First records of Epeus bicuspidatus and description of a new species of Epeus (Araneae, Salticidae) from Vietnam

Biodiversity Data Journal 13: e172899 doi: 10.3897/BDJ.13.e172899 Taxonomy & Inventories First records of Epeus bicuspidatus and description of a new species of Epeus (Araneae, Salticidae) from Vietnam Duc-Toan Vu , Van-Tang Duong , Dinh-Sac Pham ‡ Faculty of Agriculture and Forestry, Tay Bac University, Quyet Tam ward, Son La, Vietnam § Vietnam National Museum of Nature (VNMN), Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam | Graduate University of Sciences and Technology (USTH), Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam Corresponding author: Dinh-Sac Pham ([email protected]) Academic editor: Yanfeng Tong Received: 23 Sep 2025 | Accepted: 20 Nov 2025 | Published: 01 Dec 2025 Citation: Vu D-T, Duong V-T, Pham D-S (2025) First records of Epeus bicuspidatus and description of a new species of Epeus (Araneae, Salticidae) from Vietnam. Biodiversity Data Journal 13: e172899. https://doi.org/10.3897/BDJ.13.e172899 ZooBank: urn:lsid:zoobank.org:pub:8AB4C68E-1588-4114-B3D1-B194AF9EC788 Abstract Background Epeus is a genus of jumping spiders (Salticidae) comprising 20 species, four of which have been recorded in Vietnam. New information In this paper, we present descriptions and illustrations of two jumping spider species of the genus Epeus from Vietnam. Epeus bicuspidatus (Song, Gu & Chen, 1988) is recorded from the country for the first time, while Epeus taybac Vu & Pham, sp. nov., is described here as new to science. These findings improve the current understanding of Epeus diversity in Vietnam, bringing the total number of known species of this genus in the country to six. ‡ § §,| © Vu D et al. 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. Keywords Epeus, new species, Salticidae, species diversity, Vietnam Introduction The genus Epeus Peckham & Peckham, 1885 (Araneae, Salticidae) currently comprises 20 valid species, primarily distributed across Southeast Asia (WSC 2025). Species of this genus are distinguished by several characteristic morphological features, particularly in the male palpal organ, which includes a flattened and elongated cymbium, a characteristic apophysis (CA) directed towards the tibia, a tegular bulb (TB) bearing a tongue-like process and a filiform embolus. The legs are densely covered with setae and bear numerous spines. In females, the epigyne is characterised by long, translucent copulatory ducts (CD) that form several loops (Zabka 1985, Peng and Li 2002, Meng et al. 2015). To date, four species of Epeus have been recorded from Vietnam: E. glorius, E. flavobilineatus, E. albus and E. phamtri (Zabka 1985, Patoleta et al. 2020, Tam and Hill 2025, Tam and Thuy 2025, Hill 2025). Despite these records, the genus remains poorly studied in the country and additional species are likely to be discovered through continued fieldwork and taxonomic research. Between May 2024 and March 2025, field surveys were conducted in Son La, Lao Cai and Quang Tri Provinces of Vietnam. These surveys yielded the first records of Epeus bicuspidatus (Song, Gu & Chen, 1988) from Vietnam, along with several specimens exhibiting the general morphological characteristics of the genus Epeus, yet differing significantly in key diagnostic traits from all currently described species. These findings represent important new distributional records and contribute to the growing body of knowledge on Salticidae diversity at both national and global scales. Materials and methods All specimens were preserved in 75% ethanol. Female epigyna were cleared in a 10% potassium hydroxide (KOH) solution at room temperature for approximately 12 hours and subsequently stored in small glass vials with their respective specimens. The left male palp was used for morphological descriptions and illustrations. Specimens were examined and illustrated using Olympus BX51 and SZ61 stereomicroscopes, with measurements taken using an Olympus STM4 measuring microscope. Photographs were captured with a Sony A7 IV digital camera mounted on the Olympus BX51 and SZ61 microscopes. Focus-stacked images were produced using Zerene Stacker software. All measurements are reported in millimetres (mm). Leg measurements are presented as total length, with segment lengths given in the following order: femur, patella + tibia, metatarsus and tarsus. Terminology used in the text and figure legends follows Patoleta et al. (2020). 