Chilobrachys natanicharum Chomphuphuang, Sippawat, Sriranan, Piyatrakulchai & Songsangchote, 2023

Chomphuphuang, Narin, Sippawat, Zongtum, Sriranan, Patipan, Piyatrakulchai, Paveen & Songsangchote, Chaowalit, 2023, A new electric-blue tarantula species of the genus Chilobrachys Karsh, 1892 from Thailand (Araneae, Mygalomorphae, Theraphosidae), ZooKeys 1180, pp. 105-128 : 105

Chilobrachys natanicharum Chomphuphuang, Sippawat, Sriranan, Piyatrakulchai & Songsangchote sp. nov.

Figs 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 14A-D

Type materials.

Holotype 1 ♂ (THNHM-At-00000062), Paratype 1 ♀ (THNHM-At-00000063), deposited at THNHM, Thailand: Phang-Nga: Bang Nai Si, Takua Pa District, elevation 5 m, 19 Nov. 2022. Paratype 1 ♂ (ELB02), 2 ♀ (ELB03-04) deposited at ENTOKKU, Thailand: Phang-Nga: Khuekkhak, Takua Pa District, elevation 57 m, 20 Nov. 2022.

Diagnosis.

C. natanicharum sp. nov. was included in Chilobrachys based on the maxillary lyra of the stridulation organ comprising 1-3 rows of heavy claviform bacillae ( West et al. 2012). The male of C. natanicharum sp. nov. can be distinguished from C. dominus , C. hardwickei , C. himalayensis , C. hubei , C. jonitriantisvansickleae , C. liboensis , C. lubricus , and C. qishuoi , by the wide base of the embolus, which is flat and knife-like in shape (Figs 6 - 9 ) (long and slender in all other known congeners). Chilobrachys natanicharum sp. nov. similar to those of C. dominus , C. guangxiensis , C. hubei , C. jinchengi , C. liboensis , C. lubricus , and C. qishuoi , in having developed apical (A), prolateral inferior (PI), and prolateral superior keels (PS), but it can be distinguished by the presence of parallel longitudinal keels of PI and PS on the distal spine of the embolus (Fig. 8A, C ) (not parallel on the distal spine in other species) and the appearance of a groove at the beginning tip of the apical keel (Fig. 9A, B ). The males of C. natanicharum sp. nov. can be further distinguished from those of C. dominus by the angle between the lowest and highest points of the embolus (ALH), which is 40° (Fig. 14A-D ) (compared to 90° in C. dominus ). Females of C. natanicharum sp. nov. resemble C. fimbriatus in the form of the spermathecae, which have fused spermathecae. However, they can be distinguished from C. fimbriatus by the shape of the spermathecae. In C. natanicharum sp. nov., the spermathecae are raised and trapezoidal, with a thick, rounded upper edge (Fig. 12A, B ). On the other hand, C. fimbriatus has M-shaped spermathecae, characterized by a shallow hump and a middle hollow (see West et al. 2012: fig. 30). Females of this species can be distinguished from several other species, namely C. assamensis , C. dyscolus , C. guangxiensis , C. hardwickei , C. hubei , C. huahini , C. jonitriantisvansickleae , C. khasiensis , C. lubricus , C. nitelinus , C. paviei , C. qishuoi , C. sericeus , and C. stridulans , by the presence of two separate spermathecae receptacles. Chilobrachys natanicharum sp. nov. differs from all other Chilobrachys species, except C. jonitriantisvansickleae Nanayakkara, Sumanapala & Kirk, 2019, in that female and male juveniles have a metallic color on the legs, carapace, and chelicerae. The new specieds differs from C. jonitriantisvansickleae in terms of color shades. Chilobrachys natanicharum sp. nov. shows a violet-blue metallic color (Fig. 1 ), whereas C. jonitriantisvansickleae has a shade of metallic grayish-turquoise-blue sheen ( Nanayakkara et al. 2019: fig. 1a).

Etymology.

