David C.F. Rentz

Zoogeography of the Grasshoppers and Their Relatives (Orthoptera) on the California Channel Islands

Twelve of fifty-four Orthoptera species (22-2 %) found on the eight California Channel Islands off the coast of Southern California are endemic, 11 9% in the northern four-island subgroup and 22 2 % in the southern four-island subgroup. A general analysis of the distribution of these endemics, especially those in the cricket genus Cnemotettix and those endemic species capable of flight, was conducted. The results indicate that autochthonous speciation, and not the occurrence of mainland relicts, explains these high endemic numbers. A regression analysis of log island area versus log number of Orthoptera species yields results similar to those of other plant and animal species. Faunistically rich land masses that lie within 20 km of one Channel Island are disproportionately more important as source areas than those land masses at distances exceeding 20 km. Simple regression of environmental components correlated with faunal diversity shows that for untransformed data, Orthoptera species numbers are significantly explained by area (82 %) and elevation (74 %). For log transformed data, the significance of area in explaining Orthoptera species number is diminished to 5700, while elevation explains 78 %, which is almost unchanged from before transformation. * Present address: David B. Weissman, University of California, Irvine, College of Medicine, Medical Student Affairs, Irvine, California 92717. Introduction Island biogeography, with its conceptual base largely laid by early works of Preston (1962) and MacArthur & Wilson (1963, 1967), is rapidly becoming an explicit, predictive portion of ecological theory. Insights into explanations of species distributions, community structure, and competitive interactions among species on islands come from many sources (see Diamond, 1973; Simberloff, 1974). Several such works (i.e. Diamond, 1969, 1971; Power, 1972; Lynch & Johnson, 1974; Hunt & Hunt, 1974; Johnson, Mason & Raven, 1968; Savage, 1967; von Bloeker, 1967) were specifically conducted on the California Channel Islands (see Fig. 1). These islands are particularly useful for testing many biogeographical tenets because only eight islands are involved: the Channel Islands are closer, fewer, and smaller than other island groups (i.e. Hawaiian, Galapagos, Canary, West Indies, etc.) from which extensive empirical biogeographical data have also come. Additionally, all eight Channel Islands are presently located near the mainland. This permits identification and comparison of island and mainland (source) faunas and assessment of probable speciation patterns. Also, the four northern (San Miguel, Santa Rosa, Santa Cruz, and Anacapa) and four southern (San Nicolas, Santa Catalina, San Clemente, and Santa Barbara) islands are themselves cohesive subgroups with reference to (i) geological similarity (see below) and (ii) gradients of size (and corresponding topographic diversity) and isolation (see Table 2). This paper is the first to present a comprehensive zoogeographical analysis of any insect group (specifically the Orthoptera) found on the Channel Islands. Six years (1969-74) of extensive field work on all the Channel Islands and adjacent mainland areas form the foundation for this analysis. Detailed census methods and complete species list are presented elsewhere (Rentz & Weissman, 1973, 1976).

Transoceanic Dispersal and Plate Tectonics Shaped Global Cockroach Distributions: Evidence from Mitochondrial Phylogenomics

Abstract Following the acceptance of plate tectonics theory in the latter half of the 20th century, vicariance became the dominant explanation for the distributions of many plant and animal groups. In recent years, however, molecular‐clock analyses have challenged a number of well‐accepted hypotheses of vicariance. As a widespread group of insects with a fossil record dating back 300 My, cockroaches provide an ideal model for testing hypotheses of vicariance through plate tectonics versus transoceanic dispersal. However, their evolutionary history remains poorly understood, in part due to unresolved relationships among the nine recognized families. Here, we present a phylogenetic estimate of all extant cockroach families, as well as a timescale for their evolution, based on the complete mitochondrial genomes of 119 cockroach species. Divergence dating analyses indicated that the last common ancestor of all extant cockroaches appeared ˜235 Ma, ˜95 My prior to the appearance of fossils that can be assigned to extant families, and before the breakup of Pangaea began. We reconstructed the geographic ranges of ancestral cockroaches and found tentative support for vicariance through plate tectonics within and between several major lineages. We also found evidence of transoceanic dispersal in lineages found across the Australian, Indo‐Malayan, African, and Madagascan regions. Our analyses provide evidence that both vicariance and dispersal have played important roles in shaping the distribution and diversity of these insects.

Studies in Australian Katydids: A Review of the Australian Snub-nosed Sylvan katydids (Tettigoniidae; Pseudophyllinae; Simoderini)

The Australian members of the simoderine katydids are reviewed. The tribe is known from nine genera, five of which occur only in Madagascar, the others are Australian: Chloracantha Hebard (C. lampra, C. angularis sp. nov., C. garradunga sp. nov., C. hilleri sp. nov.), Tallebudgeroptera gen. nov. (T. spininota sp. nov.), Mastigaphoides Weidner (M. haffneri, M. tuberculatus sp. nov., M. vaginalis sp. nov., M. lewisensis sp. nov.), Narea Walker (N. compacta, N. elongata, N. kungaree sp. nov.). Mastighapha Karsch is synonymised with Narea. Descriptions, illustrations, sound recording information and distribution maps are presented for all species.

Sound production in an Australian cockroach, Megazosteria patula (Walker) (Blattodea: Blattidae: Polyzosteriinae)

The large, diurnal Australian cockroach, Megazosteria patula (Walker), produces a sound when disturbed. The sound was found to be a form of stridulation caused by the rubbing of pegs on the underside of the thoracic segments against a ridge on the following segment.

Studies in Australian Tettigoniidae: A review of the Australian katydids of the genus Goodangarkia (Tettigoniidae: Conocephalinae; Agraeciini; Liarina)

Six species in Goodangarkia are described. Information on the distribution. ecology and cytology of species is presented. An unusual characteristic of cranial stridulation of one species is noted. Cytological evidence suggests the chromosome complement of species are more basal than those from Africa for example.