Kankuamo marquezi Perafan , Galvis & Gutierrez

Perafan, Carlos, Galvis, William, Gutierrez, Miguel & Perez-Miles, Fernando, 2016, Kankuamo, a new theraphosid genus from Colombia (Araneae, Mygalomorphae), with a new type of urticating setae and divergent male genitalia, ZooKeys 601, pp. 89-109 : 96-103

Taxon classification Animalia Araneae Theraphosidae

Kankuamo marquezi Perafan, Galvis & Gutierrez sp. n. Figs 3, 4, 5, 6and Table 2

Type material.

Holotype male from Colombia, Magdalena, Santa Marta, Corregimiento Minca, Sector San Lorenzo, 2200m above sea level, 11.11 N, - 74.058 W, 30 -Aug-2014, leg. W. Galvis and J. Moreno (ICN-Ar 7983). Allotype female, same data as the holotype (ICN-Ar 7983). Paratypes: one female, same data as the holotype (ICN-Ar 7984); one male from the same locality as the holotype, 11.1 N, 74.05 W, 9-10-Sept-2014, leg. Miguel Gutierrez (ICN-Ar 7985).

Etymology.

The specific epithet is a noun in genitive in honor to Gabriel García Márquez (Aracataca, Colombia, 1927 - Mexico D.F., Mexico, 2014), who was a renowned Colombian writer, considered one of the most significant authors of the 20th century, and awarded the 1982 Nobel Prize in Literature for "One hundred years of solitude".

Diagnosis.

See diagnosis of the genus.

Description.

Male (holotype ICN-Ar 7982) (Figs 3 and 4). Total length, not including chelicerae or spinnerets 27; including chelicerae 30. Carapace length 12, width 11. Abdomen length 14. PLS with three segments, distal digitiform, basal length 2, medial 1.3, apical 1.6. PMS well developed mono-segmentated, length 1.3. Anterior eye row slightly procurved, posterior slightly recurved. Eyes sizes and interdistances: AME 0.43, ALE 0.56, PME 0.4, PLE 0.43, AME-AME 0.36, AME-ALE 0.13, ALE-ALE 1.26, PME-PME 0.93, PME-PLE 0.06, PLE-PLE 1.46, AME-PME 0.16, ALE-PLE 0.1. OQ elevated sub-rectangular, length 2.1, width 1.33, clypeus 0.33. Fovea transverse deep, straight, width 2.16. Cephalic area slightly raised, thoracic striations slightly conspicuous (Fig. 3A). Basal segments of chelicerae with 9 well-developed teeth on furrow promargin and 19/21 (left/right) small teeth on the proximal area of furrow, intercheliceral tumescense absent. Labium trapezoidal (Fig. 3B), length 1.46, width 2.16, with 56 cuspules. Maxillae sub-rectangular (Fig. 3B), with 56/78 (left/right) cuspules restricted on the proximal prolateral angle. Labio-sternal junction narrow in the middle with two lateral nodules. Sternum length 4.7, width 4.6, with 3 pairs of sigilla; oval, smaller pair anterior, larger pair posterior, anterior pair half distanced at half their diameter from margin, posterior pairs distanced less than 1/3 of their diameter. Superior tarsal claws with teeth on proximal half: I 4 teeth; II-IV 5 teeth. Tarsal scopulae: I-IV scopulated with distal rhomboidal group of conical setae (as Figs 5E and 5F); I and II entire; III and IV divided by a medial stripe of longer conical setae, wider in IV. Metatarsal scopulae extent: I and II scopulate on distal half; III distal 1/4; IV apically, little scopulate. Stridulatory setae absent. Type VII urticating setae present (see description), located on dorsal patch of the abdomen. Metatarsus I straight. Tibia I without apophysis (Fig. 3D). Palpal tibia with spines on ventral and prolateral faces (Fig. 3C). Cymbium bilobed. Palpal bulb sub-conical (Fig. 3 E– 3I), curved, with a wide membranous area between the subtegulum and tegulum. Distal sclerites of palpal bulb with many conspicuous keels distributed throughout most tegulum and embolus. Eleven large semicircular keels on the dorsal faces (DKs), most of them with serrated edge (Fig. 3E). Presence of PSK, AcK, PIK, AK, SAK, and approximately 14 smaller keels present on the prolateral face of proximal subtegulum (SpAcK) (Fig. 3 G– 3I). Colour (in alcochol): Cephalothorax and legs light brown with black setae. OQ with black stains and surrounded by black setae, cephalothorax with black stripes. Abdomen brown with golden setae. Iridescent scopulae and claw tuft.