Chilobrachys natanicharum sp. nov. The specific epithet for this species was provided by Nichada Properties Co., Ltd, Thailand, the winner of the auction campaign for choosing the scientific name of the new species. The name is a combination of the names of Mr Natakorn Changrew and Ms Nichada Changrew, who are company executives. All proceeds from the auction were donated to support the education of Lahu children in Thailand and poor cancer patients. The Lahu people are an indigenous hill tribe in northern Thailand (Musoe) and are known for their vibrant culture and traditional way of life. Unfortunately, many Lahu children are denied access to education due to poverty, leaving them with limited opportunities for their future. The goal is to help change this by providing educational opportunities for Lahu children, giving them a chance to break out of the cycle of poverty. Additionally, cancer remains a significant public health issue globally, affecting millions of people each year. Many cancer patients struggle with financial hardship, which can make accessing quality care even more difficult. We believe that everyone deserves access to quality healthcare, regardless of their financial situation.

Description.

Male. Holotype ♂ THNHM-At-00000062: total length 38.51 (including chelicerae); carapace 14.08 wide, 15.17 long, 4.94 high; procurved deep fovea (Fig. 4F ), 2.17 wide; carapace black, covered with short, brownish-gray hairs dorsally and on lateral margins; ocular tubercle (Fig. 4D ) 2.74 wide, 1.53 long; clypeus absent. Posterior eye row slightly recurved, anterior eye row slightly procurved; eyes whitish, ALE larger than the round AME; eye size: AME, 0.56; ALE, 0.78; PLE, 0.52; and PME, 0.49. Eye interdistances: PME-PME 1.39; PME-PLE 0.20; PLE-PLE 2.02; ALE-PLE 0.29; ALE-PME 0.38; ALE-ALE 1.74; AME-PME 0.26; AME-AME 0.41; and AME-ALE 0.26; chelicerae dark brown, 8.70 long, 5.87 wide, covered with short, brownish-gray, violet, and metallic-blue hairs dorsally, ventrally covered with long, red-orange setae (Fig. 4A, B ), a series of strikers spiniform>4 horizontal rows (Fig. 4C ). Maxilla brownish orange, 3.12 wide, 6.65 long, with 275 cuspules, covered with orange-red setae on prolateral surface with the stridulating lyra. The stridulating lyra consists of three types (Fig. 5A ): first, a clavate or club-shaped lyra bent and with expanded end (largest part) (Fig. 5B ); second, a paddle-like lyra (Fig. 5C ); and third, a lyra with a dense covering of lance-shaped setae (Fig. 5D ). Labium dark brown, 3.03 wide, 2.04 long, with 634 cuspules. Sternum dark brown, 6.25 wide, 7.34 long, with soft, white hairs and strong, dark hairs, with two pairs of sigillae. Sigilla: anterior pair absent; median pair present, 0.18 wide, 0.56 long, 0.56 from sternal margin of coxa II; posterior pair present, 0.36 wide, 1.04 long, 1.00 from sternal margin of coxa II (Fig. 4E ).

Legs dark gray, femur covered with dark hair; prolateral femora I and II covered with violet and metallic-blue hairs. Coxa trochanter and patella dark gray, covered with brownish gray hairs; prolateral patella I and II covered with violet and metallic-blue hairs. Tibia covered with whitish gray hairs; prolateral tibia I and II covered with violet and metallic-blue hairs basally. Metatarsus and tarsus dark gray, covered with short and long, dark-gray hairs (Fig. 1B ). The spination (the total number of spines) is expressed for the basal, median, and distal regions on each side: metatarsus I ventral 0-0-1 (apical), metatarsus II ventral 0-0-3 (apical), metatarsus III ventral 0-0-2 (apical), metatarsus IV ventral 0-0-2 (apical), metatarsus IV prolateral 0-0-1. Length of leg and palp segment shown in Table 1 . Tibial apophysis absent. Tarsi I-III with two claws and tarsus IV with three claws; two teeth present on claws of tarsi I-III. Scopula undivided on metatarsi II and III, divided on metatarsi I and IV, and divided on tarsi I-IV. Pedipalps dark gray, covered with both long and short, grayish-white hairs on patella and tibia. Pedipalps covered with two hair types: short and dark, and long and brownish gray (Fig. 6A-C ).

