Three new species of the genus Falcileptoneta Komatsu, 1970 (Araneae, Leptonetidae) from Korea

Abstract Three new species of the genus Falcileptoneta Komatsu, 1970 belonging to the spider family Leptonetidae Simon 1890 are described from Korea. All species were collected from wet leaf litter layers.


Introduction
The family Leptonetidae Simon, 1890 currently contains 21 genera and 349 species worldwide (World Spider Catalog 2019). Most species are tiny (1-3 mm) and have six eyes with the posterior median eyes located behind the posterior lateral eyes; some species have only four or two eyes or are eyeless. Most species live in irregular sheet webs in leaf litter, caves, or mines. In Korea, there are 42 species in four genera: Leptoneta Simon, 1872, Falcileptoneta Komatsu, 1970, Masirana Kishida, 1942and Longileptoneta Seo, 2015. Komatsu (1970 erected Falcileptoneta with F. striatus (Oi 1952) as the type species (transferred from Leptoneta). Prior to this study, 47 Falcileptoneta species have been described from Korea and Honshu, Shikoku in Japan (Irie and Ono 2007). In this study, three new species of Falcileptoneta are illustrated and described.

Materials and methods
All specimens were collected by hand from mountainous districts in northern South Korea. Type specimens are deposited in the National Institute of Biological Resources (NIBR) in Incheon, Korea and the Institute of Zoology, Chinese Academy of Sciences (IZCAS) in Beijing, China. All spiders were preserved in 95% ethanol and examined under a LEICA M205C stereomicroscope. Images were captured with an Olympus C7070 wide zoom digital camera (7.1 megapixels) mounted on an Olympus SZX12 dissecting microscope, and Helicon Focus image stacking software was used to compile the images. All images were edited with Adobe Photoshop CS8.1. Methods follow those of Wang and Li (2011) and Ledford et al. (2011); terminology follows Wang et al (2017

Family Leptonetidae Simon, 1890
Genus Falcileptoneta Komatsu, 1970 Type species. Leptoneta striatus Oi, 1952 Diagnosis. The genus Falcileptoneta is similar to Leptoneta and Longileptoneta by having fewer sclerites on the bulb but can be distinguished from these two genera by the combination of the following characters: tarsus of male palp with shallow, transverse depression and without spines; tibia with apophyses on the retrolateral apical end; bulb with sickle-like or membranous embolus; complex laminae of the bulb. Leptoneta can be distinguished by the tarsus with a branch bearing an apical spine. Longileptoneta can be identified by the strong femoral spines, the prolateral curvature bearing a prolateral distal spur on the tarsus, a finger-like median sclerite, and a leaf-like embolus.
Comments. According to the original description, the genus Falcileptoneta is similar to Leptoneta but can be distinguished by the falcula on the tibia of the male palp. Femur normal. Tibia with three trichobothria, and the apical end with spine-like apophyses. Tarsus with several bristles but no spines and a weak transverse depression. We have added descriptions of the following characters: the shape of the embolus and the laminae of the bulb.
Distribution. Korea, Japan. Etymology. The specific name is an adjective referring to the type locality. Differential diagnosis. This new species is similar to F. geumsanensis Seo, 2016 and F. boeunensis Seo, 2015 but can be separated by the shape of the palpal tibial apophyses found retrolaterally, with one apophysis coniform and the other bifurcate, bearing three spines distally ( Figure 1D) (vs. a spur-like tibial apophysis located ventrally, a leaf-like medial apophysis, a dorsal beak-like apophysis in F. geumsanensis; three tibial spines with the outer spine spur-like, the medial one spine-like, and the inner spine conical in F. boeunensis.).
Female (one of the paratypes). Similar to male in color and general features but larger and with longer legs. Total length 1.39 as in Figure 2A Figure 2C: atrium rectangular, anterior margin of atrium with short hairs, and spermathecae oval.
Habitat. Litter layers in mixed forest. Distribution. Korea (Gyeonggi-do).    Figure 3D) (vs. tibial apophysis with two whipshaped hairs bearing minute setae and the main apophysis spiniform in F. amakusaensis; tibial apophysis with two spur-like retrolateral apophyses in F. geumdaensis; tibial apophysis with two retrolateral spines with the dorsal one thick and spur-like in F. sunchangensis).
Habitat. Litter layers in mixed forest. Distribution. Korea (Gangwon-do).     be separated by one hook-like retrolateral apophysis on the palpal tibia, leaf-shaped median apophysis, and sickle-shaped embolus ( Figure 5C) (vs. short tubercle without spines or bristles on tibia, hook-shaped median apophysis and sickle-shaped embolus in F. yebongsanensis; spine-shaped embolus and median apophysis in L. kwangreungensis).
Female (one of the paratypes). Similar to male in color and general features. Total length 1.51 ( Figure 6A Figure 6C: atrium wrinkled, trapezoidal, genital duct coiled apically, and spermathecae round. Habitat. Litter layers in mixed forest. Distribution. Korea (Seoul).