2Vu D et al Abbreviations used in the text and figures are as follows: ALE anterior lateral eye; AME anterior median eye; CA cymbial apophysis; CD copulatory duct; CO copulatory opening; E embolus; EP epigynal pocket; FD fertilisation duct; GD glandular duct; PLE posterior lateral eye; PME posterior median eye; PTA proximal tegular apophysis; TRA retrolateral tibial apophysis; S spermatheca; SD sperm duct; TB tegular bump; TL tongue-like flap. Taxon treatments Epeus bicuspidatus (Song, Gu & Chen, 1988) Nomenclature Plexippoides bicuspidatus: Song et al. (1988): 71, figs. 6-8 (description of male). Epeus bicuspidatus (Song, Gu & Chen, 1988): Peng et al. (1993): 48, figs. 121-124 (transferred from Plexippoides); Song et al. (1999): 508, figs. 291 N-O (♂). Materials a. scientificName: Epeus bicuspidatus (Song, Gu & Chen, 1988); order: Araneae; family: Salticidae; genus: Epeus; country: Vietnam; countryCode: VN; stateProvince: Son La; locality: Tu Le Commune; verbatimElevation: 1513 m; verbatimLatitude: 21°45′16″N; verbatimLongitude: 104°14′43″E; verbatimCoordinateSystem: WGS84; eventDate: 22May 2024; eventRemarks: collected by Duc-Toan Vu; individualCount: 2; sex: 1 male, 1 female; lifeStage: adult; catalogNumber: TBU-ARA-SAL-002.3 to 002.4; occurrenceID: 805D7F94-6204-5C54-A708-9564FA92D6AD b. scientificName: Epeus bicuspidatus (Song, Gu & Chen, 1988); order: Araneae; family: Salticidae; genus: Epeus; country: Vietnam; countryCode: VN; stateProvince: Quang Tri; locality: Dakrong Nature Reserve; verbatimElevation: 965 m; verbatimLatitude: 16°77′89″N; verbatimLongitude: 106°84′95″E; verbatimCoordinateSystem: WGS84; eventDate: 12July 2024; eventRemarks: collected by Dinh-Sac Pham; individualCount: 1; sex: female; lifeStage: adult; catalogNumber: VNMN-SAL-079; occurrenceID: 4E813C9D-1B5A-5E63-8FDF-10FF9DADE4BA Description Male: Total length 6.91. Carapace 2.55 long, 2.12 wide. Abdomen 3.44 long, 1.48 wide. Eye sizes and interdistances: AME 0.62, ALE 0.29, PME 0.08, PLE 0.26; distance ALE–PME 0.35, ALE–PLE 0.76. Leg measurements: I 6.16 (1.96, 0.91, 1.60, 1.04, 0.65); II 7.34 (2.24, 0.86, 1.51, 1.74, 0.99); III 7.21 (2.05, 0.93, 1.49, 1.78, 0.96); IV 6.93 (1.86, 0.79, 1.64, 1.82, 0.82). Female: Total length 6.94. Carapace 2.78 long, 2.01 wide. Abdomen 3.52 long, 1.36 wide. Eye sizes and interdistances: AME 0.69, ALE 0.38, PME 0.14, PLE 0.31; distance ALE–PME 0.35, ALE–PLE 0.81. Leg measurements: I 7.17 (2.22, 1.03, 1.85, 1.26, 0.81); II 6.70 (2.13, 0.93, 1.73, 1.18, 0.73); III 7.42 (2.46, 0.68, 1.75, 1.71, 0.82); IV 6.75 (2.10, 0.71, 1.63, 1.49, 0.82). First records of Epeus bicuspidatus and description of a new species of ... 3 Morphological diagnoses of the male specimens are illustrated in Fig. 1A, B and Fig. 2, while those of the female specimens are depicted in Fig. 1C–F. These closely correspond to the descriptions provided by Peng and Li (2002) and Meng et al. (2015). Epeus taybac Vu & Pham, sp. nov. • ZooBank 7BFF4FE7-1CAF-4AED-A627-EE6F46C68A2A Materials Holotype: a. scientificName: Epeus taybac sp. nov.; order: Araneae; family: Salticidae; genus: Epeus; country: Vietnam; countryCode: VN; stateProvince: Son La; locality: Muong La Commune, Pieng Village; verbatimElevation: 680 m; verbatimLatitude: 21°34′57″N; verbatimLongitude: 104°04′58″E; verbatimCoordinateSystem: WGS84; eventDate: 22May 2024; eventRemarks: collected by Duc-Toan Vu; individualCount: 1; sex: 1 male; Figure 