Taxonomic changes in palaeotropical Xyleborini (Coleoptera, Curculionidae, Scolytinae)

Abstract Following the recent reclassification of the Palaeotropic xyleborine genera (Hulcr and Cognato in press), additional species are transferred to correct genera or synonymized based on analysis of their morphological characters. The following species are given new combinations: Debus amphicranoides (Hagedorn), comb. n., Debus birmanus (Eggers, 1930), comb. n., Debus dolosus (Blandford, 1896), comb. n., Debus eximius (Schedl, 1970), comb. n., Debus interponens (Schedl, 1954), comb. n., Debus robustipennis (Schedl, 1954), comb. n., Debus spinatus (Eggers, 1923), comb. n., Microperus alpha (Beeson, 1929), comb. n., Microperus corporaali (Eggers), comb. n., Microperus eucalyptica (Schedl, 1938), comb. n., Microperus nugax (Schedl, 1939), comb. n., Pseudowebbia percorthylus (Schedl, 1935), comb. n., Truncaudum circumcinctus (Schedl, 1941), comb. n. The following species are synonymized: Arixyleborus hirtipennis (Eggers), syn. n., with Arixyleborus puberulus (Blandford); Coptoborus palmeri (Hopkins), syn. n., with Debus emarginatus (Eichhoff); Coptoborus terminaliae (Hopkins), syn. n., with Debus emarginatus (Eichhoff); Cyclorhipidion polyodon (Eggers), syn. n., with Truncaudum agnatum (Eggers); Euwallacea artelaevis (Schedl), syn. n., with Planiculus bicolor (Blandford); Xyleborinus perminutissimus (Schedl), syn. n., with Xyleborinus perpusillus (Eggers); Xyleborus exesus Blandford, syn. n., with Debus emarginatus (Eichhoff); Xyleborus fulvulus (Schedl), syn. n., with Microperus corporaali (Eggers); Xyleborus marginicollis (Schedl), syn. n., with Diuncus justus (Schedl); Xyleborus shoreae Stebbing, syn. n., with Debus fallax (Eichhoff). The following species are given new status: Streptocranus superbus (Schedl, 1951), restored name; Webbia divisus Browne, 1972, restored name; Webbia penicillatus (Hagedorn, 1910), restored name. Genus Taphrodasus Wood (1980) is declared not valid.


Introduction
Xyleborini are one the most species-rich groups of scolytine beetles, and one which produced many invasive pests. In spite of the economic concern, xyleborine beetles have received comparatively little attention by taxonomists. S. L. Wood (1989) made the fi rst major attempt to organize the many hundreds of described species into a generic classifi cation. Th is classifi cation was subsequently adopted in the most comprehensive treatise on scolytine taxonomy, the Catalog of Scolytidae and Platypodidae (Wood and Bright 1992, Bright and Skidmore 1996, 2002, also on-line at: http:// www.scolytid.msu.edu). Th is concept was later refi ned using morphological cladistics (Hulcr et al. 2007a, Hulcr andCognato, 2009), and currently summarized by Alonzo-Zarazaga and Lyal (2009). Hulcr and Cognato (in press) provided further rearrangements of Palaearctic and Palaeotropical Xyleborini classifi cation using a combination of morphological and molecular approaches. Th is work augments the latest classifi cation with a series of transfers and synonyms. Majority of the species treated here occur in SE Asia or Melanesia.
Comments. Lectotype of Arixyleborus hirtipennis bears all essential features of A. puberulus, only the declivital rugosities more organized into rows, shining area of elytra smaller, less clearly distinguished from rugose area. Th ese are exceptionally plastic in A. puberulus, A. hirtipennis represents small deviation in the large range of variation of declivital surface in A. puberulus.
Comments. Type specimen of X. marginicollis Schedl represents one end of a continuum of variation in D.justus: short (1.5 mm) but robust (most representatives of D. justus slightly longer and more slender). Diagnostic characters identical: surface of declivity devoid of vestiture, no elytral denticles, smooth impression across interstriae 2 and 3 (very shallow).
Comments. Prolonged large representative of Debus. Elytral declivity deeply excavated, edge of declivity with two pairs of long teeth, but only few tubercles. Declivital surface smooth.

