A review of the powderpost beetle genera Xylothrips Lesne, 1901 and Calophagus Lesne, 1902 (Coleoptera: Bostrichidae: Bostrichinae: Xyloperthini)

This paper reviews the genera Xylothrips Lesne, 1901 and Calophagus Lesne, 1902, and their species, and proposes that Calophagus should be reinstated as a full genus from a subgenus of Xylothrips (contra Borowski & Węgrzynowicz 2019). The genera and their included species are diagnosed and redescribed, and a summary of information on the distribution and biology of all species is provided. The importance of characters of the antennal club and pronotum in separating the two genera is stressed. A key to the two genera and the two species of Xylothrips is provided.


Material and methods
In the course of this study, the author has examined all available types, other specimens of Xylothrips and Calophagus in numerous European museums and certain private collections, and the online database of insect types of the Museum of Comparative Zoology, Harvard University. Photographs were taken with a Panasonic Lumix GX8 digital camera, combined using the program CombineZP, and optimized with Adobe Photoshop CS2. labrum transverse with a fringe of long hairs along anterior margin. Mandibles subequal, sharply pointed. Eyes rather large, oval, detached from temples posteriorly. Antenna with 10 antennomeres, fi rst two elongate, antennomeres 3-7 forming a funicle, each antennomere transverse, the fi fth widest, together about as long as fi rst antennomere of club, antennomeres 8-10 forming elongate club, about twice as long as rest of antenna; lacking distinct, clearly defi ned sensory impressions or stiff hair area on all antennomeres; fi rst two antennomeres of antennal club about 1.2 -1.5 times as long as wide and last antennomere slender, about 2-3 times as long as wide, elongate oval.
PRONOTUM. Slightly wider than long, anterior angles with a rather long, upcurved uncinate tooth; sides moderately to broadly rounded, attenuated anteriorly, widest close to posterior margin of pronotum; anterior margin between unci concave, rugose; area above anterior margin fl at or weakly impressed, and strongly, densely punctured; with a series of upwardly-directed teeth laterally, gradually reduced in size from anterior to posterior, mixed with small teeth and tubercles to summit of pronotum, with fi ne, shallow, well-separated punctures; sides with distinct ridge-like lateral carinae which extend along posterior margin and form sharply tipped posterolateral angles; ventro-lateral punctures with sparse, long, white pubescence.
ELYTRA. Subequal to pronotum in width, strongly convex, shining, and strongly, evenly punctured, almost glabrous on disc and declivity, only sparse and very tiny pubescence on apical part of declivity, sutural margin slightly raised from summit to near apex of declivity and rather strongly raised at apex of declivity. Upper margin of declivity with three pairs of tubercles and one pair of elongate calluses at side.
ABDOMEN. Ventral side covered by short, white pubescence, last ventrite with narrow pleural pieces along margin and a tuft of long hairs in middle in both sexes.
LEGS. Subequal in length, procoxae contiguous, mesocoxae narrowly separated, pro-and mesotibiae grooved on external face, widened to apex. Posterior tibiae with a few long bristles on outer side, very dense, short, golden hairs rimming ventroposterior margins of posterior femora. Second and third segments of tarsi usually distinctly wider than following segments.

Sexual dimorphism
The genus shows clear sexual dimorphism in the vestiture of the frons. In the female, the frons is more densely and fi nely punctured, and the upwardly directed hairs are much longer and denser than in the male. The frontal hairs are yellowish, forming a crown with rather short, erect hairs inside. In the male, the frontal hairs are short with only a small tuft of very long hairs next to the eyes.

Biology
As a member of the dry wood borer family Bostrichidae, Xylothrips usually occurs in forest habitats (pers. obs.). From the records of host plants, the genus, like almost all other bostrichids, is certainly polyphagous and attacks orchard trees as well as forest trees (Lesne 1901(Lesne , 1932Stebbing 1914;Beeson & Bhatia 1937). In tropical areas, there is more than one generation per year (Beeson & Bhatia 1937), and high populations can cause economic problems in orchards and other forest plantations.

Distribution
India, Nepal, Southeast Asia, Australia, the archipelagos of the Indian Ocean and Pacifi c Ocean, Madagascar.

