Tenebroides (Polynesibroides), Kolibáč & Bocakova & Liebherr & Ramage & Porch, 2021

Kolibáč, Jiří, Bocakova, Milada, Liebherr, James K., Ramage, Thiboult & Porch, Nick, 2021, Extinct and extant Pacific Trogossitidae and the evolution of Cleroidea (Coleoptera) after the Late Triassic biotic crisis, Zoological Journal of the Linnean Society 191 : -

ORIGIN OF POLYNESIBROIDES AND PARALLELODERA

The species-rich genus Tenebroides is distributed worldwide, with the largest diversity of species in South and Central America (more than 150 species; Kolibáč, 2013) and with a few species autochthonous in the Canary Islands [ T. latens ( Wollaston, 1862) , T. rectus ( Wollaston, 1862) ], Europe [‘ T. fuscus (Goeze, 1777) ’ which perhaps represents natural populations of T. mauritanicus ; Kolibáč, 1993, 2013], North Africa ( T. maroccanus ) and Central Asia ( T. turkestanicus Ballion, 1870 ). The presently cosmopolitan T. mauritanicus likely has a West Palaearctic origin, indicated by European archaeological records (e.g. King et al., 2014; two specimens from a 14 th century Czech settlement housed in MMBC). Two Cenozoic species have been described from European deposits and a third from the Middle Palaeocene of Greenland ( Kolibáč, 2013). Molecular analysis reveals Polynesibroides is a part of Tenebroides with a sister-group relationship to a single species in Panama and morphological analysis as a sister-group of Parallelodera , including the Panamanian (and Colombian) species. However, although our analyses suppose a sister relationship for both groups, we have not enough molecular or morphological data to exclude relation of Parallelodera and Polynesibroides to some other American species-groups among the highly diversified continental Tenebroides .

Following the results of both analyses, there are two competing hypotheses on Parallelodera + Polynesibroides dispersal, both supposing an American origin and dispersal of their common ancestor westwards. The first one proposes that both subgenera spread independently: Parallelodera colonized the westernmost region ( New Caledonia, Fiji, Tongatapu), while Polynesibroides colonized the Society, Cook and Austral Islands ( Fig. 15). Parallelodera includes the previously mentioned continental species and its members possess a number of ancestral character states, especially fully developed metathoracic wings and the ability to fly. The second hypothesis suggests repeated eastwards dispersal of the advanced Polynesibroides derived from a Parallelodera ancestor. An original distribution of Parallelodera could have been wider in the past, as indicated by the presence of Tenebroides parallelus in Tahiti (Society Islands) and Nuku Hiva (Marquesas Islands).

American affinities have also been indicated in several Polynesian lineages, such as Havaika jumping spiders ( Arnedo & Gillespie, 2006) and Misumenops crab spiders ( Garb & Gillespie, 2006), and both air and ocean currents could have served as means of colonization of the central Pacific from either direction ( Jokiel & Cox, 2003; Gillespie et al., 2008). Nevertheless, a deep estimated Polynesibroides divergence (~41 Mya), in comparison with the low geological age of the Society Islands (4.5 Myr; Uto et al., 2007) and most other Pacific islands ( Neall &Trewick, 2008), complicates interpretation of the evolution of the Tahitian Polynesibroides . It seems likely that this estimate may reflect the fact that the closest New World relatives of the south-eastern Polynesian Tenebroides lineages are not currently included in the molecular tree.

Although most of the biota of the Society Islands is younger than the geological age of the archipelago (4.5–0.6 Myr; Blais et al., 2000; Neall & Trewick, 2008), several lineages presently distributed on the Society Islands apparently colonized eastern Pacific islands before the Society archipelago was established ( Hembry & Balukjian, 2016), because many Polynesian islands are older than the Society archipelago. Particularly, the Cook–Austral islands (e.g. Raivavae 6.5 Myr and Atiu 8 Myr; Neall & Trewick, 2008) and the Tuamotu archipelago, originally high, volcanic islands at or near the East Pacific Ridge ( Patriat et al., 2002) are of much greater age, dated to> 50 Myr ( Schlanger, 1984). Therefore, the first hypothesis of the colonization of south-eastern Polynesia by Polynesibroides in a westward direction is plausible. Conversely, support of a scenario suggesting dispersal of a Polynesibroides ancestor from the west back to the east would require additional material from across the Pacific Ocean.

Phanodesta Reitter, 1876 ( Trogossitidae : Gymnochilini ) is an interesting example of a recently disjunct Pacific distribution within Trogossitidae .

a T. rimatara : two elytra measured.

b Approximate width between anterior/posterior corners of pronotum.

c From base to outer corner of intercoxal process apex.

d From base of intercoxal process to very end of cavity (outer tip of trochantin) /from very end of cavity to outer corner of intercoxal process apex.

e Line extending elytral base in its articulation (angle) with condyle /line extending the ninth stria in its basal third.

