New Mecyclothorax spp. (Coleoptera, Carabidae, Moriomorphini) define Mont Mauru, eastern Tahiti Nui, as a distinct area of endemism

Abstract

Seven species of Mecyclothorax Sharp precinctive to Mont Mauru, Tahiti, Society Islands are newly described: Mecyclothorax tuteisp. n., Mecyclothorax tihotiisp. n., Mecyclothorax putaputasp. n., Mecyclothorax toretoresp. n., Mecyclothorax anaanasp. n., Mecyclothorax pirihaosp. n., and Mecyclothorax porosp. n. These seven constitute the first representative Mecyclothorax species recorded from Mauru, and their geographic restriction to this isolated massif defines it as a distinct area of endemism along the highly dissected eastern versant of the Tahiti Nui volcano. Each of the new species has a closest relative on another massif of Tahiti Nui, supporting speciation associated with vicariance caused by extensive erosional valley formation, especially the development of Papenoo Valley. Comparison of the known elevational distributions of the new discoveries on Mont Mauru to the elevational diversity profile of the comparatively well-sampled Mont Marau, northwest Tahiti Nui, suggests that numerous Mecyclothorax species remain to be discovered in higher-elevation habitats of Mont Mauru.

Keywords: French Polynesia; allopatric speciation; biodiversity; biogeography.

Figure 1.

Massifs of the Tahiti Nui and Tahiti Iti volcanos, Tahiti, Society Islands (redrawn and amended from Perrault 1992). Massifs indicated were either sampled by Perrault (1978a et seq.) or during 2006 field work supporting the current study. Dashed lines indicate lowland valleys and associated headlands below 1000 m elevation that separate major massifs.

Figure 2.

Habitats within which specimens of Mecyclothorax spp. were collected A Lava tube at 705 m elevation on Faatautia River drainage; holotype of Mecyclothorax poro collected by pyrethrin fogging vegetation growing on rocky bank between Dr. Curtis Ewing and climbing rope near edge of waterfall B Bank of Dicranopteris and Blechnum ferns at 1010 m elevation on Mont Mauru pylon trail; fern bank treated with pyrethrin fog by Dr. Dan Polhemus resulting in specimens of Mecyclothorax anaana and Mecyclothorax pirihao C Pyrethrin fog sheet apparatus around moss-covered Metrosideros trunk in low stature, open-canopy, wet rain forest at 1060–1110 m elevation, Mont Mauru, by which specimens of Mecyclothorax tihotii and Mecyclothorax putaputa were collected; trees did not exceed 4m height, mossmats were as thick as 15 cm

Figure 3.

Mecyclothorax spp., dorsal view; small silhouette indicates actual size of beetle specimen at printed journal page size A Mecyclothorax tutei female holotype B Mecyclothorax tihotii male holotype C Mecyclothorax putaputa female paratype (CUIC)

Figure 4.

Mecyclothorax spp., dorsal view; small silhouette indicates actual size of beetle specimen at printed journal page size A Mecyclothorax toretore female holotype B Mecyclothorax anaana male paratype (CUIC) C Mecyclothorax pirihao male paratype (CUIC) D Mecyclothorax poro female holotype

Figure 5.

Male aedeagal median lobe and associated parameres, Mecyclothorax spp.; all figures to same scale A Mecyclothorax tihotii, right lateral view B Mecyclothorax tihotii, euventral view C Mecyclothorax anaana, right lateral view D Mecyclothorax pirihao, male dissection 1, right lateral view E Mecyclothorax pirihao, male dissection 2, right lateral view Abbreviations: fp flagellar plate lp left paramere of ostial flap rp right paramere vmf ventral microtrichial field.

Figure 6.

Female reproductive tract dissections, Mecyclothorax spp., ventral view; figures to same scale A Mecyclothorax tihotii B Mecyclothorax anaana C Mecyclothorax pirihao Abbreviations: bc bursa copulatrix co common oviduct dg defensive fland reservoir gc1 basal gonocoxite 1 gc2 apical gonocoxite 2 hg rectum of hindgut sg spermathecal gland sp spermatheca. Position of spermathecal duct and juncture of duct with dorsal wall of bursa indicated by black line and terminal circle, respectively

Figure 7.

Female left gonocoxite, Mecyclothorax spp., ventral view A Mecyclothorax tihotii B Mecyclothorax anaana C Mecyclothorax pirihao. Abbreviations: afs apical fringe setae ans apical nematiform setae des dorsal ensiform seta gc1 basal gonocoxite 1 gc2 apical gonocoxite 2 les lateral ensiform setae r ramus.

Figure 8.

Exposed gonocoxae and apical visible ventrite of Mecyclothorax holotype females, ventral view; four setae comprising median setal patch on female apical visible ventrite indicated by asterisks; number of apical fringe setae (afs) of basal gonocoxite 1 indicated in parentheses A Mecyclothorax tutei B Mecyclothorax putaputa C Mecyclothorax toretore

Figure 9.

Elevational distributions of species found on Mont Marau, northwest Tahiti Nui (●) and Mont Mauru, eastern Tahiti Nui (○); elevational ranges indicated by vertical “barbells.” Sloping red line connects GPS-associated collecting localities along Marau summit road recorded during 2006 collecting activities. Sloping blue line connects GPS-associated localities along pylon trail ascending Mauru. Kilometer marks for these transects reflect direct map distances. Horizontal blue line indicates maximal 1110 m elevation achieved during 2006 collecting activities on Mauru. Horizontal black line indicates summit elevation of Mauru. Species from Mauru include: 1 Mecyclothorax poro 2 Mecyclothorax pirihao 3 Mecyclothorax anaana 4 Mecyclothorax tutei 5 Mecyclothorax toretore 6 Mecyclothorax tihotii 7 Mecyclothorax putaputa.