#ZooKeys ZooKeys 1218: 35-47 (2024) DOI: 10.3897/zookeys.1218.133287 Research Article Taxonomic notes on the genus Chaitoregma (Hemiptera, Aphididae, Hormaphidinae), with description of a new species from China Yizhe Wang™, Xiaolei Huang'® 1 State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China Corresponding author: Xiaolei Huang (huangx/@fafu.edu.cn) OPEN Qaccess Academic editor: Colin Favret Received: 28 July 2024 Accepted: 4 October 2024 Published: 14 November 2024 ZooBank: https://zoobank. org/8A7B431E-514B-4B2B-B611- 645A48B229B6 Citation: Wang Y, Huang X (2024) Taxonomic notes on the genus Chaitoregma (Hemiptera, Aphididae, Hormaphidinae), with description of a new species from China. ZooKeys 1218: 35-47. https://doi.org/10.3897/ zookeys.1218.133287 Copyright: © Yizhe Wang & Xiaolei Huang. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International - CC BY 4.0). Abstract A new aphid species, Chaitoregma kirlia sp. nov., from Fujian and Guangdong, China, is described, which feeds on bamboo. The diagnostic morphological characteristics of the new species are described and illustrated. A key to apterous viviparous females of Chaitoregma species is provided. The COI barcode sequence of this new species is also provided. Due to its unique morphological characteristics, the diagnosis of the genus has been revised. Other species within the genus are also reviewed and discussed. Key words: Chaitoregma, China, Hormaphidinae, new species, taxonomy Introduction The aphid genus Chaitoregma was established by Hille Ris Lambers and Basu in 1966, with Oregma tattakana Takahashi, 1925 as the type species. This small genus belongs to the tribe Cerataphidini (Aphididae, Hormaphidinae). Currently, Chaitoregma comprises only two species and one (non-nominotypical) subspe- cies: C. tattakana tattakana (Takahashi, 1925), C. tattakana suishana (Takahashi, 1929), and C. aderuensis (Takahashi, 1935) (Eastop and Hille Ris Lambers 1976; Remaudiére and Remaudiére 1997; Fang et al. 2006; Favret 2024). These spe- cies were originally discovered on Taiwan Island, China, where they feed on vari- ous bamboo species, such as Phyllostachys pubescens, Yushania niitakayamen- sis, and Bambusa spp. (Takahashi 1925, 1929, 1931, 1935; Qiao et al. 2018). The genus Chaitoregma is characterized by cylindrical frontal horns with round- ed tips and nymphs that exhibit blunt frontal horns from birth. The pronotum is fused to the head; the mesonotum, metanotum, and abdominal tergites | and VIII remain free, whereas the other segments are completely fused without distinct sutures. Roundish to irregular stippled wax facets can be found everywhere on the dorsal surface of the body, but wax glands are not present in localized groups (Hille Ris Lambers and Basu 1966; Basant and Ghosh 1985; Tao 1991). In this study, a new species, Chaitoregma kirlia sp. nov., is described, found on bamboo in Fujian and Guangdong, China. A key to apterous viviparous fe- males of Chaitoregma species is provided. Other species within the genus are reviewed and discussed. 35 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma Materials and methods Field sampling The specimens of the new species were collected from Wuyishan Mountain, Fujian Province, China on August 2, 2016, and Mount Lianhuashan, Guangdong Province, China on July 16, 2024. During the fieldwork, photographs of live individuals were taken using a digital camera (Canon EOS 7D plus Canon EF 100 mm f/2.8L Macro IS USM Lens). Specimens of C. tattakana tattakana were collected from Kunming, Yunnan Province, China on November 9, 2017. All samples were preserved in 95% ethanol and kept at -80 °C for further morphological measurement and molecular experiments. Morphological description Aphid terminology and the morphological measurements used in this paper fol- low Cheng and Huang (2023) (Table 1). Specimens were examined and