Taksinus bambus Songsangchote, Sippawat, Khaikaew & Chomphuphuang, 2022

Songsangchote, Chaowalit, Sippawat, Zongtum, Khaikaew, Wuttikrai & Chomphuphuang, Narin, 2022, A new genus of bamboo culm tarantula from Thailand (Araneae, Mygalomorphae, Theraphosidae), ZooKeys 1080, pp. 1-19 : 1

Taksinus bambus Songsangchote, Sippawat, Khaikaew & Chomphuphuang sp. nov.

Figures 1 , 3 , 4 , 5A-E , 6 , 7 , 8

Type material.

Thailand • Holotype 1 ♂ (TAK1); Mae Tho, Mueang Tak district, Tak province. Paratype 2 ♀ (TAK 2-3 ♀); the same data as the holotype. Specimens were deposited at ENTOKKU (holotype TAK1 ♂ and paratype TAK2 ♀ ID: ENTOKKU TAK1-2) and THNHM (paratype TAK3 ♀ ID: THNHM-Ar-00005).

Diagnosis.

Same as for the genus.

Etymology.

The species name bambus refers to the species, which was discovered in a bamboo plantation and lives in Asian bamboo stalks.

Description.

Male TAK1 holotype (ENTOKKU): color in life: leg black, carapace brownish yellow. Total length (including chelicerae) 26.30 mm; cephalothorax 11.09 mm long, 7.62 mm wide, 4.40 mm high (caput); fovea 2.28 mm wide, straight, deep; cephalothorax brown, with a cover of short, whitish-yellow hairs dorsally, long whitish-yellow hairs on lateral margins; clypeus 0.23 mm; ocular tubercle 1.50 mm long, 2.59 mm wide. The anterior eye row slightly procurved and posterior row straight; eyes whitish, ALE oval and larger than the round AME; Eye sizes: AME, 0.45 mm; ALE, 0.88 mm; PLE, 0.48 mm; PME, 0.31 mm. Inter-eye distances: AME-AME, 0.62 mm; AME-ALE, 0.32 mm; AME-PME, 0.30 mm; ALE-ALE, 1.90 mm; ALE-PME, 0.34 mm; PME-PME, 1.40 mm; PME-PLE, 0.10 mm; PLE-PLE, 2.00 mm; and ALE-PLE, 0.32 mm. Chelicerae dark brown, 7.65 mm long, outer cheliceral face with short scopula edge with rows of orange-red setae, the lower surface of the outer cheliceral has five slightly curved plumose setae pads on the retrolateral chelicerae (Fig. 3A ). Maxillae reddish brown, 6.06 mm long, 3.49 mm wide with>155 cuspules, covered with orange-red setae on the prolateral surface; stridulation organ consisting of stout thorn-like spines with 11 in two rows (7.4 mm from below suture) and six in one row (1.9 mm from above suture) on the prolateral maxillae (Fig. 3B ). Labium brown, length 1.3 mm, width 2.0 mm, with>75 cuspules damaged and loss encompassing approximately 40% of the proximal edge (Fig. 3C ). Sternum dark brown, covered with two hair types: strong dark and soft white; 6.41 mm long, 4.38 mm wide with two pairs of ovoid sigillae present near the lateral margins opposing coxa II and III. Sigilla: anterior pair absent; median pair 0.40 mm long, 0.25 mm wide, close to the sternal margin; posterior pair 0.79 mm long, 0.36 mm wide, 0.66 mm from the sternal margin. Abdomen 10.89 mm long, 7.71 wide, dark gray, black thickly hirsute laterally and ventrally. Legs: Pat, Tib, Met, and Tar dark brown. Length of legs and palpal segments are shown in Table 1 , leg formula 1423. Spination: tibia II r 0-0-1 (apical), III r 0-0-2 (apical), metatarsus I v 0-0-1 (apical), II v 0-0-1 (apical), III d 0-0-1 (apical), v 0-0-1 (apical), IV d 0-0-1 (apical), v 0-0-3 (apical).

The male tibia I spur is present and lacks a single megaspine on the inside of the tibial apophyses (Fig. 4A-D ). Scopulae on metatarsi and tarsi I through IV, undivided. Tar I-IV with two claws; spinnerets covered with dark longer and thinner hairs; Posterior lateral spinnerets with three segments, basal 2.3 mm, median 1.5 mm, digitiform apical 3.0 mm; lateral median spinnerets with one segment 1.25 mm. Pedipalps reddish brown, covered with longer and thinner hairs; tibia swollen; cymbium with two lobes of light brown shaggy scopulae; bulb and embolus 1.76 mm long, dark reddish brown; palpal bulb ellipsoid and partly concave, 1.60 mm long, 1.63 mm wide; embolus moderately curved, rounded apex, with single retrolateral keel (Fig. 5A-E ).

