Dichodactylus shinshuensis, Okumura, 2017

Okumura, Ken-ichi, 2017, Dichodactylus gen. nov. (Araneae: Agelenidae: Coelotinae) from Japan, Species Diversity 22 (1), pp. 29-36 : 31

Dichodactylus shinshuensis sp. nov.

( Figs 2 A–D, 5A, D, 6)

Coelotes sp.: Chikuni 1989: 103, fig. 25.

Type material. All collected by Yoh Ihara. Holotype: male, Ōjimasan, 840 m alt., Takamori Town, Shimo-ina County, Nagano Pref. (35°57′2″N, 137°84′1″E), 21. X. 2010 (NSMT-Ar 13339). Paratypes: 1 male and 1 female, Tochibaradani , Ochiai , Osaka Town , Gero City , Gifu Pref. (35°95′7″N, 137°34′1″E), 14, X. 2009 (NSMT-Ar 13340, 13341).

Diagnosis. Dichodactylus shinshuensis sp. nov. can be distinguished from all the other Dichodactylus species by having the tip of the male palpal conductor twisted proximally at a right angle ( Fig. 2A ), the presence of a pair of lamellae laterally on the epigynum ( Figs 2C , 5D ) and the prominent copulatory ducts visible in ventral view of cleared vulva ( Fig. 2D ).

Description of male (holotype). Total length 5.6, carapace 2.9 long, 2.0 wide; abdomen 2.7 long, 1.6 wide; sternum 1.6 long, 1.3 wide. Eye sizes; AME 0.07, ALE 0.15, PME 0.12, PLE 0.14. Distances between eyes; AME-AME 0.07, AME-ALE 0.04, PME-PME 0.09, PME-PLE 0.12, AME-PME 0.10, ALE-PLE 0.04. MOA; anterior width 0.21, posterior width 0.33, length 0.29. Leg measurements: I: 7.9 (2.1, 2.7, 1.9, 1.2); II: 7.1 (2.1, 2.3, 1.7, 1.0); III: 6.6 (1.7, 2.1, 1.9, 0.9); IV: 9.4 (2.5, 3.0, 2.7, 1.2).

Palp ( Figs 2A, B , 5A ): two patellar apophyses present, situated at a right angle from each other in retrolateral view, LTA reduced, RTA large and broad; cymbial furrow short and indistinct about one-sixth of cymbial length; embolus flagelliform and short, conductor spatulate and tip twisted proximally at a right angle; median apophysis small, crescent-shaped; tegulum with swollen portion visible in retrolateral view.

Description of female (paratype). Total length 5.0, carapace 2.7 long, 1.5 wide; abdomen 2.3 long, 1.4 wide; sternum 3.2 long, 2.4 wide. Eye sizes; AME 0.06, ALE 0.14, PME 0.12, PLE 0.10. Distances between eyes; AME-AME 0.04, AME-ALE 0.03, PME-PME 0.07, PME-PLE 0.10, AME-PME 0.09, ALE-PLE 0.03. MOA; anterior width 0.16, posterior width 0.31, length 0.27. Leg measurements: I: 6.3 (1.9, 2.1, 1.4, 0.9); II: 5.6 (1.7, 1.8, 1.3, 0-8); III: 5.3 (1.5, 1.8, 1.3, 0.7); IV: 7.2 (2.0, 2.4, 1.9, 0.9).

Epigynum and internal genitalia ( Figs 2C, D , 5D ): epigynum hourglass-shaped, atrium large, almost rectangular and somewhat longer than wide, lamellae situated laterally to atrium, epigynal teeth absent, spermathecae elongated anteroposteriorly and well-separated on lateral edges of vulva, copulatory ducts prominent, large, irregularly convoluted and very visible in dorsal view of cleared vulva.

Distribution. Chubu District, central Japan (Nagano Pref., Gifu Pref.) ( Fig. 6 ).

Etymology. Specific name is an adjective derived from the provincial name of Nagano Prefecture including the type locality.

Figures

Fig. 2. Dichodactylus shinshuensis sp. nov., male (A, B: holotype, NSMT-Ar 13339), female (C, D: paratype, NSMT-Ar 13341). A, ventral view of male palp; B, retrolateral view of male palp; C, ventral view of epigynum; D, dorsal view of internal female genitalia. Abbreviations: CD, copulatory duct; CO, conductor; CY, cymbial furrow; EM, embolus; LAM, lamellas; MA, median apophysis; PA, patellar apophyses; RTA, retrolateral tibial apophysis; SP, spermatheca. Scale bars: 0.5mm.

Fig. 5. Comparison of genitalic characters of three species of Dichodactylus gen. nov. from Japan: A, D, D. shinshuensis sp. nov., male (A: NSMT-Ar 13339), and female (D: NSMT-Ar 13341); B, E, D. tarumii (Arita, 1976), male (B: NSMT-Ar 14732), and female (E: NSMT-Ar 14733); C, F, D. satoi (Nishikawa, 2003), male (C: NSMT-Ar 14735), and female (F: NSMT-Ar 14734). A–C, retrolateral views of male palp; D–F, ventral views of epigynum. Abbreviations: CO, conductor; ET, epigynal teeth; LAM, lamellas; PA, patellar apophyses; SW, swollen portion of tegulum. Black circle on tibia shows the vestigial LTA.

Fig. 6. Distribution of three species of the genus Dichodactylus gen. nov. from Japan. Closed circles denote D. shinshuensis sp. nov.; closed inverted triangles, D. tarumii (Arita, 1976); crosses, D. satoi (Nishikawa, 2003).