Ibana svarnadvipa Dhiya’ulhaq & Benjamin, 2025

Dhiya'ulhaq, Naufal Urfi, Benjamin, Suresh P., Buchori, Damayanti, Hidayat, Purnama, Scheu, Stefan & Drescher, Jochen, 2025, Expanding the taxonomy of crab spiders (Araneae, Thomisidae) in Sumatra: a new genus, five new species, and regional records, ZooKeys 1241, pp. 205-246 : 205-246

Ibana svarnadvipa Dhiya’ulhaq & Benjamin sp. nov.

Figs 15 , 16 , 17

Epidius rubropictus Benjamin, 2011: 15, figs 5 I, 35 D, E (female from Sumatra only) [misidentification].

Type material.

Holotype. Indonesia – Jambi Province • 1 ♂; Batang Hari, Bajubang, Sungkai ; 01°50'58.7"S, 103°18'00.5"E; elev. 56 m; 5 Jun. 2013; J. Drescher leg.; canopy fogging in jungle rubber plantation; GOET 2013_HJ 3.2_AraThom 035 N_001 (to be transferred to MZB) . Paratype. Indonesia – Jambi Province • 1 ♂; same data as holotype; ZMH ZMH -A 0031854 (GOET 2013_HJ 3.2_AraThom 035 N_002) . • 1 ♀; Sarolangun, Air Hitam, Lubuk Kepayang ; 02°05'06.8"S, 102°47'20.9"E; elev. 70 m; 23 Jun. 2013; J. Drescher leg.; canopy fogging in rubber plantation; GOET 2013_BR 2.2_AraThom 035 N_001 (to be transferred to MZB) .

Diagnosis.

Males of Ibana svarnadvipa Dhiya’ulhaq & Benjamin , sp. nov., can be distinguished from Ibana gan Liu & S. Q. Li, 2022 and Ibana senagang Benjamin, 2014 by the slightly dorsally curved VTA (Figs 15 D, F , 17 B vs oblique with a flexed-back tip in I. senagang, Benjamin 2016 : fig. 3 A; absent in I. gan, Zhong, Zheng & Liu, 2022 : fig. 1 E – G) and roughly triangular conductor with long-tapering tip (Figs 15 E , 17 A vs triangular with abruptly narrowing tip in I. senagang ; absent in I. gan ). Females can be distinguished by the CO positioned at the posterior end of spermatheca (Fig. 17 C vs anterior to spermatheca in I. gan , at middle length of spermatheca in I. senagang Liu et al. 2022 : figs 2, 3; Benjamin 2016: fig. 3 B, C). Additionally, both sexes are rather uniformly coloured yellowish brown, with a pair of red stripes that cross the eye region (Figs 15 A – C , 16 A, B vs abdomen with a large, dark median band I. gan , red cephalic stripes absent in both I. gan and I. senagang ; Zhong, Zheng & Liu, 2022: figs 1 A, B, 2 A, B; Benjamin 2016: fig. 1 G).

Description.

Male (holotype 2013_HJ 3.2_AraThom 035 N_001; Figs 15 , 17 A ). Total length 3.54. Carapace length 1.56; width 1.51. Abdomen length 1.98; width 1.56. Diameter of eyes: AME 0.06; ALE 0.11; PLE 0.12; PME 0.09. Interdistances between eyes: AME – AME 0.07; AME – ALE 0.04; ALE – ALE 0.28; PME – PME 0.14; PME – PLE 0.12; ALE – PLE 0.11; AME – PME 0.19; PLE – PLE 0.53. Leg measurements: leg I 8.55 (2.21, 0.55, 2.45, 2.12, 1.22); leg II 8.95 (2.48, 0.54, 2.59, 2.10, 1.24); leg III 4.55 (1.38, 0.38, 1.26, 1.00, 0.53); leg IV 4.78 (1.47, 0.37, 1.33, 1.12, 0.49). Carapace pear shaped, yellow; cephalic region with a pair of diagonal red stripes that cross the ocular area; AER recurved; PER slightly recurved. Legs yellow, uniformly coloured. Abdomen oval, pale yellow. Palp (Figs 15 D – F , 17 A, B ): cymbium 1.5 × the length of tibia. Conductor subtriangular; distal part tapering. Embolus long, filiform. Tibia with three strong macrosetae, prolateral to the VTA. VTA slightly dorsally curved; tip rounded.