Spination (proximal to distal): Femur: palp: 0V, 0D, 0-0-1P, 0R; I: 0V, 1-1-0D, 0-1-1P, 0-1-2R; II: 0V, 1-1-0D, 1-1-3P, 1-5-2R; III 0V, 1-1-0D, 0-2-1P, 0-2-3R; IV: 0V, 3-2-0D, 1-2-1P, 0-1-2R. Patella: palp: 0V, 0D, 0-2-0P, 0R; I: 0-2-2V, 0D, 0-2-0P, 0R; II: 0-0-2V, 0D, 0-2-0P, 0R; III: 0V, 0D, 0-3-0P, 0-1-0R; IV: 0V, 0D, 0-3-0P, 0-1-0R.Tibia: palp: 2-1-2V, 0D, 2-2-2P, 0R; I: 4-6-2apV, 0D, 0-2-2P, 0-1-1R; II: 3-5-2apV, 0D, 0-1-1P, 0-2-0R; III: 3-3-2apV, 0D, 2-2-1P, 2-2-1R; IV: 3-3-2-1-2apV, 0D, 2-2-2P, 1-2-2-2apR. Metatarsus: I: 2-3-1V, 0D, 0-1-1apP, 0-1-1apR; II: 3-3-1V, 0D, 0-1-1-1apP, 0-1-1apR; III: 4-4-2-1apV, 0-0-2D, 2-2-1-1apP, 1-2-1-1apR; IV: 5-5-3-1apV, 0-0-2D, 2-3-1-1apP, 2-2-1-1apR. Tarsus: palp and legs: 0. Legs and palpal segments lengths in Table 1.

Female (allotype ICN-Ar 7983) (Figs 5 and 6). Total length, not including chelicerae or spinnerets 39; including chelicerae 44.5. Carapace length 17.1, width 16.3. Abdomen length 17.4. PLS with three segments, distal digitiform, basal length 2.25, medial 1.25, apical 2.45. PMS well developed mono-segmentated, length 1.9. Anterior eye row slightly procurved, posterior recurved. Eyes sizes and interdistances: AME 0.5, ALE 0.5, PME 0.53, PLE 0.66, AME-AME 0.5, AME-ALE 0.33, ALE-ALE 2, PME-PME 1.3, PME-PLE 0.06, PLE-PLE 1.83, AME-PME 0.16, ALE-PLE 0.33. OQ elevated sub-rectangular, length 1.93, width 2.83, clypeus 0.65. Fovea transverse deep, straight, width 3. Cephalic area slightly raised, thoracic striations conspicuous with black setae (Fig. 5A). Basal segments of chelicerae with 10 well-developed teeth on furrow promargin and 21/17 (left/right) small teeth on the proximal area of furrow, intercheliceral tumescense absent. Labium trapezoidal (Fig. 5B), length 2.27, width 3.06, with 99 cuspules. Maxillae sub-rectangular (Fig. 5B), with 159/164 (left/right) cuspules restricted on the proximal prolateral angle. Labio-sternal junction narrow in the middle with two lateral nodules. Sternum (Fig. 5C) length 7.4, width 7, with three pairs of oval sigilla; posterior sigilla the largest, all of them separated from the margin by approximately their diameter. Superior tarsal claws with teeth on proximal half; palp and leg I, three teeth, smaller in palp; II four teeth; III-IV five teeth. Tarsal scopulae: palp and I-IV scopulated with distal rhomboidal group of conical setae (Fig. 5 E– 5F); palp and legs I-II entire; III and IV divided by a medial stripe of longer conical setae, wider in IV. Metatarsal scopulae extent: I scopulate on distal 2/3; II distal half; III distal 1/3; IV scopula absent. Stridulatory setae absent. Type VII urticating setae present (see description), located on dorsal patch of the abdomen. Spermathecae with two short wide rounded and granulated seminal receptacles, fused widely on a sub-rectangular wide basal plate, with several irregular sclerotized striations perpendicular to the basal edge (Fig. 5D). Color (in alcohol): darker than male. Iridescent scopulae and claw tuft.

