The whip spider genus Sarax Simon, 1892 is widely distributed throughout Southeast Asia and part of the Indo-Malayan region. The genus is recorded from several Indonesian islands, but no species are known from inside the area that comprises the biogeographical region of Wallacea, despite being recorded from both sides of the area. An expedition to survey the biology of caves in Timor-Leste (formerly East-Timor) discovered populations of amblypygids living underground and including a remarkable new species of Sarax, S. timorensis sp. n., the first Amblypygi known from the island of Timor. The new species is here described bears the unique character state of two pairs of lateral eyes, instead of three or none as in all other living species of Amblypygi, and expands the biogeographic range of the genus. New records of amblypygids are given for two caves in Timor-Leste. A detailed description and a discussion of its distribution and the species characters are also provided.

cave, tailless whip scorpions, troglobiont, Wallacea

Southeast Asia is a global hotspot of biodiversity hitherto poorly known regarding amblypygid diversity. Among the many islands in Southeast Asian seas (Banda, Celebes, Flores, Java, Molucca, Sulu, etc.), only 15 have records of whip spiders. Recent efforts to uncover the amblypygid fauna in that region provided new species of Catageus Thorell, 1889 (Charontidae) and Sarax Simon, 1892 (Charinidae), and creation of a new genus Weygoldtia Miranda et al., 2018 (Miranda et al. 2018; Seiter and Wolff 2017; Seiter et al. 2015).

Four families of Amblypygi are known in Southeast Asia: Charontidae, Charinidae, Phrynidae, and Phrynichidae. Charinidae is the most diverse and has the widest distribution (Miranda et al. 2018). All three genera of the family (Charinus Simon, 1892, Sarax, and Weygoldtia) are present in that region, Sarax being the most diverse. Sarax species are recognized by the presence of ventral sac cover on the abdomen, presence of a seta on the lateral side of the triad of eyes and female gonopods with finger-like or sucker-like projections (Miranda et al. 2018). The genus occurs in Southeast Asia and the Indo-Malayan region, being recorded from both sides of the Wallacea shelf (on the Sunda and Sahul shelves), but never on islands inside this diverse area.

Timor-Leste (formerly East Timor) is located on the east side of Timor Island in Southeast Asia. Despite long scientific interest in the caves of Timor-Leste for the archeological sciences (O’Connor et al. 2017), almost no information is available on its diversity of subterranean-adapted species (Freire et al. 2017). Moreover, no record of amblypygids was known from the country. Recent intensive collecting in caves around the entire country provided a new view of the subterranean invertebrates of Timor-Leste, including the new species here described.

Specimens were collected by active search in caves in Timor-Leste and are deposited in the Natural History Museum of Denmark, University of Copenhagen (NHMD) in 70% ethanol. The material was analyzed under a LEICA M205 stereomicroscope attached to a camera lucida. Photographs were made using a BK plus Imaging System from Visionary Digital (Palmyra, PA, USA; http://www.visionarydigital.com) equipped with a Canon 7D digital camera. Stacks of images from multiple focal planes were combined using Zerene Stacker (Zerene Systems LLC, http://zerenesystems.com/cms/stacker) and processed in Photoshop CS6 (Adobe, San Jose, CA, USA) to adjust color, brightness, and contrast, and remove blemishes. The distribution map was produced using SimpleMappr (www.simplemappr.net).

Nomenclature generally follows Quintero (1981), while the measurements and the terminology of pedipalp and leg segments follows Harvey and West (1998). The article called the tarsus by Harvey and West (1998) is divided here into tarsus and claw, as there is no fusion of these two segments in Charinidae. The spines of the pedipalpal patella and teeth of the chelicerae are counted from the apex to the base. Measuring of the pedipalp articles was taken between the condyles of each segment in order to establish fixed points and comparable length.

Geographically close species, such as Catageus orientalis (Seiter & Wolf, 2017), Charon grayi (Gervais, 1842), Charon oenpelli Harvey & West, 1998, Charon trebax Harvey & West, 1998, Phrynus exsul Harvey, 2002 and Sarax brachydactylus Simon, 1892 were compared based on the literature (Giupponi and Miranda 2012; Harvey 2002; Harvey and West 1998; Seiter and Wolff 2017; Weygoldt 1996; 2000).

