Larval Characteristics and Generic Placement of Endemic Hawaiian Hemerobiids (Neuroptera)l

The brown lacewings (Neuroptera: Hemerobiidae) have undergone a spectacular radiation on the Hawaiian Archipelago; currently 23 endemic micromine species are recognized, 19 of which were described by Perkins and four by Zimmerman. Recent systematics studies, using adult morphological characteristics, placed these lacewings in the cosmopolitan genus Micromus. Two of the Hawaiian species (Micromus vagus [from Hawai'i and Maui] and M. rubrinervis [from Hawai'i)) exhibit larval characteristics indicating a close relationship with Micromus. Both species have more larval traits in common with Micromus than with other hemerobiid genera. However, until larvae from the three other genera in Microminae become available, it is not possible to designate whether any of these larval traits are synapomorphic for Micromus. The results also indicate that phylogenetic analyses of the Hemerobiidae should include all instars and that interspecific comparisons should be made on equivalent semaphoronts. OUR STUDY FOCUSES on one of Hawai'i's most diverse and fascinating groups of predatory insects, the endemic micromine brown lacewings (Neuroptera: Hemerobiidae). R. C. L. Perkins pioneered in the collection and systematic study of Hawaiian hemerobiids. He described 23 species, which were grouped into three new genera (Perkins 1899, 1910). Nineteen of these species remain recognized, and they include some with heavily scalloped wings, as well as flightless species with coriaceous forewings and rudimentary or no hind wings. Subsequent to Perkins' work, E. C. Zimmerman added four new species and compiled a comprehensive review of the group (Zimmerman 1957). Both Perkins and Zimmerman recognized numerous similarities between the endemic Hawaiian 1 This project was funded in part by Regional Research Project W-185, the Undergraduate Fellowship Program of the Pew Charitable Foundation, the National Geographic Society (Research Committee), the CALS Office for Research, Cornell University (Morley Grant for Undergraduate Research and CALS Charitable Trust), and the Grace H. Griswold Fund (Department of Entomology, Cornell University). This is contribution no. 1996-024 of the Hawai'i Biological Survey. Manuscript accepted 3 February 1997. 2 Department of Entomology, Comstock Hall, Cornell University, Ithaca, New York 14853 (address for correspondence); also Research Associate, Bernice P. Bishop Museum, Honolulu, Hawai'i. J Cornell University, Ithaca. New York 14853. micromine species and the cosmopolitan genus Micromus (Perkins 1899, Zimmerman 1957), but they allocated the species among three genera, Nesomicromus, Pseudopsectra, and Nesothauma. More recently, all 23 species of micromine hemerobiids endemic to Hawai'i were included in Micromus (Monserrat 1990, Oswald 1993). No study has examined whether the Hawaiian micromine lineage is monophyletic. Almost all previous systematic work on hemerobiids is based exclusively on the adult stage, and knowledge of hemerobiid larvae is generally poorly developed. Nevertheless, some detailed descriptions of hemerobiid larvae exist (e.g., Killington 1936, 1937, 1946, MacLeod 1960), and syntheses of the scattered larval descriptions are beginning to emerge (MacLeod 1960, Veenstra et al. 1990, Krakauer and Tauber 1996). These investigations indicate that the comparative morphology of the larvae will contribute substantially to the overall systematic analysis of the group (e.g., see MacLeod 1960, Krakauer and Tauber 1996). Krakauer and Tauber (1996) described a suite of traits that distinguishes Micromus larvae from those of seven genera representing six subfamilies other than Microminae. Larvae in these seven genera share many of the traits expressed