Xyleborus dolosus
Diagnosis. Elytral declivity slightly with much higher number of declivital tubercles than other Debus. Declivity fl at, not excavated, not emarginate at apex. Depth of emargination varies. Similar to Debus pumilus, but uniformly brown, with more and larger tubercles on the declivity. Signifi cant intraspecifi c size variation.
Comments. Elytral declivity superfi cially diff erent from other Debus spp, but its structure homologous. Few small or large tubercles in the interstriae 1 (usually 3 pairs), displaced by broadened interstriae 1 and positioned on fi rst striae or on interstriae 2. Strial punctures greatly reduced on declivity, diffi cult to follow as interstria 1 broad, displacing other striae. No tubercles originating on second striae. Smaller tubercles on striae 3 and beyond, creating tuberculated area surrounding declivity. Other characters shared with Debus spp.: extended pronotal disc, triangular protibiae with large and long but sparse denticles (<7), infl ated prosternal posterocoxal process, antennal club shape.
Comments. Elytral apex not emarginate, but all other diagnostic characters of Debus present: elongated pronotal disc, broad antennal club type 2, triangular protibiae, fl at elytral declivity with tubercles on elevated lateral sulcus (appears as if formed by interstriae 2 through 4).

Xyleborus interponens
Comments. All diagnostic features of genus Debus present, including antennal club form, prolonged pronotum, emarginate declivity. Similar to D. amphicranoides (Hagedorn), but with less constricted declivity and longer posterolateral declivital processes. Schedl (1954) considered D. interponens altitudinal variant of D. robustipennins, the two are allegedly identical, only diff ering by their origins from diff erent elevations.
Comments. All diagnostic features of Debus present, including antennal club form, prolonged pronotum, emarginate declivity.
Lectotype of X. robustipennis Schedl very similar to non-type specimens of Debus amphicranoides (Hagedorn) in USNM, only slightly larger. Schedl (1954) indicated that X. robustipennis diff ers from X. amphicranoides very little, merely by shallower and wider declivital emargination, having the lateral declivital costa between teeth 1 and 2 more elevated, and lateral declivital process shorter. Type of D. amphicranoides not available, thus synonymy could not be confi rmed.
Diagnosis. An "elegant" form of D. fallax. Longer, smooth declivity, shallowly emarginate, no tubercles or granules on declivital sides except two pairs of slender teeth, one long, one short. Declivity shagreen when dry.

Xyleborus alpha
Comments. All diagnostic features of Microperus present: small size, elytral punctures aligned in striae, and prolonged body shape (Hulcr and Cognato in press). Similar to Microperus pometianus, but slightly longer, with distinctly elevated and long declivital costa.
Comments. All diagnostic features of Microperus present (elytral mycangia, absence of scutellum, small size, prolonged body shape, abundant vestiture). Similar to M. intermedius, but substantially longer, elytra often bicolored, usually without convexity on elytral disc.
Diagnosis. Very similar to Microperus diversicolor (e.g., antennal club type 3), except pronotum bright yellow with brown patch, elytra black, declivity commencing closer to elytral base, declivital interstriae covered with many small sharp hooks (similar as in M. parva, but larger). Characteristic elytral disc: anterior portion infl ated, convex, boundary between elytral disc and declivity slightly concave, impressed.
Comments. Holotype of X. artelaevis virtually identical to Planiculus bicolor (Blandford), except fi rst segment of antennal club more convex. All other characters identical, including uniform granules in declivital interstriae 1, 2, and 3 (same size granules in interstriae 1-3 characteristic for P. bicolor). X. artelaevis holotype deteriorated, missing or damaged body parts including antenne.
Comments. Diagnostic characters of Pseudowebbia: regular type of pronotum (not extremely prolonged and fl at as in Webbia), circular antennal club (not broadened), triangular to broadly rounded protibia (not thin and sickle-like as in Webbia). Elytral declivity deeply excavated, surrounded by highly elevated circumdeclivital costa with no teeth.
Type species of Taphrodasus Wood, 1980. Morphological limits of Taphrodasus never specifi ed. Characters listed by Wood (1980) are either autapomorphic to T. percorthylus, or present in other genera, mostly Webbia. Taphrodasus not a valid genus, see below.
Comments. Transferred to Taphrodasus (Wood and Bright, 1992) without discussion of characters. Webbia synapomorphies: dorsal aspect of pronotum long and quadrangular, pronotal disc long and fl at, frontal slope of pronotum short, scutellum suppressed, costate and setose elytral bases. Diff ers from most Webbia spp. by densely pubescent and excavated declivity and elongated body shape. Length: 2.4 mm. Characters shared with Pseudowebbia percorthylus [(Schedl, 1935): Hulcr and Cognato, this volume] (type species of Taphrodasus) limited to excavated declivity with dense setae, genus-level characters diff erent.