Plateros Bourgeois, 1879

Tvardik, David & Bocak, Ladislav, 2001, Review of the genus Plateros Bourgeois (Coleoptera; Lycidae) from Sulawesi, Zootaxa 16, pp. 1-12 : 2-4

Plateros Bourgeois, 1879

Plateros Bourgeois, 1879: 19 .

Type species: Plateros brasiliensis Lucas, 1857 (by subsequent designation)

Diagnosis. Antennomere 3 broader and at least slightly longer than antennomere 2, pronotum without carinae, median longitudinal line channelled basally, forming minute areola at posterior margin, each elytron with 9 weak longitudinal costae connected by transverse costae, male genitalia without paramerae, ovipositor short, length of valvifers similar to those of coxites.

Sexual dimorphism. Males and females differ mostly in the relative size of eyes, females having almost regularly eyes much smaller than interocular distance. If male antennae are serrate or flabellate, then female antennae are much slenderer, without or with minute antennomeral processes.

Distribution. Worldwide distributed genus, known from all zoogeographical regions and many oceanic islands, absent in New Zealand and Hawaii. The highest diversity is known from tropical rain forests of the Oriental Region.

Ecology. The Sulawesi Plateros species were collected in the lower mountain forests in the west Toraja region (Mamasa valley) and on the northern slope of the Lompobatang massif in the southernmost tip of Sulawesi (elevations 1100­1800 m a. s. l.). Adults were slowly moving or sitting on leaves of shrubs and trees of the lower forest canopy stratum. They were only seldom flying during day light and usually were not disturbed even by shaking branches. Larvae of Sulawesi Plateros are unknown, but the development in rotting wood is expected as in relative species in neighbouring regions.

Lycids are protected from predators by the presence of several odour and bitter compounds ( Moore & Brown 1981), and therefore they have a very strong tendency to form mimicry complexes. Unlike Sulawesi species, Plateros from other regions are often brightly coloured and their body is often wider. The Sulawesi species can be divided in two groups considering general appearance. Plateros flavidus , P. t o l i e n s i s nom. n., and P. lalui sp. n. are brightly yellow coloured and their body is slightly wider. They remind unrelated genera Microtrichalus Pic, 1930 ( Metriorrhynchinae , Trichalini), Cautiromimus Pic, 1926 (Metriorrhynchini) , and undescribed genus of Lyropaeini ( Leptolycinae ) occurring in the same area. The second group is characterised by the slender, black body. They remind in general appearance several syntopically occurring Wakarumbia Bocak, 1999 ( Metriorrhynchinae , Hemiconderina), Xylobanus Waterhouse, 1879 , and Broxylus Waterhouse, 1879 (Metriorrhynchini) . The silver pubescence well developed in most black Sulawesi Plateros is similar to those in several species of Wakarumbia and Xylobanus from the same area. Such pubescence has not been found in lycids from other regions and its coevolution in unrelated groups of lycids shows possible selective pressure from predators.

Species level relationships. The Sulawesi Plateros species are uniform in most external characters. We found variability in the shape of male genitalia ( Figs 1­13 ), shape of antennae ( Figs 20­27 ), and relative size of eyes. Male genitalia support closer relationships between P. milenae sp. n., P. rubromamasensis sp. n. and P. mamasensis sp. n. They share the sclerotized plate in internal sac ( Figs 3­6 , 11 ). Additionally P. rubromamasensis sp. n. and P. mamasensis sp. n. posses a shallow groove in the dorsoapical part of phallus ( Figs 3 , 11 ). On the other side, the antennomere 3 of P. milenae sp. n. and P. rubromamasensis sp. n. is very similar in shape ( Figs 24, 26 ) and differs from the serrate antennomere 3 in P. mamasensis sp. n. Both small and large eyes were found in this group. Already previous studies (e. g. Bocakova 1997a, b) showed that eye size is variable within species groups and we expect that the eyes size is correlated with night flight activity.

P. kalamensis sp. n. and P. orobuensis sp. n. share very slender antennae with parallelsided antennomeres 3­10 ( Figs 21­25 ). Their male genitalia are characteristic in a very slender phallus and membranous internal sac ( Figs 7­10 ). The similar shape of the phallus is found in P. tanatorajensis sp. n., which differs in acutely serrate antennae ( Fig. 27 ).

The males of P. flavidus and P. toliensis nom. n. are unknown and therefore their relationships with newly described species remain unclear. They differ in serrate female antennae from dark coloured species and from P. lalui sp. n., which is the closest species considering body shape and colouration. The serrate female antennae are usually present in Plateros species with flabellate male antennae. Males are necessary for the clarification of the relationships and for accurate identification of these species.

Figures

FIGURES 1 ­ 10: Male genitalia. 1 ­ 2: Plateros kalamensis sp. n.; 3 ­ 4: P. m a m a s e n s i s sp. n.; 5 ­ 6: P. milenae sp. n.; 7 ­ 8: P. orobuensis sp. n.; 9 ­ 10: P. tanatorajensis sp. n. Scale 0.5 mm.

FIGURES 11 ­ 27. 11 ­ 13: Male genitalia. 11: Plateros rubromamasensis sp. n.; 12 ­ 13: P. lalui sp. n.; 14 ­ 19: Male pronota. 14: P. kalamensis sp. n.; 15: P. mamasensis sp. n.; 16: P. milenae sp. n.; 17: P. orobuensis sp. n.; 18: P. rubromamasensis sp. n.; 19: P. tanatorajensis sp. n.; 20: Female antenna. 20: P. flavidus Kleine, 1933; 21 ­ 27: Male antennae. 21: P. kalamensis sp. n.; 22: P. lalui sp. n.; 23: P. mamasensis sp. n.; 24: P. milenae sp. n.; 25: P. orobuensis sp. n.; 26: P. rubromamasensis sp. n.; 27: P. tanatorajensis sp. n. Scale 0.5 mm.