Taxonomic Study of the Chalcidoid Wasps Sycoscapter Saunders (Hymenoptera: Pteromalidae) Associated with Monoecious Ficus in Taiwan, with Description of Four New Species

© 2024 Academia Sinica, Taiwan Open Access Taxonomic Study of the Chalcidoid Wasps Sycoscapter Saunders (Hymenoptera: Pteromalidae) Associated with Monoecious Ficus in Taiwan, with Description of Four New Species Po-An Chou1, Wen-Bin Yeh2, Zhi-Hui Su3, and Hsy-Yu Tzeng1,* 1Department of Forestry, National Chung Hsing University, No. 145 Xinda Rd., Taichung City 40227, Taiwan. *Correspondence: E-mail: [email protected] (Tzeng), Fax: +86 04 2287 3628 E-mail: [email protected] (Chou) 2Department of Entomology, National Chung Hsing University, No. 145 Xinda Rd., Taichung City 40227, Taiwan. E-mail: [email protected] (Yeh) 3JT Biohistory Research Hall, Takatsuki, Osaka 569-1125, Japan. E-mail: [email protected] (Su) urn:lsid:zoobank.org:pub:1F1AF040-147B-4A45-A475-C8F6EB263DE1 Received 2 February 2024 / Accepted 26 June 2024 / Published 25 December 2024 Communicated by Y. Miles Zhang As a prominent group of nonpollinating fig wasps widely distributed in the paleotropics, Sycoscapter Saunders has been subject to limited taxonomic attention. This study presents the first comprehensive taxonomic investigation of Sycoscapter wasps associated with five Taiwanese monoecious fig species, employing both molecular and morphological methods. Phylogenetic analyses using COI and COI+28S data revealed the presence of five species associated with monoecious figs in Taiwan and neighboring regions: Sycoscapter gajimaru (Ishii), Sycoscapter piceoscapus Chou & Tzeng sp. nov., Sycoscapter monticola Chou & Tzeng sp. nov., Sycoscapter ishiianus Chou & Tzeng sp. nov., and Sycoscapter littoralis Chou & Tzeng sp. nov. Morphologically, these five Sycoscapter species possessed distinctive characteristics, including the male head shape, which distinguished them from related species. Furthermore, males of all five species exhibited rudimentary wing vestiges, commonly found in wasps associated with monoecious figs but absent in those associated with dioecious figs. Overall, this study enriches our understanding of chalcidoid fauna in Taiwan and provides insight into the mechanisms that sustain intricate ecosystems. Key words: Fig wasp, Sycoryctinae, Sycoryctini, Rudimentary wing, Symbiosis BACKGROUND The obligate symbiosis between fig trees (Ficus L.) and chalcidoid wasps (Hymenoptera), especially Agaonidae and Pteromalidae, serves as a well-established model for exploring speciation and coevolution (Weiblen 2002; Borges 2015). In this context, the subtribe Sycoryctina (http://www.figweb. org; van Noort and Rasplus 2024) of Otitesellini in Pteromalidae is one of the most common groups interacting with figs and agaonid wasps in the paleotropics (Segar et al. 2012; Burks et al. 2022). Since female Sycoryctina wasps, as external exploiters, use their elongated ovipositors to extract resources from within figs for their offspring, the lengths of ovipositors must correspond to the fig-wall thicknesses (Tzeng et al. 2014). Consequently, they exhibit high host-specific speciation and contribute substantially to the tribe’s diversity (McLeish et al. 2010). The genus Sycoscapter Saunders, one of the most diverse group of Sycoryctina, comprises 23 described species from Africa and Asia (Bouček 1988; Citation: Chou PA, Yeh WB, Su ZH, Tzeng HY. 2024. Taxonomic study of the chalcidoid wasps Sycoscapter Saunders (Hymenoptera: Pteromalidae) associated with monoecious Ficus in Taiwan, with description of four new species. Zool Stud 63:34. doi:10.6620/ZS.2024.63-34. Zoological Studies 63:34 (2024) doi:10.6620/ZS.2024.63-34 1 © 2024 Academia Sinica, Taiwan Berg and Wiebes 1992; Segar et al. 2012). However, differentiating Sycoscapter from other genera within the same tribe has been complicated by changeable diagnostic characters. Consequently, Bouček (1988) suggested the concept of consolidating all genera into Sycoscapter s.l. to resolve this ambiguity in Sycoryctini. Nevertheless, advancements in morphological analyses and molecular phylogeny have brought about the possibility of establishing a natural taxonomic system for Sycoryctini (Berg and Wiebes 1992; Segar et al. 2012). Presently, the genera synonymized by Bouček (1988) are reinstated and the diagnostic criteria for Sycoscapter s.s. encompass the following: in females, the forewing features a “boot-like” stigma and robust hairs, with symmetric funicular segments; in males, mesonotum is fused with metanotum and propodeum, and the basitarsus of the hind leg remains unexpanded (Berg and Wiebes 1992; Segar et al. 2012; Pramanik and Dey 2019). As a vital component of fig-wasp symbiosis, including interactions involving Sycoscapter, fig trees are key elements of tropical and subtropical ecosystems, encompassing approximately 750 described species (Berg and Corner 2005). Depending on the flower types in figs, Ficus species can be categorized as monoecious or functionally dioecious, with approximately half of all species falling into each category (Berg and Corner 2005; Cruaud et al. 2012; Gardner et al. 2023). Monoecious figs possess protogynous female and male flowers in each fig. Consequently, female flowers develop galls when oviposited, whereas the remainder form seeds through pollen transferred by the wasps. In contrast, functional dioecious figs allocate female flowers to distinct figs, with female figs containing fertile female flowers and male figs possessing male and infertile female flowers, which only form galls. Agaonid wasps associated with functional dioecious figs can lay eggs in the infertile female flowers of male figs but facilitate pollination in female figs without leaving offspring (Weiblen 2002). The coexistence of all flower types in a monoecious fig creates mixed layers of developing seeds and galls, promoting diverse and complex fig-wasp communities (Kerdelhué and Rasplus 1996). Moreover, as an increasing number of studies report the involvement of cryptic species in shaping these intricate fig-wasp communities in monoecious figs (Cook and Bean 2006; Darwell and Cook 2017), the necessity for comprehensive taxonomic studies employing phylogenetic analyses and species delineation becomes evident, with the specific aim of elucidating the functioning of this intricate ecosystem. In recent decades, researches on Sycoscapter wasps have predominantly focused on ecological and evolutionary aspects (McLeish et al. 