Research Article |
Corresponding author: Wisut Sittichaya ( wisut.s@psu.ac.th ) Academic editor: Miguel Alonso-Zarazaga
© 2021 Wisut Sittichaya, Sarah M. Smith, Roger A. Beaver, Narit Thaochan.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Sittichaya W, Smith S, Beaver RA, Thaochan N (2021) Revision of the xyleborine ambrosia beetle genus Microperus Wood, 1980 (Curculionidae, Scolytinae, Xyleborini) of Thailand with four new species and four newly recorded species. ZooKeys 1074: 191-214. https://doi.org/10.3897/zookeys.1074.76235
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Microperus Wood, 1980 ambrosia beetles in Thailand are reviewed. Four species, M. bidentatus sp. nov., M. bucolicus sp. nov., M. globodeclivis sp. nov., and M. serratus sp. nov. are described. Four new combinations are given: Microperus armaticeps (Schedl, 1942) comb. nov., Microperus exsculptus (Eggers, 1927) comb. nov., Microperus pedellus (Schedl, 1969) comb. nov., and Microperus spicatulus (Browne, 1986) comb. nov., stat. res., all from Xyleborus. Two new synonyms are proposed: Microperus cruralis (Schedl, 1975) (= Xyleborus myllus Browne, 1986 syn. nov.), Microperus exsculptus (Eggers, 1927) (= Xyleborus dentipennis Browne, 1983 syn. nov.). Four species are reported from Thailand for the first time: Microperus chrysophylli (Eggers, 1930), Microperus exsculptus, Microperus nanus (Browne, 1949) and Microperus quercicola (Eggers, 1926). With the inclusion of the Microperus species described and recorded herein, the diversity of Microperus is increased to 35 species, of which 18 are recorded in Thailand. An updated key to the Microperus of the Indochinese Peninsula and China is provided. The taxonomy, diagnostic characters, and distribution of species are briefly discussed.
Key, Microperus, new combinations, new records, new species, new synonymy, Oriental region, Thailand
The xyleborine ambrosia beetle genus Microperus was first erected by
Microperus currently contains 27 species distributed in Asia from Far East Russia, Korea and Japan, west to Sri Lanka and southeast to Papua New Guinea and Australia. Eighteen species are distributed in Indochina and China, and Thailand has the greatest diversity (
Specimens were collected from 27 study sites in 24 conservation areas across all regions of Thailand. Southern Thailand was sampled between 2014–2015 and the North, Northeast and East were sampled between 2019–2020 (Fig.
Photographs were taken with a Canon 6D digital Camera with a Canon MP-E 65 mm Macro Photo Lens (Canon, Tokyo, Japan) and StackShot-Macrorail (Cognisys Inc, Michigan, USA). The photos were then combined with Helicon Focus 6.8.0. (Helicon Soft, Ukraine); all photos were improved with Adobe Photoshop CS6 (Adobe Systems, California, USA). The antennal and pronotum types and characters follow those proposed by
RABC Roger A. Beaver collection, Chiang Mai, Thailand;
THNHM Natural History Museum of the National Science Museum, Thailand;
WSTC Private collection of Wisut Sittichaya, Songkhla, Thailand.
Microperus Wood, 1980: 94.
Xyleborus theae Eggers, 1940 (= Xyleborus myristicae Schedl, 1939); original designation.
This genus is distinguished by the following combination of characters: small to minute size, 1.2–3.1 mm long and cylindrical and elongate form, 1.9–3.2× as long as wide; antennal club truncate or flattened, segment 1 costate, segment 2 or segments 2 and 3 visible on anterior side small and appearing soft, segment 2 or segments 2 and 3 visible on posterior side (types 2, 3, 4 of
Coptodryas, Xyleborinus
Holotype
, female, Thailand, Trang Province, Khao Banthat Wildlife Sanctuary, 7°24'54.6"N, 99°49'47.5"E, tropical rainforest, ethanol baited trap, 01.xii.2013, W. Sittichaya, (
