Sulabanus, Dvorak, Milan & Bocak, Ladislav, 2007

Dvorak, Milan & Bocak, Ladislav, 2007, Sulabanus gen. nov., a new genus of Lycidae (Coleoptera) from Sulawesi, Zootaxa 1611, pp. 1-24 : 3-6

Genus Sulabanus gen. nov.

Type species. Sulabanus mamasensis sp. nov.

Diagnosis. Sulabanus is the only lycid genus in Sulawesi with only four elytral costae, dense transverse elytral costae and non–lanceolate type of genitalia (Figs. 15–62).

Sulabanus resembles, in general appearance, the Afrotropical and Asian genus Xylobanus which is represented in Sulawesi by a few species. They share four primary elytral costae, the absence of secondary costae, seven areolae on the pronotum and serrate antennae in both sexes. They differ in the structure of male genitalia which are morphologically much more diversified in Sulabanus (Figs.15–62) and simply lanceolate in Xylobanus ( Bocak 2002) . The internal sac of Xylobanus bears a pair of sickle shaped sclerotized supporting structures and these are absent in all Sulabanus . Unlike Xylobanus , which has a close relationship to Cautires Waterhouse, 1879 , Sulabanus shares a similarly shaped pronotum, internal sac, and partly sclerotized membrane of the phallobase with several Australian metriorrhynchine genera such as Metriorrhynchus and Cautiromimus . The membership of Sulabanus in the Sulabanus , Porrostoma and Metriorrhynchus clade is supported also by molecular phylogenetic analysis ( Bocak et al. 2006, where three species of Sulabanus in the analysis were designated as “Metriorrhynchini gen. sp”.). Porrostoma is closely related to Metriorrhynchus , and Metriorrhynchus was considered a junior synonym of Porrostoma by Calder (1998). Sulabanus was placed as a sister group of Metriorrhynchus sensu Bocak (1998) , or as a sister group of Metriorrhynchus + Porrostoma in various analyses ( Bocak, 2006).

Description. Body slender, prothorax narrower frontally, mesothorax, metathorax and elytra parallel– sided, whole body slightly dorso–ventrally flattened ( Fig. 1 ). Coloration variable, pronotum and elytra concolorous light brown to black, with yellow transverse strip in humeral third of elytra in some species, dark with lighter humeral part of elytra in others. Head black, mouthparts light brown, ventral part of thorax yellow or dark brown to black, abdomen black, trochanters and bases of femora often light brown, other parts of legs regularly black.

Head hypognathous, slightly transverse, narrower than anterior margin of pronotum, partly hidden by pronotum, without rostrum ( Fig. 2 ). Labrum about as long as wide, emarginate at apex ( Fig. 4 ). Mandible slender, curved, without teeth in incisor part ( Fig. 8 ). Maxilla with fused galea and lacinia ( Fig. 7 ), maxillary palpus 4–segmented, apical palpomere parallel–sided to slightly securiform. Labium small, without ligula, with only few setae at apex ( Fig. 5 ), labial palpus 3–segmented, apical palpomere similar in shape to maxillary one. Antenna slender, flattened, reaching to elytral midlength or apical third, weakly to acutely serrate from antennomere 3, apical antennomeres narrower, parallel–sided or their apical part one tenth wider than base ( Fig. 7 ). Scape pear–shaped, robust, about twice longer than wide, pedicel small, more than two times wider than long, antennomeres 3–10 gradually slenderer to apex, antennomere 11 long, slender, about four times longer than wide. Antenna densely pubescent; similar in both sexes. Pronotum flat, 1.06–1.46 times wider than long. Anterior margin projected frontally, weakly emarginate in middle, lateral margins straight to weakly concave, basal margin bisinuate. Seven distinct areolae on disc ( Fig. 10 ), four attached to frontal margin, one median and two postero–lateral. Median areola slender, connected with frontal margin of pronotum by short to moderately long keel, basally attached directly to posterior margin. Lateral and/or median keels frontally often weaker to inconspicuous. Prosternum transverse, slender, prosternal process short ( Fig. 11 ). Scutellum small, deeply to widely emarginate at apex ( Fig. 9 ). Elytra parallel–sided, flat, weakly sclerotized, 2.4 to 4.0 times longer than width at humeri ( Fig. 12 ). Each elytron with four straight primary costae and numerous transverse costae which form elytral cells between them. All longitudinal costae similar in height and width and about equal in length. Transverse costae dense, only slightly weaker than longitudinal ones, elytral cells strongly transverse in most species, their bottoms only with dense microsetae. Both longitudinal and transverse costae with dense, short, moderately erect pubescence. Abdomen narrow, slightly shorter than elytra, with very soft cuticle. Male terminal segments slender, narrowing to apex (Figs. 66–67). Legs slender, compressed, with dense short pubescence ( Figs. 13–14 ).

Male genitalia derived from trilobate type, parameres absent, phallobase and phallus well developed. Phallus strong, straight; circular phallobase with partly sclerotized membrane in most species. Phallus widened at middle or apical part, short and robust or slender (Figs. 15–62). Internal sac at least partly sclerotized. Ovipositor with plate like, separate coxites; rod–like paraproctal baculi freely attached to coxites or fused with them; styli short, freely movable, connected with coxites by extensive membrane. Vagina simple, sac–like, membranous, with two lateral accessory glands attached distally. Spermathecal duct short, slightly spirally curved. Spermatheca simple, moderately sclerotized, globular, apically bears y–shaped gland (Figs. 63–65).