2010 2012; Sutton et al. 2016), with taxonomic studies remaining relatively scarce (Bouček 1988; Berg and Wiebes 1992; Pramanik and Dey 2019). In Taiwan, fig trees play an important ecological role in lowland vegetation, with some monoecious species being representative plants in urban environments (Chao et al. 2008; Walther et al. 2018). However, similar to the limited taxonomic research on symbiotic Sycoscapter wasps globally, only a few species have been documented in Taiwan, as noted by Chen et al. (1999). Therefore, using both morphological and phylogenetic approaches, the present study comprises a comprehensive taxonomic investigation of Sycoscapter wasps associated with Taiwanese monoecious fig species. The study aims to provide insight into the delimitation of cryptic species and enhance our understanding of the symbiotic relationship between figs and Sycoscapter wasps. MATERIALS AND METHODS Among the 28 Taiwanese Ficus taxa, 6 are monoecious species. These include Ficus nervosa Heyne ex Roth, Ficus pubinervis Bl., Ficus benjamina L. var. bracteata Corner, Ficus caulocarpa (Miq.) Miq., Ficus microcarpa L. f., and Ficus subpisocarpa Gagnep. Notably, the former two species belong to the subgenus Pharmacosycea, whereas the remaining four belong to the subgenus Spherosuke (Berg 2005 and Corner; Gardner et al. 2023). With the exception of F. pubinervis, which approaches its northern distribution boundary on Lanyu and Ludao islands, the other monoecious fig species exhibit broad distribution encompassing not only the whole of Taiwan but also extending to regions in South China and the Ryukyu islands of Japan (Table S1). Given their wide distribution, D-phase figs (those ready for wasp release) were collected from various locations in Taiwan. Additionally, samples of F. microcarpa from adjacent regions were included in this study. Upon collection, figs were placed in containers with fine mesh until wasps emerged. Subsequently, all wasps were preliminarily identified and preserved in 95% alcohol. In addition, related specimens were also examined from museums and institutes, including the following: Department of Entomology at National Chung Hsing University, Taichung, Taiwan (NCHU); Taiwan Agricultural Research Institute, Taichung, Taiwan (TARI); Institute for Agro-Environmental Sciences, Ibaraki, Japan (NARO); and the Chinese Academy of Sciences, China (CAS). For each population, one to five adult wasps were randomly selected, and genomic DNA was extracted from the whole body using the QuickExtract DNA page 2 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Extraction Kit (Epicentre Biotechnologies, Madison, WI). Tissue was ground in 50 μL of QuickExtract solution and incubated at 65°C for 15 min, followed by 98°C for 2 min. A mitochondrial DNA gene, COI, and a nuclear ribosomal DNA gene, 28S, were used for molecular analyses of Sycoscapter wasps. Besides, combined COI+28S molecular data are recognized as valuable and commonly used in fig-wasp studies (Lopez-Vaamonde et al. 2009; Azuma et al. 2010; Yang et al. 2014). Primer sets LCO1490/HCO2198 for COI and D2-3551F/D2—4068R for 28S were used to amplify the two respective genes. Polymerase chain reaction conditions for the primer sets followed those described by Cruaud et al. (2010) and Heraty et al. (2004). After amplification, products were sequenced from both ends using a Taq Dye Terminator Cycle Sequencing Kit and an ABI 377A sequencer. All sequences have been deposited in GenBank under the following accession numbers: PP111396—PP111462 for COI sequences and PP162908—PP162951 for 28S sequences. Additionally, COI sequences of related wasp species from GenBank were incorporated into this study, including three populations of Sycoscapter associated with F. benjamina L., F. microcarpa L. f. and F. nervosa B. Heyne ex Roth. Sequence alignment of COI was performed using the ClustalW algorithm in MEGA 11 (Tamura et al. 2021), and that of 28S was conducted on TurboFold Ⅱ web server (https://rna.urmc.rochester.edu/ RNAstructureWeb/Servers/TurboFold.html; Tan et al. 2017). Two fig wasp species, Walkerella kurandensis ex F. microcarpa (Pteromalidae: Otitesellini: Otitesellina) and Sycoryctes patellais ex Ficus variegata (Pteromalidae: Otitesellini: Sycoryctina), belonging to the same tribe as Sycoscapter (http://www.figweb.org; van Noort and Rasplus 2024) were chosen as outgroup species. Owing to the unavailability of 28S sequences for the related species in GenBank, we constructed 28S tree and COI+28S tree based on the sequences generated in this study. Nucleotide substitution models GTR+I+G and GTR+I were determined as the bestfitting models for the COI gene and the 28S gene, respectively, using PartitionFinder 2 (Lanfear et al. 2012). Phylogenetic analyses were conducted using the maximum likelihood (ML) method on the IQ-TREE web server (http://iqtree.cibiv.univie.ac.at/) employing 1,000 ultrafast bootstrap replications (Nguyen et al. 2015; Trifinopoulos et al. 2016; Hoang et al. 2018). Bayesian inference (BI) analyses were conducted using MrBayes 3.2.7 (Ronquist et al. 2012), running Markov chain Monte Carlo methods for fifty million generations with sampling every 100 generations. Convergence was determined using Tracer 1.7.2 (Rambaut et al. 2018) with a threshold of all ESS parameters >200, and the initial 10% of trees were discarded as the burn-in. To determine the species delimitation of these Sycoscapter wasps in Taiwan, pairwise nucleotide divergence with Kimura 2-parameter (K2P) distance of COI gene and PTP model were conducted with MEGA 11 (Tamura et al. 2021) and bPTP web server (https://species.h-its. org/) employing 100,000 MCMC generations (Zhang et al. 2013), respectively. Morphological measurements were performed using specimen and scanning electron microscopy (SEM) images captured with Keyence VHX and Hitachi S3400N microscopes, respectively. To prepare specimens for imaging, wasps were subjected to 1 min of agitation in an ultrasonic cleaner to remove pollen. Subsequently, specimens were serially dehydrated using ethanol and hexamethyldisilazane (Heraty and Hawks 1998) or critical point drying methods (Quoram E3100). Following dehydration, wasps were dissected and mounted on cards for specimen imaging or dissected and coated with gold using a Quorum SC7620 for SEM imaging. ImageJ software was used to perform measurements. The morphological terminology used in this study followed Bouček and Rasplus (1991) and Berg and Wiebes (1992). To