Arboriticus giganteus Borges and Bertani, 2025

Borges, Leandro Malta, Abegg, Arthur Diesel, Paladini, Andressa & Bertani, Rogério, 2025, A new genus and five new species of arboreal tarantulas (Araneae: Theraphosidae) from Brazil, Zootaxa 5679 (4), pp. 521-551 : 538-541

publication ID	https://doi.org/10.11646/zootaxa.5679.4.4
publication LSID	lsid:zoobank.org:pub:FBAE6047-FC82-4A66-9FF7-80F9DC768E4E
persistent identifier	https://treatment.plazi.org/id/03EC1C29-FFF7-FF9E-FF7A-FB576CE0F876
treatment provided by	Plazi
scientific name	Arboriticus giganteus Borges and Bertani
status	gen. nov.

Treatment

Arboriticus giganteus Borges and Bertani gen. nov. sp. nov.

( Figs 1 View FIGURE 1 , 46 View FIGURES 46 –60, 85)

Gen. sp. 3; Bertani, 2023:14–15, 19, 23.

Diagnosis. Males can be distinguished from those of all other species of the genus by the developed bulb keels, the presence of a SA keel (Figs 48–50), and incrassate tibia IV ( Fig. 59 View FIGURES 59 ). Females resemble those of A. spinosissimus gen. nov. comb. nov., A. tarsicrassus gen. nov. comb. nov. and A. celsoi gen. nov. sp. nov. by the incrassated metatarsus IV with stiff setae (Fig. 60). They can be distinguished from those of A. spinosissimus gen. nov. comb. nov. and A. celsoi gen. nov. sp. nov. by the spermathecae stalk width narrower than the sub-spherical bulb (Fig. 56). From A. tarsicrassus gen. nov. comb. nov., they can be distinguished by the large size and strongly incrassate tibia and metatarsus IV (Fig. 60).

Etymology. The specific epithet “giganteus ” is a Greek word for “giant”, referring to the large size of the specimens of this species.

Type material. Holotype male, from Brazil, state of Espírito Santo, Near Aracruz and Coqueiral [19º54’S, 40º13’W] 38 m a.s.l., Y. Wehr col., II.1981 ( IBSP 4667 View Materials ) GoogleMaps ; Paratype female from Brazil, state of Espírito Santo, Estação Biológica Santa Lúcia [19º57’S, 40º32’W] 663 m a.s.l., D. Pedroso col., 18 January 2004 ( MNRJ 07540 View Materials ) GoogleMaps .

Description. Holotype male ( Figs 46 View FIGURES 46 –53, 59) IBSP 4667. Carapace 18.90 long, 17.06 wide, chelicerae 8.80. Legs (femur, patella, tibia, metatarsus, tarsus, total): I: 20.41, 9.45, 16.99, 18.25, 11.01, 76.11. II: 19.11, 8.89, 15.64, 17.03, 10.94, 71.61. III: 17.01, 8.17, 13.92, 16.99, 9.53, 65.62. IV: 21.37, 8.90, 19.15, 25.86, 11.58, 86.86. Palp: 11.38, 6.29, –, 3.73, 31.66. Midwidths: femora I–V = 3.13, 3.20, 4.11, 3.54, palp = 2.29; patellae I–IV = 3.37, 3.26,

3.48, 3.82, palp = 2.53; tibiae I–IV = 2.62, 2.48, 2.70, 3.12, palp = 2.49; metatarsi I–IV = 1.68, 1.72, 1.71, 2.28; tarsi I–IV = 1.54, 1.53, 1.57, 1.64, palp = 2.00.Abdomen 18.82 long, 11.96 wide. Spinnerets: PMS, 1.54 long, 0.87 wide, 0.28 apart; PLS, 2.29 basal, 2.90 middle, 2.90 distal; midwidths 1.29, 1.22, 0.87, respectively.