Abdomen dark brown, 11.46 wide, 17.15 long; abdomen covered with short and long, brownish-gray hirsute dorsally, ventrally, and laterally. Spinnerets dark brown, covered with dark-brown hairs; lateral median spinnerets with one segment 1.60 long; posterior lateral spinnerets with three segments, 7.67 long basal to apical (3.30, + 1.61, + 2.76).

Palp bulb and embolus (PBL+ELS) 8.02 long, dark reddish brown, palp bulb spherical and partly concave; palp bulb width (PBW) 4.28 and length (PBL) 2.59; embolus width (EW) 3.65 and length along a straight line with the bulb (ELS) 5.43; embolus length along the curve (ELC) 7.10 (Fig. 7A-E ). Embolus wide at base and flat, knife-like in shape. Ratios: ELS/PBL = 2.10, ELC/PBL = 2.74, ELC/EW = 1.95, EW/PBL = 1.41, and ELS/EW = 1.49. Palp bulb twisted at 40° angle between lowest and highest points of embolus (ALH) (Fig. 14A, B ). Distal spine of embolus with two parallel longitudinal keels, PI and PS (Fig. 8A, C ). Spical keel also features a noticeable groove at its starting tip (Fig. 9 ).

Male. Paratype ♂ ELB02: total length 55.75 (including chelicerae); carapace 18.14 wide, 20.55 long, 5.29 high; fovea procurved, deep, 2.05 wide; carapace black, covererd weith short, brownish-gray hairs dorsally and on lateral margins, ocular tubercle 2.18 wide, 3.35 long; clypeus absent. Posterior eye row slightly recurved and anterior eye row slightly procurved; eyes whitish; ALE larger than the round AME; eye sizes: AME, 0.56; ALE, 0.85; PLE, 0.59; and PME, 0.52. Eye interdistances: PME-PME 1.74; PME-PLE 0.13; PLE-PLE 2.65; ALE-PLE 0.24; ALE-PME 0.39; ALE-ALE 1.99; AME-PME 0.23; AME-AME 0.57; and AME-ALE 0.29. Chelicerae dark brown, 8.25 wide, 12.27 long, covered with short, brownish-gray, violet, and metallic-blue hairs dorsally; ventrally covered with long, red-orange setae. Maxilla brownish orange, 4.41 wide, 7.97 long, with 337 cuspules, covered with orange-red setae on prolateral surface and with three types of stridulating lyra: clavate, paddle-like, and dense, lance-shaped setae. Labium dark brown, 4.07 wide, 2.47 long, with 687 cuspules. Sternum dark brown, 7.53 wide, 9.60 long, with soft, white hairs and strong, dark hairs, with two pairs of sigillae. Sigilla: anterior pair absent; median pair 0.40 wide, 0.88 long present 0.50 from sternal margin of coxa II; posterior pair 0.36 wide, 0.98 long present 1.21 from sternal margin of coxa II.

Legs dark gray, femur covered with dark hair; prolateral femora I and II covered with violet and metallic-blue hairs. Coxa trochanter and patella dark gray; covered with brownish-gray hairs; prolateral patellae I and II covered with violet and metallic-blue hairs. Tibia covered with whitish-gray hairs; prolateral tibiae I and II covered with violet and metallic-blue hairs basally. Metatarsus and tarsus dark gray; covered with short and long, dark-gray hairs. Spination: metatarsus I ventral 0-0-1 (apical), metatarsus II ventral 0-0-3 (apical), metatarsus III ventral 0-0-2 (apical), metatarsus IV ventral 0-0-2 (apical), metatarsus IV prolateral 0-0-1. Length of leg and palp segments shown in Table 2 . Tibial apophysis absent. Tarsi I-III with two claws (Fig. 10A ) and tarsus IV with three claws (Fig. 10B ), two teeth present on claws on tarsi I-III. Scopula undivided on metatarsi II and III, divided on metatarsi I and IV; divided on tarsi I-IV. Pedipalps dark gray, covered with long and short, grayish-white hairs on patella and tibia. Pedipalps covered with two hair types: short and dark, and long and brownish gray.

