A newly-recorded species of the genus Ablemma Roewer, 1963 (Araneae, Tetrablemmidae) from China

Abstract Background Ablemma Roewer, 1963 is a species-rich genus of the family Tetrablemmidae O. Pickard-Cambridge, 1873, currently comprising 28 known species. This genus is mainly distributed in Southeast Asia. Currently, only one species, A.prominens Tong & Li, 2008 is known to occur in China. New information The species Ablemmashimojanai (Komatsu, 1968), presently only known from the Ryuku Islands in Japan, is reported from China for the first time on the basis of material collected in Guangdong Province. A morphological description and detailed images are provided.


Introduction
Tetrablemmidae O. Pickard-Cambridge is a small family of spiders known from tropical and subtropical regions. They are haplogyne, ecribellate spiders diagnosed from most other families by the presence of complex abdominal scuta (Jocqué and Dippenaar-Schoeman 2006). They are small (0.8-2.0 mm), cryptic spiders predominantly living in leaf litter, soil and caves (Burger et al. 2010).
Tetrablemma shimojanai Komatsu, 1968 was described, based on a single male collected in Inamiji Cave in Okinawa, Japan (Komatsu 1968) and was later transferred to the genus Ablemma Roewer, 1963by Shear (1978. This species is widely distributed in the Ryukyu Chain and often can be found in limestone caves (Shimojana 1977). A recent investigation revealed that A. shimojanai also occurs in the leaf litter of deciduous forests (Suzuki et al. 2018). However, this species is still poorly known. Details of the male palp are currently known, based on drawings only (Komatsu 1968, Shear 1978 and no images exist of the internal female genitalia.
In this paper, Ablemma shimojanai is recorded from China for the first time and a detailed description and illustrations of this species are provided.

Materials and methods
The specimens used in this study were collected by sifting leaf litter and later examined using a Leica M205C stereomicroscope. Photos were made with a Canon EOS 750D zoom digital camera (18 megapixels) mounted on an Olympus BX51 compound microscope. Scanning electron microscope (SEM) images were taken under high vacuum with a Hitachi TM3030 after critical-point drying and gold-palladium coating. All measurements were taken using an Olympus BX51 compound microscope and are given in millimetres.
Female. Habitus as in Fig. 2A

Diagnosis
This species is similar to Ablemma berryi Shear, 1978 in the large conical projection of male carapace (cf. Fig. 1C and F and Shear 1978: fig. 90), but can be distinguished by the acute tip of the embolus (Fig. 3A-I; vs. very long, laminar embolus, see Shear 1978: figs 93 and 94) and the large preanal plate, which is nearly four times the length of the postgenital plate ( Fig. 1H and Fig. 2H; vs. two times the length of the postgenital plate, see Shear 1978: fig. 95).