Arboriticus minor 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 : 536-538

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

( Figs 1 , 38 –45, 85)

Gen. sp. 5; Bertani, 2023:14–15, 19, 23.

Diagnosis. Males resemble those of A. tarsicrassus gen. nov. comb. nov. and A. petropolis gen. nov. sp. nov. by the reduced male palpal bulb keels (Figs 40–42) in conjunction with the metatarsus I touching the RP of the tibial spur laterally when flexed. They can be distinguished from those of A. tarsicrassus gen. nov. comb. nov. and A. petropolis gen. nov. sp. nov. by the PP of tibial spur thickened and the RP approximately the same length as the PP (Figs 43–45). They can also be distinguished from all other species by the sternum being much longer than wide (Fig. 39).

Etymology. The specific epithet “minor ” is a Latin word for “small”, referring to the small size of the specimens of this species.

Type material. Holotype male from Brazil, state of São Paulo, Pilar do Sul [23º48’S, 47º43’W] 700 m a.s.l., without date and collector name, IBSP 157849 ; Paratype male from Brazil, state of São Paulo, Tapiraí [23º57’S, 47º30’W] 864 m a.s.l., without date and collector name, IBSP 11633 .

Description. Holotype male ( Figs 38 –45) IBSP 157849. Carapace 10.52 long, 8.45 wide, chelicerae 5.34. Legs (femur, patella, tibia, metatarsus, tarsus, total): I: 11.12, 5.23, 9.47, 7.83, 5.28, 38.93. II: 9.95, 4.48, 8.44, 7.34, 4.84, 35.05. III: 8.73, 4.07, 6.93, 8.38, 4.34, 32.35. IV: 10.27, 4.35, 9.50, 12.25, 4.93, 41.28. Palp: 6.48, 3.49, 5.07, –, 2.01, 17.05. Midwidths: femora I–IV = 1.78, 1.43, 2.06, 1.49, palp = 0.99; patellae I–IV = 1.74, 1.73, 1.53, 1.74, palp = 1.32; tibiae I–IV = 1.23, 1.20, 1.16, 1.19, palp = 1.41; metatarsi I–IV = 1.06, 0.98, 0.95, 0.94; tarsi I–IV = 1.04, 0.95, 0.94, 0.93, palp = 1.30. Abdomen 8.97 long, 6.49 wide. Spinnerets: PMS, 1.02 long, 0.41 wide, 0.60 apart; PLS, 1.71 basal, 1.10 middle, 2.04 distal; midwidths 0.79, 0.65, 0.54, respectively.

Carapace ( Fig. 38 ): 1.24 longer than wide; cephalic area moderately raised. Fovea: Straight, 1.86 wide. Eyes and eye tubercle: Tubercle 0.56 high, 1.10 long, 1.77 wide. Clypeus 0.09 wide. Sizes and inter-distances:AME 0.41, ALE, 0.58, PME 0.32, PLE 0.42, AME–AME 0.13, AME–ALE 0.11, AME–PME 0.09, ALE–ALE 0.92, ALE–PME 0.15, PME–PME 0.66, PME–PLE 0.08, PLE–PLE 1.17, ALE–PLE 0.16, AME–PLE 0.34. Eye group 1.75 wide, 0.91 long. Maxillae: Length 3.27, width 1.94. Cuspules ca. 145 spread over ventral inner heel. Labium: 1.29 long, 2.10 wide, with ca. 116 cuspules spaced by ca. one diameter from each other on the anterior third center (Fig. 39). Chelicerae: Basal segment with 12 teeth in row on promargin and denticles in basal area. Sternum: 5.62 long, 3.88 wide. Sigilla: first pair rounded, second and third ovals, all less than a diameter from margin (Fig. 39).

Legs: formula I= IV II III. Length leg IV to I: 1.06. Scopula: Tarsi I – IV fully scopulate, III with row of sparse setae, IV with three wide rows of conspicuous setae. Metatarsus I fully scopulate; II 2 /3, III 1 /2, IV 1 /5 distal scopulate. Metatarsus IV divided by row of 3–4 setae. Spination: palp: femur 0, patella p1; tibia p1-2-5(4ap), d0-0- 3ap; leg I: femur 0, patella 0, tibia v0-0-1ap, p1-0-0, metatarsus v0-0-1ap; leg II: femur 0, patella 0, tibia v0-0-2ap, metatarsus v0-1-3ap; leg III: femur 0, patella 0, tibia v0-1-2ap, p0-1-0, r0-1-0, metatarsus v3-1-3ap, p0-1-1, r0-1-1; leg IV: femur 0, patella 0, tibia v1-2-6(3ap), p0-1-0, r0-1-0, metatarsus v16(4ap), p1-0-1, r1-0-1. Some spiniform setae on retrolateral maxillae and coxae I– III; and, on prolateral coxae I– IV. STC: a single row of 4–7 small teeth on legs I– IV. Urticating setae: Only Type I present, position and size: MA, 0.37. Distribution of urticating setae on the abdomen dorsum unknown due to large bald area .

Palp (Figs 40–42). Bulb pyriform, embolus slightly longer than tegulum length, slightly flattened at distal region, apex narrowing abruptly, forming more or less straight distal portion. Prolateral keels present. PS and PI reduced. A keel short. R present, not pronounced. SA absent. Bifid tibial spur (Figs 43–45) reduced in size, with two convergent processes originating from a common base, both tapering distally, PP thickened. A single, flattened, rhomboidal spine contiguous to internal face of PP. Metatarsus I roughly straight, when folded touches retrolateral side of RP (Fig. 43).

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

Distribution. Known only from two nearby locations in the Serra do Mar and near the Vale do Ribeira, in the state of São Paulo, Southeastern Brazil ( 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 38─45. Arboriticus minor gen. nov. sp. nov., holotype male. 38, carapace and chelicerae, dorsal. 39, sternum, labium, maxillae, and coxae, ventral. (40–42) left palp bulb. 40, prolateral. 41, retrolateral. 42, dorsal. (43─45) left tibial apophysis. 43, retrolateral. 44, prolateral. 45, ventral. Scale bar = 1 mm.