Other material examined:

Charinus pescotti Dunn, 1949: Australia, Queensland, Freshwater Creek, at Crystal Cascades, 10 km S of Freshwater [17°00'S, 145°40'E], 12.vii.1986, MS Harvey and PJ Vaughan leg. (1 male, 1 subadult male, 1 juvenile, WAM T57789); Flying Fish Point, Innisfail, 21.i.1975, RJ Raven, leg. (1 female, WAM T57787); 2 km WNW of Cape Tribulation, 23.ix–7.x.1982 (1 male, QM S38776); NeS of Pilgrim Sands, Cape Tribulation, 28.viii.1988, R Raven, T Churchill, J Gallon leg., (1 female with eggs, QM S38792); 2 km WNW of Cape Tribulation (site 2), 23.ix–7.x.1982, Monteith, Yeates and Thompson leg. (1 male, 2 females with egg sac, 9 juveniles, QM S38788); West Claudie R. (river), Iron Range, G Monteith and D Cook leg., 3–10.xii.1985, Rainforest, 50 m (2 juveniles, QM S38787)

Kronocharon longicalcaris Wunderlich, 2015: Holotype: Mid Cretaceous Burmite (1 possibly male, F2729/BU/CJW).

Sarax huberi Seiter, Wolff & Horweg, 2015: Paratypes: Republic of Philippines, Cebu: surrounding of the Busay cave [9°54'57.5"N, 123°26'13.2"E], Moalboal, iii.2008, S Huber leg. (1 female, SMNS); South of Moalbaol [9°48'20.1"N, 123°22'17.7"E], Kawasan Falls, 21.ii.2001, S Huber leg. (1 female, 1 male SMNS). Non-type: East slope Mt McKinley, Davao Prov., Mindanao, 26.ix.1946, FG Werner leg., Philippine Zool. Exped. 1946-7, 3300 ft. asl., in tall stump (1 female, 1 juvenile, FMNH 3489489); East slope Mt McKinley, Davao Prov., Mindanao, 10.x.1946, FG Werner leg., Philippine Zool. Exped. 1946-7, 3000 ft. asl., debris on agricultural land (1 male, 1 juvenile, FMNH 3489491); East slope Mt McKinley, Davao Prov., Mindanao, 14.viii.1946, H Hoogstraal leg., Philippine Zool. Exped. 1946-7, 4000 ft. asl., forest floor (1 female, 1 juvenile, FMNH 3489498).

Sarax sarawakensis (Thorell, 1888): Indonesia: Bali, Candidasa, Tenagan [8°28'16.2"S, 115°34'8.4"E], 17.iii.2009, S Huber leg. (1 male, AMNH LP 11594); Nusa Tenggara Barat, Sumbawa, Batoedoelang, Sunda Exped., 1927, Rensch leg. (SMF 17.393); no further information (CUMZ I.46520).

Sarax willeyi Gravely, 1915: Papua New Guinea: New Britain: S. küst, Hamburg. Südsee Exped., 5–8.ii.1909, G Duncker leg. (1 male and 6 juveniles, ZMUH); Ralum, 21.x.1896, Dahl L leg. [abdomen detached from the body] (1 female, ZMUH).

Sarax yayukae Rahmadi, Harvey & Kojima, 2010: Malaysia: Sarawak: Kuching, Mjóhesg leg., GS Miranda det. (1 female, 1 male, AMNH Ambly 87); Racer Cave [04°03'25.9"N, 114°49'36.8"E], Gunung Mulu National Park, 2–3.viii.2013, 34 m asl., L. Qie, J. Huff, L. Kumpang, M Peter and A Ang leg., GS Miranda det. (3 female, 3 males, 3 juveniles, AMNH LP 12152). Malaysia: Sabah: Pulau Gaya [06°00'44.8"N, 116°00'34.8"E], Tunku Abdul Rahman National Park, 25–28.7.2013, 2 m asl., SF Loria and J Huff leg., GS Miranda det. (5 females, 5 males, 4 juveniles, AMNH LP 12109); Sandakan: British N. Borneo, 8.vii.1929, KP Schmidt leg. (1 male, FMNH 3489490);

