﻿New species and new records of Scolytoplatypus Schaufuss (Curculionidae, Scolytinae) from China, and resurrection of Scolytoplatypussinensis (Tsai & Huang, 1965) as a distinct species

﻿Abstract This study describes two new species, Scolytoplatypuswugongshanensis Liao, Lai & Beaver, sp. nov. and S.skyliuae Liao, Lai & Beaver, sp. nov., reinstates S.sinensis (Tsai & Huang, 1965) from synonymy with S.mikado (Blandford, 1893), and records five species for the first time from China, S.brahma Blandford, 1898, S.curviciliosus Gebhardt, 2006, S.minimus Hagedorn, 1904, S.ruficauda Eggers, 1939, S.samsinghensis Maiti & Saha, 2009, and three from mainland China, S.blandfordi Gebhardt, 2006, S.calvus Beaver & Liu, 2007, S.pubescens Hagedorn, 1904. A key to the males of Scolytoplatypus species in China is given. Genetic data from four genes indicate a rather isolated position for both new species, although their genetic relationship to each other was close.


Introduction
The genus Scolytoplatypus was erected for a single species, S. permirus Schaufuss, from Madagascar (Schaufuss 1891). To date, there are approximately 50 species reported in the world, most of which are distributed in the Afrotropical and Oriental regions, and a few in the temperate areas of Japan to India (Wood and Bright 1992;Skidmore 1997, 2002;Beaver and Liu 2007;Maiti and Saha 2009;Jordal 2013Jordal , 2018. Approximately 16 species are known from the Afrotropical region, including 12 or 13 species on the African continent and three species in Madagascar (Jordal 2018). Beaver and Gebhardt (2006) reviewed the genus in the Oriental region and recognised 28 species, six of which are known from China. Beaver and Liu (2007) described a new species S. calvus Beaver & Liu, from Taiwan. Knížek (2008) described a new species, S. zahradniki Knížek, from Shaanxi, China, and S. darjeelingi Stebbing was listed for Hunan, Sichuan, and Yunnan in Knížek (2011). The following nine species are currently recognised to occur in China: S. blandfordi Gebhardt, 2006;S. calvus Beaver & Liu, 2007;S. darjeelingi Stebbing, 1914;S. mikado (Blandford, 1893); S. pubescens Hagedorn, 1904;S. raja Blandford, 1893;S. tycon Blandford, 1893;S. superciliosus Tsai & Huang, 1965 and S. zahradniki Knížek, 2008. S. blandfordi, S. calvus and S. pubescens were found only in Taiwan, China.
All known species of Scolytoplatypus are ambrosia beetles (Beaver and Gebhardt 2006) which cultivate fungi in a gallery system as the only food source for larvae and adults. The females of most species have a unique mycangial structure for carrying fungal spores, located on the pronotum. However, this is absent in some species (Beaver and Gebhardt 2006), and the mechanism of ambrosial fungal transport is not known in these species (Mayers et al. 2020). In addition to the structural differences of the pronotum, the two sexes also show differences in the morphology of the frons, prosternum, protibia, and elytral declivity. The beetles are monogamous. The gallery system is started by the female. It consists of an entrance gallery leading to one or more circumferential branches in one transverse plane. The male joins the female soon after the beginning of maternal gallery construction, and mating occurs at the gallery entrance. The male remains in the entrance hole to prevent the entry of predators and helps with removal of the faecal material (Browne 1961). The eggs are laid in individual niches above and below the gallery. The larvae develop in individual barrelshaped cells, feeding on the ambrosial fungus growing on the walls, and enlarging the cell as they grow. The fully grown larva pupates in the cell, and the new adult emerges into the gallery and leaves by the original entrance hole (Beeson 1961;Browne 1961;Beaver et al. 2014) In recent years, we have made extensive collections of beetles in China. In this paper, we describe two new species of Scolytoplatypus from these collections and provide a DNA-based phylogenetic analysis of several Chinese and other Scolytoplatypus species. We also record eight species from mainland China for the first time and provide a key to the males of the Chinese species. Collections were made in Jiangxi, Yunnan, Sichuan, Zhejiang, Fujian, and Chongqing in China. The samples were immediately preserved in tubes containing 99.9% ethyl alcohol, which were stored