Abdomen dark brown, 16.00 wide, 27.51 long, covered with short and long, brownish-gray hairs dorsally, ventrally, and laterally. Spinnerets dark brown, covered with dark-brown hairs; lateral median spinnerets with one segment, 2.85 long; posterior lateral spinnerets with three segments 13.84 long basal to apical (4.77, + 3.92, + 5.15).

Palp bulb and embolus (PBL+ELS) 4.03 long, dark reddish brown, palp bulb spherical and partly concave, width (PBW) 2.56, length (PBL) 1.36; embolus width (EW) 2.06, embolus length along a straight line with the bulb (ELS) 2.67, embolus length along the curve (ELC) 4.12. Embolus wide at base and with a flat, knife-like shape. Ratios: ELS/PBL = 1.96, ELC/PBL = 3.03, ELC/EW = 2.00, EW/PBL = 1.51, and ELS/EW = 1.30. Palp bulb twisted at angle of 40° between lowest and highest points of embolus (ALH). Distal spine of embolus presents two parallel longitudinal keels, PI and PS. Apical keel shows a groove at its starting tip.

Female. Paratype ♀ ELB03: total length 56.78 (including chelicerae); carapace 18.09 wide, 21.91 long, 7.98 high; fovea procurved, deep, 2.87 wide; carapace dark brown, covered with short, brownish-gray hairs dorsally and on lateral margins; metallic-blue and violet hairs present on front part of carapace (Fig. 11D ). Ocular tubercle 3.35 wide, 2.18 long (Fig. 11C ); clypeus absent. Posterior eye row slightly recurved and anterior eye row slightly procurved; eyes whitish, ALE larger than the round AME; eye size: AME, 0.67; ALE, 0.97; PLE, 0.63; and PME, 0.53. Eye interdistances: PME-PME 1.87; PME-PLE 0.22; PLE-PLE 2.72; ALE-PLE 0.34; ALE-PME 0.54; ALE-ALE 2.35; AME-PME 0.41; AME-AME 0.53; and AME-ALE 0.43. Chelicerae dark brown, 8.72 wide, 12.15 long, covered with short, brown hairs, violet and metallic-blue hairs present on dorsally, ventrally covered with long, red-orange setae (Fig. 11A, B ). Maxilla brownish orange (Fig. 11E ), 4.44 wide, 6.32 long, with 361 cuspules, covered with orange-red setae on prolateral surface with three types of stridulating lyra: clavate, paddle-like, and dense, lance-shaped setae (Fig. 11F ). Labium dark brown, 3.79 wide, 2.74 long, with 616 cuspules. Sternum dark brown, 7.81 wide, 8.54 long, with soft, white hairs and strong, dark hairs, with two pairs of sigillae. Sigilla: anterior pair absent; median pair 0.25 wide, 0.70 long present 0.99 from sternal margin of coxa II; posterior pair 0.35 wide, 1.06 long present 1.48 from sternal margin of coxa II.

Legs dark brown, covered with dark-brown hair; prolateral femur, patella, tibiae I and II covered with violet and metallic-blue hairs. Metatarsus and tarsus with violet and metallic-blue hairs absent (Fig. 1A ). Spination: metatarsus I ventral 0-0-1 (apical), metatarsus II ventral 0-0-3 (apical), metatarsus III ventral 0-0-2 (apical), metatarsus IV ventral 0-0-2 (apical), metatarsus IV prolateral 0-0-1. Lengths of leg and palp segments shown in Table 3 ; tarsi I-III with two claws and tarsus IV with three claws, two teeth present on claws of tarsi I-III. Scopula undivided on metatarsi II and III, divided on metatarsi I and IV; divided on tarsi I-IV (Fig. 10C ). Pedipalps dark brown, covered with long and short, dark-brown hairs; prolateral femur, patella, and tibia covered with violet and metallic-blue hairs.

