Monday, December 28, 2020

[Arachnida • 2020] Japanese Spiders of the Genus Theridiosoma (Araneae: Theridiosomatidae) with the Description of Four New Species


Habitus of Theridiosoma species when alive.  
A-D, Theridiosoma epeiroides; E-H, T. dissimulatum sp. nov.
I-L, T. paludicolum; M-O, T. fulvum. P, T. alboannulatum sp. nov. 

in Suzuki, Serita & Hiramatsu, 2020.
Japanese spiders of the genus Theridiosoma (Araneae: Theridiosomatidae) were revised with redescription of T. epeiroides Bösenberg & Strand 1906 and description of four new species, namely: T. dissimulatum sp. nov., T. paludicolum sp. nov., T. fulvum sp. nov., and T. alboannulatum sp. nov. The internal morphology of the female genitalia of T. epeiroides is illustrated in this study for the first time. Males of the new species can be distinguished from their congeners by the morphology of the embolic apophyses or the posterior edge of the embolic division on the male palp. Females of the former three species can be differentiated from their related species by the shape of the contour formed by interior edges of a pair of sclerotized processes on the posterior edge of the genital plate. The latter species can be distinguished from the allied species by the angular lateral corners of the genital plate and overall shape of the genitalia (longer than wide).

Keywords: Conductor projection, embolic apophysis, epigyne, morphology, new species, process, taxonomy

Habitus of Theridiosoma species when alive. 
 A, Theridiosoma epeiroides, male (Ibaraki Pref.); B–C, same, female (Ibaraki Pref.); D, same, female (Tokyo); E, T. dissimulatum sp. nov., female (Amami-ohshima Is.); F same, female (Okinawa-jima Is.); G–H, same, female (Iriomote-jima Is.); I, T. paludicolum, male (Chiba Pref.); J, same, male lacking white markings on abdomen (Kochi Pref.); K, same, female (Chiba Pref.); L, same, female with light brown colored body (Kochi Pref.); M, T. fulvum, male and female (Ibaraki Pref.); N, same, female (Saitama Pref.), O, same, female with light colored markings on abdomen (Ibaraki Pref.). P, T. alboannulatum sp. nov., female (Iriomote-jima Is.). Note that all the photographs are not identical to type materials except that of T. alboannulatum (paratype female).

Yuya Suzuki, Ryohei Serita and Takehisa Hiramatsu. 2020. Japanese Spiders of the Genus Theridiosoma (Araneae: Theridiosomatidae) with the Description of Four New Species. Acta Arachnologica. 69(2): 133–150. DOI: 10.2476/asjaa.69.133