at -20 °C for DNA extraction and examination. We used a stereoscopic microscope (Cnoptec SZ680) to examine the beetles. Photographs were taken with Keens Ultra-Depth of Field 3D Microscope (VHX-600). All photographs were further adjusted and assembled with Adobe Photoshop CS6. All measurements were made on ten specimens of both sexes chosen to show the entire variability range. The body length was measured from the anterior pronotal margin to the elytral apex. Finally, we also provide references to published illustrations of several species, which can be found on the Internet or in publications. DNA was extracted from the adult head. The total genomic DNA was extracted from each individual using the Ezup Column Animal Genomic DNA Purification Kit (Sangon Biotech Co. Ltd). Amplification of four gene fragments (COI, EF-1α, CAD, 28S) was made by PCR, using primers and cycling conditions previously described (Jordal et al. 2011). The PCR products containing target bands were sent to Sangon Biotech Co. Ltd (Shanghai, China) for purification and sequencing, and the sequences were analysed using the software DNAstar. Additional information on the Scolytoplatypus material was collected by the authors in China or downloaded from NCBI (The National Center for Biotechnology Information) (Table 1). Concatenated DNA sequence data from Jordal (2013) were analysed in MrBayes v. 3.2.6, Partitions and models were estimated by PartitionFinder 2 and ModelFinder respectively in Phylo-Suite, GTR+G were selected for each partition. 10 million generations were run, with 25% of the generations as burn-in, PSRF close to 1.0 and standard deviation of split frequencies below 0.01 were accepted (Lai et al. 2021). Maximum likelihood (ML) analyses were conducted with IQ-TREE. The optimal model of molecular evolution found by ModelFinder each partition based on the Bayesian information criterion (BIC) scores. Each partition was as follows: 28S = GTR+I+G, CAD = TVMEF+I+G, COI= GTR+I+G, EF-1α = TRN+I+G. Clade support was assessed by 5000 bootstrap pseudoreplicates of the combined data set.
Diagnosis. The morphology of the species, especially the male prosternum, indicates that it is more closely related to S. blandfordi Gebhardt. Both species have the   Table 2. Description. Male. Body. Length 3.8-4.2 mm (3.8 mm in holotype), 2.00-2.21× as long as wide (2.00 in holotype); dark brown to black in mature specimens, shiny, elytra slightly darker. Whole body covered with fine, yellowish hairlike setae.
Frons. Shallowly concave, slightly flattened above epistoma, with short and shallow depressions on its sides and a fine median impressed line on upper half, lower flattened part without punctures and setae, upper part with minute punctures bearing fine, erect, yellowish setae, margin with two brushes of long golden hairlike setae above the eye, widely separated dorsally, curved towards centre of frons and extending nearly to epistoma; a few long setae on frontal margin at level of antennal insertions.
Antennal club. 2.1-2.2× as long as wide, elongate and triangular, widest near the base, acuminate, densely covered with short appressed setae, anteroventral margin in basal half with a row of seven long, erect setae, thickened and curved at tips, apex with a few long, erect setae.
Pronotum. 0.81-0.87× as long as wide (0.81 in holotype), widest in the middle of its length, anterior margin with distinct median emargination, posterior margin bisinuate, slightly produced in the middle, posterolateral corners approximately rectangular, dorsal surface shining, minutely, moderately densely, rather irregularly punctured except for small, median, impunctate area just anterior to middle of pronotum, corresponding to site of mycangium in female, vestiture of very fine and short hairlike setae. Anteroventral angles with a deep, oval fovea, extending to anterior but not ventral margin of pronotum.
Prosternum. Median part raised in a triangle, its apex anterior not reaching the anterior margin, anterior quarter shining, smooth, the extreme tip sharply pointed, posterior three-quarters of triangle more coarsely granulate. Each granule with a moderately long, backwardly directed seta; anterior margin of prosternum with two symmetrical, divergent, triangular, translucent processes. Male frons with two distinct brushes of long hairs on the margins.