1. Epeus bicuspidatus. A Male, dorsal view; B Male, ventral view; C Female, dorsal view; D Female, ventral view; E Epigyne, ventral view; F Vulva, dorsal view. Scale bars: A–D = 1.0 mm; E–F = 0.1 mm.  4Vu D et al lifeStage: adult; catalogNumber: TBU-ARA-SAL-003-1; occurrenceID: EE56D8CDD43D-5C2B-AAFB-4E5F20090640 Paratype: a. scientificName: Epeus taybac sp. nov.; order: Araneae; family: Salticidae; genus: Epeus; country: Vietnam; countryCode: VN; stateProvince: Son La; locality: Muong La Commune, Pieng Village; verbatimElevation: 680 m; verbatimLatitude: 21°34′57″N; verbatimLongitude: 104°04′58″E; verbatimCoordinateSystem: WGS84; eventDate: 22May 2024; eventRemarks: collected by Duc-Toan Vu; individualCount: 1; sex: female; lifeStage: adult; catalogNumber: TBU-ARA-SAL-003-2; occurrenceID: 068C9472D849-5CDA-A0AD-6111C93FF431 Other material: a. scientificName: Epeus taybac sp. nov.; order: Araneae; family: Salticidae; genus: Epeus; country: Vietnam; countryCode: VN; stateProvince: Son La; locality: Chieng Coi Ward, Na Phum Village; verbatimElevation: 875 m; verbatimLatitude: 21°18′23″N; verbatimLongitude: 103°51′03″; verbatimCoordinateSystem: WGS84; eventDate: 11March 2025; eventRemarks: collected by Duc-Toan Vu; individualCount: 1; sex: 1 male; lifeStage: adult; catalogNumber: TBU-ARA-SAL-003-3; occurrenceID: 6B109DDB-74B5-5ED6-B4F2-CEE7CE57FC12 Figure 2. Epeus bicuspidatus, left palp habitus. A Ventral view; B Dorsal view; C Retrolateral view; D–E Prolateral views. Scale bars: 0.1 mm.  First records of Epeus bicuspidatus and description of a new species of ... 5 Description Male. Total length 7.74. Carapace 2.84 long, 2.33 wide. Abdomen 3.62 long, 1.48 wide. Eye sizes and interdistances: AME 0.72, ALE 0.32, PME 0.09, PLE 0.33, ALEPME 0.34, ALE-PLE 0.81. Legs measurements: I 9.76 (2.81, 1.34, 2.79, 2.01, 0.81), II 7.72 (2.28, 1.12, 2.04, 1.58, 0.70), III 9.04 (2.95, 1.10, 1.91, 2.18, 0.90), IV 7.95 (2.35, 1.00, 1.77, 1.85, 0.98). The carapace is high and elevated, with a posterior slope, exhibiting a colouration ranging from yellow-brown to dark brown (Fig. 3A). A crest of erect hairs is present along the carapace (Fig. 3C). The sternum is oval, slightly wider posteriorly, brown with a lighter margin. The clypeus is dark brown, covered with brown and white hairs and bristles. Chelicerae, endites and labium are dark brown, chelicerae with two promarginal teeth and one retromarginal tooth (Fig. 3D). Legs are long and slender; legs I, II and III are dark brown and covered with setae, except for the metatarsus and tarsus, which are yellowish-brown, while leg IV is entirely yellowish-brown. The abdomen is slender and cylindrical, with a dark brown dorsum featuring two lightcoloured lateral stripes and a dark brown ventral surface. The male palpal organ (Fig. 4) exhibits a filiform embolus that is long and arises at the 6:00 o’clock position, coiling approximately 180°. A well-developed, tongue-like flap is present at a 90° angle on the tegular bump. The proximal tegular apophysis is slender, sharp and curved (Fig. 4A, B and E). In dorsal view, the cymbium is nearly Figure 3. Epeus taybac sp. nov., male habitus. A Dorsal view; B Ventral view; C Frontal view; D Chelicera, posterior view. Scale bars: 1.0 mm.  6Vu D et al triangular, with the retrolateral edge concave, tapering anteriorly and covered with long white setae. The cymbial apophysis is elongate and slender, with its distal end slightly curved. The retrolateral tibial apophysis is stout, slightly blunt and directed anterodorsally (Fig. 4C and F). Female. Total length 5.50. Carapace 2.62 long, 1.48 wide. Abdomen 2.87 long, 1.32 wide. Eye sizes and interdistances: AME 0.52, ALE 0.16, PME 0.06, PLE 0.21; ALE– PME 0.25, ALE–PLE 0.62. Legs measurements: I 5.58 (1.70, 0.81, 1.57, 1.01, 0.49), II 5.47 (1.69, 0.78, 1.31, 1.08, 0.61), III 6.13 (1.93, 0.68, 1.34, 1.53, 0.65), IV 5.91 (1.78, 0.52, 1.44, 1.46, 0.71). The carapace is similar in shape to