M. recidens.
1.68–1.76 mm (mean = 1.72 mm; n = 2) long, 2.80–2.89 (mean 2.85× as long as wide). This species is distinguished by its cylindrical appearance, elytral disc shining and convex, declivity steep, declivital interstriae 1 and 2 flat, slightly impressed, declivital interstriae 3–6 convex on basal half, with a pair of prominent tubercles on interstriae 3, apical half flattened. This species differs from M. recidens by the elytral disc more flattened, declivital summit less steep, declivital face more flattened and broader, and declivity armed with a pair of prominent tubercles on interstriae 3 (those much smaller in M. recidens).
Body greenish brown to brown. Head: epistoma entire, transverse, with a row of hair-like setae. Frons weakly convex shagreened, covered with sparse vestiture, punctate, punctures shallow with a short erect hair-like setae. Eye shallowly emarginate just above antennal insertion, upper portion slightly smaller than lower part. Submentum large, distinctly triangular, moderately impressed. Antennal scape short and thick, subequal in length with club. Pedicel slightly broader than scape, shorter than funicle. Funicle 4-segmented, segment 1 shorter than pedicel. Club longer than wide (5:4), type 3, segment 1 corneous, feebly convex on anterior face, occupying basal 1/3, covering 2/3 of posterior face; segment 2 short, soft; segment 2 present on posterior face, soft. Pronotum: 1.20× as long as wide, elongate and subquadrate, type 7 in dorsal view, lateral sides parallel to anterior 3/4, rounded anteriorly; anterior margin without serrations; base weakly concave, posterior angles rounded. In lateral view disc slightly longer than anterior slope, type 7, summit at apical 2/5, anterior slope densely asperate; disc slightly convex, subshiny, impunctate; lateral margins obliquely costate. Elytra: 1.55× as long as wide, 1.33× as long as pronotum. Scutellum minute, convex, slightly raised above elytral surface. Elytral mycangium indicated by a disperse median setal tuft along elytral base. Base sinuate, edge carinate, humeral angles rounded, parallel-sided in basal 7/8, then narrowly rounded to apex. Disc shiny, moderately convex, striae not impressed, with large shallow punctures, setose, setae very short, semi-erect, hair-like; interstriae flat, impunctate, setose, setae long erect, hair-like. Declivity abruptly commencing, declivital face on striae and interstriae 1 and 2 shallowly impressed, upper portion on 3–6 convex with a pair of prominent tubercles on interstriae 3, lower portion flattened; declivital striae 1 and 2 slightly impressed, punctate, punctures round, prominent, moderately impressed, striae 3–6 flat, punctate, punctures small; interstriae flat with a row of long erect hair-like setae. Posterolateral margin carinate to interstriae 7. Legs: procoxae contiguous; prosternal coxal piece short, inconspicuous. Protibiae slender, broadest at the middle; posterior face smooth; margin armed with six large socketed denticles. Meso- and metatibiae rounded, armed with seven large socketed denticles.
L. bi = two, dentatus = toothed, the name refers to the two prominent denticles on each declivital interstriae 3. An adjective.
Southern Thailand (Trang Province, Nakhon Sri Thammarat Province).
Unknown.
Holotype
, female, Thailand: Nakhon Sri Thammarat Province, 8°21'40.8"N, 99°39'17.3"E, durian orchard, ethanol baited trap, 1.vi.2011, W. Sittichaya, (
1.6 mm (n = 1), 2.67× as long as wide. This species is distinguished by the elytral disc flat with short, steep declivity, declivital posterolateral margin costate and denticulate, declivity with sparse minor denticles, less abundant than strial punctures, and denticles uniform in size.
