Arboriticus tarsicrassus, Borges & Abegg & Paladini & 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 : 531-532

Arboriticus tarsicrassus gen. nov. comb. nov. syn. rev.

( Figs 1 , 19 –29, 85)

Eupalaestrus tarsicrassus Bücherl, 1947: 298 ; Bücherl, 1957: 300, figs 74, 74a (male, misidentification); Lucas & Bücherl, 1973: 246, fig. 8; Bertani, 2001: 283, figs 19, 56–57 (syn. of E. spinosissimus , misidentification).

Gen. sp. 2: Bertani, 2023: 14–15, 19, 23.

Diagnosis. Males resemble those of A. minor gen. nov. sp. nov. and A. petropolis gen. nov. sp. nov. by the reduced male palpal bulb keels (Figs 21–23) in conjunction with the metatarsus I touching the retrolateral process of the tibial spur laterally when flexed. They can be distinguished from those of A. minor gen. nov. sp. nov. by the PP of tibial spur not being thickened and the RP longer than the PP (Figs 24–26). From A. petropolis gen. nov. sp. nov., they can be distinguished by the tegulum not elongated and embolus narrowing abruptly from the tegulum (Figs 21–23). Females resemble those of A. spinosissimus gen. nov. comb. nov., A. giganteus gen. nov. sp. nov., and A. celsoi gen. nov. sp. nov. by the incrassate metatarsus IV with stiff setae (Fig. 29). 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. 28). From A. giganteus gen. nov. sp. nov. they can be distinguished by the small size and slightly incrassate tibia and metatarsus IV (Fig. 29).

Type material. Holotype female from Brazil, state of São Paulo, São José dos Campos [23º13’S, 45º53’W, 602 m a. s. l.], Fábrica de Louças leg., 5 August 1947, IBSP 593 .

Other material examined. Brazil, state of São Paulo, Jacareí, Estrada Turística de Igaratá , km 2 [23º18’S, 45º57’W, 582 m a.s.l.], 1 male, A. Zanotti & J. Latuffi leg., 1999, IBSP 8064 .

Description. Male (IBSP8064) ( Figs 19 –26). Carapace 11.73 long, 9.78 wide, chelicerae 6.23. Legs (femur, patella, tibia, metatarsus, tarsus, total): I: 11.08, 5.94, 9.57, 8.81, 5.74, 41.14. II: 10.47, 5.17, 7.80, 7.97, 4.77, 36.18. III: 8.74, 4.55, 7.18, 8.23, 4.95, 33.65. IV: 10.86, 4.99, 9.34, 11.69, 4.63, 41.51. Palp: 5.54, 3.85, 5.54, –, 2.27, 18.71. Midwidths: femora I–IV = 1.79, 1.83, 2.36, 1.68, palp = 1.13; patellae I–IV = 1.90, 1.94, 1.86, 1.80, palp=1.45; tibiae I–IV = 1.58, 1.45, 1.45, 1.34, palp = 1.82; metatarsi I–IV = 1.14, 1.07, 1.01, 0.99; tarsi I–IV = 1.19, 1.12, 1.05, 0.99, palp = 1.38. Abdomen 12.13 long, 8.92 wide. Spinnerets: PMS, 1.52 long, 0.57 wide, 0.87 apart; PLS, 2.60 basal, 1.90 middle, 2.23 distal; midwidths 0.94, 0.82, 0.63, respectively.

Carapace ( Fig. 19 ): 1.19 longer than wide; cephalic area moderately raised. Fovea: Slightly procurved, 1.28 wide. Eyes and eye tubercle: Tubercle 0.71 high, 1.35 long, 2.11 wide. Clypeus 0.14 wide. Sizes and inter-distances: AME 0.57, ALE 0.56, PME 0.32, PLE 0.51, AME–AME 0.20, AME–ALE 0.13, AME–PME 0.14, ALE–ALE 1.22, ALE–PME 0.30, PME–PME 0.83, PME–PLE 0.11, PLE–PLE 1.32, ALE–PLE 0.19, AME–PLE 0.38. Eye group 2.08 wide, 1.18 long. Maxillae: Length 3.51, width 2.11. Cuspules: ca. 120 spread over ventral inner heel. Labium: 1.51 long, 2.24 wide, with ca. 77 cuspules spaced by ca. one diameter from each other on the anterior third center (Fig. 20). Chelicerae: Basal segment with 11 teeth in row on promargin and denticles in basal area. Sternum: 5.31 long, 4.56 wide. Sigilla: first and second pairs rounded, third ovals (Fig. 20).

Legs: formula I= IV II III. Length leg IV to I: 1.01. Scopula: Tarsi I – IV fully scopulate. Metatarsi I – II fully scopulate; III 3 /5, IV 1 /5 distal. Metatarsus IV divided by row of 3–4 setae. Spination: palp: femur 0, patella 0, tibia p0-2-2; leg I: femur 0, patella 0, tibia v0-0-1ap, metatarsus v0-0-1ap; leg II: femur 0, patella 0, tibia v0-0-2ap, metatarsus v0-0-3ap; leg III: femur 0, patella 0, tibia v0-0-2ap, metatarsus v0-2-3ap; leg IV: femur 0, patella 0, tibia v1-1-2ap, metatarsus v14(4ap), r0-0-1. Spiniform setae on retrolateral maxillae. STC: a single row of 3–5 small teeth on legs I– II, IV, bare on leg III. Urticating setae: Only type I present, position and length range: LA, 0.40–0.45; LM, 0.41–0.46; MA, 0.39–0.54; MM, 0.63–0.67. Regions MP and LP are bald. Distribution of urticating setae on the abdomen dorsum unknown due to a large bald area .

