Maracaynatum isadorae Colmenares & Tourinho, 2016, sp. nov.
Creators: name: Colmenares, Pío A.
name: Tourinho, Ana Lúcia
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Opiliones
Samoidae
Maracaynatum
Maracaynatum isadorae

description: Maracaynatum isadorae sp. nov.
Figs. 1–3
Type material. Holotype male (INPA-OPI 003417) from the Fazenda da Universidade Federal do Amazonas (Fazenda UFAM), Manaus, Amazonas, Brazil; 28–30.vii.2011; Leg. Larissa Lança; Winkler technique. Paratypes: 1 male (INPA-OP 1008) from Fazenda UFAM, L2-500, Manaus, Amazonas, Brazil; 28.vii.2010; Leg. Larissa Lança; Beating technique. 1 female (INPA-OP 1557) from Fazenda UFAM, L3-500, Manaus, Amazonas, Brazil; 23.viii.2010; Leg. O. Ferreira da Silva; Beating technique. 2 males and 1 female (INPA-OPI 003491) with same data as holotype (one male with dissected genitalia and appendages). 1 female (INPA-OP 1009) from Fazenda UFAM, L3–500, Manaus, Amazonas, Brazil; 23.viii.2010; Leg. Larissa Lança; Beating technique. 1 male (INPA- OP 2551) from Reserva Ducke, LO 5-2500, Manaus, Amazonas, Brazil; 06.vi.2012; Leg. O. Ferreira; cryptic manual searching. 1 male (INPA-OP 3308) from Reserva Ducke, LO 3-500, Manaus, Amazonas, Brazil; 16.xii.2013; Leg. P. Colmenares & A. Tourinho; cryptic manual searching. 1 female (INPA-OP 4432) from Reserva Ducke, LO 7-1500, Manaus, Amazonas, Brazil; 27.vii.2014; Leg. P. Colmenares; cryptic manual searching. 1 male (INPA-OP 3929) from BR-319 road, km 260, Igapó-Açu, Amazonas, Brazil; 10.xii.2012; Leg. P. Colmenares; cryptic manual searching; in ethanol 100%. 3 males and 3 females (INPA-OPI 003421) from Rio Preto da Eva, Amazonas, Brazil; 13.i.2006; Leg. R. Saturnino & A. Tourinho; Beating technique. 1 male (INPA-OPI 003420) from Rio Preto da Eva, Amazonas, Brazil; 13.i.2006; Leg. R. Saturnino & A. Tourinho; Beating technique. 2 females (IB-5799) from PDBFF, Manaus, Amazonas, Brazil; 2001–2003; Leg. F. Rego; sample 165A. 3 males (IB- 5818) from PDBFF, Manaus, Amazonas, Brazil; 2001–2003; Leg. F. Rego; sample 94 A. Other material: 3 males and 2 females (INPA-OP 4424) from Reserva Ducke, LO 7-1500, Manaus, Amazonas, Brazil; 27.vii.2014; Leg. P. Colmenares; cryptic manual searching; in ethanol 100%.
Etymology. Patronymic in honor to our collaborator Merle Isadora Williams, a graphic designer who has been of great help to our lab, not only by improving the quality of our illustrations with her advice and digital editing, but also by acting as an assistant during field work and English language review.
Diagnosis. The new species is similar to Maracaynatum cubanum Šilhavý, 1979, from which differs by having three strong setiferous tubercles instead of two on the pedipalpal patella. Different from all remaining species by the shape of the stridulatory organ on the mesal face of cheliceral segment I, which is composed by two ellipsoidal tubercles and one small proximal tubercle. Penis easily distinguishable from all remaining species by the capsula interna, which has bifid conductors and a bifid stylus.
Description. Male holotype. Measurements: DSL: 1.18; PL: 0.31; DSW: 0.88; PW: 0.55; ID: 0.10; MH: 0.74.
Dorsum (Figs. 1 A–B). Dorsal scutum guitar-shaped in dorsal view, with the narrowest width between the prosoma and opisthosoma. Prosoma: anterior margin with one tubercle on each corner, with two clear cuticle areas on the cheliceral sockets, almost reaching the ocularium. Ocularium round and elevated in lateral view, placed in the middle of the prosoma and densely covered with small tubercles. Opisthosoma: higher than prosoma in lateral view, with four areas barely recognizable, wider at area IV and densely granulated. Sulci barely recognizable. Lateral and posterior margin with a row of minute tubercles. Free tergites with rows of minute setiferous tubercles.
Venter: Coxa I with two rows of 3–5 well developed tubercles and one larger apical anterior tubercle; II with two rows of small tubercles and two larger posterior tubercles; III with sparse minute tubercles; IV with sparse minute tubercles, two anterior and two posterior larger tubercles near the stigmatic area. Genital operculum slightly triangular. Free sternites and anal plate with rows of small setiferous tubercles.
Chelicerae (Fig. 1 C). Not swollen. Segment I with well developed bulla and one stridulatory organ consisting of three elliptical ridges (Šilhavý 1979) (Fig. 1 D) on the mesal face, consisting of sclerotized projections of the cuticle, elevated and with well defined margins. Segment II with 3–4 frontal and pointed tubercles, some distal setae and five distal teeth. Segment III with 3–4 teeth.
