Note on the genus Serendib Deeleman-Reinhold, 2001, with the description of a new species (Araneae, Corinnidae, Castianeirinae)

Abstract Background Prior to this study, the genus Serendib Deeleman-Reinhold, 2001 has been discovered in Indonesia, Thailand and Laos and comprises three species: S.muadai Jäger, Nophaseud & Praxaysombath, 2012, S.suthepica Deeleman-Reinhold, 2001 and S.volans Deeleman-Reinhold, 2001. New information The genus Serendib Deeleman-Reinhold, 2001 is reviewed. A new species, S.hispida sp. n. (male and female), representing the first record of genus Serendib from Malaysia, is described. Descriptions and illustrations of the females of S.volans (Malaysia) and S.suthepica (China) are also provided. The latter represents the first record of the genus in China.

While examining the corinnids specimens collected from the Oriental Region during the past decade, we found one species that is consistent with the generic characteristics of Serendib, namely S. hispida sp.n., representing the first record of Serendib from Malaysia.The species, Serendib volans and S. suthepica are redescribed, with the latter recorded from China for the first time, representing the northernmost record for Serendib.Descriptions and illustrations are provided for the females of two known species and both sexes of one new species.

Materials and methods
All measurements are given in millimetres (mm).Leg measurements are shown as total length (femur, patella, tibia, metatarsus, tarsus).Epigynes were removed and cleared in a pancreatin solution (Álvarez-Padilla and Hormiga 2007).All specimens are preserved in 95% alcohol and were examined, illustrated and measured with a Leica M205A stereomicroscope.Somatic photographs were captured using a Leica M205A stereomicroscope, equipped with a DFC550 CCD camera and morphology photographs were taken using an Olympus BX51 microscope equipped with a Kuy Nice CCD with a Canon 60 mm micro-lens and were imported into Helicon Focus 7 for stacking.Drawings were used with Inkscape version 1.0.2.0.Final figures were retouched with Adobe Photoshop CC © 2022.The distribution map was made using ArcGIS Desktop version 10.6.The specimens used in this study are deposited in the Museum of Hebei University, Baoding, China (MHBU).
The abbreviations used in the text are as follows: Eyes: ALE = anterior lateral eye; AME = anterior median eye; MOA = median ocular area; PLE = posterior lateral eye; PME = posterior median eye; RTA = retrolateral tibial apophysis.

Description
Small spiders, 4-6 mm in length.Carapace wedge-shaped or elongated, smooth or with plumose hairs; several long setae on clypeus and eye region; broadest of carapace at coxae Ⅱ-Ⅲ (Fig. 7a); anterior eye row slightly recurved in dorsal view and posterior eye row very wide and strongly recurved (Fig. 1a); fovea short, longitudinal, indistinct.Chelicerae same colour as carapace, both promargin and retromargin with two teeth.Sternum about as broad as long, slightly narrowed posteriorly.Leg formula 4123; femora Ⅰ-Ⅱ with one row of long bristles ventrally (usually four or eight), femora Ⅲ-Ⅳ with one or two long bristles ventrally (Fig. 3).Abdomen round or oval in females, elongate oval in males; with short or long grooved collar (Fig. 1b-d); anterior with one or two pairs of strongly erected spines (Fig. 2); dorsal scutum strongly sclerotized (Fig. 7a).

Diagnosis
The female of S. volans resembles that of S. muadai in having similar colouration and habitus, but can be distinguished by the following characteristics: 1) abdomen with a pair of sigilla (vs.absent in S. muadai) (cf.2012)).
Palp as in Fig. 8a-d.RTA subuliform, small.Sperm duct coiled and formed several loops; anterior with transverse U-shaped loop, middle double S-shaped, posterior with extra loop.Embolus straight spine-like process, with cataphracted stripes on surface.
Copulatory ducts long, stair-stepping and extended into black anterior spermathecae.

Diagnosis
The new species resembles that of S. suthepica in anterior abdomen with two pairs of strong spines, but can be distinguished by the following characteristics: 1) the longer embolus (vs.short in S. suthepica) (cf.

Etymology
The specific name an adjective and refers to the characters of the dorsal scutum with two rows of setae.Latin hispida = hispid.

Figure 9 .
Figure 9. Distribution map of the genus Serendib.