M. alpha.
Head, pronotum and elytra light brown, antennae and legs yellow brown. Head: epistoma entire, transverse, with a row of hair-like setae. Frons weakly convex to upper level of eyes, subshiny, punctate; punctures large, shallow, sparse, each bearing an erect hair-like seta. Eyes moderately emarginate just above antennal insertion, upper part smaller than lower part. Submentum large, distinctly triangular, slightly impressed. Antennal scape short and thick, shorter than club. Pedicel as wide as scape, shorter than funicle. Funicle 4-segmented, segment 1 shorter than pedicel. Club longer than wide, flattened, type 3; segment 1 corneous, transverse on anterior face, occupying basal 1/4 of club; segment 2 narrow, soft; segments 1 and 2 present on posterior face. Pronotum: 1.09× as long as wide. In dorsal view basic and parallel-sided (type 2), sides parallel in basal 2/3, rounded anteriorly; anterior margin without serrations. Base weakly bisinuate, posterior angles obliquely rounded. In lateral view elongate with disc much longer than anterior slope, type 8, summit low, at apical 2/5. Anterior slope with densely spaced, broad asperities, becoming lower and more strongly transverse towards summit. Disc shagreened, alutaceous, finely punctate, glabrous, some moderately long hair-like setae at margins. Lateral margins obliquely costate. Elytra: 1.53× as long as wide, 1.4× as long as pronotum. Scutellum minute, convex, slightly raised above elytral surface. Elytral mycangium indicated by a disperse median setal tuft along elytral base. Base transverse, edge oblique, humeral angles rounded, parallel-sided in basal 4/5, then narrowly rounded to apex. Disc flat, shiny, striae clearly impressed, with large deep punctures separated by 2–3 diameters of a puncture, glabrous; interstriae flat, impunctate, setose, setae short, sparse, erect hair-like. Declivity occupying 1/3 of elytral length, steeply rounded, its margins denticulate, weakly shagreened, subshiny; striae flat, punctate, each puncture bearing a seta as long as a puncture; interstriae regularly denticulate along their lengths, denticles uniformly sized, each bearing a long erect hair-like seta. Posterolateral margin costate, denticulate to interstriae 7. Legs: procoxae contiguous; prosternal coxal piece tall, pointed. Protibiae slender, broadest at the middle; posterior face smooth; margin armed with at least six large socketed denticles (broken).
L. bucolicus = rural, rustic. In reference to the agrarian habitat in which the species was collected. An adjective.
Southern Thailand (Nakhon Sri Thammarat Province).
Unknown.
Holotype
, female, Thailand: Payao Province, Doi Phu Nang National Park, 18°51'57.7"N, 100°10'51.0"E, dry deciduous dipterocarp forest, ethanol baited trap, 01.i.2019, W. Sittichaya (
1.6 mm long (n = 1), 2.66× as long as wide. This species is distinguished by its cylindrical appearance, convex elytral disc and declivity, elytral apex globose and posterolateral margin broadly rounded without a carina. This species is differentiated from the morphologically similar M. pedellus (Schedl, 1969) by the following combination of characters (M. globodeclivis given first): less elongate form, 2.66× as long as wide vs. 2.8× as long as wide), stouter pronotum 1.08× as long as wide vs. 1.17× as long as wide, elytra 1.5× as long as pronotum vs. 1.4× as long as pronotum, and elytral base sinuate vs. broadly V-shaped.
