Spinirta, Jin & Zhang, 2020

Jin, Chi & Zhang, Feng, 2020, Spinirta gen. nov., a new dark sac spider genus from southern China (Araneae: Corinnidae), Zootaxa 4838 (3), pp. 301-330 : 302-304

publication ID	https://doi.org/ 10.11646/zootaxa.4838.3.1
publication LSID	lsid:zoobank.org:pub:112D4DC3-723A-4216-A608-3D03B392E973
DOI	https://doi.org/10.5281/zenodo.4404457
persistent identifier	https://treatment.plazi.org/id/389E47D6-79DF-4276-9E32-2332831D6929
taxon LSID	lsid:zoobank.org:act:389E47D6-79DF-4276-9E32-2332831D6929
treatment provided by	Plazi
scientific name	Spinirta
status	gen. nov.

Treatment

Spinirta View in CoL gen. nov. (ḦẊĦoi)

Type species: Spinirta jinyunshanensis View in CoL sp. nov.

Etymology. The generic name is a combination of “spine” and “rta”, meaning “spinous RTA”, referring to the short thick spines on the ventral surface of the retrolateral tibial apophysis of the male palp. The gender is feminine.

Diagnosis. Unlike most genera in Corinnidae , Spinirta gen. nov. resembles Allomedmassa , Medmassa and Paramedmassa in having a well-developed RTA, unspiraled sperm duct, tegulum lacking a conductor, tegular apophysis and median apophysis, and a non-ant-mimicking body.

The new genus can be easily distinguished from its close relatives by: 1) RTA usually ear-shaped or spoonshaped, with dense or sparse thick short spines on its ventral surface ( Fig. 3 View FIGURE 3 ), whereas it is sharp and spiniform in Allomedmassa ( Jin et al. 2019: figs 2E–G), often forked in Medmassa ( Deeleman-Reinhold 2001: figs 534–535), and cylindrical and bifurcated in Paramedmassa ( Jin et al. 2019: figs 10F–H); 2) embolus extremely stout, bifurcated, and with file-like grooves on the surface of the lateral branch ( Figs 6E View FIGURE 6 , 12E View FIGURE 12 ), whereas it is long, S-shaped and with a smooth surface in Allomedmassa ( Jin et al. 2019: figs 2F–G), slender and spiniform in Medmassa (Deeleman-Reinhold 2001: fig. 545), and curved and sharp in Paramedmassa ( Jin et al. 2019: fig. 10F); 3) COs anteriorly situated, large, separated or fused into a large atrium, with simple sclerotized margins ( Figs 6G View FIGURE 6 , 20G View FIGURE 20 ), whereas they are medially situated, large and separated in Allomedmassa ( Dankittipakul & Singtripop 2014: figs 12, 15), anteriorly situated, separated and small in Medmassa ( Haddad & Bosselaers 2010: figs 8–10), and anteriorly situated, large and with complex sclerotized margins in Paramedmassa ( Jin et al. 2019: fig. 11E); 4) spermathecae spherical ( Figs 6H, 6F View FIGURE 6 ), whereas they are reniform in Allomedmassa ( Dankittipakul & Singtripop 2014: fig. 12), oval in Medmassa ( Haddad & Bosselaers 2010: figs 8–11), and clavate in Paramedmassa ( Jin et al. 2019: fig. 11F).