assess the morphological relationship between Sycoscapter wasps associated with Taiwanese monoecious figs and similar described species, we followed the key provided by Priyadasarnan (2000) and Pramanik and Dey (2019), subsequently creating comparison tables. Abbreviations used in the taxonomic description include the following: L: length; W: width; H: height; POL: postocellar distance; and OOL: ocellocular distance. RESULTS Among the six monoecious fig tree species in Taiwan, F. pubinervis was notable for its absence of Sycoscapter wasps. Conversely, all other species exhibited a high prevalence and abundance of Sycoscapter wasps within their figs. In total, 81 COI sequences, including 14 from GenBank, with a length of 703 bp were aligned. Additionally, 46 specimens with 28S combined data, ranging from 630 to 631 bp in length, were included in the analysis. The COI phylogenetic tree revealed the presence of five clades, with each being supported by high values of both ML ultrafast bootstrap and BI posterior probability (Fig. 1). Contrastingly, the 28S phylogenetic tree showed only four clades, with wasps reared from figs of F. subpisocarpa and F. caulocarpa being combined into one clade (Fig. S1). Most clades in the COI tree exhibited a strong association with specific fig species, except for two cases involving F. microcarpa and F. page 3 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan benjamina, which shared Sycoscapter wasp species. This observation was also reflected in the COI+28S combined data, where five clades corresponding to Sycoscapter wasps associated with Taiwanese monoecious figs could be discerned (Fig. 2). Despite the distinct and well-supported separation of the Sycoscapter species in Taiwanese monoecious figs, incongruence in tree topology was observed between the tree constructed using the COI gene and that constructed using COI+28S data. For example, in the COI tree, Clade Ⅱ appeared as a sister lineage to the group consisting of Clade Ⅲ-Ⅴ, then diverged from Clade I. In contrast, the tree based on COI+28S combined data grouped Clade Ⅱ with Clade Ⅲ. This incongruence was further supported by the relatively low values of both ML ultrafast bootstrap and BI posterior probability (Figs. 1 and 2). In addition to the genetic distances of 6.69–9.95% Fig. 1. Phylogenetic tree of the Sycoscapter species associated with monoecious figs in Taiwan and other congeners based on COI genes. The values at the nodes are the ultrafast bootstraps and posterior possibilities for maximum likelihood (ML) and Bayesian inference (BI) analyses, respectively. The number of each clade indicates the support value of the bPTP model. page 4 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan among species and 0.57–0.72% within species (Table 1), support values of the bPTP model (0.693–0.902) further supported the notion that the Sycoscapter wasps in this study represent five distinct species (Fig.1). Therefore, based on genetic differentiation and the topology of the phylogenetic tree reconstructed using COI+28S combined data, it is evident that five Sycoscapter species, corresponding to five clades, associated with monoecious figs exist in Taiwan, namely Sycoscapter gajimaru (Ishii), Sycoscapter piceoscapus Chou et Tzeng sp. nov., Sycoscapter monticola Chou et Tzeng sp. nov., Sycoscapter ishiianus Chou et Tzeng sp. nov., Fig. 2. Phylogenetic tree of the Sycoscapter species associated with monoecious figs in Taiwan based on COI+28S combined data. The values at the nodes are the ultrafast bootstraps and posterior possibilities for maximum likelihood (ML) and Bayesian inference (BI) analyses, respectively. Table 1. Percentage of pairwise nucleotide divergences with Kimura 2-parameter (K2P) distances and number of base pair differences based on the COI gene within and between species of Sycoscapter wasps associated with monoecious figs in Taiwan. In the inter-species column, the lower-left values are K2P distances and upper-right are bp differences Intra-species Inter-species Nucleotide divergence Base pair difference S. gajimaru S. piceoscapus S. monticola S. ishiianus S. littoralis S. gajimaru 4 0.57 49 47 63 53 S. piceoscapus 5 0.72 7.32 48 52 50 S. monticola 4 0.57 7.01 7.16 53 45 S. ishiianus 4 0.57 9.55 7.79 7.95 43 S. littoralis 4 0.57 7.96 7.48 6.69 6.39 page 5 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan and Sycoscapter littoralis Chou et Tzeng sp. nov. In terms of morphological observation, each species could be readily identified as a member of Sycoscapter by specific characteristics, such as symmetric funicles and a “boot-like” stigma on the forewing in females, and two terga in dorsal view and a non-enlarged basitarsus on the hind legs in males. Comparative analyses with other related Sycoscapter species revealed that Taiwanese species could be categorized into four morpho-groups based on similarities in male head-shape morphology. Sycoscapter gajimaru, for instance, clustered with Sycoscapter stabilis (Walker) and Sycoscapter benghalensis Pramanik and Dey owing to similarities in male head shape (rectangular with curved lateral margins). However, these species still differed based on other characters, such as vertex shape, setae number on female forewings, and malar L/eye L ratio in males (Table 2). As shown in table 3, S. piceoscapus and S. benghalensis Pramanik and Dey formed a morphogroup owing to shared characteristics, such as ovate head shape and large compound eyes in males, although they could be differentiated based on female characters, including vertex shape and scape coloration. Sycoscapter monticola exhibited a unique subhexagonal head shape in males, setting it apart from Sycoscapter vijayaii Priyadarsanan, although both share the same host fig species. Moreover, there were distinguishing features in male antennal segments (Table 4). The last group encompassed three species, namely S. ishiianus, S. infectorius (Joseph), and S. littoralis, which exhibited a long rectangular head shape with straight lateral margins. However, they could be distinguished through various characters, including head shape, maxillary palp segment in females, and the spur on the fore tibia in males (Table 5). Table 3. Comparison of morphological characters between Sycoscapter picescapus sp. nov. and S. benjaminae Pramanik and Dey S. piceoscapus S. benjaminae Female POL/ OOL 7.07 6 Vertex concave straight Scape coloration black yellow Sculpture on antennal scrobes reticulate psilate Seta