Nyctimus falcatus Benjamin & Dhiya’ulhaq, 2025

Benjamin, Suresh P., Dhiya’ulhaq, Naufal Urfi, Deeleman-Reinhold, Christa, Buchori, Damayanti, Hidayat, Purnama, Scheu, Stefan & Drescher, Jochen, 2025, Taxonomic notes on the crab-spider genera Nyctimus Thorell, 1877 and Zametopina Simon, 1909 (Araneae, Thomisidae) with descriptions of six new species from Southeast Asia, ZooKeys 1255, pp. 95-125 : 95-125

Nyctimus falcatus Benjamin & Dhiya’ulhaq sp. nov.

Fig. 4

Etymology.

The species epithet falcatus is derived from the Latin word falx / falcis, meaning “ sickle ” or “ scythe. ” It refers to the distinctly curved, sickle-shaped embolus of the male palp, a diagnostic feature of the species.

Type material.

Holotype. Thailand – Phang Nga Province • ♂; Khao Lak National Park ; no more label data; RMNH RMNH.ARA.17861 .

Diagnosis.

Males are very similar to N. saksang sp. nov., in having a similar sickle-shaped embolus, but they can be easily distinguished from it by the large, digitiform VTA, attached distally on the RTA (the corresponding part in N. saksang , sp. nov., is much smaller and attached medially on the ventral lobe of RTA; Fig. 4 B vs Figs 16 C , 17 A ).

Description.

Male ( holotype RMNH.ARA.17861 ; Fig. 4 ). Total length: 2.36. Prosoma length 1.23; width: 1.05. Opisthosoma length 1.13; width 1.02. Diameter of eyes: AME 0.08; ALE 0.15; PLE 0.14; PME 0.05. Interdistances between eyes: AME – AME 0.27; AME – ALE 0.08; ALE – ALE 0.59; PME – PME 026; PME – PLE 0.27; ALE – PLE 0.18; AME – PME 0.14; PLE – PLE 0.79. Prosoma cuboid, almost as long as wide, dark reddish brown; surface weakly granulated; laterally adorned with long macrosetae, each arising from a small tubercle. Chelicerae and sternum coloured as prosoma. Front legs brown; back legs brown except for the white femora III and IV. Opisthosoma round, light brown; dorsally covered with scutum; five large sigillae present, arranged in a triangular formation.

Palp (Fig. 4 B, C ): cymbium oval. Embolus sickle-shaped. Tegulum round, with a small triangular projection next to the embolus; tegular hood small. RTA wide trapezoid; VTA large, digitiform, attached distally on the RTA.

Female. Unknown.

Distribution.

Only known from the type locality ( Thailand: Phang Nga) (Fig. 19 ).

Remarks.

The specimen is partially damaged: both first legs are broken and incomplete, and the remaining legs are mostly missing or fragmented.

Figures

Figure 4. Nyctimus falcatus Benjamin & Dhiya’ulhaq, sp. nov., male holotype (RMNH. ARA. 17861). A. Habitus, dorsal view; B. Left palp, ventral view; C. Left palpal tibia, retrolateral view. Abbreviations: E = embolus; RTA = retrolateral tibial apophysis; TH = tegular hood; VTA = ventral tibial apophysis. Scale bars: 0.5 mm (A); 0.2 mm (B, C).

Figure 16. Nyctimus saksang Dhiya’ulhaq & Benjamin, sp. nov. male holotype (AraThom 036 N 2013 HF 2.1 001). A. Habitus, dorsal view; B. Habitus, ventral view; C. Left palp, ventral view; D. Left palp, retrolateral view. Scale bars: 1 mm (A, B); 0.2 mm (C, D).

Figure 17. Nyctimus saksang Dhiya’ulhaq & Benjamin, sp. nov. male holotype (AraThom 036 N 2013 HF 2.1 001). A. Left palp, ventral view; B. Left palp, retrolateral view. Abbreviations: DL = dorsal lobe; E = embolus; ML = medial lobe; RTA = retrolateral tibial apophysis; TH = tegular hood; VTA = ventral tibial apophysis; VL = ventral lobe. Scale bar: 0.2 mm.

Figure 19. Distribution of all described Nyctimus and Zametopina (Araneae: Thomisidae) species. Grey circles surrounding white dots indicate species collected from the same or very closely located sampling points in Brunei, Sabah (Malaysia), and Jambi (Indonesia).