BIODIVERSITAS ISSN: 1412-033X Volume 23, Number 8, August 2022 E-ISSN: 2085-4722 Pages: 4283-4288 DOI: 10.13057/biodiv/d230852 Short Communication: A new species of tarantula of the genus Orphnaecus Simon, 1892 (Araneae: Theraphosidae) from the Province of Dinagat Islands, Philippines JULIUS JOHN DP. SALAMANES 1, , JHAYSON MARK J. SANTOS 1 , ELEANOR S. AUSTRIA 1 , GIL GABRIEL S. VILLANCIO 1,2 1 Biology Department, College of Science, Adamson University. 900 San Marcelino St. Ermita, 1000 Manila, Philippines. Tel./fax.: +63-9612142318,  email: julius.john.salamanes@adamson.edu.ph 2 School of Environmental Science and Management, University of the Philippines. Los Banos, Laguna, Philippines Manuscript received: 6 June 2022. Revision accepted: 2 August 2022. Abstract. Salamanes JJDP, Santos JMJ, Austria ES, Villancio GGS. 2022. Short Communication: A new species of tarantula of the genus Orphnaecus Simon, 1892 (Araneae: Theraphosidae) from the Province of Dinagat Islands, Philippines. Biodiversitas 23: 4283- 4288. Orphnaecus adamsoni sp. nov., a new species of tarantula of the genus Orphnaecus Simon, 1892 is described and illustrated based on the specimens collected from the Province of Dinagat Islands, Philippines. It closely resembles O. kwebaburdeos (Barrion- Dupo, Barrion & Rasalan, 2015). However, it can be easily distinguished by having a rounded carapace, shorter leg segments, more clavate-paddle shaped maxillary lyra, and a different habitat. This mygalomorph spider discovery constitutes the fifth species described for Orphnaecus and the fourth record in the Philippines. Keywords: Araneae, mygalomorph, Province of Dinagat Islands, tarantula, taxonomy INTRODUCTION The Philippines is regarded as one of the world's biodiversity hotspots in terms of high species richness and endemism (Myers et al. 2000). Despite this, the Philippines accounts for less than 2% of all recognized tarantula species (Barrion-Dupo et al. 2015). These mygalomorphs are medium to large-sized, often hairy spiders that live in silk-lined burrows on the ground (Foelix 2011). Tarantulas are members of the speciose Theraphosidae family, which includes 970 species in over 130 genera and is mostly found in tropical and subtropical regions (World Catalog Spider 2017). In the Philippines, only 11 Theraphosidae species have been identified: Melognathus dromeus Chamberlin, 1917 (Chamberlin 1917; Smith 1987; Schmidt 2003; Gabriel and Sherwood 2019); Orphnaecus kwebaburdeos Barrion-Dupo, Barrion & Rasalan, 2015 (Barrion-Dupo et al. 2015; Nunn et al. 2016); O. pellitus Simon, 1892 (Simon 1892; West et al. 2012); O. philippinus Schmidt, 1999 (Schmidt 1999; West et al. 2012); Phlogiellus baeri Simon, 1877 (Simon 1877; West et al. 2012; Nunn et al. 2016); P. bundokalbo Barrion & Litsinger, 1995 (Barrion and Litsinger 1995; Schmidt 2010); P. insularis Simon, 1877 (Simon 1877; Nunn et al. 2016); P. johnreylazoi Nunn, West & von Wirth, 2016 (Nunn et al. 2016); P. mutus Giltay, 1935 (Giltay 1935; Schmidt 2010); Selenocosmia peerboomi Schmidt, 1999 (Schmidt 1999) and S. samarae Giltay, 1935 (Giltay 1935; Schmidt 1999). This figure may not accurately reflect the true diversity of Philippine tarantulas because these spiders are understudied in the country. The recognized gap, as well as the threat of destructive anthropological activities such as deforestation and poaching, necessitates additional research and conservation. Genus Orphnaecus was described by Eugène Louis Simon in 1892 with the type species was O. pellitus Simon, 1892 discovered in Calapnitan Caves in Camarines Sur Province, Philippines. By West et al. 2012, this genus was considered a senior synonym of Chilocosmia Schmidt and von Wirth, 1992 and of Selenobrachys Schmidt, 1999. Currently, there are four recognized Orphnaecus species (Table 1), three of which are restricted to the Philippines; however, it is believed that there are numerous unidentified species (Nunn et al. 2016). The recently discovered Orphnaecus species from Burdeos, Polilio Island in Quezon Province, O. kwebaburdeos was originally described as Phlogiellus kwebaburdeos but was transferred to the genus Orphnaecus by Nunn et al. 2016 due to the presence of three long and three short clavate paddle- shaped setae and >250 spiniform setae that are absent in the lyrate arrangement of Phlogiellus as well as the color difference in situ of the genus. A cryptic Theraphosidae species was collected as part of a floral and faunal diversity assessment in the unexplored province of Dinagat Islands in the Philippines. In this study, the morphological characteristics of the collected tarantula species were compared to the four identified Orphnaecus species. We found no similarities with the existing species, so a new Orphnaecus species is hereby described.