Carapace ( Fig. 46 View FIGURES 46 ): 1.10 longer than wide; cephalic area moderately raised. Fovea: Straight, 2.49 wide. Eyes and eye tubercle: Tubercle 0.99 high, 1.95 long, 3.48 wide. Clypeus 0.20 wide. Sizes and inter-distances:AME 0.49, ALE, 0.53, PME 0.34, PLE 0.55, AME–AME 0.33, AME–ALE 0.26, AME–PME 0.18, ALE–ALE 1.98,ALE–PME 0.44, PME–PME 1.48, PME–PLE 0.13, PLE–PLE 2.02, ALE–PLE 0.37, AME–PLE 0.56. Eye group 3.24 wide, 1.46 long. Maxillae: Length 5.59, width 2.91. Cuspules ca. 138 spread over ventral inner heel. Labium: 2.01 long, 2.88 wide, with ca. 110 cuspules spaced by ca. one diameter from each other on anterior third center (Fig. 47). Chelicerae: Basal segment with 11 teeth in row on promargin and denticles in basal area. Sternum: 8.48 long, 6.79 wide. Sigilla: first pair rounded, second and third ovals (Fig. 47).

Legs: formula IV I II III. Length leg IV to I: 1.14. Scopula: Tarsi I – IV fully scopulate. Metatarsi I – II fully scopulate; III 1 /2, IV 1 /6 distal scopulate. Metatarsus IV divided by row of 2–3 setae. Spination: palp: femur 0, patella 0, tibia v0-2-1; leg I: femur p0-0-1, patella 0, tibia p0-0-1, r0-0-1, metatarsus v0-0-1ap; leg II: femur 0, patella 0, tibia v0-1-3ap, p0-1-0, metatarsus v0-0-3ap; leg III: femur 0, patella 0, tibia v0-1-3ap, p1-1-1, r0-1-1, metatarsus v2-1-2ap, p1-0-1, r0-1-1; leg IV: femur 0, patella 0, tibia v0-1-5(3ap), r0-0-1, metatarsus v17(3ap), p1- 0-1. Spiniform setae a few, on superior retrolateral maxillae; several on retrolateral coxa II on superior and inferior areas, and a shield of spiniform setae on retrolateral coxa III; spiniform setae on basal prolateral coxae II, III and IV. Tibia IV slightly incrassated on distal half. STC: a single row of 5–7 small teeth on legs I– IV. Urticating setae: Only type I, position and length range: MA, 0.30–0.34. Other areas of abdomen dorsum bald. Distribution of urticating setae on the abdomen dorsum unknown due to large bald area .

Palp (Figs 48–50). Bulb pyriform, embolus slightly longer than tegulum length, slightly flattened at distal region, apex short and thick. Prolateral keels present. PS forming embolus edge distally. PI present. A keel short. R sharp. SA well developed.

Bifid tibial spur (Figs 51–53) with two straight processes originating from common base, RP longest, slightly curved at distal portion. A single, flattened, rhomboidal spine contiguous to the internal upper face of the RP and another on the internal face of the PP. Metatarsus I curved at its basal third, when folded touches the retrolateral side of the RP (Fig. 51).

Color pattern (in alcohol): Carapace and chelicerae light brown. Legs light brown with some light brown long setae. Coxae of legs ventrally and sternum light brown, covered with short light brown setae. Labium and maxillae light brown. Abdomen dorsally black with long yellowish brown setae, ventrally yellowish brown. Femora, patellae, tibiae and metatarsi of legs and palp with light stripes. Apex of leg and palp segments with whitish rings on apex.

Description. Paratype female ( Figs 54 View FIGURES 54 –58, 60) MNRJ 07540. Carapace 18.42 long, 15.81 wide, chelicerae 10.50. Legs (femur, patella, tibia, metatarsus, tarsus, total): I: 13.39, 8.19, 10.80, 9.66, 7.66, 49.70. II: 12.34, 6.91, 9.07, 8.81, 7.58, 44.71. III: 11.29, 6.40, 9.23, 9.75, 6.95, 43.62. IV: 15.56, 7.70, 13.54, 15.66, 7.72, 60.18. Palp: 9.75, 5.73, 7.04, –, 7.50, 30.02. Midwidths: femora I–V = 2.47, 2.68, 3.30, 3.27, palp = 2.09; patellae I–IV = 3.14, 3.02, 3.38, 3.81, palp = 2.56; tibiae I–IV = 2.80, 2.70, 3.00, 4.82, palp = 2.41; metatarsi I–IV = 2.44, 2.23, 2.25, 4.16; tarsi I–IV = 2.17, 2.14, 2.15, 2.21, palp = 2.30. Abdomen 25.43 long, 15.13 wide. Spinnerets: PMS, 2.41 long, 1.08 wide, 1.59 apart; PLS, 3.79 basal, 2.74 middle, 3.43 distal; midwidths 1.88, 1.64, 1.23, respectively.