M. pedellus.
Appearing bicolored, moderately setose: head, anterior slope of pronotum and elytra dark brown, remainder of pronotum, antennae, and legs light brown. Head: epistoma entire, transverse, with a row of dense hair-like setae. Frons weakly convex to upper level of eyes, shagreened lower part densely covered with long erect hair-like setae, punctate, punctures shallow and bearing a long, erect hair-like seta. Eye shallowly emarginated just above antennal insertion, upper and lower parts subequal. Submentum medium in size, distinctly triangular, shallowly impressed. Antennal scape short and thick, as long as club. Pedicel as wide as scape, shorter than funicle. Funicle 4-segmented, segment 1 shorter than pedicel. Club circular, broader than tall; type 3; segment 1 corneous covering about half of posterior face, anterior face costate concave, narrow; segment 2 narrowly corneous on anterior face, posterior face fully visible, segment 3 soft, visible on posterior face. Pronotum: 1.08× as long as wide. In dorsal view basic type 2; lateral side parallel to anterior two thirds; anterior margin round without medial serrations. Base weakly bisinuate, posterior angles acutely rounded. In lateral view type 7, disc slightly longer than anterior slope; disc convex, summit at apical 2/5; anterior slope densely covered with asperities; disc shagreened, impunctate; pronotum sparsely covered with moderately long hair-like setae, lateral margins obliquely costate. Elytra: 1.62× as long as wide, 1.5× as long as pronotum. Scutellum minute, convex, slightly raised above elytral surface. Elytral mycangium indicated by a disperse median setal tuft along elytral base. Base shallowly sinuate, edge oblique, humeral angles rounded. Lateral margins parallel beyond basal half, apex broadly attenuated at apical 4/5, apex broadly rounded. Declivity gradually commencing, broadly convex without posterolateral carina; elytra setose, elytral disc shinning, flat near scutellum broadly convex beyond, striae punctate, parallel laterally, puncture small, round moderately deep, punctures with shorter hair-like setae, interstriae flat, impunctate bearing a row of long erect hair-like setae, setae on disc and declivity equal in length. Legs: procoxae contiguous, prosternal coxal piece short, inconspicuously covered with a tuft of long hair-like setae. Protibiae slender, broadest at the middle; posterior face smooth; margin armed with six small socketed denticles. Meso- and metatibiae inflated; outer margin evenly rounded with seven and six small socketed denticles, respectively.
L. globus = globe, round; declivis = downhill sloping (declivity). In reference to its round declivity which lacks a posterolateral carina. An adjective.
Northern Thailand (Payao Province).
Unknown.
Holotype
, female, Thailand: Songkhla Province, Ton Nga Chang Wildlife Sanctuary, 6°59'32.1"N, 100°08'57.8"E, tropical rainforest, ethanol baited trap, 01.iii.2015, (W. Sittichaya) (
M. nugax, M. sagmatus, M. undulatus (Sampson, 1919).
1.66–1.72 mm long (mean = 1.70 mm; n = 6) 2.59–2.69× as long as wide (mean 2.64× as long as wide). This species is distinguished by elytral disc convex, posterior half of elytra striae impressed with large round punctures, impression increased posteriorly, interstriae costate with strong interstrial spines posterior to declivital summit, declivity steep, shallowly impressed on the middle to interstriae 2, interstriae 3 with small but prominent tubercles.
This species is related to M. undulatus and similar species, but elytral disc is convex, lacking a transverse or saddle-like impression.
Head : epistoma entire, transverse, with a row of hair-like setae. Frons subshiny, finely punctate, lower portion flat sparsely covered with very fine hair-like setae, upper level of eyes slightly convex; sparsely setose, setae fine. Eye shallowly emarginate just above antennal insertion, upper part smaller than lower part. Submentum large, distinctly triangular, slightly impressed. Antennal scape short and thick, as long as club. Pedicel as wide as scape, shorter than funicle. Funicle 4-segmented, segment 1 shorter than pedicel. Club longer than wide, type 3, anterior face segment 1 corneous, concave, segment 2 narrowly visible, posterior face segment 1 covering basal 2/3, segment 2 visible, appearing soft. Pronotum: 1.05× as long as wide. In dorsal view subquadrate and parallel-sided, type 3, sides parallel in basal 2/3, weakly rounded anteriorly with prominent anterolateral corners; anterior margin without a row of serrations. Base weakly bisinuate, posterior angles acutely rounded, almost subquadrate. In lateral view tall, type 2, disc flat, summit at midpoint. Anterior slope with densely spaced, broad asperities, becoming lower and more strongly transverse towards summit. Disc shagreened, alutaceous, impunctate, lateral margins obliquely costate. Elytra: 1.53× as long as wide, 1.53× as long as pronotum, Scutellum minute, convex, slightly raised above elytral surface. Elytral mycangium indicated by a disperse median setal tuft along elytral base. Base shallowly sinuate, edge oblique, humeral angles rounded, parallel-sided in basal 4/5, then narrowly rounded to apex. Disc shiny, basal half convex, striae and interstriae flat, posterior half rugose with deeply impressed striae and costate interstriae bearing strong incurved spines, becoming more prominent toward declivital summit which bears the largest incurved spine. Declivity steep, declivital face dull, striae and interstriae 1 and 2 shallowly impressed, striae 1 and 2 with prominent round punctures, interstriae 3 with two small acute denticles. Striae with short erect hair-like setae and interstriae with long setae. Posterolateral margin acutely carinate to interstriae 7. Legs: procoxae contiguous; prosternal coxal piece tall, conical. Protibiae obliquely triangular, broadest at apical 1/3; posterior face smooth; apical 1/3 of outer margin with six moderate socketed denticles. Meso- and metatibiae flattened; outer margin evenly rounded with eight moderate to large socketed denticles.