Diagnosis
This species is easily separable from X. religiosus by the reddish brown body, the shallower frontoclypeal suture, the absence of punctures on the lateral part of the pronotum, the extension of the inferolateral callus, which converges into the lower lateral margin of the elytra (Fig. 2B), and the apical sutural angles raised with tubercles beneath the margin.

Material examined
The author has examined the type of Apate fl avipes from 'Afrika' in MNB, and the type of Bostrichus mutilatus from Sri Lanka (Ceylon) in NHMUK. The author has also examined more than 1000 specimens identifi ed by Lesne, Vrydagh and others in 13 museums (RBINS, MIZPN, MNB, MTM, NHMUK, NMBS, NME, NMPC, NMS, NMW, SDEI, SNSD and ZSM) as well as in private collections (LYL, MAIC and PZP), mainly from Southeast Asia and the archipelagos of the Indian Ocean and Madagascar, but detailed locality data were not recorded.

New records
The author received 10 specimens collected from Xishuangbanna, Yunnan, China. This is the fi rst record of the species from China. The data for the specimens are as follows: In addition, two more specimens were collected from the branches of a rubber tree (Hevea brasiliensis Müll.Arg.) in Jinghong, Xishuangbanna during Jan. 2018 (S.C. Lai, pers. comm.).
HEAD. Clypeus fi nely and densely punctured, concave in an arc in front. Fronto-clypeal suture distinguished by different colour between frons and clypeus or shallow suture with vertical longitudinal furrow in middle ending on anterior margin of clypeus. Frons with punctures less fi ne and less dense than on clypeus, slightly rough, covered by fairly long, fi ne pubescence directed upwards. First antennomere elongated, second antennomere sub-rectangular, each funicle segment with a rim of long hairs in middle, total length of funicle as long as or shorter than fi rst antennomere of antennal club, fi rst and second antennomeres of antennal club 1.3-1.5 times as long as wide, last antennomere rather elongated, about 2.5-3 times as long as wide. Club matt, without clear sensory impressions or an area with stiff hairs (Fig. 1C).
PRONOTUM. About 1.2-1.3 times as wide as long, fairly strongly narrowed in anterior third, widest in basal part; a distinct upwardly-directed uncinate tooth on anterolateral angle and a series of upwardlydirected teeth behind form lateral border of rasp on anterior half of pronotum, teeth gradually smaller and less erect towards summit of pronotum and posterior border of rasp formed by small tubercles or granules, bearing yellowish-red, short, recumbent pubescence between teeth ( Fig. 2A, D); area above anterior margin between uncinate teeth fi nely and more or less roughly punctured; median and posterior areas shiny with fi ne, sparse punctures; sides evenly rounded behind rasp; distinct, ridge-like lateral carinae extended to basal margin of pronotum to form pointed posterolateral angles (Fig. 1D). Basal half of pronotum with minute, moderately dense punctures in middle only; laterally shining, glabrous, tiny white hairs present close to infero-lateral margin (Fig. 1C).
ELYTRA. 1.7-1.85 times as long as pronotum, 1.45-1.65 times as long as wide, disc parallel-sided, widest at middle of declivity. Elytra shining, with sparse, moderately fi ne and shallow punctures on disc, becoming deeper and larger on posterior part of disc and declivity, upper half of declivity with strongest punctures. Upper margin of elytral declivity with three pairs of tubercles, middle one largest, with pointed tip and projecting furthest, other two forming short ridges with rounded tips, infero-lateral callus extended and joining directly to infero-lateral margin of elytra ( Fig. 2B-C). Elytral suture raised from upper margin of declivity and gradually swollen and thickest at apex, where it forms rounded thickened angles, margin of elytra with one or several tubercles on ventral side near sutural angle, which projects slightly. ABDOMEN. Ventral side vestiture with dense, white or reddish yellow pubescence, last ventrite with narrow pleural pieces along margin to apical curved area, with a long tuft of hairs in middle.
LEGS. Dense, short golden hairs on ventroposterior margins of posterior femora (Fig. 2E). External face of pro-and mesotibiae broadly grooved, not narrowed towards apex. Segments 2 and 3 of anterior tarsi distinctly wider than others.