Carapace ( Fig. 54 View FIGURES 54 ): 1.16 longer than wide; cephalic area moderately raised. Fovea: Straight, 3.41 wide. Eyes and eye tubercle: Tubercle 1.18 high, 2.65 long, 3.55 wide. Clypeus 0.27 wide. Eye sizes and inter-distances: AME 0.70, ALE, 0.83, PME 0.38, PLE 0.62, AME–AME 0.24, AME–ALE 0.31, AME–PME 0.21, ALE–ALE 2.27, ALE–PME 0.41, PME–PME 1.72, PME–PLE 0.04, PLE–PLE 2.40, ALE–PLE 0.30, AME–PLE 0.62. Eye group 3.53 wide, 1.63 long. Maxillae: Length 5.86, width 3.33. Cuspules ca. 302 spread over ventral inner heel. Labium: 2.54 long, 3.14 wide, with ca. 147 cuspules spaced by ca. one diameter from each other on the anterior third center (Fig. 55). Chelicerae: Basal segment with 11 teeth on promargin and denticles on basal area. Sternum: 8.48 long, 7.13 wide. Sigilla: first pair rounded, second and third ovals, all less than a diameter from margin (Fig. 55).

Legs: formula IV I II III. Length leg IV to leg I: 1.21. Scopula: Tarsi I – IV fully scopulate. Metatarsi I – II fully scopulate; III 1 /2, IV 1 /4 distal scopulate. Metatarsus IV divided by row of 2–3 setae. Spination: palp: femur p0-0-1, patella 0, tibia v0-1-4(3ap), p0-1-1, r0-0-1; leg I: femur p0-0-1, patella 0, tibia v0-0-2(1ap), metatarsus v0-0-1ap; leg II: femur p0-0-1, patella 0, tibia v0-1-2ap, p0-1-0, metatarsus v0-0-2ap; leg III: femur 0, patella 0, tibia v0-1-2ap, p1-1-1, r0-1-1, metatarsus v0-2-3ap, p0-1-1, r0-1-1; leg IV: femur 0, patella 0, tibia v1-2-4(3ap), p0-1-0, r0-1-1, metatarsus v20(4ap), p0-1-1, r0-1-1. Spiniform setae: retrolateral maxillae and coxa I with few spiniform setae on superior area; coxa III with conspicuous spiniform setae on superior and inferior areas; coxa IV forming black shield of spiniform setae on superior, middle and inferior areas. Prolateral coxa I lacking spiniform setae, on coxae II and III, on IV they are more conspicuous on superior, middle and inferior edge (Figs 57–58). STC: single row of 2–5 small teeth on legs I– IV. Tibia IV incrassate on distal half, metatarsus IV incrassate, mainly on its basal half portion, covered with spiniform long setae (Fig. 60). Urticating setae: Only type I present, position and length range: LA, 0.33–0.38, LM, 0.36–0.44, LP, 0.37–0.43, MA, 0.36–0.39, MM, 0.47–0.48, MP, 0.45–0.50). Distribution of setae on the abdomen dorsum as in Bertani & Guadanucci (2013, fig. 5) .

Spermathecae: Two short spermathecae separated by short weakly sclerotized area, spermathecal stalk narrower than rounded spermathecal bulb (Fig. 56).

Color pattern (in alcohol): Carapace and chelicerae brown. Legs brown with some light brown long setae. Coxae of legs ventrally and sternum brown, covered with short light brown setae. Labium and maxillae reddish brown. Abdomen dorsally and ventrally black with long yellowish setae. Femora, patellae, tibiae and metatarsi of legs and palp with discrete whitish stripes. Apex of leg and palp segments with whitish rings on apex.

Distribution. Known only from two localities in the Atlantic Forest, Brazilian state of Espírito Santo ( Fig. 1 View FIGURE 1 ).