Research Article |
Corresponding author: Ming Bai ( baim@ioz.ac.cn ) Academic editor: Andrey Frolov
© 2019 Yuan-Yuan Lu, Carsten Zorn, David Král, Ming Bai.
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:
Lu Y-Y, Zorn C, Král D, Bai M (2019) Description of Callistethus hamus sp. nov. (Coleoptera, Scarabaeidae, Rutelinae) from continental Southeast Asia using synchrotron to illustrate the aedeagus. ZooKeys 881: 1-11. https://doi.org/10.3897/zookeys.881.34821
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A new species, Callistethus hamus Lu & Zorn, sp. nov., is described from China, Laos, and Vietnam. Additionally, we used synchrotron (Shanghai Synchrotron Radiation Facility) to scan the aedeagus. The virtual 3D model of the aedeagus is reconstructed and provided.
Anomalini, Callistethus, China, Laos, Vietnam, new species, Rutelinae, 3D models
The genus Callistethus Blanchard, 1851, includes, to date, more than 150 species (
Recently, Micro-CT and synchrotron radiation microtomography techniques have been used in several extant and extinct insect groups, e.g., Formicidae of Hymenoptera (
The morphological terminology follows
The body length was measured from the apex of the clypeus to the apex of the elytra. The length of pronotum was measured in the middle in dorsal view, its width at the greatest width. The ratio of interocular width to head width was measured in dorsal view at greatest width of head and nearest interocular distance.
For observation of morphological structures, some specimens were softened by soaking the aedeagus in detergent for ca. 24 hours. Observations and dissections were carried out under an Olympus SZ61 stereomicroscope and a Zeiss Stemi 2000. The digital images were taken with a Canon 5D digital camera in conjunction with a Canon MP-E 65 mm f/2.8 1–5× Macro Lens, and then stacked by Helicon Focus 5.3.10. All images were edited and adjusted in Adobe Photoshop CS6 Extended. The distribution map was created by QGIS 3.4 software (QGIS Development Team). Coordinates and altitude were assigned for each locality mentioned in the text (material examined in each species). These data were used in the construction of distribution maps (see Fig.
The aedeagus of one specimen was imaged using propagation phase-contrast synchrotron radiation microtomography (PPC-SR-μCT) on the beamline 13W at the Shanghai Synchrotron Radiation Facility (SSRF). The isotropic voxel size was 3.25 μm. The beam was monochromatised at an energy of 14 keV using a double crystal monochromator. To obtain a phase-contrast effect, we used a sample-detector distance (propagation distance) of 300 mm and 900 projections on 180°. The phase retrieval and slice reconstruction were performed using PITRE software. Based on the obtained image stacks, three-dimensional structures of the specimen were reconstructed and virtually dissected with Amira 5.4 (Visage Imaging, San Diego, USA) (see Figs
Type specimens of the new species are provided with one red printed label “Callistethus hamus sp. nov., HOLOTYPE [or] PARATYPE, Lu & Zorn, 2019”.
The material examined is housed in the following collections (curators in parenthesis):
CZPC Carsten Zorn private collection, Gnoien, Germany
FWPC Falei Wang private collection, Chongqing, China
IZAS Institute of Zoology, Chinese Academy of Sciences, Beijing, China (Ming Bai)
MSPC Matthias Seidel private collection, Prague, Czech Republic
NHMUK Natural History Museum, London, United Kingdom (Maxwell W. L. Barclay, Michael Geiser)
NMEC Naturkundemuseum Erfurt, Germany (Matthias Hartmann)
China, Southern Yunnan, 23 km NW of Jinghong, vicinity of Nan Ban, Xishuangbanna [Prefecture], 22°09.49"N, 100°39.92"E, 730 m.
Holotype (HT). CHINA • ♂; Yunnan Province, Dai Autonomous Prefecture of Xishuangbanna, Jinghong City, Na Ban River Watershed National Nature Reserve; 22°09.49'N, 100°39.92'E; 20 May 2008; A Weigel leg.; NMEC.