Palp (Figs 21–23). Bulb pyriform, embolus slightly longer than tegulum length, slightly flattened at distal region, apex narrowing abruptly, forming a more or less straight distal portion. Prolateral keels present. PS forming embolus edge distally. PI reduced. Apex of the embolus broken, it is not possible to be certain about A keel. R present, not pronounced. SA absent. Bifid tibial spur (Figs 24–26) with two straight processes originating from common base, RP longest. A single, flattened, rhomboidal spine contiguous to the internal upper face of the RP. Metatarsus I curved at its basal third, when folded touches the retrolateral process laterally (Fig. 24).

Color pattern (in alcohol): Carapace and chelicerae brown. Legs 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 and ventrally yellowish brown, area with urticating setae dark. Femora, patellae, tibiae and metatarsi of legs and palp with very discrete light stripes. Apex of leg and palp segments with very discrete whitish rings on apex.

Redescription. Holotype female (Figs 28–29). Carapace 17.80 long, 13.62 wide, chelicerae 6.40. Legs (femur, patella, tibia, metatarsus, tarsus, total): I: 11.89, 6.75, 8.96, 8.61, 6.27, 42.48. II: 10.45, 5.79, 8.07, 6.91, 5.83, 37.05. III: 10.09, 6.07, 7.38, 8.01, 5.13, 36.68. IV: 12.76, 6.49, 11.09, 12.58, 6.26, 49.18. Palp: 8.45, 5.22, 6.33, –, 6.05, 26.08. Midwidths: femora I–IV = 2.07, 1.99, 2.58, 2.02, palp = 1.88; patellae I–IV = 2.84, 2.62, 2.79, 2.97, palp=2.47; tibiae I–IV = 2.51, 2.34, 2.66, 3.09, palp = 2.29; metatarsi I–IV = 2.04, 1.98, 1.94, 2.94; tarsi I–IV = 2.10, 1.93, 1.90, 1.96, palp = 2.11. Abdomen 28.77 long, 22.12 wide. Spinnerets: PMS, 2.25 long, 1.01 wide, 2.12 apart; PLS, 3.82 basal, 3.02 middle, 3.70 distal; midwidths 1.99, 1.33, 1.03, respectively.

Carapace: 1.30 longer than wide; cephalic area noticeably raised. Fovea: Straight, 4.81 wide. Eyes and eye tubercle: 2.29 long, 3.01 wide. Eye sizes and inter-distances: AME 0.42, ALE 0.69, PME 0.23, PLE 0.51, AME– AME 0.44, AME–ALE 0.39, AME–PME 0.24, ALE–ALE 2.11, ALE–PME 0.55, PME–PME 1.76, PME–PLE 0.13, PLE–PLE 2.20, ALE–PLE 0.50, AME–PLE 0.63. Maxillae: Length 5.60, width 3.13. Cuspules: ca. 202 spread over ventral inner heel. Labium: 2.12 long, 3.38 wide, with 105 cuspules spaced by ca. one diameter from each other on the anterior third center. Chelicerae: Basal segment with 14 teeth on promargin and denticles on basal area. Sternum: 7.79 long, 6.28 wide. Sigilla: first pair barely visible, second rounded, third oval.

Legs: formula IV I II III. Length leg IV to leg I: 1.16. Scopula: Tarsi I – IV fully scopulate. Metatarsi I – II fully scopulate; III 1 /2, IV 1 /5 distal scopulate. Metatarsus IV divided by row of 3–4 setae. Spination: palp: femur p0- 0-1, patella 0, tibia v0-0-3ap, p0-1-1; leg I: femur p0-0-1, patella 0; tibia v0-0-2, p0-1-0, metatarsus v0-0-1ap; leg II: femur p0-0-1, patella 0, tibia v0-0-3ap, metatarsus v0-0-2ap, p0-1-0; leg III: femur r0-0-1, patella 0, tibia v0- 0-2ap, p0-1-1, r1-1-1, metatarsus v3-0-3ap, p1-0-1, r1-0-1; leg IV: femur r0-0-1, patella 0, tibia v1-1-3ap, r1-1-1, metatarsus v18(3ap), p1-0-1, r1-0-1. Spiniform setae on retrolateral coxae II and III and prolateral coxae I– IV. Tibia IV thickened, especially at the distal end, metatarsus IV thickened at base, tibia and metatarsus covered with stiffed setae (Fig. 29). Urticating setae: Type I only .

Spermathecae: Two short spermathecae separated by weakly sclerotized area, spermathecal stalk narrower than spermathecal bulb (Fig. 28).

Color pattern (in alcohol): As in male.

Distribution. Only known from two localities in Serra da Mantiqueira, southeastern Brazil, in the state of São Paulo ( Fig. 1 ).

Figures

FIGURE 1. Map of Brazil showing geographic records of Arboriticus gen. nov. species. Dots represent type localities, squares additional localities, and triangles correspond to records of undetermined collected specimens, which are likely undescribed species.

FIGURES 19─26. Arboriticus tarsicrassus comb. nov., male. 19, carapace and chelicerae, dorsal. 20, sternum, labium, maxillae, and coxae, ventral. (21–23) left palp bulb. 21, prolateral. 22, retrolateral. 23, dorsal. (24─26) left tibial apophysis. 24, retrolateral. 25, prolateral. 26, ventral. Scale bar = 1 mm.