measure- ments and images were taken by using Nikon SMZ18 stereomicroscope. The measurements and the micrographs of mounted specimens were performed Table 1. Biometric data (mean, range) of Chaitoregma kirlia sp. nov. and Chaitoregma tattakana tattakana. Chaitoregma kirlia sp. nov. Chaitoregma tattakana Apterous Part Apterous vivipara (n = 8) vivipara (n = 7) Mean Range Mean | Range Length (mm) BL 1.164 1;012=-1,372 W322 1.209-1.395 BW 0.690 0.624-0.789 0.734 0.645-0.852 WA 0.198 0.187-0.210 0.236 0.230-0.241 Ant. | 0.031 0.025-0.037 0.033 0.030-0.040 Ant. II 0.028 0.025-0.030 0.035 0.029-0.038 Ant. III 0.070 0.064-0.073 0.089 0.087-0.094 Ant. III.WD 0.029 0.027-0.033 0.029 0.027-0.030 Ant. IV 0.047 0.040-0.052 0.056 0.052-0.063 PT 0.022 0.018-0.027 0.020 0.016-0.025 HF 0.225 0.201-0.254 0.273 0.245-0.286 HF_WD 0.059 0.053-0.069 0.056 0.054-0.058 HT 0.288 0.262-0.307 0.362 0.340-0.384 HT_WD 0.036 0.031-0.040 0.032 0.030-0.035 2HT 0.071 0.065-0.079 0.092 0.088-0.101 SIPH_DW 0.029 0.024-0.033 0.032 0.028-0.038 Cauda 0.034 0.030-0.046 0.039 0.030-0.051 Cauda_ BW 0.065 0.058-0.070 0.078 0.072-0.086 URS 0.047 0.040-0.051 0.053 0.051-0.056 URS_BW 0.048 0.042-0.055 0.041 0.039-0.044 MF 0.038 0.029-0.047 0.041 0.030-0.050 FH 0.045 0.039-0.054 0.059 0.053-0.062 FH_BW 0.033 0.028-0.048 0.035 0.032-0.041 Setae on dorsum head 0.059 0.050-0.066 0.090 0.079-0.112 Setae on abd. tergites | 0.048 0.035-0.059 0.087 0.056-0.113 Setae on abd. tergites VIII 0.060 0.042-0.072 0.081 0.062-0.096 Setae on Ant. Ill 0.026 0.020-0.045 0.032 0.026-0.036 Distance between the apex of horns 0.121 0.109-0.135 0.103 0.098-0.110 Setae on hind tibia 0.037 0.033-0.044 0.058 0.050-0.065 ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 36 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma Chaitoregma kirlia sp. nov. Chaitoregma tattakana Apterous Part Apterous vivipara (n = 8) vivipara (n = 7) Mean Range Mean Range No. of setae URS 6 6-7 6 6 Ant. | 1 $-2 2 lea? Ant. Il 2 2-3 2 2 Ant. Ill 4 3-6 4 4-5 Ant. IV 2 $72 1 1 PT 4 2-5 4 375 HF 15 10-19 ee 24-21 HT 22 18-28 24 21-28 CAUDA 5 OFF 10 8-12 AP 11 10-13 3 i Foal lis) GP 11 9-19 14 11-18 GONA 10 9-13 12 10-15 Around SIPH 5 4-6 4 3-4 FH 8 6-12 F 6-7 Dorsum head 18 15=20 26 25-28 Dorsum mesonotum 11 7-12 13 11-14 Dorsum metanotum A 8-13 14 2>17, Dorsum tergites | 9 2712 15 1316 Dorsum tergites VIII 11 8-16 TZ 15-19 Ratio (times) BL/BW 1.69 1.60-1.80 1.81 1,59=2:01 WA/BL 0.17 0.14-0.20 0.18 0.17-0.19 HT/BL 0:25 0.22-0.26 0.27 0.25-0.3 HF/BL 0.19 0.18-0.21 0.21 0.18-0.23 PT/WA 0.11 0.09-0.13 0.09 0.07-0.10 Ant. III/WA 0.36 0.32-0.39 0.38 0.36-0.40 PT/Ant.lV 0.48 0.39-0.68 0.37 0.27-0.48 URS/URS_BW 0.96 0.78-1.04 1.28 1.16-1.44 URS/2HT 0.66 0.60-0.75 0.56 0.54-0.58 Cauda_BW/Cauda 1.88 199222716 2.10 1.53=2,87 HF/Ant. III 3.20 2.79-3.86 3.06 Vue Spa BAe) 2HT/Ant. Ill 1.02 0,92=1s13 1.06 0.98-1.16 URS/Ant. III 0.66 0.56-0.74 0.59 0.57-0.63 using a computer-connected Nikon set: Nikon Eclipse Ci-L upright microscope, 16 MP digital camera with 0.55 x adapter and imaging software NIS-Elements D v. 4.60.00. The unit of measurement in this paper is millimeter (mm). The following abbreviations have been used: BL, body length; BW, body width; WA, whole length of antenna; Ant. |, Ant. Il, Ant.IIl, Ant. IV, for antennal segment 1, Il, III, IV, respectively; Ant. III_WD, the widest diameter of Ant. III; PT, processus terminalis; HF, hind femur; HF_WD, the widest diameter of HF; HT, hind tibia; HT_WD, the widest diameter of HT; 2HT, second hind tarsal segment; SIPH, siphunculus; SIPH_DW, distal width of siphunculus; Cauda_BW, basal width of cauda; URS, ultimate rostral segment; URS_BW, basal width of URS; MF, me- sosternal furca; FH, frontal horns; FH_BW, basal width of frontal horns; AP, anal plate; GP genital plate; GONA, gonapophyses. DNA sequencing Whole genomic DNA was extracted from a single individual preserved in 95% ethanol