Male
HEAD. Frons transversely convex, densely and very fi nely punctured, very fi nely pubescent, with a few erect hairs next to inner margin of eyes. Clypeus with a transverse band of upwardly directed hairs towards base with a narrow median line (Fig. 1C).

Female
HEAD. Frontal crown of hairs very thick, forming arc of a circle or a very wide V, fairly distant laterally from eyes. Clypeal tufts of hairs as long as those on frons ( Fig. 2A, D-E).

Biology
Stebbing (1914)  It is apparent that X. fl avipes is a polyphagous species. It has usually been collected from forests or orchards, not lumber yards, timber processing premises or wooden items. Beeson & Bhatia (1937) found that X. fl avipes has two generations a year in North India and recorded the fi rst generation emerging from the end of March to the end of May, with maximum abundance in the third week of April, a second generation from the fi rst week of July to the third week of October. From logs of Mangifera indica (Anacardiaceae) felled in August, X. fl avipes was found to have a minimum life-cycle of three months (Beeson & Bhatia 1937). Sittichaya et al. (2013) surveyed the durian-based orchards in Southern Thailand and found X. fl avipes was the dominant species in the durian growing areas.

Distribution
The distribution includes: Madagascar, I ndian Ocean islands, Sri Lanka, India, Nepal, China (Yunnan), Southeast Asia, Philippines, Indonesia. It has probably been introduced through human agency into the Mariana Is., Palau and the Federated States of Micronesia in the Western Pacifi c. It has also been introduced into the Arabian Peninsula, Socotra Island (Yemen), South Africa (Natal), Israel, Europe and USA (Borowski & Węgrzynowicz 2007, 2019. Roberts (1968) recorded the species in Sapele, Nigeria at light. There are more than 10 specimens deposited in MNB and 7 specimens in SDEI from Ethiopia. This suggests that the species is established in that country. In the RBINS collection, there is one specimen (Vrydagh ident.) collected from NSW, Australia in 1914 from imported wood from India, and one specimen from Melbourne, Australia in SDEI. These appear to be accidental introductions. (Boisduval,  Apate religiosae -Fairmaire 1850: 50 (in part).

Diagnosis
The species is distinguished from X. fl avipes by the slightly smaller size and darker body, and the often entirely dark brown, fronto-clypeal suture with a median fovea. The middle of the lateral and posterior parts of the pronotum behind the asperities of recumbent teeth with extremely fi ne, moderate to sparse punctures. Punctures stronger on the disc of the elytra, three pairs of tubercles on the upper margin of the declivity not as developed as in X. fl avipes, the lateral callus not converging into the lateral margin of the declivity. Elytral suture slightly raised, not as swollen as in X. fl avipes, the apical angles raised a little without tubercles beneath the margin.

