Aenigmarachne colombiana, Osorio & Ávila-Polo & Sabbatino & Suárez- Martínez, 2025

Aenigmarachne colombiana sp. nov.

( Figs 1–8 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 , 9B View FIGURE 9 )

Type material: Holotype male (ICN-Ar 13744), from COLOMBIA: Bolívar : Tiquisio, vda. Puerto Coca, hand collected, 8°29'20"N 74°19'18"W, 30 m. a.s.l., 20–23 December 2020, coll. L. Osorio. GoogleMaps Paratype (s): 2 females ( 1 female dissected) (ICN-Ar 13745), [same data as holotype] GoogleMaps ; 1 male (ICN-Ar 13746) [same data as holotype] December 2017, coll. L. Osorio GoogleMaps ; 1 female (ICN-Ar 13749) [same data as holotype] 21–25 June 2025, coll. L. Osorio GoogleMaps ; 1 male, 5 females (ICN-Ar 13750) [same data as holotype] 21–25 June 2025, coll. L. Osorio. GoogleMaps

Other material examined: 1 immature female (ICN-Ar 13747), 7 juvenile specimens (ICN-Ar 13748) from COLOMBIA: Bolívar : Tiquisio, vda. Puerto Coca, hand collected, 8°29'20"N 74°19'18"W, 30 m GoogleMaps .a.s.l., 20–23 December 2020, coll. L. Osorio.

Diagnosis: Males differ from those of A. sinapophysis by their shorter embolus and the more pronounced extension of the PS keel ( Figs 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 ), PS keel restricted to the apical region in A. sinapophysis ( Sherwood & Gabriel, 2020: figs 5–8). Additionally, the male palps differ by the presence of a PI and a PAc keels ( Figs 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 ), which are absent in A. sinapophysis (see Sherwood & Gabriel, 2020: figs 5–8).

Etymology: The specific epithet colombiana is an adjective that refers to the country where the type specimen was collected.

Description. Male holotype (ICN-Ar 13744). Total length including chelicerae 15.9; carapace length 6.4, width 5.4; caput slightly raised ( Fig. 1A View FIGURE 1 ); ocular tubercle raised, length 0.8, width 1.3. Eyes: ALE> PLE, PLE> AME, AME> PME, anterior row slightly procurved, posterior row recurved ( Fig. 1C View FIGURE 1 ); clypeus narrow; fovea deep, transverse, straight; chelicera length 3.5, width 1.7; opisthosoma length 6.0, width 4.0 ( Fig. 1B View FIGURE 1 ); maxilla with ca. 176 cuspules, covering ca. 36% of proximal edge ( Fig. 1D View FIGURE 1 ); labium length 1.1, width 1.3, with 34 labial cuspules ( Fig. 1D View FIGURE 1 ); labio-sternal mounds joined along entire base of labium; sternum length 3.1, width 2.8, with three pairs of sigilla ( Fig. 1D View FIGURE 1 ); tarsi I densely scopulate, tarsi II–IV divided by band of stout setae; metatarsal scopula: I 100%; II 50%; III 41%; IV ascopulate; lengths of leg and palpal segments see Table 1. Leg formula 4,1,2,3; spination: tibia I d 0–1–0, v 0–1–4 (3 apical) II d 1–0–1, v 0–1–1 (apical) III d 1–2–1, v 1–2–3 (apical) IV d 1–0–2, v 2–2–4 (3 apical), palp p 0–0–3, metatarsus I v 1–0–2 (apical), II v 1–0–3 (apical), III d 1–2–3 (1 apical), v 1–4–7 (5 apical), IV d 2–1–2, v 6–4–8 (4 apical); palpal tibia slightly incrassate with a low retrolateral nodule ( Fig. 5A–C View FIGURE 5 ); leg I without tibial apophyses; metatarsus I straight, basal or median nodule absent; femur III slightly incrassate, femur IV without a pad of plumose setae on retrolateral face, stridulation organ absent in all legs; posterior lateral spinnerets with three segments ( Fig. 1E View FIGURE 1 ): basal 1.4, medial 0.9, digitiform apical 1.3; posterior median spinnerets with one segment; palpal bulb with an elongate and thin embolus, tapering to its tip, with slight curvature at its basal third, small extent of separation between base of bulb and tegulum, PS and PI keels weakly developed, A keel present ( Figs 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 ). Urticating setae: only subtype I b present. Colour alive: body completely dark brown, with yellowish setae surrounding the carapace (As in Fig. 8B View FIGURE 8 ).

