Nyctimus mutilloides 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 mutilloides Benjamin & Dhiya’ulhaq sp. nov.

Fig. 8

Etymology.

The specific epithet is derived from the latin name of the velvet ant family Mutillidae , and the Greek-derived suffix - oides, meaning “ resembling ” or “ like. ” Thus, mutilloides translates to “ mutillid-like, ” referring to the spider’s striking abdominal patterns resembling abdominal markings of certain trogaspidiine mutillids.

Type material.

Holotype. Malaysia – Sabah State • ♂; Kinabalu National Park, Poring Hot Springs ; 05°59'N, 116°42’E; elev. 600–700 m; 9 Feb. 1997; A. Floren leg.; canopy fogging; RMNH RMNH.ARA.17882 .

Diagnosis.

Nyctimus mutilloides , sp. nov., can be readily distinguished from its congeners by its vivid white markings on the opisthosoma, forming a pattern highly suggestive of mutillid wasps (spots on all congeners). Furthermore, the male palp has a claw-shaped embolus that juts out from the distal margin of the bulb (different in other congeners; Fig. 8 B, C ).

Description.

Male ( holotype RMNH.ARA.17882 ; Fig. 8 ). Total length 2.80. Prosoma length 1.22; width 1.23. Opisthosoma length 1.57; width 1.22. Diameter of eyes: AME 0.07; ALE 0.12; PLE 0.10; PME 0.08. Interdistances between eyes: AME – AME 0.16; AME – ALE 0.11; ALE – ALE 0.39; PME – PME 0.2; PME – PLE 0.18; ALE – PLE 0.10; AME – PME 0.07; PLE – PLE 0.69. Prosoma cuboid, almost as long as wide, slightly flattened, weakly granulated, dark brown with darker margins, laterally adorned with long macrosetae; cephalic region elevated. Legs slender, pale yellow with indistinct annulations. No conspicuous spines observed. Opisthosoma oval, dorsoventrally flattened, with white spots and bands on black background.

Palp (Fig. 8 B, C ): cymbium slender, oval; tip rounded. Embolus claw-shaped, curved with a pointed tip, emerging distally from the tegulum. Tegulum oval; tegular hood wide, located retrolaterally near the base. RTA bilobed; both lobes roughly triangular; dorsal lobe with a serrated edge. VTA short, thumb-shaped, and slightly curved.

Female. Unknown.

Distribution.

Known only from the type locality ( Malaysia: Borneo: Sabah) (Fig. 19 ).

Remarks.

The white dots and stripes on the opisthosoma of N. mutilloides are reminiscent of those of mutillid wasps, especially those of the tribe Trogaspidiini (see figs 26–37 in Okayasu 2023). Whether this constitutes a form of Batesian mimicry is unclear, but it is possible given that certain Gnaphosidae , Salticidae , and Clubionidae seem to mimic velvet ants ( Nentwig 2008). Its presence in canopy fogging samples indicates an arboreal lifestyle, a noteworthy ecological trait within the genus. Further surveys and molecular data could shed light on its placement within Nyctimus and potential mimicry evolution in this group.

Figures

Figure 8. Nyctimus mutilloides Benjamin & Dhiya’ulhaq, sp. nov., male holotype (RMNH. ARA. 17882). A. Habitus, dorsal view; B. Left palp ventral view; C. Left palp 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 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).