on forewing 7–10 in 2 rows 11 in 4 rows Marginal vein L/ stigmal vein L 2.3 1.7 Ovipositor L/ metasoma L 4.75 4.6 Male Wing vestigial L/ mesosoma L 1.39 1.7 Characters of S. benjaminae referred to Pramanik and Dey (2019). Table 2. Comparison of morphological characters between Sycoscapter gajimru (Ishii), S. stabilis (Walker) and S. benghalensis Pramanik and Dey S. gajimaru S. stabilis S. benghalensis Female POL/ OOL 8.05 ≥ 9 9 Vertex concave straight straight Head H/ head W 0.79 0.83 1.3 Seta on forewing 5–7 in 2 rows 10 in 1 row 23 in 4 rows Marginal vein L/ stigmal vein L 3 1.7 1.7 Ovipositor L/ metasoma L 4.03 5.3 4.7 Male Head L/ head W 1.18 0.85-1.21 1 Malar L/ eye L 1.79 1.52 1 Mandible L/ mandible W 2.3 1.7 2.7 Characters of S. stabilis referred to Pramanik and Dey (2019) and Wiebes (1967) and that of S. benghalensis referred to Pramanik and Dey (2019). page 6 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan In addition to head shape in males, the presence or absence of rudimentary wing vestiges in males could also be used to categorize Sycoscapter wasps into two morpho-groups. Notably, wasps possessing rudimentary wing vestiges were exclusively associated with monoecious figs, whereas those lacking vestiges were associated with functional dioecious figs. TAXONOMY Family Pteromalidae Dalman, 1820 Genus Sycoscapter Saunders, 1883 Sycoscapter gajimaru (Ishii, 1934) (Figs. 3, 4, 5) Goniogaster gajimaru Ishii, 1934: 89, pls. 2(20). Sycoscapter gajimaru Wiebes, 1964: 83 (Japan); Yokoyama and Iwatsuki, 1998: 43 (Japan); Chen et al. 1999: 73, fig. 19 (Taiwan); Karube et al. 2022: 51, fig. 43 (Kita-Iwo, Japan; introduced). Type locality: Naha, Okinawa, Japan. Material examined: Lectotype: 1♀, Naha, Okinawa, 22-Ⅲ-1934, Col. T. Ishii (NARO), designated here. Others: Japan: 1♀1♂, Naha (26.226520, 127.713802), Okinawa, ex Ficus microcarpa L. f., 3-Ⅵ-2023, leg. P. A. Chou (NCHU); 1♀, Amami (28.391214, 129.506937), Kagoshima, ex Ficus microcarpa L. f., 9-Ⅴ-2021, leg. K. Arimoto (NCHU); 1♀, Minamidaito (25.836189, 131.237121), Okinawa, ex Ficus microcarpa L. f., 20-Ⅴ-2022, leg. K. Arimoto (NCHU). Taiwan: 1♂1♀, Fugui Cape (25.292583, 121.538262), New Taipei City, ex Ficus microcarpa L. f., 13-Ⅸ-2020, leg. P. A. Chou (NCHU); 1♀, National Taiwan University, Taipei City, ex Ficus microcarpa L. f., 6-Ⅸ-1991, leg. C. F. Hsu (TARI); 1♀, Taichung Park, Taichung City, ex Ficus microcarpa L. f., 15-Ⅸ1991, leg. K. S. Lin (TARI); 1♀, Wanfeng, Taichung City, ex Ficus microcarpa L. f., 8-Ⅹ-1991, leg. K. S. Lin (TARI); 1♂1♀, Botanical Garden of National Museum of Natural Science (24.158742, 120.667746), Taichung Table 5. Comparison of morphological characters between Sycoscapter ishiianus sp. nov., S. infectorius (Joseph) and S. littoralis sp. nov. S. ishiianus S. infectorius S. littoralis Female POL/ OOL 5.59 6.7 5.35 Maxillary palp 4 3 4 Head shape obcordate obcordate rounded Seta on forewing 9–13 in 3 rows 15 in 3 rows 9–10 in 3 rows Marginal vein L/ stigmal vein L 2.6 unknown 2.6 Ovipositor L/ metasoma L 4.37 5.6 3.76 Male Pronotum shape subpentagonal unknown oblong Fore spur exceeds last tarsomere no yes no Characters of S. infectorius referred to Joseph (1953 1961) and Pramanik and Dey (2019). Table 4. Comparison of morphological characters between Sycoscapter monticola sp. nov. and S. vijayaii Priyadarsanan S. monticola S. vijayaii Female POL/ OOL 4.84 11 Seta on forewing 4–11 in 2 rows 7–10 in 1 row Marginal vein L/ stigmal vein L 2 1.5 Ovipositor L/ metasoma L 6.08 7 Male Head shape subhexagonal rectangular Claval segment 3 2 Characters of S. vijayaii referred to Priyadarsanan (2000) and Pramanik and Dey (2019). page 7 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan City, ex Ficus benjamina L. var. bracteata Corner, 27Ⅳ-2023, leg. P. A. Chou (NCHU); 1♀, Yuanlin Park, Changhua, ex Ficus microcarpa L. f., 13-Ⅸ-1991, leg. K. S. Lin (TARI); 1♀, Tsaotun, Nantou, ex Ficus microcarpa L. f., 8-Ⅹ-1991, leg. K. S. Lin (TARI); 1♀, Kenting Forest Recreation Area (21.961888, 120.814306), Pingtung, ex Ficus microcarpa L. f., 11Ⅷ-2022, leg. P. A. Chou (NCHU); 1♂1♀, Kenting Forest Recreation Area (21.964254, 120810716), Pingtung, ex Ficus benjamina L. var. bracteata Corner, 11-Ⅷ-2022, leg. P. A. Chou (NCHU); 1♀, Tali, Ilan, ex Ficus microcarpa L. f., 14-Ⅸ-1991, leg. T. F. Hsu (TARI); 1♂1♀, Shitiping (23.491086, 121.508953), Hualien, ex Ficus microcarpa L. f., 29-Ⅷ-2018, leg. P. A. Chou (NCHU); 1♂1♀, Taitung Seashore Park (22.751414, 121.610591), Taitung, ex Ficus microcarpa L. f., 25-Ⅲ-2023, leg. P. A. Chou (NCHU); 1♂1♀, Ludao (22.671815, 121.505912), Taitung, ex Ficus microcarpa L. f., 30-Ⅷ-2018, leg. P. A. Chou (NCHU). Description: Female: Whole L = 3.82–4.93 mm with body L = 1.08–1.43 mm and ovipositor sheath L = 2.74–3.50 mm. Body metallic green (Fig. 3C). Compound eyes pale red (Fig. 3A). Antenna scape and pedicel yellow, anelli, funicle and clava black (Fig. 3I). Legs yellow (Fig. 3J, 3L, 3N) except for the basal part of hind coxa black in antiaxial view (Fig. 3N). Head: Obcordate in front view (Fig. 3A); H = 0.26 mm, W over compound eyes = 0.32 mm, W between compound eyes = 0.22 mm. Compound eye H 1.5× malar space L, and 3× compound eyes W. POL 7.49× OOL. Clypeus margin with a thin projection in the middle (Fig. 4A). Face and antennal scrobes with raised reticulation (Fig. 3A). Mandible bidentate (Fig. 3G). Maxillary palp 3-segmented; length ratio = 3:4:4 (Fig. 4B). Labial palp 2-segmented; length ratio = 3:2 (Fig. 4B). The distance between toruli 0.3× clypeus margin. Antennal formula 11253 and L = 0.49 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:4:1:20:10 (Fig. 3I). Scape L 3.85× W, with sparse trichoid sensillae (Fig. 4C). Pedicel L 1.3× W, with sparse trichoid sensillae (Fig. 4C). Both anelli equal in length and the second one wider (Fig. 4C). All funicular segments equal in length; the first funicular segment L 0.92× W, with 3 multiporous placoid sensillae and 8 chaetica sensillae in antiaxial view; the chaetica sensilla longer than funicular segment (Fig. 4C). Claval segments slightly wider than funicular segments; the first claval segment L 0.76× W, with 3 multiporous placoid sensillae and 7 chaetica sensillae in antiaxial view. Mesosoma: Mesosoma L = 0.41 mm, W = 0.29 mm; length ratio of pronotum, scutum, scutellum and propodeum = 2:4:5:1. Pronotum, scutum and scutellum with raised reticulation but propodeum psilate (Fig. 3B) Pronotum with collar in ventral view. Scutum with incomplete