CHINA • 1 ♀; same data as the holotype • 1 ♂; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 22°09.49'N, 100°39.92'E; 5 Jun. 2008; A. Weigel leg.; NMEC; [Micro-CT specimen] • 1 ♂ 1 ♀; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 22°09.49'N, 100°39.92'E; 5 Jun. 2008; A. Weigel leg.; CZPC • 1 ♀; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 22°09.49'N, 100°39.92'E; 15 Jun. 2008; NMEC • 1 ♀; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 22°09.49'N, 100°39.92'E; 5 Jun. 2008; A. Weigel leg.; NMEC • 1 ♂; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 22°09.49'N, 100°39.92'E; 12 May 2008; A. Weigel leg.; NMEC • 1 ♀; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 22°09.49'N, 100°39.92'E; 16 May 2009; Malaise trap; L.Z. Meng leg.; IZAS IOZ(E)1966878 • 1 ♀; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 22°07.85'N, 100°40.12'E; 26 May 2009; Malaise trap; L.Z. Meng leg.; IZAS IOZ(E)1966879 • 1 ♀; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 22°09.49'N, 100°39.92'E; 16 May 2009; flight interception traps; L.Z. Meng leg.; IZAS IOZ(E)1966880 • 1 ♀; Yunnan Province, Xishuangbanna, Jinghong, Na Ban River Watershed National Nature Reserve; 31. Jul. 2013; FWPC • 1 ♂; Yunnan Province, Menghai, Menghun Town; 21°50.48'N, 100°23.15'E; 4 Jun. 1958; L.Y. Zheng leg.; IZAS IOZ(E)1966104 • 1 ♀; Yunnan Province, Xishuangbanna, Menghai, Menghun Town; 21°50.48'N, 100°23.15'E; 1 Jun. 1958; X.W. Meng leg.; IZAS IOZ(E)1966106 • 1 ♀; Yunnan Province, Xishuangbanna, Menghai, Menghun Town; 21°50.48'N, 100°23.15'E; 4 Jun. 1958; L.Y. Zheng leg.; IZAS IOZ(E)1966107 • 1 ♀; Yunnan Province, Xishuangbanna, Menghai, Mengzhe Town; 21°59.15'N, 100°16.02'E; 8 Jul. 1958; S.Y. Wang leg.; IZAS IOZ(E)1966105.
LAOS • 1 ♂; Vientiane Province, Phou Khao Khoay; 18°24.15'N, 103°02.15'E; 4–17 May 2005; P. Moravec leg.; CZPC.
VIETNAM • 4 ♂♂ 2 ♀♀; Lâm Đồng Prov., Dambri, Bảo Lâm; 11°38.42'N, 107°44.52'E; May 2017; local collector leg.; CZPC • 1 ♀; Lâm Đồng Prov., Bảo Lộc; 11°32.88'N, 107°48.46'E; March 2018; local collector leg.; CZPC • 5 ♂♂ 1 ♀♀; Lâm Đồng Prov., Bảo Lộc; 11°32.88'N, 107°48.46'E; March 2018; local collector leg.; CZPC • 1♂ 1 ♀; Lâm Đồng Prov., Bảo Lộc; 11°32.88'N, 107°48.46'E; March 2017; local collector leg.; MSPC.
Description of holotype (♂). Body shape elongate ovoid, convex.
Colour. Head including antenna orange-brown, with two small black spots on vertex; pronotum orange-brown with two moderately large black spots in the middle of each side; an additional longitudinal stripe near the lateral margin (not reaching anterior and posterior margins) separating the yellow sides from the orange disc (Figs
Holotype of Callistethus hamus Lu & Zorn, sp. nov. 1–3 habitus 1 dorsal view 2 ventral view 3 lateral view from left 4 head and pronotum 5 propygidium and pygidium 6–8 aedeagus 6 dorsal view 7 lateral view from right 8 ventral view 9 label. Key: Sc. 1, Scale bars: 5 mm (1–3); Sc. 2, 5 mm (4, 5); Sc. 3, 1 mm (6–8).
Head.
Clypeus subtrapezoidal, anterior angles rounded; anterior margin weakly reflexed, very densely, transversely rugo-punctate; frons rugo-punctate, with very shallow impression in the middle, confluently punctate at sides; vertex finely and sparsely punctate in the middle, more coarsely punctate laterally; ratio interocular width/width of head approximately 0.71; antennal club longer than antennomeres 1–6 combined (Figs
Pronotum
approximately 1.89 times wider than long; sparsely and finely punctate, punctures very fine on disc, becoming gradually larger toward the sides; surface with additional micropunctures; anterior angles sub-rectangular; posterior angles obtuse; broadest at base; sides evenly curved in the middle, straight and strongly converging before anterior angles; sides very slightly sinuate near posterior angles; basal marginal line only present near posterior angles; anterior marginal line indistinct in the middle (Fig.
Scutellum
subtriangular, slightly broader than long, finely and sparsely punctate (Fig.
Elytra
regularly striate; primary striae and secondary stria of subsutural interstice sulcate in posterior half, therefore intervals flat in anterior half and gradually more convex posteriad; strial punctation distinct, coarse; 2nd and 3rd interstices each with an indistinct row of punctures; elytral surface with additional sparse micropunctation; humeral umbone and apical protuberance rather prominent; epipleuron broad near humerus, ending approximately at the middle of elytron; posterior margins evenly, separately rounded; apico-sutural angle forming small dent (Fig.
Pygidium
convex; apex broadly rounded; moderately densely, coarsely punctate; apex with several long, erect brownish setae (Fig.
Ventral thoracic surface
smooth (Fig.
Meso-metaventral process
very long, reaching middle of procoxae; projecting upward in lateral view; apex acute (Fig.
Abdominal ventrites
with transverse row of rather sparse brown setae (usually only in lateral part); ventrites 1 and 2 carinate laterally (Figs
Legs.