using the DNeasy Blood & Tissue Kit (Qiagen, Hilden, Germany). The standard DNA barcode gene of animals, cytochrome c oxidase subunit | (5' ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 37 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma region of COl) was amplified with primer LepF (5-ATTCAACCAATCATAAAGA- TATTGG-3') and LepR (5'-TAAACTTCTGGATGTCCAAAAAATCA-3’) (Foottit et al. 2008). PCR amplifications were performed in a final volume of 25 uL reaction mixture containing 2 uL of template DNA, 0.5 uL of both forward and reverse primer (10 uM), 0.25 uL of Tag DNA polymerase (5 U/uL), 17.25 pL of double distilled H20, 2.5 uL of 10 x buffer and 2 uL of dNTP. PCR thermal regime was as follows: 5 min of initial denaturation at 95 °C, 35 cycles of 20 s at 94 °C, 30s at 50 °C (the annealing temperature) and 2 min at 72 °C, and 10 min of final exten- sion at 72 °C. The products of PCR were visualized by electrophoresis on a 1% agarose gel and then bidirectionally sequenced at Beijing Tsingke Biotech Co., Ltd (Beijing, China). All sequences were assembled by ContigExpress (Vector NTI Suite 6.0, InforMax Inc.), and the reliability was checked by BLAST. The COI sequence was submitted to GenBank under the accession number PP910380. The phylogenetic analysis was performed based on the sequence of the new species and 15 COI sequences downloaded from NCBI: four sequences of C. tattakana tattakana, two unidentified Chaitoregma species sequences, and seven sequences representing seven species within the tribe Cerataphidini; two sequences representing two species within the tribe Nipponaphidini were used as outgroups (Table 2). Multiple alignment was conducted using MUSCLE (Edgar 2004). Maxi- mum-likelihood phylogenies were inferred using MEGA X (Tamura et al. 2021) under the GTR+G+l model for 500 bootstraps. The mean genetic distances among the Chaitoregma species were calculated using MEGA X (Tamura et al. 2021) under Kimura’ s two-parameter (K2P) model (Kimura 1980). Specimen deposition The holotype and paratypes of the new species examined here are deposited in the Insect Systematics & Diversity Lab, Fujian Agriculture and Forestry Univer- sity, Fuzhou, China. Table 2. Voucher information and GenBank accession numbers of aphid samples used in molecular data analysis. Species Astegopteryx bambusae Astegopteryx styracophila Ceratovacuna graminum Ceratovacuna lanigera Ceratovacuna keduensis Chaitoregma sp. Chaitoregma sp. Chaitoregma kirlia Chaitoregma tattakana tattakana Chaitoregma tattakana tattakana Chaitoregma tattakana tattakana Chaitoregma tattakana tattakana Metanipponaphis lithocarpicola Neohormaphis wuyiensis Pseudoregma panicola Pseudoregma bambucicola ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 Host Locality GenBank accession number References Bambusoideae spp. Fujian, China MH821551 Li et al. (2023) Zingiberaceae spp. Hainan, China JX489626 Chen et al. (2014) Bambusoideae spp. Fujian, China MH821618 Li et al. (2023) Bambusoideae spp. Fujian, China MH821646 Li et al. (2023) Bambusa ventricosa Fujian, China MH821625 Li et al. (2023) Bambusoideae spp. Fujian, China MH821702 Li et al. (2023) Bambusoideae spp. Fujian, China MH821703 Li et al. (2023) Bambusoideae spp. Fujian, China PP910380 This study Bambusoideae spp. Yunnan, China MH821704 Li et al. (2023) Bambusoideae spp. Yunnan, China MH821705 Li et al. (2023) Bambusoideae spp. Yunnan, China JX489629 Chen et al. (2014) Bambusoideae spp. Guizhou, China JN032707 Huang et al. (2012) Castanopsis spp. Fujian, China JX489637 Chen et al. (2014) Quercus spp. Fujian, China JX489762 Chen et al. (2014) Cyrtococcum patens Fujian, China MH820756 Li et al. (2023) Bambusoideae spp. Fujian, China MH820693 Li et al. (2023) 38 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma Taxonomy Genus Chaitoregma Hille Ris Lambers & Basu, 1966 Chaitoregma Hille Ris Lambers & Basu, 1966: 15; Eastop