Material examined
Borowski & Węgrzynowicz (2007) suggested that the type material of Apate religiosa could be in NHMUK and the Montrouzier types should be deposited in MNHN, but after the author examined 427 specimens of X. religiosus in NHMUK (plus one under X. geoffroyi), she did not fi nd any one bearing a 'type' label. Similarly, no type specimens of Xylothrips were found in MNHN. Hence, the type material was not located, but the species is well-known in the archipelagos of the South Pacifi c Ocean, and in Australia.
The author has examined numerous specimens identifi ed by Lesne and Vrydagh, and more than 1170 specimens were checked at several museums (RBINS, MIZPN, MNB, MTM, NHMUK, NMBS, NME, NMPC, NMS, NMW, SDEI, SNSD and ZSM) and in private collections (LYL, MAIC and PZP), but detailed locality data were not recorded. The specimens were mainly from Papua New Guinea, New Caledonia and the archipelagos of the South Pacifi c Ocean.
HEAD. Clypeus fi nely and densely punctured, almost glabrous in middle, concave in a wide arc in front with a tuft of erect, long and yellowish-red hairs on both sides of clypeus. Fronto-clypeal suture distinct, with median fovea. Frons with puncturation denser than on clypeus, slightly rough, covered by fairly long, fi ne pubescence directed upwards. First antennomere longer than wide, second antennomere shorter, each funicle segment with a rim of long hair on middle, total length of funicle as long as or shorter than fi rst antennomere of antennal club, fi rst two antennomeres of antennal club about 1.5 times as long as wide, last antennomere rather elongated, about 3 times as long as wide. Club matt, without clear sensory impression areas or erect hairs (Fig. 1E).
PRONOTUM. 1.25-1.35 times as wide as long, fairly strongly narrowed in anterior third, widest in basal part; a distinct upwardly-directed uncinate tooth on anterolateral angle and a series of upward-directed teeth behind form lateral border of rasp on anterior half of pronotum, teeth gradually smaller and less erect towards summit of pronotum, posterior border of rasp formed by small tubercles or granules, bearing dense, white, short, recumbent pubescence between and on teeth (Figs 1E, 3A); area above anterior margin between uncinate teeth densely, fi nely and more or less roughly punctured; median and posterior areas of pronotum shiny with fi ne, sparse punctures, posterolateral areas with denser punctures and short, white-yellowish hairs; sides evenly rounded behind rasp; a distinct ridge-like lateral carina extends to basal margin of pronotum to form tip of posterolateral angles (Fig. 1F).
ELYTRA. 1.8-1.95 times as long as pronotum, 1.4-1.55 times as long as wide, parallel-sided at disc and widest at middle of declivity. Elytra shining, with sparse, fi ne and shallow punctures on disc, becoming deeper and larger towards lateral and posterior parts, upper half of declivity with strongest punctures. Entirely glabrous, with tiny white hairs along lateral and apical margins. Upper margin of elytral declivity with three pairs of tubercles, middle one largest and most strongly projecting, with pointed tip, other two forming short ridges with round ends, infero-lateral callus not extending to lower lateral margin of elytra ( Fig. 3C-D). Elytral suture raised from middle of disc, gradually more swollen and thickest at upper margin of declivity, apex of declivity slightly projected.
ABDOMEN. Ventral side vestiture with dense, white or reddish yellow pubescence, last ventrite with narrow pleural pieces along margin.
LEGS. Dense, short golden hairs on ventroposterior margins of posterior femora. External face of pro-and mesotibiae narrowly grooved, not narrowed towards apex. Segments 2 and 3 of anterior tarsi distinctly wider than others. Male HEAD. Frons transversely convex, densely and very fi nely punctured, a small shining callus in middle (Fig. 3A); yellow, erect pubescence covers areas from callus to eyes and fronto-clypeal suture, short and recumbent toward middle and gradually longer towards eyes, with a tuft of long, erect hairs next to inner margin of eyes. Clypeus with a transverse band of upwardly directed hairs towards base with a narrow median line and a tuft of long, erect hairs on both sides of clypeus (Fig. 1E).

Female
HEAD. Frontal crown of hairs very thick, forming arc of a circle or a very wide V, fairly distant laterally from eyes. Clypeal tufts of hairs as long as those on frons.

Remarks
Montrouzier (1861)  Borowski & Węgrzynowicz (2019) synonymised Apate geoffroyi with X. religiosus without examination of the type material, but inferred that Montrouzier misinterpreted the differences between the sexes. Lesne (1901) mentioned that specimens with reduced marginal tubercles of the elytral declivity are found in New Caledonia, and that one specimen from the Cape York peninsula, Australia was notable for the much stronger elytral punctures than found in other specimens, the very fi ne, but very distinct, punctures in the middle of the pronotal disc, and the weaker projection of the lowermost marginal tubercle of the elytral declivity. Variations in the punctures on the posterior half of the pronotum and in the development of the marginal tubercles of the elytral declivity were often found during the present study.

Biology
In Tahiti, X. religiosus has been recorded from the breadfruit tree (Moraceae: Artocarpus altilis (Parkinson) Forsberg), and in the 'bourao' (Malvaceae: Hibiscus tiliaceus L.). In Melanesia, the species attacks many trees, even the hardest ones, but its multiplication is reduced by a clerid beetle of the genus Cylidrus. The adults fl y in the evening and are attracted to light (Lesne 1901).

