Materials and Methods In late September 2014, one of us (WH) discovered a large, extremely colorful, but unrecognized female spider in an expansive web spun between upper tree branches about 2.5 m above-ground at a site in Madison County (Colbert), Georgia. The spider’s identity was confirmed (by ERH) using taxonomic references on Asian spiders (cited herein), examining and comparing the male genital structures (palpal organ) with that illustrated in the primary literature, and by comparing specimens in hand with images posted on the Internet for this common eastern Palearctic species. This remarkable discovery prompted us to find a way to determine if other people in northeast Georgia had encountered this large, attractive orb-weaving spider. Almost as soon as a press release appeared in a local newspaper in late October—calling attention to the first-time detection of this spider in North America with a color image—we heard almost immediately from several concerned citizens throughout a three-county area of northeast Georgia (Lee, 2014). Over the course of the next week to 10-days, we had confirmed sightings from at least 9 locations (see locality data under North American records). With the exception of only a few sightings, we were able to collect specimens (females) from all locations. On one occasion at a small community park (Braselton Park) in Braselton, Georgia (November 4), we (ERH and BJF) collected specimens (2 females, 2 males) in webs around the perimeter of a tennis court and along the wooded edge of the park. These are the only 2 males we have found to date. A genetic analysis (by BJF) involved the sequencing of 2 female specimens from Jackson (GMNHTC 12242) and Madison (GMNHTC 12241) counties. Genomic DNA was extracted from single spider legs previously preserved in 95% ethanol, using a Chelex® 100 Resin and proteinase-k solution, incubated overnite at 55 °C (Casquet, Thebaud & Gillespie, 2012). The cytochrome C oxidase subunit I (COI) mitochondrial gene was amplified by polymerase chain reaction (PCR) using the primer combinations of LCO1490: 5′-GGTCAACAAATCATAAAGATATATTGG-3’ and HCO2198: 5′-TAAACTTCAGGGTGACCAAAAAAATCA-3′ (Folmer et al., 1994; Su et al., 2011), and recovered a 639 base pair fragment with a starting motif of TTGGTACTGCAATAAGAGTA. PCR reactions followed conditions reported in Wares, Gaines & Cunningham (2001). PCR products were assayed by electrophoresis using a 1.0% agarose gel and sequencing was performed by Macrogen (Macrogen, USA; available at https://www.macrogenusa.com/). Sequence files were aligned using CodonCode Aligner, and Geneious version 8.05 (created by Biomatters, available at http://www.geneious.com/) was used to visualize sequence data and compared with published sequences for Nephilidae. Voucher specimens of N. clavata are deposited in the Collection of Arthropods, Georgia Museum of Natural History (UGCA), and specimens sequenced are also catalogued in the Georgia Museum of Natural History Genomic Collection (GMNHTC) University of Georgia, Athens, Georgia. In addition, an ArcGIS map of collection locations of N. clavata in northeast Georgia is provided.

Discussion Hundreds of non-native species of animals and plants have been inadvertently introduced into managed landscapes and natural ecosystems of North America. In fact, an estimated 2,000+ species of insects and arachnids have become established in North America over the past half-century and are largely attributable to a dramatic increase in travel and international commerce (OTA, 1993). To date, approximately 60 species of non-native spiders (Araneae) have been detected in North America, with the majority originating from Europe and Asia (a species list of adventive spiders in North America is posted at http://bugguide.net/node/view/32329#Anchor_Araneae). Nephila clavata becomes the newest species to be added to this list of non-native spiders occurring in North America. Potential pathways of introduction. Accidental human transport of spiders and their egg masses on or within cargo containers, on plant nursery stock and on crates and pallets (Nentwig & Kobelt, 2010), can explain and account for the presence of many European and Asian species in North America. We think this is the probable means of transport by which N. clavata gained entry. If accidental transport of N. clavata were to occur in late August to early October from countries of origin in East Asia, then the spiders’ reproduction would be at its height and there would be a greater likelihood that egg sacs might be deposited on structures or plant material being exported. Country of origin. Sequence data for the COI gene recovered from these Georgia specimens confirms our identity of N. clavata by comparison with published sequences from nine different Asian populations of N. clavata, and suggests that specimens recorded from Georgia are more closely related to sources in China or Japan, rather than Taiwan, based on the unique haplotypes. The Georgia specimens sequenced span the geographical range of our records, suggesting that they share the same source. The Yunan (HQ441928) and Huaining (KJ577713) China specimens are over 1,500 km distant from each other, and the Saitama, Japan population (HQ441929) is over 4,000 km from Yunan, and all of these sequences are identical for about 700 base pairs of COI and share the same variable haplotypes as the Georgia specimens. Specimens from Xiaguan, China (KC849082), Kaohsiung, Taiwan (HQ441927), and unspecified Asian locations (AY052586, JN032336, JN817136, and AB917973) share a different set of variable haplotypes from the Georgia specimens, and also span a similarly broad geographic range. Dispersal opportunities. Once spider populations have successfully colonized in a given location, individual spider movement might be best explained by the movement of transport vehicles along major rail or road corridors (Nentwig & Kobelt, 2010) or possibly by ballooning of spiderlings in the spring after egg hatch. Ballooning is a behavior by which spiders use air-borne dispersal to move between locations. Depending on mass and posture, a spider might be taken up into upper air streams (Suter, 1992), while its aerial movement would be dependent on convection air currents and on the drag of the silk parachute (Greenstone, Morgan & Hultsh, 1987). Members of the genus Nephila have been suggested by some (Kuntner & Agnarsson, 2011; Su et al., 2011) to be among the best spider dispersers via their ballooning behavior. A preponderance of sightings and collection of specimens of N. clavata were centered on a restricted area in and around Braselton and Hoschton, Georgia. One property owner in Hoschton indicated that the spider had been present around her home for at the past 4 years. We are not necessarily suggesting that this area represents the probable arrival point of this Asian spider, but it could be argued that the industrial and business history of the region might demonstrate it to be a possibility. The town of Braselton is a thriving business location on the I-85 business corridor, located 64 km northeast of Atlanta. As such, its location on the I-85 corridor provides excellent transportation access. It is home to many warehousing and distribution facilities that transport containerized freight from overseas. Collection locales in Jackson and Barrow counties (n = 7) are clustered on the I-85 corridor but the Madison county records (n = 2) are located in a rural mixed farm landscape, not adjacent to commercial transportation corridors. The Madison county sites are ca. 50 km due west and downwind from the other Barrow and Jackson county sites. We hypothesize that these downwind sites were colonized by aerial dispersing spiderlings using the prevailing westerly winds and suggest that other populations might be found along this route.