and Hille Ris Lambers 1976: 143; Ghosh et al. 1977: 102; Blackman and Eastop 1984: 258; Remau- diére and Remaudiére 1997: 182; Qiao and Zhang 2003: 146; Aoki and Kuro- su 2010: 2; Nieto Nafria et al. 2011: 171. Chaetoregma Tao, 1991: 41. (incorrect subsequent spelling). Generic diagnosis. In apterae, body round, flat, and strongly sclerotized. Head with 1 pair of frontal horns, cylindrical with broadly rounded tips, nymph with blunt frontal horns from birth. Head plus pronotum, meso- and metanotum, and abd. tergites | and VIII mutually free, the other abdominal tergites completely fused without sutures. Body dorsum with irregularly shaped wax facets, some- times wax plates appear in groups along the abdominal margin. Eyes with 3 facets. Antennae 4- or 5-segmented, with primary rhinaria on the terminal seg- ment. Rostrum short and thick. Ultimate rostral segment blunt, wedge-shaped, with 3 pairs of long primary setae. Legs normal, claws normal, first tarsal chae- totaxy: 4, 3, 2. Siphunculi pore-like, not situated on hairy cones. Cauda knobbed and constricted at base. Anal plate bilobed. Distribution. China (Fujian, Guangdong, Taiwan, Yunan), India (Darjeeling). Host plants. Various species of Bambusoideae. Type species. Oregma tattakana Takahashi, 1925 by original designation. Chaitoregma tattakana tattakana (Takahashi, 1925) Oregma tattakana Takahashi, 1925: 47; Takahashi 1931: 96; Tao and Tseng 1938: 218; Shinji 1941: 1115; Chu 1957: 144; Tao 1969: 57. Chaitoregma tattakana Hille Ris Lambers & Basu, 1966: 16; Eastop and Hille Ris Lambers 1976: 143, 327; Ghosh et al. 1977: 102; Blackman and Eastop 1984: 258; Fukatsu et al. 1994: 617; Remaudiére and Remaudiére 1997: 182; Stern et al. 1997: 84; Fang et al. 2006: 993; Aoki and Kurosu 2010: 22; Fang et al. 2011: 160. Chaetoregma tattakana Tao, 1991: 42. Specimens examined. «7 apterous viviparous females, CHINA: Yunnan (24.886°N, 102.839°E), 9 Nov. 2017, No. HL_zld20171109_2_A to G, coll. L. D. Zeng (FAFU). Chaitoregma kirlia sp. nov. https://zoobank.org/3EAB9F31-3213-4EEE-8DCF-1E0732092F78 Figs 1-3, Table 1 Etymology. The specific epithet “kirlia” is a noun in apposition, named after Kirlia, a character from the popular Pokémon series. They both have a pair of front horns. The name was chosen to honor the graceful and elegant nature of this new species, reminiscent of the character. ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 39 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma Figure 1. Chaitoregma kirlia, apterous viviparous female A dorsal view of body B head and pronotum C frontal horns D marginal wax gland plates on mesonotum E ultimate rostral segment F blunt frontal horns in embryo G mesoster- nal furca H antenna I spinal setae and wax facets on mesonotum and metanotum J wax facets on dorsal abdomen K setae on first fore tarsal joint L wax gland plates on marginal abdomen (A-E, G-K from HL_20160812_19_A; F from HL_20160812_19_C; L from HL_20160812_19_D). Scale bars: 0.5 mm (A); 0.05 mm (B-L). ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 40 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma Figure 2. A-E Chaitoregma kirlia, apterous viviparous female A siphunculi with 5 setae around B genital plate C abdominal tergites VIII D gonapophysis E cauda and anal plate F, G Chaitoregma tattakana apterous viviparous female F head and pronotum G dorsal view of body (A-E from HL_20160812_19_A, F-G from HL_zld20171109_2_C). Scale bars: 0.05 mm (A-G). ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 A Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma Figure 3. Chaitoregma. kirlia sp. nov., colony on the underside of leaf of one undefined bamboo species, attended by an ant species, Crematogaster sp. Description. Apterous viviparous female: body oval, dark purple in life. Body dorsum slightly covered with white wax powders, marginal areas on body with undeveloped flaky wax powders in life. For morphometric data see Table 1. Mounted specimens. Body oval and dark sclerotic (Fig. 1A), 1.62—1.82 x as long as its width, sclerotic areas evenly covered with numerous irregularly shaped wax facets, wax facets arranged radially at the intersegmental area (Fig. 1J). Head and pronotum fused (Fig. 1B), mesonotum, metanotum, abdom- inal segment | and VIII mutually free; abdominal segment II to VII completely fused, sutures not clearly distinct. Head. Frons with a pair of frontal horns, frontal horns cylindrical with broadly rounded tips, about 1.2-1.7 x as long as their basal width, smooth, with 6-12 short setae (Fig. 1C). Distance between the apex of the horns about 0.109- 0.125 mm. Embryo with blunt frontal horns (Fig. 1F). Antennae 4-segmented, sometimes 5-segmented, about 0.15—-0.19 x body length (Fig. 1H); length in pro- portion of segments I-IV: 25-37, 25-30, 64-73, 40-52, and 18-27. Antennal se- tae all fine, long with acute apices; segments I-V with 1-2, 2-3, 3-6, 1-2 setae, respectively; apical part of processus terminalis with 2-5 setae (Fig. 1F). Length of setae on segment III 0.02—0.045 mm. Segment III narrowed toward base, sen- sorium very small. Eyes with 3 facets in apterae. Rostrum short, reaching or near- ly reaching mid-coxae; URS wedge-shaped (Fig. 1E), about 0.60—-0.75 x of second joint of hind tarsi, with 3 pairs of long primary setae. Dorsal head and pronotum with 15-20 setae, 0.050-0.066 mm, fine wavy, with acute apices. Thorax. Margin of the pronotum to metanotum each with some wax facets (Fig. 1D). Dorsal setae on thorax similar to head setae. Pronotum with 2 pairs ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 42 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma of spinal setae and 2 pairs of marginal setae; mesonotum, and metanotum each with 2 pairs of spinal, 1-2 pair of pleural and 2 pairs of marginal setae, respectively. Mesosternal furca with 2 separated arms (Fig. 1G), each arm 1.53- 2.47 x as long as basal diameter of antenna segment III. Legs short, trochanters nearly fused with femora; hind tibia 0.22—0.26 x as long as body. Setae on legs fine and slightly long; setae on hind tibia 0.90-1.27 x as long as its diameter. First tarsal chaetotaxy: 4, 3, 2. The first fore tarsal joint of the legs with 2 long setae and 2 short setae (Fig. 1K), while the first hind tarsal joint with 2 long setae. Abdomen. Abdominal tergites I-VII each with 1 pair of wax gland plates on mar- ginal sclerites, composed with irregularly shaped to rounded wax gland facets (Fig. 1L), surrounding 1 marginal seta, wax gland facets composed with 2-5 facets. Ab- dominal tergites I-V each with 2 pair of spinal setae, 2—4 pair of pleural and 1 pair of marginal setae; tergites VI with 1 pair of spinal, 1 pair of pleural and 1 pair of mar- ginal setae; tergites VI with 1 pair of spinal and 1 pair of marginal setae; tergite VIII with 8-16 setae (Fig. 2C), setae on abdominal tergite VIII 2.9-3.7 x as long as bas- al diameter of antennal segment III. Spiracles round, open. Siphunculae pore-like, about 0.03 mm, slightly elevated, not situated on setaceous cones (Fig. 2A). Cauda knobbed and constricted at base, with about 3-7 setae (Fig. 2E). Anal plate bi- lobed, with 5-7 setae on each lobe (Fig. 2E). Genital plate with 4 anterior setae and 7-9 posterior setae (Fig. 2B). Gonapophyses two, each with 5-7 setae (Fig. 2D). Specimens examined. Holotype + 1 apterous viviparous female, CHINA: Fujian (Mount Wuyishan, 27.630°N, 117.394°E, alt. 234 m), 12 Aug. 2016, HL_20160812_19_A, coll. X. L. Huang and X. L. Lin (FAFU). Paratypes + 7 apter- ous viviparous females (HL_20160812_19_B to D on the same slide as holotype; HL_20160812_19_EtoGonanotherslide), withthe samecollectiondataas holotype. Other examined material. «3 apterous viviparous females on the same slide, CHINA: Guangdong (Mount Lianhuashan, 