Male frons with a sparse fringe of long hairs.
Male frontal margin with a fringe of hairs dorsally extending to vertex. Anterior processes of male prosternum Processes short, bluntly rounded at tip, lying parallel to anterior margin.
Processes inserted just behind anterior margin, broadly triangular, diverging at an angle of ~ 90°E lytral disc Angularly separated from declivity Evenly curving into declivity Evenly curving into declivity Elytral declivity Male declivity with small spines present on interstriae 1-7.
Female declivity with long, dense pubescence.
Procoxa. Slightly flattened anteriorly, rugose, a group of longer setae near the anterior margin; posteriorly with a small, raised, granulate process bearing a loose brush of long, medially curved, coarse, yellow setae.
Abdomen. Ventrites shallowly, densely punctured, each puncture with a fine, backwardly directed seta, setae variable in length; last visible ventrite with a band of long golden setae directed posteriorly.
Female. (Fig.1G, H). Length 4.0-4.6 mm (4.0 mm in allotype), 2.11-2.42× as long as wide (2.11 in allotype). Similar to male, slightly larger. Frons triangularly impressed above epistoma, otherwise convex, matt, moderately densely, finely punctured, reticulate between punctures which bear fine, white, erect, hairlike setae, median cranial suture prominent, extending as a fine line to apex of frontal impression. Antennal scape shorter and antennal club oval, shorter and wider than male, rounded at apex, without a row of erect setae antero-ventrally. Pronotum generally as male, but with oval mycangial pit surrounded by erect yellow setae in midline anterior to middle; anteroventral fovea absent. Prosternum a flattened plate lacking specific characters. Procoxae flattened without a process or brush of hairs posteriorly. Elytra generally as in male, but interstrial spines on declivity smaller.
Host. Fagaceae sp. Distribution. China: Fujian (Nanping) and Jiangxi (Ganzhou, Pingxiang). Biology. Specimens were collected from small branches (2.0-2.3 mm diameter) of broadleaved trees, including an unidentified species of Fagaceae. The maternal gallery penetrates almost through the whole diameter of the twig, and pupal chambers lie perpendicular to the maternal gallery.

Scolytoplatypus skyliuae
Diagnosis. Like S. wugongshanensis, this species is similar to S. blandfordi in its general form and in the structure of the prosternum. The males of those can be distinguished using the characters given in Table 2.
Frons. Strongly concave, slightly flattened above epistoma, with small, shallow depressions at sides, surface minutely reticulate, finely, sparsely punctured, punctures with erect, fine hairs, median line extending ~ 1/4 of frontal height, margins with a row of longer setae below eyes, above eyes a fringe of long, golden setae, extending to vertex, and inwardly curved to middle of frons.
Antennal club. Ovate, ~ 1.7× longer than wide, widest ~ 1/4 length from base, apex narrowly rounded, densely covered with short, appressed setae, anteroventral margin with a row of five or six long erect setae with thickened and incurved tips.
Pronotum. 0.94-1.00× as long as wide (0.94 in holotype), widest at middle, narrowed posteriorly, anterior margin with distinct median emargination, posterior margin bisinuate, slightly produced in the middle, posterolateral corners approximately rectangular, surface smooth, shining, with fine, shallow, irregularly spaced punctures, more densely placed towards posterior margin, bearing fine setae. Anteroventral angles with a deep, oval fovea, not extending to anterior or ventral margins of pronotum.
Prosternum. Median part raised in a triangle, its apex anterior, sharply pointed, not reaching the anterior margin, anterior tip shining, impunctate, posterior part rugose, shallowly punctured, the punctures with appressed, backwardly directed setae. Two symmetrical, triangular, translucent processes diverging at an angle of ~ 90°, inserted just behind anterior margin.