notauli (Fig. 3B). Scutellum nearly as wide as long; punctures of reticulation rounded (Fig. 4D). Metanotum strongly compressed and the middle covered by scutellum. Propodeum transverse with two longitudinal keels. Forewing L = 1.01 mm, W = 0.44 mm, with 5–7 setae below the marginal vein; length ratio of submarginal vein, marginal vein, postmarginal vein and stigmal vein = 5:3:4:2 (Fig. 3P). Hind wing L = 0.58 mm, W = 0.12 mm; length ratio of submarginal vein and marginal vein = 2:3. Foreleg L = 0.65 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:2:5:4:3 (Fig. 3J). Fore tibia with a curve, bidentate spur reaching the apex of first tarsomere; 1 spine beside spur in both axial and antiaxial views (Fig. 4E, 4F). Fore tarsus 5-segmented; length ratio of each segment = 4:3:3:2:7. Mid leg L = 0.67 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 1:1:3:4:3 (Fig. 3L). Mid tibia with a straight spur; spur L 0.5× the first tarsomere L; 1 spine beside spur in axial view but no spine in antiaxial view (Fig. 4G, 4H). Mid tarsus 5-segmented; length ratio of each segment = 7:4:3:2:4. Hind leg L = 0.92 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:4:5:3 (Fig. 3N). Hind tibia with a straight spur; spur L 0.5× the first tarsomere L; 19-24 teeth in axial view and 3 spines beside spur in antiaxial view (Fig. 4I, 4J). Hind tarsus 5-segmented; length ratio of each segment = 8:4:3:2:5. Metasoma: Abdomen without ovipositor sheath L = 0.74 mm. Male: L = 1.33–1.40 mm. Body brown (Fig. 3D). Eyes black (Fig. 3E). Mandible dark brown (Fig. 3H). Antenna pale yellow (Fig. 3E). Legs brown (Fig. 3K, 3M, 3O). Head: Rectangular shape in dorsal view (Fig. 3E); L without mandible = 0.45 mm, W = 0.38 mm. Mandible L = 0.25 mm, W = 0.10 mm. Mandible falcate with a fine tooth in the middle (Fig 3H). Clypeus margin concave in the middle. Maxillary palp 4-segmented; length ratio = 3:3:1:3 (Fig. 5B). Labial palp 2-segmented; length ratio = 3:2 (Fig. 5B). Compound eye L 2.5× W. Malar space L 1.79× compound eye L. Toruli close to clypeus margin. Antennal formula 11153 and L = 0.37 mm; length ratio of scape, pedicel, anellus, funicle and clava = 11:7:1:8:7. Scape L 2.51× W, with sparse trichoid sensillae (Fig. 5A). Pedicel L 3.32× W, with sparse trichoid sensillae (Fig. 5A). The first and third funicular segment swollen, L 0.6× W; other funicular segments L 0.55× W; all funicular segments with trichoid sensillae (Fig. 5A). Claval segments as wide as the swollen funicular segments; the first claval segment L 0.9× W, with trichoid sensillae and multiporus placoid sensillae (Fig. 5A). Mesosoma: Long pentagon in dorsal view (Fig. page 8 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Fig. 3. Sycoscapter gajimaru (Ishii, 1934). A, Female head, front; B, Female mesosoma, dorsal; C, Female habitus, lateral; D, Male habitus, lateral; E, Male head, dorsal; F, Male mesosoma, dorsal; G, Female left mandible, ventral; H, Male left mandible, dorsal; I, Female antenna; J, Female right foreleg; K, Male right foreleg; L, Female right mid leg; M, Male right mid leg; N, Female right hind leg; O, Male right hind leg; P, Female forewing. Scale bar = 0.1 mm if no number is noted. page 9 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Fig. 8. Scanning electron images of male Sycoscapter piceoscapus sp. nov. A, Antenna; B, Maxillary palps and labial palps; C, Left fore tibia, axial; D, Right tibia, antiaxial; E, Left mid tibia, axial; F, Right mid tibia, antiaxial; G, Right hind tibia, axial; H, Left hind tibia, antiaxial. Scale bar = 0.03 mm. page 16 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Hind leg L = 0.96 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 4:1:3:3:2 (Fig. 6O). Hind tibia with a straight spur reaching the third tarsomere; 15–17 spines in axial view and 23–25 spines in antiaxial view (Fig. 8G, 8H). Hind tarsus 5-segmented, length ratio of each segment = 1:1:1:1:4. Metasoma: Abdomen L = 0.44 mm. Host: Ficus microcarpa L. f. and Ficus benjamina L. Distubution: Taiwan: Hsinchu, Taichung, Changhua, Kinmen; China: Guangdong, Hainan. Etymology: This species is named after the dark coloration of the scape in females. Diagnosis: This species is similar to S. benjaminae Pramanik and Dey but can be distinguished by the characters in female including vertex shape (concave in S. piceoscapus vs. straight in S. benjaminae), scape coloration (black in S. piceoscapus vs. yellow in S. benjaminae), sculpture on antennal scrobe (reticulate in S. piceoscapus vs. psilate in S. benjaminae); in male including the ratio of rudimentary wing vestige L to mesosoma L (1.39 in S. piceoscapus vs. 1.7 in S. benjaminae). Remarks: This species has the same hosts as S. gajimaru, and may co-occur in the same tree with S. gajimaru. Sycoscapter monticola Chou & Tzeng sp. nov. (Figs. 9, 10, 11) urn:lsid:zoobank.org:act:5FC6CCEC-2A06-458A-956BD4639EB3CB75 Type locality: Zhiben Forest Road, Taitung, Taiwan. Material examined: Holotype: 1♀, Zhiben Forest Road (22.783507, 120.015736), Taitung, ex Ficus nervosa Heyne ex Roth., 10-Ⅴ-2021, leg. P. A. Chou (NCHU). Paratypes: 1♂, Zhiben Forest Road (22.783507, 120.015736), Taitung, ex Ficus nervosa Heyne ex Roth., 10-Ⅴ-2021, leg. P. A. Chou (NCHU); 1♂1♀, Qidu (25.122708, 121.662235), Keelung, ex Ficus nervosa Heyne ex Roth., 19-Ⅸ-2022, leg. P. A. Chou (TARI). Others: Taiwan: 1♂1♀, Urai (24.856259, 121.553437), New Taipei City, ex Ficus nervosa Heyne ex Roth., 11-ⅩⅡ-2019, leg. P. A. Chou (NCHU); 1♂1♀, Nan’ao (24.457640, 121.813020), Yilan, ex Ficus nervosa Heyne ex Roth., 26-Ⅲ-2023, leg. P. A. Chou (NCHU). China: 5♀, Bawangling (19.099, 109.176), Hainan Prov., ex Ficus nervosa Heyne ex Roth., 11-Ⅳ-2007, col. G. Feng, W. Li, H. Y. Hu, L. M. Niu (CAS) (examined from online photographs). Description: Female: Whole L = 5.23–5.54 mm with body L = 1.40–1.42 mm and ovipositor sheath L = 3.83–4.12 mm. Body metallic green (Fig. 9C). Compound eyes pale red (Fig. 9A). Antenna black except for the basal part of scape yellow (Fig. 9I). Legs yellow (Fig. 9J, 9L, 9N) except for the basal part of hind coxa black in antiaxial view (Fig. 9N). Head: Obcordate in front view (Fig. 9A); H = 0.27 mm; W over compound eyes = 0.34 mm; W between compound eyes = 0.23 mm. Compound eye H 1.24× malar space L, and 2.98× compound eyes W. POL 4.84× OOL. Clypeus margin with a blunt projection in the middle (Fig. 10A). Face with raised reticulation but antennal scrobes psilate (Fig. 9A). Mandible bidentate (Fig. 9G). Maxillary palp 