23.067°N, 115.241°E, Alt. 905 m), 16 July 2024, WYZ_20240716_6_A to D, coll. Y. Z. Wang (FAFU). Distribution. China: Fujian (Mount Wuyishan), Guangdong (Mount Lianhuashan). Host plants. One unknown species of Bambusoideae. Biology. According to our records, Chaitoregma kirlia forms large colonies on the undersides of leaves of the host plant, and can be attended by ants, Crematogaster sp. (Fig. 3). In the wild, it has been observed that in addition to the purple individuals of this new species within the colony, there are occasionally a few yellow individu- als; these are suspected to be mixed colonies with another Chaitoregma species, possibly C. tattakana suishana (Fig. 3). The entire life cycle is unknown. Taxonomic notes. The new species resembles the type species C. tattakana (Takahashi, 1925), they but differ as follows: C. kirlia sp. nov. has distinct wax gland plates on the margin of abd. I-VI (Fig. 1L), while other species in this genus do not have distinct wax gland plates (Qiao and Zhang 2003, Fig. 2G); The new species has a greater distance between the apex of the frontal horns (0.109- 0.135 mm) compared to C. tattakana tattakana (0.098-0.110 mm); length of the setae on the dorsum of head (0.050-0.066 mm), abd. tergites | (0.035-0.059 mm) and VIII (0.042-—0.072 mm) are significantly shorter than C. tattakana tat- takana (0.079-0.112 mm; 0.056—-0.113 mm; 0.062—0.096 mm); HT 0.22-0.26 x body length (C. tattakana tattakana: 0.25—0.30x), PT 0.4—0.68 x Ant.IV (C. tat- takana tattakana: 0.27-0.48x), URS 0.78-1.04 x URS_BW (C. tattakana tattakana: 1.16-1.43x), URS 0.60-0.75 x 2HT (C. tattakana tattakana: 0.54—0.58x). Number of setae on various body parts are also different (Table 1). ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 43 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma JX489629.1Chaitoregma tattakana = MH821705.1 Chaitoregma tattakana —@ JN032707.1 Chaitoregma tattakana MH821702.1 Chaitoregma sp. MH821703.1 Chaitoregma sp. PP910380 Chaitoregma kirlia Wang & Huang sp. nov. r——9 +MH821551.1 Astegopteryx bambusae © JX489626.1 Astegopteryx styracophila MH81 1646.1 Ceratovacuna lanigera MH820693.1 Pseudoregma bambucicola MH821625.1 Ceratovacuna keduensis MH821618.1 Ceratovacuna graminum © MH820756.1 Pseudoregma panicola © JX489637.1 Metanipponaphis lithocarpicola it ) JX489762.1 Neohormaphis wuyiensis r MH821704.1 Chaitoregma tattakana | Tree scale: 0.1 Figure 4. The maximum-likelihood phylogenetic tree of the samples based on COI sequences. Numbers beside main nodes are bootstrap support values (>50). Solid red circle marks the new species. Table 3. Mean genetic distances (K2P) among new species and some other species in Chaitoregma based on COl sequences. The percentage of genetic distances are shown in the lower left half of the matrix, and the percentage of standard errors are shown in the upper right half of the matrix. PP910380 MH821705.1 JX489629.1 JN032707.1 MH821702.1 C. kirlia C. tattakana C. tattakana C. tattakana Gap. tattakana tattakana tattakana PP910380 C. kirlia 1.20 1.20 1.18 12 MH821705.1 C. tattakana tattakana 7.40 0 0.56 0.73 JX489629.1 C. tattakana tattakana 7.40 0 0.56 0.73 JN032707.1 C. tattakana tattakana 7.19 1.82 ‘G2 0.76 MH821702.1 C. sp. 7.61 3.32 332 3.02 According to the original description, C. kirlia sp. nov. differs from C. ader- uensis at least by following: HT 0.26-0.30 mm (C. aderuensis: 0.37 mm); WA 0.18-0.21 mm (C. aderuensis: 0.23 mm). Molecular analyses The phylogenetic results illustrate the evolutionary relationships among some species within the tribe Cerataphidini, highlighting the new species marked in red. The sequences of C. kirlia and C. tattakana tattakana cluster into two dis- tinct clades, indicating clear genetic divergence between them (Fig. 4). Genetic distance threshold has been used as the basis for species classifi- cation, and in aphid groups, a generally