Acta Arachnologica, 69 (2): 75–76, December 20, 2020

[Short Communication] (formerly Corinnomma) suaverubens (Simon 1896) (Erthal Jr. & Tonhasca Jr. 2001; Fowler 1984; Hawkeswood 2003). Although laboratory experiments have shown that generalist Field observation on of an orb predator coloripes (L. Koch 1873) can invade other ’ webs and capture the hosts, they do not use any web (Araneae: Araneidae) by the specialized behavior and were sometimes killed by the host spiders (Jackson & Poulsen 1990; documented as “Supunna corinnid , Corinnomma severum picta”, a synonym of the species). To date, no other scientif- ic papers have reported araneophagic events of web-builders (Araneae: ) by corinnid spiders in the field. During a fauna survey of spiders in Thailand, we ob- 1* 2 Yuya Suzuki , Booppa Petcharad , Thanakorn served a case of predation of an orb web spider by a corin- Into2 & Akio Tanikawa3 nid spider in the host spider’s web. The event was observed on 20 December 2019 in the forest of Kaeng Krachan 1Graduate School of Life and Environmental Sciences, University National Park (12.880703N, 99.632178E), Kaeng Krachan of Tsukuba, 1-1-1 Tennodai,Tsukuba, Ibaraki 305-8572, Japan District, Phetchaburi Province, Thailand. A corinnid spider 2Department of Biotechnology, Faculty of Science and Tech- was found hanging on the center of the orb web, holding the nology, Thammasat University, Rangsit, Pathum Thani, 12120 body of the host spider between its (Fig. 1). After Thailand taking a picture, both spiders were collected and preserved 3Laboratory of Science, School of Agriculture and in 75% ethanol. After preservation, morphological features Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, of the specimens were observed under a stereoscopic micro- Tokyo, 113-8657 Japan scope (Nikon AZ100M, Japan) and photographs were taken E-mail: [email protected], *Corresponding author with microscope imaging software (Nikon NIS-Elements D 4.20.00 64-bit, Japan). Through morphological observation, the predator was Abstract ― In this short paper, we report the predation identified as a female adult Corinnomma severum (Thorell of an orb-weaving spider Neoscona sp. (Araneae: Ara- 1877) (Figs. 2–3), which have already been recorded in neidae) by a corinnid sac spider Corinnomma severum Thailand (Deeleman-Reinhold 1993). The prey spider was (Araneae: Corinnidae) from Thailand. To the best of determined to be a juvenile Neoscona sp. (Araneidae) (Figs. our knowledge, this is the first report of predation of 4–5). Body lengths of the predator and the prey were 8.89 web-building spider by a spider of the Corin- mm and 5.42 mm, respectively. Whitish fluid was solidified nomma observed in the field. at the patella of left leg I and at the basal part of the prey’s abdomen (Figs. 4–5, arrows), suggesting that these parts Key words ― Kaeng Krachan National Park, natural were bitten by the predator. Both specimens were deposited diet, Neoscona, predation, Southeast Asia in the collection of the Department of Zoology, National Museum of Nature and Science, Tsukuba under the same depository number (NSMT-Ar. 17307). To the best of our knowledge, this is the first report of pre- Araneophagy (i.e., eating other spiders) is a widespread dation of web-building spider by spiders of the genus Corin- behavior among spiders (Pekár et al. 2011). Specifically, nomma. Also, this is the first time that such a case has been the predation of web-building spiders by cursorial spiders observed by corinnid spiders under natural conditions. As has been getting attention from researchers because of their this was a snapshot, it is difficult to determine whether the specialized web-invading and prey capturing tactics (e.g., predation was a consequence of araneophagic behavior (i.e. Jackson & Blest 1982). Web-invasion and araneophagy are C. severum spontaneously invaded the web and captured recognized behaviors in at least nine families: Araneidae the host spider by specialized tactics) or occasional preda- (Eberhard 1983), Archaeidae (Legendre 1961), Gnaphosidae tion (i.e. C. severum accidentally dropped to the web and (Jarman & Jackson 1986), Lamponidae (e.g., Platnick 2000), attacked the host spider). It is possible that the predation of Mimetidae (e.g., Jackson & Whitehouse 1986), Oxyopidae web-building spider reported in this paper is only one of the (Oliveira Gonzaga et al. 1998); Pholcidae (Jackson & Rowe versatile predatory tactics of C. severum, as has been report- 1987); Salticidae (e.g., Wilcox et al. 1996) and ed in N. soloripes which forages prey by cursorial hunting (e.g., Whitehouse 1987). and web-building, as well as by web-invading (Jackson & Spiders of the family Corinnidae (also called corinnid sac Poulsen 1990). Further field studies and laboratory experi- spiders), are a group of cursorial predators that includes both ments are needed to reveal the prevalence of araneophagy in euryphagous (Pekár & Jarab 2011; Oliveira 1988) and myr- corinnid spiders, and how they specialize in eating spiders. mecophagous species, such as Attacobius attarum (Roewer 1935), Falconina gracilis (Keyserling 1891), and Kolora 76 Y. Suzuki, B. Petcharad, T. Into & A. Tanikawa

