Sennin, Suzuki & Hiramatsu & Tatsuta, 2022

Suzuki, Yuya, Hiramatsu, Takehisa & Tatsuta, Haruki, 2022, Two new species and a new genus of ray spiders (Araneae, Theridiosomatidae) from the Ryukyu Islands, southwest Japan, with notes on their natural history, ZooKeys 1109, pp. 67-101 : 67

Genus Sennin gen. nov.

Type species.

Sennin tanikawai sp. nov.

Etymology.

The generic name Sennin is noun in apposition, masculine, and derived from the Japanese word meaning mountain hermits, a person who acquires a spiritual power after living a secluded life deep in the mountains. Iriomote Island, where the new species inhabits, is famous for a man called Sennin , who was self-sufficient, lived in the coastal caves, and single-handedly built a wooden hut.

Diagnosis.

This genus can be distinguished from other theridiosomatid genera by the following characteristics: a large, oblong cymbial outgrowth (cymbial apophysis) protruding from the basal and dorsal part of cymbium of male palp (Figs 7A-C , 9 A-C ); an embolic division with three elongated bristle-like embolic apophyses with the longest one coiled (Figs 7F-J , 9F-J ); the anterior margin of the epigynal plate with a pair of sclerotized, triangular extensions protruding anteriorly from the anterolateral side (Figs 8A, D ; 10A, D ; arrowed; Zhu et al. 2001: fig. 4; Chen 2010: figs 19, 20); the vulva with long copulatory ducts coiling at the lateral side of the spermatheca (Figs 8C, D , 10C, D ).

Composition.

Sennin tanikawai sp. nov., S. coddingtoni (Zhu, Zhang & Chen, 2001), comb. nov.

Remarks.

This genus is related to Baalzebub Coddington, 1986, based on the shape of the median apophysis on the male palp, the embolic apophyses that are not exposed from the conductor, and the general morphology of the epigyne. The elongated and oblong dorsal cymbial apophysis, one of the most conspicuous characters of Sennin gen. nov. (Figs 7A-C , 9A-C ), differentiates the new genus from Baalzebub . Although some species of Baalzebub have a small protrusion on the retrolateral-dorsal side of basal part of cymbium (e.g., paracymbium in B. acutum ; Prete et al. 2016: figs 2D, 3C; named ‘Höcker’ (= lump) in B. brauni ; Wunderlich 1976: figs 17, 18), it is not as prominent as that of Sennin gen. nov. The embolic apophyses of Baalzebub are short, blunt, and spatulate, but those of Sennin are longer, bristle-like, and strongly curved or coiled (Figs 7F-J , 9F-J ). As for the female genitalia of species of Baalzebub , the epigynal plate is upside-down triangular with sclerotized central epigynal pit, the spermathecae elliptical, and longer laterally with connate tips, and the course of copulatory ducts is simple ( Coddington 1986a). Sennin gen. nov. has similar spermathecae, but the course of the copulatory duct is more complex, with a coiled trajectory at the basal side of the spermathecae (Figs 8C, D , 10C, D ).

Sennin coddingtoni comb. nov. was formerly placed in Karstia Chen, 2010, but it shares conspicuous characteristics with S. tanikawai sp. nov. and can clearly be differentiated from K. upperyangtzica Chen, 2010, the type species of the genus. Therefore, we transferred it from Karstia to Sennin gen. nov. Karstia upperyangtzica and K. cordata Dou & Li (2012) females have an upside-down triangular epigynal plate with a sclerotized epigynal pit, and a simple course of copulatory ducts; males have cymbial apophysis as a very small protrusion, and embolic division with short, spatulate embolic apophyses ( Chen 2010; Dou and Lin 2012; Zhang and Wang 2017). Based on these morphological characteristics, it is difficult to differentiate K. upperyangtzica and K. cordata from Baalzebub ; therefore, taxonomic revision of Karstia is needed. In this study, we defer revision of Karstia , which may require direct examination of the type specimens and further molecular analysis.

As mentioned above, taxonomic relationship between Sennin gen. nov. and its potentially closest-related genera ( Baalzebub and probably Karstia ) is not yet well defined. This also indicated that the establishment of Sennin gen. nov. could render these related genera polyphyletic. To revise taxonomic status of these taxa in terms of monophyly, further integrative phylogenetic approach covering large number of species and genera is required.

According to the morphology and a potential close-relatedness to Baalzebub , Sennin gen. nov. is here suggested to be assigned to the subfamily Theridiosomatinae .

Figures

Figure 7. Sennin tanikawai sp. nov., male holotype genitalia (NSMT-Ar 21722) A-D male palp F-J embolic division A retrolateral view B prolateral view C dorsal view D ventral view E median apophysis, ventral view F posterior-ventral view G ventral view H anterior-dorsal view I posterior-dorsal view J prolateral view. Abbreviations: C conductor CA cymbial apophysis CL cymbial lamella E embolus EA embolic apophysis ED embolic division EM embolus MA median apophysis PC paracymbium ST subtegulum T tegulum. Arrow in E indicates the tip of less-sclerotized region of median apophysis. Scale bars: 0.1 mm.

Figure 8. Sennin tanikawai sp. nov., female paratype genitalia (NSMT-Ar 21723) A epigyne, ventral view B epigyne, lateral view C vulva, dorsal view D vulva, anterior view. Abbreviations: CB copulatory bursae CD copulatory ducts ES epigynal scape FD fertilization ducts S spermatheca. Arrows in A, D indicate a pair of sclerotized extensions on the anterior margin of epigynal plate. Arrow in C indicates a pair of copulatory ducts juxtaposed. Scale bars: 0. 1 mm.

Figure 9. Sennin tanikawai sp. nov., male holotype genitalia (NSMT-Ar 21722) A-D male palp F-J embolic division A retrolateral view B prolateral view C dorsal view D ventral view E median apophysis, ventral view F posterior-ventral view G ventral view H anterior-dorsal view I posterior-dorsal view J prolateral view. Abbreviations: C conductor CA cymbial apophysis CL cymbial lamella E embolus EA embolic apophysis ED embolic division EM embolus MA median apophysis PC paracymbium ST subtegulum T tegulum. Arrow in E indicates the tip of less-sclerotized region of median apophysis. Scale bars: 0.1 mm.

Figure 10. Sennin tanikawai sp. nov., female paratype (NSMT-Ar 21723) A epigyne, ventral view B epigyne, lateral view C vulva, dorsal view D vulva, anterior view E course of copulatory duct. Abbreviations: CB copulatory bursae CD copulatory ducts ES epigynal scape ESL epigynal scape length FD fertilization ducts S spermatheca VW vulva width. Arrows in A, D indicate a pair of sclerotized extensions on the anterior margin of epigynal plate. Arrow in C indicates the pair of copulatory ducts juxtaposed. Scale bars: 0.1 mm.