A new species of Lacinius in amber ( Arachnida : Opiliones ) 39

A new specimen of LaciniusThorell, 1876; (Opiliones: Phalangiidae) from Eocene Baltic amber is described. We interpret it as conspecific with a slightly younger record from the German Bitterfeld amber, originally referred to as the extant species L. erinaceusStaręga, 1966. Our new specimen reveals pedipalpal apophyses on both the patella and the tibia, features which we can now confirm in the Bitterfeld fossil too. This unique character combination for the genus justifies a new, extinct species: Lacinius bizleyisp. nov. The Baltic amber inclusion dates to ca. 44–49 Ma, and is thus the oldest putative example of Laciniusin the fossil record. It is a further example of an arachnid species shared between Baltic and Bitterfeld amber.


Introduction
Harvestmen in the genus Lacinius (Opiliones: Phalangiidae) Thorell, 1876 are typically characterized by a distinctive spiny ornament across the legs and body.Lacinius is currently represented by seven Recent species (Table 1), six of which are found in central Europe down into the Balkans and the Mediterranean, as well as in northern Africa, Turkey and the Caucasus (e.g.Kraus, 1961;Šilhavý, 1956, 1965;Staręga, 1966Staręga, , 1976;;Marcellino, 1975;Martens, 1978;Prieto, 2003Prieto, , 2008;;Novak, 2005;Çorak et al., 2008, 2014;Sánchez-Cuenca and Prieto, 2014).Additionally, one species is recognized from the USA (Banks, 1893), while a further putative American Lacinius was synonymized with a species in Odiellus Roewer, 1923 by Cokendolpher and Lee (1993).Note that the online species lists assembled by Hallan (2005) did not always include all published synonyms, compared with Crawford (1992).Over-reliance on such online data for harvestman taxonomy -and the resulting risk of errors being copied and multiplied into other publications or resourceswas recently critiqued by Schönhofer (2013).Similarly, the Lacinius species from China listed in Hallan (2005), Lacinius bidens (Simon, 1880) (Acantholophus bidens; Simon, 1880), has long been referred to as Bidentolophus Roewer, 1912 (see Roewer, 1912Roewer, , 1923;;Wang, 1953;Li and Song, 1993), which is a junior subjective synonym of Lacinius Thorell, 1876 (see Crawford, 1992: p. 13).Note also that the Spanish species L. carpetanus (Rambla, 1959) was recently transferred to Odiellus by Sánchez-Cuenca and Prieto (2014).As shown in Table 1, three of the six Recent Palearctic species are fairly widely distributed across Europe (often through into Turkey).Others are more restricted and local in their ranges.