that of the male, exhibiting a pale yellow to yellow-orange colouration. The anterior half of the carapace is covered with colourless and white setae (Fig. 5A). The area surrounding the anterior median eyes is yellow, while the regions around the other eyes are dark brown to black-brown, interspersed with white setae. The clypeus is densely covered with white setae (Fig. 5 C). Chelicerae are yellow, whereas the endites, labium and sternum are pale yellow. Legs and palps are predominantly pale yellow, with the exception of the metatarsi and tarsi, which exhibit a yellow-orange hue. The abdomen is slender and dorsally pale yellow, adorned with clusters of white spots arranged along the lateral margins. The ventral surface is pale yellow. The epigynal plate is longer than wide (Fig. 6A), featuring cup-shaped copulatory openings. The internal copulatory ducts are long and expansive, forming numerous loops. Figure 4. Epeus taybac sp. nov., holotype left palp habitus view. A, E prolateral view; B ventral view; C, F retrolateral view; D dorsal view. Scale bars: 0.1 mm.  First records of Epeus bicuspidatus and description of a new species of ... 7 Figure 5. Epeus taybac sp. nov., female habitus. A Dorsal view; B Ventral view; C Frontal view; D Chelicera, posterior view. Scale bars: 1.0 mm.  Figure 6. Epeus taybac sp. nov. A Epigyne, ventral view; B Vulva, dorsal view. Scale bars: 0.1 mm.  8Vu D et al Diagnosis The male genitalia of Epeus taybac sp. nov. resemble those of E. albus, E. daiqini and E. glorius. However, E. taybac sp. nov. can be distinguished by the following characters: the presence of a proximal tegular apophysis (PTA), which is long, curved and located posterior to the tegular bump (TB) on the patella side (Fig. 4A, B and E); the cymbial apophysis (CA) is long and pointed when viewed ventrally, with the tip slightly curved outwards (Fig. 4B), in contrast to the blunt tip observed in E. albus (Tam and Thuy 2025) and considerably longer than the CA of E. daiqini (Patoleta et al. 2020), lacking the small serrated apophyses present in E. glorius (Zabka 1985). The retrolateral tibial apophysis (RTA) is approximately one-third the length of the tibia, stout, slightly blunt and directed anterodorsally (Fig. 4C and F). Females of the new species are morphologically similar to E. albus, sharing wide copulatory openings and a comparable copulatory duct arrangement when viewed ventrally (Fig. 6A). However, E. taybac sp. nov. can be differentiated by the more compact arrangement of the copulatory ducts (CD), which form an oval shape in dorsal view (Fig. 6). Etymology The species is named after its type locality: taybac refers to “Tây Bắc,” the Vietnamese name for the north-western region of Vietnam. Acknowledgements We are especially grateful to Professor Yanfeng Tong, the subject editor, for his valuable guidance. We also wish to express our sincere thanks to Professor Vu Dinh Thong (Institute of Biology, Vietnam Academy of Science and Technology) for his insightful comments. This study was supported by the Vietnam Academy of Science and Technology (Grant No. ĐL0000.03/24-25). References • Hill DE (2025) Identification of jumping spiders placed in the genus Epeus (Araneae: Salticidae: Plexippini: Plexippina). Peckhamia 330.1: 1‑50. • Meng X, Zhang Z, Shi A (2015) Description of two unknown females of Epeus Peckham & Peckham from China (Araneae: Salticidae). Zootaxa 3955 (1): 147‑50. https://doi.org/ 10.11646/zootaxa.3955.1.11 • Patoleta BM, Gardzińska J, Żabka M (2020) Salticidae (Arachnida, Araneae) of Thailand: new species and records of Epeus Peckham & Peckham, 1886 and Ptocasius Simon, 1885. PeerJ 8 https://doi.org/10.7717/peerj.9352 • Peng X, Li S (2002) A review of the genus Epeus Peckham & Peckham (Araneae: Salticidae) from China. Oriental Insects 36 (1): 385‑392. https://doi.org/ 10.1080/00305316.2002.10417336 First records of Epeus bicuspidatus and description of a new species of ... 9