Stygnus apaporis, Villarreal & Ahumada-C & Flórez, 2024

Villarreal, Osvaldo, Ahumada-C, Daniela & Flórez, Eduardo, 2024, A glimpse into the diversity of Stygnus Perty, 1833: A new Colombian species and additional records from South America (Opiliones, Stygnidae), European Journal of Taxonomy 970, pp. 203-229 : 206-212

Stygnus apaporis sp. nov.

urn:lsid:zoobank.org:act:6634E95B-5B9A-4418-9198-5243EF7BC821

Figs 1–3 , 4A–C , 13

Diagnosis

The species resembles Stygnus kuryi Pinto-da-Rocha & Tourinho, 2012 in the morphology of legs IV of the males and the genital morphology. However, the new species can be differentiated from Stygnus kuryi by its size ( S. kuryi is clearly larger: DSL 4.4 vs 2.12 mm, DSW 3.7 vs 2.23), coloration ( S. kuryi is darker than S. apaporis sp. nov.) ( Fig. 1 ) and the ornamentation of the femur IV of the males ( S. apaporis has a proventral row of tubercles, absent in S. kuryi ) ( Fig. 3B ). The penises of both species have some differences: the shape and distribution of MSC (in S. apaporis they are small and aligned, whereas in S. kuryi they are large and grouped) ( Fig. 4A–C ); the shape of the malleus (in S. kuryi the malleus is expanded dorsally) ( Fig. 4A–B ) and the shape of the complex gland and stylus (G+S): the size of the dorsal process and elongated shape of the G+S ( Fig. 4A–B ).

Etymology

The species name is a noun in apposition and refers to the type locality,Apaporis, an important Amazonian river of the departments of Vaupés and Guaviare in Colombia. It is a tributary of the Caquetá River. In the last stretches, before the river joins the Caquetá, it forms part of the boundary between Colombia and Brazil.

Type material

Holotype COLOMBIA – Vaupés • ♂; Lago Taraira, Estación Biológica Mosiro Itájura Caparú ; 1°04′ S, 69°30′ W; alt. 200 m; 2002–2004; J. Pinzón leg.; ICN-Ao 1890 .

Paratypes COLOMBIA – Guaviare • 1 ♀; San José del Guaviare, vereda Playa Güio Las Iracas ; 2°34′37.5″ N, 72°43′21.1″ W; alt. 208 m; 20 Oct. 2012; D. Luna leg.; ICN-Ao 1128 . – Vaupés • 4 ♂♂, 4 ♀♀; same data as for holotype; ICN-Ao 978 .

Description

Males

MEASUREMENTS. Male holotype (ICN-Ao 1890). DSL = 2.12; DSW = 2.23; ID = 1.51; pedipalpus: coxa = 0.27, trochanter = 0.37, femur = 1.87, patella = 0.90, tibia = 0.63, tarsus = 0.62, total = 4.66; leg IV: coxa = 0.62, trochanter = 0.49, femur = 3.47, tibia = 1.65, metatarsus = 2.98, total = 11.25.

DORSUM ( Figs 1–2 ). Dorsal scutum outline of beta type.Anterior area of DS with large, scattered granules. Cheliceral sockets shallow and narrow, between two short processes, and with a medial wide and short process. Eyes with a row of 3–4 medium granules, placed posteriorly on carapace. Interocular region with one large spine and six granules in base. Laterals margins of DS with medium scattered granules. Mesotergum divided into three areas: I divided medially in two halves, with eight–ten large granules on each side; II with about 25 granules organized approximately in a transverse medial row; III with about 22 scattered granules, grouped mainly in lateral region, and with a pair of paramedian divergent and very large backwards spines, with base granulated. Posterior margin slightly convex with a row of granules. Free tergites I–III with a row of granules, and a paramedian pair of large tubercles (3>2> 1).