Elytra. 1.10-1.16× as long as wide (1.16 in holotype), 1.31-1.47× as long as pronotum (1.37 in holotype), clearly wider than pronotum, sides almost parallel, widest in posterior part, then strongly converging to rounded apex; disc of elytra shining with confused, fine punctures, more closely placed towards declivity, pubescence fine and short, semi-erect, posterior; disc evenly rounded into declivity; declivity convex, densely, finely punctured, sutural interstriae weakly raised in mid-declivity bearing a row of small pointed granules, striae 1 and 2 and interstriae 2 slightly impressed, interstriae 2 without granules except for one or two at top of declivity, interstriae 3 slightly raised with a row of pointed granules, interstriae 4 and 5 with a few scattered granules, interstriae 8 finely carinate posteriorly, the carina extending to the elytral apex, with a row of minute sharply pointed granules posterolaterally; pubescence denser and longer on the declivity then elytral disc .
Abdomen. Ventrites shallowly, densely punctured, each puncture with a fine, backwardly directed seta, setae variable in length; last visible ventrite with a band of long golden setae directed posteriorly.
Female. (Fig. 2G, H). Length 4.4-4.8 mm (4.6 mm in allotype), 2.32-2.53× as long as wide (2.42 in allotype). Similar to male, but slightly larger. Frons convex, a weak, triangular impression above epistoma, surface finely reticulate, sparsely, finely punctured, punctures bearing short, fine, erect setae, median cranial suture extending as a median line to apex of triangular impression. Antennal scape shorter than in male, antennal club oval, shorter and wider than male, without a row of erect setae antero-ventrally. Pronotum generally as male, but with a median oval mycangial pit surrounded by erect yellow setae anterior to middle; anteroventral fovea absent. Prosternum a flattened plate lacking specific characters. Procoxae flattened without a posterior process. Elytral declivity generally as in male, but sutural interstriae very slightly raised, and impression lateral to it obsolescent, interstrial granules minute.
Host. Castanopsis fargesii Franch. (Fagaceae). Distribution. Fujian (Wuyishan) and Jiangxi (Shangrao). Etymology. The species is named for Dr. Sky Liu Lan-Yu for her contributions to the systematics and biology of wood-boring beetles.
Molecular data. The tree topology resulting from the Bayesian and ML analyses of the combined molecular data were near identical and all nodes except one received high support (Fig. 3). Additionally, S. wugongshanensis and S. skyliuae formed a sister clade to the Asian species of Scolytoplatypus. Phylogenetic analysis indicates a rather isolated position for both new species, although their genetic relationship was close.  Figure 4 Scolytoplatypus sinensis Tsai & Huang, 1965: 121. Taxonomy. This species has been considered to be a synonym of S. mikado Blandford (Wood 1989;Beaver and Gebhardt 2006). Having now examined a larger number of specimens from various provinces of China (including Taiwan), we believe it to be a distinct species. Park (2016) in an unpublished thesis came to the same conclusion based on morphology and DNA differences, but has not officially published his results. Therefore, we resurrect the species here. The species was previously recorded from China (Fujian, Sichuan), Korea and Taiwan (Tsai and Huang 1965;Park 2016). Park (2016) also includes Japan, but we have seen no specimens from that country, nor any published records. Distribution. China (Chongqing, Fujian, Jiangxi, Sichuan, Yunnan, Zhejiang) Remarks. The characters given by Tsai and Huang (1965) to distinguish the species from S. mikado are not entirely reliable, showing some degree of intraspecific variation, and their figures can be misleading. The male of S. sinensis can be distinguished from S. mikado by the following characters (S. sinensis given first): Prosternum strongly humped anteriorly when viewed from below vs. anterior part of prosternum almost flat or weakly raised, never strongly humped; anterior processes of prosternum directed forwards, diverging by up to 60° vs. anterior processes directed more laterally, diverging at an angle of 60-120°; procoxae with a dense brush of 15-20 long, erect setae anteriorly near the inner margin vs. procoxae with only a few (4-7) long, erect setae anteriorly; smaller size, male 3.0-3.2 mm long vs. male 3.3-3.6 mm long. It has not been possible to find characters which will reliably separate the females of the two species if they are not collected in association with males. The suggestion of Tsai and Huang (1965) that there is a difference in the position of the mycangial pore on the dorsal surface of the pronotum is not borne out by the examination of numerous specimens of both species.