L. serratus = toothed like a saw. In reference to the serrate margin of the elytral declivity. An adjective.
Thailand (Narathiwat Province, Songkhla Province), East Malaysia (Sabah).
Unknown.
Xyleborus armaticeps Schedl, 1942: 198.
Cyclorhipidion armaticeps
(Schedl, 1942):
A dorsal habitus image of the lectotype (NMHW) was examined by all authors and the species is transferred from Cyclorhipidion to Microperus because of the following characters: dense tuft of setae present along elytral base associated with an elytral mycangium; elytral bases broadly V-shaped, costate; scutellum minute, convex and slightly raised above elytra; pronotum from dorsal view basic and parallel sided (type 2), from lateral view disc longer than anterior slope (type 7), and pronotal base weakly sinuate.
This species is a probable synonym of M. exsculptus (Eggers, 1927) but has larger denticles along the declivital margin. Additional investigations are needed to assess intraspecific variation and clarify species limits.
West Malaysia (Pahang).
Xyleborus cruralis Schedl, 1975b: 456.
Cnestus cruralis
(Schedl):
Coptodryas cruralis
(Schedl):
Microperus cruralis
(Schedl):
Xyleborus myllus Browne, 1986a: 92. syn. nov.
The holotypes of Xyleborus myllus (
Cambodia, Laos, Thailand.
Xyleborus exsculptus Eggers, 1927: 101.
Coptodryas exsculptus
(Eggers, 1927):
Xyleborus dentipennis Browne, 1983: 558. syn. nov.
M. armaticeps, M. cruralis (Schedl, 1975).
2.12 mm long [1.9–2.0 mm
This species is distinguished from M. cruralis by its smaller size, elytral bases slightly emarginated from sutural margin to interstriae 4 to accommodate mycangial tuft, elytral disc more deeply depressed, deeper posteriorly, declivital summit without a pair of large tubercles on interstriae 1, margins of declivital sulcus begin at interstriae 2, tubercles on declivital margin slender and acute, and punctures on declivity small and indistinct.
Brunei: Kuala Belalong FSC, 116.7°E, 4.34°N, 270 m alt, dipterocarp forest, aerial FIT 4, 17.vi.91, N. Mawdsley (1) (RABC). Thailand: Narathiwat Province, Hala-Bala Wildlife Sanctuary, 5°47'44"N, 101°50'07"E, lowland tropical rainforest, ethanol baited trap, 01.viii.2015, (1) (W. Sittichaya) (WSTC).
Brunei, East Malaysia (Sarawak), Philippines, Thailand.
This species was collected from a seraya log (Shorea sp.) (Dipterocarpaceae) imported to Japan (
The holotype of Xyleborus dentipennis (
Xyleborus pedellus Schedl, 1969: 231.
Coptodryas pedellus
(Schedl, 1969):
The paratype deposited in
Philippines.
Xyleborus spicatulus Browne, 1986b: 667.
This species was previously considered a synonym of Coptodryas dentipennis (= M. exsculptus) by
[Indonesia]: Sumatra, ex Dipterocarpus s. [no further data] [1 specimen in
Indonesia (Sumatra), Laos, East Malaysia (Sabah).
