Zoological Studies 39(2): 123-132 (2000) The Spider Family Theridiidae (Arachnida: Araneae) from Orchid Island, Taiwan: Descriptions of Six New and One Newly Recorded Species Hajime Yoshida1,*, I-Min Tso2,3 and Lucia Liu Severinghaus3 17-16, Kagota 2 Chome, Yamagata-shi, Yamagata 990-2484, Japan 2Department of Biology, Tunghai University, Taichung, Taiwan 407, R.O.C. 3Institute of Zoology, Academia Sinica, Taipei, Taiwan 115, R.O.C. (Accepted February 2, 2000) Hajime Yoshida, I-Min Tso and Lucia Liu Severinghaus (2000) The spider family Theridiidae (Arachnida: Araneae) from Orchid Island, Taiwan: descriptions of six new and one newly recorded species. Zoological Studies 39(2): 123-132. From a preliminary spider fauna investigation conducted in 1993 and 1997 on Orchid Island, Taiwan, 17 species of the spider family Theridiidae are recorded. Six of them are described as new species under the names, Argyrodes nigroris, Chrosiothes fulvus, Chrosiothes taiwan, Chrysso orchis, Achaearanea lanyuensis, and Achaearanea quadrimaculata. Theridion xianfengensis Zhu and Song, 1992 is recorded for the first time from Taiwan. This paper describes the external morphology of these 7 new/new record species and reports the synonymies and distribution records of the other 10 theridiid species. Key words: Spider fauna, New species, Orchid Island, Theridiidae. Currently, spider diversity in most areas of Tai- trips to Orchid Island to study the behavioral ecology wan is severely understudied. Islands off both the of spiders. During those trips, we also made some east and west coasts of Taiwan have received even preliminary collections to assess the feasibility of fu- less attention. One such island is Orchid Island ture comprehensive spider diversity studies. Despite (Lanyu in Chinese; 22°N, 121°E, area 45 km2), a the limited effort expended, we have obtained a large tropical island in a chain of islands stretching from number of specimens from various families that the Philippines, Taiwan, and the Ryukyus to Japan. were previously undescribed. Here, we report the Located 91 km off the southeastern coast of Taiwan, results of a preliminary taxonomic study we per- Orchid Island’s climate is characterized by relatively formed on Orchid Island’s theridiid diversity. high temperatures (average 22.4 °C), high humidity Among the approximately 35 000 species of spi- (more than 90%), and high annual rainfall (more than ders documented worldwide (Foelix l996), comb- 2600 mm) (Chen 1982). Due to its tropical climatic footed spiders of the family Theridiidae are one of pattern, Orchid Island is covered by dense primary the most diverse families, and currently 2350 spe- forest which is relatively unexplored compared with cies have been reported (Zhu l998). A recent com- forests in Taiwan. Previous expeditions focusing on prehensive review of theridiid morphology, ecology, the diversity of selected groups (mainly vertebrates systematics, and biogeography is available in Zhu and flowering plants) have revealed that Orchid (1998). In Taiwan, among all the spider families Island’s fauna and flora both contain components documented, Theridiidae is the second most that are unseen in Taiwan but are common in the diverse, and to date, 45 species have been reported Philippines (Shen 1998). Therefore, Orchid Island (Chen 1996, Yoshida 1996, Yoshida et al. 1998). should have a unique spider diversity that differs Here, we report on 17 species of theridiids collected from known Taiwanese fauna. from Orchid Island. Among them, 4 species of In 1993 and 1997, we conducted several field Argyrodes were previously reported (Yoshida et al. *To whom correspondence and reprint requests should be addressed. 123 124 Zoological Studies 39(2): 123-132 (2000) 1998); 6 species are recognized as new, one is con- MOA, anterior width: posterior width: length in the sidered a possibly new species, one is recorded from ratio of 17:15:17. Leg formula: 4, 1, 2, 3. Genital Taiwan for the first time, and the other five are also organs as shown in figures 2-3: seminal receptacles found in Taiwan. This result increases the number of 2 pairs; ducts thick, connecting to top of large semi- Taiwanese theridiid species to 52. nal receptacles. Coloration: Carapace dusky brown, lighter in head region. Chelicerae, maxillae, and labium gray- METHODS ish dusky brown. Sternum dusky brown. Legs yel- lowish brown; femora, patellae, tibiae, and metatarsi Specimens recorded in this paper were col- with distal dusky bands; 1st and 2nd tibiae and meta- lected by Y. J. Fang and the authors from 4 major tarsi with ventral dusky flecks. Abdomen black with sites on Orchid Island (Taitung County), Taiwan in grayish flecks as shown