Paratype ♀ TAK3: total length (including chelicerae) 30.82 mm; cephalothorax 13.43 mm long, 10.39 mm wide, 2.98 mm high (caput); fovea 1.28 mm wide, slightly procurved, deep; cephalothorax brown, covered with short whitish hairs dorsally, golden yellow to yellowish-brown long hairs on lateral margins (Fig. 6A ); clypeus 0.13 high; ocular tubercle 1.70 mm long, 2.92 mm wide. Anterior eyes with long hairs in front of AME and mid-posterior PME area; anterior eye row slightly procurved and posterior row straight. Eye sizes: AME, 0.45 mm; ALE, 0.71 mm; PLE, 0.54 mm; PME, 0.37 mm. Inter-eye distances: AME-AME mm, 0.47; AME-ALE, 0.41 mm; AME-PME, 0.25 mm; ALE-ALE, 1.75 mm; ALE-PME, 0.54 mm; PME-PME, 1.27 mm; PME-PLE, 0.66 mm; PLE-PLE, 1.57 mm; and ALE-PLE, 0.39 mm. Chelicerae dark brown, 6.78 mm long, outer cheliceral face with short scopula margin with rows of orange-red setae, outer cheliceral on the lower surface with five slightly curved pads of plumose setae on the retrolateral chelicerae. Maxillae reddish brown, 3.83 mm long, 2.10 mm wide with>183 cuspules, covered with orange-red setae on the prolateral surface, labium brown, length 1.51 mm, width 2.09 mm, with>125 cuspules covering approximately 40% of the proximal edge (Fig. 6D ). Sternum dark brown, covered with two types of hairs: strong dark and soft white; 5.89 mm long, 5.54 mm wide with two pairs of ovoid sigillae present near lateral margins opposite coxa II and III (Fig. 6B ). Sigilla: anterior pair absent; median pair 0.35 mm long, 0.27 mm wide, close to the sternal margin; posterior pair 0.75 mm long, 0.32 mm wide, 0.72 mm from the sternal margin. Abdomen 15.58 mm long, 10.95 mm wide, dark gray and black thickly hirsute laterally and ventrally. Legs: Pat, Tib, Met, and Tar dark brown. Length of legs, palpal segments, and the comparative leg measurements are shown in Table 2 , leg formula 4123. Spination: tibia palp r 0-0-1 (apical), p 0-0-1 (apical), r 0-0-2 (apical), I p 0-0-1 (apical), II p 0-0-1 (apical), r 0-0-1 (apical), III p 0-0-1 (apical), IV r 0-0-1 (apical), p 0-0-1 (apical), metatarsus I v 0-0-1 (apical), II v 0-0-1 (apical), III d 0-0-1 (apical), v 0-0-1 (apical), p 0-0-1 (apical), r 0-0-2 (apical), IV v 0-0-3 (apical). Scopulae on metatarsi and tarsi I through IV undivided. Tar I-IV with two claws; spinnerets covered with dark brown longer and thinner hairs; posterior lateral spinnerets with three segments, basal 2.03 mm, median 1.40 mm, digitiform apical 2.10 mm; lateral median spinnerets with one segment 1.21 mm. Spermathecae (Fig. 7F ): paired and divided with fused in base, base 0.88 mm (left) and 1.00 mm (right) long, 1.10 mm (left) and 1.06 mm (right) wide; sclerotization heaviest apically, gradually decreasing basally.

Description.