Xyleborus chrysophylli Eggers, 1930: 205.
Coptodryas chrysophylli
(Eggers):
Microperus chrysophylli
(Eggers):
2.52–2.6 mm long (2.56 mm; n = 2) 2.83–2.86× as long as wide [(2.6–2.7 mm long (mean = 2.68 mm; n = 5); 2.6–2.7× as long as wide (
This species strongly resembles M. corporaali and is distinguished by the less strongly sulcate declivity, and declivital strial punctures very large and distinct.
Thailand: Chiang Mai Province, Doi Inthanon National Park, Chomthong District, 18°31'39"N, 98°30'00"E, 1650 msl, Hill evergreen forest, ethanol-baited trap, 01.v.2019 (2) (W. Sittichaya) (WSTC).
Bangladesh, China (Yunnan), India (West Bengal) (
This species is recorded from Cinnamomum (Lauraceae), Chrysophyllum (Sapotaceae), (
Cryptoxyleborus nanus Browne, 1949: 903.
Xyleborus caelator Browne, 1955: 354 (unnecessary replacement name).
Microperus nanus
(Browne):
1.12–1.24 mm (mean = 1.19 mm; n = 6), 2.8–3.0× as long as wide; minute species. This species is distinguished by antennal club type 2, segment 2 visible on anterior side, elytra tapering, declivity obliquely attenuate without posterolateral carina, and elytral posterior margin acute.
Thailand: Narathiwat Province, Hala-Bala Wildlife Sanctuary, 5°47'44"N, 101°50'07"E, lowland tropical rainforest, ethanol-baited trap, 01.xii.2014 (3), 01.iii.2015 (2), (W. Sittichaya) (WSTC).
Brunei Darussalam, East Malaysia (Sabah, Sarawak), West Malaysia.
This species is only known from Dipterocarp hosts including Shorea sp., Hopea ferrea, and Parashorea malaanonan (
Xyleborus quercicola Eggers, 1926: 146.
Microperus quercicola
(Eggers):
Xyleborus izuensis
Murayama, 1952: 16. Synonymy:
1.8–1.92 (mean = 1.85 mm; n = 4) 2.50–2.53× as long as wide [1.8–2.0 mm long (mean = 1.96 mm; n = 5); 2.38–2.86× as long as wide (
Thailand: Narathiwat Province, Hala-Bala Wildlife Sanctuary, 5°47'44"N, 101°50'07"E, lowland tropical rainforest, 01.xii.2017 (1 WSTC) ethanol-baited trap; Songkhla Province, Ton Nga Chang Wildlife Sanctuary, tropical rainforest, 6°59'32.1"N, 100°08'57.8"E, 01.ii.2015 (2), ethanol-baited trap, (all W. Sittichaya) (WSTC).
China (Guizhou, Hong Kong, Jiangxi, Sichuan, Zhejiang), Japan, Russia (Far East), South Korea, Taiwan.