VENTER ( Figs 1D , 2B ). Coxa I with small, scattered granules; II with a medial row of small granules and three apicals; III with small, scattered granules, and posterior margin with a row of medium granules; IV with distal tubercle and scattered granules. Genital operculum with five small granules. Free sternites with a row of small granules.

CHELICERAE ( Figs 1B , 2A–B ). Segment I with four–five dorsoectal and proximal granules on bulla; II inflated, with small, scattered granules in the ectal side; fixed finger with three distal teeth (iii); mobile finger with a large basal tooth and with three distal teeth (I_Iii).

PEDIPALPS ( Fig. 2C–D ). Coxa dorsally with one basal and one distal small tubercle; ventrally with two conspicuous tubercles; and two conspicuous ectal tubercles. Trochanter dorsally and ventrally with one large medial tubercle, with one additional medium basal tubercle on the ventral side. Femur dorsally and ventrally with a row of small granules, and one mesal medium tubercle on distal portion. Patella slightly swollen distally, with one tubercle and scattered small granules in ectal side. Tibia dorsally smooth, ventrally with scattered, small granules; tibia mesal IIIIi, ectal IIiIi. Tarsus dorsally smooth, ventrally with scattered, small granules; tarsus mesal IIi, ectal Iiii.

LEGS ( Fig. 3A–D ). The leg segments (femur, patella, tibia) have longitudinal rows of tubercles (more or less arranged in seven rows on the femur). Coxae I–III dorsally and ventrally with some granules; IV with one longitudinal row of tubercles of different sizes, and one medial apophysis in distal portion. Trochanter I with three prodorsal tubercles; II smooth; III with one retrodorsal row of small tubercles; IV with one retrodorsal tubercle and scattered granules. Femora I–II with one retrodorsal and prodorsal row of small tubercles; III with one prolateral row of tubercles increasing in size distally and a retrolateral row of small tubercles; IV with one dorsal and one prodorsal row of tubercles of similar size (distal-most tubercle of prodorsal row conical), one prolateral and one retrolateral row of tubercles of different sizes, and one proventral and one retroventral row of tubercles increasing in size distally (distal-most tubercle of proventral row conical and thicker than others). Patellae I–II dorsally and ventrally with some minute granules; III with one retrodorsal row of medium tubercles; IV with one retrodorsal row of tubercles increasing in size distally (distal-most tubercle of row conical and thicker than others), and one prolateral row of four tubercles, third tubercle larger than others. Tibiae I–III dorsally and ventrally with some minute granules; tibiae VI with one dorsal and prodorsal row of small granules, and one prolateral and retrodorsal row of medium tubercles; IV ventrally with two apical conical tubercles. Metatarsi I–IV smooth. Basitarsus I inflated and two times as long as other tarsomerus. Tarsi I–II each with one smooth claw; III–IV with two smooth subparallel claws and tarsal process reduced. Legs III–IV without tarsal scopula. Tarsal segmentation: 7(3)/11(3)/5/6.

PENIS ( Fig. 4A–C ). LP trapezoidal in dorsoventral view, with distal border rounded; LP clearly differentiated from truncus/malleus by a ventral crack. Stylus dorsally curved, with a short triangular dorsal process. All MS A-D located on LP and not on truncus: MS-A1–3 straight, forming a transverse straight line, inserted at base of LP, slightly distal to insertion of gland; MS-B absent; MS-C1–3 inserted in dorsomedial region of LP, large and slightly curved, positioned dorsolaterally, forming an inclined row on longitudinal axis and equally spaced from each other; MS-D1 positioned medially on dorsal face of LP, MS-D2 absent; only one pair of MS-E, minute and conical, observed, probably due to optical limitations.

COLORATION ( Fig. 1A–D ). Body and appendages Strong Orange (55); prosoma reticulated, Deep yellowish brown (75) on Strong yellowish brown (74); dorsal scutum margin Deep yellowish brown (75); coxae I– III and pedipalps (except coxa) Brilliant yellow (83); chelicerae reticulated, Deep yellowish brown (75) on Strong yellowish brown (74); ocularium bases Dark olive (108); tips of area III paramedian spines and free tergite III Vivid yellow (82).