in figure 1; venter grayish August 1993 and February to June and October to dusky brown; epigynum brown. December 1997 (10 field trips). The 4 major collec- Specimen examined: 1 ð, near Light House, tion sites were Light House (22°05’N, 121°29’E), Orchid Island, Taitung County, Taiwan, 18-II-1997, Y. Yunghsing Farm (22°01’N, 121°34’E), Chungai J. Fang leg. (THU-Ar-970001). Bridge (22°00’N, 121°33’E), and Tienchih (22°01’N, Remarks: This species seems to be new. We 121°33’E). Collections were conducted both during will assign a new scientific name when more speci- the day and at night by hand and sweep net. Two mens are available. specimens of a new species used in this paper were collected by M. Yoshimura from Chihpen (22°41’N, Dipoena mustelina (Simon, 1888) 121°00’E, Taitung County) and Kenting (22°02’N, (Fig. 4) 120°47’E, Pingtung County), on the main island of Taiwan. Euryopis mustelina Simon, 1888, p. 251; Yaginuma 1960, p. 34, The holotypes and some paratypes of the new pl. 7, fig. 42. Dipoena mustelina: Yaginuma, 1967, p. 88; Yaginuma 1986, p. species are deposited in the collection of the Depart- 42, pl. 10, fig. 3, text-fig. 23-3; Zhu 1992, p. l09, figs. 5-6; ment of Biology, Tunghai University, Taiwan (THU- Zhu 1998, p. 240, fig. 157. Ar-) and the National Science Museum (Natural History), Tokyo (NSMT). Female: Total length 2.74. Carapace length All measurements are given in millimeters 1.05; width 1. Abdomen length 1.84; width 1.76. First (mm), except for ratios and leg formulae. The abbre- leg: femur 1.05; patella and tibia 1.21; metatarsus viations used in this paper are as follows: ALE, ante- 0.87; tarsus 0.45. Second patella and tibia 1.05; 3rd rior lateral eye(s); AME, anterior median eye(s); patella and tibia 1; 4th patella and tibia 1.5. MOA, median ocular area; PLE, posterior lateral eye Coloration: Basal color yellowish white. Cara- (s); and PME, posterior median eye(s). The mea- pace with a median dusky fleck. Abdomen with surements described in this study are based on the dusky flecks as shown in figure 4; venter with a small holotype and 1 specimen of sex different from that of dusky fleck between epigynum and spinnerets. ð the holotype. Variations in length of body, carapace, Specimens examined: 1 , Yunghsing Farm, and abdomen are given when additional specimens Orchid Island, Taitung County, Taiwan, 14-IV-1997, ñ are available for measurements. I.M. Tso leg. (THU-Ar-97002); 1 , Tienchih, Orchid Island, Taitung County, Taiwan, 20-XII-1997, I.M. Tso leg. (THU-Ar-970003). Species Accounts Distribution: Taiwan, China, Japan, Korea, and Dipoena sp. Indonesia. (Figs. 1-3) Female: Total length 1.47. Carapace length 0. Steatoda cingulata (Thorell, 1890) 79; width 0.66. Abdomen length 0.97; width 0.87. Stethopoma cingulata Thorell, 1890, p. 289. First leg: femur 0.66; patella and tibia 0.68; metatar- Steatoda albilunate: Yaginuma, 1960, p. 34, pl. 7, fig. 41. sus 0.39; tarsus 0.47, 2nd patella and tibia 0.61; 3rd Steatoda cavernicola: Yaginuma, 1986, p. 39, pl. 9, fig. 5, text-fig. patella and tibia 0.47; 4th patella and tibia 0.74. 21-5. Diameters of AME: ALE: PME: PLE in the ratio Steatoda cingulata: Zhu, 1998, p. 329, fig. 220. Lithyphantes cavaleriei Schenkel, 1963, p. l02, fig. 60. of 7:5:7:6. AME 5/7 their diameter apart and 2/7 Lithyphantes cavernicola Bösenberg and Strand, l906, p. 154, pl. from ALE. PME 4/7 their diameter apart and 6/7 from 5, fig. 57; Lee 1964, p. 26, pl. 5, fig. N. PLE. ALE and PLE almost abutting each other. Asagena albilunata Saito, 1939, p. 51, pl. 1, fig. 3, text-fig. 6-3. Yoshida et al. − Theridiidae from Orchid Island 125 Specimen examined: 1 ñ, Light House, Orchid 0.82. First leg: femur 1.11; patella and tibia 1.11; Island, Taitung County, Taiwan, 18-III-1997, I.M. Tso metatarsus 0.79; tarsus 0.5. Second patella and leg. (THU-Ar-970022). tibia 0.74; 3rd patella and tibia 0.45; 4th patella and Distribution: Taiwan and Orchid Island. Widely tibia 0.63. distributed in Japan, China, and Southeast Asia. Carapace elongated and flattened; eye region projecting; clypeus with small concavity. Diameters Argyrodes nigroris sp. nov. of AME: ALE: PME: PLE in the ratio of 4:3:2:2. AME (Figs. 5-10) 5/4 their diameter apart and 1/4 from ALE. PME twice their diameter apart and 3/4 from PLE. MOA, Male: Total length 1.95. Carapace length 0.79; anterior width: posterior width: length in the ratio of width 0.55. Abdomen length 1.16; width 0.89; height 5:4:4. Abdomen suboval; dorsum, epigastric area, Figs. 1-10. 1-3. Dipoena sp. 1, female carapace and abdomen, dorsal view; 2, epigynum, ventral view; 3, female genitalia, dorsal view. 4. Dipoena mustelina (Simon, 1888), female carapace and abdomen, dorsal view.