Arachnologische Mitteilungen 58

10 C. Bartel & J. A. Dunlop forest ecosystem has been inferred, dominated by an extre- mely warm and humid climate cumulating in the so-called Eocene Optimum at ca. 49 Ma. Several animal groups usually associated with warmer climates, of which laniatorid harvest- men are one example, are thus present in Baltic amber even though they are no longer present in north-central Europe today. Possible source trees for the resin which formed Baltic amber are araucarians, cedars or umbrella pines. Taxonomy Order Opiliones Sundevall, 1833 Suborder Laniatores Thorell, 1876 Family Cladonychiidae Hadži, 1935 Proholoscotolemon nemastomoides (Koch & Berendt, 1854) (Fig. 1a-c) Material. CJW BBF2568, from Baltic amber (Eocene: Lu- tetian). Description. Body pear-shaped, slightly granulated espe- cially posteriorly; length (including free tergites) 2.27, proso- ma width 1.32, opisthosoma width 1.82. Ocularium low and oval (length 0.27, width 0.41) with median eyes centrally on the prosoma. Chelicerae relatively long and robust; proximal segment length 0.59*, hand equivocal. Pedipalps raptorial with several long, thick spines. Trochanter with single ven- tral spine; femur with three dorsal, two mesal and four ectal spines; patella with two mesal spines; tibia with four pairs of lateral spines (from base to apex: two long, two short); tarsus with three pairs of lateral spines (from base to apex: two long, one short). Pedipalp claw shorter than tarsus and slightly curved. Pedipalp article lengths: trochanter 0.43, femur 0.91, patella 0.64, tibia 0.68, tarsus 0.64, claw 0.41; total (trochan- ter–tarsus) 3.48. Legs elongate (leg II longest) and smooth. Tarsi subdi- vided into tarsomeres; terminating in one claw on tarsi I–II and two claws with a single insertion on tarsi III–IV (Fig. 1b: inset). Tarsal claws III–IV smooth, with relatively long base and widely separated prongs. Tarsal formula (i.e. tarsomere counts) 4:11:6:8. Leg I trochanter 0.20, femur 0.86, patella 0.45, tibia 0.95, metatarsus 0.95*, tarsus 0.82; total (trochan- ter–tarsus) 4.23. Leg II trochanter 0.36, femur 1.84, patella 0.50, tibia 1.50*, metatarsus 1.66, tarsus 1.86; total (trochan- ter–tarsus) 7.72. Leg III trochanter 0.27, femur 1.14, patella 0.54, tibia 1.00, metatarsus 1.04*, tarsus 0.82; total (trochan- ter–tarsus) 4.81. Leg IV trochanter 0.32, femur 1.23, patella 0.54, tibia 1.14, metatarsus 1.82, tarsus 1.14; total (trochan- ter–tarsus) 6.51. Ventral region equivocal; completely covered with white emulsion. Remarks. CJW BB F2568 is evidently an adult laniatorid due to the presence of large, strongly spined pedipalps and its high tarsomere count. It closely resembles the known Baltic amber species Proholoscotolemon nemastomoides , redescribed by Ubick & Dunlop (2005), particularly in terms of the number and position of the pedipalp spines and the observed claw pattern: smooth tarsal claws of legs III–IV with widely se- parated prongs and a relatively long base (Fig 1b: inset). Our new fossil has a slightly higher tarsomere count compared to previously described material, but on other characters CJW BB F2568 can be referred with some confidence to P. nema­ stomoides . Koch & Berendt (1854) originally assigned the Baltic am- ber species to the Neotropical genus Gonyleptes Kirby, 1819 which belongs to the infraorder Grassatores.This makes little biogeographical sense; although in fairness Gonyleptes was the first living laniatorid genus to be described and there were relatively few genera known in the mid-nineteenth century. The Y-shaped claw on tarsi III–IV of at least the adult fossils clearly supports their referral to the other infraorder: Insidi- atores. The habitus of the amber fossils is very similar to the extant Holoscotolemon Roewer, 1915 and Proholoscotolemon ne­ mastomoides has been proposed as the sister-group, or perhaps even ancestral, to this modern southern European genus. Re- garding familial placement, Ubick & Dunlop (2005) transfer- red P. nemastomoides to Cladonychiidae.This family was sub- sequently downgraded to a subfamily of Travuniidae by Kury et al. (2014), but recent revision by Derkarabetian et al. (2018) accepted Cladonychiidae as a valid family group name and explicitly listed the Baltic amber genus within it.The position of the low ocularium, the long and robust chelicerae, the hea- vily spined pedipalps and the shape of tarsal claws III-IV in the fossils are all consistent with cladonychiids. Other fami- lies of Insidiatores often bear complex claws on tarsi III–IV Fig. 1: Proholoscotolemon nemastomoides (Koch & Berendt, 1854, CJW BB F2568): a. dorsal overview; b. camera lucida drawing; (inset: detail of claws on tarsus III showing the single insertion); c. close-up of the pedipalps in ventral view. Abbreviations: ch – chelicerae, cl – claw, fe – femur, oc – ocularium, pa – patella, pp – pedipalp, ta – tarsus, ti – tibia. Legs numbered from I–IV. Scale bars 1 mm (inset of b: 0.2 mm)