This species is polyphagous and has been recorded from Cinnamomum (Lauraceae) (
1 | Elytral disc broadly, deeply transversely impressed with a saddle-like depression from scutellum to declivital base; declivity deeply sulcate, its margins costate; elytral bases slightly emarginated to accommodate a prominent and dense mycangial tuft | 2 |
– | Elytral disc either medially impressed and appearing humped, or flat, or broadly convex; declivity round or flat or convex; elytral bases not emarginated and mycangial tuft minute, either not readily apparent or lightly setose | 3 |
2 | Elytral base emargination broadly recurved; elytral disc shallowly depressed; declivital summit armed with a pair of large tubercles at interstriae 1; punctures on declivity distinct and broad; larger species, 3.0–3.1 mm | cruralis |
– | Elytral base emargination broadly V-shaped; elytral disc deeply depressed, more deeper posteriorly; interstriae 1 on declivital summit without a pair of large tubercles; punctures on declivital face small and indistinct; smaller species, 2.12 mm | exsculptus |
3 | Posterolateral margin of elytra smoothly rounded, without any indication of a costa or carina | 4 |
– | Posterolateral margin of elytra marked by an elevated costa or carina | 5 |
4 | Elytral lateral margin tapering posteriorly from the middle to apex; elytral apex acute; minute species, 1.12–1.24 mm | nanus |
– | Elytral lateral margin subparallel, broadly tapering posteriorly; apex broadly rounded, not acute; larger species, 1.60 mm | globodeclivis sp. nov. |
5 | Declivity obliquely truncate; posterolateral declivital margin rounded and denticulate | 6 |
– | Declivity rounded; posterolateral declivital margin costate or carinate, with or without granules | 9 |
6 | Declivital interstriae 2 and 3 strongly laterally broadened from base to declivital midpoint and then narrowing towards apex | latesalebrinus |
– | Declivital interstriae parallel from base to apex, never laterally broadened | 7 |
7 | Denticles on declivital summit and margins larger and more sharply acute than those on declivital face | kirishimanus |
– | Denticles on declivital summit of equal size and shape as those on declivital face | 8 |
8 | Denticles on declivital summit as dense as those on declivital face; declivital face opalescent, subshiny | nudibrevis |
– | Denticles on declivital summit denser than those on declivital face; declivital face shagreened, dull | perparvus |
9 | Larger, 2.55–2.95 mm | 10 |
– | Smaller, 1.2–2.1 mm | 12 |
10 | Stout, 1.93–2.19× as long as wide; elytral posterolateral margin strongly carinate and unarmed | fulvulus |
– | Elongate, 2.5–2.9× as long as wide; elytral posterolateral margin costate and granulate | 11 |
11 | Declivital strial punctures very large, distinct | chrysophylli |
– | Declivital strial punctures small, indistinct | corporaali |
12 | Declivity with granules, denticles or tubercles distinctly less abundant than strial punctures | 13 |
– | Declivity with abundant granules or denticles, at least as abundant as strial punctures | 19 |
13 | Elytral disc shallowly transversely impressed with a saddle-like impression | 14 |
– | Elytral disc without a depression | 15 |
14 | Discal impression deeper, antero-posteriorly narrower, with steeper anterior and posterior slopes, strial punctures on impression with rounded granules; interstrial spines on disc behind impression stronger and backwardly hooked | sagmatus |
– | Discal impression shallower, antero-posteriorly broader, with gentler anterior and posterior slopes, strial punctures on impression without granules; interstrial tubercles on disc behind impression moderate with rounded apices pointing dorsally | undulatus |
15 | Declivital tubercles uniformly sized | 16 |
– | Declivital tubercles not uniformly sized, 1–2 pairs of larger tubercles on declivital interstriae 3 | 17 |
16 | Posterolateral declivital margin carinate, unarmed | alpha |
– | Posterolateral declivital margin costate and denticulate | bucolicus sp. nov. |
17 | Declivity steeply rounded, declivital interstriae 1 bearing 1–2 small tubercles on declivital face; larger, 1.9–2.0 mm | recidens |
– | Declivity gradually rounded, declivital interstriae 1 unarmed on declivital face; smaller, 1.66–1.76 mm | 18 |
18 | Declivital interstriae 3 with two pairs of prominent denticles; posterior half of elytral disc rugose with deeply impressed striae and costate interstriae, interstriae bearing strong incurved spines that become more prominent toward declivital summit | serratus sp. nov. |