3-segmented, length ratio of others = 2:2:5 (Fig. 10B). Labial palp 2-segmented, length ratio = 3:2 (Fig. 10B). The distance between toruli 0.18× clypeus margin. Antennal formula 11253 and L = 0.50 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:4:1:20:10 (Fig. 9I). Scape L 4.43× W, with sparse trichoid sensillae (Fig. 10C). Pedicel L 1.55× W, with sparse trichoid sensillae (Fig. 10C). Both anelli equal in length and the second one wider (Fig. 10C). All funicular segments equal in length; the first funicular segment L 1.09× W, with 3 multiporous placoid sensillae and 5 chaetica sensillae in antiaxial view; the chaetica sensilla longer than the funicular segment (Fig. 10C). Claval segments W almost equal to funicular segments, the first claval segment L 0.87× W, with 3 multiporous placoid sensillae and 5 chaetica sensillae in antiaxial view. Mesosoma: Mesosoma L = 0.47 mm, W = 0.31 mm; length ratio of pronotum, scutum, scutellum and propodeum = 2:3:4:1. Pronotum, scutum and scutellum with raised reticulation but propodeum psilate in dorsal view (Fig. 9B) Pronotum with collar in ventral view. Scutum with incomplete notauli (Fig. 9B). Scutellum nearly as wide as long, punctures of reticulation lengthened longitudinally (Fig. 10D). Metanotum strongly compressed and the middle covered by scutellum. Propodeum with two longitudinal keels. Forewing L = 1.09 mm, W = 0.51 mm, with 4-11 setae below the marginal vein; length ratio of submarginal vein, marginal vein, postmarginal vein and stigmal vein = 5:3:4:2 (Fig. 9P). Hind wing L = 0.70 mm, W = 0.18 mm; length ratio of submarginal vein and marginal vein = 2:3. Foreleg L = 0.76 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:2:5:4:3 (Fig. 9J). Fore tibia with a curve, bidentate spur reaching the apex of first tarsomere; 2-3 spines beside spur in axial view and 1 spine in antiaxial views (Fig. 10E, 10F). Fore tarsus 5-segmented, length ratio of each segment = 4:3:3:2:7. Mid leg L = 0.80 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 1:1:3:4:3 (Fig. 9L). Mid tibia with a straight spur; spur L 0.5× the first tarsomere L; 1 spine beside spur in axial view and 1 page 17 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan spine in antiaxial view (Fig. 10G, 10H). Mid tarsus 5-segmented, length ratio of each segment = 6:4:3:2:5. Hind leg L = 1.05 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:4:5:3 (Fig. 9N). Hind tibia with a straight spur; spur L 0.5× the first tarsomere L; 23-30 teeth in axial view and 2 spines beside spur in antiaxial view (Fig. 10I, 10J). Hind tarsus 5-segmented, length ratio of each segment = 9:4:3:2:5. Metasoma: Abdomen without ovipositor sheath L = 0.63 mm. Male: L = 1.57–1.70 mm. Body brown (Fig. 9D). Eyes black (Fig. 9E). Mandible dark brown (Fig. 9H). Antenna pale yellow (Fig. 9E). Legs brown (Fig. 9K, 9M, 9O). Head: Subhexagonal in dorsal view (Fig. 9E). L without mandible = 0.50 mm; W = 0.60 mm. Mandible L = 0.31 mm, W = 0.15 mm. Mandible falcate with a fine tooth at the middle (Fig 9H). Clypeus margin concave in the middle. Maxillary palp 4-segmented, length ratio = 2:2:1:2 (Fig. 11B). Labial palp 2-segmented, length ratio= 3:1 (Fig 11B). Compound eye L 3× W. Malar space L 1.14× compound eye L. Toruli close to clypeus margin, with a ridge in the middle. Antennal formula 11153 and L = 0.39 mm; length ratio of scape, pedicel, anellus, funicle and clava = 11:7:1:8:7. Scape L 4.45× W, with sparse trichoid sensillae (Fig. 11A). Pedicel L 3.89× W, with sparse trichoid sensillae (Fig. 11A). The first and third funicular segments swollen, L 0.63× W; all funicular segments with trichoid sensillae (Fig. 11A). Claval segments as wide as the swollen segments; the first claval segment L 0.71× W, with trichoid sensillae and multiporus placoid sensillae (Fig. 11A). Mesosoma: Oblong in dorsal view (Fig. 9F); L = 0.63 mm, W = 0.45 mm; length ratio of pronotum and the fused tergum = 3:2. Pronotum with collar in ventral view. Mesonotum, metanotum and propodeum fused in dorsal view (Fig. 9F). Rudimentary wing vestige present, L = 0.44 mm (Fig. 9F). Foreleg L = 0.92 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:2:2:2 (Fig. 9K). Fore tibia with a slightly curve, bidentate spur reaching the last tarsomere; 6 spines in axial view and 13–14 spines in antiaxial view (Fig. 11C, 11D). Fore tarsus 5-segmented, length ratio of each segment = 2:1:1:2:12. Mid leg L = 0.82 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 2:1:2:2:2 (Fig. 9M). Mid tibia with a straight spur reaching the second tarsomere; 14–15 spines in axial view and 13–16 spines in antiaxial view (Fig. 11E, 11F). Mid tarsus 5-segmented, length ratio of each segment = 2:1:1:1:6. Hind leg L = 1.17 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 7:2:5:6:4 (Fig. 9O). Hind tibia with a straight spur reaching the third tarsomere; 18–20 spines in axial view and 23 spines in antiaxial view (Fig. 11G, 11H). Hind tarsus 5-segmented, length ratio of each segment = 1:1:1:1:6. Metasoma: Abdomen L = 0.67 mm. Host: Ficus nervosa Heyne ex Roth. Distubution: Taiwan: Keelung, New Taipei, Yilan, Taitung; China: Hainan. Etymology: This species is named after the mountain habitat of its host fig tree. Diagnosis: This species has a subhexagonal head shape in males that shows no similarity with any other described species. Remarks: This species utilizes shares the same host species with an Indian congener, S. vijayaii Priyadasanan, but the two species can be distinguished by the characters in female including the ratio of POL to OOL (4.84 in S. monticola vs. 11 in S. vijayaii), the ratio of ovipositor L to metasoma L (6.08 in S. monticola vs. 7 in S. vujayaii); in male including the head shape (subhexagonal in S. monticola vs. rectangular in S. vijayaii), the claval segments (3 in S. monticola vs. 2 in S. vijayaii). Sycoscapter ishiianus Chou & Tzeng sp. nov. (Figs. 12, 13, 14) urn:lsid:zoobank.org:act:E98F9E4A-0B39-4683-84D526F485590FFD Type locality: South Dist., Taichung, Taiwan. Material examined: Holotype: 1♀, South Dist. (24.128055, 120.678623), Taichung City, ex Ficus subpisocarpa Gagnep., 31-Ⅶ-2023, leg. P. A. Chou (NCHU). Paratypes: 1♂, South Dist. (24.128055, 120.678623), Taichung City, ex Ficus subpisocarpa Gagnep., 31-Ⅶ-2023, leg. P. A. Chou (NCHU); 1♂1♀, Shuangliu (22.217694, 120.803907), Pingtung, ex Ficus subpisocarpa Gagnep., 8-Ⅱ-2021, leg. C. Y. Huang (TARI). Others: Taiwan: 1♂1♀, Lover’s Lake Park (25.156796, 121.705576), Keelung, ex Ficus subpisocarpa Gagnep., 