Remarks. The species of Sulabanus are very uniform in general appearance and in most cases when pairs of specimens collected in copula were unavailable we were not able to associate the females with confidence with conspecific males. Differences in the external coloration are limited to the presence and/or absence of a yellow to yellow–white patch on the humeral third of elytra or to a lighter humeral part of elytra. Externally, although some species differ slightly in body shape or shape of antennomeres, only the eye size and frontal distance of eyes were found to be reliable for identification. Male genitalia are the principal source of diagnostic characters and they were used for definition of species groups. The female specimens cannot be placed to a species group unless associated with a male.

Ecology. Adults of Sulabanus occur in forest habitats from sea level to high mountain elevations (1900 m a. s. l.). The greatest species diversity occurs in montane forests at elevations around 1000 m. Adults are most often found sitting on leaves in lower forest strata. Like many other lycids, species of Sulabanus avoid dry, sunny places around noon and the greatest flight activity was observed in the morning and from late afternoon to early evening, usually under forest canopy and not in open areas. Larvae of Sulabanus and their feeding habits are unknown.

Species of Sulabanus collected in various biotopes formed aggregations with very similar appearing species of the metriorrhynchine genera Wakarumbia , Cautiromimus , and Broxylus and the platerodine genus Plateros Bourgeois, 1879 . Often several species were found in high numbers (50– 200 specimens in one place) on a single tree or small group of trees in the forest, when no specimen was collected hundreds of meters around the place where they aggregated.

The body shapes of species in these genera are very similar in appearance: they are slender, 5.5-8.0 mm long, and the coloration of all species is either black to dark brown or black with an extensive, transverse, light coloured patch across the humeral third of elytra. The light yellow patch across the elytra is a rare colour pattern in Lycidae but it is known in Sulawesi with the metriorrhynchine genera Cautiromimus and Broxylus and the platerodine genus Plateros (all Lycidae ), an unidentified genus of Cantharidae , and several species of moths (Lepidoptera). Although the hypothesis of multiple origins of the transverse patch in elytra was not tested, high similarity of color patterns of some species placed in different genera, families and orders suggests Müllerian evolution of mimicry. All lycids have a detectable odor ( Moore & Brown 1981 and personal field observation in case of Sulabanus ) and mimicry rings with Lycidae as an unpalatable model were described by Lawrence and Britton (1991) and Lindsley (1961).

Zoogeography. Sulabanus is endemic to Sulawesi. The high species–level endemicity in Sulawesi is also known in other widespread lycid genera occurring in Sulawesi. Almost all lycid species that occur in Sulawesi are endemic to the island according to the present knowledge (with Metriorrhynchus thoracicus being the only species known from Sulawesi and the Molucca Islands; Bocak 1999, 2000, Bocak & Matsuda 1998, Bocak & Jass 2004, Bocakova 2006). The genera Sulabanus , Broxylus and Wakarumbia are endemic to Sulawesi. All species from these genera were collected exclusively in shaded under–canopy situations. In comparison all four metriorrhynchine genera whose species occur in disturbed and dry habitats ( Metriorrhynchus , Microtrichalus , Diatrichalus , and Leptotrichalus ) are known from extensive ranges from Australia and/ or the Molucca Islands to Indochina ( Kleine, 1933, Bocak, 2002, Bocak et al. 2006).

The material studied was collected in three separate mountainous areas of Sulawesi: northern (Dumonga– Bone National Park, Gn. Ambang Forest Reserve), the mountain area of central Sulawesi (northwestern area - Pendolo, Amporiwo, southern area - Sabbang, western area - the Mamasa valley), and southern (the Lompobatang massif). Although localities are few it appears that most species have very restricted ranges. Only a few species, S. lineatus , S. brunneus , S. gracilis , and S. major were collected in two or three localities, but almost all of them were still restricted to a single mountainous area in the central part of Sulawesi. All of the remaining species are known from a single valley, volcano or other small range. Until now, no species collected in Northern Sulawesi Province by the one–year British expedition was found in the Central or Southern Sulawesi Provinces, although these collections were large in number of specimens and number of species.

The distribution of species groups is not restricted to the individual mountain ranges and their representatives are known from geographically distant localities, which are separated by lowlands or the sea. The S. mamasensis and S. utarensis groups are known from central and northern Sulawesi; S. pendolensis and S. major groups are known from the whole island.

Figures

FIGURES 1 – 14. Sulabanus ulci 1 – general appearance; 2 – head; 3 – antennae; 4 – labrum; 5 – labium; 6 – hypopharynx; 7 – Maxilla; 8 – Mandible; 9 – Scutellum; 10 – Pronotum; 11 – prosternum; 12 – elytra; 13 – hind leg; 14 – tarsus. Scale 0.5 mm (Figs. 1 – 3, 10 – 14), 0.25 mm (Figs. 5, 7), 0.1 mm (Figs. 4, 6, 12).