applicable threshold range is from 2% to 2.5% (Liu ei al. 2013; Lee et al. 2017; Zhu et al. 2017; Li et al. 2019, 2023). The K2P distances between C. kirlia and other species was around 7.19-7.61% (Table 3). This significant genetic distance, exceeding the typical threshold range, supports C. kirlia as a distinct species. Discussion When the genus Chaitoregma was established by Hille Ris Lambers and Basu (1966), they redescribed C. tattakana tattakana only using the samples collected ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 AA Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma from southern Himalayas. There could be some subspecific differences between these samples, which could have led to inaccuracies in their redescription. On Blackman and Eastop’s website “Aphid on world’s plants” (Blackman and Eastop 2024), they mentioned that C. aderuensis was not clearly distinct from C. tattakana tattakana based solely on the original description. After examining the original description, we determined that the shape of the frontal horns is key in distinguishing them: the frontal horns of C. aderuensis are narrowed on the apical part, while the frontal horns of C. tattakana tattakana are broadly rounded at the apical part. This distinction is based solely on the original description, and we need more sampling in the future to confirm the relationship between these two species. According to the original description, the subspecies C. tattakana suishana can be distinguished from C. tattakana tattakana by its yellowish-brown body color in life, frontal horns not constricted at the base and slightly narrowed to- wards the apex, SIPH_DW longer, about 0.037 mm, and a slightly less sclerotic body (Takahashi 1929). These limited features indicate that C. tattakana suis- hana should likely be considered a distinct species rather than a subspecies. In the future, we need more sampling or the opportunity to examine type speci- mens to clarify the relationships between these species (subspecies). Key to species of Chaitoregma (Apterous viviparous females) 1 BOO VEIOW IMITORe cose hod At care teat meets C. tattakana suishana =. “BoOUWwhaZy-bUlS pul Dheahn Nes. Ss7teale | Seth ten Sie ass lee ce coast, 2 2 Abdominal tergites I-VII each with 1 pair of wax gland plates on marginal sclerites, composed of irregularly-shaped to rounded wax gland facets... Ex ce fenavig PEAK AA URNIN apy POBESAANNUAA eng OO CREASY ANCE LA ay sh'Ca cE sxE En Say EASON C. kirlia sp. nov. - Abdominal tergites I-VII only with roundish stippled wax facets, which are POC IMA FOULS An) Meet oArcrsst hy pea erwerecnn eseaitin Seecpeeey Rens Senvwbet Aamo teswn eens 3 3 Head narrowed between antenna, and horns narrowed on apical part....... ROU Pere SeeeD aria APPA AP en in PPR hada! em reg 9 OR aeRO A i rr C. aderuensis —- Horns not expanded at base, not narrowed toward apex, but sometimes very slightly narrowed toward base, broadly rounded at apical part........... Sistonaiteb ines cert aasametencnten ae intenten cad oil it Ban sremeeetrem ean Oma sans cede. C. tattakana tattakana Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Funding This research was supported by the Special Investigation Program for National Science and Technology Basic Resources (2022FY100500) and the Special Fund for Science and Technology Innovation of Fujian Agriculture and Forestry University (KFB23016). Author contributions Writing - original draft: YW. Writing - review and editing: XH. ZooKeys 1218: 35-47 (2024), DOI: 10.3897/zookeys.1218.133287 45 Yizhe Wang & Xiaolei Huang: Description of a new species of Chaitoregma Author ORCIDs Yizhe Wang ® hitps://orcid.org/0009-0004-4703-2226 Xiaolei Huang © https://orcid.org/0000-0002-6839-9922 Data availability All of the data that support the findings of this study are available in the main text. 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