Material and methods
The new specimen from Baltic amber was acquired by one of us (D.Penney) via Jonas Damzen (Vilnius).It has now been deposited in the amber collection of the Museum für Naturkunde (MfN) Berlin under repository number MB.A. 2815 for "Museum Berlin, Arthropoda".It was drawn under a Leica MZ12.5 stereomicroscope with a camera lucida attachment and photographed immersed in water on a Leica Z16 microscope running the Leica Application Suite software package for generating stacks of images in different focal planes.These were combined into final pictures using Helicon Focus and edited in Adobe Photoshop.All measurements in the descriptions are in millimetres.
The new fossil was compared to the previous amber Lacinius specimen, again in the MfN under repository number MB.A 1661.We also examined alcohol-preserved specimens (adults and juveniles) of recent Lacinius species and other phalangiid harvestmen in the zoological collections of the MfN, as well as material from the private collection of P. G. Mitov.These were compared with published descriptions from the literature (e.g.Roewer, 1923).We also consulted images of living species kindly provided by Christian Komposch (Graz) -see also Fig. 3 -and Nataly Snegovaya (Baku).Type locality and horizon.From Bitterfeld amber, Saxony-Anhalt, Germany.Palaeogene (?Oligocene).Described in detail by Dunlop and Mitov (2009).
Additional material.MB.A. 2815 (ex D. Penney coll., via J. Damzen).Baltic amber; precise locality not recorded, but most of the recently acquired material stems from the Kaliningrad region of the Russian Baltic coast.Palaeogene (Eocene: Lutetian).
Derivation of name.In honour of the British palaeoartist Richard Bizley (Lyme Regis) for his assistance to D. Penney with various palaeontology-related projects.
Diagnosis.Species of Lacinius with a combination of ornamented body and leg articles (except tarsi) with numerous long sharp-pointed/tipped thorns, and distinct apophyses on both the patella and tibia of the pedipalp; patellar apophysis longer than tibial apophysis.
Description of MB.A. 2815.Relatively complete specimen (right leg II mostly missing), best seen in dorso-lateral view (Figs.1-2).Body oval, flattened, length ca.1.2 mm; maximum width of prosoma ca.1.0 mm, of opisthosoma ca.0.9 mm.Ocularium raised and ornamented with at least five curving thorns (whereby thorns here have a thick base and then taper about midway along their length into a sharp spine); ocularium length and width ca.0.14 and 0.23 mm respectively, distance from front of carapace ca.0.2 mm.Distinct pattern of triad of forward-projecting spines immediately in front of ocularium (Figs.1a, 2b).Opisthosoma, particularly the posterior portion, ornamented with numerous backwards-pointing thorns, each consisting of a thicker base with a short, stiff seta at the tip.Chelicerae equivocal.Pedipalps with distinct apophyses projecting from both patella and tibia (Figs.1a, 2b).Palpal femur disto-medial with one setose, apophysis-like protrusion.Patellar apophysis long, somewhat spatulate -almost reaching length of tibia -and highly setose on its mesal surface as well as apophysis tip.Tibial apophysis short and blunt, projecting mesally and again bearing numerous setae.Legs moderately long, leg II markedly longer than others (leg formula from longest to shortest: II, IV, III, I); approximate total lengths: I, 2.0 mm; II, 6.0 mm; III, 2.4 mm; IV, 3.2 mm.Trochanter, femur, patella and tibia of all legs more robust, again with distinct arrangement of thorns topped with stiff setae, arranged in discrete rows along length of limb article.Tibia to tarsus more slender.Basal part of the tibia with two robust thorns; distal portion of the legs otherwise with stiff setae only.Metatarsi dorsally bear short thorns and strong setae.Tarsi subdivided into ca.seven tarsomeres in each leg where visible (exact number equivocal on some legs); proximal and distal-most tarsomeres longer than those in between.All legs end, where preserved, in a single, curved claw.Genital characters could not be resolved.
Discussion.The new Baltic amber fossil is similar in habitus to the previous record from Bitterfeld, which Dunlop and Mitov (2009, Figs. 27, 31-32) tentatively assigned to Lacinius erinaceus.In the present study, we also considered a similar-looking, spiny harvestman genus: Homolophus Banks, 1893.For details of this taxon, see e.g.published descriptions of H. afghanus (Roewer, 1956), H. chitralensis (Roewer, 1956), H. trinkleri (Roewer, 1956) and H. turcicus (Roewer, 1959).Note that Roewer (1956Roewer ( , 1959) ) originally described these species under Euphalangium; for a generic synonymy, see Cokendolpher (1987).We also consulted Snegovaya's recent (2012) description of Homolophus nakhichevanicus Snegovaya, 2012.We believe that we can exclude the amber inclusions from Homolophus based on the presence in the fossils of a triad of spines at the front of the carapace (Figs.1b, 2b) and the additional presence of spines on the metatarsi of the legs (Fig. 2a).In many Homolophus species, there are two principal, diverging forward-pointing spines -or "Gabelzähnchen" -at the front of the carapace, surrounded by a group of denticles sometimes forming a crown.The remaining Homolophus species only have a group of frontal denticles.Furthermore, the metatarsi of the legs of Homolophus are normally smoother than the spiny metatarsi seen in the amber specimens; only some Homolophus species have denticles/tubercles ventrally.
The closest potential match would be the North American species L. texanus Banks, 1893, for which Banks (1893, p. 403) stated that "The patella is prolonged, the inner side and prolongation being covered with short, stiff, black hairs.The tibia is enlarged at the end on the inner side and covered with similar hairs [...]".Unfortunately there is no illustration in the original description to show whether Bank's "prolongation" of the patella is a substantial apophysis as per the fossil specimens, but subsequent figures and/or redescriptions of L. texanus by Banks (1901, Fig. 4) and later Roewer (1912, p. 81;1923, p. 743) do not indicate explicit pedipalpal apophyses.As noted above, the general habitus of L. texanus is also less spiny than our amber material, which argues against the fossils being closely related to the living American species.
On balance, we feel justified in proposing a new (fossil) Lacinius species diagnosed on the combination of body ornamentation and pedipalp morphology as above.As noted previously, the new specimen is quite small, and the individual may be immature.Where apophyses are present in phalangiid harvestmen, they can be more prominent in immature instars and become less well expressed in adults.We select the first specimen to be described (MB.A. 1661 from Bitterfeld amber) as the holotype of our new taxon.Since the second (Baltic) specimen is not from the same locality as the holotype, we chose not to treat it as a paratype.The Baltic example of Lacinius bizleyi sp.nov.places the genus back at least in the Eocene, and can also be added to the list of harvestmen found in both Baltic and Bitterfeld amber.The other harvestmen common to both ambers are the nemastomatid Histricostoma tuberculatum (Koch and Berendt, 1854), the caddid Caddo dentipalpus (Koch and Berendt, 1854), the phalangiid Dicranopalpus ramiger (Koch and Berendt, 1854) and the sclerosomatid Leiobunum longipes Menge, 1854.The Opiliones data thus remain preliminary, but our new fossil contributes to the debate (reviewed by, e.g., Standke, 2008, andDunlop, 2010) about whether Baltic and Bitterfeld ambers are in fact contemporary deposits, sampling the same (implicitly Eocene) fauna.Alternatively, if Bitterfeld amber is a distinct and younger deposit -and not merely older Baltic amber reworked into younger sediments -it implies that there was something of a faunal continuum in the Paleogene of northern-central Europe.In other words, the same (morpho)species of harvestmen, and probably other arachnids too, can be found in the fossil record of this region of Europe across an Eocene-to-Oligocene time period which may correspond to about 25 million years.

Figure 2 .
Figure 2. Camera lucida drawings of the specimen shown in Fig. 1.(a) Overview.(b) Detail of the anterior prosoma.Legs numbered from I to IV.

Table 1 .
Summary of the seven living and one fossil ( †) species belonging to the harvestman genus Lacinius (Phalangiidae; Thorell, 1876) currently recognized in the literature.