Spination (proximal to distal): Femur: palp: 0V, 0-1-0D, 0-0-3P, 0-0-1R; I: 0V, 0-1-0D, 0-0-3P, 0R; II: 0V, 0-2-0D, 0-0-3P, 0-1-0R; III: 0V, 0D, 0-2-1P, 1-3-1R; IV: 0V, 1-0-0D, 0-0-3P, 0-0-1R. Patella: palp: 0V, 0D, 0-2-0P, 0R; I: 0V, 0D, 0-1-0P, 0R; II: 0V, 0D, 0-2-0P, 0R; III: 0V, 0D, 0-2-0P, 0R; IV: 0V, 0D, 0-1-0P, 0R. Tibia: palp: 1-4-4V, 0D, 0-3-0P, 0-1-0R; I: 0-1-2V, 0D, 1-1-0P, 0R; II: 0-2-2V, 0D, 0-2-0P, 0R; III: 3-3-3V, 0D, 2-1-2P, 1-2-1R; IV: 2-2-2V, 0D, 2-2-1P, 2-2-1R. Metatarsus: I: 1-5-1V, 0D, 0-1-1P, 0R; II: 1-5-1V, 0D, 0-0-1P, 0R; III: 4-3-5V, 0-0-2D, 2-2-2P, 1-3-1R; IV: 5-4-5V, 0-0-2D, 3-3-2P, 1-2-2R. Legs and palpal segments lengths in Table 1.

Distribution.

See distribution of the genus (Fig. 7).

Natural history.

Kankuamo marquezi sp. n. inhabits Cuchilla San Lorenzo from Sierra Nevada de Santa Marta National Natural Park. Cuchilla San Lorenzo is located in its northwestern flank, in a gradient of altitude from 2000-2300 meters above sea level, in life zone of lower montane wet forest ( Espinal and Montenegro 1963). The Sierra Nevada de Santa Marta is an isolated mountain range separated from the Andes chain. The locations where the specimens were collected are covered mainly by shrubby plants of the families Arecaceae and Chrysobalanaceae ( Cuadrado-Peña 2005), and inhabited by the snakes genus Atractus and frogs of the genera Atelopus , and the endemic species from Sierra Nevada de Santa Marta Ikakogi tayrona and Geobatrachus walkeri (MG personal observations).

Description of urticating setae type VII.

(Fig. 2)

Morphology. Urticating setae differ from body covering setae by the insertion feature through a stalk (types I, II, III and IV) or attached into a specialized socket (types V and VI) that facilitates detachment, plus presence of a penetrating acute tip, and barbs or scales that aid embedding them into targets ( Cooke et al. 1972, Bertani and Guadanucci 2013).

Urticating setae type VII are located in a dorsal wide area of the abdomen intermixed with the covering setae, and attached to the cuticle by a thinner stalk, to facilitate their release (Fig. 2G). Setae length is 1122 ± 40 µm, and width is 33 ± 3 µm, length/width ratio 34 (n=10), with a very sharp penetrating tip on the distal apex, opposite to the stalk (Fig. 2A). The stalk of the setae is larger than in the other urticating types (Fig. 2E), approximately length 45 ± 3 µm, and width 10 ± 1 µm. The main shaft is straight, having small barbs (main barbs) that extend along the whole setae (Fig. 2C, D), plus a small oval patch of lanceolated reversed barbs near the penetrating tip (Fig. 2A, B).

Main barbs are subtriangular denticles not homogeneous in size and density, longer on the basal region (Fig. 2E) and densest on the distal (Fig. 2A), and oriented with the acute extreme toward the basis of the setae. Main barbs length on distal area less than 1 µm (Fig. 2A, C), medial area around 3 µm (Fig. 2D), and on basal area of 9 ± 2 µm (Fig. 2E).

The patch of lanceolate barbs its located sub-apically at a distance approximately of 160µm from the tip to the patch centre (Fig. 2A, 2B). Patch approximately 30 µm length and width 15 µm, with around 50 lanceolate barbs. These are arranged in reversed direction, regarding the main barbs (sensu Cooke et al. 1972), oriented with the acute extreme toward the penetration tip. They are longer, broader and less acute than the main barbs (Fig. 2B); with each lanceolate barb of length 5 ± 1 µm and width 2.5 ± 0.5 µm.

Discussion. The newly characterized type VII urticating setae resemble the type II found in Aviculariinae ( Cooke et al. 1972, Bertani and Marques 1996, Bertani and Guadanucci 2013), but the main differences from those are: 1) The presence of a sub-apical oval patch of lanceolated reversed barbs, 2) The penetration tip is apical (proximal in type II), 3) The main barbs are oriented towards the base of the setae (oriented towards the apex on type II), 4) The proximal end of the setae is covered by larger main barbs, and 5) Usually, the stalk remains attached to the seta (the stalk remains attached to the body in type II).

