Myrmarachne leptosoma Yamasaki, 2018

Yamasaki, Takeshi, Hashimoto, Yoshiaki, Endo, Tomoji, Hyodo, Fujio, Itioka, Takao & Meleng, Paulus, 2018, New species of the ant-mimicking genus Myrmarachne MacLeay, 1839 (Araneae: Salticidae) from Sarawak, Borneo, Zootaxa 4521 (3), pp. 335-356 : 346-348

Myrmarachne leptosoma Yamasaki sp. nov.

( Figs 34–42 )

Type material. Holotype: male ( FRCS; LMy20090225_E11), Crane-site , Lambir Hills National Park, Sarawak, Borneo, 25.II.2009, T. Endo leg. Paratype: 1 male ( MNHAH; LMy20140330_ TY31 ), Tower 1, same locality as in the holotype, 30.III.2014, T. Yamasaki leg.

Etymology. The specific name, a noun in apposition, is derived from Greek adjective “leptos” and noun “soma”, meaning a slender body, referring to the spider general shape.

Diagnosis. Slender species with very long pedicel; carapace, pedicel, and abdomen approximately equal in length. Myrmarachne leptosoma sp. nov. is distinguishable from other Asian Myrmarachne species, except M. lagarosoma sp. nov. by the very long pedicel; male distinguishable from M. lagarosoma by swollen structure on anterior dorsal plate of pedicel, and tooth-like protuberance on anterior corner of carapace.

Male ( Figs 34–39 ). Carapace slender; dorsal and lateral surfaces strongly constricted between cephalic and thoracic parts; tooth-like protuberance developing from anterior corner of cephalic part below ALE. Cheliceral paturon slightly shorter than carapace, with five prolateral and seven small retrolateral teeth on fang furrow. Fang without tooth-like apophysis. Pedicel very long; anterior dorsal plate (lorum) much longer than posterior one; anterior lorum thick in posterior part, bearing protuberance, and with developed rim on posterior end. Abdomen slender-oval without distinct constriction; dorsum mostly covered with elongate-oval median scutum.

Male palp ( Figs 40–42 ). Cymbium oval, with two macrosetae apically; cymbium wider than embolus coils. Tegulum round, with spermophore along margin. RTA very slender distally, but proximally broad, without strong curve and apical hook.

Leg macrosetae. Tibia I pv 3, rv 3; metatarsus I pv 1–2, rv 2; tibia II pv 0, rv 1–2; metatarsus II pv 0–2, rv 0–2; legs III and IV without macrosetae.

Coloration and setation ( Figs 34–38 ). Carapace dark brown, covered with long setae; lateral surface of constricted area covered with white setae. Cheliceral paturon and fang dark brown; outer surface of chelicera covered with long setae. Endite, labium and sternum brown, tinged with black. Pedicel dark brown, covered with long setae. Abdomen covered with long fine setae; dorsum dark brown; venter gray with brown epigastric surface and median rectangle area. Live male appearance shown in Figure 34 .

Measurements (2 males). Total length 6.0–6.6. Carapace length 2.30–2.47, width 1.32–1.37. Length of cheliceral paturon of male 1.75. Width of eye row I 1.02–1.08: II 1.00–1.03; III 1.0 8–1.17. ALE–PLE 0.85–0.92. ALE–PME 0.37–0.40. Eye size: AME 0.33–0.34; ALE 0.15–0.18; PME 0.06; PLE 0.18–0.20. Pedicel length 1.98– 2.00. Abdomen length 2.30–2.30.

Female. Unknown.

Distribution. Known only from Borneo.

Remarks. See Remarks in M. lagarosoma sp. nov. Although M. leptosoma shares the very long pedicel with M. lagarosoma , their relationship is still unclear.

Figures

FIGURES 34–42. Myrmarachne leptosoma sp. nov., male. 34 paratype male (LMy20140330_TY31), in living condition, dorsal view; 35–42 holotype male (LMy20090225_E11). 35 dorsal view; 36 ventral view; 37 lateral view; 38 left fang, cheliceral paturons and cephalic part, dorsal view; 39 left cheliceral paturon and fang, ventral view; 40 right palp, ventral view; 41 retrolateral view; 42 right palpal tibia, dorsal view. Scales: 35–38: 1 mm; 39: 0.5 mm; 40–42: 0.25 mm.