Eleven species are known from New Zealand, four from New Caledonia, one from Lord Howe Island and six apterous species from the far-removed Juan Fernandez Islands in the eastern Pacific ( Leschen & Lackner, 2013). The single Asian species has been recently described from Sulawesi ( Yoshitomi, 2014). This example shows a great dispersal potential in the trogossitids and, therefore, the possibility of an origin of the ancestor of Polynesibroides and Parallelodera in America, where the centre of distribution of both subgeneric relatives lies.

Two other adaptive radiations of plant-associated Coleoptera are also centred on archipelagos in the southern Pacific Ocean. Rhyncogonus Sharp, 1885 weevils ( Curculionidae : Entiminae ) have colonized and diversified in the Cook and Austral, Society and Marquesas Island systems of the southern Pacific, with the Society Island lineage colonizing the Hawaiian Islands of the mid-Pacific region ( Samuelson, 2003; Claridge et al., 2017). Small, isolated islands have also been colonized. Single Rhyncogonus species are known from the Kermadec Islands and Pitcairn Island, and three species are distributed from Wake Island through the Line Islands ( Samuelson, 2003). The immediate sister-taxon of Rhyncogonus – members of the weevil tribe Elytrurini – are distributed from the Solomon Islands to Tonga and Samoa, and the secondary outgroup to both Rhyncogonus and the elytrurine weevils – the tribe Celeuthetini – is broadly distributed across Indonesia, the Philippines, New Guinea, tropical north-east Australia and westward, including the southern Pacific archipelagos occupied by Rhyncogonus ( Claridge et al., 2017) . Thus, the historical biogeographic connections of Rhyncogonus lie to the west in Asia and Australia, although this monophyletic genus has radiated in the southern Pacific over the past 15 Myr ( Claridge et al., 2017). Rhyncogonus larvae are internal stem and root borers, and so the dispersal mechanism allowing colonization of such isolated island systems likely involved rafting on mats of plant debris ( Carlquist, 1965), possibly generated via tropical storms or massive landslides associated with earthquake-shed volcanic material ( Moore et al., 1989). However, the role of seabirds cannot be excluded in Rhyncogonus dispersal ( Samuelson, 2003). The curculionoid subfamily Oxycoryninae (Belidae) includes the species-rich genus Proterhinus Sharp, 1878 , which has radiated extensively on the Hawaiian Islands with 161 species described to date ( Perkins, 1900; Nishida, 2002). Proterhinus have also been described from Samoa ( Perkins, 1906), the Marquesas Islands ( Perkins, 1932) and the Society Islands (Tahiti, Mo’orea, Taha’a) and Rurutu of the Austral Islands ( Zimmerman & Perrault, 1989). Proterhinus is the sister-genus to Aralius Kuschel, 1990 , which comprises species distributed in New Caledonia and New Zealand ( Marvaldi et al., 2006). These two genera are in turn the adelphotaxon to Aglycyderes Westwood, 1864 , a genus with one species distributed in the Canary Islands plus a second in Morocco. That this disjunct biogeographic pattern is relictual is supported by the presence of fossil Belidae in the Late Jurassic Yixian Formation of China ( Ming et al., 2006). Proterhinus weevils are associated with dead and dying woody plant parts, often from limited ranges of hosts ( Perkins, 1928; Swezey, 1954). Proterhinus larvae may occur under bark, inside dead and dying twigs and branches, or as leaf miners ( Anderson, 1941; Swezey, 1954). Hence, much like Rhyncogonus , the overwater movement of plant materials likely explains the broad geographic distribution of Proterhinus across significant portions of the Pacific.

Thus, even though Tenebroides tahiti adults differ from Rhyncogonus and Proterhinus species by being surface or subcortical dwelling predators, they are, like those internally feeding herbivores or fungivores, intimately associated with plants, and potentially protected from the vicissitudes of oceanic dispersal across salt water, while being secreted within floating mats of plant debris. That speciation has proceeded among the various south-eastern Polynesian Tenebroides spp. , both extant and extinct, across the various southern Pacific archipelagos points to the rarity of such overwater dispersal events. Much like the sequence of events hypothesized for Rhyncogonus ( Claridge et al., 2017) , rare but persistently occurring dispersal events provide the means to access on remote islands, while maintaining the temporal isolation required to allow speciation to proceed, i.e. diversification to occur, within those archipelagos. That Tahitian Tenebroides spp. have a somewhat more limited geographic distribution in the Pacific, especially based on distributions of the extant species, may be due, in part, to their occupation of a higher trophic level within the island-based ecosystems.