rizopes sp. (Araneidae), and the defensive behavior of its prey. J. Bombay Nat. Hist. Soc., 79: 522–524. Erthal Jr., M. & Tonhasca Jr., A. 2001. Attacobius attarum spiders (Corinnidae): myrmecophilous predators of immature forms of the leaf-cutting ant Atta sexdens (Formicidae). Biotropica, 33: 374–376. Fowler, H. G. 1984. Note on a clubionid spider associated with attine ants. J. Arachnol., 12: 117. Hawkeswood, T. J. 2003. : an introduction to their classification, biology and distribution. Pensoft, Sofia‐Moscow. 264pp. Jackson, R. R. & Poulsen, B. A. 1990. Predatory versatility and intra- specific interactions of Supunna picta (Araneae: Clubionidae). N. Z. J. Zool., 17: 169–184. Jackson, R. R. & Whitehouse, M. E. A. 1986. The biology of New Zealand and Queensland pirate spiders (Araneae, Mimetidae): Ag- gressive mimicry, araneophagy and prey specialization. J. Zool., 210: 279–303. Jackson, R. R. & Blest, A. D. 1982. The biology of Portia fimbri- ata, a web-building (Araneae: Salticidae) from Queensland: utilization of webs and predatory versatility. J. Zool., 196: 255–293. Jackson, R. R. & Rowe, R. J. 1987. Web-invasion and araneophagy by New Zealand and Australian pholcid spiders, N. Z. J. Zool., 14:1, 139–140. Jarman, E. A. R. & Jackson, R. R. 1986. The biology of Taieria ere- bus (Araneae, Gnaphosidae), an araneophagic spider from New Zealand: Silk utilisation and predatory versatility. N.Z. J. Zool., 13: 521–541. Legendre, R. 1961. Études sur les Archaea (Aranéides). II. La capture des proies et la prise de nourriture. Bull. Soc. Zool. Fr., 86: 316– 319. Oliveira, P. S. 1988. Ant‐mimicry in some Brazilian salticid and clubi- Figs. 1–5. Predator, Corinnomma severum (Thorell 1877) and prey, onid spiders (Araneae: Salticidae, Clubionidae). Biol. J. Linn. Soc., Neoscona sp. (NSMT-Ar. 17307). 1, C. severum feeding a host spider 33: 1–15. on the prey’s web; 2, of C. severum, ventral view; 3, female Oliveira Gonzaga de, M., dos Santos, A. J. & Dutra, G. F. 1998. copulatory organ of C. severum, dorsal view: 4, habitus of prey, dorsal Web invasion and araneophagy in Peucetia tranquillini (Araneae, view; 5, same, ventral view. Scales: 0.5mm (2–3), 2.5mm (4–5). Oxyopidae). J. Arachnol., 26: 249–250. Pekár, S. & Jarab, M. 2011. Life‐history constraints in inaccurate Bate- sian myrmecomorphic spiders (Araneae: Corinnidae, Gnaphosidae). Eur. J. Entomol., 108: 255–260. Pekár, S., Coddington, J. A. & Blackledge, T. A. 2011. Evolution of Acknowledgements stenophagy in spiders (Araneae): evidence based on the compara- tive analysis of spider diets. Evolution, 66: 776–806. We thank Mr. Yu Hisasue (Kyushu University) for offering us an Platnick, N. I. 2000. A relimitation and revision of the Australasian invaluable literature and the head of Kaeng Krachan National Park and ground spider family Lamponidae (Araneae: Gnaphosoidea). Bull. staff for their support of preliminary survey following permission. Am. Mus. Nat. Hist., 245: 1–330. Whitehouse, M. E. A. 1987. “Spider Eat Spider”: The Predatory Behavior of Rhomphaea sp. from New Zealand. J. Arachnol., 15: References 355–362. Wilcox, S. R., Jackson, R. R., Gentile, K. 1996. Spiderweb smoke- Deeleman-Reinhold, C. L. 1993. A new spider genus from Thailand screens: spider trickster uses background noise to mask stalking with a unique ant-mimicking device, with description of some other movements. Anim. Behav., 51: 313–326. castianeirine spiders (Araneae: Corinnidae: Castianeirinae). Nat. Hist. Bull. Siam Soc., 40: 167–184. Received April 24, 2020/ Accepted June 16, 2020 Eberhard, W. G. 1983. Predatory behaviour of an assassin spider, Cho-

Acta Arachnologica, 69 (2), December 2020 Ⓒ Arachnological Society of Japan