Description. Female paratype (ICN-Ar 13749). Total length including chelicerae: 32.4; carapace length 12.0, width 10.6; caput highly raised ( Fig. 6A View FIGURE 6 ); ocular tubercle raised, length 1.4, width 1.9. Eyes: ALE> PLE, PLE> AME, AME> PME, anterior row procurved, posterior row recurved ( Fig. 6C View FIGURE 6 ); clypeus wide; clypeal fringe long; fovea deep, transverse, procurved; chelicera length 4.7, width 3.7; opisthosoma length 15.7, width 10.1 ( Fig. 6B View FIGURE 6 ); maxilla with ca.179 cuspules, covering ca. 30% of proximal edge ( Fig. 6D View FIGURE 6 ); labium length 1.6, width 2.1, with 43 labial cuspules ( Fig. 6D View FIGURE 6 ); labio-sternal mounds joined along entire base of labium; sternum length 5.5, width 5.2, with three pairs of sigilla ( Fig. 6D View FIGURE 6 ); tarsi I–IV divided by band of stout setae which is wider on the posterior tarsi; metatarsal scopula: I 100%; II 50%; III 25%; IV ascopulate; lengths of leg and palpal segments see Table 2. Leg formula 4,1,2,3; spination: femur I d 0–0–1, II d 0–0–1, III d 0–0–1, IV d 0–0–1, patella III p 0–0–2, r 0–1–0, IV p 0–0–1, r 0–1–0, tibia II d 0–0–1, v 0–1–2 (apical) III p 1–1–1, r 1–1–1, v 1–2–3 (apical), IV p 1–1–0, r 1–2–1, v 3–2–4 (3 apical), palp v 0–0–4 (3 apical), metatarsus I v 0–0–2 (apical), II p 0–1–1, v 1–0–3 (apical), III d 0–0–2, p 1–2–0, v 0–1–2, v 2–3–5 (4 apical), IV p 1–1–1, r 1–2–1, v 9–6–9 (5 apical); femur III not incrassate, femur IV without pad of plumose setae on retrolateral face, stridulation organ absent from all legs; posterior lateral spinnerets with three segments: basal 2.2, medial 1.5, digitiform apical 1.8; posterior median spinnerets with one segment. Urticating setae: only subtype I e present. Spermathecae: consisting of two separate seminal receptacles with a wide base, narrow neck and extended apical lobes. Each seminal receptacle emerges from ovate guard plate ( Fig. 7 View FIGURE 7 ). Colour alive: prosoma and opisthosoma reddish brown with a dark grey pad of urticating setae ( Fig. 8A View FIGURE 8 ).

Distribution: Known only from the type locality, Puerto Coca, Tiquisio, Bolívar, Colombia ( Fig. 10 View FIGURE 10 ).

Natural History. Individuals of A. colombiana sp. nov. were found near residential areas, closely associated with human-built structures ( Fig. 9A View FIGURE 9 ). Juveniles of this species typically build shallow burrows under structures such as plastic, logs, or rocks. In contrast, females and some young males occupy burrows dug into the ground, with a variable depth ranging from 10 to 30 centimeters. The latter may have widened areas that form small chambers ( Fig. 9E View FIGURE 9 ). In none of the cases was silk observed covering the entrances or internal walls of the burrows ( Fig. 9C–D View FIGURE 9 ).

Although on several occasions, multiple individuals were found under the same structure, in captivity, they show cannibalistic tendencies when housed together. Juveniles and males tend to be “shy” and, when disturbed, quickly release a significant amount of urticating setae. In contrast, adult females are remarkably defensive, combining this defensive behaviour with displays of their chelicerae and, on occasion, exuding a drop of venom ( Fig. 9B View FIGURE 9 ).

Morphologically, juveniles of both sexes closely resemble adult females in terms of colour, while adult males acquire a dark brown colour ( Fig. 8 View FIGURE 8 ).

Ontogeny. Observations made on the individuals of A. colombiana sp. nov. revealed that the urticating setae (UrS) are distributed in the dorsal-posterior region of the opisthosoma following a uniform pattern. This pattern has also been reported by Bertani & Guadanucci (2013) in other Theraphosinae with type I UrS, which may exhibit one or two distribution patterns, in contrast to the genera with UrS of the type III, IV, or combinations of III+IV UrS, which show a greater variability in their distribution.

Throughout the different points in the ontogenetic development of A. colombiana sp. nov., changes in the length or angle of the UrS are negligible. Juveniles (both males and females) and adult females exclusively present

UrS of the I e subtype ( Fig. 6F View FIGURE 6 ), with no evidence of co-occurrence of other described types or subtypes. The only significant ontogenetic change related to the UrS in this species occurs during the transition from juvenile males to adults, where the setae subtype changes from I e to I b ( Table 3).

In other genera of the tribe Theraphosini, sensu Turner et al. (2018) , basic type I urticating setae are present from the earliest nymphal stages, while subtypes I a, I b, and/or I c only co-occur in advanced developmental stages (see Kaderka et al. 2019). However, exceptions to this pattern have been documented in two juveniles of Phormictopus spp. from the Dominican Republic, where the co-occurrence of basic type I with subtypes I a and I b was recorded ( Kaderka et al. 2019). In contrast, A. colombiana sp. nov. completely lacks basic type I setae in all its developmental stages.