Weygoldtia davidovi (Fage, 1946): Syntypes: Vietnam (as Annam): PhanRang, iii–iv.1939, Mission Dawydoff, 1938–39, (3 males, MNHN); Ba Ngoi [11°54'27.23"N, 109°7'21.37"E], x.1938, Mission Dawydoff, 1938–39, Indochine (2 females, plus 1 specimen MNHN); GiaRai (as Giaray) [09°15'36.51"N, 105°22'31.11"E], Bac Liêu, xii.1938–iii.1939, Mission Dawydoff, 1938–39, Indochine (2 males and 3 juveniles, MNHN); Sóc Traeng [09°36'9.01"N, 105°58'25.95"E], Sóc Traeng, xi.1938, Mission Dawydoff, 1938–39, Indochine (1 male, MNHN). Laos: Pak Lay [18°13'50.03"N, 101°24'30.12"E], Xiangnabouli, i.1939, Mission Dawydoff, 1938–39, Indochine (1 juvenile, MNHN). Cambodia: Ream [10°35'2.75"N, 103°38'35.34"E], iii.1939, Mission Dawydoff, 1938–39, Indochine (1 female, 2 juveniles, MNHN).

Acronyms:

AMNHAmerican Museum of Natural History, New York (Lorenzo Prendini);

CJW Collection of Joerg Wunderlich (Joerg Wunderlich);

CUMZCambridge University Museum of Zoology, UK (Matt Lowe);

FMNHThe Field Museum of Natural History, Chicago (Petra Sierwald);

MNHNMuséum national d’Histoire naturelle, Paris (Mark Judson);

NHMD Natural History Museum of Denmark, University of Copenhagen (Nikolaj Scharff);

QMQueensland Museum, Brisbane (Robert Raven);

SMFSenckenberg Museum für Naturkunde, Frankfurt (Peter Jäger);

SMNSStaatliches Museum für Naturkunde, Stuttgart (Joachim Holstein);

WAMWestern Australian Museum, Perth (Mark Harvey);

ZMBZoologisches Museum Berlin (Jason Dunlop);

ZMUHZoologisches Museum für Hamburg, Hamburg (Matthias Glaubrecht).

Amblypygids of the family Charinidae have, in general, a uniform morphology, but variation is found in several small characters. The number of spines on the pedipalp, for example, varies in distantly related species; the number of teeth on the chelicera also tend to be unique to the different species groups; the same occurs with the position and number of trichobothria on the legs and the number of articles on the first pair of legs and the shape of the female and male genitalia (Giupponi and Miranda 2016; Miranda et al. 2018; Miranda et al. 2016; Weygoldt 2000). Remarkably, some species even lack the median and/or lateral eyes, such as in C. aguayoi Moyá-Guzmán, 2009, C. bichuetteae Giupponi & Miranda, 2016, C. bonaldoi Giupponi & Miranda, 2016, C. caribensis (Quintero, 1986), C. dominicanus Armas & González, 2001, C. guto Giupponi & Miranda, 2016, C. muchmorei Armas & Teruel, 1997, C. reddelli Miranda, Giupponi & Wizen, 2016, C. troglobius Baptista & Giupponi, 2002, and C. vulgaris Miranda & Giupponi, 2011, among others. The complete absence of eyes in charinid whip spiders is even rarer and is known only in Charinus bordoni (Ravelo, 1977) and Charinus stygochthobius Weygoldt & van Damme, 2004. In other amblypygid families, this character state occurs in the paracharontid species Paracharon caecus Hansen, 1921 and the phrynid species Paraphrynus reddelli Mullinex, 1979.

