Chalcovietnamicus tikus, Dhiya’Ulhaq, 2025

Chalcovietnamicus tikus Dhiya’ulhaq sp. nov.

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Figs 1–4 View Fig View Fig View Fig View Fig

Diagnosis

Chalcovietnamicus tikus Dhiya’ulhaq sp. nov. belongs to the daiqini -group based on the dense covering with khaki setae on body and absence of flag-like embolic apophysis ( Yu et al. 2023). Within the daiqini - group, male C. tikus most resembles those of Chalcovietnamicus daiqini ( Prószyński & Deeleman-Reinhold, 2012) and Chalcovietnamicus marusiki Yu, Maddison & Zhang, 2023 by slender, curved embolus and finger-shaped RTA with rounded tip, but can be distinguished by retrolaterally-bending embolus and rounded tip of tegular lobe ( Fig. 2C, E View Fig vs embolus prolaterally-curving and tegular lobe tip prolaterally pointed in C. marusiki [ Yu et al. 2023: figs 51, 56]). Females are similar to those of C. marusiki by diagonally-aligned, kidney-shaped spermatheca, but can be distinguished in having sharply bent copulatory ducts ( Fig. 4B, D View Fig vs gently curved in C. marusiki [ Yu et al. 2023: fig. 59]) and abruptly narrowed accessory glands with wide bases (vs tapering in C. marusiki ).

Etymology

The specific epithet is taken from the Indonesian word ‘ tikus ’, meaning ‘mouse’ or ‘rat’, referring to the small size. Noun in apposition.

Material examined

Holotype

INDONESIA – Jambi Province • ♂; Sarolangun, Bukit Duabelas National Park ; 1°56′34.3″ S, 102°34′52.6″ E; elev. 85 m; 5 Oct. 2013; J. Drescher leg.; canopy fogging in rainforest; GOET 2013_ BF3.1_AraSalt018N_001 (to be transferred to MZB). GoogleMaps

Paratype

INDONESIA – Jambi Province • 1 ♀; Bajubang, Batang Hari, Bajubang , Pompa Air ; 1°49′33.3″ S, 103°17′38.1″ E; elev. 51 m; 14 May 201; J. Drescher leg.; canopy fogging in jungle rubber plantation; GOET 2013_HJ2.1_AraSalt018N_001 (to be transferred to MZB) GoogleMaps .

Description

Male ( Figs 1–2 View Fig View Fig )

MEASUREMENTS. Total length 3.74. Carapace length 2.02; width 1.67. Opisthosoma length 1.72; width 1.29. Diameter of eyes: AME 0.52; ALE 0.25; PLE 0.21. Interdistances between eyes: ALE–ALE 1.07; ALE–PLE 0.70; PLE–PLE 1.22. Clypeus height 0.13. Leg measurements: leg I 4.19 (1.25, 0.80, 1.04, 0.69, 0.41); leg II 2.77 (0.91, 0.43, 0.55, 0.57, 0.31); leg III 2.91 (0.94, 0.36, 0.60, 0.63, 0.38); leg IV 2.86 (0.94, 0.37, 0.65, 0.58, 0.32).

HABITUS AND COLORATION. Carapace reddish-brown, covered with cream-colored setae. Chelicerae colored darker than carapace; dentition: one promarginal, one bicuspid retromarginal. Opisthosoma oval; dorsally covered in light-brown scutum, as well as faint stripe in middle and one pair of dark zig-zag patterns on side; ventral side of opisthosoma pale, posterior half with dark patch; spinnerets surrounded by dark circle. Leg I stouter than other legs; femur to tibia uniformly colored and slightly darker than carapace; tarsus pale. Legs II–IV with alternating dark and pale color. Spinnerets basally brown, distally pale.

PALP ( Fig. 2 View Fig ). Tibia length-to-width ratio 1.25. RTA finger shaped; apex rounded; almost as long as palpal tibia and forming a 70 degrees angle towards it. Cymbium elongated. Cymbial process present. Tegular lobe wide, tip rounded. Embolus arising at 11:30 position, approximately third of palpal bulb length, retrolaterally bent at distal third.

Female ( Figs 3–4 View Fig View Fig )

MEASUREMENTS. Total length 3.89. Carapace length 1.79; width 1.47. Opisthosoma length 2.10; width 1.59. Diameter of eyes: AME 0.39; ALE 0.24; PLE 0.16. Interdistances between eyes: ALE–ALE 1.09; ALE–PLE 0.56; PLE–PLE 0.85. Clypeus height 0.05. Leg measurements: leg I 2.35 (0.74, 0.35, 0.51, 0.41, 0.34); leg II 2.05 (0.66, 0.32, 0.41, 0.38, 0.28); leg III 2.34 (0.80, 0.34, 0.42, 0.48, 0.30); leg IV 2.55 (0.83, 0.27, 0.56, 0.55, 0.34).

HABITUS AND COLORATION. Female habitus as in male, except following: leg I only slightly thicker than other legs and similarly striated; margins of sternum almost smooth; abdominal scutum absent, dark abdominal pattern more pronounced.

EPIGYNUM ( Fig. 4 View Fig ). Epigynal plate rectangular, slightly longer than wide. Copulatory openings oval; diameter one of fourth spermathecal length; spaced 1.5 diameter apart. Copulatory ducts as long as spermathecae, acutely bent at latter third. Spermathecae kidney shaped, slightly longer than wide, diagonally oriented. Accessory glands with wide base, abruptly narrowed in middle. Fertilisation ducts one-fourth length of spermatheca.

Distribution

Sumatra: Jambi Province.

Natural history

All specimens were collected by canopy fogging in rainforests and jungle rubber plantations and are considered arboreal.