Oxylopsebus, S., 2008

S., O., 2008, OXYLOPSEBUS BRACHYPTERUS: a new genus and species of Oxycoleini (Coleoptera, Cerambycidae, Cerambycinae) from Bolivia Robin O. S. Clarke ABSTRACT, Papéis Avulsos de Zoologia 48 (9), pp. 61-67 : 61-67

Oxylopsebus gen. nov.

( Fig. 1)

Type species: Oxylopsebus brachypterus sp. nov., by present designation.

Etymology: This new genus of Oxycoleini has been named to reflect its affinities to the Psebiini .

Sexually dimorphic abdomen and hind legs. Head prognathous, neck elongate, projecting head well forward of pronotum. Mandibles acuminate. Clypeus large, with sparse, shallow punctures near base, front margin straight, sides diverging to base, not well delimited from frons. Palps short, maxillary palps with basal palpomeres small and transverse, the apical one longer than the rest together, subcylindrical, its apex slightly acuminate. Fronto-clypeal suture absent; front of head wholly occupied by a very deep Y-shaped indentation, anteriorly curved and transverse, medially extending almost to superior lobes.

Eyes large and prominent, occupying two thirds of genae, strongly emarginate, superior lobes well developed, separated by twice their own width; eyes very finely faceted, 16-18 ommatidia per row at middle of superior lobes.

Antennal tubercles undeveloped, marked by a slightly convex, shining, impunctate area. Antennae with eleven segments, almost filiform, longer than body in male, reaching apical quarter of abdomen in female; segments not carinate, very finely pubescent; distinct, sparse setae on sides of scape, underside of pedicel third antennomere, and mesally on IV-VI; scape strongly curved, base narrow, apex broad, not reaching front margin of pronotum. Pedicel small and rounded, almost rudimentary. Antennomere III slightly shorter than scape, and slightly shorter than rest of flagellomeres, IV-VII the longest – half as long again as III in both sexes. In female VIII and IX short- er than IV-VII but distinctly longer than III, X and XI slightly longer than III. In male, VIII-XI subequal, shorter than IV-VII, distinctly longer than III.

Prothorax ( Fig. 2) subquadrate, narrowing towards apex. Pronotum smooth and shining, with smoothly rounded calli, as follows: i) two elliptical calli at centreline, one smaller and close to front margin, the other larger and behind middle, ii) paired sinuate calli to either side of centre, running from basal third (where they form the anterior lateral tubercles) to almost hind angles iii) sides of pronotum with large rounded calli at middle and iv) each basal angle overlayed by a narrow, prominent callus. Prosternum without sexual puncturation; prosternal process laminiform ( Fig. 3), apical half strongly expanded, posterior border variable, from truncate to doubly emarginate (giving it a trilobed appearance), passing well beyond coxal cavities; procoxal cavities closed behind, and angled at sides. Pro- and mesocoxae prominent. Mesosternal process ( Fig. 4) without tubercle, almost parallel sided, apex slightly excavate, apical angles acute, half the width of coxae; mesocoxal cavities open. Metasternum broad and convex.

Elytra strongly dehiscent, semi-translucent, shortened, reaching, or slightly surpassing, apex of first urosternite, subparallel at sides, apices acuminate. Humeri prominent, slightly rounded and projecting forwards. Elytra strengthened by a carina running from humerus to apex; epipleur reduced behind humerus, leaving metasternum visible from above.

Abdomen of female ( Fig. 5) wide at middle, with five visible urosternites. Urosternite I trapezoidal, convex, equal in length to II-IV combined, widest at apex and equal in width to II, wider than III and IV, IV narrower by one third, V half as wide ( III and IV may deform in dried specimens). Urosternite II transverse, width half as long again as length, apical margin deeply and regularly emarginate from sides to centre, where it is less than half as long as wide; sides weakly sclerotised, apical half with a transverse depression furnished with four types of hairs from front to hind edge, slender fine hairs of normal type on basal half and at sides, followed by three sorts of specialised hairs: i) a thick layer of long, stout, hairs with gobular tips bordering front edge of depression, ii) a narrow fringe of longer, recumbent hairs with conchoidal tips bordering hind edge of depression, iii) very long, thickened, curved hairs sprouting from centre and sides of depression. Urosternite III weakly sclerotised and somewhat irregular in form, divided into two transverse parts by a distinct carina bearing long fine hairs reaching apex of posterior half; hind edge excised and parallel to hind edge of II. Urosternite IV transverse with long hairs on all sides, thicker laterally, surface from almost sides to centre concave. Urosternite V transverse, depressed at centre, slightly excavate at apex, posterior margin with stout setae .

Abdomen of male ( Fig. 6) with six visible urosternites, subparallel, widest at middle. Urosternite I equal in length to II+ III combined, I-III truncate at apex. Hind border of urosternite IV slightly emarginate. Urosternite V distinctly narrower than I-IV, posterior border deeply and regularly emarginate. Urosternite VI narrower than V, rounded at sides, hind margin with deep U-shaped incision at middle. Parameres semi-fused, separated for apical third.

