The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of West Maui, Hawaii: taxonomy, biogeography, and conservation

Abstract

Species of the genus Mecyclothorax Sharp are taxonomically revised for West Maui, resulting in recognition of 27 species, 23 newly described: M. allostriatus, M. arcanus, M. badius, M. bartletti, M. ceteratus, M. clermontiae, M. curtimutinus, M. excavatus, M. exilioides, M. ferovipennis, M. filitarsis, M. geminatus, M. improcerus, M. kahalawaiae, M. lyratus, M. minimops, M. oppenheimeri, M. pallidus, M. platops, M. scapulatus, M. ustulatus, M. vicinus, and M. vulcanoides. Among the species are two pairs of cryptic sibling species best diagnosed by male and female genitalia. In the sibling species pair M. lyratus and M. arcanus, the former species is geographically restricted to Hanaula, an isolated southern massif in West Maui, whereas the latter is distributed on the main massif, Puu Kukui. Mecyclothorax scapulatus is also restricted to Hanaula supporting recognition of this massif as a distinct area of endemism within the Mauna Kahalawai mountain system. Species comprising a second sibling species pair, M. allostriatus and M. geminatus, exhibit a mosaic geographic distribution wherein each locality supports only one species, but the species distributions interdigitate among the various isolated localities from which the two species are known suggesting a more complicated speciation history. The genus Mecyclothorax is treated as part of an austral assemblage of genera classified as the tribe Moriomorphini (stat. n.). Species richness and endemism are compared among West Maui carabid beetles, land snails (Gastropoda), and Drosophilidae (Diptera). Carabid beetles with 46 species present in West Maui are less rich than the land snail fauna of 59 species and drosophilid fly fauna of 51 species. Over all genera, carabid beetles exhibit 87 % species-level endemism to West Maui, with Mecyclothorax species 100 % precinctive. Percentage endemism across all snail groups is somewhat lower -73 % -but among the more diverse snail families Achatinellidae and Amastridae, fraction endemism is similar to beetles, being 80 % and 88 % respectively. Drosophilidae exhibit much lower levels of endemism, with only 25 % of West Maui species restricted to the volcano. Authochthonous speciation occurs at similar rates in all three groups, with species duration in all three groups estimated to be 0.2-0.3 Myr. The higher fraction endemism in beetles versus flies can be explained in part by absence of metathoracic flight wings in 48 of the 51 resident carabid species versus the retention of flight by the flies. Mecyclothorax species diversity peaks at 1200-1300 m elevation. This elevational zone supports closed canopy forest with a well-developed forest floor leaf litter microhabitat, enabling occupation by subarboreal trunk and moss inhabitants as well as terrestrial litter-inhabiting taxa. Mecyclothorax species are recorded in habitats ranging from 600m to the highest West Maui summit at 1760 m elevation. Their present-day persistence in this broad range of natural habitats makes them suitable subjects for habitat monitoring and c...

The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Tahiti, Society Islands

“…Based on the numbers of extant species, and the origins of their respective radiations via single colonization events on islands of known age (Liebherr 2012a), both the Society Island and Hawaiian Mecyclothorax radiations have been built up from ancestral species persisting an average of about 0.3 Myr (Table 4). These estimates are in line with 0.20–0.30 Myr species’ durations hypothesized using paleoclimatic data for Haleakala and West Maui sister-species pairs of Mecyclothorax , Drosophila , and land snails in the families Achatinellidae and Amastridae (Liebherr 2011). Somewhat longer species durations have been reported for Laupala crickets (Table 4; Mendelson and Shaw 2005; Sherrod et al 2007), and for cave-inhabiting Oliarus planthoppers (Wessel et al 2013), two monophyletic groups occupying Hawaii Island.…”

“…data) 2 Liebherr (2011) 3 Hardy (1965, 1966, 1977, 1978), Hardy and Kaneshiro (1968, 1969, 1971, 1972, 1975, 1979), Hardy et al (2001), Kaneshiro and Kambysellis (1999), Lapoint et al (2009), Magnacca and O’Grady (2008a, 2008b, 2009), Magnacca and Price (2012), O’Grady et al (2001, 2003a, 2003b), Perreira and Kaneshiro (1990); K.N. Magnacca (pers.…”

“…This paper follows directly the laboratory protocols presented in Liebherr (2009, 2011, 2012a). Those papers may be consulted for explanations of the procedures used to elucidate taxonomic characters of the various species.…”

The Mecyclothorax beetles (Coleoptera, Carabidae, Moriomorphini) of Haleakala-, Maui: Keystone of a hyperdiverse Hawaiian radiation

“…Specimen preparation and dissection protocols are the same as those used for prior Hawaiian Mecyclothorax revisions (Liebherr 2007, 2008b, 2009a, 2009b, 2011). Briefly, both male and female specimens were relaxed in nearly boiling distilled water held in shell vials placed in a double boiler, the water containing a drop of Kodak Photo-Flo® detergent.…”

“…Conversely, the genus is not represented on Kaua‘i, the oldest subaerial high island. Fitting with that absence, the O‘ahu Mecyclothorax fauna is attenuated, with only a few species groups and 20 species occurring on the island (Liebherr 2009a), whereas the present-day fragments of Maui Nui support more species—Moloka‘i with 43 (Liebherr 2007) and West Maui with 27 (Liebherr 2011)—complementing the great diversity of Haleakalā. The Mecyclothorax fauna of the geologically youngest island of Hawai‘i (Liebherr 2008b) comprises 30 species, all members of species groups that have diversified on Haleakalā.…”