The similarities of the morphology and size of setae type VII with type II Aviculariinae (see Cooke et al. 1972, figs 11-12, 20-21) suggest a releasing mechanism by direct contact, as indicated for Avicularia (excepting Avicularia versicolor , see Bertani et al. 2003), Iridopelma , Pachistopelma and Typhochlaena ( Bertani 2012). These tarantulas direct the abdomen toward the stimulus and transfer the urticating setae when the abdomen of the spider touches against the target ( Bertani and Marques 1996). Contrary, in Theraphosinae, the various types of urticating setae are dislodged by friction of the hind legs against the dorsum of the abdomen, and air-transported ( Cooke et al. 1972).

Bertani and Marques (1996) proposed that the differences of the shape, size and thickness between Theraphosinae and Aviculariinae urticating setae could explain the two releasing mechanisms. The morphological characteristics of all then known urticating hair types in Theraphosinae, particularly their light weight and aerodynamics, would allow them to float through the air. They suggest that short and/or thin setae with a ratio of 100:1 or 200:1 are able to float through the air. Bertani et al. (2003) compared length/width ratio between urticating setae type II and III and concluded that all airborne setae (including Avicularia versicolor type II) are narrow, mean width ranging from 6 to 7 µm, and length/width ratio ranging from 98.3 to 208.3. In contrast, for urticating setae released by direct contact with the target, the width was greater, ranging from 15 to 22 µm and the length/width ratio of 37.3-46.8 (see Bertani et al. 2003, Table 1). Here, the newly described urticating setae type VII width is 33 ± 3 µm and length/width ratio 34, which therefore represents the thickest setae known until now, and with the lowest known length/width ratio, aspects that together reinforce the hypothesis that their releasing mechanism is by direct contact.

Furthermore, the larger size, broader shape and often dispersed arrangement of many of the main barbs of Theraphosinae urticating setae (types I, III, VI, VI) involved in their urticating effects, presumably often contribute their ability to float in the air. Conversely, in both urticating setae types II and VII, which presumably do not float by air, the main barbs are only residual denticles, being much smaller than those of other types with known air dispersal.

The differences in the position of the penetrating tip between type VII and II also suggest a different penetration mechanism. On first contact with the target, the urticating setae type II pivots on its stalk so the apical end moves away from the target, while the basal penetration tip (which is actually adjacent to the stalk) instead lodges into the target as the stalk releases (see Bertani and Marques 1996, fig. 3). By contrast, the apical penetrating tip of the urticating setae type VII (at the opposite end to the stalk) is able to penetrate directly into the target, at the first contact with the object.

Experimentally, the possible mechanism of action of the urticating setae type VII was observed while handling specimens in alcohol. These urticating setae easily perforated the skin of human fingers perpendicularly. The dorsum of the tarantula’s abdomen was touched intentionally, and on further examination of the affected fingers with a stereoscope microscope, many of these setae were found embedded in the skin (Fig. 8). These setae were firmly fixed into the skin but none penetrated more than a third of their length. When we attempted to remove them from the skin, these setae were easily broken at their distal end. Based on our observations together, our assumption is that the patch of the lanceolate reverse barbs in the distal area can serve as a breakpoint into the skin, ensuring that the apex of the seta remains within the tissues.

Another aspect to consider is that all previously known species with contact urticating setae have leg spines absent or reduced ( Cooke et al. 1972, Bertani et al. 2003). Kankuamo gen. n. therefore represents a remarkable exception to this suggested character association because, in contrast, they do have legs with some spines, mainly conspicuous on metatarsi and tarsi of hind-leg pair IV. Leg spines in other theraphosids have been functionally associated with releasing of airborne urticating setae by facilitating rubbing, with the exception of Avicularia versicolor which use claw tufts for rubbing ( Cooke et al. 1972, Bertani and Marques 1996, Bertani and Guadanucci 2013). One possible interpretation is the plesiomorphic retention of contact setae could reflect a close phylogenetic relationship between Aviculariinae and Theraphosinae, as proposed by Pérez-Miles et al. (1996). In this scenario, the additional development of posterior leg spines (such as found in Kankuamo gen. n.) could have facilitated the evolutionary transformation of contact setae into derived airborne setae, which are now widespread among Theraphosinae. However, if contact setae are interpreted as derived, the posterior leg spines present in Kankuamo gen n. could be regarded as a plesiomorphic retention.