Spinirta Jin & Zhang 2020, gen. nov.
Creators: name: Jin, Chi
name: Zhang, Feng
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Corinnidae
Spinirta

description: Spinirta gen. nov. (ḦẊĦoi)
Type species: Spinirta jinyunshanensis 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), 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, 12E), 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, 20G), 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), 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), not obvious when preserved in alcohol (Figs 4A, E; 8A, E); highest before fovea; thoracic region oval, cephalic region with parallel sides (Fig. 4A, E); 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). 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, 8D, 11D), not concave in female (Figs 4H, 8H, 11H); anterior surface clearly convex, posterior surface with distinct convex hump at its midpoint (Fig. 5B); promargin with three and retromargin with four to five teeth (Fig. 5A). 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). 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, 8A), absent in female (Figs 4E, 8E); posteriorly with several white chevrons forming longitudinal strip (Fig. 1); epigastric sclerite weakly sclerotized, post-epigastric sclerite present but small, ventral sclerite absent, inframamillary sclerite small in male and female (Fig. 4B, F). Posterior median spinnerets bearing three and posterior lateral spinnerets bearing two cylindrical gland spigots on apical truncation in female (Fig. 5D).
Palpal tibia (Fig. 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, 7D) elongate, with several thick setae on tip, without defined dorsal chemosensory patch. Tegulum (Figs 6B, 7B) 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). 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, 7B, 9E, 9B).
Epigynal region sclerotized. Copulatory openings anteriorly situated, large, separated (Figs 6G, 9G, 12G) or fused into large atrium (Figs 20E, 22E, 24E), with simple sclerotized margins. Copulatory ducts inflated anteriorly, membranous near openings; narrowing backwards, heavily sclerotized; parallel or slightly curved before joining spermathecae (Figs 6H, 9H). 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, 10F, 13F).
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).
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). 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), 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.
description: Published as part of Jin, Chi & Zhang, Feng, 2020, Spinirta gen. nov., a new dark sac spider genus from southern China (Araneae: Corinnidae), pp. 301-330 in Zootaxa 4838 (3) on pages 302-304, DOI: 10.11646/zootaxa.4838.3.1, http://zenodo.org/record/4403970