24-ⅩⅠ-2020, leg. P. A. Chou (NCHU); 1♂1♀, Tianmu (25.118908, 121.532423), Taipei City, ex Ficus subpisocarpa Gagnep., 19-Ⅵ2022, leg. Y. R. Fang (NCHU); 1♂1♀, Shen’ao (25.127480, 121.816726), New Taipei City, ex Ficus subpisocarpa Gagnep., 19-Ⅷ-2022, leg. P. A. Chou (NCHU); 1♂1♀, Anping (22.995227, 120.164240), Tainan, ex Ficus subpisocarpa Gagnep., 2-Ⅸ2018, leg. P. A. Chou (NCHU); 1♂1♀, Frog Rock Trail (21.942526, 120.799618), Pingtung, ex Ficus subpisocarpa Gagnep., 24-ⅩⅠ-2020, leg. P. A. Chou (NCHU); 1♂1♀, Carp Mountain Park (22.753445, 121.144535), Taitung, ex Ficus subpisocarpa Gagnep., 2-Ⅸ-2022, leg. P. A. Chou (NCHU); 1♂1♀, Penghu Visitor Center (23.557232, 119.608105), Penghu, ex Ficus subpisocarpa Gagnep., 3-Ⅵ-2019, leg. P. A. Chou (NCHU); 1♂1♀, Kinhu Junior High page 18 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Fig. 9. Sycoscapter monticola sp. nov. A, Female head, front; B, Female mesosoma, dorsal; C, Female habitus, lateral; D, Male habitus, lateral; E, Male head, dorsal; F, Male mesosoma, dorsal; G, Female left mandible, ventral; H, Male left mandible, dorsal; I, Female antenna; J, Female right foreleg; K, Male right foreleg; L, Female right mid leg; M, Male right mid leg; N, Female right hind leg; O, Male right hind leg; P, Female forewing. Scale bar = 0.1 mm if no number is noted. page 19 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Fig. 10. Scanning electron images of female Sycoscapter monticola sp. nov. A, Toruli and epistomal margin; B, Maxillary palps and labial palps; C, Anelli and the first funiculus; D, Scutellum; E, Left fore tibia, axial; F, Right tibia, antiaxial; G, Left mid tibia, axial; H, Right mid tibia, antiaxial; I, Right hind tibia, axial; J, Left hind tibia, antiaxial. Scale bar = 0.03 mm. page 20 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Fig. 11. Scanning electron images of male Sycoscapter monticola sp. nov. A, Antenna; B, Maxillary palps and labial palps; C, Left fore tibia, axial; D, Right tibia, antiaxial; E, Left mid tibia, axial; F, Right mid tibia, antiaxial; G, Right hind tibia, axial; H, Left hind tibia, antiaxial. Scale bar = 0.03 mm. page 21 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan School (24.437888, 118.420643), Kinmen, ex Ficus subpisocarpa Gagnep., 23-Ⅹ-2021, leg. P. A. Chou (NCHU); Japan: 1♂1♀, Iriomote (24.384750, 123.893395), Okinawa, ex Ficus subpisocarpa Gagnep., 8-Ⅶ-2018, leg. P. A. Chou (NCHU). Description: Female: Whole L = 4.43–4.65 mm with body L = 1.22–1.24 mm and ovipositor sheath L = 3.19–3.41 mm. Body metallic green (Fig. 12C). Compound eyes pale red (Fig. 12A). Antenna black except for the yellow basal part of the scape (Fig. 12I). Legs yellow (Fig. 12J, 12L, 12N); basal part of hind coxa and middle of hind femur black in antiaxial view (Fig. 12N). Head: Obcordate in front view (Fig. 12A). H = 0.26 mm, W over compound eyes = 0.37 mm; W between compound eyes = 0.21 mm. Compound eye H 1.47× malar space L, and 2.44× compound eyes W. POL 4.95× OOL. Clypeus margin with a blunt projection in the middle (Fig. 13A). Face with raised reticulation but antennal scrobes psilate (Fig. 12A). Mandible bidentate (Fig. 12G). Maxillary palp 3-segmented, length ratio = 3:4:5 (Fig. 13B). Labial palp 2-segmented, length ratio = 3:2 (Fig. 13B). The distance between toruli 0.3× clypeus margin. Antennal formula 11253 and L = 0.55 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:4:1:20:10 (Fig. 12I). Scape L 4.57× W, with sparse trichoid sensillae (Fig. 13C). Pedicel L 1.08× W, with sparse trichoid sensillae (Fig. 13C). Both anelli equal in length and the second one wider (Fig. 13C). All funicular segments equal in length; the first funicular segment L 0.98× W, with 3 multiporous placoid sensillae and 7 chaetica sensillae in antiaxial view; the chaetica sensilla longer than the funicular segment (Fig. 13C). Claval segments slightly wider than funicular segments; the first claval segment L 0.89× W, with 3 multiporous placoid sensillae and 7 chaetica sensillae in antiaxial view. Mesosoma: Mesosoma L = 0.46 mm, W = 0.36 mm, length ratio of pronotum, scutum, scutellum and propodeum = 2:4:6:1. Pronotum, scutum and scutellum with raised reticulation but propodeum psilate in dorsal view (Fig. 12B). Pronotum with collar in ventral view. Scutum with incomplete notauli (Fig. 12B). Scutellum nearly as wide as long, punctures of reticulation lengthened longitudinally (Fig. 13D). Metanotum strongly compressed and the middle covered by scutellum. Propodeum with two longitudinal keels. Forewing L = 1.19 mm, W = 0.53 mm, with 9–13 setae below the marginal vein; length ratio of submarginal vein, marginal vein, postmarginal vein and stigmal vein = 5:3:4:2 (Fig. 12P). Hind wing L = 0.80 mm, W = 0.16 mm; length ratio of submarginal vein and marginal vein = 2:3. Foreleg L = 0.75 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:2:5:4:3 (Fig. 12J). Fore tibia with a curve, bidentate spur reaching the apex of first tarsomere; 2 spines beside spur in axial view and 1 spine in antiaxial views (Fig. 13E, 13F). Fore tarsus 5-segmented, length ratio of each segment = 4:3:3:2:7. Mid leg L = 0.81 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 1:1:3:4:3 (Fig. 12L). Mid tibia with a straight spur; spur L 0.5× the first tarsomere L; 2 spines beside spur in axial view but 2 spines in antiaxial view (Fig. 13G, 13H). Mid tarsus 5-segmented, length ratio of each segment = 7:4:3:2:4. Hind leg L = 1.04 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:3:4:3 (Fig. 12N). Hind tibia with a straight spur; spur L 0.5× the first tarsomere L; 23–25 teeth in axial view and 2 spines beside spur in antiaxial view (Fig. 13I, 13J). Hind tarsus 5-segmented, length ratio of each segment = 6:4:3:2:5. Metasoma: Abdomen without ovipositor sheath L = 0.73 mm. Male: L = 1.69–1.75 mm. Body brown (Fig. 12D). Eyes black (Fig. 12E). Mandible dark brown (Fig. 12H). Antenna pale yellow (Fig. 12E). Legs brown (Fig. 12K, 12M, 12O). Head: Long rectangular in dorsal view (Fig. 12E). L without mandible = 0.43 mm, W = 0.39 mm. Mandible L = 0.28 mm, W = 0.15 mm. Mandible falcate with a fine tooth at the middle (Fig 12H). Clypeus margin concave in the middle. Maxillary palp 4-segmented, length ratio = 3:2:1:2 (Fig. 14B). Labial palp 2-segmented, length ratio = 3:1 (Fig 14B). Compound eye L 3× W. Malar space L 1.73× compound eye L. Toruli close to clypeus margin, with a ridge in the middle. Antennal formula 11153 and L = 0.39 mm; length ratio of scape, pedicel, anelli, funicle