Legs moderately long, femoral peduncles long, claves large; front and middle legs subequal; hind legs the longest, greatly enlarged and strengthened, especially in female, not quite reaching apex of abdomen. Tibiae curved, lacking carina nor sulcate; protibia only slightly curved, slightly widening before apex, apex with small, inconspicuous mesal spine; mesotibia strongly curved, gradually widened to apex, apex with two small spines, the lateral one indistinct; metatibia distinctly curved, apex with two spines, the lateral one indistinct, the mesal one large. Tarsi subequal, tarsal pads developed, claws notably long, two thirds length of onychium, which is two thirds that of tarsomere I; first metatarsomere of equal length to II+ III, III narrow and deeply bilobed.

Discussion: For the purposes of this study I was able to examine specimens in the MZSP collection of the following genera: Obrium Dejean, 1821 , Luscosmodicum Martins, 1970 , Nathrius Bréthes, 1916 , Paraleptidia Gounelle, 1913, Frondipedia Martins & Napp, 1984 , and three species of Oxycoleus Lacordaire, 1869 : O. gahani (Gounelle, 1911) , O. laetus Julio, 1997 , and O. tristis (Melzer, 1933) .

Oxylopsebus shares some characters with Obriini : eyes large, superior lobes well separated; antennomere V longer than III and IV; procoxal cavities closed behind, and legs pedunculate-clavate. However the differences between Oxylopsebus and Obriini are marked. In Obriini the head is short necked, ommatidia coarse, elytra cover abdomen, pronotum narrow at base and lacks calli on disc, femora relatively short, tibia straight, and first metatarsomere longer than II+ III, three not deeply bilobed.

Luscosmodicini is monotypic, its species, Luscosmodicum beaveri Martins, 1970 (thought to live under bark and adapted to its habits) shows marked differences from Oxylopsebus : the body strongly flattened; head projects, but neck not markedly elongate; eyes large but lack superior lobes; antennomere III reduced in size, distinctly shorter than IV and scape; prosternal process reaches well beyond procoxal cavities but relatively wide (not laminiform at base); mesosternal process robust, as wide as coxae and truncate at apex; elytra cover abdomen; front and middle legs short; all femora more or less fusiform with very short peduncles and weak claves; only metatibia curved.

At first glance Oxylopsebus might seem to belong to the Psebiini (reduced elytra, relatively simple antennae, and pedunculate-clavate femora) but on close inspection the differences are marked. Psebiini are short-necked, eyes lack superior lobes, elytra short but truncate, or very short with broad rounded apices (not strongly dehiscent and acuminate as in Oxylopsebus ); prothorax different in form and disc of pronotum lacks calli; prosternal process laminiform but apex not spatulate, nor does it reach beyond coxal cavities; procoxal cavities open behind; mesosternal process acuminate (not subparallel with broad excavate apex as in Oxylopsebus ); and male abdomen shows only five urosternites.

Although the shortened strongly acuminate elytra of Oxylopsebus would seem to discount its inclusion in the Oxycoleini , on close inspection Oxylopsebus shares many primary characters with the Oxycoleini : the head long necked, the structure of the eyes very similar, with well developed superior lobes and fine ommatidia; prothorax narrowing from base to apex and with lateral calli; pronotum with calli on disc; procoxal cavities closed behind and angled at sides, and procoxae very prominent; mesocoxal cavities open; legs long and slender, femora clavate with elongate peduncules; and male abdomen with six visible urosternites. Most of these characters were cited by Martins (2003) as reason for separating the genus Oxycoleus Lacordaire, 1869 from the Molorchini and placing it in its own tribe. And, apart from the elytra, the differences between Oxylopsebus and Oxycoleus are less obvious: in Oxylopsebus the scape is strongly curved (a character shared with Oxycoleus tristis ); prosternal process laminiform at base, spatulate at apex and reaching well beyond coxal cavities (not flattened and acuminate, and failing to reach beyond coxal cavities); mesosternal process half as wide as coxae and excavate at apex (not almost as wide as coxae and truncate at apex); legs are very similar in both genera, longer in Oxycoleus , but in Oxylopsebus the hind legs are considerably larger than the others and all the tibiae curved, not just the metatibiae as in Oxycoleus . Finally, the elytra of the Oxycoleini not only almost cover the abdomen, but also opaque, and closely and coarsely punctured throughout (shortened, semi-translucent, and sparsely punctured in Oxylopsebus ).

In conclusion, the monotypic genus, Oxylopsebus , should be considered a member of the Oxycoleini because it shares many primary characters with other members of this tribe, few primary characters differing from this tribe and, as has been demonstrated, relatively few affinities with the other tribes of the “ Obriini group”.