Mesofemur with two bands of long brown setae: one along anterior margin; another transverse row of punctures parallel to posterior margin. Protibia bidentate, rather slender; proximal tooth short, situated close to the rather short, weakly outwards curved apical tooth; inner spur short, articulated in opposite to proximal tooth. Metatibia strongly fusiform; protarsomere 5 shorter than tarsomeres 1–4 combined in all legs; inner protarsal claw slightly widened and deeply incised apically, lower margin with obtuse angle basally, upper branch spiniform; outer mesotarsal claw long, curved, deeply incised at apex, upper branch spiniform; metatarsal claws somewhat unequal, outer claw distinctly broader and longer than inner (Figs
Aedeagus.
Parameres short, with the hook-like apex in lateral view. See Figs
Female. Abdominal ventrites 4–6 with extensive yellow markings. Apical tooth of protibia long and somewhat spatulate; protarsus articulated slightly basally of level of proximal tooth; inner spur long; protarsomere 1 as long as combined length of protarsomeres 2–4; antennal club short, only slightly longer than antennomeres 2–6 combined.
Total body length 11.5–14.4 mm (HT 11.8 mm), total body width 6.5–8.4 mm (HT 7.5 mm).
Vertex with or without two black spots. Elytral spots vary slightly in shape and size. The extend of black markings of the ventral side variable. The secondary longitudinal rows of punctures in interstices 2 and 3 sometimes distinct until the posterior half. Shape of parameres very consistent (Figs
Callistethus hamus sp. nov. resembles several other, similarly coloured South East Asian species of this genus. The reddish colour combined with black markings is also found in C. maculatus (Guérin-Méneville, 1834), C. picturatus (Candèze, 1869), C. rachelae (Arrow, 1917), C. spiniferus (Ohaus, 1915), and C. stolidopygus (Ohaus, 1915). The new species is most similar to C. rachelae, which also has only two black spots on the pronotum, not four as all other red species (Figs
Holotype of Callistethus rachelae (Arrow, 1917). 10–12 habitus 10 dorsal view 11 ventral view 12 lateral view from left 13 head and pronotum 14 propygidium and pygidium 15–17 aedeagus 15 dorsal view 16 lateral view from right 17 ventral view 18 label. Key: Sc. 1. Scale bars: 5 mm (10–12); Sc. 2, 5 mm (13, 14); Sc. 3, 1 mm (15–17).
The specific epithet refers to the hook-like shape of the parameres of the new species.
Specimens collected in the Naban River Watershed National Nature Reserve by Lingzeng Meng and Andreas Weigel were collected with cross-window traps in the tree canopy and malaise trap.
We found one female specimen in the collection of the IZAS, collected at Jinghan Town, Dehong prefecture, Yunnan, which could represent the first record of C. rachelae in China. The collecting locality is very close to the type locality of Callistethus rachelae in neighbouring Myanmar (“Bhamo”, see Fig.
In the present study the synchrotron technology was used for the first time to study a Rutelinae species. Normally, the original data of 3D information need to be present in some specific software (like Amira and Maya), which require a higher hardware configuration. Obviously it will limit the widespread use of this technology by taxonomists to some extent. In this study, we found that the structure complexity of the aedeagus of the here examined Rutelinae is relatively low and can be obtained as 3D model in pdf format containing about 20Mb (Appendix
Unfortunately, in this study, internal structures like the endophallus are not clearly visible in the 3D model. The synchrotron and Micro-CT technology require a dried out specimen and are suitable for sclerotised structures, while membranous structures like the endophallus will be out of shape during the operating steps. Therefore, it will be difficult to obtain the 3D structure of the endophallus. The disadvantages of this technology include also its high cost and the fact that the procedure is time-consuming.
In summary, the synchrotron and Micro-CT technology have great potential for wide use in the taxonomy of the Rutelinae and other insect groups, because it provides accurate morphological information of 3D structures. But the shortcomings of this technology are still obvious. Therefore, the innovation of new techniques that aid in the visualisation of microscopic anatomical structures is needed. The recently invented LED-SIM (DMD-based LED-illumination structured illumination microscopy) facilitates the acquisition of nano- and micro-3D structures of small organisms in a high-resolution format (500 nm in the XY-plane and 930 nm along the Z-axis) (
The authors wish to express their sincere gratitude to Falei Wang (Chongqing) for providing material from his collections for this study, and to Haidong Yang (IZAS) for helpful technical support in 3D reconstruction. Moreover, we are very grateful to the collection managers and curators Maxwell WL Barclay and Michael Geiser (NHMUK) and Matthias Hartmann (NMEC) for preparing loans of type material and unidentified ruteline material for examination. We thank the Shanghai Synchrotron Radiation Facility (BL13W1) for beam-time access. This research was supported by the National Natural Science Foundation of China (No. 3181101902). The work of DK was funded by Chinese Academy of Sciences President’s International Fellowship Initiative (Grant No. 2019VBC0012).