Abdomen dark brown 18.44 wide, 27.72 long, covered with short and long, dark-brown hairs dorsally, ventrally, and laterally. Spinnerets dark brown, covered with dark-brown hairs; lateral median spinnerets with one segment, 3.31 long; posterior lateral spinnerets with three segments 12.75 long, basal to apical (4.94, + 3.45, + 4.36).

The spermathecae are fused and raised, appearing trapezoidal, with a thick, rounded upper edge; basal width 3.85, apical width 2.44, height 1.53.

Female. Paratype ♀ ELB04: Total length 67.55 (including chelicerae); carapace 24.37 wide, 29.21 long, 12.55 high; fovea procurved, deep, 4.66 wide; carapace dark brown, covered with short, brownish-gray hairs dorsally and on lateral margins; metallic-blue and violet hairs present on front part of carapace. Ocular tubercle 4.22 wide, 2.05 long; clypeus absent. Posterior eye row slightly recurved and anterior eye row slightly procurved; eyes whitish, ALE larger than the round AME; Eye size: AME, 0.69; ALE, 0.90; PLE, 0.76; and PME, 0.74. Eye interdistances: PME-PME 2.09; PME-PLE 0.21; PLE-PLE 3.24; ALE-PLE 0.40; ALE-PME 0.66; ALE-ALE 3.01; AME-PME 0.42; AME-AME 0.56; and AME-ALE 0.62. Chelicerae dark brown, 10.50 wide, 15.50 long, covered with short brown hairs, violet, and metallic-blue hairs present dorsally; ventrally covered with long, red-orange setae. Maxilla brownish orange, 4.88 wide, 11.02 long, with 311 cuspules, covered with orange-red setae on prolateral surface and with three types of stridulating lyra: clavate, paddle-like, and dense lance-shaped setae. Labium dark brown, 4.66 wide, 3.79 long, with 770 cuspules. Sternum dark brown, 9.64 wide, 11.61 long, with soft, white hairs and strong dark hairs, with two pairs of sigillae. Sigilla: anterior pair absent; median pair 0.42 wide, 0.91 long present 1.61 from sternal margin of coxa II; posterior pair 0.53 wide, 1.58 long present 1.61 from sternal margin of coxa II.

Legs dark brown, covered with dark-brown hair; prolateral femur, patella, tibiae I and II covered with violet and metallic-blue hairs. Metatarsus and tarsus violet, metallic-blue hairs absent. Spination: metatarsus I ventral 0-0-1 (apical), metatarsus II ventral 0-0-3 (apical), metatarsus III ventral 0-0-2 (apical), metatarsus IV ventral 0-0-2 (apical), metatarsus IV prolateral 0-0-1. Lengths of leg and palp segments as shown in Table 4 ; Tarsi I-III with two claws and tarsus IV with three claws, two teeth present on claws of tarsi I-III. Scopula undivided on metatarsi II and III, divided on metatarsi I and IV; divided on tarsi I-IV. Pedipalps dark brown, covered with long and short dark-brown hairs; prolateral femur, patella, and tibia covered with violet and metallic-blue hairs.

Abdomen dark brown, 16.81 wide, 30.34 long; covered with short and long dark-brown hairs dorsally, ventrally, and laterally. Spinnerets dark brown, covered with dark-brown hairs; lateral median spinnerets with one segment 3.36 long; posterior lateral spinnerets with three segments 14.23 long, basal to apical (4.55, + 3.71, + 5.97).