and clava = 14:7:1:8:6. Scape L 4.76× W, with sparse trichoid sensillae (Fig. 14A). Pedicel L 3.7× W, with sparse trichoid sensillae (Fig. 14A). The first and third funicular segments swollen, L 0.81× W; other funicular segments L 0.88× W; all funicular segments with trichoid sensillae (Fig. 14A). Claval segments wider than the swollen funicular segments; the first claval segment L 1.03× W, with trichoid sensillae and multiporus placoid sensillae (Fig. 14A). Mesosoma: Subpentagon in dorsal view (Fig. 12F). L = 0.51 mm, W = 0.36 mm; length ratio of pronotum and the fused tergum = 3:2 Pronotum with collar in ventral view. Mesonotum, metanotum and propodeum fused in dorsal view (Fig. 12F). Rudimentary wing vestige present, L = 0.33 mm (Fig. 12F). Foreleg L = 0.91 mm; length ratio of coxa, trochanter, femur, tibia and tarsus = 3:1:4:2:2 (Fig. 12K). Fore tibia with a slightly curve, bidentate spur reaching the fourth tarsomere; 7 spines in axial view and 8 spines in antiaxial view (Fig. 14C, 14D). Fore tarsus 5-segmented, length ratio of each segment = 1:1:1:1:5. page 22 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Fig. 12. Sycoscapter ishiianus sp. nov. A, Female head, front; B, Female mesosoma, dorsal; C, Female habitus, lateral; D, Male habitus, lateral; E, Male head, dorsal; F, Male mesosoma, dorsal; G, Female left mandible, ventral; H, Male left mandible, dorsal; I, Female antenna; J, Female right foreleg; K, Male right foreleg; L, Female right mid leg; M, Male right mid leg; N, Female right hind leg; O, Male right hind leg; P, Female forewing. Scale bar = 0.1 mm if no number is noted. page 23 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Fig. 13. Scanning electron images of female Sycoscapter ishiiaus sp. nov. A, Toruli and epistomal margin; B, Maxillary palps and labial palps; C, Anelli and the first funiculus; D, Scutellum; E, Left fore tibia, axial; F, Right tibia, antiaxial; G, Left mid tibia, axial; H, Right mid tibia, antiaxial; I, Right hind tibia, axial; J, Left hind tibia, antiaxial. Scale bar = 0.03 mm. page 24 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan Fig. 14. Scanning electron images of male Sycoscapter ishiianus sp. nov. A, Antenna; B, Maxillary palps and labial palps; C, Left fore tibia, axial; D, Right tibia, antiaxial; E, Left mid tibia, axial; F, Right mid tibia, antiaxial; G, Right hind tibia, axial; H, Left hind tibia, antiaxial. Scale bar = 0.03 mm. page 25 of 34Zoological Studies 63:34 (2024) © 2024 Academia Sinica, Taiwan functional dioecious figs have been documented in various studies (Kerdelhué and Rasplus 1996; Weiblen 2000), with the most notable distinction being the layer structure composed of galls and seeds, which forms multiple layers in monoecious figs and a single layer in functional dioecious figs (Kerdelhué and Rasplus 1996). Similarly, the presence of the wing vestige in male wasps of the genera Otitesella and Walkerella, which belong to the pteromalid tribe Otitesellini and are primarily associated with monoecious fig trees (Jousselin et al. 2006; Ma et al. 2013), suggests that these males may have evolved similar habits or behaviors inside their native figs. Therefore, the wing vestige is more likely an adaptive convergent character rather than a synapomorphic character. This study, including a thorough collection effort, represents the first comprehensive taxonomic assessment of Sycoscapter wasps associated with monoecious figs in Taiwan. Given the reported keystone status of fig species (Mackay et al. 2018), it is crucial to identify species composition in fig-wasp communities and understand their interactions within multitrophic ecosystems. Although taxonomic studies of Sycoscapter species associated with functional dioecious figs remain to be conducted, this study not only contributes to the knowledge of chalcidoid fauna in Taiwan but also provides insights into the mechanism underlying the maintenance of this intricate ecosystem. CONCLUSIONS Wasps of the genus Sycoscapter (Hymenoptera: Pyeromalidae) associated with monoecious Ficus species in Taiwan were investigated. Both phylogenetic and morphological results indicated presence of five species among those wasps, including four new species: S. piceoscapus sp. nov., S. monticola sp. nov., S. ishiianus sp. nov. and S. littoralis sp. nov. This discovery not only records new members of Taiwanese chalcid fauna but also provides insight into fig-wasp symbiosis. Acknowledgment: We thank Ayako Sasaki, Junko Kusumi and Kouichi Arimoto for collecting samples in Japan. We also thank Chi-Feng Lee and Junsuke Yamasako for their kind help during specimen examination at Taiwan Agricultural Research Institute, Taichung, Taiwan; and Institute for Agro-Environmental Sciences, Ibaraki, Japan. We are grateful to Hengchun Research Center, Forestry Research Institute and Lanyu township office for their kind help during our field collection. Authors’ contributions: PAC and HYT conceived the ideas; WBY and HYT developed the research program; PAC, ZHS and HYT collected the data; PAC, WBY and ZHS carried out the analyses; PAC drafted the manuscript; all authors have read, edited and agreed to the published version of the manuscript. Competing interests: The authors declare that they have no competing interests. Availability of data and materials: All specimens are deposited in museum collections stated in the paper. All DNA sequence data has been deposited in GenBank (accession number PP111396-PP111462 and PP162908PP162951). Consent for publication: All authors consent to the publication of this manuscript. Ethics approval consent to participate: No applicable. REFERENCES Ahmed S, Compton SG, Butlin RK, Gilmartin PM. 2009. Wind-borne insects mediate directional pollen transfer between desert fig trees 160 kilometers apart. Proc Natl Acad Sci USA 106:20342– 20347. doi:10.1073/pnas.0902213106. 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Monoecious Ficus species in Taiwan and their distributions according to Flora of Taiwan Vol. 2 (2nd edition). (download) Fig. S1. Phylogenetic tree of the Sycoscapter species associated with monoecious figs in Taiwan and other congeners based on 28S genes. The values at the nodes are the ultrafast bootstraps and posterior possibilities for maximum likelihood (ML) and Bayesian inference (BI) analyses, respectively. (download) Fig. S2. Lectotype of Sycoscapter gajimaru (Ishii). A, female specimen; B, label. (download) page 34 of 34Zoological Studies 63:34 (2024)