Scolytoplatypus calvus Beaver & Liu
Diagnosis. S. calvus is most closely related to S. mikado and S. raja, but is smaller than either, and may be distinguished by the characters given in the key.
Host. Not known. Diagnosis. The species most closely resembles S. parvus and S. reticulatus. The male can be distinguished from S. parvus by the absence of granules and conspicuous white hairs on the lower part of the elytral declivity, and from S. reticulatus by the lack of teeth on the interstriae at the summit of the elytral declivity, and the impressed elytral striae. The females of all three species lack a mycangial pore on the pronotum. The female of S. curviciliosus can most easily be distinguished from S. parvus by its slightly larger size (2.0-2.1 mm vs. 1.8-1.9 mm in S. parvus), and the more strongly angulate posterior angles of the pronotum, and from S. reticulatus by the non-impressed elytral striae, obsolescent on the declivity, and flat, not convex, interstriae (Beaver and Gebhardt 2006).

Scolytoplatypus minimus Hagedorn
Diagnosis. The male appears to be related to S. reticulatus which has a similar prosternum (compare figures 1K and 1L in Beaver and Gebhardt 2006). The females are also very similar, but the female of S. reticulatus lacks the typical mycangial pore on the pronotum. Host. Recorded from species of Alnus (Betulaceae), Cornus (Cornaceae), and Prunus (Rosaceae) (Beeson 1961), Cinnamomum (Lauraceae) (Beaver and Browne 1975), and Acrocarpus (Leguminosae) (Saha and Maiti 1996). Evidently polyphagous. In Thailand, the species was found in smaller branches (1-2 cm diameter) of Cinnamomum iners Reinw. ex Bl. than those attacked by S. raja and S. pubescens (Beaver and Browne 1975). Figure 8 Scolytoplatypus pubescens Hagedorn, 1904: 123. Scolytoplatypus pubescens kabakovi Axentjev, 1992. Diagnosis. S. pubescens is most closely similar to S. superciliosus and S. zahradniki, but can be distinguished by the characters given in the key.

Scolytoplatypus pubescens Hagedorn
Host. The species is known to attack at least 12 different families of trees (Beaver and Gebhardt 2006). Carya cathayensis Sarg. (Juglandaceae) is recorded here as a new host.
Diagnosis. The species is most closely similar to S. wugongshanensis. but can be distinguished by the characters given in the key.
Host. Not known.

Distribution. India (West Bengal). New to China (Yunnan).
Diagnosis. The species is very close to S. eutomoides Blandford, but differs from it on the basis of the following characters of the males (S. samsinghensis given first): 1. striae 1 and 2 marked up to the lower half of declivity, little elevation at interstriae 1 and 3, on or near the elevation with fairly large granules vs. striae 1 and 2 marked up to upper half of declivity and lower half with smaller granules; 2. punctures on pronotum rather deep vs. punctures on pronotum, rather shallow; 3. strial groove marked by elongate and confluent punctures vs. strial groove devoid of any distinct punctures; 4. frontal hairs restricted only towards vertex vs. upper half of frons with hairs (Maiti and Saha 2009

Conclusions
Although the biology of the two new species has not been systematically studied, it can be expected to be similar to that of other species of Scolytoplatypus (Beaver and Gebhardt 2006). Scolytoplatypus is a very characteristic genus of ambrosia beetles, and even the smallest of the known species are larger than the average wood boring beetle (Jordal 2018). The species of Scolytoplatypus show marked sexual dimorphism. Some morphological characteristics of Asian species, as opposed to African species, differ between the sexes, e.g., antenna, pronotum, male prosternum. The characters of the male prosternum are particularly useful at specific level in the Oriental species (Beaver and Gebhardt 2006). The total number of species, host plants and distribution of Scolytoplatypus in China are still unclear and need further study. Many other species have been reported in neighbouring countries of China, which still have not been found in China. In addition, new species of Scolytoplatypus are being described one after another (Beaver and Gebhardt 2006;Browne 1971;Jordal 2013Jordal , 2018Knížek 2008), indicating quite strongly that many more species remain to be discovered, especially on the mainland China.