Female (paratype 2013_BR 2.2_AraThom 035 N_001; Figs 16 , 17 C, D ). Total length 3.14. Carapace length 1.52; width 1.52. Abdomen length 1.62; width 1.26. Diameter of eyes: AME 0.05; ALE 0.11; PLE 0.12; PME 0.08. Interdistances between eyes: AME – AME 0.08; AME – ALE 0.05; ALE – ALE 0.29; PME – PME 0.15; PME – PLE 0.13; ALE – PLE 0.11; AME – PME 0.19; PLE – PLE 0.55. Leg measurements: leg I 7.72 (2.13, 0.58, 2.28, 1.78, 0.95); leg II 7.86 (2.27, 0.57, 2.28, 1.71, 1.03); leg III 4.08 (1.27, 0.42, 1.05, 0.86, 0.48); leg IV 4.18 (1.39, 0.38, 1.13, 0.94, 0.34). Female habitus as in male, except the carapace and abdomen is slightly darker in colour. Epigynum (Figs 16 C – E , 17 C, D ): atrium longer than wide, posterior half bordered by a thin flap. CO hidden by aforementioned flap, positioned posterior to spermatheca. CD long, going around the inner side of spermatheca before joining at the anterior side. Spermatheca inverted pear-shaped. FD half of spermatheca length.

Etymology.

The specific epithet is taken from an ancient name for Sumatra, which is Sanskrit for ‘ island of gold’. Also referring to the colouration of the species in ethanol. Noun in apposition.

Distribution.

Indonesia (Sumatra: North Sumatra and Jambi Province) Fig. 29 .

Figures

Figure 15. Ibana svarnadvipa Dhiya’ulhaq & Benjamin, sp. nov., male (holotype 2013 _ HJ 3.2 _ AraThom 035 N _ 001) A, B habitus A dorsal view B ventral view C eye region, frontal view D – F left palp D prolateral view E ventral view F retrolateral view. Scale bars: 1 mm (A, B); 0.5 mm (C); 0.2 mm (D – F).

Figure 16. Ibana svarnadvipa Dhiya’ulhaq & Benjamin, sp. nov., female (paratype 2013 _ BR 2.2 _ AraThom 035 N _ 001) A, B habitus A dorsal view B ventral view C – E epigynum C ventral view D cleared, ventral view E cleared, dorsal view. Scale bars: 1 mm (A, B); 0.1 mm (C – E).

Figure 17. Ibana svarnadvipa Dhiya’ulhaq & Benjamin, sp. nov A, B male (holotype 2013 _ HJ 3.2 _ AraThom 035 N _ 001), left palp A ventral view B tibia, retrolateral view C, D female (paratype 013 _ BR 2.2 _ AraThom 035 N _ 001), epigynum C ventral view D dorsal view. Abbreviations: C = conductor; CD = copulatory duct; CO = copulatory opening; E = embolus; FD = fertilisation duct; MA = median apophysis; S = spermatheca; VTA = ventral tibial apophysis. Scale bars: 0.2 mm (A); 0.1 mm (B – D).

Figure 29. Distribution of examined Thomisidae species from the Epidius clade (sensu Benjamin, 2011) prior to the present study, as well as the sampling location of the current study in Jambi Province, Sumatra, Indonesia (green flag). The new genus and the five new species described in the present study are all from the same study location, i. e., a replicated plot design across lowland rainforest, ‘ jungle rubber’ (rubber agroforestry), and smallholder monoculture plantations of rubber and oil palm in Jambi’s lowlands (Drescher et al. 2016).