Description. Medium to large-sized (8.30–15.44 mm), dark, non-ant-mimicking spiders. Carapace dark brown to black, convex, with rough surface, middle with broad longitudinal stripe of white feathery hairs, from ocular area to fovea, which is obvious when alive ( Fig. 1 View FIGURE 1 ), not obvious when preserved in alcohol ( Figs 4A, E View FIGURE 4 ; 8A, E View FIGURE 8 ); highest before fovea; thoracic region oval, cephalic region with parallel sides ( Fig. 4A, E View FIGURE 4 ); widest at coxae II, gradually narrowing backwards, straight or slightly concave at posterior margin before pedicel; radial and cervical grooves indistinct; fovea longitudinal, short. Ocular area wide, about 0.7 times CRW. AER straight in frontal view, PER straight in dorsal view; AME largest, round; ALE smallest, oval ( Fig. 4D, H View FIGURE 4 ). Clypeus height narrower than diameter of AME. Chilum present, single, triangular, sclerotized and brown. Chelicerae same color as carapace; slightly concave at distal end dorsally in male ( Figs 4D View FIGURE 4 , 8D View FIGURE 8 , 11D View FIGURE 11 ), not concave in female ( Figs 4H View FIGURE 4 , 8H View FIGURE 8 , 11H View FIGURE 11 ); anterior surface clearly convex, posterior surface with distinct convex hump at its midpoint ( Fig. 5B View FIGURE 5 ); promargin with three and retromargin with four to five teeth ( Fig. 5A View FIGURE 5 ). Endites and labium lighter in color than carapace, longer than wide. Sternum lighter than endites and labium, shield-shaped, longer than wide, precoxal triangles and intercoxal sclerites present ( Fig. 4B View FIGURE 4 ). All femora of legs black, other segments reddish-brown to dark brown; anterior tibiae with four pairs of ventral spines; anterior metatarsi with two pairs of ventral spines; metatarsi III–IV ventrally with distal preening brush. Leg formula 4123. Leg spination highly uniform among all species: femora I pl 1 do 2, II do 2, III–IV pl 1 rl 1 do 3; patellae I–IV do 2; tibiae I–II plv 4 rlv 4, III–IV pl 2 rl 2 plv 2 rlv 2; metatarsi I–II plv 2 rlv 2, III–IV plv 2 rlv 2 vt 3; tarsi I–IV spineless. Palpal spination: female: femur do 1, patella do 2 pl 1, tibia do 1 pl 2, tarsus pl 2; male: femur do 1, patella do 2 pl 1, tibia pl 2. Abdomen oval, dark brown to black, with narrow anterior dorsal scutum in male ( Figs 4A View FIGURE 4 , 8A View FIGURE 8 ), absent in female ( Figs 4E View FIGURE 4 , 8E View FIGURE 8 ); posteriorly with several white chevrons forming longitudinal strip ( Fig. 1 View FIGURE 1 ); epigastric sclerite weakly sclerotized, post-epigastric sclerite present but small, ventral sclerite absent, inframamillary sclerite small in male and female ( Fig. 4B, F View FIGURE 4 ). Posterior median spinnerets bearing three and posterior lateral spinnerets bearing two cylindrical gland spigots on apical truncation in female ( Fig. 5D View FIGURE 5 ).

Palpal tibia ( Fig. 3 View FIGURE 3 ) short, nearly equal in length and width, ventral surface usually raised as hump or apophysis; prolateral tibial apophysis triangular; retrolateral tibial apophysis usually ear-shaped or spoon-shaped, with dense or sparse thick short spines on ventral surface, located at distal end of tibia, pointed anteriorly. Cymbium ( Figs 6D View FIGURE 6 , 7D View FIGURE 7 ) elongate, with several thick setae on tip, without defined dorsal chemosensory patch. Tegulum ( Figs 6B View FIGURE 6 , 7B View FIGURE 7 ) elongate oval, with parallel sides; base round, retrolateral apex usually hump-like; without other structures except embolus; sperm duct thick, U-shaped. Subtegulum surface wrinkled ( Fig. 7A, B View FIGURE 7 ). Embolus extremely stout, directed dorsally, basal width often more than 1/2 of tegulum width; embolus with file-like grooves on surface, usually bifurcated, with embolar apophysis prolaterally ( Figs 6E View FIGURE 6 , 7B View FIGURE 7 , 9E, 9B View FIGURE 9 ).

Epigynal region sclerotized. Copulatory openings anteriorly situated, large, separated ( Figs 6G View FIGURE 6 , 9G View FIGURE 9 , 12G View FIGURE 12 ) or fused into large atrium ( Figs 20E View FIGURE 20 , 22E View FIGURE 22 , 24E View FIGURE 24 ), with simple sclerotized margins. Copulatory ducts inflated anteriorly, membranous near openings; narrowing backwards, heavily sclerotized; parallel or slightly curved before joining spermathecae ( Figs 6H View FIGURE 6 , 9H View FIGURE 9 ). Accessory glands small, spherical or digitiform, located ectally of copulatory ducts. Spermathecae small, spherical, situated posteriorly, mostly separated from each other. Fertilization ducts short, connected to posterior margin of epigyne with membrane ( Figs 7F View FIGURE 7 , 10F View FIGURE 10 , 13F View FIGURE 13 ).

Composition. Ten species: Spinirta jinyunshanensis sp. nov., S. forcipata sp. nov., S. sparsula sp. nov., S. aurita sp. nov., S. aviforma sp. nov., S. quadrata sp. nov., S. leigongshanensis sp. nov., S. qizimeiensis sp. nov., S. rugosa sp. nov. and S. qiaoliaoensis ( Lu & Chen, 2019) comb. nov..

Distribution. Southern China ( Fig. 26 View FIGURE 26 ).

Biology. Specimens were collected using a variety of sampling methods and occupy most strata of evergreen broadleaf forest habitats (tree canopies, shrubs and leaf litter) ( Fig. 2D View FIGURE 2 ). Most of them were collected by beating branches of short trees, found in the natural curly dead leaves of shrubs during the day ( Fig. 2 View FIGURE 2 ), collected in the litter layer, or occasionally collected by pitfall traps. It is speculated that they are predominantly arboreal, and they will also wander on the ground, using natural curly dead leaves as retreats without building silk retreats.