Pedipalps (Figs. 1 E–F). Coxa with one ventral large tubercle. Trochanter with two ventral large tubercles. Femur ventrally with two basal, one medial, and one subapical strong setiferous tubercles, and one mesal subapical strong setiferous tubercle. Patella with one ectal and two mesal strong setiferous tubercles. Tibia with three ectal (IIi) and three mesal (IiI) strong setiferous tubercles. Tarsus with two ectal and two mesal strong setiferous tubercles equal in size and with several setae between them.
Legs (Figs. 1 B, 1G). All segments without armature only covered with fine and small setae. Metatarsus III not modified. Tarsal formula: 4(2)/6(3)/5/6; first segment of basitarsus and last segment of distitarsus II longer than remaining segments; first segment of basitarsus III–IV longer than remaining tarsal segment (Fig. 1 B). Scopula on tarsi III–IV (Fig. 1 G).
Penis (Figs. 2 A–G). Truncus thinner basally and swollen distally, ventrally with a transversal hump and low dorsal hump, both more recognizable in lateral view and located in the region between pars basalis and pars distalis. Pars distalis slightly compressed dorso-ventrally; Lamina apicalis short, not modified into a calyx; six pairs of ventro-lateral foliar macrosetae, in three groups: three basal, one medial, and two distal; one pair of acuminate ventro-distal macrosetae (Fig. 2 C). Capsula externa represented by an eversible membranous follis (Figs. 2 A–B). Capsula interna fully eversible, composed of free and flattened stylus, with a bifid tip (Fig. 2 B) and two laminar, rigid, and divergent conductors, basally fused and ending in bifid tips that fold on lateral margins of pars distalis when in non-expanded position (Fig. 2 B). When the penis is expanded the conductors and stylus are projected distally, and the follis is inflated, expanding dorsally (Figs. 2 D–F).
Color (Figs. 1 A–B). Body yellowish, darker at prosoma and legs, from femora to metatarsi. Tarsi clearer than the rest of the body. Dark reticled areas on prosoma. Lateral portions of scutal areas, free tergites, complete anal plate and last esternite with dark colored areas.
Female (paratype INPA-OP 1557): Measurements: DSL: 1.38; PL: 0.42; DSW: 1.36; PW: 0.74; ID: 0.19; MH: 1.21. Very similar to male. Segment I of chelicerae without stridulatory organ.
Natural history. This species seems to be a tree climber that spends the day on palms and trees, descending at night. It can be found in the lower parts of tree trunks and occasionally in the litter. The number of specimens found in a few lots obtained by beating technique suggests that multiple individuals of M. isadorae sp. nov. can be found in the same place. Another species of the genus, M. linaresi, was observed climbing walls in small groups in the mountains of the Sierra de Perijá National Park, state of Zulia, Venezuela (Colmenares, unpublished data), suggesting some degree of gregarism. Another samoid not identified yet has been seen in groups climbing trees during the night in Reserva Ducke (Colmenares, unpublished data).
Distribution. Brazil: Amazonas: Fazenda UFAM; Reserva Ducke, Manaus; Rio Preto da Eva; Igapó Açu, BR- 319 (Fig. 3).
Comparisons. Maracaynatum isadorae sp. nov. seems to be a very unique species within Maracaynatum, regarding the genital morphology. So far, is the only species of the genus with a bifid stylus. Also, the tips of the conductors in this species are bifid. These two features could be autapomorphic for this species. The only other species showing bifid conductors is M. linaresi, but in that species the bifurcation happens more in the middle of the conductors and not in the tips (see Soares & Avram 1981). Regarding the external morphology, the new species resembles the Caribbean taxa: M. cubanum, Maracaynatum trinidadense Šilhavý, 1979 and Maracaynatum stridulans Šilhavý, 1979. The males of the species in this group have very similar cheliceral morphology, having stridulatory organs in the shape of ellipsoidal flat tubercles with engrossed margins and a darker central area (Šilhavý 1979). Maracaynatum stridulans has a stridulatory organ composed of seven ridges, whereas the organ of M. trinidadense has only two, and the organ of M. cubanum has two complete ridges and a small proximal tubercle, like M. isadorae sp. nov. Another feature is the cheliceral segment II, which is armed with three acuminate tubercles in M. stridulans and M. isadorae sp. nov., a few small setiferous tubercles in M. cubanum, and is only covered with setae in M. trinidadense. They also share a few characters in the genital morphology, such as the shape of the conductors, which are all laminar and curved distally. Horeover, given the homogeneity in the external morphology of the genus and without more detail about the genital morphology of the remaining species, it is difficult to offer more accurate comparisons.
description: Published as part of Colmenares, Pío A. & Tourinho, Ana Lúcia, 2016, First Amazonian species of Maracaynatum, with comments on the genus (Opiliones: Laniatores: Samoidae), pp. 565-572 in Zootaxa 4193 (3) on pages 566-569, DOI: 10.11646/zootaxa.4193.3.6, http://zenodo.org/record/167241