New record for the genus Platymessa Mello-Leitão, 1941 in Colombia, with the description of a new species (Opiliones, Cosmetidae)

Abstract The genus Platymessa Mello-Leitão, 1941 is represented by two species in the Andes of Colombia: P. h-inscriptum Mello-Leitão, 1941 and P. ectroxantha Mello-Leitão, 1941. Platymessa victoriae Pinzón-M. & Townsend, sp. n. is described on the basis of somatic morphological characters and the structure of the penis. The placement of this new species in the genus Platymessa is based upon multiple characters including the outline of dorsal scutum, the presence of a blunt spine on coxa IV, having short and strong legs with femora III and IV having five longitudinal rows of small tubercles, the shape of the basitarsomeres of male leg I, the distribution and relative sizes of the marginal setae on the ventral plate of the penis, and the morphology of the chelicerae and cheliceral sockets. In contrast to other members of the genus, P. victoriae has a pair of triangular tubercles on scutal area III, lacks paired paramedian tubercles on scutal area V, and does not have a ladder mask color pattern on the dorsal scutum. The description of this species expands the distribution of the genus to north of the Oriental Cordillera in the Cesar Department of Colombia.


Introduction
The family Cosmetidae Koch, 1839 is distributed from the southern U.S. to Argentina and with over 700 species, it is the second largest family of harvestman in the suborder Laniatores (Medrano and Kury 2016). Cosmetid harvestmen also are one of the best represented families of laniatorean harvestmen in the Neotropics (Kury and Pinto-da-Rocha 2007). The major distinguishing feature of cosmetid harvestmen is the lateral compression of the tibiae of the pedipalps that partially cover the chelicerae at rest (Pinto-da-Rocha 2011). The genus Platymessa Mello-Leitão, 1941 was originally diagnosed using characters based upon the Roewerian system, including the morphology of tarsus I and the ornamentation of the dorsal scutum. Two species were described from the Colombian Andes, P. h-inscriptum Mello-Leitão, 1941 andP. nigrolimbata Mello-Leitão, 1941. A third species, P. transversalis, was described by Roewer (1963) but has been subsequently transferred to the genus Chusgonobius Roewer, 1952 by Medrano andKury (2016). Recently, Medrano and Kury (2016) used several characters to redescribe Platymessa including those based upon the shape of the dorsal scutum, the presence of a pair of paramedian granules on scutal area V, armature of coxa IV, and the morphology of the legs. Medrano and Kury (2016) also redescribed P. h-inscriptum as the type species of the genus and considered P. nigrolimbata as a junior synonym of P. h-inscriptum. In addition, Medrano and Kury (2016) transferred Brachylibitia ectroxantha Mello-Leitão, 1941 to the genus Platymessa proposing the new combination of Platymessa ectroxantha. In this paper, we propose the recognition of a third Colombian species in the genus Platymessa Mello-Leitão, 1941 on the basis of several characters including those based upon penis morphology. This is the first record of the genus for northern Colombia.