Sarax species lacking eyes are unknown and there is no record of a living species with a different disposition of ocelli than the usual two median plus three lateral pairs, or no median and three lateral pairs or no eyes at all. A distinct eye arrangement, however, is known in extinct taxa. Some species of the genera Kronocharon Engel & Grimaldi, 2014 and Paracharonopsis Engel & Grimaldi, 2014 have two pairs of lateral eyes, similar to S. timorensis sp. n.; they are K. longicalcaris and P. cambayensis, respectively. The first is from Burmese amber from ca. 100 million years ago (mya) and belongs to the Unidistitarsata clade; the second is an Indian amber inclusion from ca. 56 mya which is nested within Paracharon in Paracharontidae (Engel and Grimaldi 2014; Garwood et al. 2017). The two-lateral-eyes arrangement present in the three species could be a plesiomorphic character state shared among three distinct branches in the Amblypygi tree; another hypothesis is that the species evolved the character state independently as result of pressure from the environment they inhabit or used to inhabit.

Subterranean arthropods tend to have the troglomorphy syndrome, consisting of eye and pigment degeneration, combined with hypertrophy of appendages and sensorial organs, and changes in their metabolism and reproduction. This happens as a result of selective environmental pressures typical of the aphotic and oligotrophic subterranean ecosystem (Culver and Pipan 2014). Sarax timorensis sp. n. does not exhibit highly troglomorphic traits, yet this is one of the largest species in Charinidae, and the tendency to gigantism is also marked in caves as it happens in islands. The largest described species in the family is Sarax cavernicola Rahmadi, Harvey & Kojima, 2010 from Indonesia (East Kalimantan), with carapace length ranging between 4.57–6.37 mm and carapace width from 6.30 to 8.29 mm, femur length with 5.95–8.98 mm and patella length measuring 6.15–9.08 mm (Rahmadi et al. 2010). The new species S. timorensis becomes the second largest followed by Weygoldtia davidovi (Fage, 1946) from Vietnam. All these species inhabit tropical forests in Southeast Asia. The precise habitat of K. longicalcaris and P. cambayensis is unknown, but the preservation of the specimens suggest that they lived in a forested area, so troglomorphic pressures likely do not apply in their cases.

The closest geographical amblypygid species to Sarax timorensis sp. n. are Phrynus exsul Harvey, 2002 found in caves on Flores Island, Indonesia (Harvey 2002), Charon grayi (Gervais, 1842), Charon oenpelli Harvey & West, 1998, and Catageus orientalis (Seiter & Wolff, 2017) found in the surrounding islands and in Australia (Harvey and West 1998; Seiter and Wolff 2017). The closest Sarax species is likely to be Sarax willeyi Gravely, 1915 from West Papua Province in Indonesia (Giupponi and Miranda 2012), located 899.5 km away. Papua-New Guinea and West Papua are part of the Sahul shelf and bear two species of Sarax. Almost all other records of the genus are recorded from the Sunda shelf, another Southeast Asian biogeographic region. Nevertheless, the Wallacea shelf, which is the intermediate zone between Asia and Oceania, had no records of the genus so far. The discovery of a Sarax species in Wallacea fills a gap in the distribution of the group and poses doubts on the effects of the Lydekker and Wallace’s lines on the distribution of whip spiders in Southeast Asia. Future works will address these biogeographic questions within amblypygids.

Amblypygids in Southeast Asia are still poorly known regarding their systematics, distribution, and biology. Almost 100 records are known for the order in the area and several islands remain without published records for whip spiders. Therefore, it is expected that more species will be found across the region.

We are grateful to the members of the Fatuk-Kuak hosi Timor-Leste Expedition and to the Juventude Hadomi Natureza for all their support during the fieldwork. To the Universidade Nacional de Timor Lorosa’e (UNTL), Geiza Oliveira, the Fundação Oriente (Díli Delegation), and to the Portuguese Embassy in Díli, grateful acknowledgements for all the logistic support in Timor-Leste. We would also like to thank Nikolaj Scharff for laboratory facilities, and Michael Seiter and Mark Harvey for reviewing the manuscript. All specimens were collected under the permit established in the collaboration protocol between the UNTL and the Núcleo de Espeleologia da Universidade de Aveiro. GSM is thankful to the Peter Buck Postdoctoral Fellowship and the Smithsonian Institution. This work was supported by a research grant (15471) from the VILLUM FONDEN.