Zoma Saaristo, 1996

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 Zoma Saaristo, 1996

Type species.

Zoma zoma Saaristo, 1996, from Seychelles (not examined).

Composition.

Zoma zoma Saaristo, 1996, Z. dibaiyin Miller, Griswold & Yin, 2009, Z. fascia Zhao & Li, 2012, Z. taiwanica (Zhan, Zhu & Tso, 2006).

Remarks.

Females of the genus can be distinguished by the flat and bluntly triangular genital plate with a sclerotized median pit and a pair of smaller, generally less recognizable, lateral pits (Fig. 4J ; see also Saaristo 1996). Males of the type species Z. zoma have not yet been described. Therefore, the taxonomic characteristics of Zoma males are poorly defined. Males of three Zoma species, Z. dibaiyin , Z. fascia , and Z. taiwanica have relatively simpler palps with a filiform embolic apophysis emerging beneath from the conductor, while two or more apophyses in Theridiosoma (Fig. 3B, C vs. Fig. 5A, B ). Zoma species have wider and straight median apophysis, while curved and sharp tip in Theridiosoma (Fig. 3B-D vs. Fig. 5A-C ). Zoma species can be distinguished from congeners by the presence of a transverse whitish silver band on the dorsum abdomen ( Saaristo 1996; Miller et al. 2009).

Figures

Figure 3. Theridiosoma nigrivirgatum sp. nov., male holotype genitalia (NSMT-Ar 21717 A-D) and female paratype genitalia (NSMT-Ar 21718 E-G) A retrolateral view B ventral view C posterior-ventral view D prolateral view E ventral view F ventral view G dorsal view. Abbreviations: C conductor CD copulatory ducts E embolus EA embolic apophysis FD fertilization ducts MA median apophysis PC paracymbium S spermatheca ST subtegulum T tegulum. White and black arrows indicate a ridge that separate the two triangular surfaces and a sharply cornered terminal of the ridge, respectively. Scale bars: 0.1 mm.

Figure 4. Zoma dibaiyin Miller, Griswold & Yin, 2009, male habitus and genitalia (NSMT-Ar 21720 A-H) and female habitus and genitalia (NSMT-Ar 21721 I-K) A habitus, dorsal view B habitus, lateral view C palp, retrolateral view D palp, ventral view E palp, posterior-ventral view F palp, prolateral view G embolic division, prolateral view H embolic division, posterior-ventral view I habitus, dorsal view J epigyne, ventral view K vulva, dorsal view. Abbreviations: C conductor CD copulatory ducts E embolus EA embolic apophysis FD fertilization ducts MA median apophysis PC paracymbium PCP posterior conductor projection RCP retrolateral conductor projection S spermatheca ST subtegulum T tegulum. Arrows in E, F, H indicate a cornered margin of posterior membrane of conductor. Arrow in J indicates a sclerotized median pit. Scale bars: 1.0 mm (A, B, I); 0.1 mm (C-H, J, K).

Figure 5. Zoma dibaiyin Miller, Griswold & Yin, 2009, male genitalia (NSMT-Ar 21720) A ventral view B posterior-ventral view C prolateral view D conductor and embolic division, retrolateral view E conductor and embolic division, posterior-ventral view. Abbreviations: C conductor CD copulatory ducts E embolus EA embolic apophysis MA median apophysis PC paracymbium PCP posterior conductor projection RCP retrolateral conductor projection ST subtegulum T tegulum. Arrows in B-E indicate a cornered margin of posterior membrane of conductor. Scale bars: 0.1 mm.