Paratype ♀ TAK2: dark brown, carapace brown. Total length (including chelicerae) 34.80 mm; cephalothorax 14.39 mm long, 11.57 mm wide, 3.16 mm high (caput); fovea 1.20 mm wide, straight, deep; cephalothorax brown, covered with short whitish hairs dorsally, golden yellow to yellowish-brown long hairs on lateral margins; clypeus 0.15 mm high; ocular tubercle 1.83 mm long, 2.70 mm wide. Anterior eyes with long hairs in front of AME and mid-posterior PME area; anterior eye row slightly procurved and posterior row straight. Eyes whitish, ALEs oval in shape, larger than the round AMEs. Eye sizes: AME, 0.44 mm; ALE, 0.69 mm; PLE, 0.59 mm; PME, 0.40 mm. Inter-eye distances: AME-AME, 0.37 mm; AME-ALE, 0.49 mm; AME-PME, 0.30 mm; ALE-ALE, 1.69 mm; ALE-PME, 0.68 mm; PME-PME, 1.20 mm; PME-PLE, 0.17 mm; PLE-PLE, 1.86 mm; and ALE-PLE, 0.50 mm. Chelicerae dark brown, 7.02 mm long, outer cheliceral face with short scopula margin with rows of orange-red setae; outer cheliceral on the lower surface with five slightly curved pad of plumose setae on the retrolateral chelicerae (Fig. 7B, C ) with cheliceral needle form strikers (Fig. 7B, D ). Maxillae reddish brown, 3.64 mm long, 2.21 mm wide with 149 cuspules, covered with orange-red setae on the prolateral surface, stridulation organ consisting of stout thorn-like spines with 10 in two rows (7.4 mm from below suture) and six in one row (3.0 mm from above suture) on the prolateral maxillae (Fig. 6C ). Labium brown, length 2.29 mm, width 1.45 mm, with>7 cuspules damaged and lost. Sternum dark brown, covered with two types of hairs: strong dark and soft white; 6.22 mm long, 5.33 mm wide, with two pairs of ovoid sigillae present near the lateral margins opposite coxa II and III. Sigilla: anterior pair absent; median pair 0.51 mm long, 0.26 mm wide, close to the sternal margin; posterior pair 0.73 mm long, 0.32 mm wide, 0.45 mm from the sternal margin. Abdomen 18.72 mm long, 11.42 mm wide, dark gray and black thickly hirsute laterally and ventrally. Legs: Pat, Tib, Met, and Tar dark brown. Length of legs, palpal segments, and the comparative leg measurements are shown in Table 3 , leg formula 4123. Spination: tibia palp r 0-0-1 (apical), p 0-0-1 (apical), r 0-0-2 (apical), I p 0-0-1 (apical), II p 0-0-1 (apical), r 0-0-1 (apical), III p 0-0-1 (apical), IV r 0-0-2 (apical), p 0-0-1 (apical), metatarsus I v 0-0-1 (apical), II v 0-0-1 (apical), III v 0-0-1 (apical), p 0-0-1 (apical), r 0-0-2 (apical), IV v 0-0-3 (apical). Scopulae on metatarsi and tarsi I through IV, undivided. Tar I-IV with two claws; spinnerets covered with dark longer and thinner hairs; posterior lateral spinnerets with three segments; basal 2.10 mm, median 1.36 mm, digitiform apical 2.19 mm; lateral median spinnerets with one segment 1.34 mm. Spermathecae (Fig. 7E ): paired and divided with fused in base, base 0.90 mm (left) and 1.07 mm (right) long, 1.09 mm (left) and 1.17 mm (right) wide; sclerotization heaviest apically, gradually decreasing basally.

Distribution and natural history.

Specimens were collected from villages surrounding Tak province at approximately 1,000 m elevation. The biotope consists of a mixed deciduous forest dominated by bamboo that is rarely disturbed by human activity (Fig. 8A ). The new arboreal tarantula shows a surprising specialization in that it lives in the stalks of Asian bamboo ( Gigantochloa sp.) (Fig. 8B-E ). All specimens were collected from bamboo internodes in mature culms, having nest entrances approximately 2-3 cm within a silk-lined tubular burrow at the entrance located in the branch stub or at the middle of the bamboo culms. Some specimens had a secondary entrance without silk at the hole (Fig. 8B ). Tarantulas do not bore bamboo stems; instead, they depend on the assistance of other animals. Bamboo is attacked by numerous animals, the most common of which are insects from the orders Coleoptera , Lepidoptera , and Diptera ( Varma and Sajeev 2015). Furthermore, we hypothesized that the tarantula might occupy the empty nest of insects, such as the bamboo-nesting carpenter bee Xylocopa , which creates a large hole. All the tarantulas living in the bamboo culms build silken retreat tubes that cover the stem cavity (Fig. 8C-E ).

Figures

Figure 1. Taksinus bambus sp. nov. paratype ♀, TAK 2 A dorsal view B habitat in bamboo culm.

Figure 3. Taksinus bambus sp. nov. Holotype ♂ TAK 1 A chelicerae, retrolateral view B maxilla, prolateral view C palpi, labium, maxilla, and coxae, ventral view. Scale bars: 1 mm.

Figure 4. Taksinus bambus sp. nov. Holotype ♂ TAK 1. Tibial apophysis A ventral view B apical view C prolateral view D dorsal view. Scale bars: 1 mm.

Figures 5. Taksinus bambus sp. nov. holotype ♂ TAK 1 (A-E) and Omothymus sp. ♂ (F-J). Palpal bulb A prolateral view B retrolateral view C dorsal view D ventral view E apical view F prolateral view G retrolateral view H dorsal view I ventral view J apical view. Scale bars: 1 mm.

Figure 6. Taksinus bambus sp. nov. Paratype ♀ TAK 3 (A, B, D) Paratype ♀ TAK 2 (C). A carapace, dorsal view B sternum, labium, maxilla, and coxae, ventral view C maxilla, prolateral view D maxillae and labium with cuspules. Scale bars: 1 mm.

Figures 7. Taksinus bambus sp. nov. paratype ♀ TAK 2 (A-E) paratype ♀ TAK 3 (F). A chelicerae, prolateral view B chelicerae, retrolateral view C plumose hairs outer chelicerae, retrolateral view D chelicerae strikers, retrolateral view E spermathecae, dorsal view F spermathecae, dorsal view. Scale bars: 1 mm.

Figures 8. Taksinus bambus sp. nov. from Tak province, Thailand A biotope, bamboo forests in mountainous slope areas B tarantula habitat in bamboo culm with entrance hole (below) and secondary entrance (upper) C, D tarantula in bamboo culm E tarantula building silk tube retreats on the cover culm F paratype ♀, TAK 3 T. bambus alive.