The use of comparative larval morphology and drumming behavior in stonefly systematics is discussed. A tentative assignment of plesiobehavioric and apobehavioric states to drumming in Plecoptera is made, based upon the described behavior of 46 North American species, representing 8 families and 25 genera. Experiments are described which show that pairs of Perlinella drymo effectively transmit and receive signals at minimum distances of 8 m through a continuous wooden rod, 5-9 mm in diameter. Communication was achieved for shorter distances of 10-200 cm by male and female P. drymo drumming in manilla paper boxes resting on foam rubber pads. Pairs of P. drymo were unable to communicate at distances of 25 cm on a 4.2 kg rock, nor were Pteronarcella badia (Hagen) at a distance of 25 cm, when male and female were on separate, dried aspen limbs.

Even though the insects of the Neotropical area had been neglected, several authors have studied different aspects of the Southern Neotropical Plecoptera (Aubert, Benedetto, Enderlein, Froehlich, Gerstaecker, Illies, Navás, Klapálek, Werner, Zwick), specially the Andean oligostenothermal cool-adapted stoneflies. Most of the Argentinian river basins are widely spread out. The upper reaches of the Negro hydrographic system are on the east slope of the Andes and discharge into the Limay and Neuquén rivers downstream. The Negro river is formed by the convergence of both rivers and presents a sequence of reservoirs (main-stream impoundments on Limay and off-channel ones at Neuquén) ; it reaches the South Atlantic coast at approximately 41 ° S. The headstreams of the Valdivia system are on the west slope of the Andes. This river, much shorter than the Negro, joins the Pacific at 40° S. Transition from rhithron to potamon is rapid, if indeed the potamon exists. Macrozoobenthic samples of these two North Patagonian river basins, Negro (Argentina) and Valdivia (Chile) were taken in the period 1977-1983 in order to compare habitats of aquatic insects and other invertebrates on both slopes of the Andes and at the same latitude. Ten genera of Plecoptera were recorded by the author as nymphs : Gripopterygidae (Antarctoperla, Limnoperla, Potamoperla, Pelurgoperla, and Araucanioperla ?), Diamphipnoidae (Diamphipnoa and Diamphipnopsis), Austroperlidae (Klapopteryx), Notonemouridae (Austronemoura) and Perlidae (Kempnyella). Most of these genera of Plecoptera were collected in the upper rhithral. Only Antarctoperla and Limnoperla were found in reservoirs, in one lake and in medium-size to wide rivers. Gripoperygids were more frequent on the Argentine side ; the other families were more abondant on the opposite slope ; this situation can probably be explained by the different ecological conditions brought about by cattle raising and dam construction.

Plecoptera collected from 11 locations along the longitudinal profile (first to fifth orders) of a Rocky Mountain stream (St. Vrain Creek) revealed distinctive spatial patterns of species diversity. Overall diversity was low near the stream source (epirhithron), attained maximum values in middle reaches, then declined dramatically concomitant with the transition from rhithron to potamon conditions. Shannon-Weaver index values ([math]) were < 1.0 at high elevations and at the potamon station, whereas [math] exceeded 3.0 in middle reaches. Species richness based on summer data alone is depressed by nearly 50 % at some locations, but the summer spatial pattern of [math] values is in general concordance with that derived from the entire data set. Species diversity patterns of consecutive summers were relatively stable considering the substantial differences in discharge. To accurately determine Plecoptera diversity patterns, it was necessary to combine data from both fine (240 µm) and coarse mesh (720 µm samples). Although a myriad of interrelated factors determine the diversity of lotic insects at a given site, summer maximum temperature and annual temperature range appear to be major variables controlling the spatial diversity pattern of Plecoptera.

The west palearctic species of Marthamea are reviewed. Adults are distinct from other European genera, but larvae and eggs are very similar to those of genus Phasganophora. M. beraudi (Navás) (Antilebanon Mts.) is re-instated as a species distinct from M. vitripennis (Burmeister). A lectotype of the latter is designated. Its range includes south-west, central and south-east Europe. Records from Syria are unconfirmed, those from Israel are erroneous. The species has in the past been confused with larvae of a Phasganophora species. M. selysii (Pictet) has brachypterous males and is known from Spain north to Meuse and Moselle rivers. Keys to adults and larvae are presented, but larval M. selysii and M. vitripennis can presently not be separated. The European Marthamea species are inhabitants of the potamon and are endangered ; they are presently already extinct in parts of their former ranges.