Dactylopisthes marginalis, Tanasevitch, 2018

Tanasevitch, Andrei V., 2018, A new species of Dactylopisthes Simon, 1884 from Thailand (Araneae, Linyphiidae), Revue suisse de Zoologie 125 (2), pp. 217-219 : 217-219

Dactylopisthes marginalis sp. nov.

Figs 1-7

Holotype: MHNG; male; THAILAND, Kanchanaburi Province, Sai Yok National Park, near park headquarters , 120 m a.s.l.; 14.XI.2000; leg. P. Schwendinger [sample TH-00/08 ] .

Diagnosis: The male palp conformation, namely, the structure of the embolic division in D. marginalis sp. nov., is most similar to that of the East Palaearctic - West Nearctic D. video ( Chamberlin & Ivie, 1947) . From it and from other congeners the new species clearly differs by its unmodified carapace, by its short tibial apophysis, as well as by the presence of a thin and long process on the distal suprategular apophysis (PP in Figs 2, 6 ). All known males of Dactylopisthes species ( D. separatus Zhao & Li, 2014 is so far only known from females) have an elevation on the carapace, and the palpal tibia is equipped with a long, usually sickle-shaped apophysis. In this sense D. marginalis sp. nov. seems to be an exceptional representative. Nevertheless, somatic characters, i.e. size, chaetotaxy, trichobothriotaxy, and especially structure of the embolic division, as well as the shape of the distal suprategular apophysis support the generic placement of the new species.

Etymology: The specific epithet is a Latin adjective referring to marginal systematic position of the new species within the genus.

Description: Male holotype. Total length 1.40. Carapace unmodified ( Fig. 1 ), 0.65 long, 0.53 wide, rounded, greyish pale yellow. Eyes normal, not enlarged. Chelicerae 0.28 long, mastidion absent. Legs pale yellow. Leg I 2.15 long (0.53+0.18+0.53+0.53+0.38), IV 2.24 long (0.58+0.20+0.55+0.53+0.38). Chaetotaxy 2.2.1.1, metatarsi unarmed. Length of spines 1.5-2 diameters of leg segment. Metatarsi IV without trichobothrium. TmI 0.42. Palp ( Figs 2-7 ): tibia short, with a wide, keel-shaped lateral outgrowth. Paracymbium wellsclerotized, L-shaped, its distal part wider than proximal one, hooked apically. Distal suprategular apophysis ( Fig. 6 ) highly developed, carrying three processes: proximal one (PP in Figs 2, 6 ) thin, long, directed backwards; distal one (DP in Figs 2, 6 ) L-shaped, very wide proximally, spike-shaped distally; lateral process (LP in Figs 2, 6 ) wide, short, highly sclerotized, with two short, unequal lobes, one distally rounded, the other truncate. Median membrane relatively wide and short. Column practically absent, embolic division situating very close to suprategulum. Radix flat, wide, with a notch in dorsal margin. Distal part of radix at base of embolus bent, carrying a wide, flat outgrowth, its edge in lateral view looking like a well-sclerotized, claw-shaped apophysis (RA in Figs 3, 7 ). Embolus very thin, short. Abdomen 0.75 long, 0.53 wide, dorsally almost white, with a longitudinal row of three pairs of indistinct, grey spots as shown in Fig. 1 .

Female. Unknown.

Taxonomic remarks: Dactylopisthes separatus has been described and perfectly illustrated by Zhao & Li (2014) on the basis of females from the extreme south of China. The authors attributed the species to the genus tentatively, and noted that the epigyne of this species resembles that of D. locketi ( Tanasevitch, 1983) , known from the Tian Shan Mts, Uzbekistan ( Tanasevitch, 1983). I also doubt that D. separatus belongs to Dactylopisthes , but even if not, the holotype of new species cannot be the conspecific male of the D. separatus types since these females are characterized by a specific coloration of the body. The male of D. marginalis sp. nov. has a completely different color pattern, see Fig. 1 and fig. 30B in Zhao & Li (2014). In most cases males and females of the same species have a similar color pattern of the body.

Distribution: Known only from the type locality in western central Thailand. ACKNOWLEDGEMENTS

Figures

Fig. 1. Photograph of Dactylopisthes marginalis sp. nov., male holotype, dorsal view.

Figs 2-7. Dactylopisthes marginalis sp. nov., male holotype. (2-3) Right palp, prolateral and retrolateral view, respectively.(4-5) Palpal tibia, dorsal and dorsolateral view, respectively. (6) Distal suprategular apophysis, anterolateral view. (7) Embolic division, ventrolateral view.