Distribution
Indonesia, Papua New Guinea, Australia, New Caledonia and the archipelagos of the South Pacifi c Ocean. This species has been introduced to USA, Africa and Europe (Borowski & Węgrzynowicz 2019).
This genus was erected by Lesne (1902) for the single Chinese species, Calophagus pekinensis. Reichardt (1966) described a new Chinese species, Xylothrips cathaicus, from the same area as C. pekinensis. Park et al. (2015) synonymised X. cathaicus with C. pekinensis as Xylothrips pekinensis based on the black and white fi gures of a new record of X. cathaicus from Tsushima Island, Japan (Iwata & Kusakabe 2002) and a new record of C. pekinensis from the same location (Borowski & Węgrzynowicz 2008), but without examining the type material of either species (S. Park, pers. comm.). Borowski & Węgrzynowicz (2019) accepted the synonymy given by Park et al. (2015) and downgraded Calophagus to a subgenus of Xylothrips. They treated Xylothrips (Calophagus) pekinensis as a new combination. Lesne (1902) deposited 5 syntypes of Calophagus pekinensis in MNHN, and Reichardt (1966) deposited the holotype and 3 paratypes of Xylothrips cathaicus in MCZ, and one paratype in the Department of Zoology, Saõ Paulo, Brazil. The author has examined the 5 syntypes of C. pekinensis in the R. Oberthür collection (MNHN), and the photos of the holotype of X. cathaicus from the Insect Type Database website of MCZ. Both agree with Lesne's description of C. pekinensis. The synonymy of X. cathaicus with C. pekinensis is confi rmed. The reasons for the retention of Calophagus as a distinct genus are discussed below.
The distribution of the genus is confi ned to North China, South Korea and Tsushima Island in Japan.

Diagnosis
As a member of Xyloperthini Lesne, 1921, the genus closely resembles the preceding genus. It differs from Xylothrips in the following characters: rather dull, not as shining as the preceding genus; antennal club without clearly impressed sensory areas, but each of its three antennomeres with two longitudinal bands of golden hairs on each side of each face; pronotum without lateral carina, a few granules on the posterolateral angles form the tip of the angles; very fi ne punctures all over the elytra, the declivity abruptly declivous with three pairs of small tubercles on the upper margin, the middle one slightly larger, lateral callus small and close to lateral margin of the declivity. Lesne, 1902 Figs 1A-B, 4 Calophagus pekinensis Lesne, 1902: 109. Xylothrips cathaicus Reichardt, 1966. The specifi c identity of more than 20 specimens was checked in several museums (RBINS, MNHN, NMBS, NMPC (as Xylothrips cathaicus) and SNSD) and private collections (LYL, MAIC and PZP (as X. cathaicus)), but detailed locality data were not recorded.

Description
BODY. Stout, cylindrical, 6-8.5 mm long. Head deeply inserted in prothorax, not visible from above. Antennae, pronotum, elytral disc and profemur brown-red, other parts of body dark brown to black on ventral side. HEAD. Eyes rather large, oval, detached from temples posteriorly. Clypeus fi nely and densely punctured, anterior margin forming two arcs with a tooth in middle, anteriorly with a tuft of erect hairs, a band of long, yellowish-red hairs on transverse middle line. Fronto-clypeal suture distinct, with a vertical furrow. Frons with punctures denser than on clypeus, slightly rough, covered by fairly long, fi ne pubescence directed upwards, a small shining callus in middle (Fig. 4A). First antennomere longer than wide, second antennomere shorter, total length of funicle shorter than fi rst segment of club; fi rst antennomere of antennal club subtriangular, second antennomere of antennal club rectangular, about 1.2 times as long as wide, last antennomere rather elongated, about 2.5 times as long as wide. Each antennomere of antennal club with longitudinal bands of golden hairs on each side of each face (Figs 1A, 4A). Labrum yellowish, with dense punctures, fringed with long hairs on anterior margin. Both mandibles pointed at tip.
PRONOTUM. Slightly wider than long, fairly strongly narrowed in anterior third, widest in basal part; a distinct upwardly-directed uncinate tooth on anterolateral angle and a series of upwardly-directed teeth behind form lateral border of rasp on anterior half of pronotum, teeth gradually smaller and less erect towards summit of pronotum; posterior margin of rasp formed by small tubercles or granules, bearing sparse, yellowish-red, short, recumbent pubescence between and on teeth (Fig. 4A); area above anterior margin between uncinate teeth fi nely and more or less roughly punctured; posterior half of pronotum very smooth, impunctate; sides evenly rounded behind rasp; lateral carina absent, posterolateral angles rectangular, with a few small granules on tip (Figs 1B, 4B); anterolateral part of pronotum with sparse punctures with dense, long, white, recumbent pubescence (Figs 1B, 4A). ELYTRA. Punctures of elytra fairly fi ne, superfi cial, obsolete anteriorly and near margins of apical declivity; declivity shining and very smooth, very obscurely punctured, margined on each side by three subequal blunt tubercles and by an infero-apical callus in form of a fold, separated from elytral margin by marginal groove (Fig. 4C-D). Suture slightly projecting on declivity, weakly refl exed at apex.
ABDOMEN. Covered with grey, appressed pubescence, very dense and quite long, last ventrite with pleural pieces along lateral margins.
LEGS. Dense, short golden hairs on ventroposterior margins of metafemora. Anterior face of anterior tibiae uniformly pubescent, external face of posterior tibiae with numerous, long golden hairs. Segments 2 and 3 of anterior tarsi distinctly wider than others.