The spermathecae are fused and raised, appearing trapezoidal, with a thick, rounded upper edge (Fig. 12A ); basal width 8.30, apical width 4.39, height 3.46.

Figures

Figure 1. Chilobrachys natanicharum sp. nov. live A paratype ♀ ELB 03 B holotype ♂ THNHM-At- 00000062.

Figure 2. Chilobrachys natanicharum sp. nov. A type locality B habitat in the type locality of THNHM-At- 00000062: Bang Nai Si, Takua Pa District Phang-Nga, elevation 5 m C habitat in the type locality of ELB 02: Khuekkhak, Takua Pa District Phang-Nga, elevation 57 m D juvenile build asymmetric funnel webs live in tree holes.

Figure 3. Male palpal bulb measurements and terminology of Chilobrachys natanicharum sp. nov.

Figure 4. Chilobrachys natanicharum sp. nov. holotype ♂ THNHM-At- 00000062 A chelicerae, retrolateral view B chelicerae, prolateral view C chelicerae strikers, retrolateral view D ocular tubercle E labium, and sternum, ventral view F fovea. Scale bars: 1 mm.

Figure 5. Chilobrachys natanicharum sp. nov. holotype ♂ THNHM-At- 00000062 A maxilla, prolateral view B clavate lyra C paddle-like lyra D lance-shaped lyra. Scale bars: 1 mm (A); 0.1 mm (B-D).

Figure 6. Chilobrachys natanicharum sp. nov. holotype ♂ THNHM-At- 00000062 A retrolateral view B ventral view C prolateral view. Scale bars: 3 mm.

Figure 7. Chilobrachys natanicharum sp. nov. holotype ♂ THNHM-At- 00000062, palpal bulb A prolateral view B retrolateral view C dorsal view D ventral view E apical view. Scale bars: 1 mm.

Figure 8. Chilobrachys natanicharum sp. nov. holotype ♂ THNHM-At- 00000062, embolus A dorsal view B ventral view retrolateral view C prolateral-dorsal view. Abbreviations: A apical keel; PI prolateral inferior keel; PS prolateral superior keel; EO embolic opening. Scale bars: 1 mm.

Figure 9. Chilobrachys natanicharum sp. nov. holotype ♂ THNHM-At- 00000062, embolus A ventral view. B dorsal view. Abbreviations: A apical keel; G groove at starting tip of apical keel. Scale bars: 0.5 mm (A); 1 mm (B).

Figure 10. Chilobrachys natanicharum sp. nov. paratypes A claws of tarsus II, paratype ♂ ELB 02 B claws of tarsi IV with third claw, paratype ♂ ELB 02 C scopula on tarsus I, paratype ♀ ELB 03. Scale bars: 1 mm.

Figure 11. Chilobrachys natanicharum sp. nov. ♀ paratype ELB 03 A chelicerae, retrolateral view B chelicerae, prolateral view C ocular tubercle D fovea E labium and maxilla, ventral view F maxilla, prolateral view. Scale bars: 1 mm.

Figure 12. Chilobrachys natanicharum sp. nov. spermathecae, dorsal view A ♀ paratype ELB 04 B ♀ paratype THNHM-At- 00000063. Scale bars: 1 mm.

Figure 14. Angle of the lowest to highest point of the embolus (ALH) palpal bulb A Chilobrachys natanicharum sp. nov. holotype, THNHM-At- 00000062, ♂, retrolateral view B C. natanicharum sp. nov. holotype ♂ THNHM-At- 00000062, prolateral view C C. natanicharum sp. nov., ELB 02 ♂, retrolateral view D C. natanicharum sp. nov., ELB 02, prolateral view E Chilobrachys sp., SPT 151434011 ♂, prolateral view F Chilobrachys sp. SPT 151436013 ♂, prolateral view G Cyriopagopus minax non-type ♂, prolateral view H Cyriopagopus longipes non-type ♂, prolateral view I Taksinus bambus holotype ♂, prolateral view J Omothymus sp. OMS 01 ♂, prolateral view.