– | Declivital interstriae 3 with one pair of prominent tubercles; posterior half of elytral disc smooth, striae and interstriae flush, interstriae with a few small tubercles at summit | bidentatus sp. nov. |
19 | Elytral disc convex on basal 1/3, appearing humped in lateral view | 20 |
– | Elytral disc flat, never appearing humped | 22 |
20 | Declivital interstriae densely covered with short semi-erect scales | kadoyamaensis |
– | Declivital interstriae densely covered with long fine, erect hair-like setae | 21 |
21 | Antennal club flat, type 3 with two sutures visible on apical 1/3 of posterior face; larger, declivity smooth, shiny; larger, 1.95–2.0 mm and more elongate, 2.79–2.86× as long as wide | minax |
– | Antennal club obliquely truncate, type 2 with segment 1 almost covering posterior face (Fig. |
nugax |
22 | Antennal club flat, type 3 with two sutures visible on apical 1/3 of posterior face (Fig. |
diversicolor |
– | Antennal club obliquely truncate, type 2 with segment 1 almost covering posterior face; one suture visible on posterior face near apex | 23 |
23 | Declivital interstrial granules dispersed, separated by the width of at least three granules; posterolateral margin of declivity weakly carinate and granulate; interstrial vestiture consisting of short semi-erect bristles, shorter in length than the width of an interstria; smaller, 1.2–1.7 mm | pometianus |
– | Declivital interstrial granules dense, separated by the width of one granule; posterolateral margin of declivity strongly carinate; interstrial vestiture consisting of long semi-erect hair-like setae, longer in length than the width of an interstria (easily abraded); larger, 1.8–2.0 mm | quercicola |
Our study increased the diversity of Microperus to 35 species of which 18 are recorded in Thailand. Since 2010, Microperus has received considerable attention with eight species described and 12 species transferred from a diversity of genera including Xyleborus, Coptodryas and Cyclorhipidion (
Species | First Record | Thai distribution |
---|---|---|
Microperus alpha (Beeson, 1929) |
|
C: Nakhon Nayok; N:Chiang Mai, Phetchabun; N-E: Chaiyaphum, Nakhon Ratchasima, Sakhon Nakhon |
Microperus bidentatus Sittichaya, Smith and Beaver sp. nov. | This publication | S: Songkhla, Trang |
Microperus bucolicus Sittichaya, Smith and Beaver sp. nov. | This publication | S: Nakhon Sri Thammarat |
Microperus chrysophylli (Eggers, 1930) | New record | N: Chiangmai |
Microperus corporaali (Eggers, 1923) | Sittichaya et al. (2012) | S: Chumphon, Nakhon Sri Thammarat |
Microperus diversicolor (Eggers, 1923) |
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S: Nakhon Sri Thammarat |
Microperus exsculptus (Eggers, 1927) | New record | S: Narathiwat |
Microperus globodeclivis Sittichaya, Smith and Beaver sp. nov. | This publication | N: Phayao |
Microperus nanus (Browne, 1949) | New record | S: Narathawat |
Microperus nudibrevis (Schedl, 1942) |
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C: Suphanburi; N: Chiang Mai; N-E: Chaiyaphum; S: Nakhon Sri Thammarat, Surat Thani |
Microperus nugax (Schedl, 1939) |
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C: Chanthaburi; S: Chumphon, Nakhon Sri Thammarat, Surat Thani |
Microperus perparvus (Sampson, 1922) |
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C: Nakhon Nayok; N: Chiang Mai, Mae Hong Son, Nan, Phetchabun, Phitsanulok; N-E: Chaiyaphum, Loei; S: Nakhon Sri Thammarat, Surat Thani |
Microperus pometianus (Schedl, 1939) |
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N: Chiang Mai |
Microperus quercicola (Eggers, 1926) | New record | S: Songkhla, Narathiwat |
Microperus recidens (Sampson, 1923) |
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C: Phetchaburi; N: Chiang Mai, Nan; S: Chumphon, Nakhon Sri Thammarat |
Microperus sagmatus Smith, Beaver & Cognato (2020) |
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S: Chumphon, Nakhon Sri Thammarat, Songkhla, Surat Thani |
Microperus serratus Sittichaya, Smith and Beaver sp. nov. | This publication | S: Songkhla, Narathiwat |
Microperus undulatus (Sampson, 1919) |
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C: Prachuab Khiri Khan, Uthaithani; N: Chiang Mai; N-E: Chaiyaphum; S: Chumphon, Nakhon Sri Thammarat, Songkhla, Surat Thani, Trang |
We are most grateful to Dr. H. Schillhammer (