Male
HEAD. Frons transversely convex, densely and very fi nely punctured, a small shining callus in middle (Fig. 4A), yellow erect pubescence covers areas from callus to eyes and fronto-clypeal suture, short and recumbent toward middle and gradually longer closer to eyes, with a tuft of long, erect hairs next to inner margin of eyes. Clypeus with a transverse band of upwardly directed hairs towards base, with a narrow median line (Fig. 4A).
ABDOMEN. Last ventrite with pleural pieces, foveolate in middle behind apical margin.

Female
HEAD. Frontal crown of hairs very thick, forming arc of a circle or a very wide V, fairly distant laterally from eyes. Clypeus with a transverse band of upwardly directed, long hairs towards base, with a narrow median line.
ABDOMEN. Last ventrite with pleural pieces, impression in middle behind apical margin shallower than in male.

Remarks
The specimens from South Korea are more shining, particularly on the apical half of the elytra, which may be almost as shining as in Xylothrips fl avipes. The specimens from China and Tsushima Island are rather matt. The lateral callus on the elytral declivity is more reduced in the male than in the female, and is almost lost in the male from Tsushima Island, with only a short carina remaining. Iwata & Kusakabe (2002) recorded 8 males and 13 females of Xylothrips cathaicus from dead branches of Zelkova serrata (Thunb.) Makino (Ulmaceae) in April, 1990, on Tsushima Island, Japan. Chen (1990) recorded 4 males and 6 females of Xylothrips cathaicus collected from Styphnolobium japonicum (L.) Schott (Leguminosae) in April, 1987, in Beijing. Zhan (1984 studied the "common pest", Calophagus pekinensis, of timber and the wood used in the construction of houses in Hubei, China, and found that the species has one generation per year. The developmental periods of the immature stages were: eggs 8-10 days; larvae about 110 days; pupa about 12 days. Adults lived for about 230 days in Hubei, China and bred in Pterocarya stenoptera C.DC. (Juglandaceae). The clerid beetles Tarsostenus univittatus (Rossi, 1792) and Tillus notatus Klug, 1842 prey on larvae and pupae (Zhan 1984). Doryctinae Forster, 1862 (Hymenoptera: Braconidae Latreille, 1829) and Bethylidae Forster, 1856 (Hymenoptera) were observed to be parasitic on larvae and pupae during the study (Zhan 1984). In 2008, the author received a series of specimens from Shandong, China collected from Rosa rugosa Thunb. (Rosaceae) in Aug. 2007. S. Park collected specimens of this species from the freshly cut wood of an apple tree (Rosaceae: Malus domestica Borkh.) in an orchard, together with Xylosandrus spp. (Scolytinae). It is also known to attack Chionanthus retusus Lindl.&Paxton (Oleaceae) (S. Park, pers. comm.).