Methods
We examined 15 males and 28 females collected from the type locality (see below). Specimens were photographed with a Leica MC-120 HD digital camera attached to a Leica S8AP0 stereomicroscope and then processed with the software CombineZP. The illustrations were made with the aid of stereomicroscope with a camera lucida, Wild type 308700, Heerbrugg Switzerland. The illustrations of the penis were made from photographs taken with an optical Leica CME microscope and the software Inkscape version 0.91. The map was made with ArcGIS.
The shape of the dorsal scutum was described using the system proposed by . We used the nomenclature for the macrosetae of the ventral plate of the penis that was proposed by Kury and Villarreal (2015), but refer to MS C3 as D1 and D1 as D2 (following system discussed in Medrano and Kury 2016). Terminology used for the description of the fields of microsetae on the ventral plate of the penis is based upon Kury (2016). Color names and codes follow Ridgway (1912 Diagnosis. This species differs from P. h-inscriptum and P. ectroxantha by the presence of multiple blunt tubercles in scutal area I, paired triangular tubercles in scutal area III, the absence of a pair of larger paramedian granules on dorsal scutal area V, lacking a ladder mask color pattern on the dorsal scutum, and instead having a V-shaped color pattern on the cephalic groove and a transverse line in the groove between areas III-IV on the dorsal scutum. Etymology. The new species is named to honor the memory of María Victoria Pinzón M. Description of the male holotype. Measurements: CL: 1,34mm; DSW: 4,17mm CW 2,31mm; DSL: 4mm; Fe: 1,4; 2,9; 2,6; 3,3 mm. Ti: 1,1; 2,6; 1,5; 1,9 mm. Dorsum (Figs 1A, C-D and 2): Dorsal scutum β shaped, body slightly convex posteriorly, cheliceral sockets shallow flanked by subsquare lateral projections and separated by a short triangular median projection. Lateral borders with granules on the protrusion of the dorsal scutum, posterior border with a row of small and scarce granules. Free tergites each with one row of round tubercles. Ocularium with a slight median depression, covered with granules arranged proportionally towards each of the eyes.  Dorsal scutum in area I with a pair of relatively large blunt tubercles and many smaller granules; area III with a pair of strongtriangular tubercles that are tilted backwards. Anal operculum with tubercles of medium size. V-shaped color pattern on the cephalic groove and a transverse, discontinuous, substraight line behind the triangular tubercles on area III in the groove between areas III-IV. Pedipalps (Fig. 3A-C). Trochanter with a subdistal seta; femur at the dorsal border with a keel and the ventral border with a row of 8 tubercles of variable size; tibia with an ectal laminar projection wider to distal part and in inner side, the projection is smaller and the same size lengthwise; tarsus with scarce setae on the dorsal surface. Chelicerae. Basichelicerite with a row of tubercles on the posterior border, the dorsal surface has small granules. Fixed finger with a row of six teeth which decrease in size towards the distal part, moveable finger with a row of 12 small denticles that are equal in size. Legs. Coxa IV with a distal prodorsal projection, ventrally with a subdistal blunt tubercle smaller than the prodorsal, clavus inguinis present. Femora of legs I and II substraight with some granules, III and IV slightly curved, in general, densely granulated, with five longitudinal rows of tubercles, the ventral tubercles are larger (Fig. 4A-E); patellae I-IV granulated; tibiae of legs III and IV slightly granulated; tarsi I with basitarsus inflated; tarsal formula: 5 (3); 9-9 (3); 7-7 (3); 7-7 (3). Genitalia (Fig. 5A-C). Ventral plate subrectangular, the basal region  is narrower than the distal, the lateral margins are subparallel and the distal margin is concave. Truncus apically thickened. On the lateral edges of the distal part of the ventral plate are two pairs of MS -C1 and C2, are strongly curved and flattened; there are two pairs of MS D1 and D2, D1 is well-developed, straight and cylindrical and shorter than C1 and C2 and MS D2 is reduced and cylindrical and occurs dorsally between MS A and C. In the basal part of the ventral plate there are two pairs of MS, A1 and A2 are both well-developed, cylindrical and anchored laterally to the ventral plate, although MS A1 is slightly more dorsal and remains aligned with the MS C1, C2 and D1 and with A2. On the ventral surface are located two pairs of MS, E1 and E2 located at the height of MS D1, both are reduced and aligned with a single pair of MS B1 located ventrally near the apical part of the truncus. On the ventral plate, the microsetae occur in the corners and extend on the lateral margins towards the proximal part of the ventral plate without touching each other. The midfield lacks microsetae. The distribution of microsetae is similar to that observed for P. h-inscriptum (Medrano and Kury, 2016).
Sexual dimorphism. Basitarsus I inflated in males (Fig. 3D), the tubercles of the femora and tibiae of legs III and IV are larger in males than in females, in general the tubercles on legs I-IV are larger in males. The dorsal scutum is almost α shape in males and γ shape in females; clavus inguinis and the body size of females is larger than that of males.  Variation. The color pattern of dorsal scutum varies especially with respect to the completeness of medial line of the dorsal scutum (Fig. 6).
Distribution. Only known from the type locality (Fig. 5). Ecology. In the Páramo de Sabana Rubia, the temperature may drop to 0 °C, the specimens were collected in the necromass of frailejones (Asteraceae).

Discussion
The genus Platymessa was revised by Medrano and Kury (2016) and the following combination of characters was used to diagnose the genus: 1) outline of the dorsal scutum β form in males and "almost" α form in females; 2) scutal area V with a pair of small paramedian granules; 3) dorsal color pattern of a "ladder mask"; 4) monomorphic chelicerae, weak with marginal rows of acuminate tubercles of variable size on posterior border; 5) groin warts present, larger in the female; 6) femora III and IV with five longitudinal rows of small tubercles; 7) basitarsomeres of leg I larger than distitarsomeres in males; and 8) cheliceral sockets shallow with lateral triangular projections. Platymessa victoriae sp. n. exhibits most of these characteristics except with respect to the armature of the dorsal scutum (scutal area III has a pair of triangular tubercles and scutal area V lacks paired paramedian granules) and the absence of a "ladder mask" with respect to the dorsal coloration. With regards to penis morphology, the shape of the ventral plate, the number and sizes of the marginal setae (MS), and the distribution of microsetae are similar between P. h-inscriptum and P. victoriae sp. n. However, there is interspecific variation with respect to the size and position of the MS on the ventral plate. In P. victoriae sp. n., MS D1 is more cylindrical and considerably shorter than C1 and C2. In addition, MS A1 and A2 are located more basally on the ventral plate and MS E1 and E2 occur between D1 and D2 (in P. h-inscriptum, MS A1 and A2 are more medial and are closer to the margin of the ventral plate and MS E1 and E2 are situated between D1 and A1).