Utivarachna itiokai Yamasaki, 2023

Yamasaki, Takeshi, Hashimoto, Yoshiaki, Endo, Tomoji, Hyodo, Fujio, Itioka, Takao, Mohamed, Maryati & Meleng, Paulus, 2023, Taxonomic study of Bornean species of Utivarachna Kishida, 1940 (Araneae: Trachelidae), with the description of a new species, Zootaxa 5343 (1), pp. 55-73 : 56-58

Utivarachna itiokai Yamasaki sp. nov.

Figs 1–3

Type material. Holotype ♁ ( LMB _ TY20180829 _TR01, FRCS), Sungai Liku , Lambir Hills National Park, Sarawak, BORNEO, 29.VIII.2018, leg. T. Yamasaki.

Diagnosis. Utivarachna itiokai sp. nov. matches the following characteristics of the dusun -group: the carapace is truncated at the posterior end; each of the posterior eyes is evenly spaced; the RTA is well-sclerotized apically without membranous parts; the legs I and II bear rounded cusps ventrally except for their trochanters and coxae; the proximal part of metatarsus I is concave ventrally.

The males of U. itiokai sp. nov. are similar to those of U. dusun and U. rubra in the structures of the palp, but can be distinguished from the latter two species by the inclining orientation of the coils formed by the embolus: the plane of the embolus coils inclines retrolaterally and is covered by the cymbium in U. itiokai sp. nov., whereas the plane of the coils inclines dorsally in U. dusun and U. rubra .

Etymology. The specific name is given in honor of Dr. Takao Itioka (Kyoto University).

Measurements (holotype ♁). Carapace length 1.66; width 1.25. Cephalic width 0.90. Diameter of eyes: AME 0.10; ALE 0.11; PME 0.11; PLE 0.11. Interdistances between eyes: AME–AME 0.03; AME–ALE 0.03; ALE–ALE 0.30; PME–PME 0.10; PME–PLE 0.12; PLE–PLE 0.56; ALE–PLE 0.11; AME–PME 0.05. MOA: length 0.25; anterior width 0.25; posterior width 0.31. Clypeus height 0.18. Abdomen length 1.77; width 1.25. Legs: I 4.32 (1.38, 0.61, 1.06, 0.71, 0.56); II 3.47 (1.00, 0.45, 0.76, 0.76, 0.50); III 2.67 (0.78, 0.37, 0.52, 0.65, 0.35); IV 3.32 (0.91, 0.40, 0.75, 0.86, 0.40).

Male ( Fig. 1A–E ). Carapace oval and superficially granulated, with truncated posterior end. Thoracic lateral margins hardly undulating. PER longer than AER, slightly recurved. Fovea shallow, indistinct. Ventral clypeus margin with small truncated projection between chelicerae. Chelicerae superficially granulated, with three teeth on each prolateral and retrolateral margin. Pedicel short. Abdomen oval; entire dorsum covered by sclerotized scutum. Leg I enlarged, with ventral cusps; Leg II with ventral cusps. Leg III and IV with sparse ventral tubercles on tibiae.

Palp ( Figs 2A–D , 3A–C ). Cymbium oval. Bulb oval. Sperm duct U-shaped, visible through median tegulum. Embolus coiled in horizontal plane, coils inclined towards retrolateral side of cymbium, partially covered by cymbium; embolar base sclerotized, forming median plate, originated in middle of tegulum. RTA long in retrolateral view, shorter than half of cymbium; apically strongly dorsally curved, apex not reaching dorsal cymbium outline.

Coloration and setation ( Fig. 1A–E ). Carapace and chelicera brown. Abdomen covered with fine setae; dorsal scutum gray; lateral and ventral surfaces cream, tinged with black.

Female. Unknown.

Distribution. Sarawak (known only from the type locality).

Figures

FIGURE 1. Utivarachna itiokai sp. nov., male, holotype (LMB_TY20180829_TR01). A habitus, dorsal view; B same, ventral view; C same, lateral view; D cephalic part and chelicerae, frontal view; E left leg I, prolateral view. Scale bars: 1 mm.

FIGURE 2. Utivarachna itiokai sp. nov., male, holotype (LMB_TY20180829_TR01). A left palp, prolateral view; B same, ventral view; C same, retrolateral view; D same, dorsal view. Scale bars: 0.50 mm. E—embolus, St—subtegulum.

FIGURE 3. Utivarachna itiokai sp. nov., male, holotype (LMB_TY20180829_TR01). A left palp, prolateral view; B same, ventral view; C same, retrolateral view. Scale bars: 0.25 mm. E—embolus, St—subtegulum