Females

Similar to males, except for: chelicera not swollen; legs finely granular; distitarsus I not inflated and elongated; legs IV without large tubercles. Pedipalpal tibia mesal IIIIi, ectal IIiIi; tarsus mesal Iii, ectal IiIi (constant in most females).

Intraspecific variations

Paratype measurements (females n = 5, min–max): dorsal scutum length = 2.15–2.30; dorsal scutum width = 1.94–2.25; interocular distance = 1.3–1.4; pedipalp: coxa = 0.15–0.31, trochanter = 0.24–0.49, femur = 1.12–1.78, patella = 0.54–1.13, tibia = 0.50–0.70, tarsus = 0.45–0.60, total = 3.70–4.50; leg IV: femur = 2.8–3.20, tibia = 1.16–1.70, metatarsus = 3.0–3.12, total = 10.46–10.52; (males n = 2, min–max): dorsal scutum length = 2.85–2.88; dorsal scutum width = 2.22–2.31; interocular distance = 1.00–1.05; pedipalp: coxa = 0.50–0.81, trochanter =?–0.44, femur =?–1.40, patella =?–1.45, tibia =?–1.00, tarsus =?–0.76, total =?–5.86; leg IV: femur = 3.35–3.58, tibia =?–1.78, metatarsus =?–3.64, total =?–10.88.

Spines of the tibia and tarsus of the pedipalps of different sizes in some males and females.

Habitat remarks

Stygnus apaporis sp. nov. inhabits localities characterized by tropical humid forests in the departments of Vaupés and Guaviare. These areas, including the Parque Nacional Natural (PNN) Serranía del Chiribiquete, the PNN Nukak and the PNN Amacayacu, are experiencing escalating deforestation, due to the expansion of agricultural and livestock activities in the post-conflict period in Colombia ( Clerici et al. 2020).

Distribution ( Fig. 13 )

Colombia, Vaupés: Lago Taraira, Estación Biológica Mosiro Itájura Caparú, and Guaviare: San José del Guaviare, vereda Playa Güio Las Iracas.

Figures

Fig. 1. Stygnus apaporis sp. nov., holotype (ICN-AO-1890). A. Habitus, panoramic dorsal view. B. Detail of dorsal scutum and chelicerae, dorsal view. C. Panoramic lateral view. D. Detail of the body and chelicera, lateral view. Scale bars = 1 mm.

Fig. 2. Stygnus apaporis sp. nov., holotype (ICN-Ao-1890). A–B. Habitus, dorsal (A) and lateral (B) views. C–D. Right pedipalp, mesal (C) and ectal (D) views. Membrane zones are represented in light yellow. Scale bars = 1 mm.

Fig. 3. Stygnus apaporis sp. nov., holotype (ICN-Ao-1890). A–D. Right leg IV: dorsal (A), ventral (B), prolateral (C) and retrolateral (D) views. The color of each longitudinal row of tubercles is defined in the inset. The membrane zones are represented in light yellow. Scale bars = 1 mm.

Fig. 4. Stygnus spp., apical portion of the penis. A, D, F. Dorsal view. B, E, G. Lateral view. C. Ventral view. A–C. S. apaporis sp. nov., paratype (ICN-Ao 978). D–E. Stygnus nogueirai Pinto-da-Rocha & Tourinho, 2012 (ICN-Ao 485). F–G. Stygnus simplex (Roewer, 1913) (ICN-Ao 1889). Arrow in B indicates the ventral crack. Abbreviation: MS = macrosetae. Macrosetae group A (MS A) is represented in blue, group C (MS C) is represented in pink, group D (MS D) is represented in yellow and group E (MS E) is represented in green. Scale bars = 1 mm. Figures D–E not to scale.

Fig. 13. Maps showing the geographical distribution of the genus Stygnus Perty, 1833. A. Previous records in the literature and photographic records. B. New records for Colombia.