stream.

Stoneflies (Plecoptera) in the diet of brook trout (Salvelinus fontinalis Mitchell) in Libby Creek, Wyoming, USA

The stonefly component of a naturally reproducing population of brook trout ( Salvelinus fontinalis) was studied by analyzing 216 stomach pump samples collected between May 15 and August 10, 1991 and 1992, from Libby Creek, an alpine stream in the Medicine Bow National Forest in Wyoming. Stoneflies constituted 10.3% of the total items recovered and were the second most abundant order in the samples. Nineteen species of Plecoptera representing five families were identified. Approximately 43% of all stoneflies were Sweltsa lamba; the next most prevalent species was Zapada haysi (12%). The other prevalent insect orders in the samples were Diptera (57.2%), Ephemeroptera (8.4%) and Trichoptera (6.1%). Terrestrial Coleoptera, Hymenoptera, and Hemiptera were most common in July and August.

New State, County, and Drainage Basin Records of West Virginia (USA) Stoneflies (Plecoptera)

ABSTRACT: Based on recent collections, the checklist of the stoneflies of West Virginia is updated to include 140 species. Four state records, 154 county records and 16 drainage basin records are added to the plecopteran fauna of the state. Range extensions are noted for Perlesta lagoi Stark, P. shubata Stark, P. puttmanni Kondratieff and Kirchner and Neoperla robisoni Poulton and Stewart. Distributions of the new records in seven major drainage basins of West Virginia are presented.

Seasonal changes in the stonefly (Plecoptera) component of the diet profile of trout in Big Hunting Creek, Maryland, USA

The stonefly (Plecoptera) component of the trout diet profile was studied by analyzing 172 stomach pump samples collected between February, 1986, and December, 1989, in Big Hunting Creek, Maryland. Samples were obtained from a naturally reproducing population of brown trout (Salmo trutta) and a stocked population of rainbow trout (Oncorhynchus mykiss) caught between the boundaries of Catoctin Mountain Park and Cunningham Falls State Park. Eighty‐one of the samples contained a total of 1596 Plecoptera, 88% of which were adults. Twenty species were identified representing 7 families and 15 genera, with the dominant species being the winter stonefly, Allocapnia nivicola. Approximately 93% of the Plecoptera were represented by the winter stonefly species Allocapnia nivicola, A. granulata, A. recta, A. rickeri, Paracapnia angulata and Taeniopteryx maura. Recorded as a percentage of the total number of items recovered per month, stoneflies account for 47% (December), 82% (January), 70% (February), and 57% (Marc...